Lessons Learned from Past Zoonotic Disease Outbreaks
Over the last century, we’ve experienced outbreaks that have had and are still having a considerable impact on both animal and human populations – called zoonotic diseases.
The good news is, we are becoming more adept at understanding how to contain and combat disease spread and it starts with animals.
Vaccinating animals when possible
Amidst an outbreak it’s often human vaccines that seem like the logical area of focus, to control it. Yet, animal vaccines can be as effective and, in the case of rabies, more effective at slowing the spread.
Dogs are the main carriers of the disease to humans in areas across the world including South Africa, South East Asia and the Americas. It’s been found that vaccinating dogs is often the best strategy to interrupt transmission to humans and a more cost-effective solution to expensive human rabies treatment. The Mission Rabies campaign is a great example, vaccinating more than 1.3 million dogs and significantly reducing the human death rate in their key project sites.
Meanwhile, animal health companies that produce vaccinations for pigs to help prevent swine flu, are using surveillance teams to monitor pathogens that may be problematic in future. These vaccines often require regular updates to keep pace with new types of the virus.
Understanding environmental and cultural factors
Rift Valley Fever has broken out in Kenya several times in recent years. Spread by mosquitoes, an outbreak can be linked to heavy persistent rains which provide the perfect environment for buried mosquito eggs to hatch. Meanwhile in many areas of the world, dog ownership and free-roaming dogs is part of the culture which can make control programs for rabies complex.
A combination of interventions, such as tracking environmental changes, for example the weather, and helping to educate local populations about the dangers of certain diseases alongside vaccination strategies are being used to slow and predict outbreaks.
Monitoring disease levels in wildlife
Scientists across the world are putting in place surveillance programs to spot and predict unusual activity in wildlife, often the starting place for pathogens. A study of 150 pathogens known to jump from animals to humans found that half caused visible symptoms in animals, making it possible to spot warning signs before it spills over into humans.
As human communities grow and encroach on wildlife populations, the risk of disease adaption and transmission becomes greater. Experts at University College London have created a model that could help decision-makers assess the impact of big policy changes on zoonotic transmission, for example changing grasslands into agricultural lands. Using information about the conditions from past Lassa fever outbreaks in West Africa, the team have been able to map the mechanics of the disease’s spread with environmental changes to predict how it might move.
Human doctors and veterinarians working together
Gradually, scientists from the worlds of animal, human and environmental health are working together to share knowledge so we can better understand infectious diseases and how they jump from animals to humans. Scientists at the Center for One Health Research at the University of Washington are using data and molecular technologies to tackle infectious diseases, while the One Health Poultry hub is dedicated to ensuring the safe growth of the poultry production sector as global demand for protein increases.
More than 60 per cent of emerging infectious diseases are zoonotic, so keeping animals in good health, is often our first line of defense in helping keep outbreaks under control.