Dengue Hemorrhagic Fever - The Critical Phase of Dengue Fever

By A. K. Nath

Dengue is an infectious tropical disease caused by the dengue virus. It is transmitted by several species of mosquitoes with aedes aegypti being the primary vector. Symptoms of dengue include fever, headache and muscle and joint pains. In some cases, a characteristic measles-like rash is also observed. In a small proportion of the cases, dengue develops into dengue haemorrhagic fever which is characterized by bleeding, low platelet count and blood plasma leakage. A more severe stage is dengue shock syndrome where dangerously low blood pressure is observed.

The majority of people infected with dengue virus do not show symptoms or show mild symptoms. Severe illness is observed only in 5% of the cases. Dengue is life-threatening in a small proportion of cases. Incubation period ranges from 3 to 14 days. The course of infection is in three phases: febrile, critical and recovery. High fever is observed in the febrile phase. Pain and headache are also experienced. This phase lasts for 2-7 days. A measles-like rash is also observed in 50-80% of the cases.

In the critical phase, dengue proceeds to a severe phase as the fever resolves. During this phase, plasma leaks from the blood vessels, resulting in accumulation of fluid in the chest and abdominal cavity. There may also be depletion of fluid from the circulatory system and reduced blood supply to vital organs of the body. This condition is known as dengue haemorrhagic fever. It can be life-threatening and occurs in about 5% of all cases. People previously infected with other dengue serotypes are at increased risk of developing haemorrhagic fever. Children and young adults are also are at higher risk of developing this condition.

The recovery phase occurs next. The leaked fluids are absorbed back into the bloodstream. This generally lasts 2-3 days. In some cases, another rash followed by peeling of skin may be observed. Fatigue may last for weeks. A fluid overload state may also occur in some cases.

There are no antiviral drugs for dengue. Paracetamol is prescribed for fever. Blood transfusion may be prescribed if the haematocrit value becomes too low. Treatment is aimed at maintaining fluid balance in the body and managing the associated symptoms. People who are able to drink and pass urine can be managed at home using rehydration therapy. However, if the symptoms are severe, the patient will have to be cared for in the hospital. Patients with dengue haemorrhagic fever have to be cared for an intensive care unit.

For more information on dengue, visit http://www.dengue-info.com.

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