Effects of ultra-low volume applications of malathion in Hale County, Texas. IV. Arbovirus studies.

Abstract

Vector mosquito populations, arbovirus infection rates among mosquitoes and avian hosts, sentinel chicken flock transmission indices, and human clinical and inapparent arbovirus infection rates were monitored to evaluate the effectiveness of ultra-low volume (ULV) applications of malathion for control of arthropod-borne encephalitis in Hale County, Texas, during 1967. Effective control of arbovirus activity was not obtained by weekly treatments of towns with areas of approximately 17 and 65 km2 (6.5 and 25 square miles). Barrier treatments between the towns and the areas of Culex tarsalis breeding may have reduced infiltration of infected vector mosquitoes into the treated towns. Retreatment at 3-day intervals also may have resulted in sustained vector control and reduced arbovirus activity.