Rift Valley fever outbreak among animal handlers in Kinyogoga Village, Nakaseke District, Central Uganda: A case study

Abstract

Rift Valley fever (RVF) is a viral zoonosis which occurs sporadically in Uganda. On July 24, 2023, a 24-year-old male animal husbandry officer from Nakaseke District presented to a hospital in Kampala District with history of intermittent nosebleeds. He tested positive for Rift Valley fever virus (RVFV) by reverse transcriptase polymerase chain reaction (RT-PCR). We investigated to identify the source, estimate the magnitude, and determine the drivers of the outbreak, in order to inform control measures. We defined a suspected case as a sudden onset of fever (≥38°C) and ≥2 of: headache, skin rash, muscle/joint pain, intense fatigue, dizziness, coughing, abdominal pain, or unexplained bleeding from any site in a resident of Kinyogoga Village, Nakaseke District from June 1-July 30, 2023. A confirmed case was a suspected case with positive RT-PCR for RVFV. We conducted active case finding, environmental assessments, interviewed secondary cases and the family members of the deceased index case, and collected blood samples for testing. We identified eight case-patients, all males and one died. Median age for both the suspected and confirmed case-patients was 25 years (range: 19-28). Symptoms included: high fever (100%), headache (100%), vomiting blood and nose bleeding (25%). The case-patients identified (one animal husbandry officer and seven herders) worked on three affected farms that had recently recorded high rates of abortion and mortality in cattle and shoats. The index case started vomiting blood on July 19, 2023; RVF was confirmed five days later. Prior to that, he had visited three health facilities within the outbreak area that clinically diagnosed brucellosis, typhoid and gastritis. This RVF outbreak likely resulted from contact with infected livestock and their products. We recommend training healthcare workers, animal health workers and animal handlers on RVF, strengthening surveillance, vaccinating livestock, implementing mosquito control measures and conducting community education.

Fig 1. Location of Kinyogoga Village in Kinyogoga Subcounty, Nakaseke District, Uganda.

Fig 2. Symptoms presentation of case-patients during Rift Valley fever outbreak in Nakaseke District, Uganda, June–July 2023.

Fig 3. Map of Nakaseke showing location of farms affected by Rift Valley fever (red dots) in Kinyogoga Village, Kinyogoga Subcounty, June–July 2023.

Fig 4. Distribution of symptom onset dates of Rift Valley fever case-patients: Nakaseke District, Uganda, June-July 2023.