Serious rat-spread disease hits Waikato
30 September 2006

A debilitating disease spread by fleas from rats has arrived in the Waikato, prompting medical authorities to launch an investigation.

Eleven cases of rickettsia have been confirmed in the Waikato since May - none have been found in the rest of the country this year.Before this year there had been only 25 cases ever recorded in New Zealand. The closest the disease had come to the Waikato was the Coromandel Peninsula.

Rickettsia typhi, also known as murine typhus, causes severe fever, headache, muscle pain, dry coughs, nausea, vomiting, and often a rash. Without antibiotic treatment, intense fever can last for up to three weeks and lethargy for months.
"You can become very sick," said Waikato medical officer of health Anita Bell."All our cases have been hospitalised."

Rickettsia typhi can be fatal and is a close relative to typhus, which killed millions during the Napoleonic wars.

Waikato Hospital infectious diseases physician Graham Mills said New Zealand had not had a fatality from rickettsia yet, but a previous case in Auckland put the patient in intensive care.

Dr Bell said the disease was usually transmitted by fleas from rats, sometimes from bites. But she suspected the major cause was inhalation of flea faeces."You might go to the barn to get some wood and disrupt some flea faeces. It becomes airborne and you breathe it in," she said.

All 11 Waikato cases were in rural areas or on lifestyle blocks.Most cases had been in middle-aged or older people, and Dr Bell said young people tended not to show many symptoms. There were probably a lot of people in the Waikato who had the disease but did not yet know it.

Rickettsia had an incubation period of one to two weeks. A specific blood test was needed to identify it.Dr Mills said it was possible some people who thought they had the flu this winter actually had rickettsia.

The Public Health Unit and infectious diseases staff are investigating, trying to see if there is a single source for the disease. Dr Mills said letters were being sent to GPs to raise awareness.

"We're saying we now know we do have rickettsia. It's here now on farms and lifestyle blocks. How do we go about eradicating this disease now that we know it is on fleas that reside here?"

Dr Mills said rickettsia primarily occurred between April and September so Waikato people should not be exposed to it now. He suggested the cold winter might have seen rats living nearer to humans."They're coming inside more," he said. The escalation could also be due to the fact that recognition of the disease had increased, he said.

Rickettsia was first diagnosed in New Zealand in 1991 and in the past there was a tendency to look for it only in people who had travelled overseas.Fleas on rats are being blamed for the spread of rickettsia.

- The Waikato Times