Malaria has been known to be the most devastating infectious parasitic disease known to human kind for centuries. An estimate of 438,000 malaria deaths have been reported around the world in 2015 and approximately 69% (306,000) were children less than 5 years of age. Of all malaria deaths that have been reported, 90% were reported from African regions and rests were from South-East Asia region and the Eastern Mediterranean region (Ahiboh et al., 2008).
Malaria poses a great threat to pregnant women and their fetuses. In areas with high transmission of malaria, it has been estimated that at least 25% of pregnant women are infected with malaria, which account for more than 20% of all maternal deaths. Malaria accounts for over 10,000 maternal and 200,000 neonatal deaths per year globally (WHO, 2010).
Malaria infection in pregnant women results into clinical complications, such as anemia, pulmonary edema, hypoglycemia, cerebral malaria, puerperal sepsis, and some time death too.
The Consequences of malaria during pregnancy in fetus are abortion, still birth, intra uterine growth retardation (IUGR), premature delivery, and low birth weight (LBW).
Low Birth Weight of the infant has been suspected to be the cause of poor cognitive and neuro-sensory development of the child (WHO, 2010). WHO recommends that in areas of high malaria transmission, people should be provided with insecticide-treated mosquito nets and intermittent preventive treatment (IPT) with sulphadoxine–pyrimethamine should be given as a part of antenatal care.
Placenta, which is the interface between mother and fetus, plays important role in successful pregnancy outcome and growth of the fetus that is critically dependent on the placenta.
Malaria remains a leading cause of ill health, causing an estimated 243 million cases of clinical malaria and 863,000 deaths (WHO, 2010). More than 85% of malaria cases and 90% of malaria deaths occur in Africa, south of Sahara. In Africa, the vast majority of cases and deaths occur in young children (World Health Organization, 2010).
Malaria is usually transmitted through the bite of an infected female anopheles mosquito. Plasmodium malariae causes the mildest and most deadly form of malaria infection (Ahiboh et al., 2008). Plasmodium knowlesi is the species of plasmodium most recently identified as agent of human malaria (Singh et al., 2004).
Plasmodium falciparum is the plasmodium species responsible for 85% of malaria cases, The Sporozoites, that is, the infective plasmodial stage is injected together with saliva into subcutaneous capillaries, disappear from the blood within approximately 45 minutes of the bite and then it enters liver parenchymal cells (hepatocytes). Within the hepatocytes, each sporozoite starts a phase of asexual reproduction resulting in the formation of a schizont, which contains thousands of merozoites.
The rupture of mature schizonts generates the liberation of merozoites into the bloodstream. The hepatic phase of parasite development (hepatic schizogony) lasts on average between 5.5 (Plasmodium falciparum) and 15 days (Plasmodium malariae). In case of Plasmodium vivax and Plasmodium ovale infections, a proportion of parasites may remain dormant in hepatocytes as hypnozoites for several months up to 5 years.
From the clinical point of view, the hepatic schizogony is asymptomatic, as only a few numbers of liver cells is infected (Gilles, 1993). Once in the bloodstream, merozoites reach and invade red cells rapidly to start a process of asexual multiplication (erythrocyticschizogony). Within the red blood cell, merozoites mature to trophozoites and schizonts, which then rupture liberating the new generation of merozoites to invade other red blood cells and thus continue the erythrocytic cycle.
At the time of schizont rupture, the release of malaria parasites and erythrocytic material into the circulation induce the pathophysiology process of malaria and the onset of symptoms. The activation of the cytokine cascade is responsible of many of the symptoms and signs of malaria.
History of Malaria Parasite
The parasite responsible for malaria has been in existence for 50,000–100,000 years, and the population size of this parasite did not increase until about 10,000 years ago, concurrently with advances in agriculture (Harper and Armelagos, 2011) and the development of human settlements. Malaria parasite in humans looks similar to the parasite in chimpanzees. Evidences suggests that the Plasmodium falciparum malaria may have originated in gorillas. (Durand, 2011).
Malaria in Rome was pervasive that it was referred to as “Roman fever” (Sallares, 2002) and it may have led to the decline of the Roman Empire (Gomzis, 2002). Various regions in ancient Rome were considered to be at risk of this disease because of the unpleasant conditions present for malaria vectors.
These areas such as southern Italy, the Island of Sardinia, the Pontine Marshes , the lower regions of coastal Etruria and the city of Rome along the Tiber. The presence of stagnant water in these places was preferred by mosquitoes for breeding grounds. Irrigated gardens, swamp-like grounds, runoff from agriculture, and drainage problems from road construction led to the increase of standing water. (Hays, 2005)
British doctor Ronald Ross received the Nobel Prize for Physiology or Medicine in 1902 for his work on malaria.
The term malaria was derived from the Medieval Italian: mala aria —\” bad air\”; the disease was originally called ague or marsh fever due to its association with swamps and marshland. (Recter, 1999). The term first appeared in the English literature about 1829. (Richar, 1944). Malaria was once common in most of Europe and North America, (Lindermann M, (1999) where it is no longer endemic, (Gratz and WHO, 2006) though imported cases do occur. (Webb, 2009).
Scientific studies on malaria made their first significant advance in 1880, Constantine in Algeria, observed parasites inside the red blood cells of infected people for the first time. He, therefore, proposed that malaria is caused by this organism, the first time a protist was identified as causing disease. For this and later discoveries, he was awarded the 1907 Nobel Prize for Physiology or Medicine.
A year later, Carlos Finlay, a Cuban doctor treating people with yellow fever in Havana, provided strong evidence that mosquitoes were transmitting disease to and from humans.(Tran and Sung, 2008) This work followed earlier suggestions by Josiah C. Nott, (Chernin, 1983) and work by Sir Patrick Manson, the \”father of tropical medicine\”, on the transmission of filariasis. (Chernin, 1977).
Types of Malaria Parasites
There are five species of Plasmodium (single-celled parasites) that can infect humans and cause illness:
Plasmodium falciparum (or P. falciparum)
Plasmodium malariae (or P. malariae)
Plasmodium vivax (or P. vivax)
Plasmodium ovale (or P. ovale)
Plasmodium knowlesi (or P. knowlesi)
Falciparum malaria is potentially life-threatening. Patients with severe falciparum malaria may develop liver and kidney failure, convulsions, and coma. Although occasionally severe, infections with P. vivax and P. ovale generally cause less serious illness, but the parasites can remain dormant in the liver for many months, causing a reappearance of symptoms months or even years later.
Prevalence of Malaria
Malaria cases in Europe have dropped from a peak of over 90,000 in 1995 to zero in 2015, according to the World Health Organization. This marks an important milestone in efforts to eliminate malaria globally. Nine countries in the European region had been affected by malaria, with Tajikistan and Turkey having the most cases (World Health Organisation, 2015).
Progress against malaria in Europe was the direct result of an agreement between affected countries to shift focus from prevention to elimination. The WHO attributes success to improved surveillance systems, better mosquito control, and greater collaboration across borders. Other regions will undoubtedly try to replicate these strategies as efforts ramp up to eliminate malaria globally (World Health Organisation 2015).
The WHO is quick to warn that the achievement in Europe is “extraordinary but fragile”. Malaria was previously eliminated from Europe in the 1970s, but returned in the 1980s. Without a sustained commitment it would be easy for malaria to reassert itself in the region, especially as international focus shifts to other parts of the world (World Health Organisation, 2015).
Plasmodium Malaria parasites belong to the genus Plasmodium (phylumApicomplexa). In humans, malaria is caused by Plasmodium falciparum , Plasmodium malariae, Plasmodium ovale , Plasmodium vivax and Plasmodium knowlesi (Reeder and Collins, 2012). Among those infected, Plasmodium falciparum is the most common species identified (~75%) followed by Plasmodium vivax (~20%). (Behrens, 2012).
Although Plasmodium falciparum traditionally accounts for the majority of deaths, (Talwar,2009) recent evidence suggests that Plasmodium vivax malaria is associated with potentially life-threatening conditions about as often as with a diagnosis of Plasmodium falciparum infection. (Baird, 2013) Plasmodium vivax proportionally is more common outside Africa. (Reeder,2012) .
There have been documented human infections with several species of Plasmodium from higher apes ; however, except for Plasmodium knowlesi —a zoonotic species that causes malaria in macaques (Collins,2012.)—these are mostly of limited public health importance. (Collins and Barnwell, 2009).
Clinical diagnosis is based on the patient’s symptoms and on physical findings at examination. The first symptoms of malaria (most often fever, chills, sweats, headaches, muscle pains, nausea and vomiting) are often not specific and are also found in other diseases (such as the “flu” and common viral infections).
Likewise, the physical findings are often not specific (elevated temperature, perspiration, tiredness). In severe malaria (caused by Plasmodium falciparum), clinical findings (confusion, coma, neurologic focal signs, severe anemia, respiratory difficulties) are more striking and may increase the index of suspicion for malaria. If possible, clinical findings should always be confirmed by a laboratory test for malaria (CDC-d, 2012).
Signs and Symptoms
The signs and symptoms of malaria typically begin 8–25 days following infection, (Wellems, 2010). But may occur later in those who have taken antimalarial medications as prevention. (\”Malaria: An update for physicians\”). Initial manifestations of the disease—common to all malaria species—are similar to flu -like symptoms, (Zammarchi, 2012). and can resemble other conditions such as sepsis, gastroenteritis, and viral diseases .(Brehrens,2012).
The presentation may include headache, fever, shivering , joint pain , vomiting, hemolytic anemia , jaundice , hemoglobin in the urine, retinal damage, and convulsions . (Molyneux, 2006). The classic symptom of malaria is paroxysm—a cyclical occurrence of sudden coldness followed by shivering and then fever and sweating, occurring every two days (tertian fever) in P. vivax and P. ovale infections, and every three days (quartan fever) for P. malariae .
P. falciparum infection can cause recurrent fever every 36–48 hours, or a less pronounced and almost continuous fever. (Ferri, 2009). Severe malaria is usually caused by P. falciparum (often referred to as falciparum malaria). Symptoms of falciparum malaria arise 9–30 days after infection. (Zammarchi,2012) Individuals with cerebral malaria frequently exhibit neurological symptoms, including abnormal posturing, nystagmus, conjugate gaze palsy (failure of the eyes to turn together in the same direction), opisthotonus, seizures , or coma .( Zammarchi,2012).
Prevention and Control
The major way possible to reduce the transmission of malaria at community level is Vector control.. It is the only means by which malaria transmission can reduced a very high level to a low level.. For individuals, personal protection against mosquito bites represents the first line of defense for malaria prevention.
There are two forms of vector control which are effective in a wide range of circumstances. They include: Insecticide-treated mosquito nets (ITNs) and Long-lasting Insecticidal nets (LLINs). The Long Lasting insecticide nets are the preferred form for public health distribution programs.
WHO recommend coverage for all at-risk persons; and in most settings. The most cost effective way to achieve this is through provision of free LLINs, so that everyone sleeps under a LLIN every night. Indoor spraying with residual insecticides: indoor residual spraying (IRS) with insecticides is a powerful way to rapidly reduce malaria transmission. Its full potential is realized when at least 80% of houses in targeted areas are sprayed.
Indoor spraying is effective for 3-6 months, depending on the insecticide used and the type of surface on which it is sprayed. Dicholoro Diphenyl Trichloroethane (DDT) can be effective for 9-12 months in some cases (WHO, 2015). Longer-lasting forms of existing IRS insecticides, as well as new classes of insecticides for use in IRS programmes, are under development. Antimalarial medicines can also be used to prevent malaria (WHO, 2015)