Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are una... more Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are unavailable. In 2014, our pouched rats evaluated sputum from 21,600 Tanzanians and 9,048 Mozambicans whose sputum had previously been evaluated by microscopy, the standard diagnostic for TB. Evaluation by the rats revealed 1,412 new patients with active TB in Tanzania and 645 new patients in Mozambique, increases of 39% and 53%, respectively, when compared to detections by microscopy alone. These results provide further support for the applied use of scent-detecting rats.
This study established evidence about the diagnostic performance of trained giant African pouched... more This study established evidence about the diagnostic performance of trained giant African pouched rats for detecting Mycobacterium tuberculosis in sputum of well-characterised patients with presumptive tuberculosis (TB) in a high-burden setting. The TB detection rats were evaluated using sputum samples of patients with presumptive TB enrolled in two prospective cohort studies in Bagamoyo, Tanzania. The patients were characterised by sputum smear microscopy and culture, including subsequent antigen or molecular confirmation of Mycobacterium tuberculosis, and by clinical data at enrolment and for at least 5-months of follow-up to determine the reference standard. Seven trained giant African pouched rats were used for the detection of TB in the sputum samples after shipment to the APOPO project in Morogoro, Tanzania. Of 469 eligible patients, 109 (23.2%) were culture-positive for Mycobacterium tuberculosis and 128 (27.3%) were non-TB controls with sustained recovery after 5 months without anti-TB treatment. The HIV prevalence was 46%. The area under the receiver operating characteristic curve of the seven rats for the detection of culture-positive pulmonary tuberculosis was 0.72 (95% CI 0.66-0.78). An optimal threshold could be defined at ≥2 indications by rats in either sample with a corresponding sensitivity of 56.9% (95% CI 47.0-66.3), specificity of 80.5% (95% CI 72.5-86.9), positive and negative predictive value of 71.3% (95% CI 60.6-80.5) and 68.7% (95% CI 60.6-76.0), and an accuracy for TB diagnosis of 69.6%. The diagnostic performance was negatively influenced by low burden of bacilli, and independent of the HIV status. Giant African pouched rats have potential for detection of tuberculosis in sputum samples. However, the diagnostic performance characteristics of TB detection rats do not currently meet the requirements for high-priority, rapid sputum-based TB diagnostics as defined by the World Health Organization.
Despite its characteristically low sensitivity, sputum smear microscopy remains the standard for ... more Despite its characteristically low sensitivity, sputum smear microscopy remains the standard for diagnosing tuberculosis (TB) in resource-poor countries. In an attempt to develop an alternative or adjunct to microscopy, researchers have recently examined the ability of pouched rats to detect TB-positive human sputum samples and the microbiological variables that affect their detection. Ten published studies, reviewed herein, suggest that the rats are able to detect the specific odor of Mycobacterium tuberculosis, which causes TB, and can substantially increase new-case detections when used for second-line TB screening following microscopy. Further research is needed to ascertain the rats' ability to detect TB in children and in HIV-positive patients, to detect TB when used for first-line screening, and to be useful in broad-scale applications where cost-effectiveness is a major consideration.
Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To pr... more Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To provide an example of the wide range of problems to which operant conditioning procedures can be applied and to illustrate the common challenges often faced in applying those procedures, this manuscript briefly describes how the rats are trained and used operationally. To date, the rats have performed well and it appears they can play a valuable role in humanitarian demining.
T uberculosis (TB) continues to be a major public health problem especially in developing countri... more T uberculosis (TB) continues to be a major public health problem especially in developing countries. More than 2 billion people (i.e. one third of the world's total population) are infected with TB bacilli (Mycobacterium tuberculosis, the bacteria causing TB). One in every 10 of those people will become sick with active TB in their lifetime. People with HIV/AIDS have more risks of TB infections. Globally, there were 1.77 million deaths from TB in 2007, including 456 000 people infected with HIV, which is nearly 4800 deaths per day 1 . HIV has caused TB incidence to triple in sub-Saharan Africa, where in some countries 80% of TB patients are co-infected with HIV. Thirteen out of the 15 countries with the highest TB burden are in Africa 1 . Despite TB killing more people with HIV than any other disease, in 2008 only 1% of people with HIV had a TB screening. This is a drawback and major challenge to the global efforts towards achieving the TB control targets as well as the UN Mille...
Within the past decade, giant pouched rats have been used successfully to detect landmines. This ... more Within the past decade, giant pouched rats have been used successfully to detect landmines. This manuscript summarizes how these rats are trained and used operationally. The information provided is intended to be of practical value toward strengthening best practices in using Cricetomys for humanitarian purposes while simultaneously ensuring the well-being of those animals.
In recent years, operant discrimination training procedures have been used to teach giant African... more In recent years, operant discrimination training procedures have been used to teach giant African pouched rats to detect tuberculosis (TB) in human sputum samples. This article summarizes how the rats are trained and used operationally, as well as their performance in studies published to date. Available data suggest that pouched rats, which can evaluate many samples quickly, are sufficiently accurate in detecting TB to merit further investigation as a diagnostic tool.
Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To pr... more Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To provide an example of the wide range of problems to which operant conditioning procedures can be applied and to illustrate the common challenges often faced in applying those procedures, this manuscript briefly describes how the rats are trained and used operationally. To date, the rats have performed well and it appears they can play a valuable role in humanitarian demining.
Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are una... more Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are unavailable. In 2014, our pouched rats evaluated sputum from 21,600 Tanzanians and 9,048 Mozambicans whose sputum had previously been evaluated by microscopy, the standard diagnostic for TB. Evaluation by the rats revealed 1,412 new patients with active TB in Tanzania and 645 new patients in Mozambique, increases of 39% and 53%, respectively, when compared to detections by microscopy alone. These results provide further support for the applied use of scent-detecting rats.
This study established evidence about the diagnostic performance of trained giant African pouched... more This study established evidence about the diagnostic performance of trained giant African pouched rats for detecting Mycobacterium tuberculosis in sputum of well-characterised patients with presumptive tuberculosis (TB) in a high-burden setting. The TB detection rats were evaluated using sputum samples of patients with presumptive TB enrolled in two prospective cohort studies in Bagamoyo, Tanzania. The patients were characterised by sputum smear microscopy and culture, including subsequent antigen or molecular confirmation of Mycobacterium tuberculosis, and by clinical data at enrolment and for at least 5-months of follow-up to determine the reference standard. Seven trained giant African pouched rats were used for the detection of TB in the sputum samples after shipment to the APOPO project in Morogoro, Tanzania. Of 469 eligible patients, 109 (23.2%) were culture-positive for Mycobacterium tuberculosis and 128 (27.3%) were non-TB controls with sustained recovery after 5 months without anti-TB treatment. The HIV prevalence was 46%. The area under the receiver operating characteristic curve of the seven rats for the detection of culture-positive pulmonary tuberculosis was 0.72 (95% CI 0.66-0.78). An optimal threshold could be defined at ≥2 indications by rats in either sample with a corresponding sensitivity of 56.9% (95% CI 47.0-66.3), specificity of 80.5% (95% CI 72.5-86.9), positive and negative predictive value of 71.3% (95% CI 60.6-80.5) and 68.7% (95% CI 60.6-76.0), and an accuracy for TB diagnosis of 69.6%. The diagnostic performance was negatively influenced by low burden of bacilli, and independent of the HIV status. Giant African pouched rats have potential for detection of tuberculosis in sputum samples. However, the diagnostic performance characteristics of TB detection rats do not currently meet the requirements for high-priority, rapid sputum-based TB diagnostics as defined by the World Health Organization.
Despite its characteristically low sensitivity, sputum smear microscopy remains the standard for ... more Despite its characteristically low sensitivity, sputum smear microscopy remains the standard for diagnosing tuberculosis (TB) in resource-poor countries. In an attempt to develop an alternative or adjunct to microscopy, researchers have recently examined the ability of pouched rats to detect TB-positive human sputum samples and the microbiological variables that affect their detection. Ten published studies, reviewed herein, suggest that the rats are able to detect the specific odor of Mycobacterium tuberculosis, which causes TB, and can substantially increase new-case detections when used for second-line TB screening following microscopy. Further research is needed to ascertain the rats' ability to detect TB in children and in HIV-positive patients, to detect TB when used for first-line screening, and to be useful in broad-scale applications where cost-effectiveness is a major consideration.
Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To pr... more Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To provide an example of the wide range of problems to which operant conditioning procedures can be applied and to illustrate the common challenges often faced in applying those procedures, this manuscript briefly describes how the rats are trained and used operationally. To date, the rats have performed well and it appears they can play a valuable role in humanitarian demining.
T uberculosis (TB) continues to be a major public health problem especially in developing countri... more T uberculosis (TB) continues to be a major public health problem especially in developing countries. More than 2 billion people (i.e. one third of the world's total population) are infected with TB bacilli (Mycobacterium tuberculosis, the bacteria causing TB). One in every 10 of those people will become sick with active TB in their lifetime. People with HIV/AIDS have more risks of TB infections. Globally, there were 1.77 million deaths from TB in 2007, including 456 000 people infected with HIV, which is nearly 4800 deaths per day 1 . HIV has caused TB incidence to triple in sub-Saharan Africa, where in some countries 80% of TB patients are co-infected with HIV. Thirteen out of the 15 countries with the highest TB burden are in Africa 1 . Despite TB killing more people with HIV than any other disease, in 2008 only 1% of people with HIV had a TB screening. This is a drawback and major challenge to the global efforts towards achieving the TB control targets as well as the UN Mille...
Within the past decade, giant pouched rats have been used successfully to detect landmines. This ... more Within the past decade, giant pouched rats have been used successfully to detect landmines. This manuscript summarizes how these rats are trained and used operationally. The information provided is intended to be of practical value toward strengthening best practices in using Cricetomys for humanitarian purposes while simultaneously ensuring the well-being of those animals.
In recent years, operant discrimination training procedures have been used to teach giant African... more In recent years, operant discrimination training procedures have been used to teach giant African pouched rats to detect tuberculosis (TB) in human sputum samples. This article summarizes how the rats are trained and used operationally, as well as their performance in studies published to date. Available data suggest that pouched rats, which can evaluate many samples quickly, are sufficiently accurate in detecting TB to merit further investigation as a diagnostic tool.
Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To pr... more Giant African pouched rats recently have been used as mine-detection animals in Mozambique. To provide an example of the wide range of problems to which operant conditioning procedures can be applied and to illustrate the common challenges often faced in applying those procedures, this manuscript briefly describes how the rats are trained and used operationally. To date, the rats have performed well and it appears they can play a valuable role in humanitarian demining.
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