Drug Resistant Tuberculosis on the Rise
Girl being skin tested for TB.
GABORONE – Drug resistant tuberculosis is on the rise worldwide and countries like Botswana with high rates of HIV/TB co-infection should be especially vigilant in confronting the problem, a new report shows.
Drug-resistant TB accounts for nearly one in every 20 new cases of TB diagnosed worldwide, and extensively drug-resistant TB (or XDR TB) has been recorded in 45 countries, according to a report from the World Health Organization released earlier this year. Because so few African countries conduct drug resistance surveys, the extent of the problem is not well known on the continent. But it is likely there is drug resistance going unnoticed and undetected in these countries, says WHO TB expert Abigail Wright.
Health authorities in Botswana reported in January the first two known cases of XDR TB in Botswana and more than 100 cases of multi-drug resistant TB (MDR TB). Botswana is one of the few African countries conducting national drug-resistance surveys, and the results of the latest one are expected later in 2008. The results will be very important to understand the trends in drug resistance in this country and in other countries where HIV is prevalent.
In parts of the former Soviet Union, links between HIV and multi-drug resistance have already been made. Among people with HIV/TB coinfection in Latvia and Ukraine, for instance, the report found multi-drug resistant TB (MDR TB) was almost twice as common compared with people who had TB and were HIV negative. This trend is worrying for sub-Saharan Africa, where HIV and AIDS are "dramatically fueling the spread of TB," the WHO report says.
BOTUSA NEWS recently conducted a Q&A session with BOTUSA’s own TB/HIV section chief, Dr. Robert Makombe. In the interview, Dr. Makombe discusses definitions, prevention measures and treatment of drug resistant tuberculosis.
BN: What are the symptoms of TB?
Makombe: The general symptoms of TB include feelings of sickness or weakness, weight loss, fever, and night sweats. The symptoms of TB of the lungs may also include coughing, chest pain, and coughing up blood. Symptoms of TB in other parts of the body depend on the area affected. If you have these symptoms, you should contact your doctor or local clinic.
BN: Can you please explain the difference between multidrug-resistant tuberculosis (MDR TB) and extensively drug resistant tuberculosis (XDR TB)?
Dr. Robert Makombe
Makombe: Multidrug-resistant TB (MDR TB) is TB that is resistant to at least two of the best known anti-TB drugs, isoniazid and rifampicin. These drugs are considered first-line drugs and are used to treat all persons with TB disease.
Extensively drug resistant TB (XDR TB) is a relatively rare type of MDR TB. XDR TB is defined as TB which is resistant to isoniazid and rifampin, plus resistant to any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin). Because XDR TB is resistant to first-line and second-line drugs, patients are left with treatment options that are much less effective, more toxic and costly.
XDR TB is of special concern for persons with HIV infection or other conditions that can weaken the immune system. HIV positive people are more likely to develop active TB once they are infected with TB, and also have a higher risk of death once they develop active TB.
BN: How is drug resistant TB spread?
Makombe: Drug-susceptible TB and MDR TB are spread the same way. TB germs are put into the air when a person with TB of the lungs or throat coughs, sneezes, speaks, or sings. These germs can float in the air for several hours, depending on the environment. Persons who breathe in the air containing these TB germs can become infected. TB is not spread by shaking someone’s hand, sharing food or drink, touching bed linens or toilet seats, sharing toothbrushes or kissing.
BN: How does drug resistance happen?
Makombe: Resistance to TB drugs can occur when these drugs are misused or mismanaged. Examples include when patients do not complete their full course of treatment; when health-care providers prescribe the wrong treatment, the wrong dose, or length of time for taking the drugs; when the supply of drugs is not always available; or when the drugs are of poor quality.
BN: Who is at risk for getting MDR TB and XDR TB?
Makombe: Drug resistance is more common in people who:
do not take their TB medicine regularly;
do not take all of their TB medicine as told by their doctor or nurse;
develop active TB again, after having taken TB medicine in the past;
come from areas of the world where drug-resistant TB is common; and
have spent time with someone known to have drug-resistant TB disease.
BN: How are MDR TB and XDR TB prevented?
Makombe: The most important thing a person can do to prevent the spread of drug-resistant tuberculosis is to take all of their medications exactly as prescribed by their health care provider. No doses should be missed and treatment should not be stopped early. Patients should tell their health care provider if they are having trouble taking the medications. If patients plan to travel, they should talk to their health care providers and make sure they have enough medicine to last while away.
Health care providers can help prevent MDR TB and XDR TB by quickly diagnosing cases, following recommended treatment guidelines, monitoring patients’ response to treatment, and making sure therapy is completed.
Another way to prevent getting drug-resistant TB is to avoid exposure to known MDR TB and XDR TB patients in closed or crowded places such as hospitals, prisons, or homeless shelters. If you work in hospitals or healthcare settings where TB patients are likely to be seen, you should consult infection control or occupational health experts. Ask about administrative and environmental procedures for preventing exposure to TB.
Once those procedures are implemented, additional measures could include using personal respiratory protective devices.
BN: How long does it take to find out if you have MDR TB or XDR TB?
Makombe: If TB bacteria are found in the sputum (phlegm), the diagnosis of TB can be made in a day or two, but this finding will not be able to distinguish between drugsusceptible (regular) TB and drug-resistant TB. To determine drug susceptibility, the bacteria need to be grown and tested in a laboratory. Final diagnosis for TB, and especially for MDR TB and XDR TB, may take from 6 to 16 weeks.
BN: What is the link between XDR TB and HIV/AIDS?
Makombe: In places where XDR TB is most common, people living with HIV are at greater risk for developing the disease and dying because of their weakened immunity. If there are a lot of HIV-infected people in these places, then there will be a strong link between XDR TB and HIV. Fortunately, XDR TB is not widespread. For this reason, the majority of people with HIV who develop TB will have drug-susceptible or ordinary TB, and can be treated with standard firstline anti-TB drugs. For those with HIV infection, treatment with antiretroviral drugs will likely reduce the risk of developing XDR TB, just as it does with ordinary TB.
BN: Do children face any increased risk of TB or drug resistant TB? What special challenges must health workers consider when dealing with children and TB?
Makombe: Children living in close contact with someone with infectious TB are at increased risk of being infected with drugsensitive or drug-resistant TB. The risk of infection is greatest if the contact is close and prolonged, such as that between an infant or toddler and a mother or other caregivers in the household. The risk of developing the disease after infection is much greater for infants and young children under five years than it is for children aged five years or older. The risk is also greater in children infected with HIV.
The challenge of dealing with TB in children is that the disease is difficult to diagnose in children as it can present in many different and often subtle forms, particularly in the presence of HIV co-infection. All children with a cough who have been in close contact with someone with infectious TB must be screened for TB. When any child younger than 15 years is diagnosed with TB, efforts should be made to detect the source case (usually an adult with infectious TB), and any other undiagnosed cases in the household. If a child presents with infectious TB, child contacts must be sought and screened. Diagnosis may require special investigations and children with drug-resistant TB will need specialist pediatric care.
BN: What are international donors like PEPFAR doing to help the Government of Botswana to control drug resistant TB?
Makombe: U.S. support to TB/HIV-related activities in Botswana grew from $880,826 in 2006 to more than $4 million in 2007. PEPFAR has supported the revision of Botswana’s national guidelines containing internationally recommended TB management principles, including the correct diagnosis, treatment and follow-up of patients.
In collaboration with other technical and funding partners, PEPFAR has supported the development of national training curricula on TB/HIV for medical officers and nurses, and is funding the roll-out of trainings to increase the knowledge and skills of health care workers in Botswana in the proper management of all types of TB.
Insufficient laboratory capacity is a major obstacle to reliable and timely detection of drug-resistant TB. PEPFAR is supporting the Ministry of Health to improve the capacity of the National TB Reference Laboratory to perform high quality culture and drug susceptibility testing. BOTUSA has also facilitated the collaboration between the NTRL and a supranational reference laboratory based in South Africa as part of the process of improving quality-assured laboratory services.
Finally, BOTUSA is collaborating with MOH to develop a comprehensive programmatic approach to properly managing MDR TB, and PEPFAR is supporting the renovation of a TB isolation ward to the latest recommended standards.