Geospatial and multilevel clustering of zero-dose children in Kikwit, Democratic Republic of the Congo in 2022

Zero-dose children remain highly vulnerable to vaccine-preventable diseases and can sustain transmission even in highly vaccinated populations. The WHO Immunization Agenda 2030 has prioritised reaching out to these children. We assessed the spatial distribution of zero-dose children together with the associated risk factors in a provincial capital in the Democratic Republic of Congo. A cross sectional survey was conducted in the city of Kikwit between September 28 and October 14, 2022. Data were collected both at household and health area level. QGIS and SATscan were used to describe and identify hotspots among zero-dose children, and a mixed effect logistic regression model was used to identify risk factors. Overall, 1,863 children aged 12-23 months were enrolled. Kikwit city had a 16.3% zero-dose prevalence, with significant variation between and within health zones. Two hotspots were identified through geospatial analysis, each spanning multiple health areas. Multilevel analysis revealed significant clustering at health area level and found six associated risk factors. These include the absence of home visits by community health workers (aOR = 1.90), living more than a kilometre from a health centre (aOR = 1.95), the mother's lack of tetanus vaccination (aOR = 3.16), and inability to name a vaccine-preventable disease (aOR = 3.20). However, secondary (aOR = 0.56) or tertiary (aOR = 0.21) education of mothers/guardians and belonging to Bunda (aOR = 0.36) or Mbala (aOR = 0.52) ethnicity reduced the risk of zero-dose. We observed a high prevalence of zero-dose children with a heterogeneous spatial distribution of epidemiological importance. Due to sub-zonal diversity, a health zone approach to reduce zero-dose immunization appears very limited. Zero-dose prevalence was related to the community health workers' home visit, to the distance of residence to a health centre and to household-level factors. Geospatial results could help in targeting priority health areas and communities for vaccination

Geospatial and age-related patterns of Taenia solium taeniasis in the rural health zone of Kimpese, Democratic Republic of Congo

Background: Taenia solium infections are mostly endemic in less developed countries where poor hygiene conditions and free-range pig management favor their transmission. Knowledge on patterns of infections in both human and pig is crucial to design effective control strategies. The aim of this study was to assess the prevalence, risk factors and spatial distribution of taeniasis in a rural area of the Democratic Republic of Congo (DRC), in the prospect of upcoming control activities. Methods: A cross-sectional study was conducted in 24 villages of the health zone of Kimpese, Bas Congo Province. Individual and household characteristics, including geographical coordinates were recorded. Stool samples were collected from willing participants and analyzed using the copro-antigen enzyme linked immunosorbent assay (copro-Ag ELISA) for the detection of taeniasis. Blood samples were collected from pigs and analyzed using the B158/660 monoclonal antibody-based antigen ELISA (sero-Ag ELISA) to detect porcine cysticercosis. Logistic regression and multilevel analysis were applied to identify risk factors. Global clustering and spatial correlation of taeniasis and porcine cysticercosis were assessed using K functions. Local clusters of both infections were identified using the Kulldorff s scan statistic. Results: A total of 4751 participants above 5 years of age (median: 23 years; IQR: 11-41) were included. The overall proportion of taeniasis positivity was 23.4% (95% CI: 22.2-24.6), ranging from 1 to 60% between villages, with a significant between-household variance of 2.43 (SE = 0.29, p < 0.05). Taeniasis was significantly associated with age (p < 0.05) and the highest positivity was found in the 5-10 years age group (27.0% (95% CI: 24.4-29.7)). Overall, 45.6% (95% CI: 40.2-51) of sampled pigs were sero-positive. The K functions revealed a significant overall clustering of human and pig infections but no spatial dependence between them. Two significant clusters of taeniasis (p<0.001; n = 276 and n = 9) and one cluster of porcine cysticercosis (p<0.001; n = 24) were found. Conclusion: This study confirms high endemicity and geographical dispersal of taeniasis in the study area. The role of age in taeniasis patterns and significant spatial clusters of both taeniasis and porcine cysticercosis were evidenced, though no spatial correlation was found between human and pig infections. Urgent control activities are needed for this endemic area

Molecular identification of Wolbachia and Sodalis glossinidius in the midgut of Glossina fuscipes quanzensis from the Democratic Republic of Congo

During the last 30 years, investigations on the microbiome of different tsetse species have generated substantial data on the bacterial flora of these cyclical vectors of African trypanosomes, with the overarching goal of improving the control of trypanosomiases. It is in this context that the presence of Wolbachia and Sodalis glossinidius was studied in wild populations of Glossina fuscipes quanzensis from the Democratic Republic of Congo. Tsetse flies were captured with pyramidal traps. Of the 700 Glossina f. quanzensis captured, 360 were dissected and their midguts collected and analyzed. Sodalis glossinidius and Wolbachia were identified by PCR. The Wolbachia-positive samples were genetically characterized with five molecular markers. PCR revealed 84.78% and 15.55% midguts infected by Wolbachia and S. glossinidius, respectively. The infection rates varied according to capture sites. Of the five molecular markers used to characterize Wolbachia, only the fructose bis-phosphate aldolase gene was amplified for about 60% of midguts previously found with Wolbachia infections. The sequencing results confirmed the presence of Wolbachia and revealed the presence of S. glossinidius in the midgut of Glossina f. quanzensis. A low level of midguts were naturally co-infected by both bacteria. The data generated in this study open a framework for investigations aimed at understanding the contribution of these symbiotic microorganisms to the vectorial competence of Glossina fuscipes quanzensis

Challenges in interpreting SARS-CoV-2 serological results in African countries

A diagnosis of COVID-19 is based on a positive PCR test for SARS-CoV-2. Over the past year, PCR testing capacity has varied globally due to the availability of tests, and testing strategies have targeted mainly symptomatic individuals. Therefore, the spread of the virus is probably wider than the numbers reported by official surveillance systems that are based on PCR results. Serology tests detect antibodies against SARS-CoV-2, which start being measurable around 1–2 weeks after infection. They are used in seroprevalence studies to estimate the proportion of people in a population that has been infected, including asymptomatic infection. These studies are of particular importance in African countries, where reported testing and incidence are among the lowest in the world.Peer Reviewe

Epidemiology of polyparasitism with schistosomes, Taenia solium and soil-transmitted helminths in co-endemic settings of the Democratic Republic of Congo

This thesis presents results of parasitological studies conducted in rural areas of western DRC. Findings indicate that single and co-infections with soil-transmitted helminths, schistosomes and taeniasis/cysticercosis are common and are heterogeneously distributed in space and within host populations. Co-endemicity of these helminth infections, similarities in age profiles and existence of shared risk factors between single and co-infections are suggestive of an integrated control approach. However, the use of praziquantel in an area potentially endemic for neurocysticercosis calls for more caution given the risk of severe neurological side effects. This thesis also shows that mixed Schistosoma infections alter the efficacy of single praziquantel treatment on S. haematobium though this short term effect disappears after cumulative treatments. All these findings can be useful to the design of an integrated control programme targeting many helminth infections at once.Cette thèse présente les résultats d'études parasitologiques menées dans les zones rurales de l'ouest de la RDC. Les résultats indiquent que les co-infections aux géohelminthes, schistosomes et le complexe téniase/cysticercose sont courantes et inégalement distribuées dans l'espace et au sein des populations hôtes. La co-endémicité de ces helminthiases, le jeune âge de la téniase et l'existence de facteurs de risque partagés entre les mono-infections et les co-infections suggèrent une approche de contrôle intégré. Cependant, l'utilisation du praziquantel dans une zone potentiellement endémique à la neurocysticercose nécessite plus de prudence compte tenu du risque d'effets secondaires neurologiques sévères. Cette thèse montre également que les infections mixtes à Schistosoma altèrent l'efficacité d’une dose unique de praziquantel sur S. haematobium, bien que cet effet à court terme disparaisse après des traitements cumulatifs. Ces résultats peuvent être utiles à la conception d'un contrôle intégré ciblant de nombreuses infections helminthiques à la fois(SP - Sciences de la santé publique) -- UCL, 201

Epidemiology of polyparasitism with schistosomes, Taenia solium and soil-transmitted helminths in co-endemic settings of the Democratic Republic of Congo

This thesis presents results of parasitological studies conducted in rural areas of western DRC. Findings indicate that single and co-infections with soil-transmitted helminths, schistosomes and taeniasis/cysticercosis are common and are heterogeneously distributed in space and within host populations. Co-endemicity of these helminth infections, similarities in age profiles and existence of shared risk factors between single and co-infections are suggestive of an integrated control approach. However, the use of praziquantel in an area potentially endemic for neurocysticercosis calls for more caution given the risk of severe neurological side effects. This thesis also shows that mixed Schistosoma infections alter the efficacy of single praziquantel treatment on S. haematobium though this short term effect disappears after cumulative treatments. All these findings can be useful to the design of an integrated control programme targeting many helminth infections at once.Cette thèse présente les résultats d'études parasitologiques menées dans les zones rurales de l'ouest de la RDC. Les résultats indiquent que les co-infections aux géohelminthes, schistosomes et le complexe téniase/cysticercose sont courantes et inégalement distribuées dans l'espace et au sein des populations hôtes. La co-endémicité de ces helminthiases, le jeune âge de la téniase et l'existence de facteurs de risque partagés entre les mono-infections et les co-infections suggèrent une approche de contrôle intégré. Cependant, l'utilisation du praziquantel dans une zone potentiellement endémique à la neurocysticercose nécessite plus de prudence compte tenu du risque d'effets secondaires neurologiques sévères. Cette thèse montre également que les infections mixtes à Schistosoma altèrent l'efficacité d’une dose unique de praziquantel sur S. haematobium, bien que cet effet à court terme disparaisse après des traitements cumulatifs. Ces résultats peuvent être utiles à la conception d'un contrôle intégré ciblant de nombreuses infections helminthiques à la fois(SP - Sciences de la santé publique) -- UCL, 201

Schistosomiasis in the Democratic Republic of Congo: a literature review

Schistosomiasis is a poverty-related parasitic infection, leading to chronic ill-health. For more than a century, schistosomiasis has been known to be endemic in certain provinces of the Democratic Republic of Congo (DRC). However, a clear overview on the status of the disease within the country is currently lacking, which is seriously hampering control. Here, we review the available information on schistosomiasis in DRC of the past 60 years. Findings and data gaps are discussed in the perspective of upcoming control activities.An electronic literature search via PubMed complemented by manual search of non-peer-reviewed articles was conducted up to January 2015. The search concerned all relevant records related to schistosomiasis in the DRC from January 1955 onwards. A total of 155 records were found, of which 30 met the inclusion criteria. Results were summarized by geographical region, mapped, and compared with those reported sixty years ago. The available data reported schistosomiasis in some areas located in 10 of the 11 provinces of DRC. Three species of Schistosoma were found: S. mansoni, S. haematobium and S. intercalatum. The prevalence of schistosomiasis varied greatly between regions and between villages, with high values of up to 95 % observed in some communities. The overall trend over 60 years points to the spread of schistosomiasis to formerly non-endemic areas. The prevalence of schistosomiasis has increased in rural endemic areas and decreased in urban/peri-urban endemic areas of Kinshasa. Hepatosplenomegaly, urinary tract lesions and anaemia were commonly reported in schistosomiasis endemic areas but not always associated with infection status.The present review confirms that schistosomiasis is still endemic in DRC. However, available data are scattered across time and space and studies lack methodological uniformity, hampering a reliable estimation of the current status of schistosomiasis in DRC. There is a clear need for updated prevalence data and well-designed studies on the epidemiology and transmission of schistosomiasis in DRC. This will aid the national control program to adequately design and implement strategies for sustainable and comprehensive control of schistosomiasis throughout the country

A QGIS-compatible geospatial file containing the results of geospatial analysis, which may be accessed using QGIS software.

A QGIS-compatible geospatial file containing the results of geospatial analysis, which may be accessed using QGIS software.</p

Household characteristics, Kikwit city, DRC, 2022 (n = 1863).

Household characteristics, Kikwit city, DRC, 2022 (n = 1863).</p

Molecular identification of

During the last 30 years, investigations on the microbiome of different tsetse species have generated substantial data on the bacterial flora of these cyclical vectors of African trypanosomes, with the overarching goal of improving the control of trypanosomiases. It is in this context that the presence of Wolbachia and Sodalis glossinidius was studied in wild populations of Glossina fuscipes quanzensis from the Democratic Republic of Congo. Tsetse flies were captured with pyramidal traps. Of the 700 Glossina f. quanzensis captured, 360 were dissected and their midguts collected and analyzed. Sodalis glossinidius and Wolbachia were identified by PCR. The Wolbachia-positive samples were genetically characterized with five molecular markers. PCR revealed 84.78% and 15.55% midguts infected by Wolbachia and S. glossinidius, respectively. The infection rates varied according to capture sites. Of the five molecular markers used to characterize Wolbachia, only the fructose bis-phosphate aldolase gene was amplified for about 60% of midguts previously found with Wolbachia infections. The sequencing results confirmed the presence of Wolbachia and revealed the presence of S. glossinidius in the midgut of Glossina f. quanzensis. A low level of midguts were naturally co-infected by both bacteria. The data generated in this study open a framework for investigations aimed at understanding the contribution of these symbiotic microorganisms to the vectorial competence of Glossina fuscipes quanzensis