Feline HIV rampant in cats

By SIMON COLLINS

Up to a quarter of New Zealand's domestic cats and half of our wild cats may be infected with the feline equivalent of the HIV virus.

Auckland University masters student Jess Hayward has found the feline immunodeficiency virus (FIV) in 24 per cent of blood samples taken from domestic cats.

For wild cats, infection rates reached 40 per cent in Hawkes Bay and 55 per cent on Great Barrier Island.

However, her samples may be biased, as they come from cats either taken to vets or shot in the wild by the Conservation Department.

Healthy cats are less likely to be taken to vets except for spaying.

Most cats with the virus show no symptoms except for a short phase of two to nine weeks when the virus first strikes and again in the final phase of the virus, when it is usually fatal.

The symptoms are fever and diseased lymph glands. In the final, Aids-like stage, the cats lose weight and are liable to catch infections of the skin, mouth, eyes, respiratory and urinary tracts.

But in between the initial phase and the last stage, most cats with FIV have an "extra life" of between a few months and a few years when they do not show any disease symptoms.

Ms Hayward's study is one of the first to be based on searching for the genetic signs of FIV directly.

Most overseas studies have searched for antibodies produced by cats against FIV. These studies, now believed to understate the extent of FIV infection, have shown infection rates from 1 to 14 per cent in the US and 12 to 44 per cent in Japan.

Biology lecturer Dr Howard Ross has used the preliminary data from Ms Hayward's study to trace the genetic sequence of an original FIV "ancestor".

Auckland University and the University of Washington in Seattle are now seeking funding of about US$100,000 ($167,000) to recreate that ancestor virus as a vaccine.

Auckland University Professor Allen Rodrigo said similar viruses had attacked immune systems in most mammals for millions of years.

In monkeys and in most other cases, the host animals had adjusted to the viruses and no longer suffered any symptoms of disease. Individuals that did not adjust had died out.

The fact that FIV and HIV are still virulent sources of disease in cats and humans indicates that the viruses crossed into our two species relatively recently.