 |
Dengue
Fever Dengue fever may begin suddenly. There are estimated 50-100 million cases of Dengue fever/year. 250-500,000 cases of Dengue hemorrhagic fever worldwide. Most deaths are in children 5-15 years. Risk
to travelers is estimated 1/1,000 in countries where it is present
but could be worse in outbreaks. Dengue
transmission by mosquito:
Adults lay eggs as floating egg rafts in puddles. These mosquitoes
thrive on small puddles. One single mosquito will feed many times so that many people could become infected at the same time. These mosquitoes are found active in the daytime and are found in and around human habitation. They lay eggs in shallow containers that rainwater has collected in. Recently the mosquito Ades albopictus has been recognized as a disease causing mosquito. Aedes Albopictus (Asian Tiger mosquitoes) were recently introduced to Hawaii and Texas. If the dengue virus is also introduced into these areas as well then dengue transmission could occur. This
mosquito also causes Eastern Equine Encephalitis and Cack Valley
viruses, but not Yellow Fever. Dengue
infection: Nausea, vomiting and anorexia may also occur.
A rash may also appear 3-4 days after the onset of fever spreading
from the torso to the arms, legs and face. Patients should be checked for evidence of bleeding, their hydration status, and their blood pressure. Bleeding
is evidenced by petechiae, purpura, increased bleeding from gums
and increased menstrual flow. Co-factors that will worsen the severity of dengue include having a prior infection with one or more of the other 3 serotypes (and how long ago, and how severe); age; and host genetics. The strain of serotype is also important with the lethality ranked: DEN 2>3>4>1. Unusual
complications of dengue are encephalopathy, liver and heart damage;
and gastrointestinal bleeds. Blood serology should be taken during the acute phase (less than 5 days after start of fever) to check for acute serology and virus isolation; and again after 6-21 days to check for convalescent serology and confirm the diagnosis. A rapid diagnostic test for dengue fever is at present not approved. If
the fever starts greater than 2 weeks after the end of travelling
then this is not dengue fever, as dengue will present within 2 weeks.
Patients may be treated at home if there is no bleeding and well hydrated. Observation is warranted if sicker and ICU admission if bleeding. Serial hemoglobin and platelets are done until afebrile for 1-2 days. Other treatments include IV fluids and avoidance of invasive procedures. Steroids
and gammaglobulin are unproven treatments. Use DEET 20-30%, spray clothing with permethrin, and spray insecticide over bed. Wear long sleeved pants and shirts. Persons may also decrease risk by spending less time in areas where dengue more frequent. Residential areas are the most affected while industrialized or commercial areas (like beaches, forests, and tennis courts) have less Aedes mosquitoes. Air
conditioning helps remove mosquitoes. |
|
|
