The fitness of infected organisms can vary greatly depending on the temperature at which they find themselves. Understanding the role of temperature in the fitness of infected organisms can be crucial to population studies, epidemiological studies, and when screening for biological control agents. We measured the effect of parasitism on host survival and reproduction at 4 constant temperatures using the acanthocephalan parasite Moniliformis moniliformis and its intermediate host, the cockroach Supella longipalpa. Infection did not affect cockroach survival at any temperature. Infection had a negative impact on cockroach fecundity but only at higher temperatures (28 and 31 C) and only later in infection (>20 days postinfection). At lower temperatures, infected and uninfected cockroaches had similar fecundities throughout the duration of the experiment (120 days). This study, along with previous studies, suggests that researchers would do well to consider environmental variables when exploring the effects of parasitism.

Counter to expectations of coevolved parasite–host relationships, parasites frequently infect hosts that never contribute to their reproduction, making the identification of a parasite's true host-specificity problematic. Pseudodelphis oligocotti (Nematoda: Dracunculoidea) infects several coastal Pacific fishes, but its course of development appears highly variable, suggesting that incidence does not reflect effective host range. To determine the host range of P. oligocotti and describe its relationship to various potential hosts, 24 fish species were examined from several British Columbia localities for prevalence, intensity, and extent and tissue location of parasite development. Pseudodelphis oligocotti infects 9 species of fishes from 5 orders, of which penpoint gunnel, Apodichthys flavidus, showed the highest prevalence and intensity, up to 80% and 19 (±17.1 SD) worms per host, respectively. Although subadult and adult P. oligocotti occurred in all 9 fishes, larvigerous P. oligocotti only occurred in A. flavidus and rarely in the northern clingfish, Gobiesox maeandricus. Infective first-stage larvae were recovered from gill tissue of A. flavidus. Thus, at most only 2 of the 9 host species infected by P. oligocotti actually contribute to its transmission. The occurrence of P. oligocotti in diverse hosts may be accounted for by the parasite's indiscriminant mode of transmission via ingestion of free-living intermediate copepod hosts, where highly exposed or more suitable fishes (or both) are closely related by diet and microhabitat. This study demonstrates how parasite transmission and host ecology can greatly affect observed host range and ultimately its potential for expansion.

An archived strain of Plasmodium vivax, isolated from Rio Meta, northern Colombia, in 1972 was adapted to grow in splenectomized Aotus lemurinus griseimembra and A. nancymai monkeys. Anopheles freeborni, An. maculatus, An. dirus, An. culicifacies, and An. albimanus were shown to be susceptible to infection by feeding on infected monkeys. Infections were more readily obtained by feeding on A. l. griseimembra than on A. nancymai. Transmission through sporozoites was obtained in an A. l. griseimembra monkey after a prepatent period of 24 days.

The comparison of parasite numbers or intensities between different samples of hosts is a common and important question in most parasitological studies. The main question is whether the values in one sample tend to be higher (or lower) than the values of the other sample. We argue that it is more appropriate to test a null hypothesis about the probability that an individual host from one sample has a higher value than individual hosts from a second sample rather than testing hypotheses about means or medians. We present a recently proposed statistical test especially designed to test hypotheses about that probability. This novel test is more appropriate than other statistical tests, such as Student's t-test, the Mann–Whitney U-test, or a bootstrap test based on Welch's t-statistic, regularly used by parasitologists.

A total of 76 adult individuals of Rana vaillanti were collected in Laguna Escondida, Los Tuxtlas, Veracruz, Mexico, and their helminth infracommunity structure was determined. Among the 21 helminth taxa collected (10 digeneans, 8 nematodes, and 3 acanthocephalans), the digenean Langeronia macrocirra reached the highest prevalence (64.4%), mean abundance (6.6), and mean intensity (10.4), as well as the highest total number of individuals (499). Only 2 frogs were uninfected, the remainder harbored between 1 and 7 helminth species and 1–102 individuals; mean species richness and abundance were 3.49 ± 0.22 and 16.1 ± 16.3, respectively. Langeronia macrocirra dominated in 50.6% of the infracommunities, with relatively low Berger– Parker index values (0.56); for this reason, the evenness was high (0.70 ± 0.31), and consequently, diversity values are the highest recorded to date in species of Rana. However, patterns of helminth infracommunity richness and diversity were similar to those previously observed in amphibians. This structure is attributed to the feeding habits (between 66.7 and 81% of helminth species parasitizing R. vaillanti enter using the food web dynamics) and low vagility (the remainder species infect by host penetration).

This epidemiologic study reports incidence, severity, and risk factors of swimmer's itch (cercarial dermatitis). Daily diaries about water exposures and swimmer's itch symptoms were completed by 40 riparian households at Douglas Lake, Michigan, for July 2000. Minutes spent in the water, minutes in shallow water, location, time of day, preventive action, age, and gender were recorded for all residents and guests. Incidence of swimmer's itch was 6.8 episodes per 100 water-exposure days. Probability of an episode increased with more days of water use and at locations with onshore winds. Episode severity increased with more time in the water and at the same locations. Age and gender had no effect on incidence or severity. In sum, onset and severity of swimmer's itch are affected by how people interact with the lake, not by their demographic features. More studies of human incidence and severity are needed to convince public health agencies to address this problem at recreational lakes. Study designs that combine epidemiologic and biological data will simultaneously inform public health education and biological control programs.

Colonization probabilities of parasite species often are determined by the habitat preference and vagility of host individuals. Although extinction-based interpretations have been investigated for nested subset patterns of parasite infracommunities, the low relative frequency of nestedness in colonization-dominated systems makes the determination and interpretation of nested infracommunities of broad ecological importance. In these systems, ontogenetic shifts in habitat preference or diet of the host have the potential to produce nested subset patterns of parasite infracommunities. Helminth infracommunity structure was investigated for 76 Rana vaillanti individuals collected from Laguna Escondida, Los Tuxtlas, Veracruz, Mexico, in 1998. Pooled helminth infracommunities were significantly nested, as were penetrating and ingested helminth infracommunities when considered separately. Richness, diversity, and evenness of the helminth infracommunities were not correlated with host size, and did not differ between host sexes, suggesting that the structure of infracommunities simply is a product of the interaction between host individuals and their landscape mediated by individual differences in vagility. It is hypothesized that individual differences in recruitment can produce nested subset infracommunity patterns when the habitats or habitat preferences of hosts are themselves nested.

Scabies is a contagious skin disease of humans and many other species of mammals. Previous studies suggested that the balance between the Th1 and Th2 immune responses may influence the outcome of a scabies infestation in a sensitized host. Therefore, in this study, we examined the T-helper cell cytokine profiles of splenocytes and lymph node cells in BALB/c mice that were immunized with scabies extract (primary response), infested with scabies mites (primary response), or immunized and then infested (secondary response). Lymphocyte cytokine expression was analyzed by flow cytometry after staining for intracellular cytokines. Immunization with scabies extract induced production of interferon-γ (IFNγ) (Th1 response) by both spleen and lymph node cells. Mice that were infested with scabies increased production of interleukin-4 by lymph node cells and of IFNγ by splenocytes. Mice that were first immunized and then infested with mites increased production of IFNγ by both spleen and lymph node cells. However, this increased level of IFNγ was only about half of that induced by immunization alone. These results suggest that live scabies mites produced something that inhibited IFNγ production in the lymph nodes of scabies-immunized mice. Our data also indicate that lymphocytes in the spleen and lymph nodes can present different cytokine response profiles.

In the present study, monoclonal antibodies (mAbs) against adult Ornithodoros moubata hemocytes were established. Afterward, artificial feeding was performed to assess the tickcidal effect of fetal bovine serum meal containing each mAb. As a result, Om21 showed the strongest tickcidal effect on adult female O. moubata. The reactivity of various tick cells and organs, including the hemocyte, midgut, trachea, ovary, fat body, and muscle, to Om21 was then examined by an indirect immunofluorescent antibody test and by immunoelectron microscopy. Om21 reacted with not only hemocytes but also with fat body cells, epidermis, cuticle of the trachea, connective tissue of the muscle, and the basement membrane of the midgut, trachea, fat body, oocyte, and epidermis. These results suggest that Om21 passing through the midgut epithelium induced a tickcidal effect on hemocytes or various organs. However, the target of Om21 could not be identified in the present study. The antihemocyte mAb produced in this study, Om21, may be useful for the immunological control of ticks.

Cats are important in the epidemiology of Toxoplasma gondii because they are the only hosts that can excrete environmentally resistant oocysts. The prevalence of T. gondii was determined in 58 domestic cats from 51 homes from Santa Isabel do Ivai, Paraná State, Brazil where a water-associated outbreak of acute toxoplasmosis had occurred in humans. Antibodies to T. gondii were found with the modified agglutination test in 49 of 58 (84.4%) cats at a serum dilution of 1:20. Tissues (brain, heart, and skeletal muscle) of 54 of these cats were bioassayed in T. gondii–free, laboratory-reared cats; T. gondii oocysts were excreted by 33 cats that were fed feline tissues. Brains from these 54 cats were bioassayed in mice; T. gondii was isolated from 7. Skeletal muscles and hearts of 15 cats were also bioassayed in mice; T. gondii was isolated from skeletal muscles of 9 and hearts of 13. The results indicate that T. gondii localizes in muscle tissue more than the brains of cats. In total there were 37 T. gondii isolates from 54 cats. Most isolates of T. gondii were virulent for mice. Genotyping of the 37 isolates of T. gondii, using the SAG2 locus, revealed that 15 isolates were type I and 22 were type III. The absence of type II genotype in cats in this study is consistent with the previous studies on T. gondii isolates from Brazil and is noteworthy because most T. gondii isolates from the United States are type II. These findings support the view that Brazilian and North American T. gondii isolates are genetically distinct. This is the first report of genotyping of T. gondii isolates from the domestic cat.

Schistosoma mansoni lung-stage larvae appear to not bind antibodies from radiation vaccine or infection sera in the membrane immunofluorescence test. However, treatment of ex vivo lung-stage schistosomula with methyl-β-cyclodextrin, a hydrophobic oligosaccharide that specifically extracts cholesterol from plasma membranes, induced readily detectable binding of specific antibodies in a concentration- and time-dependent manner. Surface membrane antigen binding of specific antibodies was also conclusively demonstrated by quantitative absorption of anti-schistosome sera with intact ex vivo larvae. These data together suggest that confinement of lung-stage schistosomula surface membrane antigens in cholesterol-rich sites allows only monovalent antibody binding, which can be detected by absorption and not by direct serology.

C57Bl/6 mice develop significant levels of protection to a challenge infection after percutaneous exposure to irradiated Schistosoma mansoni cercariae. Although some circumstantial evidence has suggested that antigen-presenting cells (APCs) within the skin play a role in priming anti-schistosomula effector mechanisms, no direct evidence has been presented. In this study, we describe efforts to directly test whether skin-resident APCs exposed to irradiated cercariae are capable of mediating responses consistent with previously proposed mechanisms associated with delayed-type hypersensitivity reactions. We demonstrate that a population of APCs emigrates from the skin after percutaneous vaccination and that these cells are able to induce proliferation of S. mansoni–specific lymphocytes. We describe our experiments conducted to confirm that proliferation is dependent on major histocompatibility complex (MHC) Class-II interactions and cell-to-cell contact between APCs and lymphocytes. Immunohistological staining of emigrating cells revealed a population of large MHC Class-II cells with a morphology characteristic of mature dendritic cells. On recovery and adoptive transfer into naive mice, these cells demonstrated the ability to mediate protection to a challenge infection at levels similar to those in percutaneously vaccinated controls. This confirms that cutaneous APCs can initiate anti–schistosomula effector mechanisms in C57Bl/6 mice after percutaneous vaccination.

Trypanosome-derived lymphocyte-triggering factor (TLTF) produced by Trypanosoma brucei brucei stimulates production of interferon-γ (IFN-γ) by CD8 T cells, and it is reported that, in turn, IFN-γ stimulates proliferation of T. b. brucei. We studied the role of TLTF in trypanosome proliferation using the Wellcome strain (WS) of Trypanosoma brucei gambiense and the ILtat 1.4 strain (IL) of T. b. brucei. Increase in the number of WS in infected rats is more rapid than IL and corresponds with comparatively higher levels of IFN-γ. Production of IFN-γ, as measured by protein and messenger RNA (mRNA) levels, was maintained by splenocytes from WS-infected rats, whereas levels decreased in IL-infected rats, accompanied by prolongation of infection. Expression of TLTF mRNA by in vitro–cultured WS was promoted in a dose-dependent fashion by addition of recombinant rat IFN-γ at all concentrations tested. The addition of lower concentrations of IFN-γ to cultured IL increased expression of TLTF mRNA, whereas, in contrast to WS, addition of 100 and 1,000 U/ml IFN-γ decreased expression of TLTF by IL. These results show that unlike WS, elevated IFN-γ concentrations lead to decreased TLTF production by IL. It is believed that decreased TLTF production in IL-infected rats leads to lowered IFN-γ production, thereby slowing IL proliferation.

This work reports the detection of specific immunoglobulins (Ig) against rFh8, a recombinant Fasciola hepatica adult worm excretion–secretion antigen, in sera from experimentally (rabbit, Wistar rat, cattle, and sheep), or naturally (human) infected hosts. In the case of laboratory experimental models the study revealed significant differences between rabbits, which recognized the recombinant antigen all along the infection, and Wistar rats, which showed high anti-rFh8 Ig levels only for a short period of the infection. Available sera from experimentally infected cattle and sheep, as well as sera from naturally F. hepatica–infected humans, also contained significant levels of Ig against rFh8, suggesting that Fh8 was produced by F. hepatica at a very early stage of infection in all hosts so far analyzed and that the rFh8 antigen could be used as a tool for the diagnosis of F. hepatica infections.

This study reports on the kinetics of antibody production to Echinostoma caproni and the dynamics of antigens in feces and sera in 2 experimental hosts (hamsters and rats) that display different degrees of susceptibility with this echinostome. Echinostoma caproni produced chronic infections in hamsters, whereas rats lost the infection at 49–56 days postinfection (DPI). Hamsters developed higher antibody responses than rats, probably in relation to different intestinal absorptions of worm antigens in each host species. The levels of coproantigens were indicative of the course of infection in each host. Positive coproantigen levels were detected at 1–2 DPI in both hosts, and the values remained positive until the end of the experiment in hamsters; in rats, the coproantigen levels reverted to negative values, coinciding with the loss of infection. High levels of circulating antigens were detected in hamsters from 21 DPI to the end of the study. In contrast, low levels of E. caproni seroantigens were detected in rats only. These observations may reflect the differences in local inflammatory responses induced by E. caproni in each host species.

The icthyosporean, Capsaspora owczarzaki, a known predator of Schistosoma mansoni sporocysts in vitro, is more prevalent in laboratory-reared strains of the intermediate snail host, Biomphalaria glabrata resistant to S. mansoni, than from the susceptible M line strain. We examined whether B. glabrata resistant to the NIH-PR-1 strain of S. mansoni from 2 regions in Brazil were also host to C. owczarzaki. Symbiont presence was examined using hemolymph culturing and nested polymerase chain reaction of snail genomic DNA with primers designed to specifically amplify sequences from relatives of the Icthyosporea. All B. glabrata of the resistant Salvador strain from the laboratory of Dr. Lobato Paraense in Rio de Janeiro, Brazil (n = 46) tested negative for symbionts. Three of 18 semiresistant 10-R2 B. glabrata from the laboratory of Dr. Barbosa in Recife, Brazil tested positive for C. owczarzaki. Another icthyosporean, Anurofeca sp., was identified from 1, 10-R2 snail and from 2 of 12 field-collected B. glabrata from Praia do Forte Orange, Ilha de Itamaracá. Snails from 2 other sites, Hotel Colibri, Pontezinha and Praia do Sossego, Ilha de Itamaracá, were negative for Anurofeca. Two genera of ciliates were also identified. Paruroleptus sp. was found in 4, 10-R2 snails and Trichodina sp. was identified in 2 field-collected snails from Praia do Forte Orange and Praia do Sossego.

We studied the effects of high temperature, 30 and 32 versus 27 C on early Plasmodium falciparum development in Anopheles gambiae experimentally infected with gametocytes from 30 volunteers with mean density of 264.1 gametocytes/μl blood (range: 16–1,536/μl). From several batches of mosquitoes, fed by membrane feeding, midguts of individual mosquitoes were dissected at 24 hr for ookinete enumeration and at 7 days to quantify oocysts. There were temperature-related differences in mean ookinete intensity per mosquito midgut, with 9.71 ± 1.6 at 27 C, 9.85 ± 2.32 at 30 C, and 3.89 ± 0.81 at 32 C. The prevalence of oocyst infection decreased with an increase in temperatures from 15.9 to 8.5 to 6.4% at 27, 30, and 32 C, respectively. The average oocyst intensities for the infected mosquitoes increased with temperatures from 2.9 at 27 C to 3.5 at 30 C, and to 3.3 at 32 C. However, the success of infections was reduced at 30 and 32 C, and resulted in greater losses during consecutive inter-stage parasite development. The most significant impact of high temperatures occurred at the transition between macrogametocytes and ookinetes, whereas the transition between ookinetes and oocysts apparently was not affected. In contrast to other reports, exposure of mosquitoes infected with natural parasites to high temperatures did not eliminate preoocyst stages, as has been observed from laboratory studies using the NF-54 strain of P. falciparum. This observation of parasite resistance to high temperatures is consistent with the natural situation in tropical environments where perennial malaria transmission occurs during hot dry seasons.

Molecular and biological characteristics of a new species of Cryptosporidium from the feces of pigs (Sus scrofa) is described. Oocysts are structurally indistinguishable from those of Cryptosporidium parvum; they are passed fully sporulated, lack sporocysts, and measure 4.9–4.4 μm (mean = 4.6 μm) × 4.0–4.3 μm (mean = 4.2 μm); length to width ratio 1.1 (n = 50). Cryptosporidium suis is not transmissible to nude mice and is poorly infectious for cattle. Molecular and phylogenetic analyses at the 18S ribosomal RNA, heat shock protein 70, and actin gene loci demonstrate C. suis to be genetically distinct from all known species and genotypes of Cryptosporidium, and thus is named as Cryptosporidium suis.

Raccoon roundworms (Baylisascaris procyonis) and other Baylisascaris species cause patent or latent larva migrans (LM) in a variety of mammals and birds, including humans. It is not clear whether LM by Baylisascaris transfuga, roundworms of bears, is associated with clinical neurological disorders. To clarify this issue, ICR and BALB/c mice as well as Mongolian jirds (Meriones unguiculatus) were orally inoculated with 2,000–5,000 embryonated eggs of B. transfuga. In mice, the ascarid caused symptomatic LM of limited extent and duration, whereas the infection was fatal in jirds; i.e., they exhibited general signs such as severe depression and emaciation on days 8–11 postinfection (PI) and died, or they developed progressive and fatal neurological disorders after day 14 PI. Histological examination showed B. transfuga larvae in the brain of all mice and jirds examined, and the larvae collected from them developed to a size comparable with that of B. procyonis. There existed, however, critical differences in host reactions against larvae localized in the brain of mice and jirds; B. transfuga larvae found in mice were surrounded by granulomatous reactions and immobilized, whereas larvae found in jirds were free from any host reaction and mobile, causing extensive malacia.

Sarcocystis neurona is an apicomplexan parasite that is the primary etiologic agent of equine protozoal myeloencephalitis in horses. Protective immune responses in horses have not been determined, but interferon-γ (IFN-γ) is considered critical for protection from neurologic disease in mice. The role of adaptive and innate immune responses in control of parasites was explored by infecting BALB/c, IFN-γ knockout (GKO), and severe combined immune deficient (SCID) mice with S. neurona (10⁴ sporocysts/mouse). Immune competent BALB/c mice eliminated parasites within 30 days, with no sign of neurologic disease, whereas GKO mice developed fulminant neurologic disease. In contrast, SCID mice remained healthy throughout the experimental period despite the persistence of parasite at low levels in some mice. Treatment with anti–IFN-γ antibody resulted in neurologic disease in infected SCID mice. Although SCID mice lack adaptive immune responses, they have natural killer (NK) cells capable of producing significant quantities of IFN-γ. Therefore, SCID mice were infected with sporocysts of S. neurona and treated with anti-asialo GM1. Depletion of NK cells, confirmed by flow cytometry, did not result in neurologic disease in SCID mice. These results indicate that IFN-γ mediates protection from neurologic disease in SCID mice. Protective levels of IFN-γ may originate from a low number of nondepleted NK cells or from a non-T cell, non-NK cell population.

Oceanobdella khani n. sp. is described from the plain sculpin, Myoxocephalus jaok, from Bristol Bay, Alaska, in the eastern Bering Sea. Prevalence was never greater than 10% in any single collection; maximum intensity was 12 leeches per host, but most fish had 5 or fewer leeches. Oceanobdella khani possesses generic characters of small oral sucker, 5 pairs of testisacs, unremarkable terminal male reproductive organs, coelomic system lacking pulsatile vesicles, and 3 pairs of eyes on the oral sucker–trachelosome. Oceanobdella khani is distinguished from other species in the genus by solid black pigmentation on the urosome, clitellum, trachelosome, and most of the oral sucker except for an unpigmented margin. The pigmentation of the caudal sucker is highly variable, ranging from overall mottled blackish gray to completely unpigmented. The caudal sucker lacks ocelli. Intestinal ceca are large, crop ceca are directed anteriorly, and postceca are separate for their entire length.

A new hepatic dicrocoeliid species, Brachylecithum mackoi n. sp. (Digenea, Dicrocoeliidae), is described from the European hedgehog, Erinaceus europaeus (L.) (Insectivora, Erinaceidae). An infected host was found in the Mediterranean island of Elba (Italy), and more than 60 individuals were isolated from the biliary ducts. The holotype and 55 paratypes were examined. Brachylecithum mackoi n. sp. differs from congeneric species found in mammal hosts by having well-developed lappets in the ventral sucker, a sloping uterus between anterior testis and acetabulum, no overlap between vitellaria, and metrical features in the body size, sucker diameters, cirrus sac, and size of eggs. The only other Brachylecithum species of erinaceids in Europe and Africa, Brachylecithum aetechini Dollfus, 1951, differs from the new species in the above-mentioned morphological characters, greater dimensions of the body, and oral sucker, pharynx, cirrus sac, and egg dimensions. The presence of B. mackoi n. sp. in Elba Island is discussed in the light of apparent host specificity of erinaceid dicrocoeliids and geographical distribution of Palearctic and Ethiopian Erinaceidae.

Many bird species host several lineages of apicomplexan blood parasites (Protista spp., Haemosporida spp.), some of which are shared across different host species. To understand such complex systems, it is essential to consider the fact that different lineages, species, and families of parasites can occur in the same population, as well as in the same individual bird, and that these parasites may compete or interact with each other. In this study, we present a new polymerase chain reaction (PCR) protocol that, for the first time, enables simultaneous typing of species from the 3 most common avian blood parasite genera (Haemoproteus, Plasmodium, and Leucocytozoon). By combining the high detection rate of a nested PCR with another PCR step to separate species of Plasmodium and Haemoproteus from Leucocytozoon, this procedure provides an easy, rapid, and accurate method to separate and investigate these parasites within a blood sample. We have applied this method to bird species with known infections of Leucocytozoon spp., Plasmodium spp., and Haemoproteus spp. To obtain a higher number of parasite lineages and to test the repeatability of the method, we also applied it to blood samples from bluethroats (Luscinia svecica), for which we had no prior knowledge regarding the blood parasite infections. Although only a small number of different bird species were investigated (6 passerine species), we found 22 different parasite species lineages (4 Haemoproteus, 8 Plasmodium, and 10 Leucocytozoon).

Pelecitus meridionaleporinus n. sp. from the Tehuantepec jackrabbit is described. The new species differs from Pelecitus helicinus (Molin, 1860) in having delicate transverse striations, a salient vulva, and a readily apparent preesophageal ring; P. helicinus has teardrop cells around the vulva, which are lacking in the species presently described. The new species is different from Pelecitus scapiceps (Leidy, 1886) in having the vulva anterior to the esophageal–intestinal junction and wider lateral alae. Pelecitus scapiceps is found in the tarsal bursa of the hind feet of lagomorphs, whereas P. helicinus is found around tendons of legs and feet of birds. Pelecitus meridionaleporinus n. sp. occurs in the subcutaneous tissue at the base of both ears. This is the second species in Pelecitus Railliet and Henry, 1910 that occurs in New World lagomorphs, and the third found infecting mammals.

A total of 8 specimens of Urophycis brasiliensis (Kaup, 1858) from waters off Mar del Plata, Argentina (38°08′S, 57°32′W), were examined for parasitic nematodes. A new nematode species, Cucullanus bonaerensis n. sp., is described (prevalence 50%, mean intensity 15.5). The new species differs from its congeners in the distribution pattern of caudal papillae (particularly fourth pair) and phasmids, length of the body and spicules, and by the position of the excretory pore (in the posterior third of esophagus). Species of Cucullanus, reported previously as C. heterochrous Rudolphi, 1812, and Cucullanus sp. from U. brasiliensis from Puerto Quequén, Argentina (38°37′S, 58°53′W), are considered as members of the new species.

A new species of philometrid nematode (Nematoda: Philometridae), Philometroides buirnurensis sp. n., is described and illustrated on the basis of female specimens from subcutaneous tissues of the inner surface of the abdominal cavity and the bile duct of cyprinid fishes Leucisuus waleckii (Dybowski), 1869 (type host), Pseudaspius leptocephalus (Pallas), 1776 and Hemiibarbus labeo (Pallas), 1776, from the Buir Nur Lake, a boundary lake between China and Mongolia, on southwest of the Hulun Buir League in the Inner Mongolia Autonomous Region of China. The new species distinctly differs from its congeners mainly in that the posterior half of its body is tapered and conspicuously narrower than the anterior region and that both the head and tail ends are rounded. The cuticular bosses are distributed extensively at both ends but poorly on the middle part of the body. The most peculiar feature of the bosses situated at both ends was their lobe- or rodlike shape and their transverse orientation. Four pairs of submedian outer cephalic papillae and 1 pair of caudal papilla are all relatively large. The new species differs from the most similar congener, Philometroides ganzhouensis Yu, 1998, in having 4 inner cephalic papillae and in the presence of 2 caudal papillae in mature specimens.

The second internal transcribed spacer (ITS2) of the ribosomal RNA genes of Diplozoon paradoxum and Paradiplozoon nagibinae were amplified and sequenced. The polymerase chain reaction product of D. paradoxum was bigger (840 bp) than that of P. nagibinae (820 bp). There was no intraspecific variability recorded in sequences from either species. Sequence comparisons and ITS2 restriction fragment length polymorphism (RFLP) pattern of 8 European diplozoid species aimed to resolve their identification and amend the previous studies. RFLP was used to distinguish the 2 species from each other and from P. bliccae, P. homoion, P. megan, P. pavlovskii, P. sapae, and Eudiplozoon nipponicum, using restriction enzymes AluI, HaeIII, HinfI, RsaI, and SphI. The criteria for morphological identification of 8 European diplozoids are also included, with the main morphological characters of clamps, trapeze spur, and anterior joining sclerites of 8 diplozoid species being illustrated. Combination of the shape and comparison of length of the trapeze spur and anterior joining sclerites could lead to accurate identification of diplozoid species.

Similascarophis (Cystidicolidae) n. gen. is proposed. In the mouth of specimens of this genus, submedial labia are absent and pseudolabia do not have any part projecting toward the central oral opening. These nematodes were obtained from the alimentary tract of 7 marine fish species along the coast of Chile: Bovichthys chilensis Regan, Eleginops maclovinus (Cuvier), Pinguipes chilensis (Valenciennes), Cilus gilberti (Abbott), Cheilodactylus variegatus Valenciennes, Girella laevifrons (Tschudi), and Graus nigra Philippi. Morphology and morphometry are compared between 2 new Similascarophis species: Similascarophis maulensis n. sp. and S. chilensis n. sp., which differ in the presence of sublabia and in the length of the glandular esophagus and left spicule. We also recorded Similascarophis sp. in 2 other host species, which showed some distinct proportional measurements, although these differences were not sufficiently clear to identify them as a new species.

Two enzyme-linked immunosorbent assay (ELISA) systems, one using natural excretory–secretory (ES) antigens and the other a synthetic glycan antigen (3,6-dideoxy-d-arabinohexose [tyvelose, TY]), were evaluated for the serological diagnosis of trichinellosis in swine. Sensitivity was estimated using samples (n = 113) collected 3–21 wk PI from 15 experimentally infected pigs, and specificity was estimated using samples (n = 397) from a population of Trichinella spp.–free pigs. Results were analyzed using 2 cutoff values recommended in international guidelines (Office Internationale des Epizooties [OIE]) and by the optimal cutoff level as determined by receiver–operator characteristic (ROC) analysis. The ROC-optimized TY-ELISA consistently performed better than all other combinations. None of the combinations of test and cut-off detected infected pigs sooner than 35 days; however, the ROC-optimized TY-ELISA identified 8 of 15 pigs earlier than the ES-ELISA and detected 2 pigs missed by all other tests. At 49 days PI the sensitivity and specificity of the ROC-optimized TY-ELISA were 94.3 and 96.7%, respectively, as compared with the ROC-optimized ES-ELISA at 84.9 and 96.0%, respectively. The ROC-optimized TY-ELISA was 100% specific at OIE-recommended cut-offs. This study indicates that the TY-ELISA is as good or better than the ES-ELISA for the detection of trichinellosis in swine.

Methods for killing Echinococcus multilocularis eggs within stool or intestinal samples, without damaging the diagnostic value of the sample, would significantly reduce the risk of animal health providers acquiring alveolar hydatid disease. The first objective of this study was to determine whether E. multilocularis eggs located in fox intestines can survive storage at −70 C for at least 4 days. Results showed that none of 72,000 E. multilocularis eggs remained infectious to defined strains of mice under these conditions, yet, similar eggs recovered from nonfrozen carcasses stored at 4 C for the same time period were viable. The structural identities of adult worms and eggs were not significantly altered by the freezing and thawing processes. These results indicate that ultracold temperatures can be used to kill or inactivate E. multilocularis eggs, making them safe to handle when diagnosing this parasite in definitive hosts. The second objective of this study was to determine whether E. multilocularis eggs could survive freezing to −70 C if commonly used cryopreservation protocols were used. The use of the cryoprotectant solution, 5% dimethyl sulfoxide–35% saline–60% lamb serum, with a −1 C/min freezing rate was unable to prevent the eggs from being killed by freezing to −70 C. Rapid cooling by plunge freezing into liquid nitrogen was also lethal to E. multilocularis eggs. Only a few of the many potential cryopreservation protocols were tested in this study, so it is not yet possible to completely rule out the possibility of preserving these eggs at ultralow temperatures, but it does indicate that temperatures below −70 C are lethal to eggs even under favorable storage conditions.

A capture enzyme-linked immunosorbent assay (ELISA) using a new monoclonal antibody (mAb MM3) is reported for the detection of Fasciola hepatica excretory–secretory antigens (ESAs) in feces of infected hosts. The mAb MM3 was produced by immunization of mice with a 7- to 40-kDa purified and O-deglycosylated fraction of F. hepatica ESAs, which has previously been shown to be specific for the parasite. The specificity and sensitivity of the MM3 capture ELISA were assessed using feces from sheep and cattle. Sheep feces were obtained from a fluke-free herd (with most animals harboring other nematodes and cestodes), from lambs experimentally infected with 5–40 F. hepatica metacercariae and in some cases treated with triclabendazole at 14 wk postinfection (PI), and from uninfected control lambs. Cattle feces were collected at the slaughterhouse from adult cows naturally infected with known numbers of flukes (from 1 to 154) or free of F. hepatica infection (though in most cases harboring other helminths). The MM3 capture ELISA assay had detection limits of 0.3 (sheep) and 0.6 (cattle) ng of F. hepatica ESA per milliliter of fecal supernatant. The assay detected 100% of sheep with 1 fluke, 100% of cattle with 2 flukes, and 2 of 7 cattle with 1 fluke. The false-negative animals (5/7) were probably not detected because the F. hepatica individuals in these animals were immature (5–11 mm in length). As expected, coproantigen concentration correlated positively (r = 0.889; P < 0.001) with parasite burden and negatively (r = 0.712; P < 0.01) with the time after infection at which coproantigen was first detected. Nevertheless, even in animals with low fluke burdens (1–36 parasites), the first detection of F. hepatica–specific coproantigens by the MM3 capture ELISA preceded the first detection in egg count by 1–5 wk. In all sheep that were experimentally infected and then untreated, coproantigen remained detectable until at least 18 wk PI, whereas in sheep that were experimentally infected and then flukicide treated, coproantigen became undetectable from 1 to 3 wk after treatment. None of the fecal samples from sheep or cattle negative for fascioliasis but naturally infected with other parasites including Dicroelium dendriticum showed reactivity in the MM3 capture ELISA. These results indicate that this assay is a reliable and ultrasensitive method for detecting subnanogram amounts of F. hepatica antigens in feces from sheep and cattle, facilitating early diagnosis.

A total of 1,030 patients, 40.2% men and 59.8% women, identified during the period of October 1998 to November 2002 as having cutaneous leishmaniasis (CL), were studied; 1,431 lesions were identified in the 1,030 patients. One lesion was present in 80.7% of the patients. The size of the lesions (longest axis) was 13.6 mm (standard, 12.1 mm; range 3–150 mm). Most of the lesions were of the papular type (51.2%), although several atypical clinical presentations of CL were observed. The duration of the disease ranged between 1 and 72 mo (mean duration, 10.8 mo). The clinical suspicion of CL was confirmed by the observation of amastigotes on lesion tissue samples stained by Giemsa. The test was positive in 851 of 1,030 patients (82.6%). Intralesional meglumine antimonate solution (85 mg Sb/ml, 0.2–1 ml, depending on the size of the lesion) weekly until complete cure or up to 20 wk was used for first-line therapy of 890 patients (86.4%). We found that this regimen of intralesional Sb has an efficacy of 97.2% with a low relapse rate of 3.9% and no serious adverse side effects.

Thirty-one South American sea lion pups (Otaria flavescens) found dead in Punta León, Argentina, during the summer of 2002, were examined for hookworms (Uncinaria hamiltoni). Parasite parameters were analyzed in 2 locations of the rookery, i.e., a traditional, well-structured breeding area and an expanding area with juveniles and a lax social structure. Prevalence of hookworms was 50% in both localities, and no difference was observed in prevalence between pup sexes (P > 0.05). Hookworms were concentrated in the small intestine. Transmammary transmission is assumed because only adult hookworms were found in the pups. The mean intensity of hookworms per pup was 135; the mean intensity in females (92.78) was significantly different (P < 0.05) from that of males (230.25). No difference (P > 0.05) in intensity was found between the 2 breeding areas, although prevalence was higher in the traditional breeding area than in the other area. Location was the only factor affecting hookworm prevalence (P log-linear model: 0.9552; χ²: 1.5629). No apparent trend between body condition and intensity of hookworms was observed.

Neospora caninum was isolated from the brain of a 6-mo-old aborted bovine fetus from Galicia, Spain. The fetal brain homogenate was inoculated intraperitoneally into cortisonized mice. The peritoneal exudate from the infected mice, along with mouse sarcoma cells (Tg180), was inoculated into a second group of mice, and parasites were harvested from the peritoneal exudate. The parasites were adapted to in vitro growth in Vero monolayers. The tachyzoites from the peritoneal exudate reacted positively with anti–N. caninum antibodies and not with anti–Toxoplasma gondii antibodies on indirect fluorescent antibody test. The tachyzoites were lethal to interferon gamma gene knock out (KO) mice and could be identified immunohistochemically in the tissues. The identity of the parasite was also confirmed by polymerase chain reaction amplification of N. caninum–specific fragments. The sequences of the amplified gene 5 fragments (GenBank AY494944) were found to be identical to that of an Austrian isolate of N. caninum but not to that of NC-1. This is the first isolation of viable N. caninum from Spain.

Neospora caninum is a cyst-forming coccidian that mainly affects bovines, although Neospora infection has also been described in other domestic and wild ruminant species. Serum samples from 78 alpacas (Vicugna pacos) and 73 llamas (Lama glama) at a unique dilution of 1:50 tested by indirect fluorescent antibody test (IFAT) were further analyzed serologically by IFAT and Western blot in both ruminant species to avoid cross-reactions with closely related coccidian parasites and to confirm the existence of N. caninum–specific antibodies. IFAT titers ranging between 1:50 and 1:800 were found. When using Western blot, N. caninum tachyzoite–specific immunodominant antigens with apparent molecular weights of 17–18, 34–35, 37, and 60–62 kDa were also recognized, although some sera with 1:50 IFAT titers proved not to have N. caninum–specific antibodies. As expected, higher IFAT titers were associated with higher anti–N. caninum reactivity in Western blot. This report documents for the first time the presence of N. caninum infection in adult alpacas and llamas from Peru.

Saimiri boliviensis monkeys were infected by the intravenous injection of 50 sporozoites of the H strain of Plasmodium knowlesi dissected from the salivary glands of Anopheles dirus mosquitoes; prepatent periods were 11, 12, 13, 13, 13, and 16 days. Sporozoites of P. knowlesi stored frozen for 7 days, 53 days, 20 mo, 7 yr and 7 mo, and 11 yr and 5 mo induced infections in Macaca mulatta monkeys with prepatent periods of 7, 6, 8, 10, and 7 days, respectively. After frozen storage for 11 yr and 5 mo, infections were induced in S. boliviensis with prepatent periods of 10–13 days.

The molecular mechanism of benzimidazole (BZ) resistance in cyathostomins of horses is still unclear. Previous studies revealed that the TTC or TAC polymorphism in codon 200 of the beta-tubulin isotype 1 gene is not as strictly correlated with BZ resistance as in trichostrongyles in sheep. To identify further sites of polymorphism within the beta-tubulin gene related to BZ resistance, complete complementary DNAs (cDNAs) encoding beta-tubulin of adult worms of Cylicocyclus nassatus, Cyathostomum pateratum, Cyathostomum coronatum, Cyathostomum catinatum, Cylicostephanus longibursatus, and Cylicostephanus goldi of a BZ-resistant cyathostomin population were characterized using specific primers. The cDNA sequence of each species spans 1,429 bp, encoding a protein of 448 amino acids. The interspecific identities are 95.2–99.6% at the nucleotide and 98.7–100.0% at the peptide level. The comparison of the amino acid sequences of individuals isolated from the BZ-resistant cyathostomin population with those from individuals of Cc. nassatus, Cy. coronatum, Cy. pateratum, and Cy. catinatum of a BZ-susceptible one showed differing amino acids in 11 positions. The commonness of a phenylalanine to tyrosine mutation at position 167 in all the 6 cyathostomin species isolated from a BZ-resistant population suggests its involvement in the molecular mechanism in BZ resistance.

From a natural population that inhabits the dry evergreen forest at Polonnaruwa, serum samples of 170 toque macaques were examined for antibodies to Toxoplasma gondii by the modified agglutination test. Of these, 21 (12%) were found with titers of 1:16 in 9, 1: 32 in 9, 1:256 in 1, 1:1,024 in 1, and 1:4,096 in 1. There was no evidence of maternal transmission of antibodies or congenital toxoplasmosis. None of the infected macaques died within 1 yr after sampling. Toxoplasma gondii infection was closely linked to human environments where domestic cats were common. Macaques having frequent contact with human settlements showed a significantly greater (P < 0.0001) prevalence (19% infected) than macaques restricted to forest habitat, none of which was infected. Although infection with T. gondii has been noted in several species of Asian primates, this is the first report of T. gondii antibodies in toque macaques (Macaca sinica) that are endemic to the island of Sri Lanka.

Sarcocystis neurona has become recognized as the major causative agent of equine protozoal myeloencephalitis (EPM) in the Americas. At least 3 pathogenic species of Sarcocystis, including S. neurona, can be isolated from opossums. Methods are needed to ascertain whether these isolates are viable and capable of causing infections. In this study, the nuclear stain propidium iodide (PI) was used to differentiate between live (viable) and heat-killed (nonviable) S. neurona sporocysts. PI was excluded by live sporocysts but penetrated compromised sporocyst membrane and stained sporozoite nuclei of dead sporocysts. After live and dead sporocysts were mixed at various ratios, the number of unstained sporocysts detected after the staining procedure correlated significantly (r² = 0.9978) with the expected numbers of live sporocysts. Sporocyst mixtures were also assayed for in vitro excystation and development in tissue cultures. The correlation between the percentage of plaques formed in tissue cultures and the percentage of expected infectious (live) sporocysts in each mixture was r² = 0.6712. By analysis of variance, no statistically significant difference was measured between the percentage of viable sporocysts and the percentage of infectious sporocysts (P = 0.3902) in each mixture. In addition, there was evidence of a relation between PI impermeability of sporocysts and animal infectivity. These results suggest that the PI dye–exclusion technique can be a useful tool in identifying viability and potential infectivity of S. neurona sporocysts and in differentiating between viable and nonviable sporocysts.

A member of the Fasciola hepatica saposinlike/NK-lysin protein family with lytic activity on human peripheral blood mononuclear cells and erythrocytes was recently described. The current study was designed to test the immunoprophylactic potential of this protein termed FhSAP-2 against infection with F. hepatica in rabbits. Two doses of 50 μg of recombinant FhSAP-2 (rFhSAP-2) emulsified in TiterMax were injected subcutaneously on the dorsal surface of 4 rabbits at 2-wk intervals. Four weeks after the second immunization, the rabbits were infected orally with 25 F. hepatica metacercariae. Four non-immunized–infected rabbits were used as controls. An enzyme-linked immunosorbent assay revealed high levels of antibodies to both rFhSAP-2 and F. hepatica excretory–secretory antigens by 2 wk after the first immunization, which were always significantly higher in immunized–infected rabbits than in control-infected rabbits. On the completion of the trial, vaccinated rabbits had 81.2% less flukes than controls. Moreover, F. hepatica egg counts in feces, as well as in bile collected from the gall bladders from vaccinated animals, were lower, 83.8 and 73%, respectively, compared with controls. The vaccinated rabbits also had significantly lower amounts of parasite antigen in stool and bile samples than controls. Last, evaluation of macroscopic liver lesions revealed that the rabbits vaccinated with rFhSAP-2 had milder lesions than the infected-control rabbits. These findings support the hypothesis that this novel rFhSAP-2 protein has immunoprophylactic potential against fascioliasis in rabbits including antifecundity and antipathology effects. This is the first report on experimental vaccination of rabbits against F. hepatica with a purified, defined, recombinant protein related to a member of the saposinlike protein family.

Measures of parasitemia by intraerythrocytic hematozoan parasites are normally expressed as the number of infected erythrocytes per n erythrocytes and are notoriously tedious and time consuming to measure. We describe a protocol for generating rapid counts of nucleated erythrocytes from digital micrographs of thin blood smears that can be used to estimate intensity of hematozoan infections in nonmammalian vertebrate hosts. This method takes advantage of the bold contrast and relatively uniform size and morphology of erythrocyte nuclei on Giemsa-stained blood smears and uses ImageJ, a java-based image analysis program developed at the U.S. National Institutes of Health and available on the internet, to recognize and count these nuclei. This technique makes feasible rapid and accurate counts of total erythrocytes in large numbers of microscope fields, which can be used in the calculation of peripheral parasitemias in low-intensity infections.

Equine protozoal myeloencephalitis is the most important protozoan disease of horses in North America and is usually caused by Sarcocystis neurona. Natural and experimentally induced cases of encephalitis caused by S. neurona have been reported in raccoons (Procyon lotor) and raccoons are an intermediate host for this parasite. A 3-yr-long serological survey was conducted to determine the prevalence of agglutinating antibodies to S. neurona in raccoons collected from Fairfax County, Virginia, a suburban–urban area outside Washington, D.C. Samples from 469 raccoons were examined, and agglutinating antibodies (≥1:50 dilution) were found in 433 (92.3%) of the raccoons. This study indicates that exposure to S. neurona is high in this metropolitan area.

The myxosporean parasite Parvicapsula minibicornis is described from adult sockeye and coho salmon during spawning migrations in tributaries of the Columbia River in Canada and the United States. These observations extend the known distribution of this parasite from the Fraser River drainage basin. The parasite was identified in Columbia River salmonids using polymerase chain reaction (PCR) and by in situ hybridization, but unlike in Fraser River salmon, it was not observed in conventional histological preparations of the kidney. Prevalence of the parasite determined by PCR was higher in spawning sockeye from the Fraser River than in those from the Okanagan River. Our ability to explain the relatively low prevalence and absence of clinical P. minibicornis infections in Columbia River salmon is hampered by our poor understanding of the life cycle of this parasite.

This study was undertaken to observe the effects of hydrogen peroxide on Cryptosporidium parvum oocysts with respect to protease activity in comparison to known protease inhibitors. In assessing the possible mechanisms of action of hydrogen peroxide, treatment effectiveness was analyzed using 3 assays and the potential roles of proteases and cations were considered. Treatment of C. parvum oocysts with hydrogen peroxide inhibited protease activity up to 50% compared with untreated controls. Treatment of oocysts with chemicals that affect sulfhydryls, including N-ethylmaleimide and dithiolthreitol, inhibited protease activity by >90%. Treatment of oocysts with these chemicals, along with the protease inhibitors, phenylmethylsulfonyl fluoride (PMSF), ethylenediamine-tetraacetic acid, and cystatin, inhibited protease activity as well as in vitro excystation and infection in a cell culture assay. Several mechanisms may result in the successful inhibition of infection and excystation by hydrogen peroxide treatment, including: oxidation of oocyst wall proteins or lipids, chelating of cations necessary for infection, or hydroxyl radical–induced DNA damage to sporozoites, or both.

A total of 6 helminth species were recorded during helminthological examination of 50 Chapalichthys encaustus from Lake Chapala, Jalisco, Mexico. Helminth species identified included: Salsuginus sp. (an undescribed monogenea); Posthodiplostomum minimum (metacercariae); Cyclustera ralli (metacestode); Polymorphus brevis (cystacanth); Contracaecum sp. (nematode larvae); and Rhabdochona lichtenfelsi (adult nematode). Of these, 2 (Salsuginus sp. and R. lichtenfelsi) are specialist species. The observed species richness, individual parasite abundance, and diversity were low. Data suggest that host specificity is an important factor contributing to observed community composition and richness. Host feeding habits and helminth species availability seem to determine the characteristics of these helminth assemblages.

Calreticulin is an endoplasmic reticulum protein involved in the homeostasis of intracellular Ca and other physiological processes. A complementary DNA clone containing the complete coding sequence of Taenia solium calreticulin (TsCRT) was isolated and characterized. Recombinant TsCRT was expressed in bacteria as a 50-kDa protein that specifically bound calcium when tested in a radioassay. The deduced amino acid sequence has 47–50% identity with other reported calreticulins. Poor recognition of TsCRT by human and pig sera with confirmed cysticercosis discourages its use for diagnosis of the disease. However, further characterization and localization studies could provide insights into the role of TsCRT in T. solium physiology and host–parasite interactions.

Parasites have been shown to up- and downregulate host apoptosis, most likely facilitating their ability to successfully establish an infection in the host. It has been demonstrated that pathogens modulate well-established pathways, leading to cell death, including induction of the Fas–FasL system to promote apoptosis. In contrast, it has also been shown that in other instances a decrease in host cell apoptosis results after the upregulation of genes in the Bcl-2 family. The present study examined the ability of Trypanosoma cruzi to modulate expression of host cell genes of the TNFR1 apoptotic pathway. Using microarray technology, gene expression was compared between uninfected BALB/c fibroblasts and T. cruzi–infected BALB/c fibroblasts. After comparing expression patterns between uninfected and T. cruzi–infected BALB/c fibroblasts, it was concluded that genetic expression of genes in the TNFR1 apoptotic pathway is downregulated in T. cruzi–infected cells, indicating that in BALB/c fibroblasts the parasite decreases the expression of genes, leading to host cell apoptosis.

The seroprevalence of Toxoplasma gondii was investigated in wild and captive cetaceans from Japan. Antibodies against T. gondii were examined by both latex agglutination test (LAT) and indirect hemagglutination test (IHAT) for 77 serum or plasma samples obtained from 59 individuals of 6 species, including 2 hybrids. Antibody titers greater than 1:64 in LAT and greater than 1:640 in IHAT, indicative of the presence of T. gondii, were found in 11.9% of 59 individuals. In 7 samples that showed a positive reaction by IHAT, T. gondii titers were examined for each immunoglobulin (Ig) fraction separated by sucrose gradient centrifugation. The antibody peaks in each fraction were divided into 3 types, thought to be a reaction of IgM (type 1), IgG (type 2), and IgM with IgG (type 3). Type 1 was found in serum from a bottle-nosed dolphin (Tursiops truncatus) and a killer whale (Orcinus orca) sampled soon after capture off the Japanese coast in 1988; it was concluded that infection in the wild had occurred less than 15 yr before the study was performed. The prevalence of putative IgM and IgG antibodies from a captive-bred T. truncatus suggested that T. gondii infection also occurred in the aquarium.

A novel laboratory anticestode assay was developed using Hymenolepis diminuta in the hamster. The commercial anticestode compounds, praziquantel, bunamidine, and niclosamide were active against patent infections of Hymenolepis diminuta in golden hamsters (Mesocricetus auratus) when given orally at 3.125, 100, and 200 mg/kg, respectively. The gastrointestinal nematode anthelmintics, cambendazole and mebendazole, were active at 50 mg/kg. Rafoxanide (fasciolicide) was active at 25 mg/kg, the lowest level tested. The coccidiostat, nicarbazin, was active at experimental levels (800 mg/kg and up). The anthelmintic–ectoparasiticide (endectocide), ivermectin, was inactive against the tapeworm at 0.5 mg/kg, as expected.

The susceptibility of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) to the monogenean Discocotyle sagittata in the United Kingdom was assessed by experimental infection of naive fish. One month postinfection with 100 oncomiracidia/host, brown trout harbored significantly lower burdens (27.7 worms/host ± 4.13 SE) than rainbow trout (47.8 worms/host ± 3.90; P = 0.002). This indicates that the consistently lower prevalence and intensity of D. sagittata recorded in naturally infected farmed fishes reflects differences in susceptibility to the parasite. The outcome may be related to the comparatively short-term association of this parasite with rainbow trout (introduced to Britain in the 1880s) compared with the established native host–parasite association.

Toxoplasma gondii is an important pathogen transmitted by food, with raw or undercooked meat as the main foodborne source of toxoplasmosis. In Peru, 2–4 million people have antibodies to T. gondii. It is believed that more than 60 million people in the United States are infected with T. gondii. In this study, the prevalence of T. gondii in pigs from Peru and the United States was determined by Western blot. The presence of IgG antibodies to T. gondii from serum samples was determined. Blood samples were collected from 137 pigs at a slaughterhouse in Lima, Peru, and 152 pigs at a slaughterhouse in Georgia. Of the serum samples collected from swine, 27.7% (n = 38) from Peru and 16.4% (n = 25) from the United States were positive for T. gondii. Swine represent a significant source of human infection with T. gondii in Peru and the United States.

A 3-yr-old secundiparous female ring-tailed lemur presented to the Auburn University Small Animal Clinic with signs of dyspnea, lethargy, and anorexia. The animal died before she could be examined, and a full necropsy was immediately performed. Provisional necropsy findings included moderate pneumonia and hepatopathy. Acute interstitial pneumonia and focal hepatocellular necrosis were confirmed histologically. Lung impression smears, histopathology, electron microscopy, immunohistochemistry, and tissue culture isolation resulted in a diagnosis of acute disseminated Toxoplasma gondii infection, which was confirmed by polymerase chain reaction. The isolate of T. gondii was avirulent for mice and was named AU Tg1 and genetically is type II. The source of the infection remains unclear, but speculation suggests contaminated fruit or blackbirds (Passeriformes: Icteridae) acting as transport hosts for oocysts from nondomestic felids and feral cats on the property.

Toxoplasma gondii tachyzoites were identified in the myocardium of a bald eagle (Haliaeetus leucocephalus) that died of necrotizing myocarditis. The diagnosis was confirmed by immunohistochemical staining with T. gondii–specific polyclonal antibodies. This is a new host record for T. gondii.

By screening a Leishmania braziliensis complementary DNA library with a pool of sera from leishmaniasis patients, the gene coding for L6 ribosomal protein was isolated. The sequence, genomic organization, and transcription of this gene are described in this article. The sequence analysis of the L. braziliensis L6 gene shows a single open reading frame, which codes for a protein of 192 amino acids (aa) with a hypothetical molecular mass of 20.9 kDa. The protein exhibits significant sequence similarity to L6 ribosomal proteins from higher eukaryotes and yeast. Thus, the L. braziliensis L6 protein contains 4 functional motifs, which are located at equivalent positions in other L6 ribosomal proteins described previously. Interestingly, the L6 ribosomal protein from L. braziliensis contains a specific region of 14 aa and a tyrosine kinase motif, which is absent in human and C. elegans L6 protein. The locus coding the L. braziliensis L6 ribosomal protein is formed by 2 gene copies arranged in tandem and located in a chromosome of approximately 0.9 Mb. The genes are actively transcribed as 2 polyadenylated transcripts of approximately 1.15 and 0.85 kb, which differ in their steady-state level and stability.

The tapeworms of the genus Taenia that infect human beings are T. solium, T. saginata and T. saginata asiatica. Taenia solium and T. saginata exhibit unequivocal features that characterize them; in contrast, only recent DNA studies, morphological characteristics, and epidemiological and sanitary aspects indicate that T. saginata asiatica is a subspecies of T. saginata. These 3 tapeworms occur in humans in their adult stage, and the intermediate hosts are pigs for T. solium and T. saginata asiatica and cows for T. saginata. Their identification is crucial considering the migratory increase from Asia to the Western Hemisphere and the fact that these tapeworms coexist in the same environment in Asia; furthermore, it is estimated that movement in both directions across the United States–Mexico border exceeds 200 million persons per yr, and thus, opportunities for acquiring and transporting T. solium infections are multiplied. It is not easy to distinguish among these tapeworms; therefore, a comparative diagram of the 3 parasites is shown in this article, which will facilitate their identification. All morphological features, some of which allow for identification, are clear and can be easily distinguished among the 3 tapeworms.