Age-related factors influencing the occurrence of undernutrition in northeastern Ethiopia

Undernutrition is a major public health problem on the globe particularly in the developing regions [1]. About 870 million people in the world and slighter fewer than 15% of the population in the developing regions were estimated to be undernourished in 2010-12 [1]. Undernutrition was responsible for the death of 1.5 million children and women in the world in 2010 [2]. The disease is prevalent in Ethiopia [3-6].

Different biological, socioeconomic and environmental factors are reported to affect the dietary intake and nutrient absorption capacity of individuals [7-9]. Helminths are also implicated in affecting host nutrition [10-12]. For example, S. manosni and hookworm infections could cause high blood and micronutrients loss from the intestinal wall [10,11]. Ascaris lumbricoides (A. lumbricoides) and Trichuris trichiura (T. trichiura) may also cause physiological abnormality of the intestinal wall leading to reduced food intake and nutrient absorption [10,11].

As the prevalence and intensity of intestinal helminth infection as well as the biology, socioeconomic and exposure status to environmental risk factors in humans could vary with age, the relationship of undernutrition with these factors could show an age-related patterns [13,14]. However, the strength and age patterns of association of undernutrition with biological, social, economic, environmental and parasitic factors remain uncertain [7-9,12,13]. In addition, most previous studies in Ethiopia assessed the effect of helminth infection on undernutrition in school age children and febrile adult patients [3-5]. However, the information on apparently healthy looking individuals of different age groups would be more helpful to design appropriate intervention strategies to control the disease. Although major risk factors for undernutrition have been investigated in different regions [7-9,12,13], individual factors potentially change in specific areas, age group and over time. Thus, determining risk factors of undernutrition in specific regions and age groups will be vital to design appropriate intervention measures against the problem.

Moreover, few studies have suggested evolutionary relationship between Schistosoma mansoni (S. mansoni) infection and blood type [15,16]. Supporting this notion, an increased prevalence of S. mansoni infection and related morbidity was reported in people with blood types A [17,18] and B [19]. However, others documented insignificant impact of blood type on S. mansoni infection [20,21]. The objective of the current study was to assess the age patterns of relationship of undernutrition with biological, socioeconomic, household and parasitic factors among communities in Harbu Town, northeastern Ethiopia.

A total 484 individuals (mean age = 22.47; age range: 1 to 80 years; male = 36.6%) living in Harbu Town were involved in the study (Table 1). More than 90% of the community in the current study area were self-employed, live in house with mud floor, Muslims religious followers, Amhara in ethnicity, had toilet and used piped water for drinking. Majority (>75%) of the study participants wash their hands before eating and after using latrine.

Out of 484 individuals examined, 31.8% were undernourished and 32.0% were infected with intestinal helminths. The prevalence of undernutrition in the current study decreased with an increase in the age of individuals and was lower in females than males. Several studies in low-income sub-Saharan African countries also documented a higher prevalence of undernutrition in males and children compared to females and adults, respectively [5,13,28-30]. The young children may have bacterial infections resulting in diarrhea which could in turn cause high nutrient loss from their body. On the other hand, older age individuals will usually consume varieties of foodstuffs thereby preventing undernutrition. The country or community specific characters related with culture in the area could also be responsible for the increased prevalence of undernutrition in males in the current study. For example, in the current study area males are more responsible members of the family in generating income and keeping the welfare of the family. As a result, males in the area are more mobile and engaged in activities which could make them lose grater amount of energy. Indeed, studies reported a regional and country specific variation about the difference in prevalence of undernutrition between males and females [31]. The studies documented a higher prevalence of undernutrition in males than in females in sub-Saharan Africa and the reverse in the case of South/Southeast Asia and Latin America [31].

In the current study, the relationship between sex and undernutrition was observed in adults only. Male and female children and adolescents in the study area usually have similar activities (i.e. playing habit) and most are students, and hence a similar level of undernutrition between the two sexes However, a significant variation in terms of activities and responsibilities exist between males and females in the case of adults which could have resulted in difference in prevalence of undernutrition observed. In India, sex specific variation in prevalence of undernutrition was found at all stages of life [32]. Perhaps, there could have been other cultural reasons (e.g. gender discrimination) that may favor one sex but prevent the other from access to sufficient food and health care at all stages of life.

A decrease in the prevalence of undernutrition among preschool age children, who had educated parents and a family with less than 5 members, was observed in the current study. Other previous studies also documented a lower prevalence of undernutrition in children whose parents had better education status and lower number of family people [33,34]. The level of parental practices towards provision of balanced diet and heath/sanitation cares for their children is expected to increase as the level of education status of the parents increase and the number of family members decrease [33,34]. However, the reason why this was not maintained in school age children and in adults could be due to the fact that older age children and adults could give care for themselves. Adults and older age children may eat and keep their sanitation or visit heath centers more often even when they are uneducated or have big family size.

Washing hands before eating was related to a decrease in prevalence of undernutrition in school age children. However, this relationship did not exist in pre-school age children and adults. Unlike preschool age children and adults, school age children living in the area might play in dusts and mud. As a result, washing of hands in this age group will be more advantageous as it will decrease the chance of bacterial and parasitic infection. This in turn decreases nutrients loss due to infection.

The prevalence of undernutrition was similar between individuals who were infected and not infected with helminths. A study documented also lack of correlation of intestinal helminth infection with undernutrition [35]. The effect of helminths on the nutritional status of a host is more pronounced when infections are chronic and heavy [10,36]. All cases of A. lumbricoides and T. trichiura infection in the present study were of light intensity. However, all S. manosoni infections showed heavy intensity. Perhaps, S. mansoni infection in the study participants might be acute. Individuals who were not infected with intestinal helminths might have been infected with other bacterial, viral or chronic infections that could have negatively affected their nutritional status.

The prevalence of undernutrition in the current study was also similar when compared among individuals of different income level, employment status, house floor, ethnic and religious groups as previously reported in some studies [7,8]. Majority (>90%) of the community in the current study area were self employed, live in house with mud floor, were Muslims and Amhara in ethnicity. This might have hindered from detecting significant statistical differences. Furthermore, the life style of the community (e.g. culture and ethinic customs), availability and cost of foods in the area could also explain the current finding.

The intensity of S. mansoni infection was significantly higher among individuals of blood type A compared to those of blood type O. A study in Zimbabwe also documented a higher intensity of S. mansoni infection in children of blood type A compared to those with O type [18]. Indeed, studies showed structural similarity between substances (e.g. N-acetyl-D-galactose polysaccharides) in S. mansoni and blood type A [15,16]. This might help S. mansoni to mask its antigens and escape the host immune in blood type A individuals thereby increasing survival of the parasite in the host. However, studies involving larger samples in high prevalence and intensity areas for S. mansoni infection will be important to make firm conclusion about the impact of ABO blood type on prevalence of S. mansoni infection and other related morbidities. Furthermore, there is a need to make detail investigation as to how blood type A will increase susceptibility of the host to increased intensity of S. mansoni infection.

In conclusion, prevalence of undernutrition was higher in children than in adults and the association of sex and socioeconomic factors with undernutrition varies with age. However, helminth infection was not associated with undernutrition in all age groups. Blood type A was associated with higher intensity of S. mansoni infection. Further study on how blood type A could lead to increased intensity of S. mansoni infection in infected individuals is necessary.