Almost 65% of Africans Don't Show Typical Signs of TB Which Means Disease Can Spread Silently

A total of 63.7% of Africans don't have any cough while being ill with tuberculosis (TB), a recent study done by researchers from the University of Cape Town and Amsterdam University Medical Center (UMC) showed.

The meta-analysis examined the outcomes of national monitoring programs in eight African countries (The Gambia, Ghana, Lesotho, Nigeria, South Africa, Sudan, Uganda, and Zambia) and four Asian countries that included 602,863 people in total. It showed that 82.8% of the population in the regions are carrying undetected TB, showing no persistent cough while 62.5% had no cough at all. This makes it easier for the disease to spread and poses substantial challenges for attempts to control TB.

Among the African countries participating in the study, Sudan had the largest percentage of people not experiencing a cough — 14.8%, or 73,568 people.

The research also discovered that over 25% of individuals with tuberculosis had no other symptoms, in addition to the absence of a cough. Both of these features are more prevalent in women than in men. Additionally, the study revealed that a quarter of individuals who do not have a cough exhibit significant amounts of bacteria in their sputum, indicating a high likelihood of being extremely contagious.

The scientists expressed concern over the fact that such a large proportion of patients with TB do not show a chronic cough, that so far has been regarded as the most prevalent indication of this infectious disease.

"We estimated that, overall, up to 83% of adults in the community with culture-confirmed tuberculosis report no cough persisting for two or more weeks, up to 63% report no cough of any duration, and (based on a subset of surveys) up to 28% report no tuberculosis-suggestive symptoms (i.e., cough, fever, chest pain, night sweats, or weight loss) at all," the study read.

This study allowed a fresh look at the problem of diagnosing and spreading tuberculosis because it has become clear that a patient may not necessarily show all the typical symptoms of the disease but nevertheless be infectious, which is dangerous both for the sick person and for those around him.

"Our results indicate the probable reason why, despite huge efforts to diagnose and treat the disease, the TB burden across Africa and Asia is hardly declining [...]," Frank Cobelens, Professor of Global Health at Amsterdam UMC, was quoted as saying. "A persistent cough is often the entry point for a diagnosis, but if 80% of those with TB don't have one, then it means that a diagnosis will happen later, possibly after the infection has already been transmitted to many others, or not at all."

He added that the medical community needs to "really rethink" the way tuberculosis should be diagnosed.

"When we take all of these factors into account, it becomes clear that we need to really rethink large aspects of how we identify people with TB. It's clear that current practice, especially in the most resource-poor settings, will miss large numbers of patients with TB. We should instead focus on X-ray screening and the development of new inexpensive and easy-to-use tests," Cobelens said, as cited by the Amsterdam UMC.

According to the World Health Organization (WHO), TB affects 10 million people annually. Approximately 50% of tuberculosis cases are concentrated in eight countries: Bangladesh, China, India, Indonesia, Nigeria, Pakistan, Philippines, and South Africa.

It is estimated that around a quarter of the world's population is infected with tuberculosis bacteria, yet the majority of people will not develop the disease, and some will clear the infection. Those who are infected but not yet ill cannot spread the disease.

In 2022, a total of 2.5 million individuals in the African region contracted tuberculosis, which represents 25% of all new tuberculosis cases globally. An estimated 424,000 people died from the disease that year. The WHO also stated that over 33% of TB deaths occur on the continent.