IMAGE: The yellow fever mosquito Aedes aegypti. Public domain photo by James Gathany, Centers for Disease Control and Prevention.
BY BILL BROWN
FEB 12 — The chances are remote, but conditions exist for an outbreak of Zika virus in Takoma Park. But, even if it happens, it may not be such a big deal.
The mosquito species that can spread the virus lives here. If a local resident picks up the virus while traveling, brings it back to Takoma Park in their bloodstream and is bitten by one of these mosquitoes – the city could have an outbreak.
Zika virus, however is rarely life threatening, and does not usually require hospitalization. Despite avid media attention to potential links to birth defects, those links are not proven.
Takoma Park is home to a robust population of mosquito species responsible for spreading the Zika virus in South and Central America. The city was at the center of an Aedes aegypti mosquito infestation in 1995 – as reported at the time in the Takoma Voice and the Washington Post. An invasive species, Aedes aegypti breeds in standing water, thriving in areas with open containers, old tires or other places water collects.
The city’s mosquitoes do not carry the virus unless they have bitten a person with the disease. There have been no known occurrences of Zika virus in Takoma Park or Maryland. However within the last year 52 Americans have traveled to other countries, contracted the virus and brought it home with them in their bloodstream. As of yet, there have been no instances of local mosquitoes picking up the virus from these individuals and spreading it.
Though the virus is rarely life-threatening, there is a concern that it may be linked to a serious brain defect called microcephaly in babies of mothers infected with Zika virus while pregnant. The CDC is careful not to say there is a definite link. Their website says “knowledge of the link between Zika and birth defects is evolving.”
Until more is known, however, the CDC recommends pregnant women take special precautions to avoid Zika infection.
There have been three cases of travel-bourne Zika in the District of Columbia, and one in Virginia. There have also been two in Pennsylvania and one in Delaware.
Popular travel destinations where the virus has been detected include the US territory of Puerto Rico, the US Virgin Islands, Jamaica, Martinique, Costa Rica and St Martin. The virus is also found in Mexico, Brazil and several other American countries south of the US.
Color print of the yellow fever mosquito Aedes aegypti. To the left, the male, in the middle and on the right, the female. Above left, a flying pair in copula. Public domain illustration by Emil August Goeldi (1859 – 1917). – E. A. Goeldi (1905) Os Mosquitos no Pará. Memorias do Museu Goeldi. Pará, Brazil.
Though chances are slim, there is a potential for the virus to spread, and it could happen very quickly, said Daniel Schamberger, acting director of the state Agricultural Department’s Mosquito Control Administration
For an outbreak in the continental US to occur, Center for Disease Control spokesperson Benjamin Haynes said, “people infected with a virus need to enter the United States. An Aedes mosquito must bite the infected person during the relatively short time that the virus can be found in the person’s blood. The infected mosquito must live long enough for the virus to multiply and for the mosquito to bite another person.”
The disease is spread by “multiple blood meals,” said Schamberger. Aedes aegeypti females feast several times through their 8 – 10 day life cycle. Their range is only around 100 yards, however.
According to CDC information available online the Zika virus is spread primarily through the bite of an infected mosquito. Death from Zika is extremely rare. Only one in five people infected with Zika virus become ill. Common Zika symptoms are fever, rash, joint pain, or conjunctivitis (red eyes). Other common symptoms include muscle pain and headache.
The illness, according to the CDC, is usually mild with symptoms lasting for several days to a week. It rarely requires a hospital visit. Zika virus persists in the blood of an infected person for about a week but it can be found longer in some people. There is no vaccine or cure for Zika virus.
Spokesperson Haynes said the CDC cannot predict how much the Zika virus could spread in the US, or if it could take hold in Takoma Park. “Many areas have the type of mosquitoes that can become infected with and transmit the virus, however recent chikungunya and dengue outbreaks in the US suggest that Zika outbreaks in the continental United States may be relatively small and focal.”
According to an online statement from Center for Disease Control director Tom Frieden, “We could see isolated cases and small clusters of infections in other parts of the country where the mosquito is present. But from the information we know now, widespread transmission in the contiguous United States appears to be unlikely.”
Frieden says, “For a disease such as Zika to spread widely, two things are necessary. The first is the specific mosquito species that spreads the virus. The second is the conditions in communities; places that are crowded and don’t have air conditioning enable viruses such as Zika to spread.”
Takoma Park has ample air conditioning, but it also has ample breeding conditions, as the persistent Aedes aegypti population attests.
Takoma Park mayor Kate Stewart said she was briefed on the regional approach to Zika at last Wednesday’s Metropolitan Council of Governments board meeting. As a local mayor she is a member of the board.
The meeting was briefed by local health officials. They told the board that thanks to protocols set up during the ebola virus outbreak, local hospitals are well prepared to deal with Zika if it strikes locally. Mosquito control was mentioned, but not in great detail, said Stewart.
The health officials were Preetha Iyengar, Supervisory Epidemiologist at the District of Columbia Department of Health and Reuben K. Varghese, Health Director & Division Chief, Arlington County.
Takoma Park city manager Suzanne Ludlow said that thanks to an alert resident who contacted her about it, she is aware of the mosquito issue. But, she said she has not yet been contacted by any state, county or other outside agencies about mosquito control, she said. In years past, she recalled, the state sprayed the city, avoiding the homes of people who didn’t want it.
Public Works Dept. director Daryl Braithwaite said that during the West Nile Virus alert a few years ago, the city set up a hot-line residents could call to request a survey of their property. A city employee would go to the property, point out potential mosquito breeding areas and advise how to deal with them.
Her department also has not been contacted by any outside agency about mosquito control this spring, she said.
State authorities are aware of the issue and are beginning to gear up, however, according to the director of the agency responsible for state mosquito control.
Efforts will include mosquito trapping and surveillance, said Schamberger, Maryland’s Mosquito Control Administration director. Takoma Park will be one of the areas this will occur, he said,
Spraying is an option, but there will be an emphasis on clearing up Aedes aegypti breeding grounds: containers and anywhere water can collect and remain standing.
Use of genetically modified male mosquitoes whose offspring die before before they can breed has been discussed, but the method is considered experimental and is not under consideration at this time, said the director.
Enforcement of the Takoma Park housing code would assist this effort, said Schamberger.
He said the public will see mosquito control information and efforts starting in March and April.
The Aedes Aegypti mosquito, also known as the “yellow fever mosquito” is a host for several tropical fevers including dengue fever and West-Nile Virus. Since those diseases are not currently present in Takoma Park, the local mosquito population does not currently carry any of these fevers or viruses.