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Primaquine best for malaria prevention, researchers say
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Primaquine should be the drug of choice for chemoprophylaxis for two malaria-causing pathogens in areas where they co-circulate, according to researchers.
Other drugs were less effective, particularly against late-onset malaria, they wrote in Clinical Infectious Diseases.
“Our study clearly demonstrates the superiority of primaquine over all other chemoprophylactic agents currently recommended for the prevention of malaria in people who travel to areas highly endemic for both Plasmodium falciparum and P. vivax,” researcher Eyal Meltzer, MD, of the Center for Geographic Medicine & Tropical Diseases at the Chaim Sheba Medical Center in Tel Hashomer, Israel, and colleagues wrote.
To test the efficacy of the available malaria drugs, the researchers conducted a retrospective observational study that included Israeli rafters who had visited Ethiopia’s Omo River, located in a malaria-endemic region, over an 11-year period. The researchers followed 252 travelers for at least 1 year after their return to Israel. None of the travelers visited malaria-endemic regions during the study’s follow-up, the researchers said.
For malaria prophylaxis, 54 travelers received mefloquine, 23 received doxycycline, 145 received primaquine and 30 received Malarone (atovaquone-proguanil, GlaxoSmithKline).
In all, 62 travelers (24.6%) developed malaria. P. vivax was the pathogen responsible in 57 cases (91.9%), and P. falciparum was the cause of the remaining illnesses. Fifty-four malaria cases (87.1%) were deemed late malaria, developing more than 1 month after exposure. All late malaria cases were caused by P. vivax.
Prophylaxis failure rates for early and late malaria combined were 56.7% for atovaquone-proguanil, 52.2% for doxycycline, 49% for mefloquine and 5.5% for primaquine. None of the study’s malaria cases were fatal, the researchers said.
Late-onset malaria occurred in 56.7%, 49%, 43.5% and 1.4% of travelers receiving atovaquone-proguanil, mefloquine, doxycycline and primaquine, respectively.
Meltzer and colleagues noted that their data highlight the significance of a longer follow-up period in detecting late-onset malaria. Late-onset disease can often occur when hypnozoites — malaria parasites lying dormant in the liver — are reactivated, they said.
“In prospective malaria chemoprophylaxis studies to date, follow-up has usually been limited to 1 month post-exposure and in the absence of a prolonged follow-up period, all late infections of P. vivax and P. ovale malaria will be missed,” the researchers wrote. “In fact, had the follow-up in our study been limited to 1 month post-exposure, the efficacy of all agents would have been deemed excellent, approaching 100%.” – by Joe Green
Disclosures: The authors report no relevant financial disclosures.
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