FACULTY OF MEDICINE

DEPARTMENT OF MEDICAL BIOLGY

Thesis presented and publicly defended with a view to obtaining the title of Associate Professor of Higher Education in Medicine

By

Edith NKWEMBE NGABANA

Doctor of Medicine

Specialist in Medical Biology, Option: Microbiology

Works Manager

Promoter: Prof. Dr. Jean-Jacques MUYEMBE TAMFUM, MD, Ph.D.

Co-Promoters: – Prof. Dr. Emile OKITOLONDA WEMAKOY, MD, Ph.D. – Prof. Dr. Steve AHUKA MUNDEKE, MD, Ph.D.

JANUARY 2023

SUMMARY

Context

Influenza is poorly documented in the Democratic Republic of Congo (DRC), where several epidemics can go unnoticed. The only epidemic investigation reports available in the country do not allow for an estimate of the true extent and epidemiology of influenza. This thesis aims to contribute to the understanding of influenza in Kinshasa.

Objective

Contribute to improving our knowledge of influenza viruses and their molecular epidemiology in Kinshasa.

Methods

Three descriptive studies were conducted in Kinshasa between 2009 and 2014. The first was based on a literature review of articles and archives on ARI and/or influenza in the DRC; the second and third were based on sentinel influenza surveillance. For the last two studies, oro- and nasopharyngeal secretions from suspected patients seen as outpatients or inpatients were collected, stored and then transported to the National Institute of Biomedical Research (INRB). The search for influenza A and B viruses was performed by real-time retro transcription polymerase chain reaction (RT-qPCR), following the CDC/Atlanta protocol, followed by molecular characterization.

Results

For the first study, four epidemic reports were found between 1995 and 2007, mainly in the western part of the country (Bandundu, Equateur and Kinshasa) showing attack rates (AT) and case fatality rates (TL) of 3.9-47.5 % and 2-16 % respectively. Children under 5 years were the most affected with high morbidity and mortality: 22.6-57.7 %) and (TL: 3.2-3.7 %).

Furthermore, 11,456 samples were taken from 7,453 (65.1 %) patients seen as outpatients and 4,003 (34.9 %) inpatients. One thousand one hundred and forty-seven samples (10.1 %) were positive for influenza viruses. Among them, 11.45 % from outpatients (n=850) and 7.46 % from inpatients (n=297) of whom children under 5 years of age were the most affected in both types of influenza, both in outpatients (64.1%- 59.7 %) and inpatients (35.9%- 40.3 %).

Influenza A viruses were detected at 68.5 TP3T (n=786) followed by influenza B viruses at 30.8 TP3T (n=354). Among the influenza A viruses, 37.5 TP3T were of H3N2 subtype and 25.5 TP3T of HlN1. All these influenza viruses (type and subtypes) co-circulated during all these years with variable predominance of one influenza virus subtype over the others depending on the seasons.

Two peaks of intense influenza activity were identified from January to May and from October to December between 2009 and 2014, marking the seasonality of influenza in Kinshasa, coinciding with the rainy season.

Phylogenetic analysis showed genetic diversity of influenza A/H3N2 and B/Yamagata viruses, consistent with the corresponding vaccine strains validated by WHO; and sensitive to standard antivirals.

Conclusion

The data in this thesis document the extent of virus infection in Kinshasa, its seasonality and its evolution in mutational drift, essential for the implementation of strategies to fight and control influenza in Kinshasa.

Keywords: Influenza viruses, Surveillance, Kinshasa