In 2013, 550,000 children were estimated to be infected worldwide, according to the World Health Organization.
"Children are expected to contribute to between 12-20% of our TB cases ... that's about 12,000 children," says Frank Mugabe, national TB program manager for the Ministry of Health in Uganda, where more than 60,000 new cases of TB are diagnosed each year. Uganda is one of the 22 high-burden TB countries globally and weakened immunity due to high rates of HIV in the population further exacerbates the occurrence of TB.
TB is a complicated disease with the potential to affect many parts of the body and it can remain latent in people for many years, leaving them unaware they are infected. The main active form of the disease affects the lungs; if left untreated it can cause considerable lung damage, resulting in eventual death. But the disease is curable.
Standard tests for TB struggle to detect infections in children, often causing them to be diagnosed either too late, or not at all. "Most of the children have to be diagnosed clinically ... so they're among the missed cases," says Mugabe.
Finding the disease
"The challenge remains getting these children at the right time with diagnosis," says Dr. Hondimagegnehu Alemu, Uganda's country representative for the World Health Organization.
The main method of diagnosing TB is by testing samples of mucus -- known as sputum -- coughed up by patients suspected to be infected. Testers search for the presence of the bacteria behind the disease -- mycobacterium tuberculosis -- in these samples, to identify those infected. But children cannot produce much sputum, and when they can cough-up, fewer bacteria are usually lurking within, making them a further a challenge to diagnose.
This was the case for six-year-old Bukenya Hethiri, diagnosed with TB in 2014. He lives with his mother in a slum in the Kawempe division of Kampala, where mud streets, dense housing and poor access to sewage systems encompass his daily life. Poor ventilation in many slum houses means children are easily exposed to airborne infections such as TB. "By the time they are five years most of them have been exposed to TB," says Alem.
Hethiri had been coughing for more than three years. Despite various visits to healthcare services and even resorting to local traditional healers, he remained undiagnosed -- until one day a voice came shouting in the distance.
The voice was that of a local village health team member, part of the SPARK TB program, a partnership of public and private healthcare facilities in Kampala coordinated by the International Union of Lung Disease and Tuberculosis
As part of SPARK-TB, village health teams and monthly health camps at marketplaces are helping to spread information about the signs and symptoms of TB within the communities at most risk.
"We have one health camp per month for every administrative division," says Dr. Anna Nakanwagi, country director for the International Union.
The objective is to also overcome the lack of skills and equipment to diagnose TB in the 1,000 or more private healthcare clinics estimated to practice in Kampala, which, due to their size and proximity, are the first port of call for more than 50% of the population in Kampala. But infections are often diagnosed wrongly, or not at all.
"If you went to a private health facility ... you should [expect] to be able to find somebody who has capacity to diagnose TB," says Nakanwagi.
The 70 clinics in the first round of the program were provided with access to "Gene Xpert" machines, which enable rapid diagnosis of TB samples within a few hours, and with improved accuracy. The more recent Spark TBPlus program -- initiated in 2014 -- has expanded to equip 208 clinics in Kampala and its surrounding districts. Fourteen of the clinics have benefited from sputum induction machines, where a nebulizer and tubing is used to stimulate sputum production within a child's larynx to then suck it up for sampling.
"So far we have tested 10 children with sputum induction," says Dr. Drake Kizito, director of the Doctors Medicare clinic in Mukono, near Kampala, whose clinic staff were trained in sputum induction six months ago. The medicare clinic lies in a quiet peri-urban area where only mild traffic passes by on its orange mud streets.
Thirty patients attend the clinic on an average each day, paying 10,000 Ugandan shillings ($3) on average to see a doctor to be diagnosed, but treatment is then free. Of the 10 sputum inductions Kizito has performed, only one was diagnosed with TB. "[But] the community we are in is so crowded," he says. "I think we can find more numbers."
Out of the lungs
Another factor complicating diagnosis is that while TB usually affects the lungs, children are more likely than adults to develop a form of the disease known as extra-pulmonary TB, in which other organs become infected. This can cause a diverse range of symptoms that are easily missed as being TB and are again hard to diagnose as they require biopsies or radiological scans to search for specific signs of infection.
"Around 30% of TB in children is extra-pulmonary," says Alem. "[But] they are not infectious -- they don't have the ability to transmit to other people." Transmission of the disease is airborne, commonly through the cough of someone infected.
This lack of infectiousness alongside the reduced infectiousness of children with the standard pulmonary form of TB has meant they have not been prioritized by public health teams, fueling a hidden epidemic not just in the urban poor in Kampala, but globally.
But things are changing.
"Of late we are prioritizing all forms of TB," says Mugabe, who is also now coordinating national TB prevalence surveys across Uganda to get a more detailed insight into the country's epidemic.
This once invisible subset of the population is now entering the spotlight, in Uganda at least.