The publication of the Global Burden of Disease Study 2010 (GBD 2010) and the accompanying collection of Lancet articles in December 2012 provided the most comprehensive attempt to quantify the burden of almost 300 diseases, injuries, and risk factors, including neglected tropical diseases (NTDs) [1]–[3]. The disability-adjusted life year (DALY), the metric used in the GBD 2010, is a tool which may be used to assess and compare the relative impact of a number of diseases locally and globally [4]–[6]. Table 1 lists the major NTDs as defined by the World Health Organization (WHO) [7] and their estimated DALYs [1]. With a few exceptions, most of the NTDs currently listed by the WHO [7] or those on the expanded list from PLOS Neglected Tropical Diseases [8] are disablers rather than killers, so the DALY estimates represent one of the few metrics available that could fully embrace the chronic effects of these infections.

Table 1
Estimated DALYs (in millions) of the NTDs from the Global Burden of Disease Study 2010.

Disease	DALYs from GBD 2010 (numbers in parentheses indicate 95% confidence intervals) [1]	
NTDs	26.06 (20.30–35.12)	
Intestinal nematode infections	5.19 (2.98–8.81)	
Hookworm disease	3.23 (1.70–5.73)	
Ascariasis	1.32 (0.71–2.35)	
Trichuriasis	0.64 (0.35–1.06)	
Leishmaniasis	3.32 (2.18–4.90)	
Schistosomiasis	3.31 (1.70–6.26)	
Lymphatic filariasis	2.78 (1.8–4.00)	
Food-borne trematodiases	1.88 (0.70–4.84)	
Rabies	1.46 ((0.85–2.66)	
Dengue	0.83 (0.34–1.41)	
African trypanosomiasis	0.56 (0.08–1.77)	
Chagas disease	0.55 (0.27–1.05)	
Cysticercosis	0.50 (0.38–0.66)	
Onchocerciasis	0.49 (0.36–0.66)	
Trachoma	0.33 (0.24–0.44)	
Echinococcosis	0.14 (0.07–0.29)	
Yellow fever	<0.001	
Other NTDs *	4.72 (3.53–6.35)	


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* Relapsing fevers, typhus fever, spotted fever, Q fever, other rickettsioses, other mosquito-borne viral fevers, unspecified arthropod-borne viral fever, arenaviral haemorrhagic fever, toxoplasmosis, unspecified protozoal disease, taeniasis, diphyllobothriasis and sparganosis, other cestode infections, dracunculiasis, trichinellosis, strongyloidiasis, enterobiasis, and other helminthiases.



Even DALYs, however, do not tell the complete story of the harmful effects from NTDs. Some of the specific and potential shortcomings of GBD 2010 have been highlighted elsewhere [9]. Furthermore, DALYs measure only direct health loss and, for example, do not consider the economic impact of the NTDs that results from detrimental effects on school attendance and child development, agriculture (especially from zoonotic NTDs), and overall economic productivity [10], [11]. Nor do DALYs account for direct costs of treatment, surveillance, and prevention measures. Yet, economic impact has emerged as an essential feature of the NTDs, which may trap people in a cycle of poverty and disease [10]–[12]. Additional aspects not considered by the DALY metrics are the important elements of social stigma for many of the NTDs and the spillover effects to family and community members [13], [14], loss of tourism [15], and health system overload (e.g., during dengue outbreaks). Ultimately NTD control and elimination efforts could produce social and economic benefits not necessarily reflected in the DALY metrics, especially among the most affected poor communities [11].

The Global Burden of Disease Study 2010: Interpretation and Implications for the Neglected Tropical Diseases