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Published on: January 28, 2019
Epidemiological trends of diarrheal viruses in central and western Kenya before and after Rotavirus vaccine
Maurine Mumo Mutua1,2, Cyrus Kathiiko1, Mary N Wachira1
1Institute of Tropical Medicine, Nagasaki University-Kenya Medical Research Institute, Nairobi, Kenya.
Insights
Rotavirus vaccination in Kenya did not significantly alter norovirus or astrovirus prevalence in young children. Adenovirus trends varied regionally, highlighting the need for ongoing surveillance of enteric viruses.
Area of Science:
- Pediatric infectious diseases
- Virology
- Epidemiology
Background:
- Rotavirus, norovirus, adenovirus, and astrovirus are key causes of acute gastroenteritis in children globally.
- Kenya implemented rotavirus vaccination in July 2014, leading to a noted decrease in rotavirus prevalence.
- The study investigates the impact of rotavirus vaccination on other enteric virus epidemiology in Kenya.
Purpose of the Study:
- To assess the effect of rotavirus vaccine introduction on the prevalence and epidemiological trends of adenovirus, astrovirus, and norovirus in Kenyan children.
- To compare viral gastroenteritis patterns before and after the national rotavirus vaccination program.
Main Methods:
- Analysis of 716 fecal samples from children under 5 with acute gastroenteritis, negative for rotavirus.
- Samples were collected from Western and Central Kenya before (2011-2013) and after (2019-2020) rotavirus vaccine introduction.
- Conventional and multiplex RT-PCR were used to detect adenovirus, astrovirus, and norovirus.
Main Results:
- Norovirus and astrovirus prevalence showed no significant change post-vaccination in either region.
- Adenovirus prevalence increased in Western Kenya but significantly decreased in Central Kenya.
- Age-specific patterns for adenovirus and norovirus shifted post-vaccination, indicating altered epidemiological dynamics.
Conclusions:
- Rotavirus vaccination has not significantly impacted the prevalence of norovirus and astrovirus in the studied regions.
- Regional variations in adenovirus epidemiology were observed post-vaccination.
- Continuous monitoring of enteric virus epidemiology is crucial for effective public health interventions in Kenya.
Background:
Rotavirus, norovirus, adenovirus (type 40/41) and astrovirus are the most significant viral etiological agents of acute gastroenteritis in young children globally. Kenya introduced the rotavirus vaccine into her National Immunization Program in July 2014, which has led to a significant decline in the prevalence of rotavirus. We sought to assess the impact of rotavirus vaccination on the epidemiological trends of other diarrhea-associated enteric viruses across different regions in Kenya.
Methodology:
Using conventional and multiplex RT-PCR, we analyzed a total of 716 fecal samples for adenovirus, astrovirus and norovirus from children aged below 5 years presenting with acute gastroenteritis but tested negative for rotavirus at Mbita Sub-County Referral Hospital in Western Kenya and Kiambu County Referral Hospital in Central Kenya before (2011-2013) and after (2019-2020) rotavirus vaccine introduction.
Results:
Following the rotavirus vaccine introduction, there was no significant difference in norovirus and astrovirus prevalence post-vaccine introduction in both Central (norovirus- 5.4% vs 5.9%; astrovirus- 2% vs 2.4%) and Western Kenya (norovirus- 2% vs 3%; astrovirus 3.3% vs 5.9%). Although the prevalence of adenovirus increased substantially in Western Kenya (9% vs 12.4%), there was a significant decrease in adenovirus in Central Kenya (17%, vs 6%, p = 0.007). Before the introduction of the rotavirus vaccine, a large proportion of adenovirus cases occurred at 6-8 months in Central Kenya and 12-23 months in Western Kenya, while norovirus prevalence was highest at 12-23 months in Central and 3-5 months in Western Kenya. Astrovirus infections in Central Kenya were predominantly among children aged 12-23 months, both before and after the vaccine. Following vaccine introduction, a large proportion of adenovirus cases occurred among children aged 12-23 months in both regions. Norovirus peaked at 12-23 months in Central Kenya and showed dual peaks at 3-5 and 9-11 months in Western Kenya. Astrovirus infections in Western Kenya shifted from peaks at 6-8 and 24-59 months pre-vaccine to 9-11 months post-vaccine.
Conclusion:
Our data demonstrate the burden and changing epidemiology of enteric viruses in Western and Central Kenya and underscores the need for continued monitoring to guide the design and implementation of appropriate public health interventions.
