July 28, 2021

MCHD places sentinel chickens throughout the county to monitor for diseases

MOBILE, Ala. — For almost 30 years, the Mobile County Health Department’s (MCHD) Vector Services has monitored sentinel chickens placed throughout the county to help detect the presence of viruses carried by mosquitoes. The practice is being renewed, as the first of 13 coops were deposited last Friday in various predetermined locations.

In April, 100 chicks arrived at Vector Services (a vector is any insect, rodent, or animal capable of harboring or transmitting diseases to humans) the day after being hatched. Vector Services keeps the chickens in a facility that is a half-enclosed hen house and half-screened yard. It has taken several months for the chickens to mature enough to be placed into service.

Prior to the coops being dispatched, the chickens received their initial blood draw to ensure they were healthy. They have also been vaccinated for fowl pox. Each hen is then numbered, and a band is placed on them for tracking purposes.

Starting soon, the Vector Services inspectors will draw blood samples at each location from the wings of two hens, usually on Mondays. The samples are sent to the Florida Department of Health Laboratory in Tampa. The results are available by that Friday.

The tests can reveal the presence of West Nile Virus (WNV), Eastern Equine Encephalitis and St. Louis Encephalitis. MCHD received a report this week of a human case of WNV. Because of patient privacy rights under the federal Health Insurance Portability and Accountability Act (HIPAA), no additional identifying information will be made available to the public. Residents need to be vigilant in preventing bites.

With the use of 13 coops, it means only 52 hens are used at one time. The rest are kept in reserve at Vector Services. If one dies, the remaining three are left in the field. Should two hens die, the entire coop is replaced.

The program continues into the fall, usually until Thanksgiving or mid-December. At that point, the hens are given away to the people at the locations where the coops are kept. A new group of 100 chicks will start the program the following spring.

Vector Services also has mosquito traps set up across Mobile County. The traps are used with reports from inspectors and complaints from the public to track the local mosquito population. There are more than 50 species of mosquitoes in Mobile County.

Since 2018, those collections from the traps are brought to researchers at the University of South Alabama on a weekly basis. An entomologist will identify and sort the mosquitoes into pools. A virologist will screen the pools for viruses including Dengue, Zika, and Chikungunya using high-throughput molecular methods.

Vector Services’ fleet of trucks has been covering 50 routes across Mobile County with night-time spraying since May. Vector Services is rotating first- and second-generation chemical insecticides and organophosphates so that no tolerance is built up in the mosquito population.

MCHD also has an airplane — a Cessna 182Q — that can spray insecticides along coastal areas and in other places that are inaccessible by truck.

“The Mobile County Health Department opened in 1816 to deal with Yellow Fever, which we learned later was being carried by mosquitoes,” said Dr. Bernard H. Eichold II, Health Officer for Mobile County. “We are still fighting mosquitoes today, and I am sure we are going to be for a long time.”

To report an issue with mosquitoes, call 251-690-8124 or email VectorServices@mchd.org. To learn more, please visit https://mchd.org/vector-control.