Dengue is on the rise again. There are several reported outbreaks in Metro Manila and in the provinces. This is not new. In fact, in 2005, there were 21,537 cases of dengue in the Philippines. Two hundred eighty of these died. From January to August 2006, there were 13,468 cases with 167 dead. Indeed, just like flooding and political booboos, Dengue has become a mainstay of the colorful Philippine scenario.
Dengue fever and dengue hemorrhagic fever (DHF) are acute febrile diseases caused by one of four closely related virus serotypes of the genus Flavivirus, transmitted to humans by the Aedes aegyptii mosquito, which feeds during the day.
This infectious disease is manifested by a sudden onset of fever, with severe headache, muscle and joint pains ( myalgias and arthralgias - severe pain gives it the name break-bone fever or bone crusher disease) and rashes; the dengue rash is characteristically bright red petechia and usually appears first on the lower limbs and the chest - in some patients, it spreads to cover most of the body. There may also be gastritis with some combination of associated abdominal pain, nausea, vomiting or diarrhea.
Some cases develop much milder symptoms, which can, when no rash is present, be misdiagnosed as influenza ("flu") or other viral infection. Thus, travelers from tropical areas may inadvertently pass on dengue in their home countries, having not been properly diagnosed at the height of their illness. Patients with dengue can only pass on the infection through mosquitoes or blood products while they are still with fever.
The classic dengue fever lasts about six to seven days, with a smaller peak of fever at the trailing end of the fever (the so-called "biphasic pattern"). Clinically, the platelet count will drop until the patient's temperature is normal.
Cases of DHF also show higher fever, hemorrhagic (bleeding) phenomena, thrombocytopenia (decreased platelet count), and haemoconcentration (increased hematocrit). A small proportion of cases lead to dengue shock syndrome (DSS), which has a high mortality rate.
The diagnosis of dengue is usually made clinically. The classic picture is high fever with no localizing source of infection, a petechial rash with thrombocytopenia and relative leukopenia (decreased white blood cells).
There exists a World Health Organization (WHO) definition of Dengue Hemorrhagic fever that has been in use since 1975. All four criteria must be fulfilled:
- Hemorrhagic tendency (positive tourniquet test, spontaneous bruising, bleeding from mucosa, gingiva, injection sites, etc.; vomiting blood, or bloody diarrhea)
- Thrombocytopenia (less than 100,000)
- Evidence of plasma leakage ( hematocrit of more than 20% higher than expected, or drop in haematocrit of 20% or more from baseline following IV fluid, pleural effusion, ascites, hypoproteinemia)
Dengue shock syndrome is defined as dengue hemorrhagic fever plus:
- Weak rapid pulse,
- Narrow pulse pressure (less than 20 mm Hg)
Or,
- Hypotension for age;
- Cold, clammy skin and restlessness.
The mainstay of treatment is supportive therapy. Increased oral fluid intake is recommended to prevent dehydration. Supplementation with intravenous fluids ("Dextrose") may be necessary to prevent dehydration and significant hemoconcentration if the patient is unable to maintain oral intake. A platelet transfusion is indicated in rare cases if the platelet level drops significantly (below 20,000) or if there is significant bleeding.
The presence of melena (black tarry stool) may indicate internal gastrointestinal bleeding requiring platelet and/or red blood cell transfusion.
It is very important to avoid aspirin and non-steroidal anti-inflammatory medications (like mefenamic acid, ibuprofen etc.). These drugs are often used to treat pain and fever, though in this case, they may actually aggravate the bleeding tendency associated with some of these infections. Patients should receive instead acetaminophen preparations (like Biogesic) to deal with these symptoms if dengue is suspected. Having a strong immune system also benefits recovery from dengue.
There is no vaccine for preventing dengue. The best preventive measure for residents living in areas infested with Aedes aegypti is to eliminate the places where the mosquito lays her eggs, primarily artificial containers that hold water.
Items that collect rainwater or are used to store water (for example, plastic containers, drums, buckets, or used automobile tires) should be covered or properly discarded. Pet and animal watering containers and vases with fresh flowers should be emptied and scoured at least once a week. This will eliminate the mosquito eggs and larvae and reduce the number of mosquitoes present in these areas.
For travelers to areas with dengue, as well as people living in areas with dengue, the risk of being bitten by mosquitoes indoors is reduced by utilization of air conditioning or windows and doors that are screened. Proper application of mosquito repellents containing 20% to 30% DEET as the active ingredient on exposed skin and clothing decreases the risk of being bitten by mosquitoes. The risk of dengue infection for international travelers appears to be small, unless an epidemic is in progress.
http://www.cdc.gov/ncidod/dvbid/dengue/dengue-qa.htm
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