![]() Weeks or months are required to detect mycobacterial drug resistance through the culture and drug-susceptibility testing methods commonly available in the region ( 6). Dashed lines indicate a strategy of early outpatient screening among detected TB cases for XDR TB and potential community-based XDR therapy. Proportion z of the population is also infected with non-XDR TB strains. ![]() Persons can be uninfected with XDR TB (S), latently-infected (L long latency E, brief latency), actively infected and not yet detected (U, undetected for TB generally I, detected for TB but placed on empirical first-line therapy before drug-susceptibility testing X, queueing for drug-susceptibility testing as a result of having suspected XDR D, defaulted from the testing and treatment system), identified as XDR and initiated on XDR therapy ( T h reflecting inpatient XDR therapy T c reflecting potential community-based XDR therapy programs), or recovered after therapy (R, among a proportion for whom XDR therapy is potentially effective). ![]() The model equations are detailed in SI Appendix. Health states are further stratified by HIV and antiretroviral therapy status, and mortality is subtracted from all compartments. Admission and discharge are symbolized by gray arrows. Non-XDR patients can be admitted to the ward for other TB disease, and risk superinfection/nosocomial infection. Subscripts “c” and “h” refer to the community and hospital environments, respectively (separated by a dotted vertical line). ![]() The KwaZulu-Natal province has reported the highest number of cases to date. ( A) Reported XDR TB cases in South Africa, by province, from January 2004 to March 2007. Using branching process mathematics, we observed that early, community-based drug-susceptibility testing and effective XDR therapy could help curtail ongoing transmission and reduce the probability of XDR TB epidemics in neighboring territories.īurden and dynamics of XDR TB. In the setting of delayed disease presentation and high system demand, improved diagnostic approaches may need to be employed in community-based programs rather than exclusively at tertiary hospitals. Intensified community-based case finding and therapy appears critical to curtailing transmission. The effective reproductive number of XDR TB in KwaZulu-Natal may be around 2. ![]() We analyzed the transmission dynamics of XDR TB in the region using mathematical models, and observed that nosocomial transmission clusters of XDR TB may emerge into community-based epidemics under the public health conditions of many South African communities. Extensively drug-resistant tuberculosis (XDR TB) has been detected in most provinces of South Africa, particularly in the KwaZulu-Natal province where several hundred cases have been reported since 2004. ![]()
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