# 5745
After a unusually quiet first six months of the year – no doubt influenced by the prolonged drought across much of the southern tier of states – mosquito borne threats like Dengue fever and West Nile Virus (WNV) are back in the news again.
Last year, you may recall, was a banner year for arboviral disease in the United States (see MMWR: Arboviral Disease Surveillance – 2010) with more than 1,000 cases of West Nile Virus reported.
Other viral players included California serogroup viruses (CALV), eastern equine encephalitis virus (EEEV), St. Louis encephalitis virus (SLEV) and Powassan virus (POWV).
As for Dengue fever - Florida recorded a total of 63 locally-acquired cases, and an epidemic in Puerto Rico produced more than 20,000 cases and 31 deaths.
While we aren’t seeing those kinds of numbers this year, the rains have recently returned to Florida and other parts of the southland, and so the number of mosquito borne illnesses has begun to rise.
A few reports:
Our first stop is Martin County, on the lower S.E. coast of Florida, where a case of imported Dengue fever may have led to a locally acquired infection.
This is from an announcement by the Martin County Health Department.
MARTIN COUNTY HEALTH DEPARTMENT ISSUES HEALTH ADVISORY REGARDING MOSQUITO-BORNE DISEASE
August 9th, 2011
The Martin County Health Department is urging residents to take precautions against mosquito borne illness following a confirmed case of dengue fever. The illness was acquired by a resident of the Rocky Point section of Port Salerno following a recent trip to a Caribbean island. The Health Department is also awaiting test results on a possible second case of the illness in the same household.
As of August 6th, Florida’s Arbovirus Surveillance System has reported 10 cases of imported Dengue fever from travelers returning from countries where that virus is endemic. Additionally, 51 cases of imported Malaria have been reported in Florida as well.
Similarly, Marion County Florida released a statement yesterday regarding an imported case of Dengue, saying:
This is Marion County’s first case of dengue fever this year. The case of dengue fever was contracted
outside of the U.S., but because dengue fever can be transmitted to another human from a mosquito that has bitten a person with the disease, citizens should take every precaution to protect themselves from mosquito bites
Next stop is Duval County (Jacksonville) Florida, where over the past two weeks at least 8 cases of West Nile Virus have been reported. This from the Duval County Health Department.
DCHD MOSQUITO-BORNE ILLNESS ALERT
The Duval County Health Department (DCHD) continues its mosquito-borne illness alert for Duval County. Additional human cases of West Nile Virus (WNV) have been confirmed. The most recent cases involve a 38 year-old male and 57 and 38 year-old females. Duval County has eight confirmed cases of WNV in 2011.
Lest anyone think that mosquito borne illnesses are only a Florida problem, yesterday Mississippi reported their first WNV fatality of the year, and their 13th known infection (AP article State reports first West Nile virus death of year).
Additionally, human infections with WNV have been reported this year in New Jersey, Virginia, California, Arizona, Texas, Colorado, Louisiana, Georgia, North Dakota, South Dakota, and Wyoming.
As the MMWR report on West Nile last week stated:
Detection and reporting are incomplete, leading to a substantial underestimate of the actual number of cases. Based on previous studies, for every case of WNV neuroinvasive disease, approximately 140 human WNV infections occur, with 80% of infected persons remaining asymptomatic and 20% developing nonneuroinvasive disease
The USGS maintains series of interactive disease maps showing the confirmed vector-borne illness reports around the country, along with reports of mosquito, bird, sentinel, and veterinary surveillance.
Reports, as you might expect, can often lag a few weeks behind the current situation. Laboratory tests take time, and there are sometimes other delays in reporting.
With the summer rise in mosquito populations, public health departments are urging people to become more diligent about removing breeding places for mosquitoes around their homes.
But it isn’t just outside the home where people need to check . . . some mosquito species are perfectly capable of setting up light housekeeping inside the home as well.
While the Aedes aegypti is most commonly associated with spreading disease, the Aedes albopictus or `Asian tiger’ mosquito is quite capable of doing so as well.
Aedes Albopictus Photo Credit CDC PHIL
The Asian Tiger mosquito has made extensive inroads around the world over the past 40 years, and is considered one of the top 100 worst invasive species according to the Global Invasive Species Database.
And unlike its aegypti cousin, the albopictus is also a daytime biter, and can often be found inside the home breeding in flower vases, potted plants, toilets, and neglected swimming pools.
Dark Blue indicates the A. Albopictus native range, while green indicates new introductions in last 40 years.
Although mosquitoes are pretty much ubiquitous here in Florida, as well as in and many other areas, one shouldn’t panic over being bitten.
The vast majority of mosquitoes here in the US are not carrying infectious diseases.
The odds of contracting West Nile Virus, Dengue, EEE, or any of the mosquito borne encephalitis viruses are actually pretty small.
In order to vector a disease, they first must bite a host(bird, animal, or human) that is viremic – infected and with sufficient viral material in their bloodstream.
Still, it only makes sense to take precautions.
Like wearing DEET when you are outdoors, wearing long sleeves and pants, and removing breeding places inside and outside of your home.
Any container of water . . . even as small as a bottle cap . . . can breed mosquitoes. Containers with houseplants appear to be particularly good homes for these pests.
For more details on mosquito precautions visit the Florida DOH Mosquito-borne Disease Prevention webpage or the CDC’s FIGHT THE BITE page.
