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KENYA: PMTCT could cause drug resistance in positive infants
A mother breastfeeds her child
KISUMU, 6 May 2011 (IRIN) - Drug regimens used in the prevention of mother-to-child transmission (PMTCT) of HIV are effective, but infants should be monitored for drug resistance, a new study has revealed.
The study in Kisumu, western Kenya, found that the triple combination of antiretroviral (ARV) drugs given to HIV-infected mothers to prevent transmission of the virus to their infants was effective and feasible, but there were cases of possible drug resistance in HIV-positive infants.
The Kisumu Breastfeeding Study
(KiBS) by the Kenya Medical Research Institute and the Centre for Disease Control covered 522 HIV-positive mothers, 310 of whom were prescribed a nevirapine-based regimen, and 212 were placed on a nelfinavir-based regimen.
“The… study documented transmission rates of seven percent (32 infants were positive) at 24 months, most of which were due to transmission in-utero or during delivery,” said Dr Timothy Thomas, one of the study’s leading researchers.
These HIV transmission rates are comparable to those recorded in similar trials conducted in other resource-limited settings, and were 77 percent lower than mother-to-child transmission rates observed in a previous Kisumu study, in which no ARVs were used (4.6 percent compared to. 19.9 percent at 4 months).
“While results of this study, and others, indicate that antiretroviral regimens given to HIV-infected women from late pregnancy through six months of breastfeeding is a safe, feasible way to reduce mother-to-child transmission of HIV, this study found that low amounts of some ARVs are transferred from mother to infant in breast milk, and this exposure to sub-optimal ARV levels may cause resistance to ARVs among HIV-infected infants,” said the study’s lead researcher, Dr Clement Zeh.
During the six-month breastfeeding period after birth, 24 infants were diagnosed as HIV positive. Of the 15 infants breastfed by mothers on the nevirapine-based regimen, seven developed resistance, while all the nine infants breastfed by mothers on the nelfinavir-based regimen developed resistance.
The researchers suggested that the drug resistance might be attributable to low levels of ARVs in breast milk, rather than mother-to-child transmission of a drug-resistant virus.
“KiBS found low HIV transmission rates and demonstrated the feasibility and safety of the use of a maternal triple-antiretroviral regimen, given from late pregnancy through the first six months of breastfeeding, among HIV-positive women,” Dr Zeh noted.
“These findings reinforce the WHO [World Health Organization] recommendation of exclusive breastfeeding for HIV-exposed infants in resource-limited settings where acceptable, feasible, affordable and sustainable, and where safe replacement feedings cannot be achieved,” he said.
“The antiretrovirals used are relatively safe and the substantial reduction in risk of transmission of HIV with use of antiretrovirals during breastfeeding outweighs the risk of exposure to the antiretrovirals.”
An estimated half a million children, many in poor countries, are infected with the virus. Without the intervention of mother-to child-transmission programmes, 25 percent to 50 percent run the risk of being infected during pregnancy, birth or breastfeeding.
In Kenya there were an estimated 110,000 HIV-positive pregnant women in 2008, but less than a third were given nevirapine.
The study’s authors called on providers to consider the mother’s regimen when choosing treatment for HIV-infected infants, despite the triple-drug regimen prophylaxis, and to monitor the response of infants to the therapy.
“There have been reported cases of antiretroviral resistance amongst infants in health facilities, but it has largely been linked by health workers to poor adherence,” said Dr Mohamed Ibrahim, head of Kenya’s National AIDS and STI [Sexually Transmitted Infection] Control Programme.
“I think the study is important, so that health workers are sensitized to the need to be more vigilant, because putting children on second-line treatment for HIV is very expensive.”
The government has promoted exclusive breastfeeding by HIV-positive mothers, but despite its importance in preventing HIV in infants, the Kenya Demographic and Health Survey 2008-09 estimated that just under 32 percent of infants were exclusively breastfed for six months after birth.