California is suffering its worst drought since white settlement began in the region. It also appears that cases of illness due to the West Nile virus will also be setting records. The two occurrences are probably related, according to Dr Cameron Webb of the University of Sydney in Australia.
What is the relationship between drought and West Nile? The virus is carried primarily by various Culex mosquito species, and birds are the reservoir for the virus. Female mosquitoes bite, and the blood is used the ensure that they can reproduce. It is a disease of birds and those people, horses and other animals who contract the illness are secondary for the feeding mosquitoes.
In a drought, places where people live and work are going to have water when the wilderness does not. Birds are drawn closer to human habitation to find water and food. The mosquitoes follow the birds.
Don’t mosquitoes need water to breed? Yes, they do, but Culex species are very tolerant of polluted water. Containers that hold a lingering amount of water are the usual breeding site but storm sewers provide an ideal breeding location during a drought. At the lowest levels of the sewers, small pools of water will exist and attract the mosquitoes.
California saw its second highest number of West Niles illnesses reported in 2014, with 801. The number of West Nile neuroinvasive disease (WNND) illnesses recorded was 561. 31 patients died of their illness.
The Centers for Disease Control have estimated that for every case of WWND, between 150 and 250 cases of the less severe illness are contracted. That would mean between 84,000 and 140,000 Californians caught the mosquito-transmitted illness in 2014.
Fortunately, 80 percent of those infected with the West Nile virus experience extremely minor symptoms or none at all. Unfortunately, because this is an illness of wild birds, it is unlikely that the illness will ever vanish.
Vaccines are in the works but none have been approved for use at this time. Preventing mosquito bites are the best way at this time of avoiding contracting a West Nile illness.
- Use mosquito repellant.
- Wear long sleeves, long pants and socks when practical.
- Ensure that windows and doors have screens with mesh small enough to keep mosquitoes out. Repair or replace any broken or torn screens immediately.
- Support mosquito control efforts in the community. Sanitize your outdoor space by removing anything that can catch and hold water, fully drain swimming pools and ensure that roof drains and gutters are clean and free of puddles and pools of water.