Lockdown precipitates huge drop in TB testing

Testing for tuberculosis (TB) at the state laboratory has halved since the start of the lockdown, jeopardising SA efforts to control the disease and putting additional lives at risk.

TB is SA’s leading cause of death, and killed 63 000 people in 2018, according to the World Health Organisation (WHO).

The precipitous decline in TB test volumes at the National Health Laboratory Service (NHLS) is the first hard evidence of disruption to health services caused by Covid-19, which was first detected in SA on March 5.

Less than a fortnight later the government imposed stringent travel restrictions, banned mass gatherings and ordered the closure of schools, swiftly followed by a national lockdown on March 27 that halted most public transport, confined all but essential workers to their homes and brought the economy to a virtual standstill.

SA has so far recorded slightly more than 12,000 cases of Covid-19. By contrast, an estimated 301,000 people fell ill with TB in SA in 2018, according to the WHO.

Nazir Ismail, head of the Centre for TB at the National Institute for Communicable Diseases, said a continued lockdown would unwind the gains SA had made through its investments in combating the disease and lead to a resurgence in TB cases. “The burden of TB has been declining by 5% per annum over the past few years and compared to eight years ago the number of lab confirmed TB cases has almost halved,” he said.

“Modelling work conducted by WHO suggests that if the Covid-19 pandemic led to a global reduction of 25% in expected TB detection for 3 months — a realistic possibility given the levels of disruption in TB services being observed in multiple countries — then we could expect a 13% increase in TB deaths,” said Ismail.

Ismail attributed the drop in TB testing at the NHLS, which does 95% of SA's TB tests, to the reduction in public transport to clinics, patients delaying seeking care, and neglect of TB screening during the lockdown. The laboratory's TB testing capacity had been unaffected by its well-publicised Covid-19 test backlog, he said.

He co-authored an analysis of NHLS TB testing data, which compared volumes before and after the government implemented measures to curb transmission of Covid-19. In the six weeks before the government intervened, the NHLS conducted an average of 47,520 tests a week. In the five weeks after the lockdown began, it performed an average of 24,574 tests per week, a 48% decline.

The analysis found a less dramatic fall in the average weekly number of TB cases detected before and after the lockdown, suggesting people were getting tested when they were sicker. The average number of positive tests per week fell from 3,710 before the interventions to 2,473 afterwards, a 33% decline.

“TB disease is a spectrum and those with mild but infectious TB will likely delay care until they need more advanced care, which would worsen outcomes and also consume hospital bed capacity,” said Ismail.

kahnt@businesslive.co.za