Currently, Chagas' disease control consists mainly of chemical warfare against the insect vector. However, a number of risk factors, such as poor hygiene and clutter, can facilitate the persistence of triatomine breeding sites. Relying on the premise that communities at risk of Chagas have little knowledge about the disease, the authors defined the extent of knowledge that is considered optimal and determined how much is known, on average, by the inhabitants of two areas in Argentina showing different epidemiologic trends. Risk factors in both areas were identified. The optimal extent of knowledge was defined in accordance with 25 "basic concepts" surrounding the disease, and from these questionnaires were constructed for evaluating average knowledge about the disease. Results obtained showed that risk factors were linked primarily with the type of dwelling construction and with clutter, as well as with limited knowledge about the disease. There was little basic knowledge about Chagas, with an inability, for example, to identify the vector and describe the mode of transmission. Increasing people's knowledge about the disease would be an important step in the fight against Chagas and would give the inhabitants of endemic areas a better understanding of their situation as well as the chance to develop behaviors that would allow them to assume responsibility for their own welfare.

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Among the vectors of Chagas disease, Triatoma patagonica is a species in the process of adaptation to the human environment. However, its vector competence is not well known. This study had the aim of evaluating and comparing feeding and defecation patterns among fifth-instar nymphs of Triatoma patagonica and Triatoma infestans that were fed ad libitum. The results showed that nymphs of Triatoma patagonica had a feeding pattern similar to that of Triatoma infestans. Sixty nine percent and 58% of nymphs of Triatoma patagonica and Triatoma infestans, respectively, produced their first defecation within five minutes after being fed. Triatoma patagonica defecated during feeding, with an average time until first defecation that was shorter than that of Triatoma infestans (3.4 and 6.2 min, respectively). The nymphs of Triatoma patagonica were capable of defecating during or immediately after feeding.

Triatoma patagonica (Del Ponte, 1929) (Hemiptera-Reduviidae) is a peridomestic vector of Chagas disease that has been frequently found colonizing peridomestic structures in several localities in Argentina. Studying relationships between feeding and reproductive factors is important because these traits regulate population density and define vectorial capacity. Since T. patagonica can circulate among peridomestic structures taking blood from both bird and mammal hosts, we evaluated the extent to which different blood meal sources affect food resource use and reproductive parameters. We used 5 th instar nymphs and females that fed on either guinea pigs or pigeons to estimate food resource use. We estimated reproductive parameters in adults that fed on these sources. Nymphs and adults showed differences in blood consumption between feeding sources. Females fed on pigeons ingested more blood and needed a higher amount of blood to produce an egg than females fed on guinea pigs. There were no differences in the number of eggs laid and hatched between insects fed on different feeding sources. The higher amount of blood ingested and consumed by T. patagonica fed on pigeons did not translate into higher fecundity or fertility. The lower amount of guinea pig blood ingested was offset by its high nutritional quality. Journal of Vector Ecology 38 (1): 127-133. 2013.

ObjectiveTo study the risk of Trypanosoma cruzi domestic transmission using an entomological index and to explore its relationship with household's characteristics and cultural aspects. Methods There were studied 158 households in an endemic area in Argentina. Each household was classified according to an entomological risk indicator (number of risky bites/ human). A questionnaire was administered to evaluate risk factors among householders. ResultsInfested households showed a wide range of risk values (0 to 5 risky bites/human) with skewed distribution, a high frequency of lower values and few very high risk households. Of all collected Triatoma infestans, 44% had had human blood meals whereas 27% had had dogs or chickens blood meals. Having dogs and birds sharing room with humans increased the risk values. Tidy clean households had contributed significantly to lower risk values as a result of low vector density. The infested households showed a 24.3% correlation between time after insecticide application and the number of vectors. But there was no correlation between the time after insecticide application and T. infestans' infectivity. The statistical analysis showed a high correlation between current values of the entomological risk indicator and Trypanosoma cruzi seroprevalence in children. ConclusionsThe risk of T. cruzi domestic transmission assessed using an entomological index show a correlation with children seroprevalence for Chagas' disease and householders' habits. Resumen Objetivo

Among the vectors of Chagas disease, (Carcavallo et al. 1999).It was found naturally infected by Trypanosoma cruzi (Chagas 1909) (Lent & Wygodzinsky 1979) and in Río Colorado (province of Río Negro) it was the only peridomestic species found in houses both in urban and suburban areas (Ferrero et al. 1999). These last records, added to the permanence in the peridomicile, point the need to determine how competent T. patagonica is as a vector of Chagas disease, especially in aspects related to feeding and defaecation.These two processes (feeding and defaecation) have been thoroughly analyzed in triatomines as they are closely related to the development and transmission of T. cruzi (Mello 1980, Kirk & Schofield 1987, Trumper & Gorla 1991, Crocco & Catalá 1996. These processes are well known in domestic species like T. infestans (Klug, 1934) (Forattini et al. 1982, Friend & Smith 1985, Trumper & Gorla 1991 and Rhodnius prolixus (Stal, 1859) (Forattini et al. 1982, Friend & Smith 1985. Nevertheless, very little is known about peridomestic species including T. patagonica (Del Ponte, 1929) about which only facts relating to its life cycle and habitats are known (Martínez et al. 1985, Carcavallo et al. 1998.From an epidemiological point of view, it is very important to have knowledge related to feeding and defaecation, the aim of this work is to evaluate the feeding pattern and the defaecation behaviour in adults of T. patagonica. MATERIALS AND METHODSThis work was carried out with 29 adult females of T. patagonica. These were obtained as fifth instar nymphs by the Servicio Nacional de Chagas (Argentina). The insects were maintained under laboratory conditions at 26ºC ± 1ºC and at 60-70% humidity. After moulting, the insects were weighed and marked with acryllic paint following predetermined codes and were starved for 15 days (after moulting). After fasting, they were fed ad libitum on a restrained pigeon. For each feeding the following variables were determinated:Blood meal size -This was determined by the difference in weight before and after feeding.Feeding time -This was obtained by recording the time (in minutes) since the rostrum of the insect came into contact with the skin of the host until it detached itself.Number of defaecations during feeding -This was registered by direct observation of the insect while feeding on the pigeon.Number of defaecations emitted during the first 30 min after feeding -This was registered by direct observation of the insect while it was on the host and during 30 min after feeding.All weights were measured using a Mettler Balance with a precision of 0.001 mg. The t-test for samples with dependent variables for comparing variables of the different groups, was used as statistic treatment. To verify the homogeneity of variance the Levenne test was used (Ferrán Aranaz 2001). RESULTSIn Table I, the variables analyzed concerning feeding behaviour of females of T. patagonica are shown. The data were obtained from the repletion feeding of 29 females of T. patagonica, the average time rec...