The chickens that stand guard
By Jasmine McBain-Miller, Class of 2016
(Chicken image credit Stephen Mierendorrf via Unsplash)
They are our avian defenders. Our silent watchers of disease spread. They warn us of imminent dangers. They are our sentinel chickens.
While she may not look like a defender with her stumpy legs, tiny beak, and lack of scale armour, she is proving herself more than worthy of the title. Valiant chooks have been playing a vital role in tracking disease spread across Australia and abroad.
When it comes to monitoring the spread of mosquito-borne viruses, it can be quite challenging. You could track the number of people presenting to medical facilities with symptoms of the disease. But often people are misdiagnosed, information about the patients isn’t passed on to relevant authorities, and many infected people simply aren’t feeling ill enough to visit a doctor. All these factors limit the accuracy of disease tracking. And by the time people are seeking medical help, the disease has already spread to the human population. What if you wanted to be alerted to the disease before it started affecting people?
Fortunately there’s a solution: sentinel chickens!
If there’s a mosquito-borne disease which can infect chickens that you wish to monitor, just spread flocks of chooks in your area of interest. Hopefully any mosquitoes around will be attracted to the fleshy combs and wattles on the chickens’ heads and come to feed. As a mosquito feasts, it infects the chicken with the virus it was carrying. The chicken’s immune system recognises the viral threat and starts mass-producing antibodies against the virus.
Now, every so often take samples of your flocks’ blood and test it for antibodies. If the chickens’ blood have antibodies for the virus, you can be sure the virus has spread to the area. If none of the chickens in the area have the antibodies, it’s likely the disease has not reached there. That’s great news for the populace, but not so great for the virus.
In Australia we’ve used sentinel chickens across the country to track a number of viral infections, including Murray Valley Encephalitis and Kunjin virus. In the U.S. sentinel chickens have frequently been used for West Nile virus monitoring. In both scenarios, the sentinel chickens can give authorities an early warning of imminent disease outbreaks, allowing them more time to prepare and warn the community. With this knowledge the government might choose to spray the mosquito populations in the area with pesticide, which will hopefully prevent the outbreak from even occurring.
Any chicken that tests positive for the antibodies is no longer fit for guard duty; every time her blood is tested, it’ll continue to come back positive regardless of whether the virus is still present in the area. But the brave chook doesn’t worry about her honourable discharge from the line of duty. She was growing tired of the front-lines anyway. The viral infection didn’t affect her and she can trust she’ll be well looked-after. After all, she has a good chance of being rehomed. Here, she’ll be able to enjoy her retirement with endless bug hunting and dust bathing; every chicken’s dream! She’s earned it.
– Sentinel chicken farmers (News article)
– Sentinel Chickens: What birds tell us about our health and the world (Book by Peter Doherty)
– Example of sentinel chicken use in Australia (Study)