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Delaware Health Alert Network #255

August 2, 2011 9:40am

Health Advisory

The Delaware Division of Public Health (DPH) would like to alert the medical community of the increased potential for severe mosquito-transmitted illnesses among travelers to endemic countries or regions. Clinicians should be vigilant for severe mosquito-transmitted illnesses among local travelers returning from the tropics and subtropics.

Dengue is a mandatory reportable disease to Delaware’s Division of Public Health. Report suspected cases to DPH Epidemiology (1-888-295-5156).


DPH is investigating a small cluster of Dengue-like illnesses among 4 of 12 missionary workers from Delaware who recently returned after 10 days in Haiti. Initial testing of these four cases is Dengue-specific for IgM and/or IgG antibodies. Serum samples from 3 of the 4 cases are being sent to the Centers for Disease Control and Prevention (CDC), Dengue Branch, for confirmatory testing.

In this cluster, a clinician identified Dengue-like illness in a pediatric traveler returning from Haiti, submitted specimens for testing to a reference laboratory, and promptly notified DPH. After this case was identified, DPH was able to investigate and identify three additional individuals that sought medical care and were diagnosed as having a Dengue-like illness.


Dengue transmission has been increasing to epidemic levels in many parts of the tropics and subtropics where it had previously been absent or mild. Dengue-affected areas are widely distributed throughout Africa, Asia, Pacific, the Americas and the Caribbean. During 2010, more than 50 countries reported evidence of Dengue transmission; including 17 countries in Asia, 17 in the Americas, 10 in Africa, seven in the Caribbean, and one in the Pacific. As many as 100 million people are infected in the world every year. The mosquitoes known to transmit dengue virus, Aedes aegypti and Aedes albopictus, are present throughout much of the southeastern United States and infected returning travelers may pose a risk for initiating local transmission.


The principal symptoms of Dengue fever are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Generally, younger children and those with their first Dengue infection have a milder illness than older children and adults.

Dengue hemorrhagic fever is characterized by a fever that lasts from 2 to 7 days, with general signs and symptoms consistent with Dengue fever. When fever declines, symptoms including persistent vomiting, severe abdominal pain, and difficulty breathing, may develop. This marks the beginning of a 24- to 48-hour period when the smallest blood vessels (capillaries) become excessively permeable (“leaky”), allowing the fluid component to escape from the blood vessels into the peritoneum (causing ascites) and pleural cavity (leading to pleural effusions). This may lead to failure of the circulatory system and shock, followed by death, if circulatory failure is not corrected. In addition, the patient with Dengue Hemorrhagic Fever (DHF) has a low platelet count and hemorrhagic manifestations, tendency to bruise easily or other types of skin hemorrhages, bleeding nose or gums, and possibly internal bleeding. http://www.cdc.gov/dengue/fAQFacts/index.html

Laboratory Guidance and Diagnostic Testing:

Health care providers seeing a patient who has an illness consistent with Dengue, as described above, and who has recently traveled to Haiti or other endemic regions should seriously consider laboratory testing. Initiation of supportive care should not be delayed pending results of laboratory testing.

Dengue can be diagnosed by isolation of the virus, by serological tests, or by molecular methods. Diagnosis of acute (on-going) or recent Dengue infection can be established by testing serum samples during the first 5 days of symptoms and/or early convalescent phase (more than 5 days of symptoms). Infection with Dengue virus is confirmed when the virus is isolated from serum or autopsy tissue specimens, or the specific Dengue virus genome is identified by reverse transcription-polymerase chain reaction (RT-PCR) from serum or plasma, cerebrospinal fluid, or tissue specimens during an acute febrile illness.

The CDC Dengue Branch provides free diagnostic testing for physicians and confirmatory Dengue testing for health departments and private laboratories. While some commercial laboratories in the US offer diagnostic services for dengue, these commercial labs are not always able to provide results that can distinguish recent from past Dengue infection.

Please contact DPH Epidemiology at 1-888-295-5156 to coordinate confirmatory testing at CDC.

Complete CDC guidance: http://www.cdc.gov/dengue/clinicalLab/laboratory.html


Prompt reporting of suspected cases of dengue or other mosquito-transmitted illnesses to DPH Epidemiology (1-888-295-5156) can facilitate diagnostic testing and initiate the public health investigation.

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