The review discusses the current field status of human and bovine trypanosomiases, and focuses on the molecular basis of innate and acquired control of African trypanosomes in people, cattle, and Cape buffalo.

As a test of the energy limitation hypothesis (ELH), we predicted that temperature would have a significant influence on the infectivity of metacercariae of the digenetic trematode Zygocotyle lunata. Snails infected with Z. lunata were collected from ponds near Crawfordsville, Indiana, isolated at room temperature, and examined for the release of cercariae. Newly encysted metacercariae were collected and incubated 1–30 days at 1 of 5 temperatures (0, 3, 25, 31, 37 C). Twenty-five cysts were fed to each of 5 or 10 mice per treatment group (temperature). At 17 days postinfection, mice were killed and worms were recovered; data were collected on levels of infection in each group and the total body area of each worm. No worms were found in mice fed cysts that had been held at 0 C or 37 C (after 30 days). There were no differences in prevalence, infectivity, or mean intensity among the 3, 25, and 31 C treatments. Infectivity of metacercariae incubated at 37 C for 1 day was significantly greater than in all other treatments, while infectivity of metacercariae in the 37 C/15-day treatment was significantly lower than in all others. Mean body area of worms at 37 C/15 days was significantly greater than at other temperatures, suggesting density-dependent increases in growth. These results, particularly those from the 37 C treatments, are consistent with the ELH; infectivity was lower at high temperatures or when incubated for more time at 1 temperature (fewer energy reserves). It is suggested that microhabitat conditions experienced by metacercariae of Z. lunata could contribute to longer larval life, thus influencing this parasite's temporal dispersal.

Premolt, molting, and postmolt worms of Gnathostoma doloresi (Nematoda: Gnathostomatoidea) recovered from the stomach wall of naturally infected wild boars Sus scrofa leucomystax in Miyazaki, Japan, were examined morphologically. The only molt observed was that from the advanced third-stage to the adult stage. It is strongly suggested that the gnathostomes molt only once in the definitive host.

Relatively little information is available concerning the expression of parasite genes during the liver stage of Plasmodium infection, mostly because of low-level infection of host hepatocytes and the lack of purification techniques for the liver stage parasites. We have determined the optimal dosage of Plasmodium yoelii sporozoite inoculum and routes of inoculation, which are intravenous tail vein and the intrahepatic portal circulation. To determine which route was optimal, BALB/c mice were inoculated via 1 of these routes, and parasitemia was detected by reverse transcription polymerase chain reaction (RT-PCR) detecting both murine β-actin and P. yoelii-specific 28S ribosomal RNA in the liver samples. Murine β-actin was detected after 15 cycles of PCR, and its expression levels did not differ between treatment groups. However, P. yoelii-specific 28S ribosomal RNA gene product was detected after 15 cycles of PCR in animals inoculated via the tail vein but was not detected until 25 cycles in animals inoculated via the intrahepatic portal circulation. Experiments were then performed to identify the smallest inoculum required to initiate a liver stage infection that would yield sufficient parasite RNA for analysis. Inoculation with different doses of sporozoite inocula was followed by RT-PCR on the livers of the inoculated animals. The P. yoelii-specific 28S ribosomal RNA gene product was first detected in both treatment groups after 15 cycles, suggesting that both doses of sporozoite inocula provided relatively the same level of liver infection rate. We also have analyzed infected mouse liver for parasite-specific mRNA, which was detectable as early as 24 hr postinfection.

Life-history theory predicts that hosts should reproduce when first infected by parasites if hosts are capable and if parasites have a lower cost on current than on future reproduction of hosts. We constructed an empirical model to explore fitness of females of the intertidal amphipod Corophium volutator that reproduced soon versus long after infection by the trematode Gynaecotyla adunca. For uninfected females, the optimal time to reproduce was at their maximum body length. However, for females infected by low or high intensities of trematode metacercariae, reproductive potential (realized fecundity) was highest for females that mated immediately after becoming infected. Even after removing a high cost of delaying reproduction for infected amphipods (high likelihood of depredation by sandpipers, which are final hosts of G. adunca), realized fecundity remained highest if reproduction occurred immediately following infection by trematodes. Results from our model support the view that early reproduction of female amphipods following infection by G. adunca is an adaptive life-history response to parasitism.

A portion of mitochondrial 12S rDNA sequences (337–355 base pairs) and 63 morphological characters of 36 hard-tick species belonging to 7 genera were analyzed to determine the phylogenetic relationships among groups and species of Rhipicephalus and between the genera Rhipicephalus and Boophilus. Molecular and morphological data sets were first examined separately. The molecular data were analyzed by maximum parsimony (MP), maximum likelihood, and neighbor-joining distance methods; the morphological data were analyzed by MP. After their level of congruence was evaluated by a partition homogeneity test, all characters were combined and analyzed by MP. The branches of the tree obtained by combining the data sets were better resolved than those of the trees inferred from the separate analyses. Boophilus is monophyletic and arose within Rhipicephalus. Boophilus species clustered with species of the Rhipicephalus evertsi group. Most of the clustering within Rhipicephalus was, however, consistent with previous classifications based on morphological data. Morphological characters were traced on the molecular reconstruction in order to identify characters diagnostic for monophyletic clades. Within the Rhipicephalus sanguineus complex, the sequences of specimens morphologically identified as Rhipicephalus turanicus were characterized by a high level of variability, indicating that R. turanicus-like morphology may cover a spectrum of distinct species.

The effects of testosterone on acquired resistance to ticks, Ixodes ricinus, in their natural rodent hosts (voles, Clethrionomys glareolus, and wood-mice, Apodemus sylvaticus) were investigated by manipulating testosterone levels and exposing the hosts to repeated tick infestations. Testosterone reduced both innate and acquired resistance to tick feeding. During primary infestations, attachment rates were higher on rodents with high testosterone levels than on oil-implanted controls. Successive infestations on voles were accompanied by a decrease in tick feeding success and survival, but this decrease was significantly greater in ticks fed on control voles than in those fed on voles implanted with testosterone. When reduced feeding success had been induced, either by vaccination with tick salivary gland extract or by 4 successive infestations, implantation with testosterone partially reversed the acquired resistance. These effects of testosterone will generate heterogeneities within the rodent population with respect to tick distribution and microparasite transmission. The lowest innate and acquired resistance to tick feeding occurs in that fraction of the host population, i.e., sexually active males, most actively involved in the transmission of both Babesia microti and Borrelia burgdorferi s.l.

The metacestode (larval) stages of the cestode parasites Echinococcus vogeli and E. multilocularis were isolated from the peritoneal cavity of experimentally infected C57BL/6 mice and were cultured in vitro for a period of up to 4 mo under conditions normally applied for the in vitro cultivation of E. multilocularis metacestodes. In contrast to E. multilocularis, E. vogeli did not exhibit extensive exogenous budding and proliferation but increased in size with a final diameter of up to 10 mm. Most metacestodes contained protoscoleces, singly or in groups, either associated with brood capsules or growing directly out of the germinal layer. Each individual metacestode was covered by an acellular translucent laminated layer that was considerably thicker than the laminated layer of E. multilocularis metacestodes. The ultrastructural characteristics, protein content, and carbohydrate composition of the laminated layer of in vitro cultivated E. vogeli and E. multilocularis were assessed using transmission electron microscopy, lectin fluorescence labeling, and lectin blotting assays. The laminated layer of E. vogeli is, as previously described for E. multilocularis metacestodes, largely composed of N-acetyl-β-d-galactosaminyl residues and α- and β-d-galactosyl residues, as well as of the core structure of O-linked carbohydrate chains, N-acetylgalactosamine-β-1,3-galactose. However, in contrast to E. multilocularis, N-linked glycopeptides and α-d-mannosyl and/or glucosyl residues were also associated with the laminated layer of E. vogeli. The laminated layer from both species was isolated from in vitro cultivated metacestodes, and the purified fractions were comparatively analyzed. The protein:carbohydrate ratio (1:1) was similar in both parasites; however, the protein banding pattern obtained by silver staining following sodium dodecyl sulfate polyacrylamide gel electrophoresis suggested intrinsic differences in protein composition. A polyclonal antiserum raised against the E. multilocularis laminated layer and a monoclonal antibody, G11, directed against the major E. multilocularis laminated layer antigen Em2 did not cross-react with E. vogeli, indicating distinct compositional and antigenic differences between these 2 parasites.

The sensory neuronal ultrastructure of the amphids of the infective larva (L3) of Haemonchus contortus was analyzed, compared, and contrasted with that of the first-stage larva (L1). As in L1, each amphid of the L3 is innervated by 12 neurons. Thirteen ciliated dendritic processes of 10 neurons, 3 with double processes, lie in each amphidial channel. The dendritic process of each finger cell neuron ends in a large number of digitiform projections or“fingers,” many more than in the L1. Processes of another pair of specialized neurons, probable homologs of wing cells in Caenorhabditis elegans, extend into the extreme anterior tip of the larva; they are much longer than those in L1. In L3, the neurons exit through the posterior wall of the amphidial chamber individually rather than in a bundle, as in L1. Cell constancy between L1 and L3 was confirmed, and the neurons were individually identified. Significant neuron-specific variations, presumably related to functional differences between the 2 stages were observed. In contrast, species-specific differences are surprisingly small. Haemonchus contortus is closely related to hookworms and has amphidial structure nearly identical to that in hookworms and similar to that in C. elegans, to which it is also closely related.

Otostrongylus circumlitus (Railliet, 1899) from Pacific harbor seals (Phoca vitulina richardsi) and northern elephant seals (Mirounga angustirostris) were examined using morphological and molecular methods to determine whether northern elephant seals along the central California coast are infected by the same species of Otostrongylus as are Pacific harbor seals in the same area. Fixed nematodes were examined and measured using light microscopy. The polymerase chain reaction (PCR) was used to amplify and sequence the second internal transcribed spacer (ITS-2) and D3 expansion (26S) regions of ribosomal DNA of O. circumlitus from Pacific harbor and northern elephant seals. The ITS-2 region was also amplified from Parafilaroides sp. from the Pacific harbor seal, northern elephant seal, and California sea lion (Zalophus californianus) and used for restriction fragment length polymorphism (RFLP) analysis. Morphologically, it was not possible to distinguish O. circumlitus from Pacific harbor and northern elephant seals, and over a consensus length of 443 base pairs (bp) for ITS-2 and 321 bp for D3 the sequences of O. circumlitus from both hosts were identical. With the PCR-RFLP assay, it was possible to distinguish O. circumlitus from Parafilaroides sp. The results suggest that O. circumlitus is the same species in Pacific harbor and northern elephant seals, and molecular methods make it possible to distinguish this nematode from related nematodes.

The maternal inheritance of mitochondrial DNA (mtDNA) in eukaryotic organisms occurs because of the selective destruction of paternal mtDNA molecules that may be present in the zygote. The elimination of sperm mtDNA is less efficient in interspecific crosses, and biparental inheritance of mtDNA has been observed in a variety of species. Because interspecific crosses are likely to be extremely rare in nature, parental inheritance of mtDNA has been deemed of little relevance to population genetics. The mtDNA of the parasitic trematode Schistosoma mansoni was examined for its utility in addressing epidemiological questions related to the transmission and spread of schistosomiasis. Prior to embarking on such experiments, we sought to confirm the mode of inheritance of this molecule using the highly polymorphic mtDNA minisatellite as a marker. In 3 separate crosses, mtDNA apparently identical to paternal DNA was observed in some individuals of the F₂ and F₃ generations. These observations thus suggest the intraspecific paternal inheritance of mtDNA across multiple generations in Schistosoma mansoni.

We investigated levels of Toxoplasma gondii–specific antibodies present in sera, intestinal secretions, and fecal extracts obtained from cats following primary and challenge infections. Antibodies specific to T. gondii tachyzoites, bradyzoites, sporozoites, and enteroepithelial stages were detected by indirect immunofluorescence assay. Enteroepithelial stage–specific antibodies were detected in serum as early as 2 wk after infection, whereas antibodies from intestinal secretions did not appear until 3 wk following infection. The T. gondii–specific IgG and IgA antibodies were present in serum, but only specific IgA antibodies were detected in the intestinal secretions. Serum IgG bound to tachyzoites, bradyzoites, sporozoites, and enteroepithelial stages of T. gondii, whereas serum IgA bound strongly to enteroepithelial stages but only weakly to tachyzoites and bradyzoites. IgA from intestinal secretions bound to antigens on all enteroepithelial stages and the distal tips of sporozoites and bradyzoites but did not bind to tachyzoites. IgA present in fecal extracts also bound to enteroepithelial stages of T. gondii. Toxoplasma gondii infection in cats induces the production of antibodies that bind with all forms of the parasite, including the enteroepithelial stages. Comparison of the staining patterns of T. gondii stages for serum and intestinal secretion IgA indicated differences. Thus, the intestinal antibody immune response may be uniquely focused on the intestinal stages relative to the circulating antibodies, resulting in a compartmentalization of the humoral response.

This study was undertaken to characterize the mucosal response to Cryptosporidium parvum in infected calves that had recovered from diarrhea. Flow cytometric surface phenotypes of lamina propria lymphocyte (LPL) suspensions from infected calves and age-matched controls revealed the presence of a significantly larger proportion of CD25 LPL in infected calves than in controls. Freshly isolated LPL from infected calves expressed more iNOS and interferon (IFN)-γ than did controls. Infected calves excreted IgG₁ and IgG₂ isotype antibodies to C. parvum p23 by the end of the experiment. Moreover, immunohistochemistry of ileal sections revealed the presence of IgG₁ and IgG₂ B lymphocytes in the villi and IgG₁ but not IgG₂ B lymphocytes in continuous Peyer's patch nodules. These data are consistent with the emergence of a type-1–like mucosal immune response in terminal ileal mucosa as calves recover from cryptosporidiosis.

Five persons from 2 families residing at Miyama Town, Mie Prefecture, Japan, ingested fresh raw fish Oncorhynchus sp. on 9 May 1999 that was caught at Owase district in Mie. They all expelled diphyllobothriid cestodes 11–37 days after ingesting the fish. The parasites were morphologically identical to Diphyllobothrium nihonkaiense Yamane et al., 1986. Five plerocercoids were detected from a portion of the fish. Nucleotide sequence of a region of the cytochrome c oxidase subunit I gene of mitochondrial DNA from an adult worm was identical with that from the plerocercoid. The fish was identified as Oncorhynchus masou ishikawae according to the nucleotide sequence of the nuclear ribosomal second internal transcribed spacer region II gene. This is the first record of D. nihonkaiense plerocercoids from O. m. ishikawae.

The objective of this study was to quantify and determine the periodicity in the release of the triactinomyxon (TAM) stage of Myxobolus cerebralis, the causative agent of salmonid whirling disease, by its aquatic oligochaete host Tubifex tubifex. For this, 24 individual T. tubifex (infected as a group at 15 C) were examined daily for the release of M. cerebralis TAMs, and the number of waterborne TAMs released by each worm was quantified. The duration of the infection in these worms was also monitored using a polymerase chain reaction (PCR) diagnostic test. TAMs were first released 74 days postexposure (PE) and continued to be released until 132 days PE. During this period, each worm released on average, 1.5 × 10³ waterborne TAMs 12 times; however, no pattern or periodicity was noted. The results of the PCR diagnostic tests conducted at 5, 7, 9, and 15 mo PE were positive, and the persistent infection was confirmed at 606 days PE (approximately 20 mo) when the remaining worms began releasing TAMs again. Similar results were observed in naturally infected T. tubifex, indicating that these worms remain infected for the duration of their natural lifespan and are capable of shedding viable TAMs, in temporally separate periods. These findings open the possibility of a seasonal periodicity in TAM release by T. tubifex.

Infections with the zoonotic protozoan Toxoplasma gondii during pregnancy can result in severe fetal infections. To investigate the use of pigs as animal models for congenital toxoplasmosis, tachyzoites of 5 T. gondii strains, with low to intermediate virulence in mice, were intravenously inoculated into pregnant minipig gilts. Two strains caused abortions of uninfected fetuses following severe disease of the mothers. One strain caused no disease in the gilts but slightly elevated anti-T. gondii antibodies in 2 of 9 fetuses. One strain produced clinical disease with 4 mummified fetuses and 2 full-term, congenitally infected piglets in 1 gilt and no clinical disease but elevated specific fetal antibodies in both piglets of the other gilt. Infection with the fifth strain (SVS-O14), which was considered apathogenic to both pigs and mice based on the clinical course of this and previous experiments, resulted in significant numbers of congenitally infected piglets, as indicated by production of anti-T. gondii antibodies in all 12 fetuses; the parasite was identified in 3 of these fetuses. This pattern of infection indicates that pigs infected with SVS-O14 (or a similar strain) are relevant animal models for studies of transplacental transmission and pathogenesis of congenital toxoplasmosis.

The distribution of epimastigote forms of Trypanosoma cruzi in the microcirculatory network and the vessel alterations were observed using an intravital microscopy technique. Immediately after intravenous inoculation of 2 × 10⁶ epimastigote suspension into normal mice, parasites were seen as circulating clumps, and their retention at some sites of the endothelium of venules and capillaries was observed. Injection of 2 × 10⁷ and 2 × 10⁸ parasite suspensions induced, respectively, intermittent or total stasis of venules and capillaries, probably via obstruction by clumping. The mobility of epimastigotes in the clumps indicates that parasites were alive in the lumen of vessels. The retention of clumps in the capillaries, although intense, could only be observed when labeled parasites were inoculated. These results suggest that the rapid clearance of epimastigote forms of T. cruzi from the blood circulation of mice may be due to the retention of parasites to the endothelium of venules and capillaries that, in turn, may facilitate phagocytosis. This may be a mechanism by which mice are able to eliminate epimastigote forms from the circulation. These findings are consistent with our previous observations showing that epimastigotes are not lysed by complement activation but are phagocytosed and destroyed by a distinct population of blood cells.

A new species of Rallicola Johnston and Harrison (Phthiraptera: Philopteridae) is described from lice collected from a series of Ruddy Woodcreepers Dendrocincla homochroa (Aves: Dendrocolaptinae) in Campeche, Mexico. Rallicola deckeri is easily recognized by the unique shape of the mesosome in the male and by the pattern of divided sternites on the female.

Nearly complete sequences were obtained from the 18S rDNA genes of Eimeria falciformis (the type species of the genus), Caryospora bigenetica, and Lankesterella minima. Two clones of the rDNA gene from C. bigenetica varied slightly in primary structure. Parsimony-based and maximum likelihood phylogenetic reconstructions with a number of other apicomplexan taxa support 2 major clades within the Eucoccidiorida, i.e., the isosporoid coccidia (consisting of Toxoplasma, Neospora, Isospora [in part], and Sarcocystis spp.) and a second clade containing Lankesterella and Caryospora spp., as well as the eimeriid coccidia (Cyclospora, Isospora [in part], and Eimeria spp.). Our observations suggest that Caryospora spp. may not belong in the family Eimeriidae but rather may be allied with the family Lankesterellidae with which they share molecular and life history similarities. This may be a third lineage of coccidian parasites that has independently evolved a unique heteroxenous transmission strategy.

The generic diagnosis of Alaeuris is emended based on the study and redescription of Alaeuris numidica from the cecum of Testudo graeca collected in Settat, Morocco and of Testudo hermanni collected in Catalonia, Spain. Scanning electron microscopy studies revealed that the papillae previously described as adanal are simple lobes because of the lack of terminal nerves, and that both preanal and postanal papillae are pedunculate. These new findings allowed us to emend the diagnosis of the genus and the species. A list of species of Alaeuris with biogeographic regions and hosts is provided.

Physalopteroides arnoensis n. sp. (Nematoda: Physalopteroidea) from the intestinal tract of the gecko Lepidodactylus lugubris is described and illustrated. Physalopteroides arnoensis is the 18th species to be assigned to the genus and is distinguished from other oriental species by the distribution pattern of caudal papillae of the male: 22 posterior subventral pedunculated papillae; 8 precloacal papillae in symmetrical pairs; 14 postcloacal papillae, 6 papillae immediately postcloacal in symmetrial pairs and remaining 8 papillae asymmetrically placed, 3 on right, 5 on left. Other helminths found include Pharyngodon lepidodactylus, Hedruris hanleyae, Maxvachonia chabaudi, and larvae of Ascarops sp. Our review of Physalopteroides removes all subspecies designations; Physalopteroides minor Caballero, 1969 n. comb is proposed.

Two new nematode species, Beaninema nayaritense n. gen., n. sp. and Rhabdochona xiphophori n. sp., are described on the basis of the specimens recovered from the gall bladder and intestine of 2 fishes, Cichlasoma beani (Jordan) (Cichlidae, Perciformes) and Xiphophorus sp. (Poeciliidae, Cyprinodontiformes), respectively, from Mexico. The monotypic genus Beaninema differs from other rhabdochonid genera mainly in the presence of large conical teeth in the middle of the prostom. Rhabdochona xiphophori is characterized mainly by a unique structure of the prostom (presence of 6 anterior teeth; dorsal and ventral teeth unusually broad, with 2 lateral horns) and the shape of the deirids (bifurcated, with markedly long base).

Of 163 fecal samples collected between March 1997 and February 1999 from the plains vizcacha, Lagostomus maximus (Rodentia: Chinchillidae), 19 (12%) were found to be positive for coccidia. All species are from the genus Eimeria and 2 are described here as new. The third species is consistent with the description of Eimeria chinchillae De Vos and Van der Westhuizen, 1968. Sporulated oocysts of Eimeria lagostomi n. sp. are ellipsoidal to subspheroidal, 35.7 × 30.9 (26–36 × 30–41), with a length:width (L/W) ratio of 1.2 (1.0–1.3), without a micropyle (M) or polar granule (PG), but with an oocyst residuum (OR) comprised of a round, compact mass of many small granules. The sporocysts are lemon-shaped, 14.2 × 10.2 (9–11 × 11–16), with an L/W ratio of 1.4 (1.2–1.7) and have a Stieda body (SB) and sporocyst residuum (SR). Eimeria vizcacha n. sp. has sporulated oocysts that are subspheroidal, 26.4 × 23.4 (21–27 × 23–31), with an L/W ratio of 1.1 (1.1–1.2), lack an M and OR, but have 1–2 PGs. Sporocysts are elongate-ellipsoidal, 14.3–9.0 (8–10 × 13–15), with an L/W ratio of 1.6 (1.4–1.8), lack an SB, but have 2 SR; the first a small mass of granules lying between the sporozoites in the middle or at 1 end, and the second also of many small granules, always at the opposite end. Sporulated oocysts of the E. chinchillae-like organism are ellipsoidal to subspheroidal, 20.7 × 17.5 (15–22 × 17–24) with an L/W ratio of 1.2 (1.0–1.3), lack an M and OR, but have 0–3 PGs. Sporocysts are ellipsoidal, 10.7–6.9 (6–8 × 8–13) with an L/W ratio of 1.55 (1.3–1.8) and have an SB and SR.

Tetrameres (Tetrameres) megaphasmidiata n. sp. is described from the proventriculus of the two-banded plover, Charadrius falklandicus, and the white-rumped sandpiper, Calidris fuscicollis, from Patagonia, Argentina. The new species shares with T. (T.) nouveli, T. (T.) paradisea, T. (T.) prozeskyi, T. paraaraliensis, T. (T.) cladorhynchi, and T. lobybicis the absence of the right spicule and the presence of 4 rows of somatic spines. Tetrameres (T.) megaphasmidiata n. sp. differs from the first 4 species mainly by its longer left spicule. The new species can be distinguished from T. (T.) cladorhynchi by the extension of the lateral alae, the number and arrangement of the caudal papillae, and the absence of polar filaments in the eggs. Tetrameres lobybicis differs from the new species by having shorter rows of dorsal spines and a different number and arrangement of the caudal papillae. This report is the first record of a species of Tetrameres in C. falklandicus and C. fuscicollis.

During May 1997, specimens of 7 species of anurans, that included 5 Phrynohyas venulosa Laurenti, 5 Rana forreri Boulenger, 7 Rana vaillanti Brucchi, 6 Eleutherodactylus fitzingeri Schimdt, 4 Smilisca baudinii Duméril and Bibron, 1 Leptodactylus melanonotus, and 3 Bufo marinus Linneaus, from the Guanacaste Conservation Area, Costa Rica were examined for blood parasites. Their hematozoan fauna included intraerythrocytic and intraleukocytic icosahedral viruses, a rickettsia (Aegyptianella sp.), 2 species of Hepatozoon, Lankesterella minima, 2 unknown species of apicomplexans, 9 morphologically distinct types of trypanosomes, and 2 species of microfilariae. Rana vaillanti, the most aquatic species of frog, harbored the most species of parasites. Recent evidence indicates that morphological changes in the highly pleomorphic trypanosomes of anurans from different geographical regions have not kept pace with biochemical (isozyme) and molecular (DNA sequence) changes. Describing new species based solely on bloodstream trypomastigotes is discouraged. Additional criteria described herein should be applied when naming new species of anuran trypanosomes.

A redescription of the capillariid originally described as Capillaria philippinensis, a pathogenic intestinal parasite of humans, is provided on the basis of specimens collected in humans in the Philippines. The general morphology, particularly the structure of the male caudal end, shows that this species belongs to Paracapillaria Mendonça, 1963 according to the present classification system of capillariids; the species is transferred to Paracapillaria as Paracapillaria philippinensis (Chitwood, Velasquez, and Salazar, 1968) n. comb. Crossicapillaria n. subgen. is proposed to accommodate this species.

Intestinal contents of 41 eastern chipmunks (Tamias striatus) from Armstrong County, Pennsylvania, were examined for the presence of Eimeria spp. Three previously named species were identified: E. lateralis (prevalence = 9%), E. ovata (3%), and E. vilasi (74%); 1 new species, Eimeria tamiensis n. sp. (74%), is described here. This report extends the geographic ranges of the named species into Pennsylvania. Sporulated oocysts of E. tamiensis n. sp. are ovoid and 18.6 × 14.5 (16–23 × 12–17) µm, with no micropyle or residuum. Sporocysts are ellipsoid and 8.6 × 5.4 (7–10 × 4–8) µm, with a Stieda body and granular residuum. Prevalences of E. lateralis and E. vilasi were similar to those reported previously. The differences in prevalences may be due to different life-history strategies of high- and low-prevalence Eimeria species.

One cestode and 3 species of nematodes are recorded from Pseudohydromys murinus and Pseudohydromys occidentalis (Muridae: Hydromyinae), from Papua New Guinea, for the first time. Heterakis fieldingi (Ascaridida: Heterakidea) has previously been known from Australia. Odilia sp. resembles Odilia praeputialis in the orientation of the synlophe and the number and size of ridges but differs in the length of spicule and lack of a praepuce. Protospirura kaindiensis n. sp. (Spirurida: Spiruridae) is readily distinguished from all other members of the genus by the number and arrangement of caudal papillae and the length of the spicules.

As part of a survey of parasites of elasmobranchs in the Gulf of California, a second and final report of the diphyllidean cestodes resulting from the survey is presented. Of 43 species of elasmobranchs examined for parasites, 7 (Rhinobatos productus, Rhinobatos leucorhynchus, Myliobatis californicus, Myliobatis longirostris, Urobatis halleri, Urobatis maculatus, and Rhinoptera steindachneri) were found to host diphyllidean cestodes, all belonging to Echinobothrium. No species of either of the other 2 diphyllidean genera, Ditrachybothridium or Macrobothridium, were discovered. A greater diversity of diphyllideans was found in 1996 than in 1993. Two new species, Echinobothrium hoffmanorum n. sp. and Echinobothrium rayallemangi n. sp. are described from the spiral intestines of U. maculatus and R. leucorhynchus, respectively. Echinobothrium hoffmanorum is unique in its possession of the following combination of characters: 19–21 apical hooks in each dorsoventral group, 12–22 lateral hooklets in each group, 10–17 cephalic peduncle spines per column, 4–8 testes, 4–10 segments and eggs with a single filament. Echinobothrium rayallemangi is unique in its possession of the following combination of characters: 23 apical hooks in each dorsoventral group, 20–23 lateral hooklets in each group, 2–5 cephalic peduncle spines per column, 4–6 testes, and 4–6 segments. These 2 new species, together with Echinobothrium mexicanum and Echinobothrium fautleyae, brings the total number of diphyllideans known from the Gulf of California to 4. The survey of diphyllidean cestodes of the Gulf of California has resulted in a new host record for Echinobothrium for each of the host species mentioned above, with Rhinobatos and Urobatis representing new host genera and Urolophidae a new host family for Echinobothrium.

A new species of Rhinebothrium inhabiting Dasyatis zugei is reported from the southeast coast of China. This is the first report of Rhinebothrium from D. zugei. It represents a new host and a new location. The new species resembles Rhinebothrium corymbum by having a V-shaped ovary. It differs in the fewer loculi and testes numbers, longer bothrium pedicel and cephalic peduncle, larger cirrus pouch and vitelline follicles, and an aspinose peduncle. Rhinebothrium xiamenensis differs from Rhinebothrium ezuti, Rhinebothrium walga, and Rhinebothrium hawaiiensis by having discrete vitelline follicles, fewer loculi, and ovarian shape.

Liposomes consisting of stearylamine (SA) and egg yolk phosphatidylcholine (PC) were studied for their cytotoxic activity against freshly transformed promastigotes and intracellular amastigotes of Leishmania donovani, the causative agent of visceral leishmaniasis. More than 99% of the parasites of strain AG83 were killed within 60 min by treatment with 22 mol% SA-PC liposomes (132 µg/ml total lipids). This was further confirmed by incubating the liposome-treated promastigotes at 22 C for 96 hr. The killing activity of the liposomes progressively decreased with lowering lipid concentration. However, weak cytotoxic activity was still detected at 6.6 µg/ml lipids. Leishmanicidal activity of the liposomes became stronger with increasing SA content but was reduced with the incorporation of cholesterol in the liposomes. A similar cytotoxic effect was observed on other Indian strains of L. donovani, for example PKDL and DD8, as well as on species such as Leishmania donovani S1, Leishmania donovani infantum, Leishmania tropica, Leishmania amazonensis, and Leishmania mexicana. However, freshly transformed promastigotes appeared to be more susceptible than the ones subcultured. The strong leishmanicidal activity of SA-PC liposomes was also demonstrated toward intracellular L. donovani amastigotes. The SA-bearing vesicles could effectively inhibit the growth and multiplication of the parasites within the macrophages. The cytolytic activity of these liposomes on leishmanial parasites and low toxicity on host macrophages may, thus, find application in the therapy of leishmaniasis.

Isometamidium chloride (Samorin) is therapeutic in rainbow trout (Oncorhynchus mykiss) during preclinical and chronic cryptobiosis. However, the toxic mechanism of isometamidium on Cryptobia salmositica has not been elucidated. The objective of the present study was to examine the in vitro effects of isometamidium on C. salmositica. Under in vitro conditions, isometamidium chloride reduced the infectivity of C. salmositica suspended in whole fish blood. It accumulated rapidly in the kinetoplast (within 1 min) and caused disruption and decantenation of kinetoplast DNA. The in vitro cryptobiacidal activity of isometamidium was reduced when parasites were incubated in medium containing serum supplement, suggesting that isometamidium also binds to plasma proteins. Isometamidium altered glycoprotein receptors (epitopes) for antibodies on the surface of C. salmositica and thus protected some of the parasites from lysis by complement-fixing antibodies. In vitro oxygen consumption and carbon dioxide production decreased in drug-exposed C. salmositica, with increased products of glycolysis, i.e., lactate and pyruvate, after exposure to isometamidium. This suggests that some C. salmositica switched from aerobic respiration to glycolysis when the mitochondrion was damaged by isometamidium.

Cryptosporidium parvum oocysts in drinking water have been implicated in outbreaks of diarrheal disease. Current methods for monitoring environmental exposures to C. parvum only account for total number of oocysts without regard for the viability of the parasite. Measurement of oocyst viability, as indicated by an oocyst's ability to excyst, is useful because over time oocysts lose the ability to excyst and become noninfective. Thus, correlating the number of viable oocysts in drinking water with incidence and risk for disease should be more reliable than using the total number of oocysts. We have developed a quantitative assay capable of detecting low numbers of excystable, sporozoite-releasing C. parvum oocysts in turbid water samples. Monoclonal (CP7) and polyclonal antibodies have been developed against a sporozoite antigen released only during excystation or when the oocyst is mechanically disrupted. CP7 is specific for C. parvum and does not react with C. baileyi, C.muris, C. serpentis, Giardia spp., Eimeria spp., or E. nieschulzi. In this assay, oocysts in the test sample are first excysted and then centrifuged. The soluble sporozoite antigen is captured by CP7 attached to a magnetic bead. The captured antigen is then detected by ruthenium-labeled polyclonal antibodies via electrochemiluminescence. The CP7 viability assay can detect as few as 50 viable oocysts in a 1-ml assay sample with a turbidity as high as 200 Nephelometric turbidity units. This sensitive, turbidity-tolerant assay for oocyst viability may permit a better assessment of the disease risk associated with the presence of environmental oocysts.

Cryptosporidium parvum is an intracellular protozoan parasite that causes enteric infection and diarrhea in a wide range of mammalian hosts, including humans and economically important livestock species. There are no effective vaccines or drug treatments available for cryptosporidiosis. Cryptosporidium parvum utilizes a unique metabolic pathway for the synthesis of polyamines, forming agmatine as an intermediary metabolite. We treated infant mice with oral doses of agmatine for 2 days before, the day of, and 5 days following experimental infection with C. parvum. Mice treated with agmatine were significantly less infected with C. parvum than were control mice receiving phosphate-buffered saline. Mice treated with agmatine only on the day of experimental infection with C. parvum were also significantly less infected than were control mice. These data suggest that exogenous agmatine alters the metabolism of C. parvum sufficient to interfere with its ability to colonize the mammalian intestine.

Two experiments were conducted on dogs to evaluate interval to initiation and duration of the first blood meal of Ctenocephalides canis (Curtis). Percentage of fed male and female fleas was calculated for fleas held on dogs for 5, 15, 30, 60 min, 6, and 24 hr. Duration of first blood meal was also measured for individual fleas confined on dogs. When fleas were free in the hair coat, 21.2% had begun blood feeding within 5 min. After 1 hr, 72.5% of fleas had fed. After 6 hr, 95.2% of males and 100% of females had taken a blood meal, and 24 hr after deposition all fleas had fed. There was no significant difference between the 2 sexes. The mean delay between deposition and biting for fleas that began feeding within 15 min was 2 min 52 sec ± 3 min 2 sec for female fleas and 3 min 8 sec ± 2 min 45 sec for males. The mean duration of female and male meals was 5 min 3 sec ± 3 min 41 sec and 6 min 9 sec ± 6 min 8 sec, respectively. There was no significant difference between the 2 sexes. The dog flea took its blood meal on dogs more slowly than the cat flea did on cats; this meal was significantly longer for Ctenocephalides felis felis (Bouché) than for C. canis.

Infectivity of bradyzoites of the VEG strain of Toxoplasma gondii was compared in cats and mice. For this, tissue cysts were separated from brains of infected mice using a Percoll gradient, and bradyzoites were released by incubation in acidic pepsin solution. After filtration through a 3-µm filter, bradyzoites were counted and diluted 10-fold in RPMI tissue culture medium. Dilutions estimated to have 1, 10, 100, and 1,000 bradyzoites were fed to cats and inoculated into mice, orally or subcutaneously (s.c.). Three experiments were performed. In experiment 1, 2 of 2 cats fed 1,000 bradyzoites, 1 of 2 cats fed 100 bradyzoites, 1 of 4 cats fed 10 bradyzoites, and 1 of 4 cats fed 1 bradyzoite shed millions of oocysts; 1,000 bradyzoites were infective to all 4 inoculated mice s.c. but not to 4 mice inoculated orally, and 100 bradyzoites were infective to 2 of 4 mice injected s.c. but not to 4 mice inoculated orally. All 16 mice (8 oral, 8 s.c.) injected with 1 or 10 bradyzoites were negative for T. gondii. In experiment 2, 1 of 4 cats fed 10 counted bradyzoites shed oocysts; the same inocula were not infective to 4 mice injected s.c. In experiment 3, 3 of 4 cats fed 1,000 bradyzoites shed oocysts and the inocula were infective to 10 of 10 mice s.c. and 4 of 10 mice orally; 4 of 4 cats fed 100 bradyzoites shed oocysts and the inocula were infective to 6 of 10 mice s.c. and 0 of 10 mice orally; 10 bradyzoites were not infective to cats and mice. Results indicate that bradyzoites are more infective to cats than to mice, and cats can shed millions of oocysts after ingesting just a few bradyzoites.

Fatal disseminated Toxoplasma gondii infection was diagnosed in 2 captive magpie geese (Anseranas semipalmata) from a zoo in Texas. Both geese died suddenly, without apparent clinical signs. Lesions associated with T. gondii tachyzoites were seen in lungs, pancreas, liver, adrenals, bursa of Fabricius, spleen, brain, and kidneys. Toxoplasmic pneumonia and hepatitis were considered to be the primary cause of death. An unusual feature was the presence of numerous tissue cysts in hepatocytes of both geese. The diagnosis was confirmed immunohistochemically. Antibodies to T. gondii were found in 2 of 11 other geese from the zoo examined using the modified agglutination test. This is the first report of T. gondii infection in magpie geese (Anseranas semipalmata).

In a previous study, when the snail Biomphalaria glabrata was infected with Schistosoma mansoni and maintained on a diet of hen's egg yolk, it produced fully developed cercariae in about one-half the time taken by snails fed Romaine lettuce. Increased lipids were also noted in the snails fed the yolk diet. The purpose of the present study was to further investigate nutritional effects of a high-lipid diet on larval schistosome development and to reexamine the time to cercarial patency in infected snails maintained on either the yolk or lettuce diet and to use high-performance thin-layer chromatography (HPTLC) to analyze the neutral lipids in the digestive gland–gonad complex (DGG) of snails maintained on both diets. Infected snails maintained at 26 C and fed either diet produced fully developed cercariae by 4 wk postinfection (PI). Likewise, infected snails maintained at 23 C and fed either diet produced fully developed cercariae by 6 wk PI. The contention that the yolk diet enhanced the time to cercarial patency was not confirmed. The HPTLC analysis of neutral lipids showed that the DGG of infected snails fed the yolk diet contained significantly greater amounts of free sterols and cholesteryl esters but not triacylglycerols than that of the infected snails fed the lettuce diet.

Two mRNA extraction methods were compared in this study to clarify the discrepancies found between authors regarding the presence of mRNA in inactivated Cryptosporidium parvum oocysts. Cryptosporidium parvum heat shock protein 70 (hsp70) mRNA extraction was performed by using oligo(dT)₂₀-labeled magnetic beads or by incubating oocyst lysates with DNase I. Significant differences in mRNA recovery rates between these 2 techniques were observed when working on inactivated oocysts. We consistently detected hsp70 mRNA in oocysts heated at 60 C for 30 min and oocysts incubated in 10% formalin for 2 hr when using DNase I in the mRNA extraction procedure. In contrast, no mRNA was detected in such oocysts when magnetic beads were used for the mRNA extraction. The selective capture of long poly-A tail mRNA, when using oligo(dT)₂₀-labeled magnetic beads, is proposed in this paper for explaining the discrepancies observed between the two mRNA extraction methods compared in this study. DNA decay in inactivated and aging oocysts makes quantitative polymerase chain reaction a potential alternative technique for assessing C. parvum oocyst viability status in environmental samples.

Serum samples from captive 156 elephants (Elephus maximus indicus) from Thailand were examined for antibodies to Toxoplasma gondii using the modified agglutination test (MAT) and the latex agglutination test (LAT). Antibodies to T. gondii were found in 45.5% of 156 elephants by MAT (≥1:50) and 25.6% of 156 elephants by LAT (≥1:64). This is the first report of T. gondii infection in E. maximus indicus from Asia.