Circulation patterns and molecular epidemiology of human respiratory syncytial virus over five consecutive seasons in Morocco.

Background: Respiratory syncytial virus (HRSV) is the leading cause of respiratory tract infections in infants and young children. we investigated the prevalence and characteristics of HRSV in Morocco and explored trends in circulating genotypes through partial G gene analysis of HRSV strains prevalent from 2012 to 2017. Methods: Respiratory samples were gathered from both outpatients and inpatients meeting ILI or SARI case definitions. The patients' ages varied from 1 month to 99 years old. Nucleic acids were extracted and HRSV type/subtype was detected by RT-qPCR. A subset of positive samples was randomly selected in each epidemic year, the complete viral genome was sequenced, phylogenetic analysis was performed using the MEGA7 program and the genotypes were confirmed. Results: The 3679 specimens were collected from 2012 to 2017, of which 726 (19.7%) were positive for HRSV. The 35% (257/726) of HRSV-positives were of the HRSV-A subtype, while the HRSV-B subtype accounted for 61% (442/726). The co-infection rate was 3.7% (27/726). The virus circulates in a periodic pattern, where epidemics occur during the fall months through early spring. HRSV genotype was confirmed in 127 specimens (56 HRSV-A and 71 HRSV-B). Based on phylogenetic analysis, all HRSV-A were ON1 genotype, and HRSV-B were mostly BA9 genotype. HRSV-B belonging to the BA10 genotype was detected in 2012 exclusively. Conclusions: BA9, BA10, and ON1 were the only HRSV genotypes detected between 2012 and 2017. Variations in the G gene amino acid chain were identified in local strains, which suggests an increased need for continuous genomic surveillance.

Factors associated with hospitalization for seasonal influenza in Morocco.

Background: Morocco is actively working towards expanding its influenza vaccine policy to cover high-risk groups, as recommended by the World Health Organization (WHO). Aims: We assessed the risk factors for influenza-associated hospitalization for severe acute respiratory infections (SARI) that occurred during the last 5 seasons. Methods: We conducted a retrospective, analytical study among patients recruited in the ambulatory and hospital sites of the influenza sentinel surveillance system in Morocco between 2014 and 2019. Using multiple logistic regression, we compared the characteristics of influenza-positive patients with SARI to those with influenza-like illness (ILI) to identify factors associated with severe disease. Results: We included 1323 positive influenza patients with either SARI (41.7%) or ILI diagnosis (58.3%). A(H1N1)pdm09, A(H3N2) and influenza B, respectively, contributed 49.2%, 29.5% and 20.6% of the cases. The main risk factors considered in the bivariate analysis were found in the multivariate analysis to be significantly associated with influenza-related hospitalization (SARI): age < 2 years (aOR = 7.08, P < 0.001); age ≥ 65 years (aOR = 3.59, P < 0.001); diabetes (aOR = 1.98, P = 0.017); obesity (aOR = 2.94, P = 0.034); asthma or chronic respiratory disease (aOR = 4.99, P < 0.001); chronic renal failure (aOR = 4.74, P = 0.005); pregnancy (aOR = 7.49, P < 0.001); and the A(H1N1)pdm09 subtype (aOR = 1.82, P < 0.001). Conclusion: This study provides epidemiological evidence for the expected benefit of an influenza vaccination strategy for high-risk groups as recommended by the WHO.

Viral aetiology of influenza-like illnesses and severe acute respiratory illnesses in Morocco, September 2014 to December 2016.

Background: There is a scarcity of information on the viral aetiology of influenza-like illness (ILI) and severe acute respiratory infection (SARI) among patients in Morocco. Methods: From September 2014 to December 2016, we prospectively enrolled inpatients and outpatients from all age groups meeting the World Health Organization (WHO) case definition for ILI and SARI from 59 sentinel sites. The specimens were tested using real-time monoplex reverse-transcription polymerase chain reaction method for detecting 16 relevant respiratory viruses. Results: At least one respiratory virus was detected in 1423 (70.8%) of 2009 specimens. Influenza viruses were the most common, detected in 612 (30.4%) of processed samples, followed by respiratory syncytial virus (RSV) in 359 (17.9%), human rhinovirus (HRV) in 263 (13.1%), adenovirus (HAdV) in 124 (6.2%), parainfluenza viruses (HPIV) in 107 (5.3%), coronaviruses (HCoV) in 94 (4.7%), human bocavirus (HBoV) in 92 (4.6%), and human metapneumovirus (HMPV) in 74 (3.7%). From 770 samples from children under 5 years old, RSV (288, 36.6%), influenza viruses (106, 13.8%), HRV (96, 12.5%) and HAdV (91, 11.8%) were most prevalent. Among 955 samples from adults, Influenza viruses (506, 53.0%), and HRV (167, 17.5%) were most often detected. Co-infections were found in 268 (18.8%) of 1423 positive specimens, and most (60.4%) were in children under 5 years of age. While influenza viruses, RSV, and HMPV had a defined period of circulation, the other viruses did not display clear seasonal patterns. Conclusions: We found that RSV was predominant among SARI cases in Morocco, particularly in children under 5 years of age. Our results are in line with reported data from other parts of the world, stating that RSV is the leading cause of lower respiratory tract infections in infants and young children.

Real-Time PCR for Measles Virus Detection on Clinical Specimens with Negative IgM Result in Morocco.

Since the confirmation of measles cases represents an important indicator regarding the performance of the measles-elimination program, the aim of this study was to evaluate the effectiveness of the routine procedures followed in Morocco for the laboratory confirmation of measles cases. Suspected cases reported between January 2010 and December 2012 were assessed for the timeliness of the sample collection, occurrence of measles clinical symptoms, and the results of the laboratory diagnoses. For 88% of the 2,708 suspected cases, a clinical specimen was collected within 7d of rash onset, of which 50% were IgM-positive and 2.6% were equivocal. The measles symptoms were reported in 91.4% of the cases; the occurrence of symptoms showed a positive association with the serological results (odds ratio [OR] = 2.9883, 95% confidence interval [CI] 2.2238-4.0157). Of the negative samples, 52% (n = 116) tested positive by real-time polymerase chain reaction (PCR). These results are in favor of using molecular detection to complement serological diagnosis in the context of measles surveillance approach in Morocco. In addition, the introduction of additional laboratory methods for differential diagnosis is required for the final classification of suspected cases with maculopapular rash and fever in the context of the measles elimination program.