Over the past couple of weeks there have been much discussion and reporting on totally drug-resistant tuberculosis (TDR-TB) based on reports of new cases in India. Here are links to coverage of TDR-TB in India, excerpt from a response by Dr. Nardell who we interviewed last year, and link to the WHO Fact Sheet on TDR-TB.
Excerpt from e-mail from Dr. Edward Nardell on January 12, 2012 to the CORE Group–TB in response to the article on NPR.org:
“While the emergence and spread of highly drug resistant strains has been a long-standing concern, strains resistant to all drugs is not new, and has been a by-product of introducing treatment for MDR TB long before XDR TB. Having been engaged early on in the treatment of MDR TB in Peru, Haiti, and Russia, PIH has encountered highly drug resistant strains, now called XDR and TDR, long before there were any headlines about them. Others have seen the same. Such cases were simply called MDR treatment failures and became chronic cases. As MDR treatment has spread, their numbers have increased. No treatment = no resistance, but that is hardly a solution. Well supervised treatment results in less resistance, of course, but even well supervised treatment can induce some resistance and it can spread in families and congregate settings. Like XDR, TDR will generate headlines and may generate some beneficial resources, but there is nothing new in principle here. Certainly we have a problem with DST’s for second-line drugs. Two good labs may not agree on resistance patterns which make the reporting of MDR, XDR, and TDR always questionable, but again, in principle, the emergence of such strains, when confirmed, is not surprising or new.”
Edward A. Nardell, MD, Associate Professor, Harvard Medical School (Medicine; Global Health and Social Medicine), Harvard School of Public Health (Environmental Health; Immunology and Infectious Diseases)
Additional TB R&D News: