Ornithodoros cerradoensis n. sp. (Acari: Argasidae), a member of the Ornithodoros talaje (Guérin-Méneville, 1849) group, parasite of rodents in the Brazilian Savannah

Ornithodoros cerradoensis n. sp. is described from field-collected and laboratory reared nymphs, males, females, and larvae parasitizing the rodents Cavia aperea and Thrichomys sp. in the Brazilian Savannah. This new species is morphologically and genetically related with the Ornithodoros talaje group and can be separated from other Neotropical species using the following combination of characters: larva with 18 pairs of setae on dorsum (seven anterolateral, four central and seven posterolateral), hypostome with median dentition 2/2; adults provided with large mammillae; dorsal disks surrounded by bulked marginal ridges delimiting barely pebbled areas; three disks in the anterolateral file, and median disk not merging with the posteromedian file. Feeding assays in the laboratory demonstrated that (1) larvae of O. cerradoensis are slow-feeders (∼6 days), (2) first nymphal instar (N1) molts to second instar (N2) without feeding, and (3) N2 and third nymphal instar (N3) engorge rapidly (minutes). With the exception of Ornithodoros hasei nymphs that depict flattened bodies, O. cerradoensis N1, N2, and N3 highly resemble homologous instars of other species in O. talaje sensu lato, therefore are not suitable for morphological comparisons within the group. In addition to morphological signature of larvae and adults that separate this new species; results of cross-mating attempts between O. cerradoensis and Ornithodoros guaporensis a morphologically and phylogenetically closely related species that also parasitizes rodents in the Brazilian Savannah; a Principal Component Analysis using larval characters; and a phylogenetic analysis using mitochondrial markers, support O. cerradoensis as an independent lineage within the Ornithodorinae.

Reservoir host competence and the role of domestic and commensal hosts in the transmission of Trypanosoma cruzi

We review the epidemiological role of domestic and commensal hosts of Trypanosoma cruzi using a quantitative approach, and compiled >400 reports on their natural infection. We link the theory underlying simple mathematical models of vector-borne parasite transmission to the types of evidence used for reservoir host identification: mean duration of infectious life; host infection and infectiousness; and host-vector contact. The infectiousness of dogs or cats most frequently exceeded that of humans. The host-feeding patterns of major vectors showed wide variability among and within triatomine species related to their opportunistic behavior and variable ecological, biological and social contexts. The evidence shows that dogs, cats, commensal rodents and domesticated guinea pigs are able to maintain T. cruzi in the absence of any other host species. They play key roles as amplifying hosts and sources of T. cruzi in many (peri)domestic transmission cycles covering a broad diversity of ecoregions, ecotopes and triatomine species: no other domestic animal plays that role. Dogs comply with the desirable attributes of natural sentinels and sometimes were a point of entry of sylvatic parasite strains. The controversies on the role of cats and other hosts illustrate the issues that hamper assessing the relative importance of reservoir hosts on the basis of fragmentary evidence. We provide various study cases of how eco-epidemiological and genetic-marker evidence helped to unravel transmission cycles and identify the implicated hosts. Keeping dogs, cats and rodents out of human sleeping quarters and reducing their exposure to triatomine bugs are predicted to strongly reduce transmission risks.

Effects of blood meal source on food resource use and reproduction in Triatoma patagonica Del Ponte (Hemiptera, Reduviidae)

Triatoma patagonica (Del Ponte, 1929) (Hemiptera-Reduviidae) is a peridomestic vector of Chagas disease that has been frequently found colonizing peridomestic structures in several localities in Argentina. Studying relationships between feeding and reproductive factors is important because these traits regulate population density and define vectorial capacity. Since T. patagonica can circulate among peridomestic structures taking blood from both bird and mammal hosts, we evaluated the extent to which different blood meal sources affect food resource use and reproductive parameters. We used 5(th) instar nymphs and females that fed on either guinea pigs or pigeons to estimate food resource use. We estimated reproductive parameters in adults that fed on these sources. Nymphs and adults showed differences in blood consumption between feeding sources. Females fed on pigeons ingested more blood and needed a higher amount of blood to produce an egg than females fed on guinea pigs. There were no differences in the number of eggs laid and hatched between insects fed on different feeding sources. The higher amount of blood ingested and consumed by T. patagonica fed on pigeons did not translate into higher fecundity or fertility. The lower amount of guinea pig blood ingested was offset by its high nutritional quality.

Periurban Trypanosoma cruzi-infected Triatoma infestans, Arequipa, Peru

Simple interventions may facilitate vector control and prevent periurban transmission of Chagas disease.

In Arequipa, Peru, vectorborne transmission of Chagas disease by Triatoma infestans has become an urban problem. We conducted an entomologic survey in a periurban community of Arequipa to identify risk factors for triatomine infestation and determinants of vector population densities. Of 374 households surveyed, triatomines were collected from 194 (52%), and Trypanosoma cruzi–carrying triatomines were collected from 72 (19.3%). Guinea pig pens were more likely than other animal enclosures to be infested and harbored 2.38× as many triatomines. Stacked brick and adobe enclosures were more likely to have triatomines, while wire mesh enclosures were protected against infestation. In human dwellings, only fully stuccoed rooms were protected against infestation. Spatially, households with triatomines were scattered, while households with T. cruzi–infected triatomines were clustered. Keeping small animals in wire mesh cages could facilitate control of T. infestans in this densely populated urban environment.

Microbiological Monitoring of Guinea Pigs Reared Conventionally at Two Breeding Facilities in Korea

In this study, microbiological monitoring of guinea pigs reared conventionally in two facilities was performed twice in 2004, with a three-month-interval between surveys. This study was based on the recommendations of the FELASA Working Group, with some modifications. In serological tests in the first survey, some animals from facility A showed positive results for Encephalitozoon cuniculi, Sendai virus, pneumonia virus of mice (PVM), and Reovirus-3 (Reo-3); facility B showed a positive result only for E. cuniculi. The results of the second survey were similar to the first, except for the presence of Sendai virus; all animals from the two facilities were Sendai virus-negative in the second experiment. No pathogenic bacteria were cultured in the organs of any of the animals in the first survey. However, in the second survey, Bordetella bronchiseptica was cultured from the lung tissue of two 10-week-old animals from facility A. Chlamydial infection was examined by the Macchiavello method, but no animal showed positive results. Tests using fecal flotation or the KOH wet mount method showed no infection of endoparasites, protozoa, ectoparasites, or dermatophytes in any animal in both surveys. However, in the histopathological examination, an infection of protozoa-like organisms was observed in the cecum of some animals from facility A. The present study revealed that microbiological contamination was present in guinea pigs reared conventionally in two facilities in Korea, suggesting that there is a need to improve environmental conditions in order to eradicate microbial contamination.

Studies on vertical transmission of Trichinella spp. in experimentally infected ferrets (Mustela putorius furo), foxes (Vulpes vulpes), pigs, guinea pigs and mice

Vertical transmission of Trichinella spiralis was evaluated in ferrets (n=21), foxes (n=11), pigs (n=12), guinea pigs (n=16), and mice (n=41). The placental barrier to be crossed by migratory Trichinella larvae varies structurally in different animal species. Ferrets and foxes have an endotheliochorial placenta structure, guinea pigs and mice a haemochorial, and pigs an epitheliochorial placenta. The non-encapsulating Trichinella pseudospiralis larvae have an extended muscle migration prior to entering a muscle cell. To evaluate if T. pseudospiralis was more likely to be transmitted to offspring, an additional group of foxes (n=11) infected with T. pseudospiralis was included. Two different dose levels were used for ferrets, pigs, guinea pigs, and mice. In pigs and guinea pigs, infection was given at different times of the gestation period. Vertical transmission, measured as recovery of muscle larvae in the offspring, was demonstrated in both ferrets groups, in all four guinea pig groups, and in the high dose mouse group, but not in any fox or pig groups.

Lesions in the liver of guinea-pigs infected with the swine lungworm, Metastrongylus apri

Clear spot lesions were formed on the liver surface in guinea-pigs repeatedly infected with swine lungworm, Metastrongylus apri. The largest lesion, measuring 0.25 cm in diameter, was hard and yellow and showed a large granuloma in the lobule. The nematode larva was located at the centre of the lesion. This finding is likely to be an example of erratic parasitism in guinea-pigs with metastrongylidiasis.

Parasite load in guinea pig foetus with real time PCR after maternofoetal transmission of Toxoplasma gondii

Parasite loads of different tissues were assessed in guinea pig foetus after maternal infection. Twelve female guinea pigs were infected with 100 cysts of the 76 K strain of Toxoplasma gondii by the oral route. Inoculation was performed 20 +/- 5 days (G20) or 40 +/- 5 days (G40) after the beginning of gestation. Gestational age was determined by progesterone assay. Maternal and foetal organ samples were taken 60 days after the beginning of gestation. Parasite loads (from placenta, amniotic fluid (AF), cord blood (CB), foetal brain, liver, lung and spleen) were assessed by a real-time PCR quantification using fluorescence resonance energy transfer (FRET) hybridization probes on the Light Cycler. Congenital transmission was proven by the presence of parasites in blood or tissue samples of the foetus in 84.6% (11/13) and 100% (16/16) of cases after inoculation on G20 and G40, respectively. The quantitative analysis of our results after inoculation at G20 and G40 has allowed us to determinate the positive parasitic loads as a function of the origin of the sample and the period of inoculation. The parasite loads expressed as log (parasite/g) were low in AF and CB samples: 1.49 +/- 0.50 and 1.05 +/- 0.10 at G20 and 1.21 +/- 0.36 and 1.20 +/- 0.42 at G40 respectively. In contrast the placenta and the different foetal tissues had higher parasite burdens: 2.89 +/- 0.54 to 5.30 +/- 0.51 at G20 and 2.81 +/- 0.71 to 3.65 +/- 0.59 at G40. All the placentae were positive for parasites even in the two cases with no proven transmission. Real time quantitative PCR using the hybridization probe was a very sensitive and reproducible technique to study the kinetics of congenital toxoplasmosis in the guinea pig model wich is close to that of humans.

[Palaeoparasitological analysis of guinea pig mummies of the Chiribaya culture, Moquegua Valley, Peru]

During several excavations of archeological sites in the Moquegua Valley, Southern Peru, various guinea pig mummies (Cavia aperea f. porcellus) have been discovered. They belong to the Chiribaya Culture (900-1100 AD). The outstanding preservation of the mummified animals gave rise to the idea of a paleoparasitological analysis. In the fur, numerous well preserved ectoparasites (lice, fleas, mites) could be recovered. Generally, ectoparasite remains are rarely found among archeological material. This is the first account of an extensive ectoparasitological analysis of animal mummies in Peru. A modified technique for recovery and preservation of the ectoparasites has been developed.

Life cycle and host specificity of Amblyomma triste (Acari: Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27 degrees C and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed.

Arthropod and helminth parasites of the wild guinea pig, Cavia aperea, from the Andes and the cordillera in Peru, South America

As part of an ongoing research project concerning the diversity and distribution of parasites of Caviidae in South America, 143 wild guinea pigs (Cavia aperea) were collected from 3 localities in the Andean Highlands of Peru. Samples were collected between November 1996 and May 1999 and included representatives of arthropods, nematodes, and trematodes. Seven species of arthropods: Leptopsylla segnis (27.3%), Tiamastus cavicola (6.9%), Gliricola porcelli (55.2%), Hoplopleura alata (6.9%), Polyplax spinulosa (12.6%), Myobia musculi (1.4%), and Eutrombicula bryanti (49.6%); 4 species of nematodes: Capillaria hepatica (6.9%), Graphidioides mazzai (18.8%), Trichuris gracilis (3.5%), and Paraspirudera uncinata (37%); and a single trematode, Fasciola hepatica (4.2%), were identified.

Social structure of the mara (Dolichotis patagonum) as a determinant of gastro-intestinal parasitism

A one-year study of gastro-intestinal parasitism in a free-ranging population of maras at Whipsnade Wild Animal Park, UK, revealed a strong relationship between membership of social units and both intensity and prevalence of infection. The mara, a hystricomorph rodent from southern Argentina, has a social organization including both monogamy and communal denning of the young, an apparently unique combination among mammals. From October 1992 to September 1993, strongyloid parasite loads were estimated from faecal egg counts. A minimum adequate model was fitted to the data using the Genstat statistical package. This showed that family membership had a highly significant effect on the intensity of egg shedding in faeces, and a significant effect on the prevalence of infection. After controlling for both extrinsic environmental and intrinsic demographic factors, homogeneity of infection was greater within than between families and adult pairs.

Host preferences of Triatoma sordida

Triatoma sordida is a widespread vector of Trypanosoma cruzi, living in both sylvatic and domestic habitats. To see if Tri. sordida 'prefers' to feed from avian or mammalian hosts, two experiments were carried out. In the first experiment, in which fifth-instar nymphs were allowed free access to two unrestrained hosts, a guinea-pig and a pigeon, 98% of those feeding fed on the guinea-pig, and the mammalian bloodmeals were generally larger than the avian, with mean weights of 50.9 and 30.2 mg, respectively. In the second experiment, groups of nymphs were exposed to a single host (guinea-pig or pigeon) at two different densities (10 and 30 bugs/host). Whatever the density of the bugs, a much larger proportion of the bugs offered feeds on the guinea-pig took bloodmeals than of those offered the pigeon (55% v. 9%), and the bugs which fed on the mammal again generally took larger bloodmeals (mean weight = 50.9 mg) than the few which fed on the bird (mean weight = 12.8 mg; P < 0.0001). Bug density was found to have a greater effect on the size of the bloodmeals taken from pigeon than on those taken from guinea-pig. Triatoma sordida therefore does not appear to have a marked preference for avian blood; it is probably a generalist species that can invade a variety of habitats to exploit the range of available vertebrate hosts.

The effect of various host species in the feeding performance of immature stages of the tick Hyalomma truncatum (Acari: Ixodidae)

In order to determine the effect of various hosts on the feeding performance of the tick Hyalomma truncatum, were used three mammalian species as hosts. Larvae and nymphs of H. truncatum were fed, under controlled laboratory conditions, on gerbils, guinea-pigs and rabbits. The larvae fed for 4.3 +/- 1.4 days on gerbils, 5.6 +/- 1.3 days on guinea-pigs and 4.7 +/- 1.2 days on rabbits. The mean weights of the larvae which fed in the rabbits, guinea-pigs and gerbils were 0.58 +/- 0.09, 0.46 +/- 0.04 and 0.45 +/- 0.04 mg, respectively. The feeding periods of the nymphs on gerbils, guinea-pigs and rabbits were 7.9 +/- 1.3 and 9.6 +/- 2.2 days respectively. The mean weights of the nymphs which fed on the gerbils, guinea-pigs and rabbits were 22.5 +/- 2.8, 19.7 +/- 1.3 and 15.8 +/- 1.4, respectively. Hyalomma truncatum demonstrated a life cycle of a three-host tick on gerbils and guinea-pigs and of a two-host tick on rabbits. The evolutionary advantage of a two-host cycle over a three-host cycle in metastriate ticks is discussed.

PCR-RFLP analysis of the Cryptosporidium oocyst wall protein (COWP) gene discriminates between C. wrairi and C. parvum, and between C. parvum isolates of human and animal origin

Cryptosporidium wrairi was isolated from guinea pigs during a spontaneous outbreak of cryptosporidiosis. Despite the morphological and antigenic similarities to C. parvum, C. wrairi displayed a different host range and site of infection and may represent a separate species or sub-species. We used the polymerase chain reaction to clone two distinct 550 bp-long DNA fragments, Wc-I and Wc-II, of the gene encoding the Cryptosporidium oocyst wall protein (COWP) of C. wrairi, which showed 98% identity to the C. parvum homologue. Within Wc-I, polymorphic Rsal restriction sites were used to develop a polymerase chain reaction-restriction fragment length polymorphism method able to distinguish C. wrairi from C. parvum and to identify two groups of C. parvum isolates differentially associated with animal and human infections.

[Cytochemical study on the activity of enzymes in trophozoites of Entamoeba histolytica from the cecum of guinea pigs with invasive and non-invasive amebiasis]

Experimental amoebiasis was inflicted on guinea pigs using the PS-2 strain of Entamoeba histolytica. Cytoenzymatic studies were conducted on the trophozoites sampled from the caecum of hosts with non-invasive and invasive amebiasis. The results show higher intensity of the processes of intracellular digestion, transportation, and anaerobic respiration in the amoebae originating from intestine of the host with infective amoebiasis.

Ivermectin treatment of a colony of guineapigs infested with fur mite (Chirodiscoides caviae)

Ivermectin was used for treating a breeding colony of guinea pigs heavily infested with fur mite Chirodiscoides caviae. In preliminary experiments on different dosages and routes of administration, spraying with diluted Ivomec (ivermectin 0.2 mg/ml) as well as applying undiluted ivermectin (10 mg/ml) drops on the fur proved effective and practical. The breeding colony was treated with diluted ivermectin aerosol and retreated two weeks later with undiluted ivermectin drops applied to the coat. After 3 months neither mites nor mite eggs were observed on microscopic examination. Two-and-a-half years later, the guinea pigs are still free of mites.

Cerebrospinal larva migrans due to Baylisascaris procyonis in a guinea pig colony

Four guinea pigs from a colony of approximately 50 animals were examined for progressive neurologic disease of 5 days' duration. Signs of neurologic dysfunction included cachexia, stupor, hyperexcitability, lateral recumbency, and opisthotonos. Results of gross pathologic, microbiologic, and serologic examinations were unremarkable. Histologic examination of cerebral and cerebellar sections revealed multifocal malacia and regions of eosinophilic granulomatous inflammation. Cross-sections of nematode larvae, identified as Baylisascaris sp., most likely B. procyonis, the raccoon ascarid, were seen in the brain of some affected animals. An intact Baylisascaris larva was recovered from a symptomatic animal when cerebral tissue was processed by the Baermann extraction technique. Results of further investigation indicated that wood shavings used for the guinea pigs had been contaminated by raccoon feces, some of which contained numerous B. procyonis eggs. The bedding source for this colony was changed and, to date, no new cases of neurologic disease have been seen. This report emphasizes the potential insidious entrance of B. procyonis into well-managed laboratory animal facilities.

Immunorestorative effect of glucan immunomodulator on guinea pigs with experimental ascariosis

The immunorestorative effect of glucan immunomodulator, combined with porcine immunoglobulin and zinc (GI) on T- and B-lymphocytes and peritoneal macrophage phagocytic ability was studied in guinea pigs with experimental ascariosis (Ascaris suum) after a cyclophosphamide (CY)-evoked immunosuppression. During the migration phase of A. suum infection GI exerted a significant restorative effect on the CY-reduced percentage occurrence of T- and B-cell populations in the mesenteric, mediastinal and hepatic lymph nodes and spleen of A. suum hosts. On the contrary, it did not influence the CY-suppressed phagocytic activity and index of phagocytic activity of the peritoneal macrophages. The protective effect of the GI evaluated by the reduction in the number of migrating ascarid larvae in the lungs of guinea pigs after immunosuppression with CY and administration of GI was 14.46% higher, compared with the suppressed and infected group without administration of GI.

Naturally acquired infections with Leishmania enriettii Muniz and Medina 1948 in guinea-pigs from São Paulo, Brazil

Two domestic guinea-pigs (Cavia porcellus), bought in Pinheros, São Paulo State, Brazil, were taken by their owners to a farm in the rural district of Capão Bonito, close to the Atlantic Forest, São Paulo, where they both developed tumour-like and ulcerating lesions on the ears. The causative agent was identified as Leishmania (L.) enriettii, based on biological characters and isoenzyme profiles. Sources of the parasite in wild mammals, and the possible sandfly vector species are discussed.

Weight gain, hemoglobin uptake, and virus ingestion by Hyalomma truncatum (Acari: Ixodidae) ticks after engorgement on viremic guinea pigs

The ability of guinea pigs to serve as a source of an arbovirus for feeding ticks was examined with Hyalomma truncatum Koch and Venezuelan equine encephalomyelitis virus. Ticks fed on guinea pigs to varying degrees, as indicated by both low and high weight gain and hemoglobin uptake. Pools of larval ticks measured at drop-off with undetectable or very low hemoglobin levels (mean hemoglobin content = 0.05 mg per pool) contained the same amount of virus (> 10(3.0) plaque-forming units [PFU] per pool) as pools of ticks with high hemoglobin levels (mean hemoglobin = 0.15 mg per pool). A group of nymphs that ingested a mean of 0.13 mg of hemoglobin contained the same amount of virus (mean viral titer approximately 10(2.5) PFU) as a group of nymphs that ingested 0.32 mg of hemoglobin. Some adult ticks that ingested < 0.35 mg of hemoglobin contained more virus than adults that ingested > 4.7 mg of hemoglobin.

Acquired resistance of guinea pigs to Dermacentor andersoni mediated by humoral factors

Humoral and cell-mediated immune resistance to tick infestation has been documented in many host-parasite relationships. This study examines passive transfer of resistance to Dermacentor andersoni expressed by recipients of serum pools derived from guinea pigs that had acquired resistance through experimental infestation. Recipients of sera from high titer adult-infested animals expressed resistance evidenced by reduced engorgement weights, histological changes at tick attachment sites, and tick antigen-reactive cytophilic antibody. Recipients of lower titer sera from nymph-infested guinea pigs did not show significant reductions in engorgement weights but did exhibit inflammatory reactions at tick attachment sites similar to those of high titer sera recipients. This study, together with previous findings, suggests that immature instars of D. andersoni may not be as effective as adult ticks in stimulating sufficient humoral responses to convey biological resistance to naive recipients, and it underscores the influence the route of serum administration can have on passive transfer studies.

Feeding nymphs of Hyalomma truncatum (Acari: Ixodidae) on guinea pigs previously exposed to nymphs

The ability of nymphal Hyalomma truncatum Koch to feed on guinea pigs previously exposed to nymphal ticks was studied by measuring the percentage of ticks engorging and molting, their engorged weight, and hemoglobin content. Four guinea pigs were infested with 20, 40, 80, and 200 nymphs, respectively, on three occasions at 21-d intervals, followed by a fourth infestation after another 21-d interval with 100 nymphs. Guinea pigs originally infested with 20 and 80 nymphs were infested a fifth time with 100 nymphs 3 mo after the fourth infestation. Guinea pigs originally infested with 40 and 200 nymphs were infested a fifth time with 100 nymphs 6 mo after the fourth infestation. There was a significant decrease, below infestation I levels, in the number of ticks engorging on each guinea pig during infestations IV and V. Whereas all nymphs molted after infestation I, the percentage of nymphs molting after infestation V ranged from 0 to 34%. For ticks infested on each of the guinea pigs, the percentage molting after infestations III-V were significantly lower than those observed after infestation I. A significant decrease in the mean weight of engorged ticks was observed starting at infestation III. Mean hemoglobin content of ticks declined significantly at infestation II. The response elicited by feeding nymphs appeared to last at least 6 mo.

Effects of heavy metals imission on the cellular immunity of guinea pigs with experimental ascariosis

A study was performed on the short-term effects of industrial heavy metals imission (Hg, Cu, Pb, Zn), collected at 5 km from a mercury-producing plant, on T- and B-lymphocytes and peritoneal macrophages of guinea pigs with experimental ascariosis (Ascaris suum). Administration of the imission for 5 days showed a significant decrease in T- and B-cell population and in macrophage phagocytic ability during the migration phase of Ascaris suum when compared with an infected but untreated group of animals. This was also manifested by an eight-fold increase in the density of migrating ascaris larvae in the lungs. Macrophage metabolic activity in animals given imission was significantly suppressed only until Day 7 post-infection. The most striking decrease in the immunological responses was observed in guinea pigs that were given imission but were not infected.

[A field study of the efficacy of ivermectin in propylene glycol in the treatment of mange in guinea pigs]

The clinical manifestation of mange in a guinea-pig population in Utrecht is discussed. The etiology and the treatment with two subcutaneous injections of ivermectin 0.2 mg/kg with a ten-day interval, is described. A total of 37 guinea-pigs with symptoms and 36 guinea-pig without signs of mange were treated. On the 21st day all previously infested guinea-pigs were free of symptoms. During this study side-effects occurred in 11 of the 73 animals. The most prominent side-effects were a (sub-)dermal necrosis in the younger animals and an inflammation of the cutis in the older animals. The side-effects were probably caused by propylene glycol which was used as a diluent.

Holochilus brasiliensis and nectomys squamipes (Rodentia-Cricetidae) natural hosts of Schistosoma mansoni

After several Brazilian researchers, the author examines the capacity of two species of rodents Cricetidae, Holochilus brasiliensis and Nectomys squamipes, to maintain the biological cycle of Schistosoma mansoni in the field and to be parasite reservoir: (a) the role they are able to play in human endemy; (b) the methods necessary to characterize the population of Schistosoma mansoni related either to man, either to rodents, either to both.

Leishmania braziliensis spp. in the nasal mucosa of guinea pigs inoculated in the tarsi

Two lots of 20 young male guinea pigs were inoculated subcutaneously in the tarsi with 10(4) amastigotes of Leishmania braziliensis braziliensis or L. b. guyanensis to study the susceptibility of this Neotropical hystricomorph rodent the autochthonous parasites. Almost 50% of the animals showed lesions in the inoculation site and had parasitizations that were infective to hamsters, as shown by inoculating homogenates of the dermal lesion, of the spleen, of the liver, and of the nasal mucosa into hamsters at 20, 40, 60, and 120 days after inoculation of the guinea pig. Smears of the above organs showed the presence of amastigotes. Parasites inoculated into the tarsi were detected early in the skin, spleen, and liver of the guinea pig host. Blood cultures made by cardiopuncture on sacrifice of the guinea pigs were uniformly negative. The nasal mucosa of nearly all animals positive in the skin or viscera was invaded early by the parasites, although with greater frequency between 60 and 120 days post-inoculation. The use of this model for the study of mucocutaneous parasitism by L. braziliensis is discussed, together with the phenomena of parasitism at a distance from the inoculation site, the temperature of the body regions affected, and the possible genetic influence on susceptibility of the guinea pig to L. braziliensis.

Hepatic and pulmonary pathology of experimental Fascioloides magna infection in guinea pigs

The guinea pig was used to study the pathology of Fascioloides magna, an important pathogen for sheep. Although flukes migrated freely through various tissues in infected guinea pigs, the most serious lesions occurred in the liver and lungs. The sequential development of lesions indicated that flukes first invaded the quadrate lobe of the liver and subsequently migrated to other liver lobes and tissues. Six weeks post-infection, there was a marked drop in the recovery of flukes from the liver along with a dramatic increase in pulmonary involvement. Much of the hepatic and pulmonary pathology in infected animals was secondary to extensive vascular lesions caused by migrating flukes. In the liver, vascular lesions predominantly involved the portal and hepatic veins. Thrombophlebitis and locally extensive necrosis, resembling infarction, were observed. Vascular lesions in the lungs occurred in the pulmonary arteries leading to thrombosis and haemorrhagic infarction. Discovery of a fluke in a pulmonary artery, along with the pattern of hepatic and pulmonary lesions, suggested that flukes probably used the cardiovascular system as a pathway for dissemination. Death in fluke-infested guinea pigs was most often associated with severe pulmonary lesions. The nature and distribution of fluke-induced lesions observed in this study demonstrate that the guinea pig is a suitable animal model for Fascioloides magna infection in sheep.

Trichuris eggs in animal coprolites dated from 30,000 years ago

Trichuris eggs were found in Kerodon rupestris (Rodentia, Caviidae) coprolites collected in archaeological layers dated from 30,000 yr BP (before present) to 8,450 yr BP. Adult worms and eggs of this genus were not found in a search of living mammals of the region. Results indicate that K. rupestris was a host for an unknown Trichuris species not found in this rodent presently. Climate changes that occurred by 10,000 yr ago in the region could be the cause of its disappearance. The finding of parasites in archaeological material can show the antiquity of host-parasite relationships and parasite losses through time.

Haematological and pathological responses to experimental Trixacarus caviae infection in guinea pigs

Outbred guinea pigs became infected with the mite Trixacarus caviae (Acarina, Sarcoptidae) when introduced into an infected colony. Mite numbers were highest after one month, then fell progressively. Infected guinea pigs developed a neutrophilia, monocytosis, eosinophilia and basophilia. Despite pronounced reactive changes in the superficial lymph nodes, infected guinea pigs developed only a mild dermatitis. In contrast, home bred animals, susceptible to T. caviae acquired many mites and developed a severe chronic dermatitis. Trixacaral manage in guinea pigs offers considerable potential for the study of mite infections in man and animals.

Trypanosoma cruzi: partial prevention of the natural infection of guinea pigs with a killed parasite vaccine

Guinea pigs are natural reservoirs of Chagas' disease. Domestic breeding and local trade of these animals are common practices among andean communities in South America. Infection by Trypanosoma cruzi occurs when the animals live in triatomine-infested houses or yards. The preventive effect of a vaccine consisting of cultured T. cruzi killed by freezing and thawing plus saponin was tested both in mice and in the guinea pig ecosystem. Resistance against T. cruzi challenge in mice was improved by increasing the trypomastigote/epimastigote ratio in live attenuated vaccines but not in killed parasite vaccines. Although the killing of attenuated parasites sharply reduced their immunogenicity for mice, a protective effect against natural T. cruzi infection was detected in guinea pigs. A total of 88 guinea pigs were vaccinated in four intradermal sites on three occasions. Eighty controls received similar inoculations of culture medium plus saponin. All animals were kept in a triatomine-infested yard. Parasitemia was studied with the capillary microhematocrit method. After an exposure time averaging 4 months, natural T. cruzi infection occurred in 55% (44/80) of the controls and in 33% (29/88) of the vaccinated group (P less than 0.01). The number of highly parasitemic guinea pigs was also significantly decreased (6/80 vs 0/88, P less than 0.01). Thus, immunizing protocols which are only partially protective against artificial callenge with T. cruzi may nevertheless constrain the exchange of parasites between natural hosts and vectors.

[Pudica pujoli n. sp. (Nematoda, Trichostrongyloidea), parasite of a Caviidae rodent from Bolivia]

1. Pudica pujoli n. sp. (Heligmonellidae-Pudicinae) is described from a caviid rodent, Microcavia niata in Bolivia. The species can be distinguished from the other species classified in the genus Pudica by the hooked-shape of the spicules' tips and by the length of the vestibule (more three times than length of the sphincter). 2. Définition of the genus Pudica Travassos and Diarriba, 1929, parasitic in echimyid, dasyproctid and myocastorid rodents. A list of the species placed in the genus Pudica is given.

Experimental Haemonchus contortus infections in guinea pigs

Approximately 40% of exsheathed Haemonchus contortus larvae administered to guinea pigs established in the stomach and developed into fourth stage larvae. Most worms were then lost between 5 and 7 days after infection and the guinea pigs were resistant to a second infection. Haemorrhage, oedema and infiltration with inflammatory cells, especially eosinophils, developed in the stomach wall of infected guinea pigs and reactive hyperplastic changes occurred in the gastric lymph node. H. contortus infection of guinea pigs has some potential as a model for study of the pathology, immunology and chemotherapy of gastric nematodiasis.

Trixacarus caviae infection of guinea pigs with genetically determined differences in susceptibility to Trichostrongylus colubriformis infection

Guinea pigs with genetically determined resistance or susceptibility to infection with the nematode parasite Trichostrongylus colubriformis were allowed to become infected with the sarcoptid mite Trixacarus caviae. Compared with nematode-susceptible guinea pigs, nematode-resistant animals had larger populations of mites and developed a more severe dermatitis, with greater mast cell hyperplasia and many more infiltrating eosinophils. The results suggest that animals bred for resistance to one parasite may have greater susceptibility to other parasites.

Field trial of vaccination against American trypanosomiasis (Chagas' disease) in domestic guinea pigs

Domestically bred South American guinea pigs received 3 to 5 immunizing intradermal inocula of 28 X 10(6) live attenuated Trypanosoma cruzi epimastigotes (TCC strain) per kg. These inocula were unable to produce patent infections or to propagate through vectors. Groups of experimental and control guinea pigs were exposed to natural T. cruzi infection in a field yard for periods of up to 551 days. Xenodiagnoses were applied periodically to all animals. This showed that the incidence of natural T. cruzi infection was significantly lowered at various periods post-exposure. The final proportion of infected animals was 39% (20/51) among vaccinees vs. 63% (32/51) among controls (P less than 0.02). The protective effect was exerted particularly upon males and lasted for over a year in one experimental series (infection in 1/7 vaccinees vs. 6/7 controls, P = 0.014). Vaccination reduced vector transmission rates from 38% to 18% (P less than 0.001). These results agree with previous laboratory experiments in showing a partial resistance which does not eliminate residual T. cruzi infection. However, the field work indicates that even this kind of resistance may have epidemiological impact, reducing both the number of reservoirs spreading the disease and the rate of vector transmission.

Cryptosporidiosis in guinea pigs: a retrospective study

Cryptosporidiosis was diagnosed in 81 guinea pigs (Cavia porcellus) from 1979 through 1985 at a research animal diagnostic laboratory. Most of the guinea pigs were juveniles of Hartley stock and originated from 6 commercial laboratory animal suppliers or from one pet store supplier. Common clinical signs reported were failure to gain weight, weight loss, diarrhea, and death. At necropsy, macroscopic findings included emaciation, hyperemia of the small intestine, serosal edema of the cecal wall, and increased fluidity of ingesta throughout the intestines. Oval to round cryptosporidia (1 to 4 microns) were seen microscopically within or on the brush border of mucosal epithelial cells from the duodenum through the cecum. Acute histologic lesions consisted of necrosis and sloughing of enterocytes at the villus tips, inflammation, hyperemia and edema of the lamina propria, and hyperplasia of crypt epithelium. More chronic lesions consisted of marked villus bridging or villus fusion and blunting, metaplasia of the mucosal epithelium, and lymphocytic infiltration of the lamina propria.

Trypanosoma cruzi and Trypanosoma rangeli in Saimiri sciureus from Bolivia and Saguinus mistax from Brazil

Examination of blood films for trypanosomes in primates housed at the Tulane University Delta Regional Primate Research Center showed that 47% (32/68) of the Bolivian Saimiri sciureus and 51% (68/135) of Brazilian Saguinus mistax harbored one or more types: Trypanosoma (Schizotrypanum) cruzi in 6% to 7% and Trypanosoma (Herpetosoma) spp. or Trypanosoma (Megatrypanum) spp. in 39% and 45%, respectively. Trypanosomes were isolated from a sample of the infected monkeys and morphobiological studies were carried out. Both T. cruzi and Trypanosoma rangeli were demonstrated. The transmission of T. rangeli by Rhodnius prolixus, Rhodnius neglectus, and Triatoma infestans was assessed: only R. prolixus transmitted the infection by bite. T. rangeli has not been found previously in Bolivia, nor has any trypanosome been reported previously in Saguinus mistax.

Restriction-endonuclease analysis of DNA from 15 Giardia isolates obtained from humans and animals

The DNA banding pattern of 11 human and four animal isolates (two beaver, one cat, and one guinea pig) of Giardia were compared by using two related techniques. Patterns were compared after endonuclease restriction of DNA followed by agarose gel electrophoresis and ethidium bromide staining and after Southern blot analysis using recombinant plasmids containing Giardia DNA as probes. Two major groups could be distinguished with ethidium bromide staining of eight isolates. Southern blot analysis, however, could distinguish nine different patterns among the 15 isolates studied. One common banding pattern was seen in six isolates (two animal and four human); the remainder of the isolates were unique, with the exception of two identical isolates from sisters. Three isolates (one from a beaver and two from humans) were markedly different from Giardia with the common banding pattern, whereas the other six unique isolates varied moderately. Beavers and other mammals do not seem to possess their own species of Giardia. This methodology introduces a way of distinguishing one species of Giardia isolate from another and promises to be helpful in epidemiological investigations.

[Studies on coccidiosis in guinea pigs. 1. Clinico-pathological observation]

Clinico-pathological and parasitological studies have been performed on spontaneous and experimental coccidiosis in guinea pigs. Among 11,244 Hartley guinea pigs purchased from suppliers during 1968, 410 (3.6%) of the animals had diarrhea due to coccidiosis. The incidence rate was high in the spring and fall with a mortality rate of 14.4 per cent. A particularly high number of fatal cases were found in the spring. In experimentally induced coccidiosis, clinical signs observed were diarrhea, dehydration, weight loss and death. The diarrhea developed in all animals on the eleventh day after infection and continued for one to five days. Food and water intakes were markedly reduced after the appearance of diarrhea, followed by anorexia and dehydration. Correlating with the appearance of diarrhea was a striking drop in body weight of the guinea pigs. Death usually occurred on the third to fifth day after the onset of diarrhea. The mortality rate was 30 per cent. The major macroscopic findings were characterized by a markedly thickened wall from the ascending to the descending colon and gelatinous edema of the mesenterium of the spiral of the ascending colon. Histologically, there was marked hyperplasia of the mucosal epithelium in the colon and numerous coccidia at different stages of development within the mucus membrane. In the advanced stages of the disease, there was degeneration and desquamation of the epithelia, marked edematous change and infiltration of neutrophil leukocytes and lymphocytes into the lamina propria and submucosa, many oocysts in the lumen of the intestine and in the intestinal glands.(ABSTRACT TRUNCATED AT 250 WORDS)