Resource availability and cholera treatment strategies in Somalia

Cholera in Somalia: Resources Determine Strategy

Cholera in Somalia

Cholera Background Information

Vibrio cholerae (cholera) is a Gram-negative bacterium that threatens human health when water and food supplies become contaminated (Weil, Ivers, and Harris, 2012). Its emergence occurs most often in crowded and unsanitary conditions and on average kills approximately 50% of those who develop symptoms and never receive treatment. Death occurs because a toxin secreted by the bacterium is endocytosed by epithelial cells in the small intestine, leading to unregulated cAMP production and chloride secretion into the lumen. The increasing chloride concentration in the lumen forces the body to secrete large amounts of water, potassium, sodium, and bicarbonate, leading to severe dehydration. The amount of fluid lost can reach 1 liter per hour in adults and if not compensated for, death follows in just hours.

The presumed ancestral home of cholera is the Ganges River Delta region, which is now Bangladesh (Mandal, Mandal, and Pal, 2011, 573-575). The first six of seven recognized cholera pandemics over the past two centuries are believed to have originated from this region. The seventh originated in the Celebes Islands of Indonesia in 1961 and from there spread around the world. The Classical 01 biotype is believed to have been the source of the first six pandemics, but may now be extinct, having been displaced by the more virulent 01 El Tor strain. First detected in 1905 in El Tor, Egypt, the 01 El Tor strain is believed to be the dominant biotype causing the current pandemic. A third strain, serogroup 0139, ravaged the Indian subcontinent in 1993 but never attained pandemic potential.

The estimated number of reported and unreported cases annually is believed to be 3 to 5 million, resulting in over 100,000 deaths (Weil, Ivers, and Harris, 2012, p. 2-5). The seventh cholera pandemic is therefore far from under control. More recently, a devastating earthquake in Haiti created a window through which cholera could enter a country with no history of cholera. With only 17% of Haiti's residents with access to adequate sanitation following the earthquake, 439,000 V. cholerae 01 El Tor cases led to 6,200 deaths in just 10 months. The source of this bacterium is believed to be a single asymptomatic United Nations aid worker from Nepal (Enserink, 2011). 75% of all infected individuals remain symptom free, but shed bacterium in their stools for up to two weeks (WHO and UNICEF, 2011).

Cholera Diagnosis

In resource-rich areas the Crystal VC® diagnostic test provides a rapid colorimetric indication of the presence of V. cholerae 01 El Tor and 0139 antigens in stool samples (Weil, Ivers, and Harris, 2012, p. 3). In resource-limited areas, stool samples can be cultured on taurocholatetellurite-gelatin or thiosulfate-citrate-bile salts-sugar agar. If culture media or equipment isn't available a dark-field microscopic examination of the stool for the characteristic motility provides a presumptive diagnosis.

Treatment Guidelines

By the time patients seek medical care they have typically lost 5% of their body weight. If rehydration treatment is started immediately fatalities can be reduced to below 1% (Mandal, Mandal, and Pal, 2011, p. 576). The main treatment is an oral rehydration salt (ORS) solution (WHO and UNICEF, 2006). In severe cases, intravenous fluids are combined with oral rehydration salts, and antibiotics may be used to reduce the duration of symptoms (Weil, Ivers, and Harris, 2012, p. 4). Zinc supplementation reduces stool volumes and diarrhea duration, and vitamin A is recommended for children between 6 mo. And 5 years. Solid food is also recommended and breastfeeding should continue.

Prevention

Water treatment, either chemically or by boiling, helps to reduce the prevalence of this water-borne disease in areas were potable water isn't available (Weil, Ivers, and Harris, 2012, p. 4-5). Hand washing is also effective, especially when preparing food. Two WHO-recommended vaccines have been shown to be 60% and 67% percent effective against 01 El Tor, or 01 El Tor and 0139 strains, respectively. Both could be used to produce a 'herd effect' if only a portion of the at-risk population is vaccinated, and the latter vaccine is cheap enough (U.S.$2 dollars) for use in developing countries.

Summary

Efforts to forestall the next cholera epidemic in Somalia are limited to the most at risk areas in the country, which seems appropriate given that cholera was considered under control at the time and funding for a vaccination program was lacking. Pre-rainy season preparations were based on the scale of the most recent cholera epidemic and limited to AWD treatment, community education, and household hygiene supplies for a limited section of the country. The current status of cholera epidemic prevention and treatment in Somalia is therefore limited primarily to crisis management, rather than prevention, and therefore could not meet demand if another cholera epidemic exceeded predictions.

Research

Enserink, Mark. (2011). Cholera linked to U.N. forces, but questions remain. Science, 332, 776-777.

Mandal, Shyamapada, Mandal, Manisha D., and Pal, Nishith K. (2011). Cholera: A great global concern. Asian Pacific Journal of Tropical Diseases, 4, 573-580.

Weil, Ana A., Ivers, Louise C., and Harris, Jason B. (2012). Cholera: Lessons from Haiti and beyond. Current Infectious Disease Reports, 14, 1-8.

WHO Somalia. (2011). Emergency Humanitarian Action, Weekly Highlights 6 -- 12 August 2011. EMRO.WHO.int/Somalia/. Retrieved 6 Feb. 2012 from http://www.emro.who.int/somalia/pdf/EHA_weekly6-12August_011.pdf

World Health Organization and UNICEF. (2006). Oral Rehydration Salts: Production of the new ORS. (WHO/FCH/CAH/06.1). Geneva: WHO Document Production Services.

World Health Organization and UNICEF. (2011). Water bourne diseases pose lethal threat to children in southern Somalia: Rapid response needed as cholera cases increase. EMRO.WHO.int. Retrieved 6 Feb. 2012 from http://www.emro.who.int/somalia/pdf/Press_Release_WHO_UNICEF_SOMALIA.pdf