FARMERS across northern Europe are frantically vaccinating cattle and sheep against bluetongue this week, before the biting flies that carry the virus launch this year鈥檚 outbreak. Zookeepers are vaccinating their animals too, with some unlikely help: big, Mexican bloodsucking bugs.
All ruminants are susceptible to bluetongue, and it can kill them. The African BTV8 strain, which suddenly appeared in 2006 in Belgium and spread across most of north-west Europe last year, is especially virulent. A yak in a Belgian zoo died during last summer鈥檚 outbreak.
This year, a BTV8 vaccine is available, but it was designed for sheep and cattle. 鈥淲e don鈥檛 know what dosage will cause immunity in a camel,鈥� says Tim Bouts, chief vet for the London and Whipsnade zoos in the UK. Worse, the vaccine was tested using an injection under the skin. Semi-wild animals roaming free in large enclosures must be vaccinated by a dart to a muscle, which can affect dosage.
Advertisement
A blood sample taken weeks after vaccination will reveal whether the animal is immune, but in some species using a needle requires the animal to be sedated. This can be dangerous, particularly in species such as giraffes, as they are hypersensitive to anaesthetic.
Enter the Mexican kissing bug, a centimetre-long monster which can painlessly suck 3 millilitres or more of blood from an animal. A dozen European zoos have started taking blood samples using bugs bred at Wuppertal Zoo in Germany, which pioneered the technique. Bouts now plans to use them to monitor the effect of the bluetongue vaccine.
For calmer beasts, such as elephants, a jar containing several bugs is pressed to the skin. For less-approachable animals, bugs are released on the animal, then retrieved when they drop off, full of blood. This can be delicate, says Bouts. 鈥淥nce a hippo stepped on a full bug so we had to start over.鈥�
