Molecular Surveillance of Dirofilaria immitis in Field-Collected Aedes albopictus from Southeastern Virginia.

Dirofilaria immitis, also known as dog heartworm, is a filarial nematode of medical and veterinary importance. It is primarily transmitted by mosquitoes of the genera Aedes, Anopheles, Culex, and Mansonia, including the invasive Aedes albopictus. While primarily a veterinary pathogen, this parasite occasionally causes cutaneous or pulmonary dirofilariasis in humans. The aim of this study was to investigate the status of D. immitis in Ae. albopictus, a competent invasive vector, and to assess its prevalence in the mid-Atlantic United States. Aedes albopictus specimens were collected from various urban and suburban localities in Suffolk, Virginia, during 2023. Genomic DNA extracted from the mosquitoes was screened for D. immitis using diagnostic genes in PCR assays, and the resulting products were sequenced to confirm the presence of this parasite's DNA. Additionally, the host choice of Ae. albopictus was identified using PCR assays targeting the mitochondrial cytochrome b gene and sequencing. Dirofilaria immitis was detected in 9.2% (53/579) of the tested mosquito specimens, comprising 12.1% (46/379) of blood-fed and 3.5% (7/200) of non-blood-fed mosquitoes. Aedes albopictus predominantly obtained their blood meals from domestic cats and Virginia opossums. Among the D. immitis-positive specimens, the majority had obtained their blood meals from domestic cats and white-tailed deer. Our study provides evidence of the potential role of Ae. albopictus in the maintenance and transmission of D. immitis in this region and highlights the utility of xenosurveillance for tracking pathogen circulation in animal populations.