MOBILE, Alabama — For the second time in a week, a sentinel chicken used by the Mobile County Health Department to track mosquito-borne illness has tested positive for West Nile virus, this time in the Mount Vernon community.
How the county tracks the virus
The health department maintains flocks of chickens at various points around the county specifically to monitor for mosquito-borne diseases. Because the birds are regularly bitten by local mosquitoes but do not get sick from West Nile virus themselves, testing their blood gives health officials an early warning system for how widely the virus is circulating in the mosquito population before human cases appear.
Mobile County’s health officer said the latest positive result, confirmed through laboratory testing, means residents throughout the county should assume infected mosquitoes are present, not just in the Mount Vernon area where this particular bird was located.
Risk peaks through the fall
Health officials said the risk of mosquito-borne encephalitis in the Mobile area is highest from August through the first hard freeze of the fall, meaning residents could face elevated risk for at least another month or two depending on the weather. Mosquito activity tends to peak at dawn and dusk, so people spending time outdoors during those hours were urged to take extra precautions.
Recommended steps include wearing insect repellent any time someone is outside, especially during peak mosquito hours, and taking basic steps around the home such as eliminating standing water where mosquitoes breed. West Nile virus spreads in a cycle between birds and mosquitoes, with mosquitoes picking up the virus by feeding on infected birds and then transmitting it to other animals, including humans and horses, through subsequent bites.
No vaccine available for humans
While both humans and horses can become seriously ill from West Nile virus, health officials noted that the disease cannot spread directly from an infected person or horse to another person, since transmission requires a mosquito as the carrier. There is currently no vaccine available for humans, making prevention of mosquito bites the primary defense against the virus.
The Mobile County Health Department said it will continue regular testing of mosquitoes and sentinel chickens throughout the county as the risk season continues, and will notify the public of any additional positive results.