Baseline characteristics for phase II of the Kinshasa Malaria Cohort Study: cohort profile

Abstract

Purpose: The Democratic Republic of Congo has one of the highest burdens of malaria in the world, accounting for 12.3% of malaria cases and 11.6% of malaria deaths. The country has been scaling up various malaria control interventions, but how the malaria burden and risk factors have evolved remains unclear. This study aimed to estimate the trend in the burden of malaria in different settings in Kinshasa Province and assess factors contributing to the infection.

Participants: From 2018 to 2022, a cohort study was conducted in three health areas in Kinshasa Province known to have varying malaria endemicities: Voix du Peuple (urban), Kimpoko (peri-urban), and Bu (rural) health areas in Kinshasa Province. Participants 6 months of age and older were recruited and followed biannually through household visits and encouraged to visit study health centres whenever they felt ill. The participants' sociodemographic data, illness history and access to malaria interventions were collected along with blood specimens. During the same study period, mosquitoes and larvae were collected to study entomological characteristics that may contribute to malaria transmission.

Findings: A total of 1635 participants were recruited from 239 households. The median number of participants per household was 6 (IQR, 5-9). Over half (54.7%) of the participants were female, 14.6% were under-5 children, and 33.3% were 5-14 years old. Household net ownership and reported use the previous night were 77.8% and 79.1%, respectively. Overall, malaria prevalence by rapid diagnostic test at baseline was 33.4%. Of the recruited participants, 1390 (85%) completed the 4 years of follow-up.

Future plans: Planned analyses include calculating malaria prevalence and incidence trends at follow-up as well as risk factors for infection. Continued analyses will link epidemiological and entomological data to understand malaria transmission evolution and the sustained high prevalence of malaria over time in various settings.

Keywords: EPIDEMIOLOGY; Malaria; Observational Study.

Figure 1. Location of the seven study sites within the two health zones.

Figure 2. Study overview. The figure depicts the three types of data collection over the study period 2018–2022: active, passive and entomological surveillance. Blue-shaded boxes represent the rainy season. Yellow-shaded boxes represent the dry season. Mosquito icons represent mosquito catches. Circled mosquitoes represent larvae collection. FU6, follow-up 6.

Figure 3. This figure represents the participant flow from the enrolment at baseline to the study’s last completed household visit. Participant retention was 85%.