Viral etiologies are the leading cause of CNS infections, including meningitis and encephalitis, worldwide (
8). A wide range of viral agents, including HSV, EBV, CMV, VZV, HHV6, and EV, have been reported. Additionally, COVID-19 is a multi-system disease that can affect not only the respiratory and cardiovascular systems but also the digestive and nervous systems (
22). Despite numerous connections between different risk factors and CNS disorders, viral infections remain a major focus of discussion (
23). Since the symptoms of these CNS diseases are non-specific, molecular analysis, such as real-time PCR, is essential to identify the causative agents. This study investigated the presence of SARS-CoV-2, Herpesviridae (HSV, CMV, VZV, and EBV), Picornaviridae (EV), and Polyomaviridae (JCV) in the CSF of patients presenting with signs of HSV meningitis and encephalitis during the COVID-19 pandemic.
In 166 CSF samples from patients with neurological symptoms tested by PCR, 22 (13.3%) were positive for one of the viruses. Among these, we detected 11, 6, 3, 2, and 1 cases of HSV-1, SARS-CoV-2, CMV, VZV, and JC, respectively, but no EBV cases were identified. This study identified 11 patients with HSV; however, detailed clinical information was available for only 8 patients, all of whom had HSV encephalitis. All patients diagnosed with HSV were treated with intravenous acyclovir and discharged without complications.
A 2017 study from Turkey reported the prevalence of HSV-1 and HSV-2 as 1.80% (24/1333) and 0.08% (1/1333), respectively (
24). Another research study identified 21 samples with HSV-1 and 74 samples with HSV-2. Encephalitis was observed in most HSV-1 cases, while several HSV-2 patients exhibited symptoms of meningitis. In our previous study in 2011, we identified viruses in 46% (30/65) of patients admitted to the hospital with aseptic meningitis. Among these, 13 (43.3%) and 11 (36.7%) cases were caused by non-polio human enterovirus and mumps virus, respectively. HSV, VZV, HCMV, and HHV-6 accounted for the remaining 6 (20%) cases (
25).
Two patients in our study tested positive for VZV despite the absence of any skin lesions. Other reports have documented cases of VZV CNS infection detected by PCR without the usual skin manifestations. EBV meningitis was not detected in any of the patients in the present study; however, HCMV meningitis was identified in three patients who did not have a meningitis diagnosis. Aseptic meningitis caused by HCMV and EBV is rare. According to a 2017 investigation in Turkey, a small percentage of patients were infected with other Herpesviruses, including VZV, HCMV, and HHV-6 (
26). In Ukraine, among 107 patients, 12.1% had HSV-1 or HSV-2, 1.8% had VZV, 13.5% had CMV, 20.5% had EBV, 5.5% had HHV-6, 12.1% had HHV-7, and 35.5% had multiple HSV types (
27).
Our study identified one patient with JCV detected in the CSF, marking the first report of JCV detection in CSF from Iran, to the best of our knowledge. JCV is a prevalent human polyomavirus that can infect individuals without causing disease. Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease that occurs when JCV is reactivated, leading to the destruction of oligodendrocytes and astrocytes (
28). However, JCV meningitis and encephalitis have been reported in only a few cases involving immunocompetent patients (
28,
29). Our patient was a 4-month-old boy without CSF pleocytosis who was discharged with a diagnosis of MIS-C and sepsis (
30).
We reported six cases of SARS-CoV-2 infection with CSF involvement confirmed by viral RNA detection. Of these, two were a 2-day-old boy and a 2-month-old girl, both suspected of having meningitis. The CSF analysis results for these patients were normal, and they were treated for sepsis. Another case involved a 16-year-old male patient undergoing treatment for hepatoblastoma, who unfortunately died nearly two weeks after hospital admission due to HCC-associated liver failure. A 79-year-old woman with hyperlipidemia was another case; despite treatment, her condition deteriorated, and she remained on supportive care until her death 2.5 months after admission. SARS-CoV-2 RNA was retrospectively detected in the CSF samples of these patients. Although they were diagnosed with other medical conditions, COVID-19 encephalitis could not be definitively ruled out.
Unfortunately, no documentation was available for the other patients. Positive nasopharyngeal tests were not recorded for patients whose clinical data were available. Several hypotheses have been proposed to explain this neural involvement. One theory suggests that the CNS is accessed through hematogenous diffusion via a leaky blood-brain barrier or retrograde neural pathways, such as through the cribriform plate and olfactory bulb. The ability of the SARS-CoV-2 spike protein to bind to ACE-2 (angiotensin-converting enzyme 2) receptors on capillary endothelium may facilitate viral entry into the CNS.
Previous studies have indicated no correlation between a positive nasal swab sample and the presence of the virus in the CSF of neurologically symptomatic patients. To date, only a small number of patients with neurological symptoms and CSF analysis have tested positive for SARS-CoV-2 by RT-PCR in CSF. These findings suggest that viral infections were not a significant contributor to the clinical presentation. Further research is needed to clarify the role of SARS-CoV-2 in the development of meningoencephalitis, particularly in suspected CSF infections. The results section summarizes the clinical and paraclinical findings of these patients. Frequent CSF findings included occasional hyperproteinorrachia and mild lymphocytic pleocytosis.
In another study, 118 ICU patients with acute respiratory distress syndrome caused by SARS-CoV-2 infection exhibited delirium and/or abnormal neurological evaluations. An Argentinian study identified two cases of CNS involvement with positive real-time RT-PCR results in CSF. In another 2021 study, only one of 21 CSF samples tested positive for SARS-CoV-2 by RT-PCR.
A systematic review of SARS-CoV-2 patients with confirmed viral presence in CSF identified 23 cases. Seven cases (30.4%) were reported in Iran, four cases (17.4%) in Brazil, and two cases (8.7%) each in the UAE and USA. The apparent higher prevalence of SARS-CoV-2 in CSF than reported in the literature may reflect the lack of SARS-CoV-2 CSF PCR testing or non-lumbar puncture diagnostic tools. A false positive result is highly unlikely, as the PCR test for SARS-CoV-2 has near-perfect specificity.
Various factors may account for the low viral detection rate among patients suspected of CNS infections. Firstly, CSF analysis is indicated in patients presenting with a wide range of clinical manifestations caused by infectious and inflammatory diseases. A broad spectrum of infectious and inflammatory conditions may mimic CNS viral infection [Whitley et al., 1989; Adler-Shohet et al., 2003]. Additionally, the test was designed to detect nucleic acid from a limited range of viruses and other microbes potentially associated with encephalitis or meningitis. Another factor influencing the detection of viral nucleic acid is the time elapsed between the onset of neurological symptoms and CSF sampling.
The limitations of our study, conducted during the COVID-19 pandemic, significantly hindered our ability to collect a larger sample size. Furthermore, our single-center approach restricted access to CSF samples, potentially affecting the generalizability of our findings. Despite these limitations, we believe our results provide valuable insights into the viral causes of CNS infections during this period.
5.1. Conclusions
This study, conducted at Nemazi Teaching Hospital, analyzed CSF samples from patients suspected of having meningitis to identify viral pathogens. The results revealed that Herpes simplex virus-1 (HSV-1) was the most prevalent virus detected, followed by SARS-CoV-2. These findings highlight the importance of conducting viral tests in suspected meningitis cases, as accurate identification of causative agents is essential for effective diagnosis and treatment. Gaining a better understanding of the viral landscape can significantly enhance patient management and improve outcomes in meningitis cases.