Soil-Transmitted Helminthiasis

Abstract

The human burden of soil-transmitted helminthiasis is highest in subSaharan Africa (SSA) than in other parts of the planet. The major parasites that contribute to the global burden, Ascaris, Trichuris, hookworm, schistosomes, and Strongyloides, and even less known ones such as Oesophagostomum bifurcum and Ternidens deminutus (a.k.a. "false hookworm") all occur in SSA. In this chapter, the symptoms and consequences of infection by these parasites including retarded growth, reduced work capacity, poor school performance, adverse cognitive development, and nutritional and reproductive health problems are described for each parasite. The most at-risk groups for the diseases they cause are also specified. Why then is SSA carrying the highest burden? The answer is the diseases' association with ignorance or lack of awareness, poor personal and environmental hygiene, poverty, impoverished health services, and economic development. These factors are common to these helminths' infections and also explain to a large degree the skewed high prevalence of the diseases in rural African communities. The parasites all share similar basics of the life cycle except for Strongyloides stercoralis which in addition is also capable of autoinfection (i.e., multiplication) in human and of existing as free living and productive adults in the environment, attributes which make it difficult to control. Treatment and challenges with mass drug administration (MDA) with antihelminthics and the urgent need for more sensitive diagnostic tools than the existing ones for scenarios of low-intensity infections and the likelihood of resistance developing with the MDA are highlighted. There are opportunities arising from recent technological advancements such as the availability of genome data of 22 helminth species to be exploited for novel drugs and vaccine design and of IT tools, remote sensing data, and global resource platforms for disease mapping, ecology and epidemiology studies, operational research, and implementation of control programs. What it entailed in conducting a successful and sustainable STH control in a hitherto deprived community in Ghana is presented as a case study.