SREL Reprint #3613

Drug resistance in filarial parasites does not affect mosquito vectorial capacity

Erik Neff1, Christopher C. Evans2, Pablo D. Jimenez Castro2,3, Ray M. Kaplan2, and Guha Dharmarajan1

1Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA
2Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia,
Athens, GA 30602, USA
3Grupo de Parasitología Veterinaria, Universidad Nacional de Colombia, Bogotá 11001000, Colombia

Abstract: Parasite drug resistance presents a major obstacle to controlling and eliminating vector-borne diseases affecting humans and animals. While vector-borne disease dynamics are affected by factors related to parasite, vertebrate host and vector, research on drug resistance in filarial parasites has primarily focused on the parasite and vertebrate host, rather than the mosquito. However, we expect that the physiological costs associated with drug resistance would reduce the fitness of drug-resistant vs. drug-susceptible parasites in the mosquito wherein parasites are not exposed to drugs. Here we test this hypothesis using four isolates of the dog heartworm (Dirofilaria immitis)—two drug susceptible and two drug resistant—and two vectors—the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Ae. albopictus)—as our model system. Our data indicated that while vector species had a significant effect on vectorial capacity, there was no significant difference in the vectorial capacity of mosquitoes infected with drug-resistant vs. drug-susceptible parasites. Consequently, contrary to expectations, our data indicate that drug resistance in D. immitis does not appear to reduce the transmission efficiency of these parasites, and thus the spread of drug-resistant parasites in the vertebrate population is unlikely to be mitigated by reduced fitness in the mosquito vector.

Keywords: Aedes spp.; arthropod; disease transmission; Dirofilaria immitis; drug resistance; extrinsic
incubation period; filaria; macrocyclic lactones; mosquito; vector competence

SREL Reprint #3613

Neff, E., C. C. Evans, P. D. Jimenez Castro, R. M. Kaplan, and G. Dharmarajan. 2021. Drug resistance in filarial parasites does not affect mosquito vectorial capacity. Pathogens 10(1): 2.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).