Cholera in Sierra Leone: the case study of an outbreak

September 2012

Sierra Leone is in the midst of its worst cholera outbreak in 15 years. As of 19 September, there were more than 19 000 cases reported and 274 deaths. WHO and the Ministry of Health and Sanitation have established a cholera control and command centre to coordinate the response to what has turned into a national emergency.

Dr Azharul Islam Khan, microbiologist from ICDDR,B, laboratory scientist Musu Abu and Sierra Leone's only parasitologist Dr Abdul Kamara  observe the yellow bloom of cholera bacteria, grown from a sample taken from a patient in Freetown.
WHO/Felicity Thompson

When reports of suspected cholera cases first came into Sierra Leone’s Ministry of Health and Sanitation in February, alarm bells sounded. Cholera outbreaks normally occur in the rainy season. But February is the middle of the dry season, and more than 2000 cases had already been reported from three districts.

WHO’s Representative in Sierra Leone, Dr Wondimagegnehu Alemu reacted immediately, assigning seven staff members from his office to work with the government and other health sector partners on the response.

The first challenge was to confirm that the outbreak was indeed cholera. And this was not easy.

“In the beginning, we had reports of cases of acute diarrhoea and vomiting in a significant number of people aged more than five years,” said Dr Alemu. “This prompted further investigation but unfortunately there is very little laboratory capacity and the disease reporting system is weak in this country.”

Detection, treatment and prevention

In the early stages of the outbreak, WHO worked with the Ministry of Health and Sanitation and partners including UNICEF and Médecins Sans Frontières-Belgium to detect and confirm new cases, train health workers in cholera treatment and prevention and send medical supplies to support specially established cholera treatment units. By mid-June, cases began to decrease to fewer than 40 per week.

In late June, however, it began to rain. The epidemic spread rapidly to other districts and the number of cases reported rose to more than 2000 per week in early August. More than half of all cases were in the Western Area where the capital Freetown is located.

A cholera command and control centre

On 16 August, President Koroma declared the situation a “public health emergency”. Ten days later, the Ministry of Health established, with WHO support, a Cholera Command and Control Centre. Building on experience from the 2008 cholera outbreak in Zimbabwe, the centre coordinates the response among the many health partners involved in the relief effort. The Minister of Health and WHO co-chair daily meetings at WHO’s office in Freetown at which the partners discuss the day’s case numbers and other information to plan activities.

WHO has brought in additional experts in epidemiology, surveillance, logistics, social mobilization, water and sanitation from other WHO country offices, from the regional office in Brazzaville and headquarters. Mobilizing international expertise from WHO’s Global Outbreak Alert and Response Network, cholera experts have been sent from the International Centre for Diarrhoeal Disease Research, Bangladesh, and the Health Protection Agency in the United Kingdom. These experts are supporting surveillance and data management, and have been training health workers and laboratory scientists to improve the country’s capacity to manage cholera patients and perform reliable laboratory testing.

Daily updates of cases

A patient recovers in a specially established cholera treatment unit  at Wellington Community Centre on the outskirts of Freetown.
WHO/Felicity Thompson

According to William Perea, coordinator of the Control of Epidemic Diseases unit at WHO, one of the Organization’s most important contributions has been to set up a national reporting network that requires all health centres to submit daily updates of cases.

“This network is essential to identifying disease hotspots that require urgent response,” says Perea. “The system will have long-term benefits for surveillance of all disease outbreaks.”

Disseminating safety messages

WHO has also been supporting the Ministry and partners in disseminating messages about safe drinking water, hand washing and food preparation.

“This not only has the immediate benefit of reducing cholera infection, but will help reduce all diarrhoeal disease, a big killer of children under-five in Sierra Leone,” says Dr Eugene Lam, epidemic intelligence service officer from the Centers for Disease Control and Prevention (USA) working for the Global Polio Eradication Initiative.

Water and sanitation are key

Water and sanitation remain a long-term challenge, particularly in the urban slums where people are at high risk of cholera infection.

“Until there is significant improvement in the water and sanitation infrastructure, Sierra Leone will continue to be vulnerable to cholera, especially in the rainy season,” says Perea. “But even if cholera becomes endemic, there are many things that we can do to make sure that people don’t die from it.”

Life-saving treatment in short supply

Having visited many villages struck by the epidemic, Perea says there is a serious shortage of oral rehydration salts (ORS) solution, the most effective, life-saving treatment for diarrhoeal disease. “People in rural areas know about ORS, but those who need it most can’t get hold of it,” he says.

Since early September, there has been a significant reduction in new cases coming in to some of the cholera treatment centres, particularly in Freetown. In more isolated districts, however, numbers of new cases are still rising. Projections suggest that as many as 32 000 cases could be expected in this outbreak.

“This is a major crisis for a country with a fragile health system recovering from several years of conflict,” says Dr Alemu. “The health sector still urgently needs around US$ 1.2 million to sustain the response operations and help bring this outbreak under control and save lives.

“The already-weak health system is struggling to deal with the additional burden of this outbreak. Health workers are giving priority to treating emergency cases of cholera and this takes resources away from other essential services such as maternal and child health,” he says. “While the rain continues to fall, the infection will keep spreading.”