How a Vaccine for Chickens Can Help Save the Lemurs
Oct 27, 2019
National Geographic Explorer Dr. Christopher Golden and his team of Harvard Planetary Health Scholars spent six weeks in Madagascar to better understand the human health impacts of environmental change. This series of stories will document this journey across Madagascar through the personal experiences of these students.
By Akshaya Annapragada, Harvard University undergraduate and Planetary Health Undergraduate Scholar
Recently, we traveled to the remote village of Antaravato situated on the eastern border of the Makira Forest in northeastern Madagascar. After a three-hour car ride over dirt roads, and a five-hour hike through knee-deep mud, we reached the village and were warmly welcomed to the home of Maman’i AimeÌ and Papan’i AimeÌ (two of Chris’s research assistants and friends), where we would stay for the next week.
One of the many challenges faced by the Antaravato community is food security. Since time immemorial, they have hunted and eaten terrestrial wildlife for food, including birds, tenrecs, bats, carnivores and lemurs. While this meat is rich in nutrients and has historically been plentiful, wildlife stocks have steadily declined in response to overhunting and environmental changes. This scarcity is in part responsible for the severe malnutrition found throughout Antaravato, where approximately 35 percent of all children exhibit growth stunting. In contrast to its nutritional value, contact with wildlife presents a risk for infectious disease transmission, making it a risky source of food. To protect the health of both the Antaravato community and their surrounding wildlife populations, the MAHERY (Madagascar Health and Environmental Research) team is piloting nutritional interventions that provide sustainable poultry sources as an alternative to wildlife hunting.
In the past, chicken has not served as a consistent and economical food source because village poultry flocks are vulnerable to Newcastle disease, a virus that causes respiratory and nervous system failure in chickens. Community members were faced with inconsistent numbers in their chicken flocks given the high likelihood that chickens would die of disease before they could lay eggs, be sold for money, or butchered for meat. In order to combat these factors, MAHERY is piloting a Newcastle disease vaccination program in conjunction with the Wildlife Health Network (led by Drs. Graham Crawford and Susan Ostapak), Harvard T.H. Chan School of Public Health, IMVAVET (Madagascar’s National Institute for Veterinarians and Vaccinations), and the Wildlife Conservation Society to protect vulnerable chicken populations in a small set of communities in the Makira and Masoala forests.
During our time in Antaravato, we participated in the fourth round of vaccinations of this program and had the opportunity to observe the vets and para-vets (trained non- specialists who assist the vets) implementing this intervention. The vaccination is administered three times per year to each chicken. For convenience, the vaccine is delivered via eye drop, rather than traditional needles. The innovations in producing a thermostable live vaccine via eye dropper are several.
First, it can withstand the temperature vagaries in Madagascar, where electricity and refrigeration are often impossible.
Second, it provides herd immunity because it is a live vaccine, hence improving coverage as compared to past versions of the vaccine.
Finally, it can be delivered by trained non-specialists since it does not require a venous injection. IMVAVET was able to successfully produce this innovative vaccine through the efforts and support of the San Francisco Zoo, Harvard T.H. Chan School of Public Health, University of Sydney, and the Kyeema Foundation.
Vaccinating all the chickens in the village is a challenging task, requiring the vets and para-vets to travel door-to-door to reach every household, no matter how remote. Once at a home, the vets and village residents must work together to round up every single chicken, and vaccinate them. Existing evidence suggests that 85 percent vaccination coverage will be sufficient to ensure herd immunity; however, the prevalence of vaccination is still well below this rate due to the cost of the vaccine and the village residents’ desire to know with certainty that the vaccine works before adhering to a repeated vaccination schedule. While the herd immunity target has not been reached yet, the early success and popularity of this intervention gives us hope that it will be achieved in the future.
Chicken is a particularly promising sustainable food source in Malagasy communities for several reasons.
First, Chris’ past empirical research found that for the local Malagasy people, who are predominantly of the Betsimisaraka and Tsimihety ethnolinguistic groups, chicken is a top taste preference when compared to other domesticated meats and 26 types of bushmeat. This suggests that if chickens can be raised in an efficient and cost-effective manner, households will benefit in a variety of ways, including increased chicken and egg consumption, and earned income from chicken sales.
Second, chickens are an acceptable food source for all sub-populations within local Malagasy culture (i.e., across religions, socio-economic status, gender lines, and age classes). While many Malagasy households maintain fady, or taboos, against the consumption of certain meats, there are none against chicken consumption.
Third, the economics of this intervention are favorable. Currently, chicken is more expensive than wildlife because it cannot be raised productively. By increasing chicken survival, the vaccine intervention will drastically increase productivity, hence lowering chicken prices, and making them an attractive purchase option. For this reason, MAHERY’s intervention has great potential to improve the economic favorability of chicken.
Fourth, in Malagasy culture, chicken is often seen as a gendered female asset. By empowering women, this intervention will help the entire household, and can serve to protect especially vulnerable women and children.
Finally, of all the potential livestock to raise in villages adjacent to rain forest, chickens have the least likelihood to be environmentally damaging. We do not anticipate massive increases in the stock population of chickens in the village; however, we do envision increased productivity and stability of stocks leading to increased consumption of chicken and eggs. We also envision increased chicken sales to peri- urban or urban areas, generating new income that can be channeled to support food security and other social protections.
Through vaccinating the chickens in Antaravato, we hope to provide food security for the community, and protect declining bushmeat populations. Currently the vaccine is inexpensive, costing only $0.03 USD per chicken per dose (just shy of $0.10 per year), to protect a source of meat that can feed an entire family. Our remaining tasks are mainly around education and motivation to improve vaccine coverage within the villages where we work.
Chickens roost on the roof tops of homes in the village of Maharihy.
A debt of gratitude is owed to the Rasmussen Family Foundation, the Norvig Family Foundation, and the St. Louis Zoo’s WildCare Institute for providing financial support for the execution of the project.