Sylvatic Animals Research Articles

Genetic structure of Trypanosoma cruzi populations from Argentina estimated from enzyme polymorphism

Isolates of Trypanosoma cruzi from human patients, domestic and sylvatic animals and vector insects were obtained in different areas of Argentina. Electrophoretic patterns of enzymes from extracts of 95 isolates were analysed. On the basis of zymograms providing information on 10 loci, 12 zymodemes are described according to their genotypes. Data presented show fixed heterozygosity, absence of segregation of genotypes, significant departures from Hardy-Weinberg equilibrium, and over-represented genotypes. This evidence supports the hypothesis that sexual reproduction is very restricted or absent in this parasite. The proportion of polymorphic loci is 80%. The expected mean heterozygosity per locus (He) is 0.43, while the observed value (Ho) is 0.24. Differences between these values may be explained by accepting a basically clonal structure for T. cruzi. The data matrix of 12 zymodemes using 28 characters was analysed using a Wagner parsimony algorithm. Two equally most parsimonious unrooted trees were generated; both have 39 steps. The results show clusters clearly separated according to the geographical origin of the stocks. There are some indications of some correlations between genetic composition of the parasite and the clinical picture of the infection in human patients.

A large focus of alveolar echinococcosis in central China

Human alveolar echinococcosis (AE) is a rare and highly pathogenic helminthic zoonosis due to infection with the intermediate stage of the small fox tapeworm, Echinococcus multilocularis. Parasite transmission is restricted to northern latitudes, including central and north China, from where few clinical and no detailed community studies have been reported. In August, 1991, 65 (5%) of 1312 people residing in three rural communes of Zhang County, Gansu Province, China were diagnosed as having hepatic AE after mass ultrasound scanning with serological back-up. This represents one of the highest prevalence rates of AE ever recorded. It is also the first time that mass ultrasound scanning and serology have been used together in an AE endemic region. The region was selected one year earlier, when a preliminary serosurvey on 606 unselected people in the same locality resulted in an 8·8% serum antibody positive rate with a 76% rate of confirmation of hepatic AE in 37 individuals who could be followed up in 1991. Seropositivity rates varied for villages between 0 and 20·5%. Overall, females (7·8%) had a significantly greater risk of infection than males (2·5%), especially in the 31-50 age group, a difference which may be related to contact with dogs and dog faeces over many years. Age-specific prevalence of AE increased from 0% in the under-5-year group to 8·2% in those aged 31-50. The youngest case was 11 years and the mean age of diagnosis was 40 years. Adult tapeworms of E multilocularis were identified from the small intestines of 10% of domestic dogs. Sylvatic animal hosts of the parasite have not yet been identified. The high prevalence of human AE in this region of central China is most probably due to semi-domestic transmission of E multilocularis between wild rodents and dogs, together with the poverty and poor hygiene in these rural communities.

Characterization of Trypanosoma cruzi from Argentina by electrophoretic zymograms

Polyacrylamide gel electrophoretic patterns for six enzymes in 73 isolates and 38 clones of Trypanosoma cruzi from different areas of Argentina were classified into 12 zymodemes. The isolates were obtained from human patients with acute, chronic or congenital Chagas' disease, vector insects, domestic and sylvatic animals. Two out of 8 isolates cloned were shown to be heterogeneous. Zymodemes 1 and 12 exhibit widespread geographic distribution; isolates belonging to both zymodemes account for 55% of the total analyzed. The other zymodemes are not widely geographically dispersed. Although there is a clear predominance of zymodeme 1 among asymptomatic patients, the data do not show a clear relationship between particular zymodemes and the clinical picture. The results suggest that the sylvatic and domestic transmission cycles overlap. This remarkable heterogeneity of T. cruzi in Argentina supports the possible multiclonal origin of these parasite populations.

Biochemical resolution of European and African isolates ofTrichinella nelsoni Britov and Boev, 1972

Isoenzyme analysis was used to characterize 47 isolates of Trichinella nelsoni from Europe (EUR) and two from Kenya and Tanzania (AFR). In all, 27 isoenzymes showed polymorphism within the species. The EUR parasites, isolated from domestic, synanthropic, sylvatic animals and man, showed isoenzymatic profiles different from those exhibited by AFR parasites isolated from sylvatic animals. The EUR parasites showed polymorphism due to three isoenzymes, i.e. ME, MPI and PGM. Euclidean distance and a dendrogram were used to evaluate the relationships among isolates. The Euclidean values showed that EUR and AFR genotypes are distant from each other and from the reference strains T. spiralis s.str. and T. pseudospiralis. The genetic data indicate the absence of gene flow between AFR and EUR isolates. The biochemical results suggest the presence of genetic heterogeneity in T. nelsoni and support the existence of a zoogeographical segregation of the two gene pools. The authors propose that as operational labels, code T3 be assigned to EUR isolates and code T7, to AFR isolates.

Population heterogeneity among clones of New World Leishmania species

Cell cloning techniques and schizodeme analysis were used to detect mixtures of subpopulations in Leishmania parasites, isolated from humans and a reservoir host. Clones were obtained by plating promastigotes, at limited dilution, on solid medium. The resultant colonies were analysed by the restriction profile of kinetoplast DNA minicircles (schizodeme analysis). The efficiency of plating was around 40-60%, and subpopulations of different schizodemes, in stocks of Leishmania isolated from 2 cases of human cutaneous leishmaniasis were detected. The presence of different schizodemes in one isolate from a sylvatic animal suggested the possibility of a mixed natural infection.

Distribution of Histoplasma capsulatum in Amazonian wildlife.

In a survey of 296 sylvatic animals captured from virgin forests in the north-eastern and south-western Amazon of Brazil, Histoplasma capsulatum was isolated, via the indirect hamster inoculation method, from the liver and spleen of four common opossums Didelphis marsupialis and two pacas Agouti paca. The infected animals did not show any clinical symptoms or histopathology. The known Amazonian mammalian species with natural histoplasmosis now total five, the previously reported species being the spiny rat Proechimys guyannensis, the two-toed sloth Choloepus didactylus and the nine-banded armadillo Dasypus novemcinctus.

Infrequency of gross skin lesions among Panamanian forest mammals with cutaneous leishmaniasis.

Natural leishmanial infections among feral mammals in the Republic of Panama were studied in relation to gross skin alterations. Three dermatotropic species of Leishmania, L. braziliensis, L. mexicana and L. hertigi, isolated from 230 sylvatic animals of 5 mammalian orders were involved. In 205 (89%) of the cases there were no gross skin alterations. Cryptic infections of all three leishmanial species among wild animals were confirmed by culture and hamster inoculation. This type of infection was always present in the sloths, Choloepus hoffmanni and Bradypus infusatcus, infected with L. braziliensis and in the porcupine, Coendou rothschildi, infected with L. hertigi. Suggestive skin alterations were encountered in 10 (4%) of infected animals. Only 15 (7%) of infected animals exhibited typical leishmanial lesions. It was possible to correlate skin depigmentation with the course of leishmanial infection in one animal, a young kinkajou, Potos flavus.

Erisipelóide de Baker-Rosenbach

O erisipelóide de Baker-Rosenbach, embora assinalado no Brasil há 23, anos, por Sebastião Sampaio, seguido de nove casos estudados em 1951 por Lacaz e Ancona Lopes, não tem sido motivo de publicações posteriores. O A. teve ocasião de estudar seis casos, senão que três foram motivo de trabalho anterior e foram observados em 1953. Os três restantes, um de 1965 e dois de 1967, são aqui relatados. Assinala o A. a ubiquidade do germe, o Erysipelotrix rhusiopathiae e a variedade de condições em que o homem pode infectar-se, especialmente no exercício de determinadas profissões, o que dá à doença, caráter típico de doença profissional. São os operários de fábricas de botões ou em geral os que lidam com ossos, especialmente de porco ou carneiro, os açougueiros, magarefes, salsicheiros etc. São particularmente vulneráveis os que tratam com produtos do mar, pescadores, mercadores de siris, camarões, crustáceos, peixes em geral, pela facilidade com que se podem ferir e adquirir a infecção por picada ocasional. A doença atinge numerosos animais domésticos ou não, com formas clínicas bem definidas no porco (erisipela dos porcos), no carneiro (poliartrite dos carneiros), em animais de corte e de tração, em aves domésticas ou de rapina, ratos e camundongos, além de outros numerosos roedores. Moscas hematófagas e outros insetos têm sido encontrados infectados. Nunca é demais frisar que os produtos do mar são grande fonte de infecção humana. No homem, tem a dcença em geral, caráter benigno e localizado (erisipelóide), podendo em certas circunstâncias assumir característica septicêmica como no porco, produzir endocardite, como no carneiro além de outras formas clínicas e complicações. São resumidos no texto os três casos anteriormente apresentados e bem descritos os três inéditos, que têm história clínica e evolução típicas de erisipelóide. Tratando-se de doença com características tipicamente profissional, há que ser considerada como tal, com respeito às dispensas de serviço ou outras implicações previdenciárias, razão porque mais avulta a necessidade de seu diagnóstico exato e bem documentado, tanto mais que determinadas formas clínicas podem levar à morte. O uso indiscriminado de antibióticos, antes de chegar-se ao diagnóstico, é hábito que deve ser combatido a fim de que se possa melhor avaliar da incidência, em nosso meio.

Human Pasteurelloses, Activation of Interest in Some Latent Problems

(Editor's Note: The following communication is to appear in several medical publications. Attention of readers of Pediatrics is solicited.) Classic consideration of human infections due to members of the genus Pasteurella is concerned with plague (P. pestis) and tularemia (P. tularensis). There have been extensive investigations on plague and tularemia in the U.S. and elsewhere in the world which now provide excellent clinical and epidemiological pictures of these two diseases. However, there are at least four other species of Pasteurella (hemolytica multocida, pneumotropica, and pseudotuberculosis), known human pathogens, for which we have little or no understanding of their clinical importance or epidemiological patterns. Each species has been recovered from a variety of domestic and sylvatic animal reservoirs and each is, to some degree, a veterinary medical problem. Although a measure of the importance of these diseases in domestic animals in the United States is available from U.S. Department of Agriculture statistics, no comparable morbidity figures are reported for man. The occasional case reports that are published indicate, nevertheless, that a problem exists. The question remains, "how extensive is the problem?" The first human infection due to P. multocida to be reported (1913) was a case of puerperal fever. Numerous cases have been reported since, involving respiratory tract infections, appendicitis, bitewound infections, as well as other forms. Until the 1950's cases of P. pseudotuberculosis infection were considered rare, with less than 20 reports of fatal septicemia appearing in the literature. Recently, however, several hundred cases of mesenteric adenitis, often confused with acute appendicitis, have been observed primarily in Europe. In addition, recent cases of erythema nodosum as well as other forms have been described. Furthermore, P. pseudotuberculosis is of considerable importance as a source of diagnostic confusion due to many cultural and biochemical characteristics that this organism shares in common with P. pestis. One case of P. hemolytica infection simulating ulceroglandular tularemia has been reported. Atypical strains of P. hemolytica have been isolated from the respiratory tract and from a case of endocarditis. A number of isolations of P. pneumotropica have been obtained from the respiratory tract. No assessment of the importance of these agents as causes of disease in man in the United States can be made unless clinical and laboratory data can be accumulated. As a step in the right direction, it is suggested that clinical résumés, cultures, and paired sera from any patients, whether typical or atypical cases, be submitted to the U. S. Public Health Service, Communicable Disease Center, San Francisco Field Station, for further study and/or tabulation.

HUMAN PASTEURELLOSES: ACTIVATION OF INTEREST IN SOME LATENT PROBLEMS.

Human Pasteurelloses: Activation of Interest in Some Latent Problems William T. HubbertDVMPh.D. CopyRight https://doi.org/10.2105/AJPH.55.7.962 Published Online: August 29, 2011