Increased use of HIV treatment known as antiretrovirals (ARVs) in low- and middle-income countries has resulted in resistance to some forms of treatment, but not to the extent seen when HIV medication was first introduced in high-income countries in the 1990s, according to a new report from the World Health Organization (WHO).
Some 8 million people are now taking ARVs in low- and middle-income countries up from 400,000 in 2003. By 2010, the amount of HIV that was resistant to ARVs among people initiating treatment in the areas surveyed for the report, stood at 6.8 percent. Over a similar period of time after introducing ARVs in high income countries, slightly higher rates of drug resistance between 8 percent to 14 percent, depending on the region were being reported.
A number of factors have helped keep down levels of drug resistance in low- and middle-income countries. These include good program management and the use of simpler, more effective combinations of antiretrovirals than those originally introduced in high-income countries in the 1990s.
Simpler regimens using fixed-dose combinations have made it much easier for people to adhere to antiretroviral treatment, limiting the spread of drug resistance in recent years. This is good news for public health, says Dr. Gottfried Hirnschall, director of WHOs HIV department. Our task now is to ensure that drug resistance remains limited and manageable.
Some degree of HIV drug resistance is generally expected to occur due to natural mutations in the virus; but most cases of drug resistance are caused by preventable factors such as treatment interruptions and patients taking medicines incorrectly.
We need to make sure that people get the right medicines and that they stick to their treatment. This includes making sure that the drugs are easy to take, the supply is reliable, and that patients are followed closely to identify cases of treatment failure at an early stage, says Dr. Joseph Perrïens, of WHOs HIV Department.
Surveys in 12 low- and middle-income countries show that many health facilities currently lose contact with significant proportions (up to 38 percent) of people who start taking antiretrovirals. Loss of contact poses a serious threat to the control of drug resistance as most of these people interrupt or completely stop treatment. This not only means that they are themselves more likely to become sick, it also increases the likelihood that drug resistance will emerge and the resistant virus could be transmitted to others.
The surveys also highlight the need for stronger tracing and routine surveillance of HIV drug resistance in low- and middle-income countries to alert programme planners to patterns of drug resistance.
WHO recommends that every clinic providing antiretroviral treatment should use a set of early warning indicators to identify and address factors that could cause drug resistance. Indicators include:
- adherence to treatment
- the type of medicines used
- continuity of drug supply
- the extent to which patients continue to access services
At sites where patients can routinely have the amount of virus in their blood tested, WHO also recommends monitoring how well the medicine is suppressing a patients amount of HIV at 12 months to identify treatment failure at an early stage. A rise in the amount of virus a patient has in their blood is an indicator that the current treatment is failing.
To support these recommendations, the WHO has created a global network of surveillance laboratories and collaborating institutions to monitor HIV drug resistance and to exchange information with HIV programs and technical partners. The WHO is also working to improve the laboratory capacity in countries to improve their ability to study the genetic makeup of the viruses and whether they are resistant to medicines. Understanding genetic patterns of drug resistance helps healthcare workers provide more effective, longer-lasting treatment options to patients.