Molecular epidemiology and ecosystem approach of the reinfestation process by Triatoma infestans in rural communities of the Paraguayan Chaco

ANTONIETA ROJAS-DE-ARIAS, MIRIAM ROLON, MARÍA CELESTE VEGA, ANA GÓMEZ, FABIOLA ROMÁN, HUMBERTO SÁNCHEZ, CYNTHIA ACOSTA, CESIA VILLALBA, CECERE MC, ELLEN DOTSON4, PAULA MARCET4.

Bogotá

Congreso; XX Congreso Latinoamericano de Parasitología. XV Congreso Colombiano de Parasitología y Medicina Tropical; 2011

Study area: Four villages belonging to the indigenous territory of the Central Chaco were surveyed from March 2008 to November 2009. The base line survey carried out in 325 dwellings showed an indoor infestation rate with T. infestans around 36% and a colonization index of 62.7%. Peridomestic house infestation was 37.5% (12/32) finding only Triatoma sordida and all foci were chicken coops. No T. infestans was collected in the peridomestic area. Table 1. Factors associated with the occurrence of T. infestans infestation at the baseline survey Variable Odds Ratio 95% CI p Unplastered internal walls 1.06 0.41 2.73 0.90 Non-resistant house materials in all components 1.34 0.58 3.10 0.50 House > 5 years 1.01 1.00 1.01 0.25 Number of rooms 1.04 0.94 1.15 0.41 Animals entering the house 0.60 0.18 2.03 0.41 Presence of animals 2.18 0.71 6.71 0.17 Risks factor analysis for house infestation: Contrary to expectations. Risk factors were not associated with T. infestans house infestation (Table 1). Spatial analysis of bug abundance: After the first insecticide spraying each house was re-inspected for the presence of triatomine bugs in August 2008, and every three months afterwards from November 2008 to November 2009. Among the 332 houses analyzed, 6.3% reached a significant range of aggregation (12700-13400m), and all of them belonged to the 12 de Junio village. During the first year post-spraying The cumulative number of T. infestans per house in 12 de Junio, the location of the sylvatic foci and two suspected foci within of this village, did not show any spatial relationship with the pattern of house reinfestation. In Campo largo village, two significant focal clusters of the cumulative number of T. infestans after one year post-spraying were observed, showing several infested houses within the influence areas of these two focal clusters (Table 2). T. cruzi infection and lineage identification: A total of 57 domestic T. infestans collected at the baseline survey that were microscopically positive for T. cruzi were cultured, and 46 isolates were successfully obtained. Among reinfestant triatomines, 5 isolates were achieved. For identification of different T. cruzi lineages and sublineages, a combination of four PCR reactions was used: D7 of 24sRNA, 18SrRNA, miniexon and PCR-RFLP HSP60. Only lineage 2 (TII) was isolated from T. infestans., T. cruzi IIe (TCVI) predominated in 12 de Junio (n=23), whereas T. cruzi IId (TCV) was the only one detected in Campo Alegre (n=22). In Campo Largo we obtained 6 isolations of TCVand one of TC2b (TCIV) from a female T. infestans captured indoors.