Epidemiological characterization of viral etiological agents of the central nervous system infections among hospitalized patients in Egypt between 2016 and 2019

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Viral infection of the CNS is one of the most important causes of neurologic illness. The circulatory patterns of viruses that cause CNS infections, i.e., meningitis, encephalitis, and others, are country dependent, and there is only limited epidemiologic data on the prevalence of viral CNS infections in Egypt. We used multiplex RT-qPCR to screen CSF samples for 12 viral pathogens, after confirming that the samples were negative for bacterial CNS infection. The multiplex PCR methodology represents a milestone in the rapid detection of RNA and DNA viruses in CSF, easing the diagnosis of infection and the prescription of antivirals both locally and worldwide.

Of the 1735 patients who had neurologic symptoms, 330 were confirmed to be positive for a viral pathogen. The mortality associated with viral infection of the CNS is higher than that associated with viral infections of other systems [20]. Similar to previous global reports, the case fatality rate among the virus-positive cases in our study group was 13%.

In consistent with previous studies{Kohil, 2021 #380}, viral infections were most common in young children (< 1–10 years) with 43.9% but is seen across all age groups and this could be due to a combination of immunological factors, as well as, close contact with other children, and poor hygiene habits.

The predominance of male patients with viral CNS infection in our study of cases in Egypt was consistent with the findings of other studies in different countries [20,21,22]. HEV was the most predominant virus in our study, being present in 37.3% of virus-positive samples, which is similar to the results reported by others [23, 24]. In our study, the frequency of infection with HEV was highest in the summer months and in patients between 4 and 17 years of age, which is also consistent with other reports [25].

Akkaya et al. [24] also found HEV to be the leading causative agent of CNS infection and to have the highest prevalence in children and in summer, although they reported AdV to be the second most predominant virus, whereas in our study AdV was detected in only five of the 330 virus-positive cases (1.5%). In our study, HSV-1, EBV, and HSV-2 followed HEV in prevalence overall, although HSV-2 and VZV were reported to be prevalent in some regions.

Kupila et al. [5] also reported HEV to be the leading cause of viral meningitis, followed by HSV-2, whereas we found HSV-1 to be the second most predominant virus, and also found HSV-1 to be one of the most common viral causes of meningitis.

VZV was reported by Kupila et al. to be the third leading cause of viral CNS infection [5], but in our study it ranked seventh, being found in only 12 of the 330 virus-positive cases (3.6%), with EBV being the third most prevalent virus. Our findings are consistent with those of [26], who reported EBV to be one of the main causes of single-virus and mixed-virus encephalitis and aseptic meningitis,

In our study, HPeV was not detected in any sample, which is in marked contrast to previous studies [27,28,29] that found HPeV to be the second most predominant virus causing CNS infection and an important cause of sepsis-like illness in infants. Our results may be partly explained by the finding of Harvala et al. [30] that HPeV is less frequent in sepsis or meningitis in neonates than in older patients but is associated with gastroenteritis.

Although MuV was the most common cause of viral meningitis a few decades ago, we detected it in only one sample in our study. This may be a consequence of the introduction of measles–mumps–rubella vaccine in Egypt in the 1990s.

The etiologic diagnosis was achieved in 43% of the patients with meningitis and in 17% of those with encephalitis by RT-qPCR, which is an important method for the rapid detection of RNA and DNA viruses in CSF. RT-PCR has demonstrated a specificity range of 94%–100%, and these multiplex RT-PCR assays can supplement other diagnostic tests.

In our study, 30 patients had mixed infections involving CMV, HHV-7, MuV, B19V, and/or HEV, EBV, or VZV. Dyachenko et al. [31] also reported mixed infections involving more than one virus.

This study has some limitations, including the exclusion of the West Nile virus, Japanese encephalitis virus, Tick-borne encephalitis virus, and Zika virus from our screening due to a lack of diagnostic tools. Data obtained from this study will contribute to improving the clinical management of viral infections of the CNS in Egypt.

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Categorized as Virology

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