What is Dengue fever?

Dengue fever (pronounced Den-gay) is a viral infection caused by the female mosquito (Aedes aegypti and Aedes albopictus). Dengue fever occurs in tropical and sub-tropical regions and usually increases in the hot and humid months. Dengue fever is not a new disease. It was discovered several hundred years ago. In recent years, dengue fever has become a major international public health concern.

Dengue fever nicknamed "breakbone fever" because dengue patients usually express contorted movements due to intense joint and muscle pain. Benjamin Rush from Philadelphia, US, first described "breakbone fever" in 1780. Slaves who developed dengue fever in the West Indies were said to have "dandy fever" because of their posture and gait.

Dengue fever lasts for approximately 7 days, despite its sudden and acute onset. However, extra precautions should be taken after the recovery period. These precautions will help prevent severe illness from occurring in some people, such as dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS). These illnesses are potentially lethal and are today the leading cause of childhood mortality in several Asian countries.

How is Dengue Fever spread?

Dengue fever is spread through the bite of the Aedes mosquitoes. It is not spread from one person to another.

The transmission cycle for dengue starts when:

• Infected Aedes mosquito bites a healthy person.

• 4-7 days later, the infected person develops fever (after the virus multiplies i.e., incubation period). The person usually then sees a doctor.

• When fever starts, the person becomes infectious for about 5 days.

• If an Aedes mosquito bites the person during this period when he is infectious, it will pick up the dengue virus in his blood.

• The virus takes 7-10 days to multiply in the second mosquito.

• The mosquito then becomes infective and the cycle starts again when it bites another person.

An infected person does not spread the virus to another person directly but he becomes a source of dengue virus for the Aedes mosquitoes.

Where does the Aedes Mosquito breed?

A puddle of water about the size and depth of 20-cent coin is sufficient for an Aedes mosquito to breed in. The Aedes mosquitoes are commonly found breeding in clear stagnant water in flower vases, flower pot plates, roof gutters, earthen jars for water storage or decorative purposes, watering cans, and bamboo pole holders. The Aedes mosquito can also breed in unusual places such as water trapped in the hardened soil in potted plates, and the rim of unwanted pails.