Evaluation of enterovirus serological tests IgM-EIA and complement fixation in patients with meningitis, confirmed by detection of enteroviral RNA by RT-PCR in cerebrospinal fluid

Seasonal Testing, Results, and Effect of the Pandemic on Coxsackievirus Serum Studies

Coxsackieviruses (CVs) are common causes of infections and can be life-threatening. Unfortunately, rigorous studies guiding the clinician in interpreting CV serum antibody titer testing is lacking. To explore the epidemiology of circulating CVs and the serological test utility in aiding diagnosis of CV infections in our community, we obtained results of CV immunologic diagnostic tests between 2018 and 2022 from a regional healthcare database. For CV type A, rare individuals had positive CF (complement fixation) tests whereas all 16 individuals with IFA testing showed at least one positive serotype. For CV type B CF testing, 52.2% of 222 patients had at least one serotype positive, with B5 being most common and also the most common with higher titers (14.8% with ≥1:32). We found a significant reduction in seropositivity rate during the pandemic in 2020 compared to 2018, which continued through 2022 (OR: 0.2, 95% CI: 0.08-0.49, p-value < 0.001). During the pandemic, the seasonal pattern of positive tests varied from the pre-pandemic pattern. Testing for CVs was increased after the first year of the pandemic. Overall, the variability by month and seasonal change in our data support that CF testing can be used to identify recent CVB infection.

Enteroviruses and Parechoviruses

Infections with enteroviruses and human parechoviruses are highly prevalent, particularly in neonates, where they may cause substantial morbidity and mortality. Individuals with B-cell-related immunodeficiencies are at risk for severe enteroviral infections, usually a chronic and fatal meningoencephalitis. In transplant recipients and patients with malignancy, enterovirus infections typically involve the respiratory tract, but cases of severe, disseminated infection have been described. The mainstay of diagnosis for enterovirus and human parechovirus infections involves the use of molecular diagnostic techniques. However, routine nucleic acid-detection methods for enteroviruses will not detect human parechoviruses. Laboratory diagnosis of these viral infections is important in determining a patient's prognosis and guiding clinical management.

Frequency of enterovirus detection in blood samples of neonates admitted to hospital with sepsis-like illness in Kuwait

This study investigated the role of enteroviruses in sepsis-like illness among neonates in Kuwait. Serum samples from 139 consecutive neonates presenting with sepsis-like illness during a three and a half-year-period whose blood cultures were negative for bacterial pathogens were tested. Enterovirus RNA was detected by single-step reverse-transcription PCR (RT-PCR). Specific genotypes were identified by direct DNA sequencing of enteroviral genome. Serotype-specific antibodies in serum samples from some selected patients were detected by virus neutralization test using coxsackievirus B types (CBVs). All 139 neonates presented with sepsis-like illness and blood samples were uniformly negative for aerobic/anaerobic bacterial cultures. Fifty-six (40%) neonates had further complications of sepsis including carditis (n = 34) and multi-organ involvement (n = 22). Enterovirus RNA was detected by RT-PCR in 34 of 139 (24%) serum samples which is among the highest frequency reported so far in non-epidemic settings. Genotyping identified CBVs as most common enteroviruses, causing 19 of 34 (56%) enteroviral sepsis episodes in neonates. Of 34 carditis cases, 18 were positive for CBVs by serotyping including all 10 enterovirus RNA-positive samples. Only one fatality was observed due to liver failure in a neonate with hepatitis. Our data showed that enteroviruses are responsible for 24% of neonatal sepsis cases due to non-bacterial causes in Kuwait. The data indicate that enteroviruses should be considered in the differential diagnosis of sepsis-like illness among neonates, particularly those with negative blood cultures for bacterial pathogens.

Enterovirus infections in neonates

Enteroviruses, which include echoviruses, coxsackie A and B viruses, polioviruses and the 'numbered' enteroviruses, are among the most common viruses causing disease in humans. A large proportion of enteroviral infections occur in neonates and infants. There is a wide spectrum of clinical manifestations that can be caused by enterovirus infection with varying degrees of severity. In the neonatal age group, enteroviral infections are associated with significant morbidity and mortality, particularly when infection occurs antenatally. This review provides a detailed overview of the epidemiology and clinical features of enterovirus infections in the neonatal period. In addition, laboratory features and diagnostic investigations are discussed. A review of the currently available data for prophylactic and therapeutic interventions, including antiviral therapy, is also presented.

Presentation, diagnosis, and management of enterovirus infections in neonates

The nonpoliovirus enteroviruses commonly infect newborns, with consequences ranging from asymptomatic infection and benign illness, to severe, life-threatening disease. Frequently occurring symptoms include fever, irritability, lethargy, anorexia, and rash. Although most illnesses are mild, severe disease develops in a subset of newborns infected in the first 2 weeks of life. Severe disease may consist of sepsis, meningoencephalitis, myocarditis, pneumonia, hepatitis, and/or coagulopathy. Substantial mortality rates have been reported, and long-term sequelae may occur among survivors. Risk factors and clinical features associated with severe disease include absence of neutralizing antibody to the infecting serotype, maternal illness prior to or at delivery, prematurity, illness onset within the first few days of life, multiorgan disease, severe hepatitis, positive serum viral culture, and specific infecting serotype (e.g. group B coxsackieviruses and echovirus 11). Whereas the mainstay of diagnosis has traditionally been viral isolation in tissue culture, the polymerase chain reaction has been demonstrated to be more sensitive than culture, highly specific, and rapid. Immunoglobulin has been used as a therapeutic agent for neonates with enterovirus disease; however, clinical efficacy has not been proven. Specific antiviral therapy for enteroviruses is in development. Pleconaril is an investigational agent that inhibits viral attachment to host cell receptors and uncoating of viral nucleic acid. It has broad and potent anti-enterovirus activity, excellent oral bioavailability, and is well tolerated. Some clinical trials have demonstrated benefit in children and adults with enterovirus meningitis, and in adults with upper respiratory tract infections caused by picornaviruses (rhinoviruses or enteroviruses). Data summarizing compassionate use for severe enterovirus diseases (including neonatal sepsis) also suggest possible benefit. Limited pharmacokinetic data are available in infants and neonates. A multicenter, placebo-controlled, randomized trial of pleconaril in neonates with severe hepatitis, coagulopathy, and/or myocarditis is currently being conducted.

Diagnosis of enterovirus infection by genus-specific PCR and enzyme-linked immunosorbent assays

PCR for the diagnosis of enterovirus infections is resource intensive but is increasingly used due to wide availability. Enzyme-linked immunosorbent assays (ELISAs) that detect heterotypical antibodies against enterovirus immunoglobulin M (IgM), IgA, and IgG were compared with reverse transcription-PCR by using primers specific to the 5' untranslated regions of 60 enterovirus species. The ELISAs were less sensitive than the PCR, and only the ELISA for IgM was highly specific. When retrospective diagnosis is important or when specimens are unsuitable for PCR, the ELISA has a limited role if PCR is not available.