ABSTRACT
This study aimed at identifying the ecological characteristics of Triatoma patagonica Del Ponte 1929 (Hemiptera: Reduviidae) and evaluating the epidemiological importance of this species at its southernmost distribution limit. We carried out two surveys in the Province of Chubut, in summer and in spring, 1998. In each survey, we interviewed local health care agents for triatomine recognition and reports of the bugs, followed by entomological searches in houses and peridomestic and silvatic biotopes. The presence of T. patagonica was confirmed in two of the five localities indicated by interview. In agreement with previous studies, all these positive localities were east of the 11ºC isotherm, within the Monte phytogeographic province. Triatomine abundance and infestation levels (in peridomiciles and peridomestic biotopes) were higher in summer than in spring, possibly reflecting adverse environmental conditions such as flood and cold winter weather. In the silvatic environment, we found three adult bugs under rocks in summer. In peridomestic sites bugs were only found associated with chickens, which were also the only blood meal source identified. Infection by Trypanosoma cruzi was not detected. We conclude that T. patagonica at its southernmost distribution limit does not represent a risk to public health due to its low abundance, lack of association with humans, and absence of T. cruzi infection.
Subject(s)
Animals , Female , Humans , Male , Insect Vectors , Triatoma , Argentina , Ecosystem , Feeding Behavior , Housing , Insect Vectors , Population Density , Seasons , TriatomaABSTRACT
We report the first evidence of natural infection of Lymnaea columella with Fasciola hepatica in Argentina. A sample of 601 snails was collected in May 2003 in northeastern Corrientes, a province bounded on the north by Paraguay, on the east by Brazil and on the southeast by Uruguay. Among 500 examined snails, 44 (8.8 percent) were exclusively infected with F. hepatica. Parasite identification was based on morphological features of cercariae from snails, and of eggs and adult flukes from Wistar rats. We discuss the events suggesting that an enzootic transmission cycle of F. hepatica has been recently established in northeastern Corrientes.
Subject(s)
Animals , Rats , Fasciola hepatica , Lymnaea , Argentina , Rats, WistarABSTRACT
Triatoma guasayana is a silvatic triatomine species distributed in Argentina, Bolivia and Paraguay. The study was performed in a secondary forest of Santiago del Estero, Argentina. The abundance of T. guasayana was evaluated by census in the following wild biotopes: quimiles (Opuntia quimilo), chaguares (dry bromeliads), logs and underground burrows. Ten biotopes of each type were dismantled in winter (August) and another 40 in summer (January); all fauna was recorded. The biotopes most infested by T. guasayana were quimiles (65 percent), followed by chaguares (55 percent), and logs (25 percent). Quimiles and chaguares were infested in both seasons, whereas logs were positive only in summer and burrows were never infested. Infestation and abundance were higher in summer than in winter. The biotope structure is a key factor for T. guasayana colonization. The larger number of refuges, the constant presence of blood sources and suitable inner microclimatic conditions offered by quimiles may favour the persistence of T. guasayana colonies. The richness of invertebrate fauna per type of biotope was ranked in the same order as that of T. guasayana, suggesting similar microhabitat requirements for all studied arthropods
Subject(s)
Animals , Male , Female , Ecology , Insect Vectors , Trees , Triatoma , Argentina , Seasons , WoodABSTRACT
Triatoma sordida and T. guasayana are competent Trypanosoma cruzi vectors, with overlapping distribution areas in Argentina. Both species are morphologically similar, and their immature stages are hard to discriminate. Cytogenetic studies in the genus Triatoma reveal scarce karyotypic variations, being 2n=20 + XY the most frequent diploid number in males. In the present work the meiotic behaviour of different Argentinian populations of T. sordida and T. guasayana has been analyzed; the meiotic karyotype of both species has also been compared. The species differ in total chromosome area and the relative area of the sex chromosomes. These meiotic karyotypic differences constitute an additional tool for the taxonomic characterization of T. sordida and T. guasayana. The analysis of an interpopulation hybrid of T. sordida (Brazil x Argentina) reveals a regular meiotic behaviour, despite the presence of heteromorphic bivalents. Our observations support the hypothesis that karyotype variatons through the gain or loss of heterochromatin can not be considered as a primary mechanism of reproductive isolation in Triatoma.
Subject(s)
Animals , Meiosis , Triatoma/genetics , Argentina , BrazilABSTRACT
Determina a associaçäo entre Triatoma infestans, aves domésticas e o homem no povoado de Trindad, Santiago del Estero, Argentina. Para coletar triatomíneos foram realizadas quatro amostragens no peridomícilio de seis casas, utilizando-se o método de captura hora/homem (dezembro de 1991 a outubro de 1992). Os anexos foram classificados em antrópicos (onde o homem realiza atividades cotidianas) e näo antrópicos. Determina o perfil alimentar dos barbeiros. De um total de 134 ecótopos investigados, 21 por cento tinham T infestans; 22 por cento possuiam aves domésticas; e 54 por cento eram antrópicos. Em 25 por cento destes eótopos foram encontrados aves e T. infestans simultaneamente. As aves foram os únicos animais domésticos associados com o T. infestans, sendo que esta relaçäo só ocorreu nos ecótopos antrópicos. A proporçäo de ingestas em aves (61/146) foi altamente significativa. Em Trinidad näo há galinheiros, utilizando-se, assim, os anexos antrópicos do peridomicilio como local para se construir os ninhos para as aves. Tanto pelos elementos usados na preparaçäo dos ninhos como pelo uso posterior dos mesmos, poder-se-ia estabelecer um fluxo periódico de barbeiros do intradomicilio para o transporte passivo. Esta relaçäo estreita Triatoma infestans, aves domésticas e o homem, encontrada nos ecótopos antrópicos, onde também existem outros reservatórios de T. cruzi, como os cäes, favorece a manutençäo de colônias de barbeiros domiciliares e a transmissäo da doença de Chagas ao homem.
Subject(s)
Humans , Animals , Poultry , Triatoma , Chagas DiseaseABSTRACT
Flight activity and invasion of houses by Triatoma sordida and T. guasayana were studied in the Province of Santiago del Estero, Argentina. Spontaneous findings of both species in houses were recorded from 1982 to 1989. Light trap collections were performed in 1982, 1983 and 1984, at the woods surrounding the settlements of Amamá (43 houses) and Trinidad (19 houses). Most of the 101 triatomines collected, were unfed and negative for Trypanosoma cruzi. T. guasayana predominated over T. sordida, and both appeared on the lighted screens between 19-31 min (mean 24) after dusk and the catch time was 30-45 min. Although entomological evaluation of 41 houses at Amamá performed in September 1985, just before insecticidal spraying, showed that Triatoma infestans predominated, adults of T. guasayana were collected in sleeping places, in 7 houses (17%). Most triatomines invading houses from then up to 1990 were flying T. guasayana (20/27) and females outnumbered males. Three non infected T. guasayana females were fed on man and two T. guasayana males positive for "T. cruzi like" trypanosomes were unfed. Therefore, visiting hungry adults could transmit T. cruzi to people and introduce wild parasites to the domestic cycle. T. guasayana stands as the main potential substitute of T. infestans in the studied area, and it might play there the same role as T. sordida in Brazil