Incidence of Plasmodium falciparum malaria infection in 6-month to 45-year-olds on selected areas of Bioko Island, Equatorial Guinea

• Published in: Malaria Journal
• Main Authors: Vicente Urbano Nsue Ndong Nchama, Ali Hamad Said, Ali Mtoro, Gertrudis Owono Bidjimi, Marta Alene Owono, Escolastica Raquel Mansogo Maye, Martin Eka Ondo Mangue, Genaro Nsue Nguema Okomo, Beltran Ekua Ntutumu Pasialo, Dolores Mbang Ondo, Maria-Silvia Angue Lopez, Fortunata Lobede Mochomuemue, Mariano Obiang Obono, Juan Carlos Momo Besaha, Raul Chuquiyauri, Said Abdallah Jongo, Kassim Kamaka, Ummi Abdul Kibondo, Thabit Athuman, Carlos Cortez Falla, Jeremías Nzamio Mba Eyono, Jordan Michael Smith, Guillermo A. García, José Raso, Elizabeth Nyakarungu, Maxmillian Mpina, Tobias Schindler, Claudia Daubenberger, Laurence Lemiale, Peter F. Billingsley, B. Kim Lee Sim, Thomas L. Richie, L. W. Preston Church, Ally Olotu, Marcel Tanner, Stephen L. Hoffman, Salim Abdulla
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2021
• Subjects: Malaria; Plasmodium falciparum; Incidence; PfSPZ Vaccine; Malabo; Bioko Island; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-021-03850-8; https://doaj.org/article/3e7774f81b3642fb8979372514e81536

Abstract Background Extensive malaria control measures have been implemented on Bioko Island, Equatorial Guinea over the past 16 years, reducing parasite prevalence and malaria-related morbidity and mortality, but without achieving elimination. Malaria vaccines offer hope for reducing the burden to zero. Three phase 1/2 studies have been conducted successfully on Bioko Island to evaluate the safety and efficacy of whole Plasmodium falciparum (Pf) sporozoite (SPZ) malaria vaccines. A large, pivotal trial of the safety and efficacy of the radiation-attenuated Sanaria® PfSPZ Vaccine against P. falciparum is planned for 2022. This study assessed the incidence of malaria at the phase 3 study site and characterized the influence of socio-demographic factors on the burden of malaria to guide trial design. Methods A cohort of 240 randomly selected individuals aged 6 months to 45 years from selected areas of North Bioko Province, Bioko Island, was followed for 24 weeks after clearance of parasitaemia. Assessment of clinical presentation consistent with malaria and thick blood smears were performed every 2 weeks. Incidence of first and multiple malaria infections per person-time of follow-up was estimated, compared between age groups, and examined for associated socio-demographic risk factors. Results There were 58 malaria infection episodes observed during the follow up period, including 47 first and 11 repeat infections. The incidence of malaria was 0.25 [95% CI (0.19, 0.32)] and of first malaria was 0.23 [95% CI (0.17, 0.30)] per person per 24 weeks (0.22 in 6–59-month-olds, 0.26 in 5–17-year-olds, 0.20 in 18–45-year-olds). Incidence of first malaria with symptoms was 0.13 [95% CI (0.09, 0.19)] per person per 24 weeks (0.16 in 6–59-month-olds, 0.10 in 5–17-year-olds, 0.11 in 18–45-year-olds). Multivariate assessment showed that study area, gender, malaria positivity at screening, and household socioeconomic status independently predicted the observed incidence of malaria. Conclusion Despite intensive malaria control ...