Tuberculosis is a major public health problem in developing countries, 1 where sputum smear microscopy is the most common technique for diagnosing the disease. This method has limitations, the most serious being inaccuracy, when large numbers of sputum samples are analyzed.2 Hence, alternative diagnostic tools are badly needed. In recent years, researchers have explored the possibility of using trained giant African pouched rats ( Cricetomys gambianus ), to screen sputum samples rapidly and accurately. A recent study 3 reported that 18 of 20 pouched rats could detect the presence of Mycobacterium tuberculosis in sputum samples at least as well as, and more quickly than, trained microscopists using the standard Ziehl Neelsen (ZN) method. 3In 2009, the rats analyzed sputum samples collected from five Direct Observation Treatment Short-Course (DOTS) centers in Dar es Salaam, Tanzania.4 Sputum samples were used to prepare microscope slides that were stained by the ZN method and evaluated under light microscopes by technicians at the DOTS centers. Sputum remaining after smears were prepared was frozen and the samples were sent to Anti-Persoonsmijnen Ontmijnende Product Ontwikkeling (APOPO) for subsequent analysis by the rats. Thus, the rats were used in a context that approximated second-line tuberculosis (TB) screening. This work describes their performance in that capacity.Ethical clearance to conduct the reported research was obtained from the Tanzanian National Institute for Medical Research. The manner in which rats were maintained, trained, and used in evaluating sputum samples is detailed elsewhere. 3,5 In brief, they were rewarded with a mouthful of banana for pausing at sputum samples known to contain M. tuberculosis but not for pausing at other sputum samples. Through such training, they learned to pause reliably only at samples that were positive for TB. In simulated second-line screening the rats worked in a 10-hole stainless steel cage 205 cm long, 55 cm wide, and 55 cm high, shown elsewhere.3 Sputum samples obtained from the DOTS centers and autoclaved to kill infectious microorganisms were presented in small pots located immediately below the holes. The status of samples with respect to microscopy was known and the rats were rewarded with food when they kept their nose in a hole above a TB-positive sample for at least 5 seconds, which defines an indicator response. Indicator responses to samples deemed by microscopists to be TB-negative were of particular interest, because such responses may indicate detection of TB-positive cases initially missed by the DOTS centers.Ten rats evaluated every sample. Any sample reported as TB-negative by a DOTS center but TB-positive by two or more rats was evaluated by a second ZN microscopic analysis performed by a technician in our laboratory. Those cases found positive in this analysis were designated as new case detections. They were reported to the appropriate DOTS Centers for follow-up testing and, if appropriate, treatment.In 2009, 23,101 sputum samples from 10,...

Volatiles released by pathogenic and nonpathogenic mycobacteria, as well as by mycobacteria-relatedNocardiaspp., were analyzed. Bacteria were cultivated on solid and in liquid media, and headspace samples were collected at various times during the bacterial lifecycle to elucidate the conditions giving optimal volatile emission. Emitted volatiles were collected by using closed-loop stripping analysis (CLSA) and were analyzed by gas-chromatography–mass-spectrometry. A wide range of compounds was produced, although the absolute amount was small. Nevertheless, characteristic bouquets of compounds could be identified. Predominantly aromatic compounds and fatty-acid derivatives were released by pathogenic/nonpathogenic mycobacteria, while the twoNocardiaspp. (N. asteroidesandN. africana) emitted the sesquiterpene aciphyllene. PathogenicMycobacterium tuberculosisstrains grown on agar plates produced a distinct bouquet with different volatiles, while liquid cultures produce less compounds but sometimes an earlier onset of volatile production because of their steeper growth curves under this conditions. This behavior differentiatesM. tuberculosisfrom other mycobacteria, which generally produced fewer compounds in seemingly lower amounts. Knowledge of the production of volatiles byM. tuberculosiscan facilitate the rational design of alternative and faster diagnostic measures for tuberculosis.

Two identical leptospiral isolates coded Sh9 and Sh25 obtained from the urine of captive African giant pouched rats (Cricetomys gambianus), destined for use as biodetector of antipersonnel landmines were typed as serovar Kenya using cross-agglutination absorption test and DNA fingerprinting with the insertion element sequences IS1533 and IS1500 derived primers. The two isolates were previously characterized using cultural and serological-microagglutination test as pathogenic leptospires of the serogroup Ballum, closely related to serovars Kenya and Peru. To our knowledge, this is the first reported in-depth characterization of leptospira isolates from Tanzania.

We used giant African pouched rats (Cricetomys gambianus) as land mine-detection animals in Mozambique because they have an excellent sense of smell, weigh too little to activate mines, and are native to sub-Saharan Africa, and therefore are resistant to local parasites and diseases. In 2009 the rats searched 93,400 m(2) of land, finding 41 mines and 54 other explosive devices. Humans with metal detectors found no additional mines. On average, the rats emitted 0.33 false alarm for every 100 m(2) searched, which is below the threshold given by International Mine Action Standards for accrediting mine-detection animals. These findings indicate that Cricetomys are accurate mine-detection animals and merit continued use in this capacity.

Setting. Tanzania. Objective. To compare microscopy as conducted in direct observation of treatment, short course centers to pouched rats as detectors of Mycobacterium tuberculosis. Design. Ten pouched rats were trained to detect tuberculosis in sputum using operant conditioning techniques. The rats evaluated 910 samples previously evaluated by smear microscopy. All samples were also evaluated through culturing and multiplex polymerase chain reaction was performed on culture growths to classify the bacteria. Results. The patientwise sensitivity of microscopy was 58.0%, and the patient-wise specificity was 97.3%. Used as a group of 10 with a cutoff (defined as the number of rat indications to classify a sample as positive for Mycobacterium tuberculosis) of 1, the rats increased new case detection by 46.8% relative to microscopy alone. The average samplewise sensitivity of the individual rats was 68.4% (range 61.1–73.8%), and the mean specificity was 87.3% (range 84.7–90.3%). Conclusion. These results suggest that pouched rats are a valuable adjunct to, and may be a viable substitute for, sputum smear microscopy as a tuberculosis diagnostic in resource-poor countries.