Decreasing Shigellosis-related Deaths | CDC EID

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Volume 16, Number 11–November 2010
Research
Decreasing Shigellosis-related Deaths without Shigella spp.–specific Interventions, Asia

Pradip Bardhan, A.S.G. Faruque, Aliya Naheed, and David A. Sack Comments to Author
Author affiliations: International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh (P. Bardhan, A.S.G. Faruque, A. Naheed); and Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA (D.A. Sack)

Suggested citation for this article

Abstract
In 1999, a review of the literature for 1966–1997 suggested that ≈1.1 million persons die annually of shigellosis, including ≈880,000 in Asia. Our recent review of the literature for 1990–2009 indicates that ≈125 million shigellosis cases occur annually in Asia, of which ≈14,000 are fatal. This estimate for illnesses is similar to the earlier estimate, but the number of deaths is 98% lower; that is, the lower estimate of deaths is associated with markedly reduced case-fatality rates rather than fewer cases. Shigella spp.–related deaths decreased substantially during a period without Shigella spp.–specific interventions. We speculate that nonspecific interventions, e.g., measles vaccination, vitamin A supplementation, and improved nutrition, may have led to the reduced number of shigellosis-related deaths.

In 1999, Kotloff et al. reviewed the literature to estimate the global incidence of shigellosis. On the basis of studies published during 1966–1997, they estimated ≈1.1 million shigellosis-related deaths annually, resulting from ≈164.7 million cases. Of these, ≈163.2 million cases occurred in developing countries, ≈80% of which occurred in Asia (1). These high estimates of illness and death have increased interest in identifying interventions, including new vaccines, that might reduce these astonishing numbers (2–5).

Several changes have occurred that might have altered this incidence. Shigellosis might be increasing because of increasing populations in Shigella spp.–endemic areas; because of increasing resistance to antimicrobial drugs among shigellae, especially in S. dysenteriae type 1 (the Shiga bacillus) (6–8); or because of increasing rates of HIV infection and AIDS in many countries, which might be influencing shigellosis incidence. On the other hand, incidence might be decreasing because of improved nutrition in many countries, improved delivery of healthcare in some areas, and more widespread use of measles vaccine (9,10) and vitamin A supplementation (11), which might reduce the severity of intestinal infections. The availability of fluoroquinolones, often used without prescription, also might lead to changing treatment practices because families might use antimicrobial drugs earlier during diarrheal illness or for other illnesses (12).

Shigellosis incidence might also have changed because of the overall reduction in diarrhea-related deaths through case management, including rehydration therapy and proper feeding (13). Because shigellosis is not primarily a dehydrating condition, hydration is not critical for patients with dysentery. Nonetheless, the consistent use of oral rehydration therapy for diarrhea may reduce illness from the persistent effects of repeated episodes of diarrhea, which is common in developing counties.

Thus, at the request of the World Health Organization, we reviewed the literature for 1990–2009 to estimate the current incidence of shigellosis. The earlier study by Kotloff et al. attempted to extrapolate from data from developing countries; however, most of the data were from Asia. Because the epidemiology of shigellosis may differ in Africa, we restricted our review to studies in Asian populations.

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Suggested Citation for this Article

Bardhan P, Faruque ASG, Naheed A, Sack DA. Decreasing shigellosis-related deaths without Shigella spp.–specific interventions, Asia. Emerg Infect Dis [serial on the Internet]. 2010 Nov [date cited]. http://www.cdc.gov/EID/content/16/11/1718.htm

DOI: 10.3201/eid1611.090934