The Mississippi State Department of Health (MSDH) announces the fourth human case of West Nile virus for 2008 just in time for National Mosquito Control Awareness Week, which is this week. The new case is in Madison County where another one of this year’s cases was confirmed, along with one each in Lincoln and Forrest counties. MSDH reports confirmed and probable cases to the public.
State Epidemiologist Dr. Mary Currier says that just because cases aren’t reported from other counties doesn’t mean the virus is not there. Likewise, having two cases in a county doesn’t mean it’s a hot spot for West Nile. The months of July, August and September are peak mosquito reproduction time. MSDH will conduct its most intensive surveillance during those months.
“West Nile virus is most prevalent in mid- to late summer but can occur throughout the year,” she said. “It’s very important for people to take appropriate precautions when they’re outside, especially with the long Fourth of July weekend coming up. Wearing protective clothing and spraying ourselves helps.
“As Mississippi families enjoy outdoor activities this summer, especially at dusk, it is important that everyone take steps to protect themselves both personally and environmentally.”
Those environmental precautions include removing sources of standing water and avoiding mosquito-prone areas, especially between dusk and dawn when mosquitoes are most active. “Water that doesn’t move is what we’re talking about,” she added. “Moving streams are okay, but they can be treated with environmentally correct products, too, that don’t kill fish.”
Symptoms of West Nile virus infection are often mild and may include fever, headache, nausea, vomiting, a rash, muscle weakness or swollen lymph nodes. In a small number of cases, infection can result in encephalitis or meningitis, which can lead to paralysis, coma and possibly death.
Approximately 20% of those infected with the virus will get some illness and most of those are mild. The percentage experiencing more serious illness is very small — less than 1%, Currier said.
“Older people and those who are immune repressed are more at risk for having severe disease,” she said, “but young people can get it, too.”
This mosquito borne virus was first found in Mississippi in 2001 in an infected horse. Last year, there were 136 cases and four deaths for the whole season. Currier stresses that some cases may not be diagnosed or reported.
So far, the worst year was 2002 with 193 reported cases and 12 deaths. In 2003, there were 83 cases and two deaths, 52 cases and four deaths in 2004, 70 cases and six deaths in 2005 and 184 cases and 14 deaths in 2006.
“We can’t say what kind of season we’ll have this year,” Currier said. “It’s hard to predict a pattern.”
State Medical Entomologist Dr. Jerome Goddard, who’s affectionately known as the “Bug Man” at MSDH, says there are several insect repellents that work.
“Those that are DEET based are the gold standard,” he said. “They have a great safety record, and there are some new products available along with some herbal products that work, too.”
He cautions there’s no evidence that sonic repellents work, including the ones that are worn as a necklace. “They’ll kill a few mosquitoes but not enough to be effective,” he said. “Citronella candles have some repellent, but are not real effective, either. There are plastic bracelets with repellent embedded in them, but they don’t provide any broad coverage.”
Goddard said the department has received calls about electric mosquito machines that cost several hundred dollars. “I don’t know if they make a difference,” he said. “It’s best to stick with things we know work and use good personal protection.”
There is also an e-mail circulating that advises people to spray their lawns with a popular mouthwash product. That method, Goddard said, is just folk lore.
Contact MBJ contributing writer Lynn Lofton at firstname.lastname@example.org.