Neglected Tropical Diseases: Nigeria at a Crossroads
By Brian G. Blackburn, MD and Michele Barry, MD FACP
Dr. Blackburn is a Clinical Assistant Professor in the Division of Infectious Diseases and Geographic Medicine at Stanford University School of Medicine. Dr. Barry is the Senior Associate Dean for Global Health at Stanford University School of Medicine.
Drs. Blackburn and Barry report no financial relationships to this field of study.
Synopsis: Among African nations, Nigeria contains the greatest number of people infected with neglected tropical diseases (NTDs). Nigeria has made many gains and possesses sufficient resources for NTD control and elimination campaigns, but governmental and non-governmental organizations must continue to move these programs forward and expand to a national scale.
Source: Hotez PJ, et al. Nigeria: "ground zero" for the high prevalence neglected tropical diseases. PloS Negl Trop Dis 2012;6(7):e1600. doi:10.1371/journal.pntd.0001600
NTDs are a group of infectious diseases that are common among the world's poorest people. Endemic to many developing countries, the NTDs not only stem from poverty, but contribute to its perpetuation. Taken together, the burden of NTDs is greater than malaria or tuberculosis, and NTDs trail only pneumonia, HIV-AIDS, and diarrheal diseases as the leading infectious causes of disability-adjusted life years (DALYs) lost globally.1 Although the global budget available to combat NTDs is far lower than for these other infectious diseases, advocacy and funding for NTDs has increased dramatically over the past decade, and is perhaps at its highest level ever. Control and elimination programs, often employing mass drug administration (MDA), have made great strides in lowering the prevalence of these diseases in many areas.
Globally, Africa bears the greatest NTD burden. This review highlights Nigeria, the most populous country in Africa, and containing 20% of its population, which bears the greatest burden of these diseases on that continent. Among the "high-prevalence" NTDs and those controlled by mass drug administration [MDA] programs are soil-transmitted helminths [ascariasis, trichuriasis, hookworm; the soil transmitted helminthes [STHs], lymphatic filariasis [LF], schistosomiasis, onchocerciasis, and trachoma. Nigeria has the highest prevalence in Africa for nearly all of these diseases (see table, below), and is near the top globally. For both onchocerciasis and schistosomiasis, Nigeria has the highest prevalence in the world. These diseases place an enormous burden on Nigeria, and Africa as a whole. In addition to the direct morbidity and mortality for individuals infected with them, they adversely affect maternal-child health and worker productivity, in turn adversely impacting Nigeria's economy and perpetuating the cycle of poverty that so many of the patients infected with these diseases face.
Control and elimination programs for these NTDs utilize low cost, ''rapid-impact'' packages of drugs. Integrated control efforts can target all of these diseases simultaneously with the same infrastructure, thus saving resources - the cost in Africa to combine MDA programs for STHs, LF, onchocerciasis, schistosomiasis, and trachoma is less than US $1 per person annually. With such a program implemented on a national scale, LF, onchocerciasis, and trachoma could possibly be eliminated, and the prevalence of the STHs and schistosomiasis could be reduced substantially. For all of Nigeria, this would probably cost less than US $100 million annually. Because these NTDs actually cause poverty, the economic rate of return for integrated NTD control and elimination would likely be substantial.
Nigeria possesses many resources, with an economy that is Africa's third-largest and ranks 32nd globally. The annual GDP of Nigeria is over US $300 billion, and growing 7-8% per year. However, Nigeria's economy has increasingly depended upon oil - it is now one of the world's leading producers. Unfortunately, oil dependence has led to decreasing diversification, in turn resulting in high rates of youth unemployment and job insecurity. Despite the large financial resources, Nigeria ranks only 158th globally in the human development index (HDI). Between 1990 and 2006, Nigeria regressed in several development indices such as access to safe water and sanitation for its residents.
Encouragingly, Nigeria has made recent gains in NTD control and elimination. Guinea worm (dracunculiasis) cases have decreased from 3.3 million in 1986 (75% of the world's cases at the time) to zero, with the cessation of autochthonous transmission in 2009. Nigeria was scheduled to treat between 3 - 5 million people in 2011 with azithromycin through their trachoma control and elimination program. Over 95% of the 35,000 Nigerian communities at-risk for onchocerciasis have received annual mass ivermectin administration, and transmission has been interrupted in several locales. In Plateau and Nasarawa states in central Nigeria, ongoing ivermectin/albendazole MDA programs have resulted in reductions of onchocercal nodules by 95%, and LF prevalence by 83%. Schistosomiasis control is now being integrated with LF and onchocerciasis elimination campaigns, with six states now receiving targeted praziquantel mass drug administration.
Many of these gains have occurred in collaboration with the World Health Organization (WHO), UNICEF-Nigeria, the Carter Center's Nigeria office, the African Programme for Onchocerciasis Control, and other governmental and non-governmental organizations (NGOs). Nevertheless, much of the Nigerian population still lacks access to the medicines essential for control of these infectious diseases. In 2009, a Nigerian ministry of health program for national NTD control and elimination was initiated. This program focuses on integrated and cost-effective approaches to control / eliminate LF, onchocerciasis, schistosomiasis, STHs, trachoma, leprosy, Buruli ulcer, human African trypanosomiasis, and guinea worm disease.
Nigeria has sufficient wealth and resources to mount an aggressive national campaign for control and elimination of NTDs. It would cost less than 0.1% of the Nigerian GDP to annually target the "high prevalence" NTDs through integrated MDA for STHs, LF, onchocerciasis, and schistosomiasis, possibly along with distribution of long-lasting insecticide-treated bednets, that would target both LF and malaria, as well as the SAFE (surgery, azithromycin, antibiotics, facial cleanliness, and environmental control) strategy for trachoma elimination. Integration of control and elimination programs is clearly the way forward, as this has been shown to decrease costs, improve coverage of these interventions, and makes logistical sense for these diseases which share such similar control and elimination strategies and logistics.2,3 Another key need that must be addressed early in these efforts is to accelerate completion of NTD mapping nationally, so that efforts may be targeted appropriately.
Although the cost of these programs could, at first glance, appear to be a deterrent to Nigerian policy makers, the low proportional cost and expected acceleration of economic development that would result should offset these fears and result in increased advocacy and movement on the political agenda. A national NTD control and elimination program in Nigeria, in conjunction with better access to clean water and sanitation, would strengthen health systems and represent a highly effective pro-poor strategy. Though Nigeria may have a larger population and more resources than most of its neighbors, it can serve as a model for other African countries to follow.
References
- Hotez PJ, et al. Control of Neglected Tropical Diseases. N Engl J Med 2007;357:1018-27.
- Brady MA, et al. Projected benefits from integrating NTD programs in sub-Saharan Africa. Trends Parasitol 2006;22:285-91.
- Blackburn BG, Eigege A, Gotau H, et. al. Successful integration of insecticide-treated bednet distribution with mass drug administration in Central Nigeria. Am J Trop Med Hyg 2006;75:650-655.
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