Deanna Simon: Fighting the West Nile Virus

Summer is here again. It's back to warmer weather, longer days, backyard barbeques and, inevitably, mosquitoes. This year, it's more important than ever to protect yourself from bug bites because the West Nile virus is expected to reach the Bay Area.

The West Nile virus made its United States debut in New York during the summer of 1999. There have been a few cases reported in Southern California, and the virus is expected to show up in the Bay Area this summer. The chance of infection is quite small, but it's always smart to play it safe.

The West Nile virus is a disease carried by birds - primarily crows, jays, hawks and magpies - but some mosquitoes that feed on infected birds can transmit the virus to human beings. The highest risk is to the elderly and those with weakened immune systems.

The good news is that only a few species of mosquitoes carry the virus and if an infected mosquito bites you, you've only got a 1 in 100 chance of  getting the virus. And of the people who get the virus, only about 1 in 150 may feel ill enough to see a doctor.

The bad news is that there is not yet a vaccine for human beings (only for horses) and treatment consists of  supportive nursing care. Symptoms of serious illness include head and neck pain, high fever, confusion, tremors, muscle weakness, paralysis and, in 264 cases over the past year, death. 

Nevertheless, there are several simple things each of us can do to prevent the virus from spreading. 

San Francisco is getting a jump on the virus by eliminating breeding sources and making sure sewer drains are not blocked and ponds in city parks are stocked with special mosquito-eating microorganisms.

The SF Department of Public Health is working with city agencies to develop a coordinated mosquito prevention and West Nile virus response plan. It also investigates reports from the public regarding problem mosquito activity and works with doctors and hospitals to make sure potential West Nile virus cases are properly diagnosed. Bay Area residents can also lend a hand. The most effective way of preventing West Nile virus is to control the mosquitoes at their breeding source: standing water. Killing adult mosquitoes with poisonous chemical sprays is ineffective because it fails to eliminate their breeding source. Mosquitoes can mature in tiny amounts of standing water - as little as one tablespoon - in just one week.

To prevent mosquito breeding in standing water:

• Eliminate standing water in all containers;

• Keep rain gutters and drains free of debris;

• Drill holes in large containers to let water drain out;

• Report potholes and broken sidewalks to (415) 28-CLEAN (282-5326);

• Fix leaky outdoor faucets;

• Fill tree holes with absorbent, such as SoilMoist or Broadleaf P4;

• Offer to help neighbors who are elderly or disabled with these responsibilities.

For ponds and mosquito prevention install a water pump to keep water moving, add mosquito fish (free from the San Mateo Mosquito Abatement District at (650) 344-8592 or use less toxic controls for the larvae. These include products like MosquitoDunks, Vectobac, Pre-Strike or others that contain bacteria (Bt) or methoprene. You can find these products at neighborhood hardware stores, including Cole Hardware or Sloat Garden Centers.

To protect against bug bites, wear long sleeves and long pants, use insect repellent and consider installing screens. Call the Health Department (252-3805) to report mosquito problems or go to www.sfmosquito.org for more information.

Mosquito Repellent Update
Insect repellents containing DEET are popular because they last for many hours. However, growing health concerns about DEET have led to research on alternative repellents. Recent studies show products containing Picaridin (KBR 3023) or oil of lemon eucalyptus (p-menthane 3,8-diol) also provide long-lasting protection against mosquito bites. 

Other Things the Public Can Do
State and local agencies regularly monitor chicken flocks and dead wild birds for the first signs of the West Nile Virus in an area.  

Call the West Nile Virus hotline (1-877-WNV-BIRD) for information or to report dead birds (especially crows, jays, magpies, and and hawks, sparrows and finches). To access mosquito and West Nile Virus information, go to www.sfmosquito.org.

The SF Department of Public Health is a state certified vector control agency and has been working with key city departments to develop a coordinated mosquito prevention and response plan. Eliminating breeding sources is the top priority and toxic controls are used only as a last resort. The health department will investigate reports from the public regarding problem mosquito activity and they are in communication with health care providers regarding proper diagnosis and care of patients suspected of having the West Nile Virus.

Deanna Simon coordinates toxic chemical reduction programs for SF Environment. For more information, call 355-3700.