Hepatitis B Virus Prevalence and Transmission in the Households of Pregnant Women in Kinshasa, Democratic Republic of Congo

Background

The World Health Organization Africa region has high regional hepatitis B virus (HBV) prevalence, and evidence suggests more frequent horizontal HBV transmission than other regions. Context-specific epidemiological studies are needed to inform additional HBV prevention measures.

Methods

In the cross-sectional Horizontal and Vertical Transmission of Hepatitis B (HOVER-HBV) study, we introduced HBV surface antigen (HBsAg) screening alongside existing HIV screening as part of routine antenatal care in high-volume maternity clinics in Kinshasa, Democratic Republic of Congo. We recruited households of pregnant women ("index mothers") who were HBsAg-positive and HBsAg-negative, defining households as index-positive and index-negative, respectively. Household members underwent HBsAg testing and an epidemiological survey. We evaluated HBsAg prevalence and potential transmission correlates.

Results

We enrolled 1006 participants from 200 households (100 index-positive, 100 index-negative) across Kinshasa. HBsAg-positivity prevalence was more than twice as high in index-positive households (5.0% [95% confidence interval {CI}, 2.8%-7.1%]) as in index-negative households (1.9% [95% CI, .6%-3.2%]). HBsAg-positivity prevalence was 3.3 (95% CI, .9-11.8) times as high among direct offspring in index-positive versus index-negative households. Factors associated with HBsAg positivity included older age, marriage, and having multiple recent partners or any new sexual partners among index mothers; and older age, lower household wealth, sharing nail clippers, and using street salons among offspring in index-positive households.

Conclusions

Vertical and horizontal HBV transmission within households is ongoing in Kinshasa. Factors associated with infection reveal opportunities for HBV prevention efforts, including perinatal prevention, protection during sexual contact, and sanitation of shared personal items.

Using intervention mapping to develop an implementation strategy to improve timely uptake of streamlined birth-dose vaccines in the Democratic Republic of the Congo

Despite the policy recommendation and effectiveness of administering the hepatitis B birth-dose vaccine (HepB-BD) to newborns to prevent mother-to-child hepatitis B transmission, timely uptake remains an issue. Countries adopting the HepB-BD to their national immunization schedule report programmatic challenges to administering the vaccine within the recommended 24-hour window after delivery. Further, while the World Health Organization recommends streamlining three birth-dose vaccines (HepB-BD, BCG, and OPV0), scarce Sub-Saharan(SSA)-based literature reports on a streamlined and timely approach to birth-dose vaccines. As more SSA countries adopt the new birth-dose vaccine to their immunization schedules, a systematically developed implementation strategy-Vaccination of Newborns-Innovative Strategies to Hasten Birth-Dose vaccines' delivery (VANISH-BD)-will facilitate the adoption and implementation of timely birth-dose vaccine uptake. In this paper, we describe the development of the implementation strategy using intervention mapping, an evidence-based and theory-driven approach. We report on the development of our intervention, beginning with the needs assessment based in Kinshasa Province, Democratic Republic of the Congo (DRC), informing step 1 of intervention mapping. The intervention is contextually relevant, locally produced, sustainable, and designed to improve timely birth-dose vaccine uptake in the DRC. We intend to inform future implementers about improving timely and streamlined birth-dose vaccine uptake and for VANISH-BD to be adapted for similar contexts.

Childhood immunization uptake determinants in Kinshasa, Democratic Republic of the Congo: ordered regressions to assess timely infant vaccines administered at birth and 6-weeks

BACKGROUND

Despite global efforts to reduce preventable childhood illness by distributing infant vaccines, immunization coverage in sub-Saharan African settings remains low. Further, timely administration of vaccines at birth-tuberculosis (Bacille Calmette-Guérin [BCG]) and polio (OPV0)-remains inconsistent. As countries such as Democratic Republic of the Congo (DRC) prepare to add yet another birth-dose vaccine to their immunization schedule, this study aims to improve current and future birth-dose immunization coverage by understanding the determinants of infants receiving vaccinations within the national timeframe.

METHODS

The study used two ordered regression models to assess barriers to timely BCG and first round of the hepatitis B (HepB3) immunization series across multiple time points using the Andersen Behavioral Model to conceptualize determinants at various levels. The assessment leveraged survey data collected during a continuous quality improvement study (NCT03048669) conducted in 105 maternity centers throughout Kinshasa Province, DRC. The final sample included 2398 (BCG analysis) and 2268 (HepB3 analysis) women-infant dyads living with HIV.

RESULTS

Between 2016 and 2020, 1981 infants (82.6%) received the BCG vaccine, and 1551 (68.4%) received the first dose of HepB3 vaccine. Of those who received the BCG vaccine, 26.3%, 43.5%, and 12.8% received BCG within 24 h, between one and seven days, and between one and 14 weeks, respectively. Of infants who received the HepB3 vaccine, 22.4% received it within six weeks, and 46% between six and 14 weeks of life. Many factors were positively associated with BCG uptake, including higher maternal education, household wealth, higher facility general readiness score, and religious-affiliated facility ownership. The factors influencing HepB3 uptake included older maternal age, higher education level, household wealth, transport by taxi to a facility, higher facility general and immunization readiness scores, and religious-affiliated facility ownership.

CONCLUSIONS

This study demonstrated that the study participants' uptake of vaccines was consistent with the country average, but not in a timely manner. Various factors were associated with timely uptake of BCG and HepB3 vaccines. These findings suggest that investment to strengthen the vaccine delivery system might improve timely vaccine uptake and equity in vaccine coverage.

Plasmodium falciparum with pfhrp2/3 Deletion Not Detected in a 2018-2021 Malaria Longitudinal Cohort Study in Kinshasa Province, Democratic Republic of the Congo

Histidine-rich protein 2- (HRP2-) based rapid diagnostic tests (RDTs) are widely used to detect Plasmodium falciparum in sub-Saharan Africa. Reports of parasites with pfhrp2 and/or pfhrp3 (pfhrp2/3) gene deletions in Africa raise concerns about the long-term viability of HRP2-based RDTs. We evaluated changes in pfhrp2/3 deletion prevalence over time using a 2018-2021 longitudinal study of 1,635 enrolled individuals in Kinshasa Province, Democratic Republic of the Congo (DRC). Samples collected during biannual household visits with ≥ 100 parasites/µL by quantitative real-time polymerase chain reaction were genotyped using a multiplex real-time PCR assay. Among 2,726 P. falciparum PCR-positive samples collected from 993 participants during the study period, 1,267 (46.5%) were genotyped. No pfhrp2/3 deletions or mixed pfhrp2/3-intact and -deleted infections were identified in our study. Pfhrp2/3-deleted parasites were not detected in Kinshasa Province; ongoing use of HRP2-based RDTs is appropriate.

Impact of malaria diagnostic choice on monitoring of Plasmodium falciparum prevalence estimates in the Democratic Republic of the Congo and relevance to control programs in high-burden countries

Malaria programs rely upon a variety of diagnostic assays, including rapid diagnostic tests (RDTs), microscopy, polymerase chain reaction (PCR), and bead-based immunoassays (BBA), to monitor malaria prevalence and support control and elimination efforts. Data comparing these assays are limited, especially from high-burden countries like the Democratic Republic of the Congo (DRC). Using cross-sectional and routine data, we compared diagnostic performance and Plasmodium falciparum prevalence estimates across health areas of varying transmission intensity to illustrate the relevance of assay performance to malaria control programs. Data and samples were collected between March-June 2018 during a cross-sectional household survey across three health areas with low, moderate, and high transmission intensities within Kinshasa Province, DRC. Samples from 1,431 participants were evaluated using RDT, microscopy, PCR, and BBA. P. falciparum parasite prevalence varied between diagnostic methods across all health areas, with the highest prevalence estimates observed in Bu (57.4-72.4% across assays), followed by Kimpoko (32.6-53.2%), and Voix du Peuple (3.1-8.4%). Using latent class analysis to compare these diagnostic methods against an "alloyed gold standard," the most sensitive diagnostic method was BBA in Bu (high prevalence) and Voix du Peuple (low prevalence), while PCR diagnosis was most sensitive in Kimpoko (moderate prevalence). RDTs were consistently the most specific diagnostic method in all health areas. Among 9.0 million people residing in Kinshasa Province in 2018, the estimated P. falciparum prevalence by microscopy, PCR, and BBA were nearly double that of RDT. Comparison of malaria RDT, microscopy, PCR, and BBA results confirmed differences in sensitivity and specificity that varied by endemicity, with PCR and BBA performing best for detecting any P. falciparum infection. Prevalence estimates varied widely depending on assay type for parasite detection. Inherent differences in assay performance should be carefully considered when using community survey and surveillance data to guide policy decisions.

Association between domesticated animal ownership and Plasmodium falciparum parasite prevalence in the Democratic Republic of the Congo: a national cross-sectional study

BACKGROUND

Domesticated animal ownership is an understudied aspect of the human environment that influences mosquito biting behaviour and malaria transmission, and is a key part of national economies and livelihoods in malaria-endemic regions. In this study, we aimed to understand differences in Plasmodium falciparum prevalence by ownership status of common domesticated animals in DR Congo, where 12% of the world's malaria cases occur and anthropophilic Anopheles gambiae vectors predominate.

METHODS

In this cross-sectional study, we used survey data from individuals aged 15-59 years in the most recent (2013-14) DR Congo Demographic and Health Survey and previously performed Plasmodium quantitative real-time PCR (qPCR) to estimate P falciparum prevalence differences by household ownership of cattle; chickens; donkeys, horses, or mules; ducks; goats; sheep; and pigs. We used directed acyclic graphs to consider confounding by age, gender, wealth, modern housing, treated bednet use, agricultural land ownership, province, and rural location.

FINDINGS

Of 17 701 participants who had qPCR results and covariate data, 8917 (50·4%) of whom owned a domesticated animal, we observed large differences in malaria prevalence across types of animals owned in both crude and adjusted models. Household chicken ownership was associated with 3·9 (95% CI 0·6 to 7·1) more P falciparum infections per 100 people, whereas cattle ownership was associated with 9·6 (-15·8 to -3·5) fewer P falciparum infections per 100 people, even after accounting for bednet use, wealth, and housing structure.

INTERPRETATION

Our finding of a protective association conferred by cattle ownership suggests that zooprophylaxis interventions might have a role in DR Congo, possibly by drawing An gambiae feeding away from humans. Studies of animal husbandry practices and associated mosquito behaviours could reveal opportunities for new malaria interventions.

FUNDING

The National Institutes of Health and the Bill & Melinda Gates Foundation.

TRANSLATIONS

For the French and Lingala translations of the abstract see Supplementary Materials section.

Epidemiology of Plasmodium malariae and Plasmodium ovale spp. in a highly malaria-endemic country: a longitudinal cohort study in Kinshasa Province, Democratic Republic of Congo

Background

Increasing reports suggest that non-falciparum species are an underappreciated cause of malaria in sub-Saharan Africa, but their epidemiology is not well-defined. This is particularly true in regions of high P. falciparum endemicity such as the Democratic Republic of Congo (DRC), where 12% of the world's malaria cases and 13% of deaths occur.

Methods and Findings

The cumulative incidence and prevalence of P. malariae and P. ovale spp. infection detected by real-time PCR were estimated among children and adults within a longitudinal study conducted in seven rural, peri-urban, and urban sites from 2015-2017 in Kinshasa Province, DRC. Participants were sampled at biannual household survey visits (asymptomatic) and during routine health facility visits (symptomatic). Participant-level characteristics associated with non-falciparum infections were estimated for single- and mixed-species infections. Among 9,089 samples collected from 1,565 participants over a 3-year period, the incidence of P. malariae and P. ovale spp. infection was 11% (95% CI: 9%-12%) and 7% (95% CI: 5%-8%) by one year, respectively, compared to a 67% (95% CI: 64%-70%) one-year cumulative incidence of P. falciparum infection. Incidence continued to rise in the second year of follow-up, reaching 26% and 15% in school-age children (5-14yo) for P. malariae and P. ovale spp., respectively. Prevalence of P. malariae, P. ovale spp., and P. falciparum infections during household visits were 3% (95% CI: 3%-4%), 1% (95% CI: 1%-2%), and 35% (95% CI: 33%-36%), respectively. Non-falciparum malaria was more prevalent in rural and peri-urban vs. urban sites, in school-age children, and among those with P. falciparum co-infection. A crude association was detected between P. malariae and any anemia in the symptomatic clinic population, although this association did not hold when stratified by anemia severity. No crude associations were detected between non-falciparum infection and fever prevalence.

Conclusions

P. falciparum remains the primary driver of malaria morbidity and mortality in the DRC. However, non-falciparum species also pose an infection risk across sites of varying urbanicity and malaria endemicity within Kinshasa, DRC, particularly among children under 15 years of age. As P. falciparum interventions gain traction in high-burden settings like the DRC, continued surveillance and improved understanding of non-falciparum infections are warranted.