Environmental factors for transmission of Soil Transmitted Helminthiasis in school age children in Zambia

Soil Transmitted Helminthes (STHs) infections fall under a group of diseases known as Neglected Tropical Diseases (NTDs).

STHs are among the commonest infections occurring worldwide and affect the poor in developing countries [1]. STHs infections are transmitted via the worm egg s which are present in human fa ces which contaminate soil in areas where personal hygiene and sanitation are poor. STHs comprise the following worms; Ascaris lumbricoides (large intestinal round worm), Trichuris trichiura (whipworm), and Necator americanus and Ancylostoma duodenale (hookworm). It is estimated that two billion people globally are infected with STHs [2]. Another 3.5 billion people worldwide are at risk of contracting these infections. Sch ool age children are most affected persons in endemic areas. About 1.4 billion people are infected with A.lumbricoides [3)] while 576 to 740 million individuals are infected with hookworm [4, 5]. With ascariasis, the most affected populations are in Sub -Saharan Africa, Latin America, and Asia [4, 6, 7]. Infection with STHs may lead to disease depending on the number of worms in the infected individual. Individuals with light infections usually are asymptomatic while individuals with heavy infections may ha ve symptoms such as intestinal manifestations (diarrhea, abdominal pains, and intestinal obstruction), general malaise, weakness, impaired cognitive function and physical development, and anaemia [8]. With STHs there is neither direct person to person tra nsmission nor infection from fresh faeces (WHO, 2015). This is because the eggs of these worms that are passed in faeces need about three weeks, depending of the species, to either mature into infectious stage or develop into larvae in the soil. A.lumbrico ides eggs, for example, can survive in the soil for prolonged periods and prefer warm, shady, moist conditions under which they survive sometimes up to ten years [9]. Therefore soil and climatic conditions will determine the distribution of particular STHs in any given locality [10].

In our previous the study entitled “Evaluation of Dipstick Dye ImmunoAssay in the diagnosis of Schistosoma haematobium infection in school children in Zambia” that we conducted in July 2014 in Nchelenge and Luanshya district s of Zambia, whose findings are reported somewhere, we found that the prevalence of ascariasis in school children was significantly higher in Luanshya than in Nchlenge (P<0.05) while the prevalence of hookworm infection in the same school children was significantly higher in Nchelenge than in Luanshya (P<0.05). This observation leads us to propose that there are Page | 55 environmental factors responsible for the differences in the transmission of the two worm infections in school age children i n the two districts.

Following the above observations we conducted a study entitled “Identification of soil and climatic factors responsible for the varied distribution of Soil Transmitted Helminthes in Nchelenge and Luanshya districts of Zambia” in July 2015. The aim of this study was to establish environmental factors responsible for the varied transmission of soil transmitted helminthes (STHs) in school children in Nchelenge and Luanshya districts of Zambia. The objectives of the study were to: compare the selected soil prop erties between Nchelenge and Luanshya districts, characterize the geographical positions of Nchelenge and Luanshya districts in terms of latitude, longitude and altitude, compare the selected climatic variables between Nchelenge and Luanshya districts, and make appropriate recommendations on how to effectively control STHs, based on the identified environmental factors, to the Ministry of Health and Ministry of Community Development Mother and Child health.

In this article we present the findings from the above study.