Rachel ter Horst: Inspiring progress in the fight against sleeping sickness

Rachel ter HorstBamako, Mali. Leopard print chairs, a rather dark conference room filled mainly with African men dressed in either dark suits or colourful long boubous, with some women and westerners here and there. The 31st biennial International Scientific Council for Trypanosomiasis Research and Control (ISCTRC) was about to start.

On the menu: progress towards elimination of one of the world’s most neglected tropical diseases, sleeping sickness (human African trypanosomiasis [HAT]). Sleeping sickness is a parasitic disease transmitted by the bite of an infected tsetse fly. The disease affects mostly poor populations living in remote rural areas of Africa. If left untreated, HAT is usually fatal. Elimination of the disease implies a reduction in incidence to zero in a defined area (as opposed to eradication, which is a permanent reduction to zero of worldwide incidence, after which intervention measures are no longer needed). Continued intervention measures are required to prevent re-establishment of transmission.

Over the past 10 years, considerable progress has been made in the control of sleeping sickness. In several countries, no cases have been diagnosed for over a decade. In others, especially the Democratic Republic of Congo (with nearly 7200 reported cases in 2009 and over 5600 in 2010; 80% of all reported HAT cases), the Central African Republic, South Sudan, Uganda, and Chad, the annual reported incidence is considerable. However, the real incidence in these countries is not actually known, because some HAT endemic areas are too insecure to access, lack healthcare and surveillance, or both. Médecins Sans Frontières (MSF) has been involved in sleeping sickness treatment since 1986. The organisation tends to go where the disease burden is highest, and national control programme teams or other non-governmental organisations do not go because of war, insecurity, or lack of capacity. While implementing extensive active case finding and providing life saving treatment, MSF advocates enhanced coordinated efforts and research and development into better diagnostic tests and treatments. The current diagnostic test (card agglutination test for trypanosomiasis followed by cerebrospinal fluid microscopy for confirmation and staging) and treatment tools (pentamidine intramuscular injections for stage 1, NECT [nifurtimox-eflornithine combination therapy; includes twice daily eflornithine intravenously for a week] for stage 2) require trained medical and laboratory staff, and are difficult to integrate into primary health care (where available).

The new MSF international mobile HAT team was introduced at the conference. Operating in countries with the highest burden of HAT, the teams will facilitate diagnosis and treatment for neglected populations that are difficult to access, investigate suspected transmission areas, strengthen surveillance capacity, raise awareness and action at national and international levels, and assess and integrate new approaches.

Good news on sleeping sickness diagnostics came from the Foundation for Innovative New Diagnostics (FIND), who presented their hopeful diagnostic pipeline. If all goes well, by late 2012 there could be a rapid diagnostic test for sleeping sickness. A lumbar puncture will still be needed to establish the disease stage of a patient since this determines the choice of current treatments. Research is ongoing into developing a biomarker (neopterin) test that can be performed on blood. If that becomes successful, it would greatly improve feasibility of scale-up and integration of HAT care into the health system.

On the treatment front, a hopeful compound in the pipeline of the Drugs for Neglected Diseases initiative (DNDi), named fexinidazole, was discussed. Clinical trials with patients are planned for early next year. Fexinidazole, a once-daily tablet, will hopefully work for both stages of the disease. Another drug candidate is an oxaborole currently named SCYX7158. The outlook is encouraging, but it is still early days.

Trypanosomiasis not only affects humans, but also livestock such as cattle. Animal trypanosomiasis is called Nagana, a Zulu word meaning “to be depressed.” Since the disease affects livestock and has economic implications, it has caught the attention of many more actors who are coming to the fore. Land cleared of the tsetse fly can be turned into agricultural or grazing land.

Tourists in national parks should not be infected. Huge investments are being made into preventing animal trypanosomiasis, such as cattle spraying, cattle foot baths, insecticide treated fencing, and vector control such as aerial spraying and releasing sterile male tsetse flies.

My mind drifts back to the human disease, with its human implications, and an inspiring message that has started shining through the darkness. Numbers of sleeping sickness cases are steadily decreasing through coordinated efforts. Elimination of this scourge from even the hardest to reach places could become feasible. A good rapid test, effective treatment in tablet form, commitment, action (including surveillance), and investment are the ingredients needed to push sleeping sickness down and keep it down.

Rachel ter Horst is the Medical Advocacy Adviser at Médecins Sans Frontières (MSF)