Neglected tropical diseases

WHO to roll out implementation strategy to eliminate sleeping sickness

Network to coordinate partner and stakeholder activities being elaborated

15 November 2013 | Geneva
Child awaiting treatment at a hospital in Doba, Chad

A remarkable decline in the number of new cases of human African trypanosomiasis (also known as sleeping sickness) over the decade has prompted the World Health Organization (WHO) to begin implementing its elimination strategy in 36 countries in sub-Saharan Africa as early as January 2014.

“The target is to eliminate the gambiense form of the disease as a public-health problem by 2020” says Dr Jean Jannin, Coordinator of the Innovative and Intensified Disease Management unit of the WHO Department of Control of Neglected Tropical Diseases in Geneva. “It means bringing down the incidence of the disease to less than 1 case per 10 000 of the population in at least 90% of the areas where cases exist.”

WHO’s roadmap published in 2012 targets elimination of human African trypanosomiasis by 2020. The 2013 strategy, endorsed by WHO’s Expert Committee earlier this year, aims at integrating activities of specialized teams with those of peripheral health structures such as health centres or dispensaries. Optimal use of existing tools that have proven effective in progressively reducing the prevalence of the disease, affordable antitrypanosomal medicines available through donations, limited geographical distribution of the disease, and increased financial and logistical support from donors are key elements of this strategy.

“Epidemiological knowledge about the two main forms of the disease is better today” says Dr Pere Simarro, Medical Officer at WHO. “We have also completed a mapping exercise that has helped us to locate over 175 000 new cases reported in endemic countries and therefore to better plan and monitor control activities.”

Strengthened control, case reporting and surveillance efforts by national sleeping sickness programmes in endemic countries over the past 10 years have enhanced chances of eliminating the disease. Collaboration between WHO and two of its regional offices – the Regional Office for Africa and the Regional Office for the Eastern Mediterranean – has also contributed to reducing transmission of the disease.

"In the absence of new medicines and tools, we have adapted our control strategies through sustained surveillance and screening in all endemic foci,” says Dr Lorenzo Savioli, Director of WHO’s Department of Control of Neglected Tropical Diseases. “Use of new and safer medicines expected to be available soon will certainly speed up prospects for elimination.”

Collaboration between WHO, Sanofi and Bayer has ensured the availability of medicines free of charge and enabled the systematic screening and treatment of affected populations. In 2013, pledges of support have also come from the Bill & Melinda Gates Foundation and the Belgian Government.

New cases of human African trypanosomiasis have been on the decline since 2000. In 2009, fewer than 10 000 cases were reported for the first time in 50 years. This further dropped to 7139 new cases in 2010 and then to 6743 in 2011. In 2012, a relatively higher figure of 7214 new cases was registered.

In 2009, WHO set up a specimen bank that is available to researchers to facilitate the development of new and affordable diagnostic tools. The bank contains samples of blood, serum, cerebrospinal fluid, saliva and urine from patients infected with both forms of the disease as well as samples from uninfected people from areas where the disease is endemic.

The complexity of the disease means that sleeping sickness may never be eradicated. Despite this challenge, WHO’s ultimate aim is to achieve zero cases beyond 2020.

In order to ensure a better and efficacious coordination of activities, WHO is proposing to establish a ‘WHO network’ of partners and stakeholders to bolster elimination of the disease.

The disease

Human African trypanosomiasis is a parasitic disease transmitted by the bite of an infected Glossina insect, commonly known as the tsetse fly. It is caused by infection with protozoan parasites belonging to the genus Trypanosoma.

The two main forms of human African trypanosomiasis, depending on the parasite involved, are:

  • Trypanosoma brucei gambiense (T.b.g.), which is found in 24 countries in west and central Africa. This form currently accounts for over 98% of reported cases of sleeping sickness and causes a chronic infection. A person can be infected for months or even years without major signs or symptoms of the disease. When symptoms emerge, the patient is often already in an advanced disease stage where the central nervous system is affected.
  • Trypanosoma brucei rhodesiense (T.b.r.), which is found in 13 countries in eastern and southern Africa. Nowadays, this form represents under 2% of reported cases and causes an acute infection. First signs and symptoms are observed a few months or weeks after infection. The disease develops rapidly and invades the central nervous system.

The disease affects mostly poor populations living in remote rural areas of Africa. Left untreated, human African trypanosomiasis is usually fatal. Some 70 million people still live in areas at risk, more than half of whom are in the Democratic Republic of the Congo, which currently accounts for 80% of the total cases reported in Africa.

More on human African trypanosomiasis (sleeping sickness)