An outbreak of acute Chagas's disease in the São Francisco Valley region of Bahia, Brazil: triatomine vectors and animal reservoirs of Trypanosoma cruzi

Abstract

Following reports of an unusually high incidence of acute Chagas's disease and the appearance of large numbers of Triatoma infestans in the southwestern region of the State of Bahia, triatomine bugs (Hemiptera: Reduviidae) and domestic animals in one of the affected communities were surveyed and examined for infection with Trypanosoma cruzi. Triatoma infestans was prevalent in houses and was also found in peridomestic habitats. T. sordida and T. pseudomaculata occupied peridomestic and sylvatic habitats and T. brasiliensis was found only among rocks far from houses. Panstrongylus megistus, formerly present in the region, was not found. Trypanosoma cruzi was detected in 19.5% of Triatoma infestans, 11.5% of T. sordida, 19% of dogs, 29% of cats and 100% of rats examined. A disproportionate number of early instar bugs were infected with Trypanosoma cruzi, suggesting that a rapid increase in the rate of transmission had recently occurred. The history of the domestic triatomine fauna of the region since 1912 is reviewed, and it is proposed that the relatively recent arrival of Triatoma infestans initiated a domestic cycle linked to peridomestic and sylvatic cycles of Trypanosoma cruzi transmission. Increased human mobility, the use of DDT for malaria control, and drought conditions are considered as factors which might have contributed to the outbreak of human infection.

Eco-bio-social research on community-based approaches for Chagas disease vector control in Latin America

“…The additional contribution of house mice and rats to domestic bug infection with T. cruzi , combined with the strong association between T. dimidiata and rodent infestations, are novel findings with clear implications for the design of innovative, integrated vector control strategies. Although synanthropic rodents were infected by T. cruzi in various settings, 41 , 42 their role as (peri)domestic reservoir hosts and the effects of rodent control measures on bug infestation and parasite transmission had not been assessed. The Guatemalan project corroborated large house infestation rates with rodents, 31 and revealed strong links between rats and mice in walls and tiled roofs, infestation with T. dimidiata and T. cruzi infection.…”

Frequent House Invasion of Trypanosoma cruzi-Infected Triatomines in a Suburban Area of Brazil

“…tibiamaculata with T . cruzi and its association with marsupials has been previously demonstrated [ 35 , 36 ].…”

Genomic Changes of Chagas Disease Vector, South America

“…In Uruguay for example, T. infestans appears to have reached some southern communities along the River Plate by 1865 ( 27 ), but it was unknown in northern departments of Uruguay until the early 1900s, when it was apparently imported from southern Brazil by human migrations ( 28 ). This species also seems to have spread across the Sao Francisco River in Bahia during the early 1970s ( 29 ), arriving in the northeastern Brazilian states in the early 1980s ( 30 ). This rapid and recent geographic expansion of T. infestans from Andean countries to the south of the Neotropical region is supported by its relatively low genetic variability, as measured by isoenzymes ( 7 , 26 ) and mitochondrial ( 14 ) and ribosomal DNA sequencing data ( 15 , 31 ).…”