BY JANE STOEVER & CINDY BORGMEYER
Not long ago, most of us considered mosquitoes little more than a minor annoyance. Unfortunately, that's no longer the case.
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Mosquitoes infected with the West Nile virus usually get their "blood meals" by biting birds, and the birds are carrying the virus relentlessly toward the West Coast, Ted Epperly, M.D., told Assembly-goers Oct. 5.
That is spelling big trouble for the folks living out West.
Last year, the five top states with the virus were Illinois, Michigan, Ohio, Louisiana and Indiana. This year, by early October, the top five were Colorado, Nebraska, South Dakota, Texas and Wyoming.
Unlike 2003's other headline-grabbing infections -- severe acute respiratory syndrome, or SARS, and monkeypox -- West Nile is here to stay. "Monkeypox was one and done," Epperly stated flatly. "It's a 50-50 bet on whether SARS will re-emerge this year, and the World Health Organization has already been invited to help monitor and suppress SARS if it resurfaces in China. But West Nile is permanent."
Epperly is director of the Family Practice Residency of Idaho, Boise, and immediate past chair of the AAFP Commission on Education. Most of his lecture and the audience's questions zeroed in on West Nile.
Culex and other types of carrying mosquitoes fly only half a mile in their lifetime; they don't migrate. Birds do migrate, however, and "the disease is following bird migratory patterns," Epperly said. "Birds and mosquitoes continue to bite and infect each other. They spin it up among each other. These vector mosquitoes are looking for birds and searching for birds. But once the burden of the virus is high enough, bridge-vector mosquitoes spread the virus to other things -- humans, horses and other animals."
This year, the virus has gone gangbusters, he noted. "We could easily hit 8,000 to 9,000 cases this year, compared with 4,156 total cases last year." By early October, 133 people had died of West Nile; last year's total number of deaths was 284. Epperly advised checking http://www.cdc.gov/ncidod/dvbid/westnile/surv&control.htm for updated information.
Given the generally lower incidence of West Nile this year in states where it was strongest last year, Epperly suggested birds may become immune to it and stop transmitting it. "It may become a low-level disease," he said, noting that immunity to West Nile in humans looks to be lifelong.
Four out of five persons infected with West Nile show no symptoms, he said, and the vast majority of those who become symptomatic suffer only a mild flu-like illness known as West Nile fever.
Only 0.6 percent of those infected with the virus develop West Nile disease, characterized by severe and progressive neurologic signs and symptoms, said Epperly. Treatment for these patients is supportive, and the mortality rate ranges from 5 percent to 14 percent.
Three patient groups are at particular risk: people older than 70, people with diabetes and people who are immunosuppressed.
Diagnosis starts with an exposure history in patients with suspicious symptoms. "The hallmark for us as family physicians is this: a fever at the wrong time of year, one that lasts three to six days," he said. State health departments provide free enzyme-linked immuno-sorbent assay, or ELISA, testing for West Nile. It takes about 24-48 hours to get the IgM antibody test results back. The FDA has recently approved a new IgM ELISA test that will detect antibodies in about two hours.
Encourage patients to adopt a three-pronged prevention strategy, Epperly said. Wear long sleeves and pants at dusk and dawn. Use DEET, or diethyltoluamide, to fend off the mosquitoes. Third, drain off any freestanding water.
Regarding SARS and monkeypox, Epperly said, "Here were two relatively rare outbreaks that gained notoriety because of widespread publicity. It's a two-edged sword: The publicity may have helped shut down a worldwide epidemic, but along with that came a lot of anxiety."
What's become clear is the importance of FPs having a good working knowledge of the public health system -- knowing what number to call to get questions answered or tests performed, Epperly said. "If there's been a positive side to all this, it's been the re-emergence of the importance of public health departments and the CDC working together to educate people -- the CDC to educate the nation, public health departments to educate doctors and the community, and doctors to educate patients."
FP Report is published by the
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Copyright © 2003 by
American Academy of Family Physicians.