Monday March 24 2014

Why controlling tuberculosis has remained difficult in Uganda

By Agatha Ayebazibwe

Today is World Tuberculosis (TB) Day. Uganda joins the rest of the world to commemorate the day and highlight this public health problem that has seen the country remain in the 14th position among 22 countries with the highest disease burden globally.

According to statistics from the World Health Organisation, an estimated 60,000 new infections of the disease occur every year. However, 31 per cent of these are not diagnosed and therefore not treated. This trend, according to experts, waters down the efforts to control the disease among populations.
Dr Alphonse Okwera, the Head of the National TB referral Treatment Centre at Mulago Hospital, says that the undiagnosed cases have negative implications ranging from continuous transmission, advanced disease presentation and a higher risk of developing multi drug resistant TB.

“A case of open TB in the community infects 15 to 20 people in the community. This means that for every one case that is diagnosed at a health facility, another 10 to 20 has already been infected. This makes the control of the disease very difficult,” says Dr Okwera.

The head of the TB and Leprosy Programme at the Ministry of Health Dr Frank Mugabe, on the other hand, says the missed cases are responsible for the biggest percentage of new infections that are registered at different facilities annually.
“If we can design programmes that will target all the people with TB infection, treat, and cure them, we will have gone an extra mile to eradicate the disease that is affecting mostly poor people,” Dr Mugabi says.

Why the missed cases
The current method used for testing of TB in Uganda has been faulted and said to be the number one reason behind the big number of undiagnosed cases of TB. In fact, the smear microscopy procedure – which involves collecting a sputum sample, then viewing the TB bacterium through a microscope glass can only detect a maximum of 50 per cent of all TB cases leaving another 50 per cent undetected.
This, according to Dr Lydia Nakiyingi, a TB Investigator in the area of diagnostic research at the Infectious Disease Institute, has resulted in delayed diagnosis, delayed treatment and in such circumstances, the disease progresses leading to death, majority of such deaths occurring in HIV infected people.

“In fact, if you go to a low level health facility, where the only mode of testing is using a smear microscopy, 50 per cent chances are such that you will not be given the right diagnosis. In scenarios where a person who has the disease and it has not been detected, when they go back to the community, they transmit to others and their disease progresses until they present with signs and symptoms,” she notes.
Majority of missed cases happen among the children below seven years, and HIV infected people, according to researcher Dr Nakiyingi. And this is because children do not produce enough sputum that can be relied on to make conclusive diagnosis.
“Diagnosing TB in a child of less than seven years is very difficult in settings like ours where we rely on sputum samples. Children don’t know how to cough out and when they do, the sample is usually not adequate,” says Mugabi.

Under such circumstances, the health worker has to go an extra mile to look out for clinical signs, look out for the history including possible contact with the infected person, as well as do X-ray and Ultra sound scans. Unfortunately, Dr Okware says that these are not available at lower health facilities.
And in the cases of HIV positive individuals, the already lowered immunity contributes a lot to the development of TB but also affects its diagnosis especially among patients who have advanced HIV. In Uganda, half of the TB patients are HIV positive.

Dr Nakiyingi says majority of the HIV positive TB patients lack adequate sputum sample but also changes the manifestation of TB.
“Ideally, the TB bacterium is supposed to collect in one pocket-like cup so that when a patient coughs, it all comes out but with HIV, the TB goes to different parts of the body making what comes out so inadequate that it cannot be relied on.”
In most cases, as the experts say, the amount of sputum that comes out tests negative. Dr Nakiyinji says that even when the tests don’t confirm the disease, the patient, if not treated will continue wasting away as well as transmitting the disease to those he gets in contact with. “And this is the real challenge in the fight of Tuberculosis,”

She further says that extra pulmonary Tuberculosis also contributes to the increasing number of missed cases. Extra pulmonary TB is that where the infection spreads beyond the lungs causing other types of TB whose diagnosis is very difficult in Uganda because the system lacks capacity to diagnose it – at least if what the TB Programme manager says is anything to go by. This type of TB affects 15–20 per cent of all TB cases and occurs more commonly in immunosuppressed persons and young children.

“In those with HIV, this occurs in more than 50 per cent of the cases” says Mugabe.
The TB caused by extra pulmonary TB includes the pleura called tuberculosis pleurisy, the central nervous system or tuberculosis, TB meningitis, TB of the lymphatic system, Spine TB, Heart TB, skin TB and abdominal TB.

Measures being put in place to address the problem
The World Health Organisation in 2010 recommended that the test – the Gene Xpert machine should be used as the initial diagnosis test in individuals suspected of having MDR TB, or HIV associated TB. They also suggested that it could be used as a follow-up test to microscopy in settings where Multi Drug Resistant TB and HIV is a bigger concern because of the lack of accuracy of smear microscopy.
In Uganda, the machines were introduced last year and so far 19 centres across the country are using it to test for TB. Dr Okwera says the test is more reliable when compared to sputum microscopy and the speed of getting the result when compared with the previous test methods.

“For diagnosis of TB, although sputum microscopy is both quick and cheap, it is often unreliable. It is particularly unreliable when people are HIV positive. And while the culture gives a definitive diagnosis, to get the result usually takes weeks rather than the hours of the Xpert test.” He says there is need for more of these machines to cater for at least each district.
“Integrating TB and HIV programmes is another promising strategy because we are able to trace most of the TB infections among HIV positive people,” says Dr Nakiyingi.

Under this strategy, every HIV positive individual is screened for TB when they visit centres for HIV services. Those who are found to be TB positive are initiated on TB treatment. “This has helped in having as many patients with both HIV and TB on treatment to boost their immunity. This is very important because TB kills majority of the Aids patients if they are not treated early.”