Of 81 reports analysed, 39 dealt with the epidemiology of HPeV meningeal infection [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43].

The reported percentage of HPeV positivity on Cerebrospinal Fluid (CSF) in children with meningeal involvement varied in American patients from 0.4 to 8.9%, with epidemic waves being occasionally reported [5,6,7,8,9,10]. HPeV type 3 was the most frequently detected single viral type [9].

As for Europe, many European Countries have been involved in epidemiological studies and highlighted the HPeV meningitis outbreak as well [11, 12]. The reported incidence in European patients varied as well from 0,04 to 10% [13,14,15,16,17,18,19,20,21,22,23,24,25,26].

Incidence of HPeV meningitis in the Asian continent has been studied mainly in Japan and Korea [27,28,29,30,31,32,33,34]. A multicentre study, conducted in Japan identified 240 infants with HPeV type 3 infection, of which 14.2% diagnosed with acute CNS infection [28]. Among 216 patients aged less than 4 months and hospitalised for fever, 110 were found to have a viral infection on serum or CSF, caused by HPeV in 60 cases [30]. In Korea the reported incidence varied from 8,6 to 37% [31,32,33,34].

As well as for other Continents, in Oceania incidence was varying from 5,4% to 25,8%, depending on the case series and period time considered [38,39,40].

Incidence of HPeV meningitis in the African continent seemed to be low. In Sudan, between December and August 2010 no patient was found positive for HPeV on CSF, out of 503 children aged 0 to 15 years presenting with fever, seizures, and a suspicion of neuroinfection [42]. Nine years later in the Comoros archipelago, HPeV RT-PCR were performed on 122 CSFs, of which 77 were collected from children, and only a 30-days-aged infant presented with a CSF HPeV infection (0,8%) [43]. The Countries involved in the studies are represented on the Map in Fig. 2.

Countries involved in the studies are shown in blue on the World map. They were Argentina, Australia, Canada, Comoros, France, Germany, Greece, Ireland, Israel, Italy, Japan, Netherlands, New Zealand, Poland, Portugal, Qatar, Singapore, South Korea, Spain, Sudan, Taiwan, Turkey, United Kingdom., USA.

Some reports described the seasonality of the HPeV infection, with most of the cases presenting in the warmer months of the year [8,9,10,11,12, 18, 19, 27, 34, 43]. Whereas other studies didn’t find evidence of seasonality connected to HPeV meningitis [13,14,15,16,17,18,19,20,21,22,23,24,25,26].

Regarding the molecular epidemiology of HPeV infection, HPeV type 3 was the predominant genotype, as reported by most studies analysed by this review [8, 9, 11, 17, 19, 21, 26, 27, 40]. Chamings A et al. described two cases of HPeV meningitis caused by the recombinant HPeV type 5 [41].

Of 81 reports analysed, 47 dealt with the clinical presentation of HPeV meningeal infection [1, 8,9,10,11,12, 14, 17, 21, 23, 25,26,27,28, 32, 33, 41, 44,45,46,47,48,49,50,