Active and passive surveillance for bat lyssaviruses in Italy revealed serological evidence for their circulation in three bat species

Abstract

The wide geographical distribution and genetic diversity of bat-associated lyssaviruses (LYSVs) across Europe suggest that similar viruses may also be harboured in Italian insectivorous bats. Indeed, bats were first included within the passive national surveillance programme for rabies in wildlife in the 1980s, while active surveillance has been performed since 2008. The active surveillance strategies implemented allowed us to detect neutralizing antibodies directed towards European bat 1 lyssavirus in six out of the nine maternity colonies object of the study across the whole country. Seropositive bats were Myotis myotis, M. blythii and Tadarida teniotis. On the contrary, the virus was neither detected through passive nor active surveillance, suggesting that fatal neurological infection is rare also in seropositive colonies. Although the number of tested samples has steadily increased in recent years, submission turned out to be rather sporadic and did not include carcasses from bat species that account for the majority of LYSVs cases in Europe, such as Eptesicus serotinus, M. daubentonii, M. dasycneme and M. nattereri. A closer collaboration with bat handlers is therefore mandatory to improve passive surveillance and decrypt the significance of serological data obtained up to now.

Comments to “Detection and phylogenetic characterization of astroviruses in insectivorous bats from Central‐Southern Italy”

“…Thus, while eventual positive results would confirm the presence of circulating virus, the absence of evidence is not evidence of absence, even if larger numbers of bat saliva samples had been collected and tested. Therefore, enhanced passive surveillance targeting dead, sick or impaired animals displaying neurologic disease is recognized as the most suitable approach for bat rabies surveillance to gain knowledge on the possible circulation of lyssaviruses in indigenous bat populations (Cliquet et al, 2010;Leopardi et al, 2018;Wise et al, 2017).…”

“…While rabies virus (RABV), the prototype of lyssaviruses, circulates in insectivorous and vampire bats in the Americas only, European bats act as reservoirs for at least five distinct lyssaviruses, which have been recognized as autonomous virus species within the genus lyssavirus (Walker et al, 2018). Despite evidence for asymptomatic circulation in different bat species (Amengual, Bourhy, López-Roíg, & Serra-Cobo, 2007;Leopardi et al, 2018;Schatz, Ohlendorf, et al, 2014;Serra-Cobo, Amengual, Carlos Abellán, & Bourhy, 2002), each of these five lyssaviruses is associated with mortality in specific bat hosts (Banyard, Evans, Luo, & Fooks, 2014;Nokireki, Tammiranta, Kokkonen, Kantala, & Gadd, 2018). These include the following:…”

“…Although the risk of the general population to contract bat-associated lyssavirus infections is generally low, bat biologists or voluntary bat handlers are particularly at risk (Fooks, Brookes, Johnson, McElhinney, & Hutson, 2003;Racey, Hutson, & Lina, 2013). Unfortunately, such a risk is often largely underestimated in the community of bat biologists mainly due to the absence of valuable data collected from systematic and consistent passive surveillance in Italy (Figure 1) (Leopardi et al, 2018),…”

Increased detection of rabies virus in bats in Ceará State (Northeast Brazil) after implementation of a passive surveillance programme

“…Although non‐haematophagous bats are often diagnosed with rabies, mostly with virus variants characteristics of these species, to date, there have been no notified cases in humans caused by these bat species (Brasil, ). Rabies in dogs and cats is usually a priority for control measures, but in several high‐income countries such as the United States and Australia, and also in some European countries, rabies in non‐haematophagous bats likely has been a problem for a long time, but had not been adequately recognized until recently (Bonwitt, Oltean, Lang, Kelly, & Goldoft, ; Leopardi et al, ).…”

Combining host genetic structure and serology to investigate rabies-related lyssaviruses in the greater mouse-eared bat (Myotis myotis)

“…However, the discordance between the genetic structure of E. serotinus and EBLV-1 isolates in France suggests that other species might be involved in the spread of the virus (Troupin et al, 2017). This hypothesis is further supported by serological studies showing exposure of several other bat species, including the grater mouse-eared bat (Myotis myotis ) in Spain, France, Germany, Croatia and Italy (Leopardi et al, 2018;Picard-Meyer et al, 2011;Schatz et al, 2014;Serra-Cobo et al, 2013;Šimić et al, 2018). Although this bat species seems to mostly move locally between summer and winter roosts, longer transboundary migrations have also been recorded (Hutterer et al, 2005), which might contribute to virus dispersal.…”