 Oct. 18, 2002 |
| ASSEMBLY EDITION • SAN DIEGO |
Mosquitoes can kill. Ted Epperly, M.D., chair and program director of the Family Practice Residency of Idaho, Boise, wants people to know this.
Just as events of Sept. 11 have alerted people to the possibility of bioterrorism, the recent outbreaks of West Nile virus should be waking people up to the dangers of mosquitoes.
Many people attending his lecture on the topic Wednesday night were keenly aware of this. By a show of hands, about 25 attendees had already seen a case of this rapidly spreading disease in their own practices.
"The point is, this has become a permanent problem. This is here to stay," said Epperly.
Epperly noted that West Nile virus is a disease of birds; human beings are merely incidental targets. The disease is spread by mosquitoes that prey on birds as well as people.
From whence did it come?
It's found widely in the Eastern Hemisphere, having been first identified along the West Nile of Uganda in 1937, said Epperly.
No one knows for sure how West Nile virus came to the Western Hemisphere. Veterinarians in 1999 were the first to notice a mysterious illness that was afflicting crows in New York City. Not long after, five elderly persons, all living within a two-mile radius, became ill with profound muscle weakness and aseptic meningitis, and physicians were confounded. Serum from the afflicted birds was tested on the patients to confirm the virus.
Since then, it has spread rapidly, and now the most common states for human cases are Illinois, Michigan, Ohio, Louisiana and Mississippi. This geographical trend proves the pattern of the disease, said Epperly: It follows the migratory traffic of birds. These states are along what is known as the Mississippi Flyway, although East Coast states along the Atlantic Flyway are not spared. More bad news: Despite dormancy, overwintering mosquitoes maintain the virus until spring. We can expect the trend to pick up where it left off as soon as the vectors become active again, said Epperly.
Things to know
West Nile is from the Flaviviridae family of viruses, which includes hepatitis C virus, and is of the same genus as dengue and yellow fever. Epperly predicted that West Nile will soon have that dubious distinction of being the most common viral encephalitis in the United States.
Risk factors include advanced age and immunosuppression. Up to 80 percent of those with the virus are asymptomatic. A high index of suspicion should be maintained regarding the patient presenting with muscle weakness, fever and headache in late summer or early fall.
Diagnosis is made by ELISA of serum or cerebrospinal fluid. State health departments will run the tests free of charge, said Epperly.
Treatment has included empiric treatment with ceftriaxone, ampicillin and acyclovir for culture negative meningitis. Other drugs have shown no clear evidence of improvement, Epperly noted. Thus, prevention makes most sense.
The fact that the initial victims in New York lived in close proximity bears out the theory that the vectors of West Nile virus don't fly far, said Epperly. People should be vigilant to keep their property clear of standing water, where eggs are laid, and to wear long sleeves and long pants at dusk and dawn.
Epperly encourages physicians to stay current on West Nile developments. The CDC maintains a site, http://www.cdc.gov/ncidod/dvbid/westnile/index.htm, that is an excellent resource, said Epperly.
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Copyright © 2002 by
American Academy of Family Physicians.