Greenbook: A Local Guide to Chesapeake Living -Issue 11 | Page 59

The Maryland Department of Agriculture (MDA) and
the Maryland Department of Health and Mental Hygiene
(DHMH) collaborate to detect mosquito-borne viruses of
public health concern. Specifically, these agencies moni-
tor the occurrence of Zika Virus, eastern equine enceph-
alitis virus, West Nile virus, St. Louis encephalitis and
other viruses in mosquitoes, wild birds, domestic animals
and humans.
WEST NILE VIRUS. Multiple studies by the Maryland
Department of Health and other agencies have shown
that Tiger mosquitos transmit the causative agent of
dog heartworm disease, eastern equine encephalitis vi-
rus, dengue fever and Japanese encephalitis. Laboratory
studies found the Tiger mosquito to be an efficient vector
of other viral disease agents including yellow fever, West
Nile virus and LaCrosse encephalitis. West Nile virus has
affected every region of Maryland and is now considered
as being endemic throughout the state.
Most individuals infected with West Nile Virus will not
have any symptoms. People that do develop illness usu-
ally will have any combination of fever, headache, body
aches, skin rash and swollen lymph glands. These symp-
toms generally appear two to 14 days following the bite
With the rise in the diagnoses of Zika virus in the
United States, the Maryland Department of Agriculture
(MDA), Mosquito Control Section, has stepped up on ef-
forts to identify, administer and implement mosquito con-
trol protocols. Some of their efforts include reduction at
the source via larvicide and insecticide, biological control
initiatives and public education.
LARVICIDING is the use of insecticide to kill larval mos-
quitos and is the most efficient form of temporary control.
It is more efficient to eradicate or substantially diminish a
brood of mosquitoes while they are concentrated as larvae
than to control them as adults. Kurt calls larvicide mosquito
birth control. “The World Health Organization approved
the use of larvicides more than 25 years ago, when they
started using it to treat drinking water in Africa,” he says.
“Prevention is the single most important aspect of mosquito
safety. Prevention is much easier than eradication.”
of an infected mosquito. Fewer than 1 percent of people
exposed to the virus will develop more severe infections,
with symptoms such as a headache, high fever, neck stiff-
ness, stupor, disorientation, coma, tremors, convulsions,
muscle weakness and paralysis. In rare instances, West
Nile Virus can be fatal. People older than sixty have the
greatest risk of developing severe disease. People with
compromised immune systems also may be at high risk
for West Nile Virus infection.
ZIKA. West Nile Virus is not to be confused with the Zika
virus, which is spread via a different species of mosquito.
No cases of Zika have been reported in Maryland, but the
Center for Disease Control (CDC) has published maps
that show the presence and high likelihood of survival for
the mosquito proven to be a vector for Zika (Aedes aegyp-
ti or Aedes albopictus) in Maryland. Kurt notes that the
mosquito that carries Zika would rather live near humans,
where there is plenty of fuel (human blood) for survival of
the species. Therefore, this mosquito thrives in suburban
and urban areas where there are plenty of tires, pots, dis-
carded toys, birdbaths, leafy landscaping and other safe
breeding grounds.
BIOLOGICAL CONTROL. Control of adult mosquitoes us-
ing birds, bats, dragonflies and frogs has been advocated,
but supportive data are anecdotal. The MDA says there is
no documented study to show that bats, purple martins, or
other predators consume enough adult mosquitoes to be ef-
fective control agents. The Mosquito Control Section does
not advocate the establishment of bat boxes by the public
due to the increased risk of human exposure to rabies.
INSECTICIDAL CONTROL is commonly referred to as
temporary control because the non-residual insecticides
used in Maryland provide only short-term reduction of
mosquito numbers. Insecticide applications are made un-
der the supervision of certified pesticide applicators, pest
control category VIII, and regulated by State and federal
laws. No restricted use pesticides are applied in Mary-
land for mosquito control by State or local government
agencies.
Mosquito Larvae