Flea-carrying possums 'bring fever'

New Zealand's pest population of 70 million Australian possums may be doing more than killing off native forests and spreading bovine tuberculosis, health officials say.

The possums are thought to have become a reservoir of infection for a form of typhus fever known as murine typhus.

Murine typhus - which Auckland Healthcare says kills about 4 per cent of hospitalised patients - is caused by a bacteria, Rickettsia typhi, and is spread by fleas.

Auckland public health officials say that blood tests have identified five cases in the Kaukapakapa and Kaipara region, north of Auckland, and two from Clevedon and Karaka in south Auckland.

"A feature of all cases was their exposure to possums.

"It is possible that possums act as reservoir hosts," they said in a newsletter, Public Health Advice.

Auckland officials yesterday said New Zealand's first case had been diagnosed almost by accident.

A laboratory technician who had a test kit for the illness tested a blood sample from a patient whose illness had proved difficult to diagnose.

Overseas, murine typhus is usually found in rats.

It is spread by the oriental rat flea to humans who rub or scratch infected flea faeces into flea bites.

Murine typhus is different to the more serious epidemic typhus, which has caused the deaths of millions, but is transmitted by lice.

In the United States, where between 30 and 50 cases of murine typhus are reported each year, about 75 per cent of the infections are thought to be from cat fleas.

In foothill and orchard areas around eastern Los Angeles, most infections are thought to come from American opossums that are heavily infested with fleas.

In New Zealand, the main features of murine typhus are headache, fever and muscle pain, with rashes appearing in about half of the cases.

Untreated, the illness usually lasts two or three weeks and a blood test may be the only way to diagnose it.

- NZPA