More than half a million children who fall ill with tuberculosis each year are at risk of dying because of a lack of child-friendly treatments, experts said.

Tuberculosis, which kills more than one person every 20 seconds, is much harder to detect in children than in adults because they do not always show the typical symptoms, such as coughing, night sweats and blood in the phlegm or spit.

As a result, health workers tend to focus on treating adults displaying symptoms of the potentially deadly air-borne disease, experts said. But, if left untreated, children with TB become ill and die much faster than adults.

"A huge number of children are suffering and dying from TB because the majority of efforts to fight the disease have focused on adults, so children with TB have become invisible," said Mercedes Becerra, an associate professor at Harvard Medical School in Boston, United States.

"And even if they get treatment, we lack reliable diagnostic tools and child-friendly medicines, which hinders effective treatment and can even fuel drug resistance," she told the Thomson Reuters Foundation in a telephone interview.

TB, which kills at least 80,000 children each year, is a contagious bacterial lung illness that spreads via the coughs and sneezes of an infected person.

It is hard to treat, requiring months of antibiotic treatment, and drug resistant strains are rapidly gaining a foothold.

SLOW PROGRESS

Five years ago the WHO recommended new and more appropriate doses for childhood TB but pills for children have yet to be manufactured.

Instead, doctors and parents have to crush or split adult pills, which often leads to the wrong doses, potentially fuelling a growing number of drug-resistant cases that no longer respond to the most commonly used treatments for TB, experts said.

As many as 32,000 children become sick with multi-drug resistant strain of TB (MDR-TB) each year, according to a study last year co-authored by Becerra, forcing them to take a daily cocktail of drugs with heavy side effects for up to two years.

"Even if children get ill with MDR-TB, they respond well if they get treatment," said Becerra. "(Not treating them) is a huge missed opportunity - if you treat them, you can cure them."

Shelly Malhotra, director of market access at the TB Alliance, said progress in creating child-friendly TB drugs had been slow but that three pharmaceutical companies were currently seeking approval from the WHO to produce such formulations.

The New York-based TB Alliance, which is dedicated to the discovery and development of new, faster-acting and affordable TB medicines, is hoping to make them available through its Global Drug Facility in the second half of this year, she said.

The lack of child-friendly formulations is part of a wider malaise in finding new TB drugs, an issue that has become more pressing due to drug resistance.

Even though TB is the world's second largest infectious disease, there have been no new drugs for almost 50 years and new ones developed recently are still undergoing trials.

LACK OF DATA

Manufacturers have been slow to respond to the challenge of finding child-friendly TB drugs partly because a lack of accurate data makes it hard for them to gauge the size of their potential market, Malhotra said.

"There is a lack of accurate data in many countries, in particular where there is a large private treatment sector, so we don't get good data from villages, from the private providers, or even hospitals," Malhotra told the Thomson Reuters Foundation.

Every childhood TB case should be registered with the national TB control program, including crucial data such as age, HIV status and treatment outcome, she said.

Becerra urged governments and donors to provide more funding so that health workers could get better training to make sure they do not miss children with TB.

Simple steps, such as making sure that children of TB patients are tested for the disease, can go a long way to improve the situation, said Becerra.

"TB is a family disease, a social disease, so that's where it needs to be tackled - at the household level through contact-tracing," she said.

"It's a fundamental part of what Europe and the U.S. have done for a long time but it's still not done consistently in the developing world due to lack of resources."