Saturday, August 13, 2011

Looks Like the Experts May Be Right

See this article summary from the Lancet regarding the spread of cholera in Haiti in 2011.

Simple interventions could avert thousands of cholera deaths in Haiti.

March 21, 2011

ST LOUIS (MD Consult) - Some simple interventions, such as provision of clean drinking water and expanded access to antibiotics, could prevent nearly a third of the 11,100 cholera deaths that are likely to occur in Haiti this year, new data suggest.

Investigators created mathematical models of cholera transmission on the basis of existing models and fitted the models to incidences for each Haitian province from October 31, 2010, to January 24, 2011.

Using simulations, they assessed trajectories of cholera epidemics during a future 8-month period (March 1 to November 30, 2011) to estimate the effect of interventions entailing provision of clean drinking water, vaccinations, and expanded antibiotic access.

Study results, reported online first in The Lancet, suggested there will be 779,000 cases of cholera in Haiti and 11,100 deaths during the 8-month period, estimates sharply higher than those projected by the United Nations.

The simulations indicated that a 1%-per-week reduction in consumption of contaminated water would avert 13% of the cases of cholera and 14% of the deaths. Vaccination of just 10% of the population would avert 8% of the cholera cases and 8% of the deaths. Finally, expanding antibiotic distribution to all severely dehydrated individuals and half of moderately dehydrated individuals would avert 1% of the cholera cases and 12% of the deaths.

Collectively, the three interventions would avert 22% of the cholera cases and 31% of the associated deaths.

Results further suggested that given present conditions, a decline in the prevalence of cholera in early 2011 was due to natural factors and not to successful interventions.

"The modelling of cholera transmission is challenging and relatively primitive compared with the modelling of many other infectious diseases … [but] the alternative available to Haiti is a best guess … and might underestimate the resources needed to avert future cases and deaths," the investigators write.

"Substantially more cases of cholera are expected than official estimates used for resource allocation," they conclude. "Combined, clean water provision, vaccination, and expanded access to antibiotics might avert thousands of deaths."

"I hope that cholera will be under control in Haiti within a year," writes the author of an accompanying comment. "The more realistic expectation is for endemic cholera to continue for many years, as it has in sub-Saharan Africa since 1970, unless a coordinated effort is mounted with all available resources, including improved water and sanitation, improved case management with appropriate antibiotics, and the use of oral vaccines."

Lancet. 2011.

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