— By Abigail Martin
Rabies is a global health issue, claiming fifty to sixty thousand lives every year. Most of these deaths occur in sub-Saharan Africa and South Asia. The rabies virus is usually transmitted to humans through the bite of an infected dog. Because children are the most susceptible to attacks by rabid dogs, they account for the vast majority of deaths.
Veterinarian Guy Palmer is conducting research in Tanzania on a sustainable rabies vaccination program.
Palmer explained, “If we can get around 60% we can actually control a disease outbreak. We don’t need to vaccinate every dog. We need to vaccinate somewhere around 60%. So, the question becomes, can you actually achieve that level of vaccination in a low resource setting?”
Palmer has a PhD in infectious diseases and is an adviser to the Global Development Program at the Bill and Melinda Gates Foundation.
He and his colleagues work with community leaders to arrange dog vaccination clinics. Word spreads quickly and people gather with their animals. But Dr. Palmer was surprised when he saw the dog owners.
“Children own these dogs,” he said. “They bring with them their vaccination cards and it’s amazing the percentage that we have that have the vaccination card from a previous trip. We come every year to each village. In general, these families don’t have a lot of papers and certificates. They tend to put a value on those they have.”
While the vaccination effort has been successful, Palmer says there’s more to do to make it sustainable over the long-term.
“We now have about 15 years of experience with this. And if you continue these vaccination campaigns, you completely suppress rabies. The challenge is how do you get away from this model we have now, which is donor driven. It costs us about three dollars to vaccinate a dog in those regions and that’s not something that’s, at the moment, sustainable by either the individuals nor by the government. Using country-wide approaches, it’s possible to actually move rabies out of a region and then vaccinate only around the periphery to control the disease. To do that what we’ve really got to do is reduce costs,” he said.
About one dollar of the vaccine cost is keeping it cold. Fortunately, silk polymers have the potential to revolutionize the storage of vaccines. Strands of silk proteins are purified from silkworm cocoons and are incorporated into the vaccine serum. The silk polymers don’t affect the vaccine’s effectiveness, but they stabilize the serum so that it doesn’t degrade under high temperatures. These polymers can protect vaccines at up to 45 degrees Celsius for more than six months. The vaccines remain more than eighty percent potent despite storage at these temperatures.
Dr. Palmer says there’s another way to reduce costs, as well.
“Working with the communities to get them to vaccinate is one of the major goals we have because that will reduce one of our other major costs, which is transport. If we can actually get the vaccines there, then they can maintain them locally and do the local vaccinations,” he said.
Dr. Palmer’s rabies vaccination studies may present other healthcare opportunities. The vaccination clinics could also be used to provide care and treatment for children when they bring their dogs to be vaccinated.