October 20, 2022
Announcing the Outbreak:
- On August 30, 2022, Mauritanian Ministry of Health notified World Health Organization of an outbreak of Rift Valley Fever (RVF) after laboratory confirmation of the case.
- The case was a 25-year-old male who was a cattle rancher from Tintane County, Western Basin State, reported to a health center on 25 August with hemorrhagic syndrome (epistaxis) and severe thrombocytopenia and was transferred the next day to a regional hospital where he died two days later on 29 August.
- On October 17, 2022, a total of 47 confirmed cases were reported, including 23 deaths, mostly among livestock farmers from nine out of 15 states in Mauritania. Majority of cases are men and average age is 22 years.
Rift Valley Fever:
RVF is primarily an animal disease due to acute hemorrhagic fever that occurs most commonly in domestic animals (e.g. cattle, buffaloes, sheep, goats, and camels) and can also be transmitted to humans. The disease is caused by the Rift Valley Fever virus (RVFV), member of the genus Venous viruses of the order Buniavirales.
History of the outbreak:
- Rift Valley Fever was first reported in cattle by veterinarians in Kenya Rift Valley in the early 2000s and this is the reason for the name. It is generally found in eastern and southern Africa where sheep and cattle are raised, but it is found in most regions of sub-Saharan Africa, including West Africa and Madagascar.
- In September 2000, an outbreak of Rift Valley Fever was reported in southern Saudi Arabia and in Yemen as well. This was the first case of RVF identified outside Africa.
- The outbreak of Rift Valley Fever virus has recurred in Mauritania, where the country witnessed previous outbreaks in 1987, 2010, 2012, 2015 and 2020.
Disease Transmission:
- The virus is transmitted mainly from an infected animal or person through mosquito bites (Aedes aegypti and colix mosquitoes). Heavy rains also help hatch eggs of mosquitoes carrying the virus, as the virus remains alive in eggs throughout dry periods.
- Contact with blood, body fluids or tissues of infected animals, especially livestock such as sheep, goats, buffaloes and camels.
- Eating raw meat and unpasteurized or uncooked milk of infected animals.
- Direct human-to-human transmission of RVF has not been documented.
Symptoms and Diagnosis:
Symptoms in humans range from mild flu-like to severe hemorrhagic fever that can be fatal. Most people with RVF either have no symptoms or have mild illness (fever, weakness, back pain, dizziness). However, a small percentage (8-10%) of people with RVF develop severe acute symptoms, including eye disease, bleeding, and encephalitis (brain swelling).
In animals: Fever, weakness, abortion and high death rate, especially among young animals.
Clinical diagnosis is difficult because symptoms can be mild and nonspecific. The virus can be detected in blood and tissues by RT-PCR.
Treatment:
There are no specific approved treatments for RVF because most cases are mild and symptoms such as fever and body aches can be controlled with over-the-counter medications.
Public Health Response:
- Establishing a committee at the national level to coordinate between human and animal health sectors.
- Strengthening diagnostic and management capacities, active case search and provision of medicines and personal protective equipment to health facilities in affected areas.
- Awareness of affected communities, especially populations at risk (livestock farmers and butchers), about preventive measures and what to do in case of abortion, death of livestock, or hemorrhagic syndrome in a person.
Protection:
- Spreading awareness through media campaigns about risk factors for transmission of RVF, and preventive measures such as:
- Safer animal husbandry and slaughter practices, including practicing hand hygiene, wearing gloves and other personal protective equipment.
- Carefully cook all animal products (blood, meat, milk) before taking them.
- Mosquito control (such as eliminating larvae at breeding sites), using insecticide-treated bed nets and repellents, wearing light-colored clothing and avoiding outdoor activities during times when the vector species is most active.
- Restricting or banning movement of livestock to limit spread of the virus from infected to uninfected areas.
- Animal vaccination: Because RVF animal epidemics precede human cases, an effective animal health surveillance system is essential to provide early warning to veterinary and human public health authorities.
- Healthcare Providers: Healthcare workers who encounter suspected or confirmed cases of RVF should apply standard precautions when handling samples from their patients.
Risk Assessment:
Frequent cross-border grazing movements increase risks of regional spread of the disease to neighboring countries and RVF is not among the diseases controlled by livestock vaccination at the border.
World Health Organization (WHO) advises no restrictions on travel or trade to Mauritania or the affected areas, based on information currently available on this event.
Sources:
- WHO
- Center for Disease Control and Prevention CDC