Key facts
- Sentinel chickens are used to detect early signs of West Nile virus and Eastern equine encephalitis.
- Delaware maintains flocks of four chickens at 20 locations across the state.
- The sentinel chicken program in Delaware began in the early 1980s.
- Scientists are using historical data from sentinel chickens to develop models predicting disease severity.
- Chickens are considered 'dead-end hosts' for these viruses, meaning they can test positive but cannot spread the diseases.
US scientists are employing sentinel chickens as an early warning system to track the spread of West Nile virus and other mosquito-borne illnesses. The Centers for Disease Control and Prevention (CDC) noted in July that West Nile virus transmission began unusually early in some states, with the most cases in early summer since 2004. In response, Delaware utilizes flocks of chickens at 20 locations throughout the state, a program that has been in place since the early 1980s.
These sentinel chickens, often referred to as the 'canary in the coal mine,' can often predict when virus activity is increasing, enabling officials to target mosquito control efforts and advise the public on necessary precautions. Veterinarians can also ensure horses are vaccinated, and doctors can be more vigilant for flu-like symptoms, especially outside of the typical flu season, to facilitate faster diagnoses. The chickens are considered 'dead-end hosts' as they can contract the viruses but cannot transmit them to other animals or humans, making them ideal for monitoring.
While some states have transitioned to testing mosquito pools, which can be faster, Delaware has opted to rely solely on chickens. Tom Moran, head of the mosquito control section at the Delaware department of natural resources and environmental control, explained that chickens sometimes detect virus activity in areas that mosquito pools miss. Furthermore, the fixed location of the chickens provides more precise information about where infected mosquitoes are active.
Researchers like Lindsay Campbell at the University of Florida are digitizing decades of data from sentinel chicken programs and combining it with environmental factors such as temperature and precipitation to develop predictive models for West Nile and Eastern equine encephalitis (EEE) seasons. This historical data helps scientists understand the conditions that contribute to more severe or milder years for these diseases. Robert Guralnick, a co-author with Campbell, noted that this data allows for the examination of virus ebbs and flows over time, which can then be linked to environmental characteristics to predict elevated activity.