Livestock vaccination campaigns are often favorites of the humanitarian aid community because they engage a lot of local people, can spend large sums of money relatively quickly, and popular sentiment is that “you can’t go wrong with vaccinations, right?”
The answer, as with most things, is that you CAN go wrong with vaccinations if the specific circumstances are not carefully considered.
Mass vaccination of livestock is a potent tool in controlling and preventing diseases, safeguarding what in many societies comprises the most important single family resource. On the other hand, poorly thought-out campaigns may provide little benefit for animal owners. At worst, they can render animals even more vulnerable to disease.
Space-fill drawing of a whole Zika virus particle, and a cross-section as it interacts with a cell. The outer capsid is pink, the membrane purple, and RNA genome in yellow. Cell-surface receptors are green, cytoskeleton blue, and blood plasma gold. David Goodsell
Zika virus is one of a large number of viruses transmitted between animals (including humans) by arthropod insects. These are called arthropod-borne viruses, or arboviruses for short. The arthropod vectors in the case of Zika virus are certain mosquito species that transmit the virus from one host to another. But arboviruses also require a reservoir host: one or more species of animal within whose population the virus is maintained for long periods in relative stability. In other words, the virus circulates at low levels in the population, avoiding the infection of so many individuals that the general population becomes immune to it and the virus has nowhere to go but extinct.
Researchers are getting a pretty good handle on the various mosquito vectors of Zika virus. But we know very little about what animal species act or may act as reservoir hosts for the virus. This information is crucial for understanding the virus’s transmission dynamics and geographical distribution. Without understanding Zika’s reservoir(s) or other hosts, control and prevention will be difficult and inefficient at best, counterproductive at worst.
Sheep and Ankole cattle, Uganda Charles Hoots
As the world embarks on a quest to eradicate a second animal disease, peste des petits ruminants, lessons from the last successful eradication campaign will be invaluable. The stakes are high as the disease kills millions of sheep and goats, costing the world billions of dollars each year – and eradication campaigns are expensive. This post and the next look at several characteristics of this disease that make it a good candidate for such an effort.