Although at times in certain individuals poor immunity is inherited by birth or some suffer from autoimmune disorders, for the majority of the population immunity can be improved by healthy nutritious food, maintaining standards of personal hygiene, and a sanitary environment. The strong relationship between malnutrition and infection was originally described by Scrimshaw et al. From this framework, many investigations were done in this area and there is a total agreement among authors that mortality is significantly more elevated in an undernourished child compared to healthy ones.
Bacterial Infection: A bacterial contamination is a proliferation of a harmful strain of bacteria on or within the body. One-third of the world’s population is infected with tuberculosis, the main agent that provokes death among infectious diseases, causing tuberculosis. This infection is particularly influenced by undernutrition and often co-exists with PEM. Gastroenteritis is another example of bacterial infection which causes high mortality among malnourished infants and preschool children causing inflammation of the stomach and persistent vomiting and diarrhea, and weanling diarrhea common among weaned malnourished infants can be cited to associate the relationship between nutritional status and incidence of infection. Pneumonia, meningitis, and food poisoning are also a few illnesses that can be resulting from dangerous bacteria. Noma is an opportunistic infection promoted by extreme poverty that evolves rapidly from a gingival inflammation to mutilating orofacial gangrene, as a result of very complex interactions among malnutrition, infection, and compromised immunity. Fusobacterium necrophorum and Prevotella intermedia are the bacterial pathogens causing noma. Bacterial infections increase the need for protein and other nutrients for a speedy recovery.
Viral Infection: Infection resulting from the presence of a pandemic in the body due to the virus. Depending on the state of health, numerous viruses can infect nearly any form of body tissue, from the brain to the skin. Examples include children with PEM who suffer from influenza and measles. Even though effective vaccines are licensed for measles, it continues to cause death and severe disease in children worldwide. Complications from this viral infection can occur in almost every organ or system.
Parasitic Infection: A parasitic ailment, referred to as parasitic diseases can have an effect on nearly all living organisms, with low immune stature. Malarial parasites cause hemolytic anemia and deplete protein reserves. Hookworm infestation causes blood loss leading to anemia. Ascariasis, small intestine infection is another example instigated by Ascaris lumbricoides, which is a species of roundworm prevalent in areas of poor sanitation and hygiene that interferes with the absorption of nutrients in children. The coexistence between undernutrition and nematode infection encompasses two connecting trails, malnutrition that augments susceptibility to infection and the infection itself that leads to a more accentuated undernutrition. Intestinal nematodes provoke malnutrition causing anorexia and a variety of pathophysiological disturbances in the gastrointestinal tract such as vomiting, diarrhea, and malabsorption. All these put together, affect the ability of the child to acquire sufficient nutrients from the diet. Parasites namely helminths, Giardia duodenalis, Entamoeba histolytica, coccidia, and Schistosoma sp. that affect the nutritional status of the children are mostly transmitted through soil.