Triatomines Involved in Domestic and Wild Trypanosoma cruzi Transmission in Concepción, Corrientes, Argentina

Abstract

An entomological and serological survey was performed in three localities of the Department of Concepción, Province of Corrientes, Argentina in 1998 and1999, to Key words: Triatoma infestans -Triatoma sordida -infestation -infection -seroprevalence -ArgentinaIn rural areas of Corrientes Province, Triatoma infestans (Klug 1834) is mainly found indoors and is also present in peridomestic premises (Bar et al. 1992(Bar et al. , 1996b(Bar et al. , 1997.T. sordida (Stål 1859) colonizes wild biotopes (Bar et al. 1996a) as well as artificial ecotopes in peridomestic areas, sometimes coexisting with T. infestans and even established inside a rural house (Bar et al. 1992(Bar et al. , 1996b. In Corrientes city it frequently invades houses and a large colony was captured in an urban ecotope (Bar et al. 1993).Although intradomestic colonies of T. infestans have been eliminated from some areas of Corrientes province, T. sordida may replace it as a domestic vector. Integration of extradomestic triatomines to domestic transmission cycles has been occasionally reported in Minas Gerais, Brazil (Diotaiuti et al. 1993).Anthropic environmental modification, mainly the replacement of natural forest by cultivated land, harvesting of wood and uncontrolled grazing may produce a concentration of wild mammals and triatomines in the peridomicile, generating local transmission cycles of Trypanosoma cruzi. Those foci can provide invading vectors to the domicile that can eventually carry trypanosomes (Wisnivesky-Colli et al. 1993). The peridomicile may represent a transition environment for triatomines coming from the wild and facilitate their domiciliation process (Gajate et al. 1996).An important flood affected Corrientes Province in 1998, as a consequence of the El Niño phenomenon, which made the owners of the dwellings leave them temporarily. Most of the houses were rebuilt afterwards. This entire situation contributed to the increase of the environmental disturbance.In order to increase our knowledge on the ecology of domestic and wild triatomines, an entomological and serological survey was carried out in rural settlements of the Department of Concepción, Corrientes. MATERIALS AND METHODSStudy area -The study area was situated in the localities of Santa Rosa, Colonia Tabay and Colonia Tata Cuá of the Department of Concepción, Corrientes, Argentina (27º to 28ºS and 57º to 58ºW). Biogeographically the area belongs to the oriental district of the Chaco region (Cabrera & Willink 1973).Socioeconomic characteristics -Most of the houses were built with materials obtained from the environment. Wood walls and sheet metal or cardboard roofs were observed in 62.5% of the households, the remainder had mud stick walls and thatched roofs. Similar materials were used to built the storerooms and kitchens.Domestic animals were present in 97% of the households, of which 80.5% were dogs, 55% cats and 53% hens.Peridomestic ecotopes were open structures made with sticks or wood, partially covered or not by a roof, 5-20 m far from the domiciles.The main act...

Ecological characteristics of Triatoma patagonica at the Southern limit of its distribution (Chubut, Argentina)

“…However, although local inhabitants reported some adult bugs flying to houses at night, we did not find any evidence of domestic colonies within our study area. This is distinct from the case with T. sordida and T. guasayana which frequently give rise to small and transient colonies in the domicile (Bar et al 2002).…”

“…This campaign has been successful to control such vector (Schofield & Diaz 1999) but may provide opportunities for other triatomine species to become epidemiologically relevant. In Argentina, the main candidates to occupy the vacant niche left by T. infestans would be the silvatic and peridomestic species of the sordida group: T. sordida Stål (Bar et al 2002), T. guasayana Wygodzinsky & Abalos (Gajate et al 1996), and T. patagonica Del Ponte. The former two species have been intensively studied (Forattini et al 1982, Wisnivesky-Colli et al 1997, Rocha Pires et al 1999, Bar & Wisnivesky-Colli 2001, Vezzani et al 2001), but there is comparatively little information available on the ecology of T. patagonica and current knowledge is based on non-methodical studies.…”

Geometric morphometrics and ecological niche modelling for delimitation of near-sibling triatomine species

“…Triatoma sordida is widely distributed in South America, occurring in open ecoregions with marked dry seasons in Brazil (Cerrado and Caatinga), Bolivia (Bolivian savannahs), Paraguay (the Chaco) and Argentina (humid Chaco) (Lent & Wygodzinsky, 1979; Diotaiuti et al , 1995; Noireau et al , 1997; Bar & Wisnivesky‐Colli, 2001). Currently, T. sordida is the triatomine species captured most often in peridomestic environments in Brazil and Argentina; it is therefore considered as a potential secondary vector of Chagas' disease (Diotaiuti et al , 1998; Bar et al , 2002, 2005, 2009). Triatoma garciabesi was first described from phenotypic variants previously ascribed to T. sordida and collected in the arid areas of northwest Argentina (Carcavallo et al , 1967).…”

Epidemiología de la enfermedad de Chagas, Departamento General Paz, Argentina

“…[1][2][3][4][5]9 En los departamentos de San Luis del Palmar, San Miguel y Empedrado la infestación doméstica por T. infestans es alta, y la infección natural por T. cruzi varía de 23,1 a 38,5%. 1,3,4 En San Luis del Palmar y Empedrado Triatoma sordida coloniza el peridomicilio.…”

“…2,3 Por otra parte, la seroprevalencia global de anticuerpos contra T. cruzi de 959 habitantes analizados en áreas rurales de la Provincia de Corrientes es 26,6% y oscila entre 22,3 y 32,2% en los departamentos investigados. 1,[3][4][5] Generalmente los indicadores entomológicos son empleados con el objeto de evaluar la efectividad de los métodos de control de los vectores de la Enfermedad de Chagas. 15 No obstante, se propone su uso en General Paz para efectuar un diagnóstico de la situación epidemiológica, dado que en el área aún no se realizó una fase de ataque integral.…”