Can Ticks Spread Hepatitis C Virus?

November 20, 2002 02:08:08 PM PST, HealthScout News

 

By Adam Marcus
HealthScoutNews Reporter

 

WEDNESDAY, Nov. 20 (HealthScoutNews) -- Everyone knows that ticks spread Lyme disease. But hepatitis C virus?

Scientists at the American Red Cross say they've made a circumstantial case for a tick passing the infection to a Connecticut woman who had no other obvious means of contracting the liver-damaging malady.

"Ticks obviously ingest a fair amount of host blood and re-inject blood into the next animal or person they bite. They at least could act like little syringes," says Dr. Ritchard Cable, medical director for the Red Cross's blood services center in Farmington, Conn. He and his colleagues describe the case in a research letter in tomorrow's issue of The New England Journal of Medicine.

Cable admits the connection could be coincidence. He has seen no other evidence of ticks ferrying hepatitis C from one person to another, nor to a person from an infected animal -- assuming that animals can contract the virus. What's more, it's not even clear the microbe can survive in ticks.

Still, they have no better explanation for how the woman picked up the disease. She denies being infected on the job or having any high-risk lifestyle habits, such as multiple sex partners or drug use.

The woman, a health-care worker and regular blood donor, was participating in a 1999 Red Cross study of a disease called babesiosis that's transmitted by deer ticks. Blood she gave in July 1999 tested positive for that disease, but not for hepatitis C.

Yet when the woman gave blood five months later, hepatitis C appeared, a highly unusual event in regular donors. An August blood sample drawn as part of the study also turned up genetic evidence of the virus upon re-examination.

When doctors spoke to the woman, Cable says, she revealed that she'd been ill in September with symptoms that were consistent with hepatitis C, including fatigue, stomach cramps, loss of appetite and dark urine. Intriguingly, she seemed to have acquired the infection during roughly the same window of time that she also picked up babesiosis, he says.

Ticks do transmit at least one virus related to hepatitis C, causing tick-borne encephalitis, says Tom Schwan, an expert on the creatures at the National Institutes of Health's Rocky Mountain Laboratories in Hamilton, Mont. In Africa, ticks on rare occasions shuttle a disease called relapsing fever from person to person.

Even so, Schwan says catching hepatitis C from a tick bite would be "an extremely rare event that assumes many things" -- including that the parasites are suitable hosts for the virus. "I would be very cautious" about concluding that the Connecticut case isn't one of mistaken infectivity, he adds.

Hepatitis C, which can lead to fatal liver damage, affects nearly 4 million Americans. The disease typically causes no symptoms for years, earning it the nickname the "silent killer."

Most infections occur in drug users sharing tainted needles. Screening of the blood supply has driven the rate of transfusion transmission, once a major problem, to less than one case per million units, according to the U.S. Centers for Disease Control and Prevention.

What To Do

To learn more about hepatitis C, try the U.S. Centers for Disease Control and Prevention. For more on the nation's blood supply, try the American Red Cross.