The importance of the opossum (Didelphis albiventris) as a reservoir for Trypanosoma cruzi in Bambuí, Minas Gerais state

Abstract

In a survey realized on the sylvatic and peridomestic environments at Bambuí county, Minas Gerais State, 44 (37.9%) out of 116 opossums (Didelphis albiventris) captured were found to be naturally infected with Trypanosoma cruzi. One hundred and forty three parasite samples were obtained from 43 infected opossums using simultaneously hemoculture, xenodiagnosis (Triatoma infestans, Panstrongylus megistus and Rhodnius neglectus) and examination of anal glands contents. The parasite samples were characterized according to six isoenzyme patterns. All samples, independently of the method of isolation, presented an isoenzyme pattern similar to the standard T. cruzi Z1, showing that either xenodiagnosis or hemoculture can used without selecting parasite subpopulation from naturally infected opossums. Previous isoenzyme patterns reported for human T. cruzi isolates from the same region were completely different. This isoenzyme dissimilarity between sylvatic and domiciliar environments suggests the existence of two independent T. cruzi transmission cycles in Bambuí. The epidemiological implications of these results are discussed.

Characterization of Trypanosoma cruzi Strains Isolated from Chronic Chagasic Patients, Triatomines and Opossums Naturally Infected from the State of Rio Grande do Sul, Brazil

“…Zymodeme Z1 parasites was the only zymodeme found in a large number of T. cruzi strains isolated from D. albiventris from Bambuí, Minas Gerais and from D. marsupialis from the State of Santa Catarina, respectively, endemic and non endemic areas of Chagas' disease in Brazil (Fernandes et al 1991, Steindel 1993. In contrast, T. cruzi zymodeme Z2 was isolated from 2 naturally infected D. albiventris from Rio Grande do Sul.…”

Serological survey for Leishmania sp. infection in wild animals from the municipality of Maringá, Paraná state, Brazil

“…Polymerase chain reaction of flagellates with Leishmania (Viannia) primers revealed no results (data not shown). Flagellates were not identified, but these species were found to be naturally infected by Trypanosoma cruzi (41,42).…”

Probability of Trypanosoma cruzi transmission by Triatoma infestans (Hemiptera: Reduviidae) to the opossum Didelphis albiventris (Marsupialia: Didelphidae).

“…Table 2 shows the experimental results in terms of the variables X, W, and Y. A contingency test using the ''biting'' and predation frequencies of Table 2 showed that the ''bit- Probability that a ''bite'' will infect an opossum p 2 Probability that a bug that has been eaten by an opossum will infect it, either because it had ''bitten'' the opossum previously, or as a direct result of having been ingested p 3 Probability that if a bug is ingested it will infect the opossum exclusively because of the ingestion itself p 4 Probability that an ingested bug might have ''bitten'' the opossum before being eaten p 5 Probability that, faced with a triatomine for 23 hr, the opossum will eat it p 6 Probability that, exposed for 23 hr to one infected triatomine, the opossum will become infected * For definition of a ''bite,'' see Materials and Methods. The experimental results showed that p 5 ϭ 0.254 (33 of 130 triatomines were eaten, see Table 2).…”

“…In all countries where the role of opossums as reservoirs of Trypanosoma cruzi has been studied, a relatively high prevalence of 20-100% was found. [1][2][3][4][5][6][7][8] In Argentina, Didelphis albiventris is the most important wild reservoir of T. cruzi, with an annual prevalence in Santiago del Estero that varied between 29% and 50% (Schweigmann N, unpublished data). This prevalence of this host coexists with a very low triatomine (particularly for Triatoma guasayana) infection, sometimes less than 1%.…”