Abstract
Peri-urban infestations with triatomine bugs, their sources and their dynamics have rarely been investigated. Here, we corroborated the reported occurrence of Triatoma infestans in a peri-urban area and in neighbouring rural houses in Pampa del Indio, in the Argentine Chaco, and identified its putative sources using spatial analysis and demographic questionnaires. Peri-urban householders reported that 10% of their premises had triatomines, whereas T. infestans was collected by timed manual searches or community-based surveillance in only nine (3%) houses. Trypanosoma cruzi-infected T. infestans and Triatoma sordida were collected indoors only in peri-urban houses and were infected with TcV and TcI, respectively. The triatomines fed on chickens, cats and humans. Peri-urban infestations were most frequent in a squatter settlement and particularly within the recently built mud houses of rural immigrants, with large-sized households, more dogs and cats and more crowding. Several of the observed infestations were most likely associated with passive bug transport from other sources and with active bug dispersal from neighbouring foci. Thus, the households in the squatter settlement were at a greater risk of bug invasion and colonisation. In sum, the incipient process of domestic colonisation and transmission, along with persistent rural-to-urban migratory flows and unplanned urbanisation, indicate the need for active vector surveillance and control actions at the peri-urban interface of the Gran Chaco.
Highlights
Vector-borne transmission of T. cruzi has been closely linked to rural poverty and substandard housing quality
As part of a longitudinal research and control project in rural areas of the Argentine Chaco, we reported a high prevalence of house infestation with T. infestans (40%) associated with moderate levels of pyrethroid resistance, which caused vector control failures in a rural section of the municipality of Pampa del Indio (Gurevitz et al 2012)
Distribution of infested houses and prevalence of Trypanosoma cruzi infection in Triatoma infestans and Triatoma sordida determined by direct microscopic observation (MO) and kDNA-polymerase chain reaction (PCR) according to survey date and collection method in a peri-urban area and adjacent rural houses of Pampa del Indio, Chaco, Argentina
Summary
Vector-borne transmission of T. cruzi has been closely linked to rural poverty and substandard housing quality. Between 2008-2013, vector control interventions were scaled up in all rural areas of the municipality until achieving a similar degree of control (RE Gürtler et al, unpublished observations) During this period, the residents of emerging peri-urban areas in Pampa del Indio occasionally provided anecdotal reports of house infestation with triatomine bugs and records at the local hospital indicated the frequent occurrence of T. cruzi-seropositive residents in local peri-urban areas. The residents of emerging peri-urban areas in Pampa del Indio occasionally provided anecdotal reports of house infestation with triatomine bugs and records at the local hospital indicated the frequent occurrence of T. cruzi-seropositive residents in local peri-urban areas Based on this information and the success of previous vector control actions, in 2011, local health authorities proposed conducting blanket insecticide spraying of a peri-urban area (Parque Industrial) that had recently sprawled. Our work provides a case study of ongoing house reinfestation with a major vector species at the interface between peri-urban and rural areas
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