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

Malaria Journal

Ummi Abdul Kibondo¹  Thabit Athuman¹  Salim Abdulla¹  Maxmillian Mpina²  Said Abdallah Jongo³  Guillermo A. García³  Carlos Cortez Falla³  Jeremías Nzamio Mba Eyono³  Jordan Michael Smith³  Ally Olotu⁴  Kassim Kamaka⁴  Ali Mtoro⁴  Elizabeth Nyakarungu⁴  Ali Hamad Said⁴  Raul Chuquiyauri⁵  Genaro Nsue Nguema Okomo⁶  Juan Carlos Momo Besaha⁶  Fortunata Lobede Mochomuemue⁶  Gertrudis Owono Bidjimi⁶  Vicente Urbano Nsue Ndong Nchama⁶  Marta Alene Owono⁶  Beltran Ekua Ntutumu Pasialo⁶  Mariano Obiang Obono⁶  Maria-Silvia Angue Lopez⁶  José Raso⁶  Martin Eka Ondo Mangue⁶  Dolores Mbang Ondo⁶  Escolastica Raquel Mansogo Maye⁶  Thomas L. Richie⁷  L. W. Preston Church⁷  Peter F. Billingsley⁷  Stephen L. Hoffman⁷  B. Kim Lee Sim⁷  Laurence Lemiale⁷  Claudia Daubenberger⁸  Marcel Tanner⁸  Tobias Schindler⁸ 

[1] Ifakara Health Institute, Dar es Salaam, Tanzania;Ifakara Health Institute, Dar es Salaam, Tanzania;Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland;University of Basel, Basel, Switzerland;Medical Care Development International (MCDI), Silver Spring, USA;Medical Care Development International (MCDI), Silver Spring, USA;Ifakara Health Institute, Dar es Salaam, Tanzania;Medical Care Development International (MCDI), Silver Spring, USA;Sanaria Inc., Rockville, USA;Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea;Medical Care Development International (MCDI), Silver Spring, USA;Sanaria Inc., Rockville, USA;Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland;University of Basel, Basel, Switzerland;

关键词: Malaria;    Plasmodium falciparum;    Incidence;    PfSPZ Vaccine;    Malabo;    Bioko Island;    Equatorial Guinea;   

DOI  :  10.1186/s12936-021-03850-8

来源: Springer

【 摘 要 】

BackgroundExtensive 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.MethodsA 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.ResultsThere 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.ConclusionDespite intensive malaria control efforts on Bioko Island, local transmission remains and is spread evenly throughout age groups. These incidence rates indicate moderate malaria transmission which may be sufficient to support future larger trials of PfSPZ Vaccine. The long-term goal is to conduct mass vaccination programmes to halt transmission and eliminate P. falciparum malaria.

【 授权许可】

CC BY