Tracking Rift Valley fever: From Mali to Europe and other countries, 2016

Abstract

On 16 September 2016, the World Health Organization confirmed a Rift Valley fever (RVF) outbreak in Niger. Epidemiological surveillance was reinforced among the French Armed Forces deployed in Niger and bordering countries: Chad, Mali and Burkina Faso. On 26 October, a probable case of RVF was reported in a service member sampled in Mali 3 weeks earlier. At the time the result was reported, the patient was on vacation on Martinique. An epidemiological investigation was conducted to confirm this case and identify other cases. Finally, the case was not confirmed, but three suspected cases of RVF were confirmed using serological and molecular testing. RVF viral RNA was detectable in whole blood for 57 and 67 days after onset of symptoms for two cases, although it was absent from plasma and serum. At the time of diagnosis, these cases had already returned from Mali to Europe. The infectivity of other arboviruses in whole blood has already been highlighted. That RVF virus has been detected in whole blood that long after the onset of symptoms (67 days) raises the question of its potential prolonged infectivity. Because of exposure to tropical infectious diseases during deployment, military populations could import emerging pathogens to Europe.

The challenging management of Rift Valley Fever in humans: literature review of the clinical disease and algorithm proposal

“…Arboviruses pose a major threat of introduction to several continents, including Europe and North America, with the possibility of cocirculation [7]. The widespread presence of competent vectors, the high viral load in infected animals, trade and global travel, all increase the likelihood of RVFV exportation and establishment outside endemic regions [8][9][10]. Cases have already been imported to Europe and Asia [9,11,12] and concerns have raised about its potential to extend to other parts of Asia, Europe [13] and United States [14,15].…”

“…Autopsy studies and pathogenesis characterization in mouse model found evidence of liver necrosis with RVF viral antigens identified within hepatocytes and Küpffer cells, arguing for a direct virus-induced cellular necrosis [19,37,44,57,59,60]. A RVF case with a co-existing condition of cirrhosis after hepatitis B infection died as a result of gastrointestinal bleeding and hepatic encephalitis in Mayotte [28], and 4/31 (13%) severe cases described during the epidemic in Mauritania in 2015 had chronic hepatitis B [61], suggesting that patients with chronic hepatic ACUTE OR DELAYED ENCEPHALITIS day VISION DISORDERS day [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] disorders-mainly hepatitis B chronic infection-could be at higher risk of unfavorable outcome.…”

“…Specimens must be labelled, packaged in accordance with the guidelines for the transport of dangerous biological goods (triple packaging), stored at 4 °C and addressed to a reference center. If necessary, whole-blood specimens can be dried on blotting paper, stored 30-60 days and transported without refrigeration for retrospective diagnosis confirmation [9].…”

“…Viral isolation is also an assay for laboratory confirmation of RVFV infection but this assay needs to be done on BSL3 and is less sensitive than detection of viral RNA by RT-PCR. Interestingly, RT-PCR for RVFV was reported positive for a prolonged period in urines, semen [74] and whole blood [9]. The RVFV RNA load in blood usually decreases between days 1 to 4 and may be detectable until day 8 after the onset of symptoms [9].…”

“…Interestingly, RT-PCR for RVFV was reported positive for a prolonged period in urines, semen [74] and whole blood [9]. The RVFV RNA load in blood usually decreases between days 1 to 4 and may be detectable until day 8 after the onset of symptoms [9]. Prolonged and intense viremias were reported during acute encephalitis and hemorrhagic fever.…”