CC MEETING: July 26, 2016
DATE: July 16, 2016
TO: Leonard Martin, City Manager
FROM: Scott Hudson, Environmental Services Director
Title
Discuss The Carrollton Vector Control Program Relating To Mosquito-Borne Illnesses.
Body
BACKGROUND:
West Nile Virus
Since 2002 West Nile virus (WNv) has been endemic to the Dallas-Fort Worth metropolitan area and cases of West Nile illness were reported sporadically in Carrollton through 2011. This virus is spread by mosquitoes and causes two principal illnesses. The effects of West Nile fever are variable but generally short-term, comprised mainly of flu-like symptoms such as body aches and fatigue. West Nile neuroinvasive disease causes severe central nervous system symptoms including long-term partial paralysis. Most WNv-related fatalities result from neuroinvasive disease. The majority of people infected with West Nile virus do not appear to become ill.
In 2012 an epidemic of West Nile fever and West Nile neuroinvasive illness occurred in Texas, centered heavily in the Dallas area. Cases reported in Texas totaled 1,868, including 1,024 West Nile fever, 844 West Nile neuroinvasive, and 89 deaths. Of these, 26 cases occurred in Carrollton (15 West Nile fever, 11 West Nile neuroinvasive), including one death. Bearing in mind that only some 20% of the people infected become symptomatic and that symptomatic cases are under-reported, the statewide infection rate was significantly higher than these numbers reflect. Carrollton participated in regional aerial mosquitocide spraying in 2012.
Local conditions have been very favorable for mosquitoes this year. Numbers of mosquitoes trapped and numbers of mosquito traps testing positive for WNv were very high early in the season. These numbers have decreased over the last two weeks but could rise again as the season progresses. There have been three reported WNv cases in Dallas County this year, one of these being a neuroinvasive case in Carrollton.
For over 30 years Carrollton has participated in a regional mosquito control program with Dallas County and area cities. This focuses on surveillance (inspections and trapping), public education, and application of larvicides and adulticides. Following the 2012 epidemic the U.S. Centers for Disease Control provided guidance reshaping this program, primarily to improve surveillance and statistical analysis and to better coordinate preventive efforts.
Carrollton is continuing its monitoring and targeted spraying WNv control efforts.
Zika Virus
In 2015 incidence of Zika-related illnesses began to increase dramatically, especially in South and Central America where the virus is transmitted locally. Reported cases of Zika virus have become common in the United States this year. To date, all documented U.S. Zika virus cases have been travel-related, i.e. the virus was brought in from outside this country.
Disease caused by the Zika virus is spread to people primarily through the bite of an infected mosquito. The illness is typically mild with symptoms including fever, rash, joint pain and conjunctivitis. These last up to a week; many people do not have symptoms or have only mild symptoms. However, Zika virus infection during pregnancy can cause several birth defects including microcephaly, a serious condition in which the baby’s head is smaller than normal. The virus is also linked to an uncommon nervous system illness, Guillain-Barré syndrome.
There have been 13 confirmed cases of Zika virus in Dallas County this year. Two cases have appeared in Carrollton. Expanding from its existing programs, the city has added Zika virus surveillance and educational components, coordinating with regional efforts. Carrollton is following Centers for Disease Control guidance in responding to these cases to prevent local transmission.