Monday, October 21, 2013
The four types of parasites responsible for
malaria infection in man are Plasmodium falciparum, Plasmodium vivax, Plasmodium
malariae and Plasmodium ovale. They are transmitted by various species of the
Anopheles mosquito. Plasmodium falciparum species is responsible for most
attacks, deaths and the severest forms of malaria. The clinical features of
malaria are protean. Consequently, in endemic areas, malaria must be considered
in any patient presenting with fever.
Malaria occurs mostly in poor, tropical and subtropical areas of the world.
However, Africa is the most affected continent. According to the World Health
Organization’s World Malaria Report 2011 and the Global Malaria Action Plan, in
2010, malaria caused an estimated 216 million clinical episodes, and 655,000
deaths. Of the deaths, an estimated 91% occurred in the African Region compared
to only 6% in the South-East Asian Region, and 3% in the Eastern Mediterranean
Region (3%). About 86% of deaths globally were in children.
Africa is the worst affected region due to a
combination of several factors. These include:
The most vulnerable populations are persons with
no or little immunity against the disease. These include young children who have
not yet developed partial immunity to malaria; pregnant women whose immunity is
decreased by pregnancy, especially during the first and second pregnancies; and
travelers or migrants coming from areas with little or no malaria transmission,
who lack immunity.
After incubation in the liver the malaria
parasite invades red blood cells causing them to be sticky to and to break up –
a process that is referred to as haemolysis. Stickiness of cells leads to
mechanical blockage of capillaries and local inflammation while the haemolysis
leads to anaemia. Other effects of malaria include fever, anorexia, reduced food
intake, vomiting, diarrhea, increased metabolic needs and coma. Without
treatment malaria can be rapidly fatal. Repeated attacks of malaria cause a
negative nitrogen balance, poor cognition, acute malnutrition or worsened states
of malnutrition. In pregnancy malaria causes anaemia, abortion, premature
delivery and low-birth babies and all of their attendant complications.
Malaria is both preventable and curable.
Increased malaria prevention and control measures are dramatically reducing the
malaria burden in many places. Non-immune travellers from malaria-free areas are
very vulnerable to the disease when they get infected. Prevention is best
effected by the use of mosquito nets that are impregnated with long-lasting
insecticides. Although studies are promising, there is currently no effective
vaccine against malaria. Cure can be achieved by using combination anti-malaria
Cerebral malaria, one of the severe complications
of falciparum malaria, affects predominantly children between the ages of 1 and
3 years. Curiously cerebral malaria is more commonly seen in well-nourished than
in malnourished children; and some reports have suggested that malnutrition may
be protective of severe forms of malaria.
The interrelation between malaria and
malnutrition is not clearly understood. The hypothesis that severe malnutrition
is protective of malaria is based on several arguments: a) malaria parasites in
the blood are known to increase after a re-feeding; b) the findings of autopsy
studies; and c) studies on trace elements and C - reactive protein in malaria.
However, in a very detailed review article, Shanka has pointed out those studies
claiming that severe malnutrition is protective of malaria lack power to support
In summary, the duo of malaria and undernutrition
acting independently, are major causes of morbidity and mortality in the
developing countries of the world and particularly in Africa. However, the
interrelationship between malaria and malnutrition is not well understood and
remains an area needing further elucidation.
James Kweku Renner and Gabriel
Nestle Nutrition Institute Africa