WHO publishes LSTM-led cross-sectional survey on drug resistance of TB in Malawi

The online research section of the Bulletin of the World Health Organization (WHO) published the results of a cross-sectional survey aiming to document the prevalence of multidrug resistance among people newly diagnosed with, and those retreated for, tuberculosis (TB) in Malawi. The survey, led by the Malawian national TB programme, the Liverpool School of Tropical Medicine (LSTM) hosted Centre for Applied Health Research & Delivery (CAHRD), Management Sciences for Health's (MSH) USAID-funded Tuberculosis Control Assistance Programme (TB CAP)  and in cooperation with WHO, found that the prevalence of multidrug resistance among people with smear-positive TB was low for sub-Saharan Africa – probably reflecting the strength of Malawi’s TB control programme. The relatively high prevalence of such resistance observed among those with previous treatment failure may highlight a need for a change in the national policy for retreating this subgroup of people with TB.

Although the World Health Organization (WHO) has monitored the emergence of drug resistance in Mycobacterium tuberculosis since 1994, there have been few national surveys of such resistance in sub-Saharan Africa. 

In 2012 it was estimated that about 1.9% of people newly diagnosed and 9.4% of those undergoing retreatment in Africa had multidrug-resistant tuberculosis (MDR TB). Back in 2007 the nationally recommended treatment regimen for people newly diagnosed with TB in Malawi changed. Four problems with this change were identified that need monitoring: poor adherence risking MDR TB; the impact of second-line drugs that were routinely used in Malawi since 2007; high prevalence of HIV infection among people with TB and the impact of migration into Malawi from neighbouring countries with MDR TB outbreaks. As a result a national survey of resistance to anti-tuberculosis drugs in Malawi was conducted. 

The authors, using WHO approved methodologies, engaged all of Malawi’s 48 TB registration centres and undertook a prospective, cross-sectional survey by grouping these centres into three zones for phased sample collection. ‘The outcome was that the prevalence of MDR TB is currently low in Malawi: 0.4% of new TB cases and 4.8% of retreatment cases – probably as the result of a strong TB control programme – whereas HIV-coinfection, which has been associated with high mortality in the presence of drug-resistant TB, is common’, said senior author and LSTM Professor Bertie Squire.

Based on the survey outcomes the authors recommend changes to Malawi’s current MDR tuberculosis treatment regimen as well as a repeat of the survey within three years to monitor the impact of the increasing prevalence of drug resistance in some neighbouring countries and the recent introduction of unsupervised rifampicin into TB treatment regimens in Malawi.