Seroepidemiology of vaccine-preventable and emerging RNA viruses in Rwanda

Abstract Infectious diseases are a leading cause of death in sub-Saharan Africa, and in Rwanda diarrhea, lower respiratory and other common infections are linked to high mortality and morbidity. For children <5 years of age, neonatal/congenital disorders rank second among causes of death in Rwanda. However, neither the burden of, nor immunity to, fever-causing viruses in children and adults are currently known. Despite recent progress of vaccination in Rwanda, childhood infections including measles are regularly reported to WHO. To assess immunity to vaccine-preventable viruses, and susceptibility to emerging arboviruses, we investigated the seroprevalence by ELISA of IgG to MeV, RuV, ZIKV, CHIKV, and WNV on samples from Rwandan and Swedish blood donors collected during 2015 for comparative studies. The seroprevalence of MeV in Rwandan blood donors was low (71.5%) compared to that in Swedish donors (92.6%). This might be related to the previous one dose measles vaccine policy in Rwanda, (two doses were introduced in 2014). Yet, a comparably high seroprevalence was observed in older Rwandan and Swedish donors (90.4% versus 94.1%). The measles outbreak in Rwanda, 2010-2011, was investigated by PCR; sequencing revealed that these outbreak strains belonged to genotype B3, and were related to measles strains from neighboring countries. Rwandan blood donors were also tested for IgG to ZIKV and RuV, both viruses that can cause congenital infections. The ZIKV assay showed a seropositivity rate of 1.4%, and all 12 samples that were positive for anti-ZIKV IgG antibodies were negative by RT-PCR, arguing against active infection. Almost all women of childbearing age were found to be susceptible to ZIKV. In addition, a larger proportion of Rwandan women of childbearing age were seronegative for RuV (10.5%) compared to males (6.5%). Among Rwandan donors, anti-CHIKV IgG and anti-WNV IgG antibodies were detected at the rates of 63% and 10.4%, respectively. The highest seroprevalence for both viruses was recorded within the Eastern Province, with 86.7% and 33.3% for CHIKV and WNV IgG, respectively. Both Culex and Aedes mosquitos were most prevalent in the Eastern Province. Swedish blood donors, as expected, showed a much lower seroprevalence for CHIKV, 8.5%. Surprisingly, the seroprevalence for WNV in Swedish donors was relatively high, 14.1%. This stimulated investigation for possible serological cross-reactivity with another flavivirus circulating in Sweden, i.e. TBEV. Dual seroreactivities of 78.6% and 70.3% were observed to WNV and TBEV in Swedish and in Rwandan donors, respectively. Furthermore, 19 of the 28 Swedish sera seropositive to WNV were confirmed by plaque reduction neutralization test as being anti-TBEV IgG antibody-positive, with possible cross-reactivity to WNV. This dual seroreactivity to WNV and TBEV, seen in samples from both countries, was further characterised on pepscan analyses of E protein linear epitopes. Although we could define several novel IgG epitopes of both viruses, we found no explanation of their serological cross-reactivity. Instead, this phenomenon could be related to reactivity to discontinuous epitopes, or to IgG directed to flaviviral proteins other than the E protein. Surprisingly, the strongest peptide responses detected were from a pool of Rwandan plasma samples that reacted to linear epitopes of the E-protein of TBEV rather than WNV. This finding suggests the circulation of hitherto undiscovered tick-borne flaviviruses in Rwanda, which may share conserved epitopes with TBEV

Seroepidemiology of vaccine-preventable and emerging RNA viruses in Rwanda

Abstract Infectious diseases are a leading cause of death in sub-Saharan Africa, and in Rwanda diarrhea, lower respiratory and other common infections are linked to high mortality and morbidity. For children <5 years of age, neonatal/congenital disorders rank second among causes of death in Rwanda. However, neither the burden of, nor immunity to, fever-causing viruses in children and adults are currently known. Despite recent progress of vaccination in Rwanda, childhood infections including measles are regularly reported to WHO. To assess immunity to vaccine-preventable viruses, and susceptibility to emerging arboviruses, we investigated the seroprevalence by ELISA of IgG to MeV, RuV, ZIKV, CHIKV, and WNV on samples from Rwandan and Swedish blood donors collected during 2015 for comparative studies. The seroprevalence of MeV in Rwandan blood donors was low (71.5%) compared to that in Swedish donors (92.6%). This might be related to the previous one dose measles vaccine policy in Rwanda, (two doses were introduced in 2014). Yet, a comparably high seroprevalence was observed in older Rwandan and Swedish donors (90.4% versus 94.1%). The measles outbreak in Rwanda, 2010-2011, was investigated by PCR; sequencing revealed that these outbreak strains belonged to genotype B3, and were related to measles strains from neighboring countries. Rwandan blood donors were also tested for IgG to ZIKV and RuV, both viruses that can cause congenital infections. The ZIKV assay showed a seropositivity rate of 1.4%, and all 12 samples that were positive for anti-ZIKV IgG antibodies were negative by RT-PCR, arguing against active infection. Almost all women of childbearing age were found to be susceptible to ZIKV. In addition, a larger proportion of Rwandan women of childbearing age were seronegative for RuV (10.5%) compared to males (6.5%). Among Rwandan donors, anti-CHIKV IgG and anti-WNV IgG antibodies were detected at the rates of 63% and 10.4%, respectively. The highest seroprevalence for both viruses was recorded within the Eastern Province, with 86.7% and 33.3% for CHIKV and WNV IgG, respectively. Both Culex and Aedes mosquitos were most prevalent in the Eastern Province. Swedish blood donors, as expected, showed a much lower seroprevalence for CHIKV, 8.5%. Surprisingly, the seroprevalence for WNV in Swedish donors was relatively high, 14.1%. This stimulated investigation for possible serological cross-reactivity with another flavivirus circulating in Sweden, i.e. TBEV. Dual seroreactivities of 78.6% and 70.3% were observed to WNV and TBEV in Swedish and in Rwandan donors, respectively. Furthermore, 19 of the 28 Swedish sera seropositive to WNV were confirmed by plaque reduction neutralization test as being anti-TBEV IgG antibody-positive, with possible cross-reactivity to WNV. This dual seroreactivity to WNV and TBEV, seen in samples from both countries, was further characterised on pepscan analyses of E protein linear epitopes. Although we could define several novel IgG epitopes of both viruses, we found no explanation of their serological cross-reactivity. Instead, this phenomenon could be related to reactivity to discontinuous epitopes, or to IgG directed to flaviviral proteins other than the E protein. Surprisingly, the strongest peptide responses detected were from a pool of Rwandan plasma samples that reacted to linear epitopes of the E-protein of TBEV rather than WNV. This finding suggests the circulation of hitherto undiscovered tick-borne flaviviruses in Rwanda, which may share conserved epitopes with TBEV

Arbovirus surveillance in febrile patients attending selected health facilities in Rwanda

Arthropod-borne (arbo) viruses cause emerging diseases that affect the livelihoods of people around the world. They are linked to disease outbreaks resulting in high morbidity, mortality, and economic loss. In sub-Saharan Africa, numerous arbovirus outbreaks have been documented, but the circulation and magnitude of illness caused by these viruses during inter-epidemic periods remains unknown in many regions. In Rwanda, there is limited knowledge on the presence and distribution of arboviruses. This study aimed at determining the occurrence and distribution of selected arboviruses, i.e., chikungunya virus (CHIKV), o’nyong-nyong virus (ONNV), dengue virus (DENV), West Nile virus (WNV), Zika virus (ZIKV), Rift Valley fever virus (RVFV) and Crimean-Congo haemorrhagic fever virus (CCHFV), among febrile patients visiting health centres in Rwanda. A total of 2294 dry blood spots (DBS) were collected on filter papers during August 2019 – December 2020. Reverse-transcription polymerase chain reaction (RT-PCR) was performed on samples in pools of ten, using both quantitative (DENV, ZIKV, RVFV) and conventional PCR (CHIKV, ONNV, WNV, CCHFV) with virus specific primers, followed by sequencing. Demographic data and clinical manifestations of illness were analysed. ONNV infection was detected in 12 of 230 pools (5.2%) and ZIKV in three pools (1.3%). The other arboviruses were not detected. All ONNV cases were found in the Rwaniro health centre, while ZIKV infection was found among patients visiting the Kirinda and Zaza health centres. There was temporal variability in ONNV infections with most cases being recorded during the long dry season, while ZIKV infection occurred during both dry and wet seasons. Patients with ONNV were older and more were females. In conclusion, ONNV and ZIKV infection were detected in acute patients and can explain some of the feverish diseases in Rwanda.Originally included in thesis in manuscript form. </p

Hepatitis B vaccination coverage among healthcare workers at a tertiary hospital in Rwanda

Abstract Objective We evaluated post-vaccination immunity status and describe potential risk factors associated with the lack of response among healthcare workers (HCWs) at a tertiary care hospital in Kigali, Rwanda. Results Of 373 HCWs, 291 (78.2%) were female and 81 (21.8%) were male. The mean age of the study participants was 40.2 years (standard deviation [SD], 7.7 years), within a range of 24–41 years. Participants’ mean BMI was 25.4 ± 6.6 kg/m2, with more than half of patients (60.3%) being overweight. 96% received all three doses of vaccination. A total of 36 participants (9.6%) were considered non responders as they did not develop a sufficient anti-HBs response post vaccination. The anti-HBs response was significantly higher in females when compared to males (p = 0.02). Interestingly, there was no significant association between decline in antibody levels with age (p = 0.242) and BMI (p = 0.516) of the participants. The anti-HBs titers were similar in the group of participants who had received two doses and those who had received three doses of the HBV vaccination. Overall the findings of our study provide a basis for testing for anti-HBs in all HCWs post vaccination in Rwanda