Soil-transmitted helminths are a serious but understudied health concern in South Africa, requiring immediate attention from the scientific community.

Commentary

Over a billion people in sub-Saharan Africa and developing regions of Asia and the Americas have helminthiasis—a devastating category of diseases caused by parasitic worms (helminths)^1–3, such as roundworms (nematodes), tapeworms (cestodes), or flukes (trematodes). Parasitic helminths can infect the intestinal tract, urinary tract, and blood of humans, and other mammals, leading to serious illness and in some cases permanent disability or death. The most common types of helminthiasis are intestinal and caused by soil-transmitted roundworms, including Ascaris lumbricoides and Trichuris trichiura, and the hookworms Necator americanus and Ancylostoma duodenale^3–6. Schistosomiasis and lymphatic filariasis, commonly known as bilharzia and elephantiasis, respectively, are other less common kinds of helminthiases³.

Most people with helminthiasis live in marginalized, resource-limited communities. Sadly, school-aged children and women of childbearing age, including adolescent girls, are among the most susceptible to chronic helminth infections and are at a greater risk of morbidity than members of other groups⁴. Because of its insidious, chronic nature, helminthiasis often goes untreated, leading to far-reaching social and economic consequences. Those infected with helminths show decreased performance at school and work and are predisposed to permanent disability, cardiovascular disease, and premature death. Helminthiases can also reduce vaccine efficacy and accentuate the morbidity rates of other serious diseases, such as malaria, tuberculosis, and HIV/AIDS^3,7–9. Indeed, a number of studies on African populations have shown that helminth infections increase morbidity rates in HIV/AIDS patients as a result of systemic immune activation^8,10–12.

Reducing the number of helminthiasis infections should, therefore, decrease disease burden and pressure on the health care system, especially in countries with high rates of HIV/AIDS. South Africa, which has the highest prevalence of HIV in the world and the highest rate of HIV-associated tuberculosis has channeled significant resources into fighting both of these diseases, but devotes comparatively little money and effort into combating helminthiasis^13,14. Moreover, of the estimated 6.1 million people living with HIV in South Africa as of 2012, 0.41 million were under the age of 15 (http://www.unaids.org/en/regionscountries/countries/southafrica/), and are, thus, highly susceptible to helminth infections.

Mass drug administration (MDA) programs, involving cooperation between government health departments and major pharmaceutical companies, provide low-cost or free drugs for the treatment of various diseases and are one of the most cost-effective global public health control measures in existence⁵. Moreover, many of the MDA programs are targeted at preschool- and school-aged children; however, children who do not attend school can be overlooked¹. Currently, a major obstacle to implementing cost-effective controls for helminthiasis is the lack of knowledge on the geographical distribution of infection and co-infection^3,15 — a problem that could be easily and quickly solved with some basic research initiatives into helminthiasis. Again, given recent evidence of helminths developing drug resistance^1,16, an alternative to MDA becomes a necessity. Vaccine (which doesn’t presently exist) research and development may thus be the best long-term strategy for sustained control and treatment of helminthic infections^5,17.

To gauge South African research output on HIV and tuberculosis versus that on soil-transmitted helminths, we explored PubMed publication numbers and GenBank deposition data (Table 1). In the past year (July 2013 to June 2014), more than 400 journal articles have been published on HIV in South Africa, most of which have at least one author who is affiliated with a South African research institute. These journal articles cut across diverse HIV research areas, including diagnosis, treatment, vaccine trials, co-infections, mother-to-child transmission, and drug resistance. In comparison, there are very few published studies on soil-transmitted helminths in South Africa (mainly in Western Cape and Kwazulu-Natal). Within the past twelve months, only three journal articles on soil-transmitted helminths in South Africa appeared in PubMed, one of which was lead-authored by a researcher from a Cameroonian institute^18–20 (Table 1). What’s more, there are thousands of HIV genome sequences from South Africans deposited in GenBank but not a single nucleotide sequence exists from a South African soil-transmitted helminth (Table 1). Given these statistics it appears that there is an overall lack of research on helminthiasis, both within and outside of South Africa.

The onus is on scientists, funding agencies, and governing bodies to channel efforts into studies on soil-transmitted helminths. Basic research on helminth evolution, cell biology, genetics, and diversity as well as on the social and environmental effects associated with infections could greatly reduce the burden of HIV/AIDS, tuberculosis, and other major illnesses in South Africa and beyond. Helminth research also represents the first logical step in achieving the 2013 World Health Assembly (WHA) resolution to eliminate soil-transmitted helminths by 2020^1,3.