Eight-year-old Simon Njeri was in and out of hospital much of last year until his mother, Teresa, went to a drop-in centre in Kayole, Nairobi, run by Women Fighting AIDS in Kenya.

A doctor there quickly diagnosed extra-pulmonary tuberculosis and put Simon first on TB drugs, then on antiretrovirals, for both mother and son are HIV-positive. Six months later Simon was back at school.

Tuberculosis kills two million people worldwide every year, but the standard tools for its detection and treatment fail to reach the majority of sufferers, who are HIV-positive patients, according to the Campaign for Access to Essential Medicines run by humanitarian agency Me’decins Sans Frontie`res (MSF).

The most widely used diagnostic test, the so-called smear sputum, picks up active pulmonary TB but fails to detect extra-pulmonary and latent TB, most frequent among HIV-positive sufferers and children.

As AIDS progresses, patients test TB-negative even though they harbor the bacterium. AIDS also complicates TB clinical diagnosis because opportunistic infections produce similar symptoms.

“Half of our patients have negative smears but keep getting sicker because of TB,” said Gilles van Cutsem, head of an MSF-run TB/AIDS clinic in Khayelitsha township in South Africa - one of the world’s worst countries for the twin TB/AIDS epidemic.

A rate of 250 TB patients per 100,000 inhabitants is considered high-burden. Khayelitsha has 1,500.

LEADING CAUSE OF DEATH

South Africa has the world’s largest number of HIV-positive people - about five million. Two out of 10 people aged 15-49 are infected, according to the United Nations’ HIV/AIDS body, UNAIDS.

Worldwide, 12 million people are co-infected with HIV/AIDS and TB, and two-thirds live in Sub-Saharan Africa.

Although curable, TB is the leading cause of death among HIV-positive people. It appears earlier than other opportunistic infections, advances faster and is fatal if left untreated because undetected.

More sophisticated tests than the 122-year-old smear sputum are used in the West but they are too complex and expensive for poor, TB-endemic countries.

MSF’s Campaign for Access to Essential Medicines urges international partnerships, such as the Bill Gates-funded Foundation for Innovative New Diagnostics, to quickly adapt these tests to poor countries and make them affordable and accessible.

Treatment is a second problem. The worldwide anti-TB strategy, launched in 1994 by the World Health Organisation, is called Directly Observed Treatment Short-course, or DOTS. The campaign argues that DOTS improved over previous disorganized attempts at TB control but fails in the context of AIDS and poverty.

Its cornerstones are the sputum smear test, which is inadequate for AIDS, and treatment, in the form of a daily pill taken for six to eight months.

LIFE DEPENDS ON PILLS

Stopping treatment causes drug resistance. DOTS ensures adherence by direct observation, where a health worker watches the patient pop a pill daily. This is time-consuming and labour-intensive. It implies time and transport costs for the patient. Some find it punitive and demeaning.

It is also unrealistic, experts say.

“There is no way we can do direct observation with these numbers,” van Cutsem said. The clinic treats 1,000 patients and adds 100 new patients every month. “The burden increases but the staff does not,” van Cutsem said.

Moreover, direct observation is inconsistent with antiretroviral treatment, in which patients are taught, then trusted to take daily pills on their own.

“They know their life depends on the pills,” van Cutsem said.

MSF is trying the same approach with TB drugs. So far, compliance is high.

Another advantage of a TB/AIDS clinic is the integration of two services. National TB programs are often run vertically, isolated from AIDS services.

At Khayelitsha, seven out of 10 TB patients are HIV-positive. Treating both diseases in the same clinic simplifies administration and monitoring, and saves people time and effort.

“It is definitely a gain for the patient,” said Marta Darder, Campaign for Access to Essential Medicines coordinator in South Africa.

A third problem is the need for new drugs to treat resistant strains. At least four percent of all cases and more than 10 percent in the former Soviet Union, China, Latvia and Estonia are resistant to first-line drugs. Argentina, Egypt and Mozambique are also developing high resistance.

Second-line drugs are more expensive at $2,500-$3,500 per treatment. They require between 18-24 months of treatment and cure rates are low at 60 percent.

NO NEW DRUGS FOR 30 YEARS

No new TB drugs have been introduced in the last 30 years, according to New York-based Global Alliance for TB Drug Development. It estimates that TB kills one person every 15 seconds and the annual global economic toll is $12 billion.

Scientists at pharmaceutical companies and academic institutions are researching new compounds. Some look promising. Again, the challenge is to speed their development and make them affordable.

Meanwhile, the lethal synergy of TB and AIDS grows. The Global Alliance for TB Drug Development estimates that the number of new TB cases in sub-Saharan Africa will double to four million a year after 2005.

TB treatment is complicated for AIDS patients on life-prolonging antiretrovirals. Drug interaction reduces tolerability and increases cumulative toxicity. Adding more daily pills make compliance harder.

“There is a need for new TB drugs and antiretrovirals that are friendly to use in HIV infected TB patients,” said Paul Nunn, coordinator of the TB/HIV and drug resistance unit of the Stop TB Department and secretary of the TB/HIV Working Group at the World Health Organisation.

WHO recognises DOTS’ limitations in addressing TB in high HIV settings and the need for new, simple and effective diagnostics and drugs.

“More political commitment, scientific interest and resources are needed to hasten these developments,” Nunn said.