# Rift Valley Fever Outbreak Investigation Associated with a Dairy Farm Abortion Storm, Mbarara District, Western Uganda, 2023

## TL;DR

A 2023 Rift Valley Fever outbreak in Uganda was linked to a dairy farm abortion storm and human cases, highlighting the need for better control and education.

## Contribution

This study reports a unique RVF outbreak in Uganda with direct links between animal abortions and human infections.

## Key findings

- Thirteen human RVF cases and nine PCR-positive animals were directly linked to the abortion storm.
- 61 human RVFV cases were confirmed in Uganda in 2023, with 88.5% having contact with livestock.
- The case fatality rate was 31%, emphasizing the severity of the outbreak.

## Abstract

In Africa, Rift Valley Fever poses a substantial risk to animal health, and human cases occur after contact with infected animals or their tissues. RVF has re-emerged in Uganda after nearly five decades, with multiple outbreaks recorded since 2016. We investigated a unique RVF outbreak associated with an animal abortion storm of 30 events and human cases on a dairy farm in Mbarara District, Western Uganda, in February 2023. Genomic analysis was performed, comparing animal and human RVF viruses (RVFV) circulating in the region. A cluster of thirteen human RVF cases and nine PCR-positive animals could directly be linked with the abortion storm. Overall, during the year 2023, we confirmed 61 human RVFV cases across Uganda, 88.5% of which were reported to have had direct contact with livestock, and a high case fatality rate of 31%. We recommend implementing extensive health education programs in affected communities and using sustainable mosquito control strategies to limit transmission in livestock, coupled with initiating animal vaccination trials in Uganda.