Low prevalence of placental malaria infection among pregnant women in Zanzibar: policy implications for IPTp

A Poster Presentation at the 61st Annual Meeting of the American Society of Tropical Medicine and Hygiene, 11-15 November 2012, Atlanta.

Marya Plotkin1, Khadija Said2, Natalie Hendler1, Asma R. Khamis1, Mwinyi I. Msellem3, Maryjane Lacoste1, Elaine Roman4, Veronica Ades5, Julie Gutman6, Raz Stevenson7, Peter McElroy8 – 1Jhpiego, Dar es Salaam, Tanzania, United Republic of, 2Ministry of Health Zanzibar, Zanzibar, Tanzania, United Republic of, 3Zanzibar Malaria Control Programme, Zanzibar, Tanzania, United Republic of, 4Jhpiego, Baltimore, MD, United States, 5University of California San Francisco, San Francisco, CA, United States, 6Centers for Disease Control and Prevention and President’s Malaria Initiative, Atlanta, GA, United States, 7United States Agency for International Development, Dar es Salaam, Tanzania, United Republic of, 8Centers for Disease Control and Prevention and President’s Malaria Initiative, Dar es Salaam, Tanzania, United Republic of

Efforts by the Zanzibar Ministry of Health to scale-up malaria prevention and treatment strategies, including intermittent preventive treatment for pregnant women (IPTp), have brought Zanzibar to the pre-elimination phase of malaria control. P. falciparum prevalence in the general population has been below 1% since 2008 and the diagnostic positivity rate among febrile patients was 1.2% in 2011.

dsc00497_tz-sm.jpgZanzibar implemented IPTp using sulfadoxine-pyrimethamine (SP) in 2004 when malaria prevalence exceeded 20%. While coverage among pregnant women is low (47% received two doses SP), the value of this intervention in low transmission settings remains uncertain. Few countries in Africa have confronted policy questions regarding timing of IPTp scale-down.

We designed a prospective observational study to estimate prevalence of placental malaria among pregnant women with no evidence of receiving any dose of SP for IPTp during pregnancy. From September 2011 to April 2012 we enrolled a convenience sample of pregnant women on day of delivery at six hospitals in Zanzibar (three in both Pemba and Unguja).

Dried blood spots (DBS) on filter paper were prepared from placental blood specimens. DBS were analyzed via polymerase chain reaction indicating active Plasmodium infection (all species). To date, over 1,200 deliveries were enrolled at the six recruitment sites (approximately 12% of total, range: 8-26%). Two (0.19%; 95% CI, 0.05-0.69%) of 1,046 DBS specimens analyzed to date showed evidence of P. falciparum infection. Both were from HIV uninfected, multigravid women in Unguja.

Birth weights for both deliveries were normal (>2500 g). Data collection will continue through the peak transmission season of May-July 2012. The very low prevalence of placental infection among women who received no IPTp raises policy questions regarding continuation of IPTp in Zanzibar. Alternative efforts to control malaria in pregnancy in Zanzibar, such as active case detection via regular screening and treatment during antenatal visits, should be evaluated.

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