The ecology of disease which is believed to have begun from humans is concerned with how species interactions and abiotic components of the environment affect patterns and processes of disease. It explores the dynamics and evolution of diseases for example the viral, bacterial and fungal in natural and managed ecosystems. Therefore, the human ecology of disease can be defined as the study of the relationship or pattern of interaction between humans and their natural, social and built environments.
Human ecology defines relationships between people and their environment. Human ecology consists of those biological, cultural and environmental factors that influence the state of human populations (triangle of human ecology) which proposes that an individual’s population, habitat and behaviour together are interrelated and affect ones’ state of health as shown in figure 1 below.
From the diagram above (figure 1),the habitat here refers to the environment which humans live and work in for example houses, workplaces and health care service areas. Population then refers to the potential hosts of the disease and elements under population include genetic resistance, nutritional status, immunological factors and age. Behaviour furthermore entails culture perceptions, social norms and education (Del Casino Jr, 2017).
Malaria is defined as a mosquito borne infectious disease of humans and other animals caused by parasitic protozoans of the genus Plasmodium transmitted via a bite from an infected female Anopheles mosquito (Barry, 2005). Relationship between humans and malaria disease can be interlinked with the triangle of human ecology.
Malaria kills nearly a million people a year. This figure shows the immense and persistent burden of malaria hence making control of production or prevention of the disease vital in global public health. Interventions implemented to reduce or minimise production of the disease especially to humans include the use of insecticide treated nets for those more at risk of malaria, antimalarial drugs for those confirmed to have malaria and indoor residual spraying. Its cause or result was due to the interactions between vectors, parasites, human beings and various environmental and anthropogenic determinants. There are four plasmodium species responsible for malaria namely falciparum, vivax, ovale and malariae with falciparum being the most virulent and responsible for majority of malaria related mortality.
Topography influences human decisions on where to build their houses whereas drainage systems however determines their source of drinking water. Socio economic factors on the other hand determine what materials will be used to construct a house, cultural beliefs about the cause of the disease also influences health seeking behaviour. All of these factors interact in different ways and can lead to either increased or reduced risks of malaria among individuals.
Malaria in terms of households is combated or promoted by factors such as type of walls, roofs, floors, windows, doors and even the number of household members in that house. These factors together with conditions of the household like cracks, roof openings, stagnant water and the distance of the houses to swamps could allow entry of mosquitos. Because of the drainage systems, some houses are built on these flat swampy areas, closer to the breeding areas for these mosquitos hence production of the disease. However, although some are built on these swampy areas, keeping medicine at home and preventative measures such as mosquito nets can reduce or prevent the disease.
Half of the global population is known to be at risk of malaria infection. Malaria’s noted high risk population biologically are infants that are 6-12 months, young children, pregnant women and non-immune people for example travellers, labourers and populations that move from low to high transmission areas as well as people with compromised immune systems for example those living with HIV/AIDS. Malaria is not gender specific so there is equal exposure to malaria infection amongst men and women(Manandhar et al., 2018). The reason why malaria targets these groups is due to their immunities. A good immunity means one is able to beat and fight the number of diseases whereas a weak immunity makes one more vulnerable to ill health.
For pregnant women, infection rate is higher because of their decreased immunity with the rates higher in the first and second parity and lower rates in later pregnancies(Steketee et al., 2001).For children however, the reason why they are at risk of infection is because they have not lived long enough to develop immunity against various diseases and infections as compared to adults. For the case of adolescents, particularly females, they are more vulnerable to malaria for example in the Sub-Saharan African countries because they are parasitaemic and anaemic when they first become pregnant. However in despite of pregnancy, adolescent girls generally have a higher parasite rate than women over the age of 19(Brabin and Brabin, 2005)
According to (Molyneux et al., 2018), health and poverty are related. Poverty interacts with health in many ways and undermines a whole range of human capabilities, possibilities and opportunities. Poverty leads to increased dangers to health because working environments of poorer people have more environmental risks for illnesses and diseases. Poor people enduring poverty also tend to be less educated hence they have less knowledge about activities to promote their health and when to access health care facilities. For the case of malaria, malaria may result in poverty and in turn poverty may aggravate malaria transmission. In terms of the habitat, areas where malaria prospers most, humans’ societies have prospered least in those areas(Sachs and Malaney, 2002). The gross domestic products per capita globally shows a striking correlation between malaria and poverty, malaria endemic countries also have lower rates of economic growth for example countries in southern Africa such as Botswana,Zambia,Angola (developing countries).
(Chirebvu et al., 2016) study for Botswana indicated that malaria occurs in distinct seasons and epidemics that may be caused by a range of factors such as movement and displacement of human populations, breakdown of control activities, environmental changes and climatic factors. However malaria is recognized as a disease most sensitive to climate change because temperature, humidity and rainfall affect the degree of malaria transmission. A study in Botswana concluded that rainfall and standardised annual malaria incidence divergence from December to February were significantly related to sea surface temperatures. The above average rainfall in Botswana of 1992-1993 was associated with a very high malaria season whereas rainfall in December to February 2000 was the highest and yet Botswana experienced a lower than expected malaria incidence during that period(Thomson et al., 2005). Malaria is more prone up north in Botswana, specifically in the Ngamiland and Okavango district because in relation to their habitat, they are forest areas and there is the Okavango Delta which has large field of standing waters thus promoting the number and range of vector habitats that enhance potential exposure to infection. However, for the Okavango Delta, this is not the case observed because of their very low human population density.
In terms of behaviour, malaria transmission is also blended by other risk factors such as changes in human behaviour due to displacement, overcrowding in temporary shelters, poor environmental conditions created by floods, post flood destruction of the living environment and in some areas lowered physical strength due to shortage of food and creation of an environment favouring propagation of malaria infected mosquitos (Chirebvu et al., 2016).
Patterns of exposure that lead to production and or prevention of malaria disease infection often coincide with norms and behaviour. In some areas, sleeping cultures influence malaria infection because men tend to sleep outdoors thus increasing the risk of exposure to mosquitos(Gunn et al., 2018).This issue then relates back to population(gender element specifically) as one would argue that this is the reason malaria is prominent in males. In Africa per say, it is common culture that males are the head of the family therefore they are responsible for the decisions taken within the family. Due to this culture, women are obliged to consult first with their husbands before accessing treatment for themselves and children, attendance and access of resources such as primary health care facilities(Edwards, 2001).
According to (Dike et al., 2006), levels of education affect malaria treatment seeking and possible prevention measures. Higher education levels is associated with improved knowledge and practices in relation to ideal prevention and treatment strategies. Generally, society dwells on the issue that women have lower educational literacy than males, leading back to the element of population (gender) that may support for instance the reason females are more infected than males because it affects females’ ability to identify signs and symptoms of malaria and access to treatment.
There is an influence of the production or prevention of diseases, for this case malaria, due to the relationship between human beings and their environment. Malaria will always be linked to the population at risk or vulnerable, behaviour of the people and the habitat they reside in.