Prevalence of Dirofilaria immitis (Nematoda: Filarioidea) in mosquitoes from northeast Arkansas, the United States.

A mosquito survey was conducted to identify which species of mosquitoes carry Dirofilaria immitis (Leidy) (Nematoda: Filarioidea), dog heartworm, in northeast Arkansas. Using polymerase chain reaction, mosquitoes were analyzed for D. immitis, Dirofilaria repens Railliet & Henry, and Acanthocheilonema dracunculoides Cobbold. Mosquitoes were collected from April to October 2009 using black light ultraviolet traps baited with dry ice. Sixteen mosquito species were identified. D. immitis was identified in nine mosquito species, which included Aedes vexans (Meigen), Anopheles quadrimaculatus Say, Anopheles punctipennis (Say), Culex pipiens quinquefasciatus Say, Culex erraticus (Dyer & Knab), Culiseta inornata (Williston), Psorophora columbiae (Dyer & Knab), Psorophora ferox (Humboldt), and Psorophora howardii Coquillett. No D. repens or A. dracunculoides DNA was amplified. Of the 1,212 mosquito pools tested, 7.3% were positive for D. immitis. Frequency of D. immitis infections from six collection sites ranged from 2.1 to 19.4%. Ae. vexans and An. quadrimaculatus were the two most abundant species, composing 58.7 and 23.7% of the total mosquitoes collected, with 9.6 and 6.9% of pools positive for D. immitis, respectively. To investigate localized vector infection rates of D. immitis, mosquitoes were collected from inside the kennel of a heartworm-positive dog. Of the 114 mosquitoes collected, 84 (73.7%) were positive for D. immitis. The frequency of D. immitis-infected mosquitoes collected near a heartworm-positive dog was considerably higher than in the original six collection sites, suggesting a single heartworm-positive dog potentially increases infection pressure on susceptible animals sharing mosquito exposure.