Effectiveness of Large-Scale Chagas Disease Vector Control Program in Nicaragua by Residual Insecticide Spraying Against Triatoma dimidiata

Abstract

Abstract. Chagas disease is one of the most serious health problems in Latin America. Because the disease is transmitted mainly by triatomine vectors, a three-phase vector control strategy was used to reduce its vector-borne transmission. In Nicaragua, we implemented an indoor insecticide spraying program in five northern departments to reduce house infestation by Triatoma dimidiata. The spraying program was performed in two rounds. After each round, we conducted entomological evaluation to compare the vector infestation level before and after spraying. A total of 66,200 and 44,683 houses were sprayed in the first and second spraying rounds, respectively. The entomological evaluation showed that the proportion of houses infested by T. dimidiata was reduced from 17.0% to 3.0% after the first spraying, which was statistically significant (P < 0.0001). However, the second spraying round did not demonstrate clear effectiveness. Space-time analysis revealed that reinfestation of T. dimidiata is more likely to occur in clusters where the pre-spray infestation level is high. Here we discuss how large-scale insecticide spraying is neither effective nor affordable when T. dimidiata is widely distributed at low infestation levels. Further challenges involve research on T. dimidiata reinfestation, diversification of vector control strategies, and implementation of sustainable vector surveillance.

Uncovering vector, parasite, blood meal and microbiome patterns from mixed-DNA specimens of the Chagas disease vector Triatoma dimidiata

“…In its place, endemic triatomines including T . dimidiata have colonized vacant peridomestic and domestic habitat niches and have slowly changed the dynamics of disease transmission in these ecotopes [ 24 , 25 , 26 , 27 , 28 ]. Triatoma dimidiata is widely distributed from Mexico to Perú in sylvatic, peridomestic and domestic habitats [ 26 , 29 , 30 ].…”

The resilience of Triatoma dimidiata: An analysis of reinfestation in the Nicaraguan Chagas disease vector control program (2010–2016)

“…During the following attack phase, 69 houses were excluded from the large-scale spraying because they belonged to urban blocks where the risk of T . dimidiata house infestation was considered specially low [ 28 ]. Since our purpose is to assess the pattern of T .…”

Integrated vector control of Chagas disease in Guatemala: a case of social innovation in health

“…Triatoma dimidiata is a native species (originated in the region) [10] and endemic vector that is in the process of domiciliation (adapting to and colonization of human environments), while also living and propagating in sylvatic (forest) conditions [11]. From 2000 to 2008, the Government of Guatemala pursued a massive insecticide campaign, but the species still invades and colonizes houses, presenting infestation indexes between 3 and 35% of houses [12,13]. Where T. dimidiata is not strictly domesticated, insecticide spraying has been ineffective [12] or needs to be repeated frequently due to reinvasion of insects from the sylvatic cycle in nearby forests [13].…”

“…From 2000 to 2008, the Government of Guatemala pursued a massive insecticide campaign, but the species still invades and colonizes houses, presenting infestation indexes between 3 and 35% of houses [12,13]. Where T. dimidiata is not strictly domesticated, insecticide spraying has been ineffective [12] or needs to be repeated frequently due to reinvasion of insects from the sylvatic cycle in nearby forests [13]. However, repeat applications are beyond the resources of many affected countries, and insecticides can cause environmental damage.…”