Optimization of Control Strategies for Non-Domiciliated Triatoma dimidiata, Chagas Disease Vector in the Yucatán Peninsula, Mexico

Abstract

BackgroundChagas disease is the most important vector-borne disease in Latin America. Regional initiatives based on residual insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is now a key challenge for disease control.Methodology/Principal FindingsA mathematical model was developed to predict the temporal variations in abundance of non-domiciliated vectors inside houses. Demographic parameters were estimated by fitting the model to two years of field data from the Yucatan peninsula, Mexico. The predictive value of the model was tested on an independent data set before simulations examined the efficacy of control strategies based on residual insecticide spraying, insect screens, and bednets. The model accurately fitted and predicted field data in the absence and presence of insecticide spraying. Pyrethroid spraying was found effective when 50 mg/m2 were applied yearly within a two-month period matching the immigration season. The >80% reduction in bug abundance was not improved by larger doses or more frequent interventions, and it decreased drastically for different timing and lower frequencies of intervention. Alternatively, the use of insect screens consistently reduced bug abundance proportionally to the reduction of the vector immigration rate.Conclusion/SignificanceControl of non-domiciliated vectors can hardly be achieved by insecticide spraying, because it would require yearly application and an accurate understanding of the temporal pattern of immigration. Insect screens appear to offer an effective and sustainable alternative, which may be part of multi-disease interventions for the integrated control of neglected vector-borne diseases.

Triatomine Infestation in Guatemala: Spatial Assessment after Two Rounds of Vector Control

“…This result confirmed previous findings indicating that a maximum reduction in triatomine abundance is achieved when insecticide spray is administered in early April, just as the transient seasonal infestation with T. dimidata begins on the Yucatan peninsula. 30,31 In these previous studies, the effectiveness of spray decreased slightly if administered in May or June and dropped to a much lower level during the remaining month of the year. Although this effect of season of spray administration was present in the first spray, season did not impact reinfestation after second spray.…”

House Infestation Dynamics and Feeding Sources of Triatoma dimidiata in Central Veracruz, Mexico

“…Indeed, it is now well established that the efficacy of conventional insecticide spraying is short-lived in the case of non-domiciliated triatomines seasonally infesting houses. [28][29][30][31] Previous control efforts in Veracruz indicated that three insecticide applications 8 months apart were required to reduce T. dimidiata infestation, 32 but there was no follow-up to assess potential re-infestation after interrupting control interventions. Re-infestation by T. dimidiata following insecticide spraying has been frequently observed in the Yucatan peninsula, Mexico, 28,31 as well as in Guatemala.…”

Genetics and evolution of triatomines: from phylogeny to vector control

“…Similarly, the competitive advantage of T. infestans could result from its ability to ingest larger blood meals, while having a lower requirement to complete its (shorter) life cycle (Pereira et al, 2006). Clearly, interactions between (domestic) T. infestans and (peri-domestic and sylvatic) other triatomine species also involve a dispersal-competitive trade-off (Oscherov et al, 2004), and could thus be better understood if studied in a meta-population dynamic framework such as the ones available for triatomines (Gourbière et al, 2008;Barbu et al, 2009Barbu et al, , 2010Barbu et al, , 2011Slimi et al, 2009, and references therein). Understanding the balance between competitive and dispersal abilities will allow understanding the impact of competition between triatomines on parasite transmission, as suggested by theoretical studies (Gourbière and Gourbière, 2002;Begon, 2008).…”

“…When triatomine populations are present in domestic, peri-domestic and sylvatic ecotopes, and gene flow among ecotopes is significant, insecticide spraying is of limited efficacy (Dumonteil et al, 2004;Barbu et al, 2009), likely because populations can be rapidly rebuilt by migrants. Thus, the control of such non-domiciliated or autochthonous triatomines remains a major problem for vector control , and novel approaches such as screens, bednets and house improvements will be necessary to interrupt transmission (Figure 4) (Monroy et al, 1998(Monroy et al, , 2009Barbu et al, 2009Barbu et al, , 2011Ferral et al, 2010).…”

“…Thus, the control of such non-domiciliated or autochthonous triatomines remains a major problem for vector control , and novel approaches such as screens, bednets and house improvements will be necessary to interrupt transmission (Figure 4) (Monroy et al, 1998(Monroy et al, , 2009Barbu et al, 2009Barbu et al, , 2011Ferral et al, 2010).…”