CROI: Urgent action needed to avert `catastrophic` drug-resistant TB epidemic

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Six hundred million dollars a year for the next decade will be needed to avert a catastrophic global epidemic of drug-resistant tuberculosis (TB), World Health Organization (WHO) TB expert Paul Nunn told the opening day of the Fourteenth Conference on Retroviruses and Opportunistic Infections (CROI) in Los Angeles. WHO estimates that 27,000 cases of extensively drug-resistant (XDR) TB are occurring worldwide each year, but that number could escalate, he warned the conference.

XDR TB was first identified as a global threat in March 2006, when WHO and the US Centers for Disease Control published details of TB cases resistant to isoniazid, rifampicin, all the fluoroquinolone TB drugs and at least one of the injectable drugs used to treat multi-drug resistant TB.

In August 2006 South African researchers reported that an outbreak of XDR TB at a rural hospital in Kwazulu Natal had killed over 50 people within a month of diagnosis, and within weeks cases of XDR TB were being identified all over South Africa.

Glossary

extensively drug-resistant TB (XDR-TB)

A form of drug-resistant tuberculosis in which bacteria are resistant to isoniazid and rifampicin, the two most powerful anti-TB drugs, plus any fluoroquinolone and at least one injectable second-line drug. 

multidrug-resistant tuberculosis (MDR-TB)

A specific form of drug-resistant TB, due to bacilli resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs. MDR-TB usually occurs when treatment is interrupted, thus allowing organisms in which mutations for drug resistance have occurred to proliferate.

opportunistic infection (OI)

An infection that occurs more frequently or is more severe in people with weakened immune systems, such as people with low CD4 counts, than in people with healthy immune systems. Opportunistic infections common in people with advanced HIV disease include Pneumocystis jiroveci pneumonia; Kaposi sarcoma; cryptosporidiosis; histoplasmosis; other parasitic, viral, and fungal infections; and some types of cancer. 

infection control

Infection prevention and control (IPC) aims to prevent or stop the spread of infections in healthcare settings. Standard precautions include hand hygiene, using personal protective equipment, safe handling and disposal of sharp objects (relevant for HIV and other blood-borne viruses), safe handling and disposal of waste, and spillage management.

isoniazid

An antibiotic that works by stopping the growth of bacteria. It is used with other medications to treat active tuberculosis (TB) infections, and on its own to prevent active TB in people who may be infected with the bacteria without showing any symptoms (latent TB). 

Dr Karin Weyer of the South African Medical Research Council told the conference that 106 cases of XDR TB have now been reported from Tugela Ferry, the site of the original outbreak.

The MRC estimates that based on a 10% failure rate for MDR TB treatment in South Africa, the country could already be facing 600 cases of XDR TB each year. Experience from Latvia shows that even with a relatively well resourced TB treatment infrastructure and a low HIV prevalence, only 27% of cases of XDR TB identified were cured, Paul Nunn reported. Virtually all the others died.

Paul Nunn condemned recent calls for quarantine to be given a greater role in the control of XDR TB.

“Calls for quarantine are premature and not useful. There first has to be an effective management system in place for drug-resistant TB,” he said.

Highlighting the severe shortage of qualified health care workers in the countries worst hit by TB and HIV, he warned that an investment of over $600 million a year would be needed at country level for staff recruitment, training and improvement in diagnosis and infection control in order to contain the problem of multi-drug resistant TB.

“We run the risk of the replacement of a global epidemic of drug-susceptible TB with a catastrophe of drug-resistant TB that will have to be combated at vastly greater cost,” he concluded, noting that three countries - China, India and Russia - account for two-thirds of the world's cases of multidrug-resistant TB.