State of Maryland West Nile Virus
Control Plan
Introduction
West Nile Virus, though know since 1937, had never before emerged in the United States. Then, in late August and September of 1999, about 60 people in New York and surrounding areas became sick; seven people died. This virus has raised many questions, especially: Is it a threat to Maryland? What can be done to control it? The following plan explains the different aspects of West Nile Virus and what is being done about it.
West Nile Virus (WNV) is a virus that is transmitted by mosquitoes. There are a number of viruses transmitted by mosquitoes and monitored by public health agencies in the United States. These viruses include Eastern Equine Encephalitis, St. Louis Encephalitis, Western Equine Encephalitis, and LaCrosse Encephalitis viruses. West Nile Virus, which usually occurs in birds, was first identified in this country in the summer of 1999. A mosquito can pick up the virus when it feeds on an infected bird's blood. Then the mosquito can carry the virus and infect a person by biting her or him. A mosquito that carries WNV can also infect other birds, horses, and possibly other animals. As far as health authorities know at this time, a person cannot get WNV infection directly from birds, horses, or another person.
For most people who have been exposed to it, WNV causes no symptoms at all. In some people, WNV can cause a very mild infection including fever, muscle aches, rash, swollen lymph nodes, and a "sick" feeling. This illness starts about 5-15 days after the mosquito bite, then lasts a few days, and finally goes away on its own.
In a very small fraction of people exposed to WNV, it can cause an inflammation of the brain (encephalitis) or the tissues that surround the brain (meningitis). Encephalitis and meningitis due to WNV can cause death. In the New York area outbreak late last summer, deaths from WNV infection occurred among elderly persons (greater than 60 years of age). Why some people seem to get seriously ill from WNV, while others don't, is being studied.
The following pages describe Maryland?s plan to control West Nile Virus through surveillance, education and evaluation.
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Mosquito Surveillance
Purpose:
Mosquito populations are essential to the spread of WNV. Therefore, it is important to monitor the abundance of various mosquito species throughout the State. It is also important to study mosquitoes to see if they are carrying the West Nile Virus. The reason for this is to find out if they might be able to infect a person when they bite.
Actions:
1. During the mosquito development season, the Maryland Department of Agriculture (MDA) Mosquito Control Section, which is the State agency in charge of mosquito control, will use special equipment to trap mosquitoes in various places around the State. The document, "WNV Surveillance in Maryland: Maryland Department of Agriculture: Plan of Activities" contains additional detailed information.
2. The mosquitoes that have been trapped will be examined to determine the number and type of mosquitoes in that area.
3. The trapped mosquitoes will then be sent for testing to the Maryland Department of Health and Mental Hygiene (DHMH) Laboratories Administration, which is the State's Public Health Laboratory. DHMH laboratory scientists will check mosquitoes for the presence of West Nile or other disease-causing viruses.
4. When testing is complete, results will be sent to the DHMH Center for Veterinary Public Health's Division of Rabies and Vector-Borne Diseases, the State agency in charge of monitoring diseases that can be transmitted to people by mosquitoes or other vectors. There, the results will be entered into a special database. Information on mosquito density and distribution will be collected by field studies and will be analyzed in conjunction with mosquito test results. These results will help us identify areas of risk for virus transmission in each jurisdiction of Maryland.
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Mosquito Control
Purpose:
To prevent mosquitoes that carry WNV from infecting humans, it is important to use pest management techniques to prevent the growth of mosquitoes in Maryland. The way mosquitoes are controlled is described below.
Actions:
1. The Maryland Department of Agriculture Mosquito Control Section, the State agency in charge of mosquito control, will continue its program to control mosquito activity in Maryland, as it has done for many years.
2. If WNV is found in mosquitoes in Maryland, or if human or animal cases of WNV are found, an assessment will be done on whether this infection may be an immediate threat to the health of Maryland residents. Depending on the locations, kinds and numbers of mosquitoes found to carry WNV, the MDA Mosquito Control Section will begin more intensive, focussed mosquito control efforts. The document, "WNV Surveillance in Maryland: Maryland Department of Agriculture: Plan of Activities" contains additional detailed information.
3. A public education campaign will be conducted and will emphasize several items:
· The general public is at low risk.
· How to reduce risk of getting bitten by a mosquito (use of repellents, wearing clothing on extremities, staying indoors at dawn and dusk).
· How to eliminate places where mosquitoes can develop around homes and apartments.
· Where to call for further information.
· If mosquitoes in a given area are found to have WNV, this educational campaign will be focussed more directly to that area.
4. Mosquito control efforts will continue to be coordinated with mosquito testing results and other indicators of WNV in Maryland. A summary of mosquito control activities will be recorded by the MDA Mosquito Control Section and sent to DHMH Center for Veterinary Public Health.
5. Mosquito control efforts will stop when the weather becomes consistently cold enough to prevent further mosquito activity.
6. Planning for mosquito control efforts in the 2001 season will include the recommendations of the evaluation of 2000 season performance (see "Evaluation of Control Efforts.")
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Dead Bird Surveillance
Purpose:
Wild birds (such as crows) can be infected by WNV. Some of these infected birds may die of WNV infection. Maryland State agencies will check selected dead bird specimens to find out if the death was caused by WNV infection. Together with other sources of information, these findings from dead bird surveillance will help us understand the patterns of WNV infection (if any) in Maryland. The help of the public will be requested to find out where wild bird deaths have occurred. Maryland Department of Natural Resources hotline personnel will then decide whether a particular dead bird specimen should be retrieved and tested for WNV infection.
Actions:
1. The Maryland Department of Natural Resources (DNR) Police together with DHMH will operate a 1-800 hotline for the public to report wild bird deaths in Maryland. This hotline (and how to call it) will be publicized in the initial public information campaign (see separate section below). The hotline will inform callers that dead birds cannot transmit WNV infection to human beings or to animals. Information about reported bird deaths will be collected using the "DNR West Nile Virus Report Form."
2. If the dead bird is considered worth testing, the report will be referred to a local public health department that will coordinate the pickup and examination of the dead wild bird(s) based on information supplied by the caller.
3. Not every dead bird reported will be selected for examination. Many bird deaths have no relationship to WNV disease. Sometimes, decomposition of the bird prevents successful examination.
a) Depending on the dead bird's condition and the circumstances in which it was found, the caller may be asked to throw the dead bird's body away in an appropriate manner.
b) However, if the dead bird is selected for examination, and if the caller is willing, they will be instructed how to safely put the body into a plastic bag on ice. The dead bird's body will be picked up and delivered for testing by the local health department to DHMH Laboratories Administration, Baltimore, according to instructions provided by the laboratory. The Maryland Department of Natural Resources will provide instructions to DHMH laboratory scientists on how to recognize the signs of WNV or other infection in the dead bird's body.
4. Results of testing of dead birds will be collected and analyzed by an epidemiologist at DHMH Center for Veterinary Public Health.
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Avian Surveillance
Purpose:
Wild and domestic birds can be infected by WNV. Some of these infected birds develop antibodies to WNV infection. These antibodies can be detected in a laboratory test, and can be used to study WNV in birds. Combined with other sources of information, these findings will help detect patterns of avian exposure to WNV.
Actions:
1. The Maryland Department of Natural Resources (DNR), the State agency which monitors the health of wildlife in Maryland, will obtain blood samples from wild birds for WNV testing.
2. When chickens become infected with WNV, they develop antibodies to the virus but do not become ill. MDA will establish flocks of chickens and will regularly draw blood specimens to monitor for virus activity. The document "WNV Surveillance in Maryland: Maryland Department of Agriculture: Plan of Activities" contains additional procedural information. At this point there are no known adverse effects of WNV on commercially produced chickens or on fully cooked chicken food products. The blood samples from domesticated and wild birds will be sent for testing to the DHMH Laboratories Administration or to the National Wildlife Health Center. Tests may take several weeks to complete.
3. Results of testing of wild and domesticated birds will be collected and analyzed by an epidemiologist at Department of Health & Mental Hygiene-Center for Veterinary Public Health.
Note: Measures to protect exotic birds involve preventing mosquito exposures.
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Equine (Horse) Surveillance
Purpose:
In last year's outbreak, some horses in eastern Long Island were infected with WNV. Horses are an important part of Maryland's economy. It is important to alert veterinarians about WNV disease, and about how to test horses if WNV or other serious disease is suspected.
Actions:
1. DHMH and MDA will notify veterinarians about WNV infection in horses. The notification letter will tell veterinarians what kind of illness to look for, and how to test the horse for WNV or other serious viral infections. The document, "WNV Surveillance in Maryland: Maryland Department of Agriculture: Plan of Activities contains additional information.
2. If a horse is suspected of having WNV infection, veterinarians will be asked to collect appropriate specimens.
3. Results from testing of horse blood samples may take several weeks to complete.
4. Necropsies (careful examinations of the bodies of dead horses for disease) will be offered free of charge to owners of horses whose deaths suggest WNV or other serious diseases causing encephalitis are suspected as the cause of death. Laboratories of the MDA will perform necropsies of horses when WNV or other causes of encephalitis are suspected as the cause of death.
5. Results of horse blood testing and of horse necropsies will be collected and analyzed.
Note: Protection of horses involves keeping horses stabled inside during high mosquito feeding times, i.e., dusk and dawn. Insect proofing of stables and use of repellents are strongly recommended. There is no vaccine available
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Human Surveillance
Purpose:
Studies of the New York outbreak last year showed that many hundreds or even thousands of people were exposed to WNV, but only a small percentage of them became seriously ill. Encephalitis, an inflammation of the brain, is the most serious form of WNV infection. However, other diseases can cause encephalitis. In Maryland, any case of human encephalitis will be studied very closely. These studies may include blood tests or tests to detect WNV in the brain or the spinal fluid. The human surveillance effort will be important to find out if WNV disease is present in Maryland. This information will help public health officials and other state agencies decide how to control this serious disease.
Actions:
1. To make sure that doctors and other health professionals know about WNV disease, DHMH Epidemiology and Disease Control Program will provide professional education to hospitals and interested medical and nursing groups in Maryland.
2. Doctors will be reminded that encephalitis and meningitis can be indicators of WNV infection. They will also be reminded that any case of either encephalitis or meningitis must be reported to their local health department no later than the next working day.
3. Local health department staff will receive updated guidelines on investigating any reported case of encephalitis and (as time permits) meningitis. This will make sure that the proper testing is done to find out what the cause of each case is. Local health departments will assist doctors in getting testing done by the State Public Health Laboratory.
4. Local health departments will promptly send basic information on each reported case of encephalitis to DHMH Division of Communicable Disease Surveillance in Baltimore. Epidemiologists will collect and analyze the number and types of cases of encephalitis, and what pattern of spread each type of disease may be showing.
5. Special examination of tissues from persons who are suffering from, or who have died of encephalitis will be offered through hospital pathology departments and the Maryland State Public Health Laboratory. Results from testing of human blood or tissues may take several weeks to complete.
6. Results of human blood and other testing for WNV and other serious viruses will be collected and analyzed by epidemiologists of DHMH Division of Communicable Disease Surveillance.
7. Information will be provided to medical providers and public health departments as necessary.
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Public Information Campaign
Purpose:
Among other things, the Maryland public needs to be kept well informed about what is happening with WNV infection, and what is being done to control it. The public's assistance will be requested in helping reduce WNV risk and in locating deaths among wild birds.
Actions:
1. DHMH, DNR, and MDA will provide media briefings on West Nile Virus disease, the Maryland plan for West Nile Virus control, and information on how to contact the WNV hotline.
2. The Center for Veterinary Public Health will update the public information materials prepared last fall, concerning West Nile Virus infections, and how to minimize mosquito exposure. These documents will be made available electronically through the DHMH web site and through local public health departments throughout the State.
3. Representatives from different State agencies will be assigned to answer questions from the public media as appropriate for the request received. The public relations offices of DHMH, DNR, and MDA will handle coordination of media requests.
4. The 1-800 hotline will provide information and respond to questions about WNV and Maryland surveillance and control measures.
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Evaluation of Control Efforts
Purpose:
To make sure that State agencies are working effectively to control WNV infection, an evaluation program to examine the success of the West Nile disease control activities will be supported. A report of the findings of this evaluation will be distributed to the heads of the State agencies involved.
Actions:
1. Indicators of the effectiveness of the WNV control efforts have been developed. These indicators include:
Effectiveness of mosquito control
Completion of testing for WNV and other arboviral diseases
Indicators of WNV in a mosquito; in an animal host; or in a human being; including both laboratory studies and information about cases and (if any) deaths
Number and types of education activities to reach out to Maryland residents concerning both personal exposure control and arboviral disease recognition
2. There will be a monthly review of indicators and their implications by representatives of all three State agencies, led by DHMH-CVPH. These monthly review sessions will start in May 2000 and finish in November 2000.
3. Findings of these evaluation sessions will be reported to the Secretaries of DHMH, DNR, and MDA. A final evaluation report, including recommendations for WNV surveillance and control activities during CY2001, will be issued by February 1, 2001.
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Summary
1. The Maryland Departments of Health and Mental Hygiene, Natural Resources, and Agriculture will continue to work collaboratively under the direction of the Governor's Office to carry out the above plans to detect and control West Nile Virus infections in Maryland.
2. These three State agencies will periodically review progress toward implementing this plan. The three departments, in consultation with national health authorities, will also assess the plan's effectiveness in WNV detection and control, in an evidence-based, multidisciplinary process. Information collected will be used to target areas where problems are detected and to refine efforts. Interim recommendations for additional or modified program activities in a state department will be reviewed and approved by the Secretary of that department before implementation.
3. The Governor’s Office will be kept appraised of findings on a regular basis. They will also be provided with recommendations for next year’s detection and control efforts.
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