El Nino Side Effect: Ticks That Might Carry a Nasty Bug

As if El Nino wasn’t causing enough headaches with gully-washer storms and house-toppling mudslides, it’s also responsible for a bumper crop of ticks in California.

Worse still, some of the nasty little parasites are carrying a disease called ehrlichia--a bacteria that causes a severe flu-like illness in humans.

Ehrlichia, an East Coast phenomena for about a decade, turned up in California two years ago in ticks plucked off blades of grass in Orange, El Dorado, Sonoma and Santa Cruz counties, said Dr. Jim Webb of the Orange County Vector Control District.

The culprit: ioxdid pacificus, the western black-legged tick that also is known to carry Lyme disease, Rocky Mountain spotted fever and babesiosis.

While the discovery of ehrlichia in California hardly qualifies as a public health emergency, the early discovery means Webb and his fellow researchers may be able to help doctors quickly diagnose and treat the illness when it turns up in humans.

“We like to be in a proactive public health mode,” Webb said. “The presence of this phenomena is not very high. The odds you are going to be infected with it here in Orange County are slim.”

A study published in the Journal of Clinical Microbiology last summer found two people--both in Santa Cruz County--who had been infected with human granulocyctic ehrlichia. Researchers found several infected ticks in that home.

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In Orange County, only one of 98 ticks tested positive for the bacteria. It was captured off a riding path in San Juan Capistrano in 1996. Since then, Webb’s researchers have found several small animals infected with ehrlichia, including the deer mouse.

“These microbes seem to be tying in with the deer mouse, the same reservoir host for the hantavirus. It’s a very important storehouse of these microbes, these germs, in nature,” Webb said. “There’s an interesting ecological relationship here.”

Finding the disease in humans proves more difficult.

“Doctors don’t even think of it. The typical symptoms are flu--headache and fever,” said Janet Foley, a UC Davis veterinarian tracking the spread of the bacteria on the West Coast. “Ehrlichia is not on top of their disease list.”

Ehrlichia was first found in Algerian dogs in 1935. Thirty years later, U.S. Army doctors recorded a lethal epidemic among military dogs in Vietnam. By 1986, the doctors documented the first known case of ehrlichia in a human.

Webb started looking for ehrlichia in Orange County two years later after reading an Army advisory on half a dozen soldiers who were infected during training exercises at Ft. Stewart, Ga. While reports of the disease on the East Coast grew more frequent, Webb didn’t find his quarry in California until 1996.

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It remains unclear how significant a public health threat the illness poses.

In most cases, the sickness is similar to a severe flu or mononucleosis, Webb said. It can be fatal to people with weakened immune systems.

Foley is working on a map to track the disease.

“Having a good map is crucial,” she said. “If you live in Riverside, the risk may be minimal, but if you go camping in Santa Cruz County, all of the sudden it’s not so trivial.”

As El Nino rains are replaced by hot summer winds, the tick worries will quite literally dry up with the vegetation. But until then, hikers should be watchful for tiny parasite seeking a fleshy spot for dinner.

“Right now, it’s very bad,” Foley said. “We were out flagging [collecting ticks on a flannel cloth] and there were so many ticks. When the ticks are out in force and you go hiking in the hills, you will get covered.”