A viral infection with Aedes mosquitoes as its vector. It is carried in the blood by a bite of a female Aedes mosquito and brings catastrophic damages to the human body, or in some cases may be mild and needs only symptomatic treatment.

Dengue also known as Breakbone or Dandy Fever is an acute febrile disease characterized by sudden onset, with headache, fever, prostration, joint and muscle pain, lymphadenopathy, and a rash that appears simultaneously with a second temperature rise following an afebrile period. The disease is endemic in tropics and subtropics.

The causative agent, a Group B arbovirus with 4 distinct serogroups, is transmitted by bites of Aedes mosquitoes.

Following an incubation period of 3 to 15 days, onset is abrupt with chills, or chilly sensation, headache, postorbital pain, in moving the eyeballs, lumbar backache, and prostration. Extreme aching of the legs and joints occurs in the first hours of the illness. The temperature rises to as high as 40 degrees centigrade with relative bradycardia, and hypotension. The bulbar and palpebral conjunctivae are injected, and a transient flushing or pale pink macular rash of the face, usually appear. The spleen may be soft, and enlarged. Cervical, epitrochlear, and inguinal lymph nodes are usually enlarged. Fever and other symptoms may persist for 48 to 96 hours followed by defervescence with profuse sweating. This is described as the afebrile period which may last for 24 hours. A second rapid temperature rise follows usually with a peak lower than the first producing a saddle-back temperature curve. A characteristic maculopapular eruption simultaneously appears, usually spreading from the extremities to the entire body except the face or distributed patchily over the trunk and extremities. The palms and the soles may be bright red and edematous. The fever, rash, and headache and other pains constitute the dengue triad. Cases have occurred without the second febrile period. Mortality is nil, convalescence may be prolonged lasting several weeks and accompanied by asthenia. An attack produces immunity for a year or more.

Serologic diagnosis may be done by HI and CF tests using paired sera but may be complicated by other Group B arbovirus antibodies. Leukopenia is present by the 2^nd day of fever; by the 4^th or 5^th day, the white blood cells have dropped to 2000 to 4000 with only 20 to 40 % granulocytes. Moderate albuminuria and a few casts may be found.

Prevention requires control or eradication of the mosquito vector, to prevent transmission to mosquitoes, and patients should be kept under a mosquito net until the second fever has abated. Treatment is symptomatic with complete bed rest.

Dengue Hemorrhagic Fever Syndrome also known as Southeast Asian Fever is an acute disease occurring in children where dengue is endemic, and characterized by an abrupt fever onset followed by hemorrhagic manifestations, and circulatory collapse. Virtually all patients are under 10 years old.

Onset is abrupt, with fever, nausea and vomiting, abdominal pain, cough, pharyngitis and dyspnea. Shock occurs 2 to 6 days after onset, with sudden collapse or prostration, cool clammy extremities, trunk often warm, weak thready pulse, and circumoral cyanosis. Bleeding tendencies may occur, usually as purpura, petechiae, or ecchymoses at injection sites; sometimes as hematemesis, melena, or epistaxis and occasionally as subarachnoid bleeding or hemorrhage. Myocarditis may be present. Hepatomegaly and bronchopneumonia are common with or without effusions. Mortality rate ranges from 6 to 30%, and most deaths occur in infants below 1 year old. Hemoconcentration is present during shock, with hematocrit above 50%, with the white blood cells elevated in 1/3^rd of the patients. Thrombocytopenia, less than 100,000/cu mm, positive tourniquet test, and prolonged prothrombin time are characteristic findings. Serologically positive for Ig M Ab test. The degree of hemoconcentration, dehydration, and electrolyte imbalance must be evaluated immediately and monitored closely for the first few days since shock may occur and recur precipitously. Plasma or human albumin may be given as well as fresh blood or platelet transfusion to control bleeding. Tranquilizers may help for agitated patients as well as steroids and amines.