title: Occurrence of avian Plasmodium and West Nile virus in Culex species in Wisconsin.
abstract: The occurrence of multiple pathogens in mosquitoes and birds could affect the dynamics of disease transmission. We collected adult Culex pipiens and Cx. restuans (Cx. pipiens/restuans hereafter) from sites in Wisconsin and tested them for West Nile virus (WNV) and for avian malaria (Plasmodium). Gravid Cx. pipiens/restuans were tested for WNV using a commercial immunoassay, the RAMP WNV test, and positive results were verified by reverse transcriptase-polymerase chain reaction. There were 2 WNV-positive pools of Cx. pipiens/restuans in 2006 and 1 in 2007. Using a bias-corrected maximum likelihood estimation, the WNV infection rate for Cx. pipiens/restuans was 5.48/1,000 mosquitoes in 2006 and 1.08/1,000 mosquitoes in 2007. Gravid Cx. pipiens or Cx. restuans were tested individually for avian Plasmodium by a restriction enzyme-based assay. Twelve mosquitoes were positive for avian Plasmodium (10.0%), 2 were positive for Haemoproteus, and 3 were positive for Leucocytozoon. There were 4 mixed infections, with mosquitoes positive for > 1 of the hemosporidian parasites. This work documents a high rate of hemosporidian infection in Culex spp. and illustrates the potential for co-infections with other arboviruses in bird-feeding mosquitoes and their avian hosts. In addition, hemosporidian infection rates may be a useful tool for investigating the ecological dynamics of Culex/avian interactions.
authors.affiliation: Department of Entomology, University of Wisconsin Madison, 237 Russell Labs, 1630 Linden Drive, Madison, WI 53706, USA.
authors.forename: Tony
authors.initials: T
authors.lastname: Hughes
authors.forename: Patrick
authors.initials: P
authors.lastname: Irwin
authors.forename: Erik
authors.initials: E
authors.lastname: Hofmeister
authors.forename: Susan M
authors.initials: SM
authors.lastname: Paskewitz
mesh_terms: D000818:Animals; D001717:Birds; D003465:Culex / Q000469:parasitology* / Q000821:virology*; D007303:Insect Vectors / Q000469:parasitology / Q000821:virology; D008289:Malaria, Avian / Q000635:transmission*; D010961:Plasmodium / Q000302:isolation & purification*; D014902:West Nile virus / Q000302:isolation & purification*; D014922:Wisconsin