Usutu is an arbovirus from the same family as the Zika and West Nile viruses. Like its cousins, it is transmitted by mosquitoes. While we know that it is responsible for high mortality in birds, principally passerines, knowledge on human pathology remains limited.
Only 26 cases of human infection by Usutu have been reported in Europe, a figure which is most certainly underestimated according to Yannick Simonin, lecturer-researcher specialized in the virus, given the non-existence of commercial screening tests and the general ignorance of the associated symptoms.
Animal studies show very strong neurological tropism of Usutu. Very recently, Simonin and his team from Unit 1058 “Pathogenesis and control of chronic infections” (Inserm/Université Montpellier/Montpellier University Hospital/ EFS) published in Emerging Infectious Diseases results showing its presence in the cerebrospinal fluid of a patient from Montpellier University Hospital in 2016, confirming this neurotropism. The clinical symptoms of the patient, which included temporary facial paralysis, had not until that point been linked to any specific disease. Additional investigations are necessary if we are to improve our understanding of the clinical picture associated with this emerging virus.
The research activities developed by JRU 1058 include determining the virulence, notably neuronal, of the various Usutu strains circulating in France in order to compare them in the laboratory and evaluate their pathogenicity. The Unit is also studying the transmission mechanisms of the virus in order to better elucidate the associated risks.
The Astre unit of CIRAD partner of Unit 1058 for this study, is also participating in vector mapping the Usutu virus.