New tools to fight sleeping sickness

By Gladys Kalibbala

Mark Biong Deng, a student from South Sudan studying in Kampala, suffered from what was for long thought to be malaria. But strangely, all tests for malaria turned out negative and it took experts time to discover it was another problem. It was sleeping sickness.

Fortunately, doctors had an idea of the exact type of the disease basing on where he comes from.

Sleeping sickness, also known as Human African Trypanosomiasis (HAT) is an infectious disease caused by a parasite known as trypanosome which is transmitted by infected tsetse flies.

According to doctors, people suffering from this disease will die if they are not treated. One gets sleeping sickness through the bite of an infected tsetse fly, which is also a carrier to animals.

Dr. Charles Wamboga, coordinator for National Sleeping Sickness Control Programme at the ministry of health explains that the disease occurs in 40 out of 112 districts in Uganda where about 10 million people are at risk of infection.

The disease that is endemic in 36 sub-Saharan African countries is believed to be among the Tropical Neglected Diseases (TNDs). Wamboga explains that a blood test is the only way to tell that someone has sleeping sickness.

Unfortunately, Uganda is the only country with two forms of this disease where T.b.‘Gambiense’ also known as the chronic form is found in West Nile region while T.b.‘Rhodesiense’ also known as the acute form is based in south-eastern region.

“It’s a worrying situation where the two forms are only separated by a distance of about 100 kilometers and therefore an urgent need to stop the merger,” Wamboga says.

Current diagnostic techniques

Wamboga explains the current diagnosis techniques are not sensitive enough and therefore not easy to use. The diagnosis had been limited to only four health facilities where it required specialized health workers and electricity.

Many health centres in rural areas do not have power yet the drugs used need to be kept under cold conditions which require power.

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Test kits used in the new diagnostic strategy to fight Gambiense sleeping sickness in West Nile.

“This has left a number of patients to stay long before a correct diagnosis is made, ending up in the advanced or second stage of the disease. At the same time, they travel for long distances to access the services,” Wamboga laments.

He further reveals that in 2012, all patients treated were in the second stage – where the disease had already penetrated the brain.

Launch of new diagnosis

Government, in partnership with Foundation for Innovative New Diagnostics (FIND), recently launched a new rapid innovation to be used with ease and regarded to be highly sensitive.

According to the agreement signed in the deal, the innovation targets to intensify surveillance and control of t.b. ‘Gambiense’ in West Nile.

Wamboga, who is the Principal investigator in this new project, explains that the strategy which based on passive screening will enable early identification and treatment of a large proportion of sleeping sickness cases that may be present, hence avoiding disease transmission.

How the new diagnosis works

According to Dr. Abbas Kakembo who has dealt with sleeping sickness for many years, the new rapid test kits can be kept even in a cupboard. Better still, the test will not require specialized health workers as any health worker at the centre can be trained briefly on how to handle it.

Previosuly, only four health facilities have been testing the disease. The new diagnosis is being implemented in 166 health centres across the t.b. ‘Gambiense’ sleeping sickness belt of Uganda.

Wamboga explains that tests will be done in three different stages where 154 Health centres (RDT facilities) will deal with the rapid tests. Once found positive, the patient will be referred to parasitology facilities (these will be nine) which will be tested further by microscopy.

At this stage if the disease is confirmed, the patient will be staged and later treated at a health centreIV4.

In case the microscopy is negative after the rapid test had shown positive, a buffy coat sample will be prepared, dried on a filter paper and transported by motorcycle to the third stage.

“Motorcycles, which have already been provided, will be checking on parasitology facilities every after two weeks in order to transport the samples,” explains Wamboga.

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Lumbar puncture is done on a patient of sleeping sickness to determine the stage of the disease.

This third stage referred to as Loop-mediated isothermal amplification (LAMP) of parasite DNA is a molecular test with high sensitivity and specificity. LAMP test results will be communicated to health centres that registered the patient and if they are confirmed positive they will then be treated. 

The LAMP test will be carried out in three hospitals, namely Moyo, Yumbe and Omuge health centre.

 Dr Kakembo explains that unlike tests of t.b. ‘Rhodesiense’ where parasitaemia is usually high enough for parasites to be seen by direct examination of blood under a light microscope, it is different with ‘Gambiense’.

“The number of parasites in t.b. ‘Gambiense’ infections is often below the limit of detection of the most sensitive methods that are in clinical use,” he says, adding that the new method will help a lot in identifying the patients where health workers will receive minimal training while the kits will remain stable under field conditions.

Prof. Joseph Ndung’u, head of FIND explains that the new diagnostic rapid test kits detect host antibodies to infection in population that are at risk.

“The test is done on fresh blood obtained from a finger prick and no instrument or electricity is required,” he says.

Disease stage crucial

Dr. Kakembo underlines the importance of knowing the stage of the disease as different stages receive different drugs. “During the first stage where the parasites are still in the blood and lymphatic system, treatment is relatively safe and cheap.”

 Kakembo further reveals that by the second stage, the parasites have penetrated the central nervous system, resulting into a long expensive treatment while the drugs are too toxic.

The stage of the disease is determined by a lumbar puncture test where fluid is picked from the spinal cord and later checked to confirm the stage.