Descriptive epidemiology is based on the 5Ws, which include what, who, where, when, and why. These variables allow epidemiologists to understand and describe the health status of a population, identify populations at increased risk of disease, characterize which months and areas have the most and least cases of the disease, and make assumptions about the etiology and possible risk factors. Thus, this paper reflects the basic epidemiological patterns of malaria.
Person
Such factors as age, gender, race, immune status, marital status, socioeconomic status, occupation, as well as leisure time, use of drugs and other substances, and access to health care are characteristics that influence the prevalence of the disease in a particular population group. Populations at higher risk of malaria include young children, pregnant women, those infected with HIV and AIDS, and migrants from endemic areas. Children from six months to five years of age, who have no immunity to the disease, suffer the most from malaria. According to WHO (2018), they account for two-thirds of malaria deaths. Moreover, malaria leads to high miscarriages and maternal mortality rates of 10-50%. Harris (2019) notes that 200 000 infants die each year from maternal malaria infection during pregnancy.
Moreover, some groups are relatively immune to malaria. According to Harris (2019), blacks of West Africa are genetically insensitive to the causative agent of three-day malaria; individuals with a deficiency of the glucose-6-phosphate dehydrogenase enzyme are relatively resistant to the causative agent of tropical malaria. Heterozygous carriers of hemoglobin S (HbS) and homozygous individuals with sickle cell disease are relatively resistant to tropical malaria parasites (Harris, 2019).
Place
Mosquitoes of the genus Anopheles, which are carriers of malaria, live in almost all climatic zones except the subarctic, arctic zones, and deserts. However, for there to be a risk of contracting malaria, conditions are required for their rapid reproduction and transmission of the malarial plasmodium. Such conditions are achieved in those areas where there are no low temperatures, there are swamps, and there is a lot of precipitation. Therefore, malaria is most widespread in the equatorial and subequatorial zones, which account for the countries of Africa, Southeast Asia, and South America. 94% of malaria cases are reported in Africa, half of them in six countries: Nigeria, Congo, Tanzania, Burkina Faso, Mozambique, and Niger (WHO, 2018). However, malaria is reported in Asia, Latin America, and, to a lesser extent, in the Middle East and parts of Europe. Malaria transmission continues in 97 countries and territories.
Time
Since Anopheles mosquitoes breed in water, the prevalence of infection is often seasonal, depending on precipitation, temperature, and humidity. The peak incidence occurs during and immediately after the rainy seasons. In temperate zones, the malaria transmission season is 1.5–3 summer months; in subtropical zones, it increases to 5–8 months; in tropical zones, the year-round transmission of malaria is possible (Harris, 2019). It is noteworthy that the socio-economic policies of countries influenced the spread of malaria. Even 80 years ago, malaria was spread throughout the globe (WHO, 2018). Still, thanks to the development of the economy and medicine, nowadays, the disease has been defeated in half the countries of the world and is rampant only in hot developing countries.
References
Harris, R. E. (2019). Epidemiology of chronic disease: Global perspectives (2nd ed.). Jones & Bartlett Learning.
WHO. (2018). World malaria report at a glance. Web.