DISEASES CAUSED BY MOSQUITO BITE

DENGUE FEVER

Dengue fever, also known as breakbone fever, is a mosquito-borne tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. In a small proportion of cases, the disease develops into the life-threatening dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs.

Dengue is transmitted by several species of mosquito within the genus Aedes, principally A. aegypti. The virus has five different types;[1] infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different type increases the risk of severe complications. As there is no commercially available vaccine, prevention is sought by reducing the habitat and the number of mosquitoes and limiting exposure to bites.

Treatment of acute dengue is supportive, using either oral or intravenous rehydration for mild or moderate disease, and intravenous fluids and blood transfusion for more severe cases. The number of cases of dengue fever has increased dramatically since the 1960s, with between 50 and 528 million people infected yearly. Early descriptions of the condition date from 1779, and its viral cause and transmission were understood by the early 20th century. Dengue has become a global problem since the Second World War and is endemic in more than 110 countries. Apart from eliminating the mosquitoes, work is ongoing on a dengue vaccine, as well as medication targeted directly at the virus.

MALARIA

Malaria is a mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans (a group of single-celled microorganisms) belonging to the genus Plasmodium. Malaria causes symptoms that typically include fever, fatigue, vomiting, and headaches. In severe cases it can cause yellow skin, seizures, coma, or death.[2] The disease is transmitted by the biting of mosquitos, and the symptoms usually begin ten to fifteen days after being bitten. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria.

The disease is most commonly transmitted by an infected female Anopheles mosquito. The mosquito bite introduces the parasites from the mosquito’s saliva into a person’s blood. The parasites travel to the liver where they mature and reproduce. Five species of Plasmodium can infect and be spread by humans.Most deaths are caused by P. falciparum because P. vivax, P. ovale, and P. malariae generally cause a milder form of malaria. The species P. knowlesi rarely causes disease in humans. Malaria is typically diagnosed by the microscopic examination of blood using blood films, or with antigen-based rapid diagnostic tests. Methods that use the polymerase chain reaction to detect the parasite’s DNA have been developed, but are not widely used in areas where malaria is common due to their cost and complexity.

The risk of disease can be reduced by preventing mosquito bites by using mosquito nets and insect repellents, or with mosquito-control measures such as spraying insecticides and draining standing water. Several medications are available to prevent malaria in travellers to areas where the disease is common. Occasional doses of the medication sulfadoxine/pyrimethamine are recommended in infants and after the first trimester of pregnancy in areas with high rates of malaria. Despite a need, no effective vaccine exists, although efforts to develop one are ongoing. The recommended treatment for malaria is a combination of antimalarial medications that includes an artemisinin. The second medication may be either mefloquine, lumefantrine, or sulfadoxine/pyrimethamine. Quinine along with doxycycline may be used if an artemisinin is not available. It is recommended that in areas where the disease is common, malaria is confirmed if possible before treatment is started due to concerns of increasing drug resistance. Resistance among the parasites has developed to several antimalarial medications; for example, chloroquine-resistant P. falciparum has spread to most malarial areas, and resistance to artemisinin has become a problem in some parts of Southeast Asia.

The disease is widespread in the tropical and subtropical regions that exist in a broad band around the equator. This includes much of Sub-Saharan Africa, Asia, and Latin America. Malaria is commonly associated with poverty and has a major negative effect on economic development. In Africa, it is estimated to result in losses of US$12 billion a year due to increased healthcare costs, lost ability to work, and negative effects on tourism.The World Health Organization reports there were 198 million cases of malaria worldwide in 2013.This resulted in an estimated 584,000 to 855,000 deaths, the majority (90%) of which occurred in Africa.

CHIKUNGUYA

Chikungunya is an infection caused by the chikungunya virus. The disease features the sudden onset of fever two to four days after exposure. The fever usually lasts two to seven days, while accompanying joint pains typically last weeks or months but sometimes years.The mortality rate is a little less than 1 in 1000, with the elderly or those with underlying chronic medical problems most likely having severe complications.

The virus is passed to humans by two species of mosquito of the genus Aedes: A. albopictus and A. aegypti. Animal reservoirs of the virus include monkeys, birds, cattle, and rodents.This is in contrast to dengue, for which primates are the only hosts.cSince 2004, the disease has occurred in outbreaks in Asia, Europe and the Americas.

The best means of prevention is overall mosquito control and the avoidance of bites by mosquitoes in areas where the disease is common. This may be partly achieved with the use of mosquito nets. No specific treatment is known, but supportive care is recommended, including rest, fluids, and medications to reduce fever and joint pain.

**Article is taken from Wikipedia

**Image from “Mosquito 2007-2” by Alvesgaspar – Own work. Licensed under CC BY-SA 3.0 via Commons – https://commons.wikimedia.org/wiki/File:Mosquito_2007-2.jpg#/media/File:Mosquito_2007-2.jpg