Seroprevalence of Toxoplasma gondii infection in sheep and alpacas (Llama pacos) in Chile.

Serum samples from 408 sheep from different regions of Chile and 447 alpacas (Llama pacos) from the north of the country were tested for Toxoplasma gondii antibodies. The indirect haemagglutination test (IHAT) was used in both species and the indirect immunofluorescence test (IIFT) was also used on the sheep samples in order to compare the performance of the tests in that species. In both tests, titers > or = 1:16 were considered diagnostically significant. Sera from 49 sheep (12%) were positive to T. gondii antibodies by the IHAT. When using the IIFT, 114 sheep sera (28%) were positive. The different results obtained in sheep sera between the tests were significant (p < 0.0001). No differences were observed between geographical locations or sex of the sampled sheep regarding serological detection of T. gondii antibodies in sheep. As expected, adult sheep showed higher T. gondii reactivity than young sheep (p = 0.0008). The corrected prevalence of toxoplasmosis in alpaca was 16.3% (32 positive out of 447). The rather low prevalence in alpacas may be associated with their extensive management as well as the extreme climatic conditions of The Andes which apparently would not be favorable for the transmission of the parasite.

Health status of free-living pigeons in the city of Santiago.

A total of 100 free-living urban pigeons (Columba livia) were captured in the city of Santiago, Chile, in order to evaluate, for the first time, their health status. Negligible antibody titres (1 to 3 log2) were detected in 22% of the birds against a strain of the paramyxovirus (PMV) serotype 1. No pigeons had antibodies against PMV serotype 7 and avian influenza. Salmonella sp. belonging to serogroups B and D were isolated from the intestinal tract of three pigeons (3%). The protozoa Haemoproteus columbae, Plasmodium sp., and Leucocytozoon sp. were not detected in any pigeons. Trichomonas gallinae was detected in 11%, without observation of either clinical signs or gross pathological changes at necropsy. Sixty-seven percent of the birds showed the presence of the chewing lice Columbicola columbae and Campanulotes bidentatus compar, and 1% harboured the mite Laminosioptes cysticola. Seven species of nematodes were identified. The frequency at which each species was detected was; Tetrameres sp. (14%), Capillaria annulata (1%), Capillaria columbae (11%), Capillaria obsignata (1%), Ascaridia columbae (5%), Dispharynx spiralis (2%), and Gongylonema ingluvicola (2%). The class Cestoda, found in one pigeon, was represented by the species Aporina delafondi. No trematodes were detected in the sampled birds.

Immunodiagnosis of fasciolosis in horses and pigs using western blots.

Crude and partially purified somatic (S) and excretory-secretory (ES) antigens of Fasciola hepatica were subjected to Western blot analysis in order to identify polypeptides that would enable specific and sensitive immunodiagnosis of horse and pig fasciolosis to be undertaken. Sera from 20 horses and 20 pigs with natural infections of F. hepatica and the same number of uninfected hosts of each species were tested, together with sera from 2 pigs with Cysticercus cellulosae infections. Using crude S antigens, sera from infected horses and pigs reacted specifically with a wide range of polypeptides of 14-19, 22-30, 35-37 and 42 kDa. Likewise, specific reactivity between polypeptides of 14-17, 22-30 and 40-42 kDa in crude ES antigens and sera from infected horses and pigs was obtained. Against the criteria of high sensitivity and specificity, the 22-30-kDa polypeptides would appear to be the most suitable candidate antigens for use in the immunodiagnosis of fasciolosis in horses and pigs.

[Lyme disease in Chile. Prevalence study in selected groups]. / Enfermedad de Lyme en Chile. Estudio de prevalencia en grupos seleccionados.

BACKGROUND: The prevalence of Lyme disease in Chile is unknown. AIM: To study the existence and epidemiology of Lyme disease in Chile. PATIENTS AND METHODS: One hundred eighteen patients with signs or symptoms suggestive of Lyme disease were studied. Antibodies against Borrelia burgdorferi were measured using ELISA and indirect immunofluorescence screening tests. Positive cases were confirmed with ELISA using a purified antigen and Western Blot analysis. Human biological samples and ticks were cultured in BSK-H medium. RESULTS: Five patients, three with dermatological manifestations and two with facial palsy and other neurological symptoms, had antibodies against Borrelia, measured by ELISA and indirect immunofluorescence. However the presence of IgM antibodies by ELISA using purified antigen, was confirmed in only one case. All sera and cerebrospinal fluids were negative on Western Blot Analysis. No plasma, skin, CSF or thick culture yielded Borrelia CONCLUSIONS: We could not confirm the existence of Lyme disease in Chile. Positive screening with negative confirmatory test suggests false positive non-specific reactivity or that local Borrelia are antigenically different compared to North American strains.

[Prevalence of fascioliasis in humans, horses, pigs, and wild rabbits in 3 Chilean provinces]. / Prevalencia de fascioliasis en humanos, caballos, cerdos y conejos silvestres, en tres provincias de Chile.

This study sought to estimate for the first time the prevalence of fascioliasis among the rural population in the Chilean provinces of Curico, Talca, and Linares, while also determining the disease's prevalence among horses and wild rabbits in Curico and Talca and among pigs in Talca. From January 1986 to December 1990 a randomly selected sample of 5,861 persons in the three provinces was given intradermal, complement-fixation, double-diffusion, and immunoelectrophoresis tests to detect antibody to Fasciola hepatica. In addition, the ELISA test was used in Talca and Linares. Fecal specimens from horses and pigs were inspected for eggs, and the liver and bile ducts of rabbits were examined histopathologically. The overall prevalence of infection among the human subjects was 0.70%, with rates of 0.6% in Curico, 0.75% in Talca, and 0.71% in Linares. The prevalences of infection in horses, rabbits, and pigs were 13.5%, 6.1%, and 20.6%, respectively. It is estimated that some 2,000 people are infected in the study area. It is recommended that rabbits be taken into account in all control programs for this zoonosis.

Helminthiasis and toxoplasmosis among exotic mammals at the Santiago National Zoo.

Parasitologic evaluations of 112 fecal specimens from 292 mammals from the Santiago National Zoo (36 specimens were pooled specimens from greater than or equal to 2 animals) indicated that 51 mammals had protozoa or helminths in their feces. Most of the parasites in the herbivorous species were trichurids and strongylids, whereas most of the parasites in the carnivorous species were ascarids. Coccidia spp and Giardia spp were the most frequently detected protozoans in the mammals evaluated. Of 127 captive mammals serologically evaluated for antibodies against Toxoplasma gondii (indirect hemagglutination test), 35 (27.5%) were positive for T gondii: 7 (46.6%) of 15 carnivores, 24 (25.2%) of 95 artyodactyls, and 4 (22.5%) of 17 nonhuman primates. Antibodies against T gondii also were found in 8 of 10 domestic cats captured within the zoo and in 6 of 13 volunteer zookeepers.

Sarcocystis sp. in guanaco (Lama guanicoe) and effect of temperature on its viability.

The biology of the Sarcocystis sp. that infect guanacoes was studied by feeding the infected meat to dogs, cats, rats and mice. Tissues from guanaco, heavily infected with macrocysts, were fed to these animals and their faeces collected daily and examined for the presence or absence of sporocysts. It was shown that only dogs were suitable definitive hosts. The effect of cooking and freezing on the viability of this protozoan organism was also investigated. Freezing to -18 degrees C and -24 degrees C and cooking were effective for inactivating Sarcocystis in guanaco meat. These methods could therefore be used instead of condemning guanaco carcasses infected with Sarcocystis.

A comparison between the efficacy of thiabendazole and febantel on experimental trichinellosis in rats.

Febantel at a dose level of 5 mg kg-1 had a lethal efficacy of 54.1% against the adult worm and 69.5% against the migrating larvae of Trichinella spiralis in rats. When administered at 15 mg kg-1, it demonstrated lethal effects of 94.4, 92.5 and 74.7% against adult, young and encysted larvae, respectively. Infected rats treated with 300 mg kg-1 died. Thiabendazole had efficiencies of 96.4 and 83.3% against intestinal and migrating early muscle phases, respectively, and was 42% effective against the encysting phase.

Enzyme polymorphism in Fasciola hepatica L.: esterases.

Homogenates of individual adult Fasciola hepatica, collected from bile ducts of sheep, were subjected to isoelectric focusing in polyacrylamide flat-bed gels after which zymograms were made by enzymatic and staining reactions. Seven identifiable isozymes that hydrolyzed alpha-naphthyl acetate were found. These 7 isozymes were identified by their isoelectric points as 5.10, 5.15, 5.25, 5.40, 5.55, 5.65, and 5.75. None of these isozymes was common to all F hepatica examined. Combinations of these isozymes in individual flukes revealed 7 distinct phenotypes, the frequency of which varied between local populations, i.e., populations of flukes obtained from individual sheep of different origin. In addition to these 7 isozymes, there were weak staining bands of enzyme activity, between pH 5.8 and the cathode end of the gels, which could not be accurately identified. The method of isoelectric focusing and zymogram preparation used in the present study did not reveal cholinesterase activity, even though the presence of activity in homogenates was demonstrated by polyacrylamide disc-gel electrophoresis. Strong activity of acid phosphatase between pH 5 and 6 was found, but poor resolution prevented obtaining accurate identification of isozymes. Weak activity with poor resolution of isozymes of alkaline phosphatase was observed between pH 4.4 and 5.75.