Browsing by Author "Ellis, H."

Now showing 1 - 2 of 2

Accuracy of giant African pouched rats for diagnosing tuberculosis: comparison with culture and Xpert W MTB/RIF
(Researchgate, 2017) Mulder, C.; Mgode, G. F.; Ellis, H.; Valverde, E.; Beyene, N.; Cox, C.; Reid, S. E.; Van’t Hoog, A. H.; Edwards, T. L.
S E T T I N G : Enhanced tuberculosis (TB) case finding using detection rats in Tanzania. O B J E C T I V E S : To assess the diagnostic accuracy of detection rats compared with culture and Xpert w MTB/ RIF, and to compare enhanced case-finding algorithms using rats in smear-negative presumptive TB patients. D E S I G N : A fully paired diagnostic accuracy study in which sputum of new adult presumptive TB patients in Tanzania was tested using smear microscopy, 11 detection rats, culture and Xpert. R E S U LT S : Of 771 eligible participants, 345 (45%) were culture-positive for Mycobacterium tuberculosis, and 264 (34%) were human immunodeficiency virus (HIV) positive. The sensitivity of the detection rats was up to 75.1% (95%CI 70.1–79.5) when compared with cul- ture, and up to 81.8% (95%CI 76.0–86.5) when compared with Xpert, which was statistically signifi- cantly higher than the sensitivity of smear microscopy. Corresponding specificity was 40.6% (95%CI 35.9– 45.5) compared with culture. The accuracy of rat detection was independent of HIV status. Using rats for triage, followed by Xpert, would result in a statistically higher yield than rats followed by light- emitting diode fluorescence microscopy, whereas the number of false-positives would be significantly lower than when using Xpert alone. C O N C L U S I O N : Although detection rats did not meet the accuracy criteria as standalone diagnostic or triage testing for presumptive TB, they have additive value as a triage test for enhanced case finding among smear- negative TB patients if more advanced diagnostics are not available
Tuberculosis detection by pouched rats: Opportunities for reinforcement under low-prevalence conditions
(2017 Elsevier B.V, 2017) Edwards, T. L.; Ellis, H.; Watkins, E. E.; Mulder, C.; Mgode, G.; Cox, C.; Poling, A.
Giant African pouched rats (Cricetomys ansorgei) have been employed successfully in two operational tuberculosis-detection projects in which they sniff sputum samples from symptomatic individuals who have visited tuberculosis clinics. The prevalence of pulmonary tuberculosis in this population is high, approximately 20% in the regions where the rats have been used. If the rats are to be used to screen individuals from lower- prevalence populations, their performance under such conditions must first be evaluated. In this study, the prevalence of tuberculosis-positive samples presented to eight pouched rats was reduced to approximately 5%, and the percentage of known-positive samples included as opportunities for reinforcement was varied in sequence from 10 to 8, 6, 4, 2, 4, and 2. Liquid food reinforcers were delivered for identification responses to known-positive samples and at no other time. The rats’ accuracy was clinically and statistically significantly lower at 2% than at the other values. These results indicate that the rats can perform well in low-prevalence scenarios but, if they are used under the conditions of the present study, at least 4% of the samples presented to them must be opportunities for reinforcement.