MALARIA FEVER

What is malaria disease

Malaria is a potentially deadly tropical disease characterized by cyclical bouts of fever with muscle stiffness, shaking and sweating. It is caused by a tiny parasite (genus Plasmodium) that is transmitted by the female mosquito (genus Anopheles) when it feeds on blood for its developing eggs.
Severe malaria is not readily distinguishable from other severe diseases, such as pneumonia typhoid and meningitis that require very different therapy.
Almost all vertebrates, birds, snakes and monkeys, for example, can be infected by Plasmodium (malaria) parasites. Different animal species can only be infected by their own specific species of Plasmodium.
Humans are generally host to four species of malaria parasites: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. Plasmodium falciparum causes the most dangerous complications, such as cerebral malaria. It is the species that is most virulent and potentially lethal to humans.
Because of its dependence on human/vector (mosquito) contact, malaria is considered to be a disease of poverty. Poor people can be physically marginalized and live closer to degraded land and conditions where mosquitoes thrive. They are also less likely to have physical barriers such as screens or nets to protect them and they often lack the education and resources to access proper care and treatment.
Intense and costly control programmes targeting malaria, that incorporate a variety of approaches such as environmental modification and indoor spraying with DDT, have succeeded in eliminating or significantly reducing the disease in many countries. Malaria has been eliminated in former Soviet Republics, the USA, Italy, Korea and many Caribbean Islands.
The Anopheles gambiae mosquito selects small, sunlit collections of water to lay its eggs. The intact forest provides few such breeding sites so there are few malarious mosquitoes in dark jungles and tropical forests. Replacing tropical forests with agricultural land provides the mosquitoes with the conditions and proximity to human hosts that they require to thrive.
Malaria is transmitted by an infected, female mosquito; Anopheles gambiae. It can also be acquired from an infected blood transfusion or even from the shared needles of drug addicts.
Human malaria parasites only develop in Anopheles mosquitoes. The parasites move to the salivary glands of the mosquito and are injected into a human host by the feeding insect.

Cause

Human malaria is caused by four different species of the protozoan parasite
Plasmodium: Plasmodium falciparum, P. vivax, P. ovale and P. malariae.

Transmission

The malaria parasite is transmitted by various species of Anopheles mosquitoes,
which bite mainly between sunset and sunrise


Nature of the disease
Malaria is an acute febrile illness with an incubation period of 7 days or longer.
Thus, a febrile illness developing less than one week after the first possible
exposure is not malaria.
The most severe form is caused by P. falciparum, in which variable clinical features
include fever, chills, headache, muscular aching and weakness, vomiting, cough,
diarrhoea and abdominal pain; other symptoms related to organ failure may
supervene, such as: acute renal failure, generalized convulsions, circulatory
collapse, followed by coma and death. In endemic areas it is estimated that about 1% of patients with P. falciparum infection die of the disease; the mortality in
non-immune travellers with untreated falciparum infection is significantly higher.
The initial symptoms, which may be mild, may not be easy to recognize as being
due to malaria. It is important that the possibility of falciparum malaria is
considered in all cases of unexplained fever starting at any time between the
seventh day of first possible exposure to malaria and three months (or, rarely,
later) after the last possible exposure. Any individual who experiences a fever in
this interval should immediately seek diagnosis and effective treatment, and
inform medical personnel of the possible exposure to malaria infection.
Early diagnosis and appropriate treatment can be life-saving. Falciparum malaria
may be fatal if treatment is delayed beyond 24 hours. A blood sample should be
examined for malaria parasites. If no parasites are found in the first blood film
while there is clinical suspicion of malaria, a series of blood samples should be
taken at 6–12-hour intervals and examined very carefully.
Pregnant women, young children and elderly travellers are particularly at risk.
Malaria in pregnant travellers increases the risk of maternal death, miscarriage,
stillbirth and neonatal death.
The forms of malaria caused by other Plasmodium species are less severe and
rarely life-threatening.
Chemoprophylaxis and treatment of falciparum malaria are becoming more
difficult because  P. falciparum is increasingly resistant to various antimalarial
drugs. Chloroquine resistance of P. vivax is rare and was first reported in the
late 1980s in Papua New Guinea and Indonesia. Focal “true” chloroquine
resistance (i.e. in patients with adequate blood levels at day of failure) or
prophylactic and/or treatment failure have later also been observed in Brazil,
Columbia, Ethiopia, Guatemala, Guyana, India, Myanmar, Peru, the Republic
of Korea, Solomon Islands, Thailand and Turkey.  P. malariae  resistant to
chloroquine has been reported from Indonesia.

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