Latent TB: a time bomb among people living with HIV in Kenya

On World TB Day, Lucy Maroncha asks why people living with HIV in Kenya are not being offered effective diagnostic tests which mean they could receive early treatment on tuberculosis.

World TB Day (24 March) highlights the need to reach, treat and cure everyone who has the disease. So why are people living with HIV in Kenya, who could also have latent tuberculosis, not offered effective diagnostic tests which mean they can receive early treatment?

For people living with HIV, tuberculosis (TB) is the most common opportunistic infection and a major cause of death. Early detection of the disease while it is still latent is the most effective way to combat it. Although there is a test for latent TB – the tuberculin skin test – in Kenya it is not widely used and latent TB in people living with HIV is rarely addressed until it develops into active TB.

Latent TB is where a patient is infected with mycobacterium tuberculosis but the bacteria is inactive. According to World Health Organization (WHO) guidelines, ten percent of people with latent TB develop active TB in their lifetime, with the majority developing it within the five years of their initial infection. In people living with HIV, this can happen sooner than five years, because of their compromised immunity.

According to Jeremiah Chakaya, physician and CEO of Kenya Association for the Prevention of Tuberculosis and Lung Disease, people living with HIV should be tested for latent TB, because those who test positive can be put on isoniazid preventive therapy (IPT), which can prevent the development of active TB. This treatment is offered at no cost in health facilities, but many people are missing out because they don’t know they have latent TB.

Tests fail to detect TB

In Kenya, the chest X-ray and the sputum test are the most common methods to test for TB. But, as these tests don’t detect latent TB, it is possible for a person living with HIV to unknowingly have a co-infection of latent TB. This can erupt into active TB at any time due to the low immunity of the patient.

Sue*, 30, who is living with HIV, had complained of fatigue and a heavy chest to her doctor for six months.She had a chest X-ray and sputum tests to try and establish if these symptoms were caused by TB, but the tests were negative. Sue then decided to pay for the tuberculin skin test, as it was not offered at her local health facility.

“When I was taken to one of the best equipped hospitals in Nairobi, and I had the tuberculin skin test done, it showed that I had TB,” she says. Sue is concerned that there are hundreds of people living with HIV who can’t afford such medical facilities and do not know they have latent TB. “Sadly, this bacterium may one day take them by surprise when it explodes into active TB,” she observes.

Evaline Kibuchi, senior TB manager at the Kenya AIDS NGOs Consortium (KANCO), says that every person is exposed to the bacteria that causes latent TB. She stresses that it is imperative for people living with HIV to have regular TB check-ups in order for them to seek treatment at the slightest symptoms of active TB. She says: “Our main campaign is to educate people living with HIV to understand TB as a disease and to urgently address any symptoms with their health provider. People who already know they have HIV should be responsible and observe such factors as good nutrition, medication adherence and contact tracing, to establish how often they have been exposed to TB.”

Lack of regular screening

The number of TB-associated deaths among people living with HIV has decreased from 540,000 in 2013 to 360,000 in 2014. But, as the WHO Global Tuberculosis Report 2014 indicates, preventive measures and early TB detection still need scaling up. Regular TB screening for people living with HIV is not often conducted in HIV facilities. Some patients do not detect symptoms of TB in their bodies and, if they do, they attribute them to the fact that they have HIV.

Lucitta Mogaka, 53, has lived with HIV for over 15 years and says that since she was treated for TB ten years ago her doctor has never suggested another screening. She explains how she almost missed a trip out of the country when the embassy asked her for a tuberculin skin test due to her prior TB infection. “I didn’t know that such a test existed and I was very scared because had it tested positive, I would have been put on two months TB medication before getting the visa,” she says.

Dr Immaculate Kathure, child TB services coordinator for the National TB Program, says the tuberculin skin test is not widely available because latent TB is not infectious and is not treated. “The test is used only if the TB diagnosis is not clear and there’s need to check if the person suspected to have TB has been exposed,” she says. She adds that there are newer diagnostic tests with better sensitivity such as GeneXpert, which are now widely available but patients have to pay for them.

Many people living with HIV, especially in rural areas, either do not know about these tests or cannot afford the cost. And it is evident that though the mycobacterium is inactive, it’s only a matter of time before it turns into active TB in a body whose immunity is already at risk. As World TB Day approaches, bringing such tests as the tuberculin test and GeneXpert to local HIV health facilities and offered at no cost to people living with HIV would be a big leap towards scaling up early TB detection.

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