Dengue fever and dengue hemorrhagic fever (DHF)
are acute febrile diseases, having sudden onset, found in the tropics,
and caused by Flavivirus. It is also known as breakbone fever or dandy
fever. Dengue is transmitted to humans by the Aedes aegypti or more
rarely the Aedes albopictus mosquito, which feed during the day.
The WHO says some 2.5 billion people, two fifths of the world's population, are now at risk from dengue and estimates that there may be 50 million cases of dengue infection worldwide every year. The disease is now epidemic in more than 100 countries. Dengue strikes people with low levels of immunity.
Dengue hemorrhagic fever is a more severe form of the viral illness. This form of dengue fever can be life-threatening or even fatal.
The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can inflict the disease.
The virus is not contagious and cannot be spread directly from person to person. The pathway must be a person-to-mosquito-to-another-person.
Incubation period is around between 3 to 15 days.
Signs and symptoms:
Symptoms start with sudden onset of chill and high rise in temperature around 103-104ºF. The fever last for around 2 to 4 days. Severe headache, muscle and joint pains are associated. There may also be gastritis with some combination of associated loss of appetite, abdominal pain, nausea, vomiting, or diarrhea. The eyes become reddened. A flushing or pale pink rash comes over the face and then disappears. The glands (lymph nodes) in the neck and groin are often swollen.
After rise in temperature for 2 to 4 days, there is drop in temperature with profuse sweating. This precedes a period with normal temperature and a sense of well-being that lasts about a day. A second rapid rise in temperature follows. A characteristic rash appears along with the fever. The dengue rash is characteristically bright red petechiae and usually appears first on the lower limbs and the chest; in some patients, it spreads to cover most of the body. The palms and soles may be bright red and swollen.
Dengue hemorrhagic fever is mostly found in children less than 10 years of age. It starts with continuous fever, sore throat, cough, nausea, vomiting followed by collapsing state of patient. There is cool and clammy extremities, weak pulse and cyanosis. There is bleeding with easy bruising, blood spots in the skin (petechiae), spitting up blood (hematemesis), blood in the stool (melena), bleeding gums, and nosebleeds (epistaxis). Pneumonia is common, and inflammation of the heart (myocarditis) may be present.
Investigation and Diagnosis: