Rethinking the old hypothesis that new housing construction has an impact on the vector control of Triatoma infestans: A metapopulation analysis

Triatoma infestans (Hemiptera: Reduviidae) is a hematophagous insect, vector of the parasite Trypanosoma cruzi, etiological agent of the Chagas disease. In the south of La Rioja, Argentina, the persistent infestation by triatomines encouraged a program of construction of brand new dwellings in rural areas since 2008, to reduce infestation. According to the metapopulation theory approach, each dwelling was considered to be a patch with different degrees of quality concerning the availability of shelters for T. infestans. Accordingly, brand new dwellings (BNDs) are considered of lower quality for triatomines, compared to traditional dwellings (TDs). The main objective of this study was to analyse the occupancy in patches of different quality and to evaluate the effect of BNDs in the control of T. infestans. 397 patches from three departments of the southern part of La Rioja province were analysed during the period from 2014 to 2017. Six samplings were carried out to estimate the occupancy by T. infestans in patches assigned with different qualities. During the studied period, changes in the occupancy status of the patches among samplings were recorded, and the metapopulation variables which affect the occupancy of T. infestans were analysed. The results showed that all patches, even those considered of lower quality and smaller size, were occupied by T. infestans in a range from 3.8% to 25.5%. In general, the probability of T. infestans occupancy among samplings showed no difference among all studied patches. The occupancy of patches by T. infestans was associated with "department", "number of patches" and "number of positive patches in the radius of 400 m" (analysis GEE models). However, "patch quality", "size", and "distance" showed no effect on T. infestans occupancy. 44.1% of patches with BND were occupied at least once during the study period. Some of these showed "persistent occupancy" by T. infestans. No differences in the T. infestans occupancy between BNDs and TDs were observed. These results allowed us to analyse the impact of the new housing construction as a vector control measure in the metapopulation context of La Rioja province.