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Rift Valley Fever Outbreak, Saudi Arabia, 27/5/1421 - 30/1/1422 H


On 2/6/1421 H King Fahad Central Hospital in Jazan started to receive cases of unexplained hemorrhagic fever in humans, with a clinical picture that included low grade fever, abdominal pain, body ache, vomiting, diarrhea and jaundice, with liver and renal dysfunction, often progressing to disseminated intravascular coagulation, hepatorenal syndrome and death. Different samples were sent to the referral laboratory in Riyadh and the CDC, which came back positive for RVF virus, which appearance was for the first time outside Africa. Immediately after confirmation of the result the concerning ministries started implementing preventive measures.


Case definitions were developed, both for suspected and confirmed cases, and distributed to all hospitals and primary health care centers, to detect cases. Cases were reported through a channel of active reporting system which included: primary health care centers, hospital information centers and an operation center established by the Ministry of health. The responsibilities and means of communications were distributed so that everyone involved had a clear idea of the plan of action.


This outbreak was reported during the period from 27/05/21 to 30/01/22 H in the Southwestern region of Saudi Arabia. The total number of cases were 882, out of them 747 were Saudis, 113 Yemenis, and 22 of other nationalities; 709 (80%) were males and 137 (20%) were females (male to female ratio 4:1). The distribution of cases by region showed that 413 were from Jazan, 421 from Asir, 31 from Qunfudha, and the rest from other regions in the kingdom. The mean age was 45.7 years (SD ± 20.2). The epidemic curve showed 2 peaks; in week 4 and week 10. The total numbers of deaths were 124 with a case fatality rate of 14.1%. Acute clinical symptoms included fever in 90.5%, nausea in 57.8%, and vomiting in 51%. The laboratory investigations showed that most cases had thrombocytopenia, anemia, elevated liver enzymes and creatinine, and increased bleeding time. Sixty six percent had been exposed to animals, and 97% to mosquitoes. The most common complications were hemorrhagic RVF in 49 (7.6%) of 649 patients. Encephalitis developed in 110 (17.7%) of 622. Visual complications developed in 13 (2%) out of 632 patients.


The disease is reported for the first time outside Africa. It may have spread to the area through infected imported animals or through mosquitoes transmitted by travelers or the wind. The disease started at Ardah Governorate in Jazan region then spread to Asir and Qunfuda, either by infected animals or mosquitoes. This outbreak is similar to most outbreaks whereby increased abortions among animals and increased animal deaths, especially among newborn, is the first characteristic of the disease. The clinical picture of the disease, laboratory findings, and complications are similar to other RVF outbreaks.