DURBAN, South Africa, Oct. 23 (UPI) -- Researchers in South Africa say a 2001 World Health Organization program may have inadvertently help create a new strain of drug-resistant tuberculosis.

The study, published in Clinical Infectious Diseases, found the strain had been already resistant to one or more drugs mandated by the 2001 strategy, allowing the strain to survive and develop resistance to additional drugs.

"The spread of a highly transmissible strain of drug-resistant tuberculosis has been facilitated by applying standard treatment regimens for susceptible and multi-drug resistant tuberculosis in the absence of drug resistance surveillance," one of the study authors, Dr. A. Willem Sturm, of the University of KwaZulu-Natal’s Nelson R. Mandela School of Medicine in South Africa said in a statement.

"Public health programs for the treatment and control of infectious diseases need to be supported by drug resistance surveillance programs."

Drug susceptibility tests would have warned doctors that the standard regimen was unlikely to help the patient but was likely to lead to additional drug-resistance. These tests were not performed or were not available in South Africa in 2001, the researchers said.