Mosquitoes, Malaria And Dengue

Mosquitoes live in most regions of the world. They are born into water, and it does not have to be much, where they spend around two weeks going through the stages of egg, larva and pupa. As an adult, they live for up to another eight weeks.

The mouth parts of mosquitoes have evolved to be specialized in piercing 'skin' and drawing out juices. Males use this aptitude for removing juices from plants, but females require a blood meal to be able to lay eggs and of the 3,500 species of mosquito worldwide, some species feed on humans.

This characteristic means that the female mosquito of certain species can become the carrier of several infectious diseases. These diseases have an impact on and kill millions of people every year. Two of these diseases are malaria and dengue fever

Malaria is brought about by a mosquito infected with eukaryotic protists of the genus Plasmodium biting humans (and one sortnd of monkey). The disease is widespread throughout Africa, the Americas and Asia but it was eradicated from Australia in 1981. Europe used to be infected too but is now largely clean of malaria, although not of mosquitoes.

The disease is brought about by the duplication of the malarial parasites in the red blood cells which creates indications similar to headaches and fever - something like a severe case of the flu. In acute cases, this can lead to coma and death.

Prevention is far better than cure, so the first thing to do is endeavor to prevent mosquitoes breeding by getting rid unnecessary amounts of water no matter how small and how brackish. Secondly, attempt to prevent them biting you by using mosquito repellent and mosquito nets treated with pesticide.

There is no long-lasting vaccine that will stop you getting malaria, although there are drugs obtainable to prevent travellers getting malaria in the short time. Most types of malaria can be treated successfully, although there is evidence of resistance to several of the anti-malarial drugs.

Dengue Fever is also spread by particular mosquitoes. The symptoms of dengue vary but they almost always include a headache and a skin rash and occasionally joint pain. The disease is not often fatal, but it can be so if it develops into dengue haemorrhagic fever or dengue shock syndrome (where blood pressure falls very low causing organs to malfunction).

There are four kinds of dengue fever. Having had the one, the patient has lifelong immunity to that strain, but only temporary immunity from the other three. As with malaria there is no vaccine against dengue. The only attack is to minimize the number of mosquitoes and the number of bites.

Whereas the incidence of infection by malaria is falling, the incidence of infection by dengue is rising. Dengue is now endemic in over 110 countries. It usually takes 4-7 days for the disease to show itself after infection, so any flu-like indications showing within a week of returning from an area known to have dengue should be treated gravely, particularly as many GP's in the west may overlook the real source of the problem.