Outbreak Summaries

2016 – present – Uganda

In March 2016, a male butcher from Kabale District in western Uganda reported to a local hospital with symptoms of headache, fever, fatigue and bleeding, subsequently testing positive for Rift Valley Fever (RVF). CDC sent epidemiologists to the District to assist the Ugandan Ministry of Health with the epidemiologic investigation of this small, localized outbreak of 3 confirmed and 2 probable cases. Working with the Uganda Virus Research Institute (UVRI) and the Uganda Ministry of Health, the CDC team conducted a serologic study in animals and humans and also assessed residents’ knowledge, attitudes, and practices related to RVF. The team collected samples from cows, goats and sheep, and interviewed and tested 650 district residents. A coordinated educational campaign targeting the general population, farmers, herders, and butchers was initiated and informational posters were created targeting these groups. This was the first identification of RVFV in Uganda in 48 years; since that time, at least 10 subsequent outbreaks have been identified in Uganda. Rapid case detection, prompt laboratory testing at UVRI, and presence of pre-trained, well-prepared rapid response teams facilitated rapid containment and control of these outbreaks.

References:
Shoemaker et al. First laboratory-confirmed outbreak of human and animal Rift Valley fever virus in Uganda in 48 years. Am. J. Trop. Med. Hyg., 100 (3) (2019), pp. 659-671external icon

Nyakarahuka et al. Ten outbreaks of rift valley fever in Uganda 2016-2018: epidemiological and laboratory findings. Intl J of Infectious Diseases. 79 (4) (2019)external icon

WHO AFRO Weekly Bulletin on Outbreaks, Week 52 (29 December 2019) pdf icon[PDF – 2.68MB]external icon

2019 – Mayotte (France)

In January 2019, France informed WHO of five human cases of RVF diagnosed on Mayotte Island through the Early Warning and Response System of the European Union with symptom onset dates from November to December 2018. From November 2018 to May 2019, 129 confirmed human RVF cases and 109 animal foci were reported in Mayotte. Both human RVF cases and animal foci were mainly located in the center and the north west of the main island Grande-Terre, although late in the outbreak (from the end of March through May 2019), a few animal foci were also detected in the east of Grande-Terre and in Petite Terre of Mayotte.

WHO Disease Outbreak News, 13 May 2019. Rift Valley fever in Mayotteexternal icon

2018 – Kenya

In June 2018, the Ministry of Health for Kenya confirmed an outbreak of RVF. A total of 26 human cases were reported from Wajir (24 cases, including the first patient) and Marsabit (2 cases) counties, including seven confirmed cases and six deaths (case fatality ratio (CFR) = 23%). A high number of deaths and abortions among livestock, including camels and goats, were reported in Garissa, Kadjiado, Kitui, Marsabit, Tana River, and Wajir counties. People living in these counties were reportedly consuming meat from dead and sick animals.

WHO Disease Outbreak News, 18 June 2018. Rift Valley fever in Kenyaexternal icon

2017 – Gambia (reported by Senegal)

In January 2018, the Ministry of Health of Senegal notified WHO of a case of RVF in a resident of Gambia who had been medically evacuated to Dakar, Senegal. The patient developed symptoms on December 10, 2017 while in Guinea Bissau, returned to Banjul, Gambia, was medically evacuated December 25, and died on December 31. A blood sample from the case was tested at the Institute Pasteur in Dakar and was positive for IgM against RVF virus.

WHO Disease Outbreak News, 26 February 2018. Rift Valley fever in Gambiaexternal icon

2016 – Angola (reported by China)

WHO Disease In July 2016, the National IHR Focal Point of China notified WHO of an imported case of RVF. The patient had been working in Luanda, Angola. No history of travel outside Luanda had been reported. The patient had onset of symptoms in Angola and sought medical treatment in a hospital in Angola, but returned to China shortly thereafter. A sample from the case tested positive for RVF at the Beijing Municipal Center for Disease Prevention and Control (Beijing CDC) and was confirmed on the same day at the China Center for Disease Prevention and Control (China CDC).

Outbreak News, 2 August 2016. Rift Valley fever in Chinaexternal icon

2016 – Niger

In late August of 2016, health authorities in Niger’s Tahoua region reported cases of febrile illness, including hemorrhagic symptoms, in humans, as well sickness and abortions in ruminants. Subsequent diagnostic testing at the Institut Pasteur in Dakar, Senegal confirmed RVF. As of December 5, 2016, the WHO Niger Country Office reported a total of 348 cases of RVF in humans (17 of which were laboratory confirmed), with 33 deaths. No data are available on the animal morbidity and mortality due to RVF.

Staff from the Ministry of Public Health, the Ministry of Agriculture/Livestock, the World Health Organization (WHO), the Food and Agricultural Organization (FAO), the World Organization for Animal Health (OIE), ALIMA (Alliance for International Medical Action), and others responded to the outbreak.

According the March 2017 FAO Risk Assessment pdf icon[PDF- 1.67MB]external icon, “Animal movements, trade and changes in weather conditions are the main risk factors in RVF (re)occurring in West Africa and spreading to unaffected areas.” By early December 2016, accumulating disease data suggested that the outbreak of RVF was of modest size, and plans to explore other etiologies were formulated.

References:

WHO: Disease Outbreak News, 29 September 2016. Rift Valley Fever in Nigerexternal icon and unpublished WHO Situation Reports.

FAO: Rift Valley Fever in Niger: Risk assessment pdf icon[PDF -1.66MB]external icon, March 2017.

ALIMA: https://www.youtube.com/watch?v=9joq-Ghqghc.

2015 – Mauritania

Over the period from September to November 2015, 31 hospitalized patients who presented with severe clinical forms of RVF disease subsequently tested positive for the virus. The cases occurred in the Kiffa, Magta lahjar, Tidjikja, and Aleg regions. At least 8 people died.

References:

Boushab et al., Severe, human illness caused by RVF in Mauritania. 2015external icon. Source: Open Forum Infect. Dis. 2016, advance publication.

2013-2014 – Mauritania and Senegal

Beginning in September 2013, dorcas gazelles (gazella Dorcas) and domestic ruminants from the northern Saint Louis region of Senegal tested positive for Rift Valley Fever by RT-PCR. Epidemiologic surveillance also detected human cases in Senegal’s capital city of Dakar, and in the Linguere, Mbour and Kediougou regions. The outbreak coincided with preparations in Senegal for Eid-el-Kebir, the annual Muslim celebration. Five areas in Mauritania reported cases in camels and small ruminants from September 2013 to January 2014.

References:

RVF notifications Mauritania Senegal, 2013-2014external icon. Source: World Organization for Animal Health (OIE).

Sow et al., Widespread RVF emergence in Senegal, 2013-2014external icon.Source: Open Foreum Infect. Dis. 2016, 3-33.

2012 – Mauritania

In October 2012, the Ministry of Health in Mauritania declared an outbreak of Rift Valley Fever, starting in September. A large but unspecified number of ruminants were affected, together with more than 34 human cases, including 17 deaths, from six regions (Assaba, Brakna, Hodh Chargui, Hodh Gharbi, Tagant and Trarza). Most of the human cases had a history of contact with animals or sick animals. No virus was isolated from collected mosquitoes.

References:

RVF in Mauritania pdf icon[PDF – 2.76MB]external icon. Source: WHO Wkly Epidem. Rec. 2012, 87-438.

Sow et al., RVF outbreak Southern Mauritania, 2012. Source: Emerg. Infect. Dis. 2014, 20-296.

2009-2011 – South Africa and Namibia

Following small sporadic outbreaks of Rift Valley fever in 2008-2009, a widespread epidemic occurred in 2010 and 2011 in South Africa. More than 250 human cases occurred, including 25 deaths, and more 14,000 animal cases, with 8,000 deaths, occurring in animals. Hemorrhagic complications and hepatitis were noted in patients with severe disease. Occupational data indicated that most patients had a history of direct contact with animals through their work with RVF-infected ruminants. During May–July 2010 in Namibia, outbreaks of Rift Valley fever were reported to the National Authorities in there. The RVF viruses circulating in Namibia were identical to the South African 2010 viruses.

References:

Archer et al. Epidemiologic investigations outbreaks of RVF in humans South Africaexternal icon. Source: Emerg. Infect. Dis. 2013, 19: 1918-1925.

Métras et al. Exploratory space-time analyses of Rift Valley fever in South Africa in 2008–2011external icon. Source: PLoS Negl. Trop. Dis. 2012, 6:e1808.

Monaco et al. RVF in Namibia 2010external icon. Source: Emerg. Infect. Dis. 2013, 19: 2025-2027.

2010 – Mauritania

In October and November 2010, an outbreak of RVF was reported in the provinces of Atar and Inchiri, located in the northern part of Mauritania. Cases in animals and humans seemed to occur a short time after intense and unusual rainfalls. Severe clinical signs and high mortality was described among dromedary camel. At least 63 human cases were noted, including 13 deaths. RVFV strains were isolated from both human and Cx. antennatus mosquitoes.

References:

Faye et al., Reemergence of RVF Mauritania, 2010.external icon Source:Emerg. Infect. Dis. 2014, 20-300.

El Mamy et al., Unexpected RVF outbreak Northern Mauritaniaexternal icon. Source: Emerg. Inf. Dis. 2011, 17-1894.

2010 – South Africa

In February 2010, South Africa’s National Institute of Communicable Diseases (NICD) informed CDC of an ongoing outbreak of RVF affecting both animals and humans in seven provinces in that country. As of May 3, 2010, NICD has reported a total of 172 human cases of RVF and 15 deaths. Hemorrhagic complications and hepatitis were noted in patients with severe disease. Occupation data for 139 of the 172 indicates that 81% had direct contact with animals through their work with RVF-infected ruminants.

References:

WHO Disease Outbreak News, 30 March 2010. Rift Valley Fever in South Africaexternal icon

2006 – Kenya, Tanzania, and Somalia

In December 2006, the Kenya Ministry of Health received reports of unexplained fatalities associated with fever and generalized bleeding from Garissa District in North Eastern Province. The outbreak was confirmed by isolation of RVF virus from 10 patients. CDC deployed a 6-person team from the Viral Special Pathogens Branch to assist in outbreak response, diagnostic assays, database creation and management, technology transfer and public health messaging. The team, in collaboration with CDC’s International Emerging Infections Program (IEIP) Kenya, WHO, MSF and other partners, engaged in case finding, determination of risk factors, and a follow-up study. Like earlier outbreaks of RVF, this outbreak was also associated with recent heavy rainfalls.

References:

Anyamba et al. Prediction assessment of RVF activity in East and southern Africaexternal icon. Source Am. J. Trop. Med. Hyg. 2010, 83(suppl 2): 43-51.

Mohamed et al. Epidemiologic and clinical aspects of RVF outbreak in Tanzaniaexternal icon. Source Am. J. Trop. Med. Hyg. 2010, 83(suppl 2): 22-27.

Nguku et al. Investigation on a major outbreak of RVF Kenya 2006-2007external icon. Source Am. J. Trop. Med. Hyg. 2010, 83(suppl 2): 5-13.

2000 – Saudi Arabia and Yemen

In September 2000, the Ministry of Health of the Kingdom of Saudi Arabia, and subsequently the Ministry of Health of Yemen received reports of unexplained hemorrhagic fever in humans and associated animal deaths from the southwestern border of Saudi Arabia and Yemen. CDC confirmed the outbreak to be caused by RVF virus.

References:

Shoemaker et al. Genetic Analysis of Viruses Associated with Emergence of Rift Valley Fever in Saudi Arabia and Yemen, 2000-01. Emerg Infect Dis. 2002. Dec, 8(12).

Update: Outbreak of Rift Valley Fever—Saudi Arabia, August—November 2000 Source: MMWR 2000, 49(43);982-985.

Outbreak of Rift Valley Fever—Saudi Arabia, August—October, 2000 Source: MMWR 2000, 49(40);905-908.