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MTDU - mobile tuberculosis detection unit

2013-14 Master's dissertation by Lisa Leenders and Evi Vandendriessche

Lisa Leenders -
Evi Vandendriessche -
Supervisor: Prof. Dr. Mic Billet – APOPO

The MTDU (mobile tuberculosis detection unit) is a mobile lab for tuberculosis screening carried out with the help of Gambian pouched rats. Tuberculosis is still one of the most threatening infectious diseases worldwide.  Only HIV/AIDS and malaria kill more people. The mobile unit will be deployed in areas with a high incidence of tuberculosis, and therefore play a part in the fight against the disease. The unit was commissioned by APOPO, a Belgian NGO which specialises in the training of giant pouched rats. These rats are used in the detection of land mines and tuberculosis. APOPO is currently conducting tuberculosis screening in two locations, namely near their head office in Morogoro, Tanzania, and a secondary branch in Maputo, Mozambique. They wanted to develop a mobile service in order to be able to target more people, and the MTDU is the answer to this need.

The reception area
In the reception area, the receptionist accepts sputum samples from people wishing to participate in the screening. Participants prepare the samples in advance, at home, preferably in the morning because the concentration of bacteria in the lungs is highest at this time of day. After receiving the samples, the receptionist registers some general personal information about the participant. This means participants can be notified of the test results later. 

The samples are deactivated prior to their screening by the rats. This is done to prevent accidental contamination of personnel. 

Screening with giant pouched rats 
Ten sputum samples are placed in a screening cage. One of APOPO's Hero Rats will then sniff all the samples one by one, searching for traces of tuberculosis. If a rat detects a contaminated sample, it will sniff at it for five seconds. This is a sign for the trainer to mark the sample as positive. As a reward, the rat gets a delicious piece of banana.

Preparation for microscopic examination 
Positive samples undergo a second screening round under the microscope to verify that the participant is indeed infected with tuberculosis. The samples are first concentrated by means of centrifugation, which makes the microscopic tests much clearer than conventional tests. After centrifugation, the residue of the sample is smeared on a slide and stained.

Microscopic examination
Microscopic examination is performed as in order to verify the results and confirms whether or not the patient is infected with tuberculosis. 

Where will the unit be used?
The MTDU will first be deployed in companies and schools. It can also be used to organise tuberculosis screenings at markets and other events.