The name malaria is derived from two
latin words mal; aria meaning “bad air”. This is due to the mistaken belief
that it was caused by bad air following the observation that it occurred more
frequently around damp places and marshy areas. Almost all races of human
beings have at one time or another suffered from malaria (Bruce-chatt1983).
Malaria is one of the most serious health problems facing the world today.
Malaria is caused by infection with a microscopic parasite
and is transmitted
to humans by the bite of certain sorts of mosquito called anophelines (WHO
1998). Of all the human parasitic infections, malaria caused by four (4)
species of parasitic protozoa belonging to the genus plasmodium ( P); debilitates and kills more people than any
other single infection disease.The four species of plasmodium are: 
Plasmodium falciparum,
P. ovale, P. vivax and P. malaria, have their respective morphology, biological and clinical
characteristics. The P. ovale, P. vivax and
P. malaria are classified as relapsing
malaria because they have a secondary or persisting stage of their life cycle
(Perin et al 1984).
Life cycle of malaria parasite consists
of sexual cycle that takes place in the mosquito and an asexual cycle that
occurs in the vertebrate host. Life inside the mosquito is a race against time,
because the time taken for the parasite to go through its growths and
development is close to the average life span of the insect.
This period is
longer in cooler environment and shortens as the temperatures rises. It is for
this reason that malaria is such a threat to health in the tropics and one of
the many threats posed by global warming could extend the territory in which
malaria is a health problem (WHO 1998). Every year, between 300 and 500 million
people suffer clinical malaria, 1.5-2.7 millions die. Malaria is indigenous
when natural to an area and imported when acquired outside specific area.
Infections deliberately produced for the purpose of research or caused accidentally
(by blood transfusion or other routes) are known as induced malaria (Wilcox,
and Manson-Bahr 1983).
Malaria is still the most important parasitic disease in
the tropics. It causes greater economic lose than any other disease in areas of
high transmission such as the wet savanna areas of tropical African, Children
under the age of 8 and women in their first pregnancy are most vulnerable to
the disease. The effects of malaria are noticeable in rural areas where malaria
frequently strikes during that period of the year when the need for
agricultural work is greatest (WHO, 2000).
In many of these areas, the health
infrastructure is not sufficiently developed to ensure that an evolving
favorable epidemiological situation is maintained. Studies in rural areas of Africa where malaria is endemic revealed that over one
third of primary school children had malaria during a school term, more than
half of this group had two or more attacks typically missing a week or more of school
with each attach(WHO, 1996). At a rural clinic in tropical Africa, it would not
be unusual to find each of the following patients waiting for attention; A man
complaining of feverishness for the past two days but he is still able to work,
but requires for treatment to make him feel better; A child whose mother is
worried because the boy looks dull and seems less energetic than usual; A young
girl who is hot, deeply unconscious and having repeated convulsions of the
whole body, each of these patients is suffering from malaria.
For the first, its simply a nuisance;
for the second, profound anemia has developed, which could be fatal if
untreated, for the third the function of the brain has been affected and the
child is in danger of losing her life. The illnesses in the second and third of
these individuals are referred to as different forms of severe malaria. Thus
malaria parasites cause different kinds of illness in different people.
The
contributing reasons are because; the species of malaria parasite is important
only P. falciparum causes severe
disease in some people knowing that there are differences even between strains
of P.falciparum in their capacity to
cause disease; the immunity of the individual also affects how ill a person
becomes when infected with malaria. The first patient described above was
probably protected by immunity acquired slowly over years of repeated
infection. It is also found that some people are genetically less susceptible
than others to severe illness when infected with P. falciparum. Once severe malaria develops, extra facilities are
usually needed to give the patient adequate treatment but in rural areas of Africa health infrastructures and facilities is not
sufficiently developed which may lead to lose of life or disabilities (WHO,
1998).
Clinical courses of malaria consist of
bouts of fever accompanied by other symptoms and alternating with periods of
freedom from any feeling of illness (Goettel, 1982). The life cycle of the
parasites consists of an extrinsic phase in the invertebrate host of the
anopheles mosquito and intrinsic phase in man that is divided into two; the
erythrocytic schizogony in the liver cells and the erythrocytic schizogony in
the red blood cells (Bahar, 1984). The female anopheline mosquito has been
recognized as the vector of malaria.
The anopheles belongs to the order of
diptera, family culicidae and tribe anopheline. About 400 species of anopheles
exist throughout the world, but only some 60 species are important vectors of
malaria under natural conditions (Coluzzi, 1984). Development of the parasite
that is contained in the saliva of the mosquito begins if a female anopheline
mosquito bites an infected person, it injects the sporozites into the blood stream of the human host and
sucks the microgametocytes and macrogametocystes into its gut. These
gametocytes develop into gametes in the gut of the mosquito. The
microgametocytes mature by exglagellation and macrogametocyte develop into
macrogametes with nuclei shifted to the periphery where projections are formed.
Fertilization occurs when a microgamete
penetrates the projections and a zygote is formed. Zygote gives rise to
ookinete. After a period of 4-15 days after ingestion of gametocytes by
mosquito, the oocyst mature with multiplication of nuclei and transformation of
sporozoites depending on the temperature (Bukot, 1987).
Incubation period is the time between
the infection and the first appearance of clinical signs of which fever is the
most common (Sherman,
1998). The incubation period is usually between 9-30 days and varies with the
species of the parasites (Shortest for P.
falciparum longest for P. malariae
) this also depends on the circumstances of the infection, whether natural, by
mosquito bite or artificial e.g by injection infected blood (WHO, 1983).
In the course of study, two or more
parasites can be found in the human host blood and there is a tendency for one
species of the parasites to predominate over the others. This is known as mixed
infection. The most common types of mixed infection are P. falciparum and P. vivax
in sub tropical areas while in tropical Africa
P. falciparum and P. malaria are prevalent. Cerebral
malaria is observed as caused by mixed infection (Lyn, 1987).
The modes of transmission of the disease
include blood transfusion which does not involve the pre-erythrocytic and
exo-erythrocytic stages. Malaria transmitted in this way is easily cured and
does not involve relapses. Another process is by congenital transmission that
is seen in pregnant mother to their child. The major mode of transmission is
through the vector.
The growth rate of the larva of mosquito
determining transmission rate is directly proportional to the suitability of
the environment to its requirement that vary from species to species (Thompson,
1996). In tropical Africa, the climatic
condition favour an intense transmission of P.
falciparum the prevailing parasite through mosquito vector of which the
notorious and ubiquitous A. gambiae is
the most important because of its wide distribution, breeding habits, large members
and preference for human blood (Bruce, 1983).
The epidemiological data reveal that
malaria induced morbidity and mortality may vary considerably within a
relatively small area (Olaleye, 1995). A prevalence of 90 % has been reported
for wet season in Ebonyi
State (Eneanya, 1998).
The management of malaria by people
dates back to the origin of malaria. In modern times managing malaria could
mean treating the infection using antimalaria drugs, but the malarias parasite
has proved a formidable adversary for medical researchers. Invariable it owes
its success to the fact that it has chosen not to live as a free living
organism but a parasite and has adapted to the host and its immune system
(Nowikowski, 1987). Beside, vector resistance to insecticides, other factors
that could possible influence malaria situation in a community include the
development of resistance in P.
falciparum to drugs (Nguyeh et al.,
1982).
Resistance of P. falciparum to
drugs has become the most important threat to effective control of the disease.
In Nigeria,
there is paucity of information on studies on the malaria management of the
poor. However various antimalarias abound, both local and scientific
preparations are used by people. The introduction of insecticide treated nets
(ITN) and the possibility of using vaccines helps a lot (Hira, 1987). The cost
of treating malaria illness accounts for one-third cost of the illness,
two-third reflect the time (Bonilla et
al, 1992).
RELATED INFORMATION