Florida Arboviral Encephalitis and West Nile (WN) Virus Information

Physicians are Encouraged to Test for and Required to Report Mosquito-Borne Diseases

Historically, Florida has suffered from repeated large epidemics of serious mosquito-borne diseases. In the 1870s and 1880s, outbreaks of yellow fever caused considerable mortality. In 1889, a physician and noted yellow fever expert was selected as the first head of the newly created State Board of Health in large part to control this disease. Large numbers of endemic dengue and malaria cases continued through the early part of the 1900s. Today, two diseases from endemic arboviruses remain: St. Louis encephalitis (SLE) with outbreaks occurring every seven to 10 years; and eastern equine encephalitis (EEE) with a range of 0 to five cases reported each year. In the nearby Caribbean and Central America, other mosquito-transmitted diseases are common (e.g., dengue and malaria). West Nile (WN) virus was first identified in Florida in July, 2001.

Health care providers and laboratories are required to report all suspect or confirmed cases of arbovirus encephalitis and malaria to their county health departments. Identification of human cases of mosquito-borne disease may lead to the issuance of health alerts and/or mosquito abatement activities.

As a service to health care providers, the DOH Laboratory offers arbovirus (e.g., SLE, EEE, dengue and WN) and malaria testing for patients with clinical manifestations. When possible, CSF and sera should be tested simultaneously. Acute sera will be tested for selective arboviral antibodies using HAI, and seropositive samples retested using ELISA IgM. An additional serum sample drawn 3-4 weeks later may be required for confirmation. A laboratory submission form must accompany specimens. For additional information, please contact the DOH Tampa Branch Laboratory at (813) 974-5990 or the DOH Jacksonville Central Laboratory at (904) 791-1540 for arbovirus testing, (904) 791-1602 for malaria testing.

Test

Special Preparation
and Container

Result Indicator

Arbovirus Isolation

Contact Tampa Branch Laboratory for Instructions

Contact Tampa Branch Laboratory for Instructions

See individual report

EEE,SLE, dengue, WN

CSF

CSF frozen, or with cold pack. Test available at Jacksonville & Tampa Branch Laboratories

Positive or Negative

EEE, SLE, dengue, WN (total antibodies)

(HAI and ELISA IgM for acute serum. Convalescent serum sample may be required.)

Red top or serum separation tube. Test available at Jacksonville & Tampa Branch Laboratories

Titer and Interpretation or no antibody detected

Western equine encephalitis, Venezuelan equine encephalitis, La Crosse, Yellow Fever (total antibodies)

Single or paired sera. Travel and exposure history must be submitted with specimen.

Red top or serum separation tube Jacksonville Laboratory only

Titer and interpretation or no antibody detected

Arboviral encephalitis: Arboviral infection from eastern equine encephalitis virus, St. Louis encephalitis virus, Western equine encephalitis virus or West Nile virus may result in febrile illness of variable severity associated with neurologic symptoms ranging from headache to aseptic meningitis or encephalitis. Symptoms include headache, confusion or other alteration in sonsorium, nausea and vomiting. Signs may include fever, meningismus, cranial nerve palsies, paresis or paralysis, sensory deficits, altered reflexes, convulsions, abnormal movements and coma of varying degree.

Dengue Fever: An acute febrile illness characterized by frontal headache, retro-ocular pain, muscle and joint pain, and rash. The principal vector is the Aedes aegypti mosquito and transmission usually occurs in tropical or subtropical areas. Severe manifestations (e.g., dengue hemorrhagic fever and dengue shock syndrome) are rare but may be fatal.

To access the required reporting forms, click this link to go to the page:  How Do I Report?