With more than a month left in the West Nile virus season, Marylandís health department is reporting 25 human cases of the virus, more than any year since 2003.
Two of the cases have been fatal, although the Department of Health and Mental Hygiene is not releasing information about the patients, such as their ages or where they lived.
Prince Georgeís County, with six cases, has more than any other county in the state. Anne Arundel County and Baltimore city have three each.
In 2003, the last year the number of cases surpassed 25, 73 people contracted the virus. Last year, the state saw 19 cases, including one fatality.
The peak year for West Nile in 2003 was just a couple of years after the virus first appeared in North America, said Kim Mitchell, chief of rabies and vector-borne diseases at the Department of Health and Mental Hygiene.
ďYou see that in a lot of parts of the country where there are naive populations,Ē where the population has never before been exposed to the virus, Mitchell said.
The Maryland Department of Agricultureís Pesticide Advisory Committee will meet Sept. 26 to discuss the stateís mosquito control program. The programís $2.5 million budget covers monitoring and pesticide application for both larvae and adult mosquitoes in 2,100 communities in 16 counties.
Department spokeswoman Julie Oberg said the West Nile outbreak is not a major cause of concern for the committee, as the jump in the number of cases is not as severe as in other states.
West Nile has hit places such as Texas, where more than 1,200 people have been infected and 57 have died, more severely than Maryland, Mitchell said. Nationwide, more than 2,600 cases, with 118 deaths, have been reported, according to the Centers for Disease Control and Prevention, which called this year the worst since 2003.
Mitchell said she canít point to a single factor or cause of the jump in cases this year, but the mild winter and relatively dry summer could be factors.
Other contributing factors could be human behavior, the feeding habits of mosquitoes, bird populations and movement and the climate, Mitchell said.
The West Nile surveillance season — the peak season for mosquito activity — ends Oct. 31. Mitchell said she canít predict how many more cases will come in before then.
The good news is that fewer than 20 percent of those exposed to the virus exhibit symptoms such as fever, headaches or rashes, Mitchell said. And less than 1 percent exhibit life-threatening symptoms such as encephalitis, a swelling of the brain, or meningitis, a swelling of membranes around the brain and spinal cord.
Health officials are encouraging residents to get rid of standing water near their homes, such as in bird baths or buckets, and to use insect repellent if out during the peak mosquito hours of dusk and dawn.