Anti-plasmodial Property Of Moringa Oleifera Seed Extract On Swiss Mice

2.1.3 Epidemiology of Malaria
Around 44% of world population is at risk from malaria (RBMP, 2015). At the beginning of 2016, malaria was considered to be endemic in 91 countries and territories, down from 108 in 2000. According to the latest estimates, 212 million cases occurred globally in 2015 and the disease led to 429, 000 deaths, most of which were in children aged under 5 years in Africa. In 2015, the number of malaria deaths in children <5 years is estimated to be 303, 000 worldwide (WHO, 2016). In the U.S., roughly 1,500–2,000 cases of malaria in recent travelers are reported every year. Pregnant mothers have increased vulnerability to falciparum malaria. In malaria-endemic areas, falciparum contributes to 8-14% of low birth weight, which in turn decreases the chance of a baby’s survival (CDC, 2016).
Almost all deaths (99%) due to malaria are resulted from falciparum. About 4% of estimated cases worldwide are caused by vivax, but outside the African continent this proportion increases to 41%. About 76% of estimated malaria cases in 2015 occurred in just 13 countries. Four countries (Ethiopia, India, Indonesia and Pakistan) accounted for 78% of vivax cases. The malaria case incidence was reduced by 41% and mortality rates by 62% globally between 2000 and 2015.
Irrespective to minimization of the world malaria incidence and prevalence, the burden of morbidity and mortality is high in World Health Organization (WHO) African Region, in which most cases (90%) and most deaths (92%) in 2015 were estimated to occur in this region (WHO, 2016). Not only health related impact but also there is a severe economic burden in terms of lost days of work due to the disease. Of course, malaria is considered to take off 1.3% from the economic growth and 40% of public health expenditure of some African countries. It affects developing countries in many aspects including determent of tourism (Ananya, 2013). Malaria is one of the top ten diseases in Ethiopia (CDC Global Health-Ethiopia, 2016). According to the WHO malaria report in 2016, about 27, 034, 284 populations of Ethiopia live at high risk area for malaria infection. In 2015, Ethiopian Federal Ministry of Health (FMoH) reported 1, 867, 059 confirmed malaria cases and 662 deaths [WHO, 2016]. Despite decreased malaria incidence and mortality rate in Ethiopia by > 40% since 2010, high prevalence was observed in contrast to high household coverage of control interventions (Regasa, 2014, WHO, 2016, Ayalew et. al., 2016). This increment in prevalence is commonly associated with individuals having poor socio-economic status, especially children and female household members (Ayele et al., 2013).  
2.1.4 Life Cycle of Malaria Parasites
The human malaria parasite has a complex life cycle as shown in Figure-1. The life cycle within the mosquito takes approximately 8 to 35 days, after which the parasite is infective. The motile infectious form is passed to humans when the insect bites the skin, probes for a blood vessel from which to feed, releases various vasodilators to increase its chance of finding a vessel and salivate into the blood to prevent clotting. Within 30-60 min of inoculation, the thread-like sporozoites are carried to the liver by the circulatory system. One single Plasmodium sporozoite in one liver cell multiplies into tens of thousands of exoerythrocytic merozoites (Krettli and Miller, 2001; NIAID, 2007; Manitoba, 2015).