Research Article: The Risk of Nosocomial Transmission of Rift Valley Fever

Date Published: December 22, 2015

Publisher: Public Library of Science

Author(s): Nasser A. Al-Hamdan, Anil A. Panackal, Tami H. Al Bassam, Abdullah Alrabea, Mohammed Al Hazmi, Yagoub Al Mazroa, Mohammed Al Jefri, Ali S. Khan, Thomas G. Ksiazek, Brian Bird.

Abstract: In 2000, we investigated the Rift Valley fever (RVF) outbreak on the Arabian Peninsula—the first outside Africa—and the risk of nosocomial transmission. In a cross-sectional design, during the peak of the epidemic at its epicenter, we found four (0.6%) of 703 healthcare workers (HCWs) IgM seropositive but all with only community-associated exposures. Standard precautions are sufficient for HCWs exposed to known RVF patients, in contrast to other viral hemorrhagic fevers (VHF) such as Ebola virus disease (EVD) in which the route of transmission differs. Suspected VHF in which the etiology is uncertain should be initially managed with the most cautious infection control measures.

Partial Text: Rift Valley fever (RVF) is a zoonotic disease caused by an RNA virus in the genus Phlebovirus, family Bunyaviridae. RVF virus is transmitted to humans primarily by mosquito bites and by direct contact with infected animal body fluids [1]. First described in Kenya in 1910, the disease has been recognized in many African countries with a severity ranging from localized, well controlled clusters to major epizootics and associated epidemics [2]. In August 2000, the first confirmed occurrence of RVF outside the African continent was described on the Arabian Peninsula along the Red Sea coast in southwestern Saudi Arabia and Yemen. This outbreak illustrated that the RVF virus can adapt to different ecological conditions and cause infection in humans and domestic ungulates, provided suitable mosquito vectors and animal reservoirs are present.

The study was conducted under the auspices of the Ministry of Health and Field Epidemiology Training Program, Kingdom of Saudi Arabia and with the assistance of CDC as an outbreak response related activity. In addition, we obtained visiting country equivalent institutional review board (IRB) approval for a clinical trial of ribavirin for RVF as an adjunct to this study–all part of the overall RVF outbreak response. The risk to HCWs for acquiring RVF in the hospital setting was assessed at four hospitals in the Jazan province–where the outbreak began—during October 22–26, 2000, which corresponded to the end of the peak of the outbreak (three months after it began in August 2000): King Fahad Central Hospital (KFCH), Samtah General Hospital (SGH), Al Ardah Hospital (AH), and Beash Hospital (BH). KFCH was the regional referral hospital, whereas the others were located in the hyperendemic areas. The study was begun approximately three months into the RVF outbreak in Jazan, when on average 50 to 75 new cases were being reported on a weekly basis. From August to October, a total of approximately 400 RVF patients were hospitalized at these four facilities. We were not able to obtain information on how many required intensive care unit admission or had severe manifestations, but these likely represented the minority, given what is known about the natural history of most RVF infections.

A total of 703 HCWs participated in this study. Three hundred and forty-six (49%) were males and the mean age was 33 years (range: 20–64 years; standard deviation: ± 9 years). The most common nationalities included Indians (37%), Saudi Arabians (26%), and Filipinos (12.5%). Two hundred sixty-six (37.8%) were from KFCH and 240 (34.1%) were from SGH, where precautionary measures, such as the use of gloves, gowns, and face masks, were widely implemented. However, of the remaining HCWs, one hundred eleven (15.8%) were from AH and 86 (12.2%) were from BH, where the use of protective measures was less common. By occupation, 80 (11%) were physicians, 312 (44.6%) were nurses, 43(6.2%) were laboratory technicians, 115 (16.5%) were cleaners, and 153 (21.7%) had other jobs.

Serological evidence suggests that only four (0.6%) of the 703 HCWs were infected by RVF virus. Our data suggest that these infections were probably the result of community exposure rather than nosocomial acquisition. Nosocomial transmission, if it occurs, appears to be very rare in the context of at least rudimentary standard precautions. These data suggest that the risk for hospital-acquired RVF in HCWs is very low and that the use of standard precautions alone afford sufficient protection to HCWs who deal with known RVF patients.



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