A low-cost antibiotic used to treat and prevent infections, including in people living with HIV, may decrease the burden of malaria in vulnerable communities, according to a new study co-authored by researchers at the University of Washington School of Public Health. The study was a collaboration with the Walter Reed Army Institute of Research, Kenya Medical Research Institute and Maseno University.
The drug, called cotrimoxazole, has been used since the early days of the HIV response to prevent infections such as pneumonia in HIV-infected individuals. It has also been shown to prevent malaria infection in children and adults undergoing antiretroviral therapy (ART).
The study, published Jan. 1 in The Journal of Infectious Diseases, found that, when HIV-infected adults receiving ART stopped contrimoxazole prophylaxis, there was a steady increase in malaria parasitemia prevalence and burden. Within a year of discontinuation, parasitemia prevalence reached 22 percent. Parasitemia is used as a measurement of parasite load, or the quantity of parasites in a person’s blood.
"Led by Drs. Ronald Ottichilo and John Waitumbi in Kenya, this study demonstrates that cotrimoxazole prophylaxis among HIV-infected individuals in high HIV prevalence settings has durable effects on malaria parasitemia, which could result in declines in malaria transmission,” Grace John-Stewart, professor of epidemiology and global health at the School of Public Health.
Researchers enrolled 500 HIV-infected adults receiving ART in a randomized trial conducted at the Homa Bay District Hospital, located in the Lake Victoria basin in western Kenya. Participants were randomized to either the CTX arm, a group that continued contrimoxazole prophylaxis, or the STOP-CTX arm, a group that discontinued contrimoxazole prophylaxis.
Participants were examined for malaria parasites every three months for a year and when they reported being sick. At enrollment, 95 percent of participants had no malaria parasitemia. A year after enrollment, malaria parasitemia was found in more than 20 percent of participants, all of which were in the STOP-CTX arm.
Researchers found that parasite prevalence in the STOP-CTX arm increased over time. Parasite prevalence was at 4 percent at the third month, 8 percent at the sixth month, 14 percent at the ninth month and 22 percent at the 12th month.