Wellness & Fitness

Tackling ‘silent’ killer tuberculosis

TB

Medical illustration of the symptoms of tuberculosis. PHOTO | FOTOSEARCH

A lot has been done to sensitise people on the classical symptoms of tuberculosis (TB) such as persistent coughs, chest pains and fatigue.

This type of tuberculosis, known as Active TB, comes with noticeable signs that can alert affected people that something is wrong, hence making them seek medical attention.

But not much is understood about another type of the condition known as Latent or “silent TB”, which comes with no symptoms and can thus be ignored for a long time.

In Active TB, large numbers of the TB bacteria (Mycobacterium tuberculosis) get into the body.

They then grow for some time before becoming active and attacking the body, leading to symptoms of the disease which make people sick and at risk of death if they are not treated. They also become infectious hence being able to spread the deadly disease to others.

With Latent TB, the opposite happens. In this case, the TB bacteria — in small numbers — get into the body.But before they get time to grow and make people sick, the immune system overpowers them, rendering them inactive.

The bacteria can stay in this state of inactivity for many years without causing any harm. As such, carriers may not even be aware that they have them in their bodies. And in this state, they cannot spread the TB bacteria to other people.

Low immunity

Nevertheless, during this period of inactivity, the bacteria never relax. They stay in wait for the perfect opportunity, when the immunity is low to rear their heads and strike hard, causing Active TB that makes people sick.

This was the case with Mary Otieno from Homa Bay County. Her health was okay for many years until she was diagnosed with Type 2 diabetes, which made her ill and sickly for years.

During this period of indisposition, she was diagnosed with TB even though she had not had recent contact with someone with the disease. She eventually recovered albeit going through so much grief and suffering.

“I didn't know I was carrying the bacteria in my body all along. If I knew, I would have been tested and treated to avoid all these challenges.”

As countries focus on the more lethal Active TB, the World Health Organisation (WHO) is urging them to also pay attention on Latent TB for effective disease prevention.

Based on results of the 2016 Kenya Tuberculosis Prevalence Survey, close to 140,000 (138,105) people fall sick each year with ActiveTB.

Dr Maureen Kamene, head of the National Tuberculosis and Lung Disease Programme (NTLD) notes that in high burden TB countries like Kenya, many people are carriers of Latent TB. "We need to catch the condition early and treat it before it makes people sick. This will bring down the cases of Active TB in the country,” said Dr Kamene.

The Ministry of Health (MOH) has for a long time only targeted at risk populations for screening and treatment of the condition. They include people living with HIV and children below the age of five years that are in contact with individuals infected with TB.

Screening

“Due to their low immunity, they are likely to develop Active TB if they are carriers of Latent TB. So to prevent that from happening, we need to screen them and treat the condition,” said Dr Brenda Mungai, the Chief of Party for the Tuberculosis Accelerated Response and Care (TB-ARC) at the Centre for Health Solutions (CHS).

“Generally, if your immunity is likely to be low for one reason or another, then it's important to screen for Latent TB."

In a bid to further enhance the fight against TB, plans are underway to widen the scope of latent TB screening and treatment.

“We will begin with health workers and prisoners before moving to the wider population,” Dr Kamene says. “

Other high risk groups that can be targeted for Latent TB screening and treatment include people receiving dialysis, those preparing for organ transplants as well as people with non-communicable diseases like cancer and diabetes as their immunity is usually low.

“Generally if your immunity is likely to be low for one reason or another, then you are the target population.

To screen for Latent TB, two tests can be used. They include the Tuberculin Skin Test (TBT) - also known as Mantoux test - as well as the Interferon Gamma Release Assays (IGRA) blood test. During the skin test, the doctor uses a small needle to inject some harmless fluid called tuberculin under the skin on someone's arm.

WHO guidelines

The arm is then checked or assessed in two or three days. The presence of an induration or swelling (raised, palpable hardened area) at the site of the injection with the recommended diameter measurements - based on the WHO guidelines - is considered a positive test. If blisters are present (vesiculation), the test is also considered positive.

The IGRA test on the other hand, can help in detecting latent TB by measuring a person's immune reaction to the tuberculosis bacteria.

Those who test positive for Latent TB are usually treated with Isoniazid or INH, which has to be taken daily for six to nine months.

Dr Kamene notes that Kenya plans to roll out a new drug for the condition known as 3HP (rifapentine combined with isoniazid) that will offer a shorter three-month dose for those affected.

"The drug will be taken once a week for 12 weeks. So it will definitely help with adherence."