Rift Valley Fever Virus Infectivity in Milk Stored at a Wide Range of Temperatures

Area of Science:

• Veterinary Virology
• Food Safety
• Public Health

Background:

• Rift Valley fever virus (RVFV) is a zoonotic arbovirus causing epidemics in Africa and the Arabian Peninsula.
• Human exposure occurs through mosquito bites or direct contact with infected livestock, including milk consumption.
• The stability of infectious RVFV in milk has not been previously studied.

Purpose of the Study:

• To assess the stability of infectious Rift Valley fever virus (RVFV) in milk.
• To determine the impact of temperature on RVFV stability in milk.
• To evaluate the efficacy of common milk processing methods in inactivating RVFV.

Main Methods:

• Cow and goat milk were spiked with the RVFV-MP12 vaccine strain.
• Viral RNA levels were quantified using qRT-PCR.
• Infectious viral titers were measured via plaque assay at various temperatures over time.

Main Results:

• RVFV remained stable in refrigerated milk for up to 96 hours.
• Infectious RVFV persisted in milk at warm ambient temperatures for up to two days.
• RVFV RNA was detectable by qRT-PCR in milk for up to 96 hours across all tested temperatures.
• Standard pasteurization and boiling completely inactivated RVFV in milk.

Conclusions:

• Contaminated milk in endemic regions poses a significant public health risk.
• Pasteurization is an effective method to mitigate RVFV transmission through milk.
• RVFV RNA detection in milk offers a non-invasive surveillance strategy for the virus.