Enterovirus D68 and other enterovirus serotypes identified in South African patients with severe acute respiratory illness, 2009-2011

Seroprevalence of Enterovirus D68 Infection among Humans: A Systematic Review and Meta-Analysis

INTRODUCTION

Human enterovirus D68 (EV-D68), which belongs to enteroviruses of the small RNA family, is a type of enterovirus that can cause acute respiratory tract infection and central nervous system diseases. This study systematically analysed and summarized EV-D68 antibody studies in databases and identified the seropositivity rates of different regions, ages, and sexes.

METHODS

Meta-analysis was performed using STATA 16.0 software. I2 and Q tests were used to analyse the heterogeneity of the included studies. Meta-regression analysis was performed for different groups, and Egger's linear regression analysis was used to evaluate publication bias.

RESULTS

The results of multiple studies indicated that the serological prevalence range of EV-D68 antibody was 17.78-96.69%. The results of the meta-analysis showed that the seropositivity rate of EV-D68 antibody was 76% (95% confidence interval [CI]: 67-84%), among which that of the Chinese population was 74% (95% CI: 61-86%) and that of other countries was 79% (95% CI: 65-91%). At the same time, a subgroup analysis was conducted. The seroprevalence of EV-D68 antibody was related to age but not sex or region.

CONCLUSION

The seropositivity rate was lower in the below 5-year age group; however, it gradually increased with age. The results of this study showed that EV-D68 infection was widespread in the population, and the current clinical infection situation could not reflect the actual epidemic situation of the virus, among which children under 5 years old were vulnerable to infection, which should be given greater attention for epidemic prevention and control.

Description of non-polio enteroviruses identified in two national surveillance programmes in South Africa

Background

Human enteroviruses (EV) consist of 106 serotypes and four species: EV-A, EV-B, EV-C and EV-D. Enteroviruses cause clinical symptoms varying from severe to mild. Knowledge of EV burden in South Africa is limited, and as non-polio EV are important causes of acute flaccid paralysis (AFP) and meningitis, information on the circulating serotypes is vital.

Methods

Between 2010 and 2012, a total of 832 stool and viral isolate specimens were obtained from two national surveillance programmes at the National Institute for Communicable Diseases: the Rotavirus Sentinel Surveillance Programme (RSSP) and the AFP surveillance programme. Real-time polymerase chain reaction and Sanger sequencing were performed to detect and serotype EV.

Results

Non-polio EV were detected in 446 specimens, of which 308 were sequenced. Stool specimens yielded a greater variety of serotypes than viral cultures. EV-B viruses were predominant (58.44%), whilst EV-C viruses were detected in 31% of the specimens tested. South African prevalence for these viruses was higher than other countries, such as France with less than 2%, and Spain and the United States with less than 10%. The most common serotype detected was Enterovirus 99 (EV-C, 8.63%), which has not been reported in other regions.

Conclusion

Direct sequencing from stool specimens yields a broader, more comprehensive description of EV infections compared to sequencing from viral cultures. Disease-associated serotypes were detected, but only in small numbers. This study provides a baseline for EV strain circulation; however, surveillance needs to be expanded to improve EV knowledge in South Africa.

Molecular epidemiology of Enteroviruses and Rhinoviruses in patients with acute respiratory infections in Yaounde, Cameroon

BACKGROUND

Acute respiratory infections (ARI) are associated with a huge morbidity and mortality worldwide. Rhinoviruses (RVs) and Enteroviruses (EVs) are recognized as leading causes of ARI.

OBJECTIVES

The present study describes the molecular epidemiology of RVs and EVs in Cameroon over a 3-year surveillance period.

METHODS

From September 2011 to October 2014, nasopharyngeal swabs were collected from patients with influenza-like illness (ILI) and severe acute respiratory infections (SARI). Two sub-genomic regions of the EVs and RVs were targeted for molecular characterization. These included the most conserved 5'-untranslated region (5'UTR) and the viral protein 4/viral protein 2 transition region (VP4/VP2).

RESULTS

A total of 974 samples were collected. Children ≤5 years accounted for 85.7% (835/974) of all participants. Among them, 160 (16.4%) were positive for RVs and/or EVs. RVs and/or EVs were significantly more identified in ILI compared to SARI patients (P = .015). Both viruses co-circulated all year long with a marked increase of occurrence during rainy and cold season. All RV species were found to circulate in Cameroon, with 6, 10 and 6 virus types belonging to the RV-A, RV-B and RV-C, respectively. EV species identified comprised EV-A (1 Coxsackie virus A5), EV-B (1 Coxsackie virus A9 and 2 Coxsackie virus B1) and EV-C (1 EV-C117).

CONCLUSIONS

This study indicates a strong year-round occurrence of EV and RV associated respiratory infections in Cameroon. Molecular characterization identified a wide variety of RVs and EVs in patients with ARI in Cameroon.

Epidemiologic and Molecular Study of EVs in Hospitalized Children With Severe Acute Respiratory Infection

BACKGROUND

To evaluate the enterovirus (EV)-positivity rate in respiratory samples collected from children ≤15 years hospitalized with severe acute respiratory infections (SARIs) and to describe the epidemiologic and molecular characteristics of EVs.

METHODS

Respiratory samples were collected from 2468 children hospitalized with SARI at a university and research hospital in Milan (September 1, 2014 to August 31, 2017). EV and EV-D68 RNA were detected using a commercial multiplex and a specific real-time RT-PCR assay, respectively. The EV-D68-negative samples were then characterized by partial sequencing of the VP1 gene.

RESULTS

EV-RNA was detected in 9% (222/2468) of SARI cases, 77% were children ≤3 years, almost 13% of whom required intensive care. EVs circulated all-year-round in 2 distinct epidemic waves (May-August and November-December). An EV-D68 outbreak, responsible for 14.8% of EV-positive-SARIs, occurred in 2016 and 5 newly emerging EV types were identified. Twenty-two EV types were detected and remarkable heterogeneity was observed in species distribution and between different pediatric age groups.

CONCLUSIONS

This study showed that EV-positivity rate for our SARI series was 9%. The molecular detection and characterization of EVs allowed for the rapid detection of an EV-D68 outbreak and revealed the presence of emerging EV types that may pose a public health threat. The lack of routine screening and EV characterization in respiratory tract infections hampers the assessment of their epidemiologic and molecular features.

Enterovirus D68 Subclade B3 Circulation in Senegal, 2016: Detection from Influenza-like Illness and Acute Flaccid Paralysis Surveillance

Following the 2014 outbreak, active surveillance of the EV-D68 has been implemented in many countries worldwide. Despite subsequent EV-D68 outbreaks (2014 and 2016) reported in many areas, EV-D68 circulation remains largely unexplored in Africa except in Senegal, where low levels of EV-D68 circulation were first noted during the 2014 outbreak. Here we investigate subsequent epidemiology of EV-D68 in Senegal from June to September 2016 by screening respiratory specimens from ILI and stool from AFP surveillance. EV-D68 was detected in 7.4% (44/596) of patients; 40 with ILI and 4 with AFP. EV-D68 detection was significantly more common in children under 5 years (56.8%, p = 0.016). All EV-D68 strains detected belonged to the newly defined subclade B3. This study provides the first evidence of EV-D68 B3 subclade circulation in Africa from patients with ILI and AFP during a 2016 outbreak in Senegal. Enhanced surveillance of EV-D68 is needed to better understand the epidemiology of EV-D68 in Africa.

Case fatality rate and viral aetiologies of acute respiratory tract infections in HIV positive and negative people in Africa: The VARIAFRICA-HIV systematic review and meta-analysis

BACKGROUND

To set priorities for efficient control of acute respiratory tract infection (ARTI) in Africa, it is necessary to have accurate estimate of its burden, especially among HIV-infected populations.

OBJECTIVES

To compare case fatality rate (CFR) and viral aetiologies of ARTI between HIV-positive and HIV-negative populations in Africa.

STUDY DESIGN

We searched PubMed, EMBASE, Web of Knowledge, Africa Journal Online, and Global Index Medicus to identify studies published from January 2000 to April 2018. Random-effect meta-analysis method was used to assess association (pooled weighted odds ratios (OR) with 95% confidence interval (CI)).

RESULTS

A total of 36 studies (126,526 participants) were included. CFR was significantly higher in patients with HIV than in HIV-negative controls (OR 4.10, 95%CI: 2.63-6.27, I²: 93.7%). The risk was significantly higher among children ≤5 years (OR 5.51, 95%CI 2.83-10.74) compared to people aged >5 years (OR 1.48, 95%CI 1.17-1.89); p = 0.0002. There was no difference between children (15 years) and adults and between regions of Africa. There was no difference for viral respiratory aetiologies (Enterovirus, Adenovirus, Bocavirus, Coronavirus, Metapneumovirus, Parainfluenza, Influenza, and Respiratory Syncytial Virus) of ARTI between HIV-positive and HIV-negative people, except for Rhinovirus where being HIV-negative was associated with Rhinovirus (OR 0.70; 95%CI 0.51-0.97, I²: 63.4%).

CONCLUSIONS

This study shows an increased risk of deaths among HIV-infected individuals with ARTI, however with no difference in viral aetiologies compared to HIV-negative individuals in Africa. ARTI deserves more attention from HIV health-care providers for efficient control. Specific strategies are needed for HIV-positive children under 5.

A neonatal mouse model of Enterovirus D68 infection induces both interstitial pneumonia and acute flaccid myelitis

Enterovirus D68 (EV-D68) is a causative agent of recent outbreaks of severe respiratory illness, pneumonia and acute flaccid myelitis (AFM) worldwide. The study of the pathogenesis, vaccines and anti-viral drugs for EV-D68 infection has been reported. Given the previously described mouse model of EV-D68, we sought to establish a neonatal mice model inducing both pneumonia and AFM. The neonatal BALB/c mice were inoculated intraperitoneally with the EV-D68 strain (named15296-virus) which was produced by the reverse genetics method. The infected mice displayed limb paralysis, tachypnea and even death, which were similar to the clinical symptoms of human infections. Moreover, the results of histopathologic examination and immunohistochemical staining showed acidophilic necrosis in the muscle, the spinal cord and alveolar wall thickening in the lung, indicating that EV-D68 exhibited strong tropism to the muscles, spinal cord and lung. Furthermore, the results of real-time PCR also suggested that the viral loads in the blood, spinal cord, muscles and lung were higher than those in other tissues at different time points post-infection. Additionally, the neonatal mouse model was used for evaluating the EV-D68 infection. The results of the anti-serum passive and maternal antibody protection indicated that the neonatal mice could be protected against the EV-D68 challenge, and displayed that both the serum of 15296-virus and prototype-virus (Fermon) were performing a certain cross-protective activity against the 15296-virus challenge. In summary, the above results proved that our neonatal mouse model possessed not only the interstitial pneumonia and AFM simultaneously but also a potentiality to evaluate the protective effects of EV-D68 vaccines and anti-viral drugs in the future.

Enterovirus genotypes among patients with severe acute respiratory illness, influenza-like illness, and asymptomatic individuals in South Africa, 2012-2014

Enteroviruses can cause outbreaks of severe acute respiratory illness (SARI) and EV-A, -B, -C, and -D species have different pathogenic profiles and circulation patterns. We aimed to characterize and determine the prevalence of enterovirus genotypes among South African patients with respiratory illness and controls during June 2012 to July 2014. Syndromic SARI and influenza-like illness (ILI) surveillance was performed at two sentinel sites. At each site nasopharyngeal/oropharyngeal specimens were collected from SARI and ILI patients as well as controls. Specimens were tested for enterovirus by real-time PCR. Positive specimens were further genotyped by sequencing a region of the VP1 gene. The prevalence of enterovirus was 5.8% (87/1494), 3.4% (103/3079), and 3.4% (46/1367) among SARI, ILI, and controls, respectively (SARI/controls, P = 0.002 and ILI/control, P = 0.973). Among the 101/236 (42.8%) enterovirus-positive specimens that could be genotyped, we observed a high diversity of circulating enterovirus genotypes (a total of 33 genotypes) from all four human enterovirus species with high prevalence of Enterovirus-B (60.4%; 61/101) and Enterovirus-A (21.8%; 22/101) compared to Enterovirus-C (10.9%; 11/101) and Enterovirus-D (6.9%; 7/101) (P = 0.477). Of the enterovirus genotypes identified, Echovirus 30 (9.9%, 10/101), Coxsackie virus B5 (7.9%, 8/101) and Enterovirus-D68 (6.9%, 7/101) were most prevalent. There was no difference in disease severity (SARI or ILI compared to controls) between the different enterovirus species (P = 0.167). We observed a high number of enterovirus genotypes in patients with respiratory illness and in controls from South Africa with no disease association of EV species with disease severity.