This analytical quantitative cross-sectional study on RSV prevalence and seasonality took part in five general hospitals and clinics in Kinshasa from DRC and aimed at determining the proportion of and seasonal factors influencing RSV in Kinshasa. Two hypotheses were raised; the first hypothesis stipulated that RSV presence in Kinshasa could be affected by socio-demographic characteristics such as gender, age and also severity of infection including hospitalization and the second hypothesis stipulated that RSV incidence could be different according to the rainy season and the dry season in Kinshasa. Both Hypotheses in this study were confirmed: RSV was mostly present during the rainy season and RSV was more prevalent in children age 0-2 years, more prevalent in women than in men and was more prevalent in SARI than in ILI samples. We found that many countries do not have data on RSV and therefore there is a need for data on the presence of RSV . This study tackled the prevalence using the variables gender, age, season and severity of infections. Statistical analysis using SPSS 25 was used to determine the association between the variables and the outcome which was rRt-PCR detection of RSV and also the likelihood of RSV infection.
This study showed that among inpatients and outpatients analyzed, 13.6% was positive for RSV which was close to the prevalence of RSV findings in other countries such as the following countries in Africa: Kenya 17%, South Africa 10.7%, Gambia 8.7%, Ghana 14.1%, Mozambique 9.8% and Burkina Faso 11.9% [15, 16, 17,18,19, 20]. In Madagascar, in an acute respiratory infection study done over one year the percentage of RSV positive was 11.8% .
These results can be representative of what is happening in the community of Kinshasa. Because of the small number of positives, the association between health facilities and RSV incidence was not checked nor taken in consideration.
In this study RSV was more prevalent in female than in male and at the same time it showed that females are more likely to be negative for RSV in Kinshasa. Other studies have shown that RSV was more predominant in male than in female whereby male were more affected . The difference in findings from other studies could be due to the fact that more female than male was part of this study population. Moreover, the statistical analysis showed that there was no statistically significant association between gender and the presence of RSV which correlated with many other studies around the world whereby RSV is more prevalent in one gender but the finding is not statistically significant [23, 24]. Many studies also failed to show or find a direct association between gender and RSV infection .
When it comes to age distribution of RSV, the virus occurrence and prevalence have demonstrated to be the same in all countries; it shows similarity in developed countries as well as developing countries [25, 22].
Nolan et al, 2015 found in her study on the prevalence of RSV that RSV prevalence declined as age decreased and that finding was the same in this study as the RSV positive samples were the least in adults and children older than 5 years of age and was more prevalent in children at the age of 2 and/or younger than 2 years. This study on RSV in Kinshasa had 18 positives in children age 0-2, 1 RSV positive in children 5-10, 2 RSV positive in age 10 to 25, and 2 RSV positive in age 40 and above which includes the elderly.
The findings from this study is similar to many studies whereby children under the age of 2 were less likely to be negative for RSV and had higher risks and chances of being infected by RSV, a few cases of RSV positives in elderly were found which also goes along with most reviews that also found sporadic cases of RSV infections in elderly. It is safe to say that the findings from this study correlated with many reviews and papers that looked at the association between age and RSV because this study also found a strong association p< 0.001 between age and RSV incidence in Kinshasa
Although this study findings showed that RSV was more present in samples of patients hospitalized with severe acute respiratory infection (60.9%) and less present in samples from patients that had influenza-like illness (39.1%) and that SARI patients are less likely to be negative for RSV, the statistical analysis showed that there was no statistically significant association between the severity of the infection and the presence or incidence of RSV.
This finding goes hand in hand with other literatures and studies done to find if there was an association between acute respiratory infection and RSV presence [27, 20, 28]. However, in a study on the prevalence of acute respiratory infection caused by RSV, findings showed that there was an independent association between RSV and the risk of developing an acute respiratory infection, but this specific study only included children younger than the age of 5 years old, had a larger number of study sample and was done on a shorter period of time (5 months), those differences could have favoured the difference in findings from that study and this study on RSV in Kinshasa .
RSV has shown to have seasonal outbreaks in many countries around the world, in countries with Mediterranean and temperate climate, RSV occurs during the relatively cold seasons, and in countries with tropical climates it occurs during the wet rainy season . Studies have shown that seasonal RSV occurred in phases where there was a shorter phase of seasonal RSV infection and a longer phase of seasonal RSV infection .
The DRC is a very large country, second largest in Africa after Algeria and is passed through by the Equator line; the country has a predominantly tropical climate with two rainy season peak that can go up to seven months . Parts of DRC that are located on the north of the country experience wet rainy season from the month of April to the month of November, wherever the regions located on the south of DRC experience rainy season from October to May. The province of Kinshasa from which the samples were collected is located on the south bank of DRC therefore experiences rainy season from October to May and dry season from June to September. The rainy season is relatively hot, wet and humid whereby the dry season is less hot and a tad cold and is considered the "cold season" with temperatures dropping to 20˚C and 17˚C at its lowest .
This study showed that RSV occurred predominantly 95.7% during the rainy season, which goes in accordance with most study findings on RSV seasonality for tropical climates. RSV incidence in this study decreased together with the temperature meaning the colder it got, the less RSV incidence occurred and this too was found in studies done in countries with similar climate to that of DRC. The cold or dry season in Kinshasa is holiday time and for 3 months straight all schools are closed, this can partially explain the decrease in RSV incidence as there might be lesser chances of contamination between children during that time since they do not attend school.