In December last year the public’s attention was drawn to the threat posed to society by resistant strains of tuberculosis (TB) when 49 patients infected with deadly and highly infectious strains of drug-resistant TB escaped from Jose Pearson Hospital near Port Elizabeth in the Eastern Cape. Their escape made national headlines and highlighted again the need for swift and effective medical care.
These new strains of TB are the multi-drug resistant strain (MDR-TB) and the extensively resistant strain (XDR-TB). They pose a threat because of their resistance to some of the drug lines available to treat TB.
Professor Prashini Moodley of the University of KwaZulu-Natal explained that MDR-TB is resistant to the first line of drugs used to treat TB and that XDR-TB is resistant to the second line of drugs. In terms of XDR-TB doctors are uncertain about the effectiveness of the third line of drugs available.
“What makes the new strains of TB so difficult to treat is that it often takes longer to diagnose drug-resistant TB,” Moodley said. This delay means that doctors are unsure how to proceed until a diagnosis has been made. In addition, the symptoms of the three different types of TB are similar, which means that someone could be infected with the drug-resistant strain and not realise it.
Moodley said that “all types of TB are transmissible, in the same way, regardless of whether that person has one of the types of TB or not”.
TB that is susceptible to or treatable with all drugs can become resistant to these drugs through a number of ways. Patients might not take their medication correctly or not complete the full course. They can also be given the incorrect dosage by doctors, or be badly supervised by medical personnel. Either way, the drug-resistant types of TB are becoming an increasingly serious problem.
According to an article by medical researchers Jerome Singh, Ross Upshur and Nesri Padayatchi, published in PLoS Medicine, an open-access, peer reviewed medical journal, there are at least 30 new cases of XDR-TB reported each month in KwaZulu-Natal alone. The situation in South Africa is a particularly difficult one because the true extent of the problem is not fully known. People might not be aware that they are infected with the drug-resistant strains and they also might not come forward to medical authorities, they said.
Resource availability in South Africa worsens the situation. Medical professionals might not have access to the necessary medical supplies to identify, treat and monitor the different types of TB that patients might present. According to Singh, Upshur and Padayatchi, only about half of South African patients are cured of active TB, instead of about 80% of those in countries that have access to better resources.
“In terms of XDR-TB medical professionals are not sure about the effectiveness of the third line drugs available to treat this type,” said Moodley.
The new drug-resistant strains also pose a danger to HIV-positive patients because they can further weaken the immune systems of the patients. “TB affected the young and old in the past,” said Moodley.
“However, TB infections are now being found mainly with the setting of HIV infection, and the age distribution of TB now mimics that of HIV infection.”
The public needs to know about drug-resistant TB and how to avoid becoming infected with TB altogether. Educational programmes, which provide information about preventing TB, are available to the public from the department of health. Professor Moodley said that, if a teacher suspected a child of being infected with TB, he or she should refer the child to the nearest health clinic.