Improved vector control of Triatoma infestans limited by emerging pyrethroid resistance across an urban-to-rural gradient in the Argentine Chaco

Table 2 Distribution of house infestation with T. infestans by timed-manual searches according to type of environment and survey, Avia Terai, Chaco, 2011–2019

Years post-spraying (Date)	Environment	% of inspected houses (no. registered)	% of infested houses (no. inspected)^c	% of sprayed houses (no. sprayed)^d
(2011–2013)^b	Urban	13.3 (1409)^a	11.8 (187)	6.7 (94)^a
	Peri-urban	73.9 (307)^a	20.7 (227)	67.8 (208)^a
	Rural	61.7 (308)^a	40.0 (190)	61.4 (189)^a
0 (2015–2016)	Urban	29.2 (1409)	11.4 (412)^e	7.4 (104)
	Peri-urban	68.4 (307)	27.1 (210)^e	34.9 (107)
	Rural	89.6 (308)	42.4 (276)^e	87.3 (269)
1 (2016–2017)	Urban	63.9 (1455)	2.2 (930)	21.4 (311)
	Peri-urban	85.8 (323)	17.0 (277)	42.4 (137)
	Rural	87.7 (310)	21.7 (272)	20.3 (63)
2 (2017–2018)	Peri-urban	86.7 (338)	6.1 (293)	16.3 (55)
2 (2017–2018)	Rural	17.0 (305)	26.9 (52)	4.9 (15)
4 (2018–2019)	Rural	86.9 (283)	19.5 (246)	2.1 (6)

Baseline: October 2015–March 2016; 2011–2013 (first period)
^aComputed relative to the number of inhabited houses registered in 2015–2016
^bAdditional insecticide treatments during the surveillance phase included 122 rural houses sprayed in 2012–2013, 6 peri-urban houses in 2014–2015, and 87 urban houses in 2014–2015 (total, 215 houses)
^cHouse infestation prevalence was calculated as the sum of infested houses at survey t and those found infested between t − 1 and t relative to the number of houses inspected for triatomines
^dThe percentage of sprayed houses was calculated relative to the number of inhabited houses registered in each survey
^eObserved infestation prevalence

ISSN: 1756-3305