Neglected tropical diseases (NTDs) are a group of poverty-associated chronic infectious diseases, which are endemic in poor and rural populations in the developing countries of Africa, America and Asia. NTDs affect over 1.4 billion people worldwide and cause severe morbidity and mortality; their impact in sub-Saharan Africa is comparable to malaria or tuberculosis. The diseases, which include river blindness, leprosy and intestinal worms, are transmitted by insect bites or worms in the soil, and are easily spread in areas with poor sanitation.
Worldwide action against NTDs has accelerated since 2007, when the World Health Organization (WHO) held the first global partners’ meeting on NTDs. There are effective drugs to treat these infections, but international efforts are required to distribute treatments, and there are a shortage of healthcare workers in poor countries. The first WHO report on NTDs, released in 2010, highlighted the progress made in the fight against these diseases; pharmaceutical companies agreed to provide many preventive chemotherapy drugs free of charge, with 705 million people reached in 2009. Progress has also been made in transmission control using pesticides, and in increased access to safe drinking water.
However, the fight is far from over; the WHO report listed the remaining challenges that must be overcome, which include provision of sanitation for all people and addressing the problem of drug resistance. Following this report, the UK government announced more funding for the fight against NTDs at the beginning of 2012, and has agreed an action plan to combat them over the next decade together with pharmaceutical companies, the WHO and the US government. The action plan involves a dramatic increase in drug treatment programs, and aims to eliminate a number of the NTDs, including sleeping sickness and leprosy, by 2020.
In addition to drug control programs, there has recently has been an increasing focus on the nutritional aspects of NTDs. Because NTDs are prevalent in poor populations, they predominantly affect those who suffer from chronic undernutrition. In an opinion article published in BMC Medicine, Andrew Hall and colleagues from the University of Westminster in collaboration with Helen Keller International argue that nutritional intervention programs must be added to chemotherapy to receive the full benefit of treatment. Hall and colleagues describe how drug treatment cannot be fully effective without adequate nutrients to repair damage to the body. Additionally, undernutrition increases susceptibility to infection with NTDs and reduces resistance, and drug treatment alone cannot prevent re-infection with helminths in undernourished individuals. NTDs also cause loss of nutrients themselves; helminth infections give rise to malabsorption, and trichuriasis causes gut inflammation and lack of appetite.
To break away from the cycle of undernutrition and NTD infection, Hall and colleagues propose an integrated control program that includes drug treatment, nutritional rehabilitation and measures to prevent re-infection. As there is potential for nutritional intervention to be added to drug treatment programs, the authors suggest that this could be done relatively easily to restore health in those affected by NTDs.
The study by Hall and colleagues may influence the delivery of NTD control programs in the future. Adding nutritional interventions to the current efforts to combat NTDs could further increase the effectiveness of control programs and add to global efforts to eliminate many NTDs by the end of the decade.