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Current WHO strategy not enough to eliminate yaws, researchers say
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A WHO-adopted strategy that aims to eliminate yaws in endemic areas through the mass administration of a single round of azithromycin significantly reduced the number of cases in Papua New Guinea 1 year after implementation. However, recent data published in The Lancet showed that yaws had re-emerged months later, underscoring the need to modify WHO’s current policy.
In addition to an increase in yaws incidence, Oriol Mitjà, MD, researcher at the Barcelona Institute for Global Health (ISGlobal), and colleagues detected azithromycin resistance in the Treponema pallidum subspecies pertenue (T p pertenue), the pathogen that causes yaws. This is the first time that resistance to azithromycin has been reported in patients with the infection, according to the researchers.
“This study reveals the urgent need to include drug resistance monitoring as part of the WHO yaws eradication strategy,” Antoni Plasència, MD, director general of ISGlobal, said in a press release.
Mitjà and colleagues examined the impact of a mass drug administration (MDA) with a single dose of azithromycin that was given to 83.4% of the population on a Papua New Guinea island. The researchers followed participants for 42 months after treatment and conducted active case detection surveys every 3 to 6 months.
The prevalence of active yaws cases significantly decreased 18 months after the MDA from 1.8% to 0.1% (P < .0001). After 24 months, however, yaws began to re-emerge, and the incidence significantly increased to 0.4% by 42 months (P < .0001). Approximately half of new infections occurred in participants who were absent of the time of the MDA.
Five participants with active yaws infection had clinical treatment failure that was due to azithromycin resistance. All five patients were cured after receiving treatment with benzathine benzylpenicillin, according to the researchers.
To achieve WHO’s goal of yaws eradication, Mitjà and colleagues recommended that future MDAs distribute at least two to three rounds of azithromycin treatment every 6 to 12 months to more than 90% of the population. The researchers plan on launching another trial in Papua New Guinea to identify the optimal number of treatment rounds needed to eliminate yaws.
To address the issue of resistance, the researchers recommend strengthening laboratory surveillance capacities in endemic countries. They also called for guidance on prescribing benzathine benzylpenicillin in patients who do not respond to treatment with azithromycin.
In a related editorial, David Smajs, PhD, and Petra Pospísilová, PhD, of the department of biology at Masaryk University, Czech Republic, further recommended shortening the duration between treatment and active case detection to 2 months to identify treatment failure sooner.
“This measure will likely decrease the efficiency with which macrolide-resistant T p pertenue can spread even if additional costs will be required,” they wrote. – by Stephanie Viguers
Disclosures: The authors report no relevant financial disclosures.
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