番茄社区

NEW ORLEANS -- Papua New Guinea saw a major resurgence of malaria after a "previously unprecedented decline," a researcher said here.

Over the last 3 years, the historic declines in malaria prevalence to <1% in 2013-2014 have been offset with an increase to 7.1% in 2017 in Papua New Guinea, reported Manuel Hetzel, PhD, of Swiss Tropical and Public Health Institute in Basel, Switzerland at the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting.

For people infected with malaria parasites detectable by light microscopy, there was an 8.6-fold increase in malaria prevalence from 50,309 to 432,000 from 2014 to 2017, Hetzel reported. Previous malaria control initiatives involved indoor residual spraying and mass distribution of chloroquine. When these efforts ended, there was the first massive resurgence of malaria, he added.

To address this resurgence, the was initiated, and involved free distribution of long-lasting insecticide nets (LLIN) and artemisinin-based combination therapy (ACT), Hetzel noted.

The data from the malaria indicator surveys (MIS) used sampling from five to eight random villages from each province, 30 random houses for each village, and included all family members ages >6 months.

The participants were assessed through framed interviews with heads of household and the kids' caregivers. The participants were finger-pricked in order to gather a blood sample for malaria microscopy testing.

The researchers gathered the following sample surveys:

• 2008-2009: from 49 villages, 1,958 households, 6,646 blood samples
• 2010-2011: 77 villages, 1,996 households, 10,060 blood samples
• 2013-2014: 92 villages, 2,167 households, 8,408 blood samples
• 2016-2017: 102 villages, 2,739 households, 11,430 blood samples

The prevalence of malaria below 1,600 m altitude for any species was 11.1% in 2009, 5.1% in 2011, and 0.9% in 2014. In 2016-2017, the malaria prevalence for adults was 0.9% in highlands of 1,600-plus m in altitude.

There were a number of factors that contributed to this malaria resurgence, such as vector control coverage, treatment coverage, human behavior, and mosquito ecology.

The data showed that 2.7 million people did not have LLIN at home.

Hetzel noted factors that could have contributed to resurgence as a result of treatment coverage:

• 41% health facility attendance
• Limited availability of Artemether-lumefantrine (AL)
• Wide-spread drug shortages
• Limited availability and poor treatment adherence to radical cure of (14-day ACT-primaquine regimen)

With regard to mosquito ecology, there were differences in the mosquito's biting behavior, such as more biting early in the evening; differences in species makeup, and lack of insecticide resistance, Hetzel stated.

In the southern region of Papua New Guinea, the prevalence of malaria for those ages 10-14 years was just over 10% for males and about 2.5% for females. In the Momase region, the prevalence of malaria for ages 5-9 years was just under 25% in males and just over 15% for females.

"The current malaria resurgence is likely to worsen unless malaria control is re-intensified without delay, inclusive of sufficient funding for vector control, diagnosis, treatment, awareness campaigns, and operational research," Hetzel said.

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