Although MDR-TB and XDR-TB are particularly frightening, many healthcare staff in resource-limited settings are at routine risk of TB exposure. This is especially a problem for staff who are HIV-positive according to Dr Shona Dalal of the US Centers for Disease Control (CDC) who described a study investigating TB transmission at a large referral hospital in Nairobi, Kenya.
In 2004, the annual TB case rate in Kenya was 320/100,000, but in Nairobi it is much higher, 830/100,000, where over 60% of the population lives in slums. Coinfection is common — the HIV prevalence in adult TB patients is 60%.
In March 2005, there were exaggerated reports in the Kenyan press that the risk of contracting TB in the wards of a large referral hospital in Nairobi was eight times higher than in the general public. Concerned about the welfare of the hospital’s staff and its ability to retain 4,800 staff members — an especially precious resource in sub-Saharan Africa — the hospital launched an investigation into the problem in collaboration with the National Leprosy and Tuberculosis Programme and the CDC.
The hospital is a large 1,800-bed referral hospital in Nairobi — but overcrowding is common and patients often have to share beds while some sleep in mattresses on the floor. In 2004, a total of over 4,500 cases of TB were diagnosed at the hospital.
In addition to determining the burden of TB among the staff, the investigation ((a chart-review on staff TB cases and a case-controlled study) explored the risk factors for TB disease among the staff.
There were 215 TB cases among staff between 2001-2005, between 34-58 each year which is equivalent to a TB case rate of 645 to a high of 1,115 cases per 100,000 with no apparent trend from year to year. These TB rates were at least twice the national rate — though quite similar to the rate in Nairobi.
HIV might have been contributing to the high case rate of the staff, but the majority (66%) of staff TB cases did not have an HIV test result recorded in their medical charts (and only 71 of the staff had medical charts available). Of those who did have HIV results in their charts, 86% were HIV-positive.
Several risk factors, identified by multivariate logistic regression analysis, were associated with TB disease in the case-controlled study:
- Working in a high-risk location was associated with an adjusted odds ratio (AOR) of 2.1 (95% CI 1.1-4.2)
A high risk location was defined as any area in the hospital where TB patients received care including casualty/emergency room — where confirmed and suspected TB cases and other patients all shared the same crowded waiting areas which had limited ventilation — the general medical wards, and the TB clinic.
“The inpatient medical wards had confirmed TB patients segregated into two rooms, said Dr Dalal. “There were large windows in these rooms, but they were often closed, particularly at night. Sputum specimens were also sometimes collected at the bedside of inpatients.”
- The number of hours spent in the same room as patients per day, AOR 1.3 (95% CI 1.2-1.5)
- The staff member’s housing situation was also associated with TB, those living in the slums had an AOR of 4.7 (1.8-12.5), while those living in the hospital-provided low-income housing had an AOR of 2.6 (1.2-5.6).
- Being HIV-infected was the highest risk factor for TB, with an AOR of 29.1 (95% CI 5.1-167)
“HIV is the strongest known risk factor for progression to TB disease once infected,” said Dr Dalal. “For their own protection and to receive appropriate care, it is crucial for staff working in hospitals in a country with a generalized HIV epidemic and high rates of TB to know their HIV status.”
The Kenyan and South African data illustrate “the risk that health care workers of all sorts are facing and we’re having increasing difficulties retaining the health work force,” said DrAlistair Reed, HIV/TB advisor to UNAIDS. He noted that he had heard many healthcare workers express concerns about working around XDR-TB, especially.
Dr Friedland agreed this is potentially a very serious problem.
“One of the great vulnerabilities in this information is the effect that it might have on the healthcare staff, which is already quite stressed and in most circumstances there is insufficient staff to start with,” said Dr Friedland. “One of the great concerns is actually loss of staff. I think the institution of appropriate infection control procedures and HIV testing and education of the staff is very important.”
In another symposium, Dr de Cock also stressed that rapid action on infection control is crucial.
“Providing a safe working environment is going to have to be a priority,” he said, “because we cannot tolerate the impression to emerge that caring for AIDS patients or caring for TB patients is dangerous and is something that people won’t want to do. That is something that we just cannot allow to emerge.”