Health: At least 13 people in Kenya have been killed after an outbreak of Rift Valley fever (RVF). Around 234 human cases have been reported in Kenya, with cases of infected livestock also reported in Kenya and nearby Rwanda; Tanzania is on alert for a potential outbreak. Wajir county has been most impacted by the disease in Kenya, with the first fatality of the current outbreak reported on 02 June. Further outbreaks have also reported in Badanrero, Amballo, Ittir, Kargi, Olturot, Loglogo, Korr, Laisamis, North Horr, Balesa, Demo, Shuur and Maikon. While one death has also been reported in Siaya county. In Rwanda, livestock in Ngoma, Kirehe, and Kayonza districts has been placed under quarantine.
What is Rift Valley Fever?
Rift Valley fever is an acute, mosquito-borne, fever-causing viral disease which is most commonly found in domesticated animals such as cattle and sheep. It has the potential to infect and cause illness in humans, most commonly contracting the disease through contact with blood or organs of infected animals but may also be transmitted through the bites of infected mosquitoes. No human-to-human transmission, nor urban outbreaks, have ever been reported. Reports also suggest that humans may contract the disease through unpasteurised/uncooked milk. It is named after where it was first located – the Rift Valley, Kenya in 1931.
In animals, abortion, haemorrhage, and fever are among the signs of RVF, notably in sheep and camels. In humans, the incubation period varies from two to six days, and symptoms usually last for four to seven days. Those infected usually work with animals including herders, farmers, and veterinarians. Most of those infected will show mild symptoms, usually consisting of flu-like conditions (vomiting, muscle pain, migraine, sensitivity to light etc.) and is often confused with meningitis.
In more severe cases, RVF can cause one or more of these three symptoms:
Ocular form: In this form of RVF, the milder symptoms are accompanied by retinal lesions. The onset of the lesions usually occurs one to three weeks after display of the first symptoms. Patients usually report obstructed vision. The symptoms may be resolved with no long-term effects within 10 to 12 weeks. However, when the lesions occur in the macula, 50 per cent of patients will experience permanent blindness. Those contracting the ocular form only rarely face death.
Meningoencephalitis form: This form of the disease usually occurs one to four weeks after the first symptoms appear. Symptoms include an intense headache, loss of memory, hallucinations, confusion, disorientation, vertigo, lethargy, and coma. Neurological complications may appear later (after more than 60 days). The death rate in patients who experience only this form of the disease is low, although possibly severe residual neurological deficit, is common.
Haemorrhagic fever form: Symptoms of this form of the disease appear two to four days after the onset of illness, beginning with of severe liver impairment, such as jaundice. Subsequent symptoms include vomiting blood, passing blood in the faeces, a purpuric rash (caused by bleeding in the skin), bleeding from the nose or gums, and abnormal bleeding during menstruation. The fatality rate for those contracting this form of RVF is around 50 per cent, with death usually occurring three to six days after symptoms initially occur.
Diagnosis and Treatment
It is of note that RVF, with its varied symptoms, can be difficult to clinically diagnose, especially in the early stages of infection. At times it has been confused with Ebola, yellow fever, and meningitis, due to the similar symptoms.
Treatment generally consists of supportive treatments aimed at limiting the symptoms of the disease rather than targeting the disease itself. There is no licensed vaccine at present, though an experimental one has been tested on veterinary and laboratory staff who may be at high risk for contracting RVF.
The WHO advises that outbreaks can be prevented by a sustained campaign of animal vaccination
Rift Valley fever is not uncommon in Kenya or East Africa. The last significant outbreak in Kenya was reported from November 2014 and January 2015. In 2006, an outbreak caused the death of hundreds in the region. Most outbreaks have been consigned to sub-Saharan Africa. However, Rift Valley fever was reported in Egypt in 1971 (attributed to livestock trade along the River Nile). An outbreak in Saudi Arabia and Yemen in 2000 raised fears that the disease would spread to Europe and further afield.
Severe outbreaks of RVF since 2000:
2016 – The Niger Ministry of Health reported 105 suspected cases including 28 deaths of RVF in humans in the Tahoua region.
2012 –The Ministry of Health in Mauritania reported an outbreak of the disease in October 2012. A total of 36 cases, including 18 deaths were reported from six regions.
2010 – From February to July 2010, the Government of South Africa reported 26 fatalities from 237 confirmed human cases of RVF from nine provinces.
2008–2009 – From December 2008 to May 2009, Madagascar’s health ministry reported 236 suspected cases including seven deaths.
2008 – The Ministry of Health, Madagascar reported an outbreak of RVF in April 2008. Between January and June 2008, a total of 476 suspected cases of RVF and 19 deaths were reported in provinces.
2007: Sudan’s health ministry reported a total of 738 cases, including 230 deaths during an RVF outbreak.
2006-2007: From November 2006 to March 2007, a total of 684 cases including 234 deaths from RVF were reported in Kenya. From December to February, a total of 114 cases including 51 deaths were reported in Somalia. From January to May 2007, a total of 264 cases including 109 deaths were reported in Tanzania.
2003: Egyptian authorities reported 148 cases including 27 deaths of RVF.
2000: There were 516 cases of RVF with 87 deaths reported by the Ministry of Health of Saudi Arabia. While in Yemen, 1087 suspected cases, including 121 deaths, were reported.
Why the Increase in Cases?
The outbreak has been blamed on prolonged rains leading to heavy flooding and stagnant waters, which creates a conducive breeding environment for the Aedes and Culex mosquitoes, the main vectors for transmission of the disease. Infected areas also generally suffer from lower levels of safe animal husbandry and meat production consumption education. The impacted areas are also served by poor levels of health and governmental infrastructure.
What is Being Done?
Kenyan health authorities have been preparing for a potential outbreak since February 2018 in reaction to heavy rain and flooding.
14 June – Health officials initiated the Emergency Operations Centre, with a supporting technical team.
14 June – A multi-sectoral investigation team was deployed to Wajir County in support of the county health teams. In Wajir County, five treatment centres have been established.
08 June – The Ministries of Health and Agriculture convened an emergency meeting with the Ministry of Livestock and other key officials. A health sector task force meeting was held, with partners pledging to Rift Valley fever control.
Residents in areas where Rift Valley fever have been reported have been advised to eat inspected and thoroughly cooked meat products only. A ban on slaughtering animals and restriction of livestock movement has been implemented in affected areas. This message is being disseminated through community health volunteers. There has been a strengthening of surveillance for Rift Valley fever in affected and at-risk counties.