Effect of monovalent rotavirus vaccine on rotavirus disease burden and circulating rotavirus strains among children in Morocco.

Rotarix(TM) vaccine was introduced into the National Program of Immunization of Morocco in October 2010, reaching quickly 87% of the target population of children nationally. The incidence of rotavirus gastroenteritis and the prevalence of circulating rotavirus strains has been monitored in three sentinel hospitals since June 2006. The average percentage of rotavirus positive cases among all children under 5 years old hospitalized for gastroenteritis during the pre-vaccine period (2006-2010) was 44%. This percentage dropped to 29%, 15% and 24% in the 3 years post vaccine introduction (2011, 2012 and 2013), which is a decline of 34%, 66%, and 45%, respectively. Declines in prevalence were greatest among children 0-1 years of age (53%) and were most prominent during the winter and autumn rotavirus season. The prevalence of the G2P[4] and G9P[8] genotype sharply increased in the post vaccine period (2011-2013) compared to the previous seasons (2006-2010). Rotavirus vaccines have reduced greatly the number of children hospitalized due to rotavirus infection at the three sentinel hospitals; it is however unclear if the predominance of G2P[4] and G9P[8] genotypes is related to the vaccine introduction, or if this is attributable to normal genotype fluctuations. Continued surveillance will be pivotal to answer this question in the future.

Diversity of rotavirus strains circulating in children under 5 years of age admitted to hospital for acute gastroenteritis in Morocco, June 2006 to May 2009.

Rotavirus vaccine was introduced in Morocco during 2010. In anticipation of introducing rotavirus vaccines, the Ministry of Health in Morocco established a rotavirus surveillance network in June 2006 at four hospitals in Morocco to obtain baseline data on rotavirus disease burden and prevalent strains. From June 2006 to May 2009, stool samples were collected from children under 5 years of age admitted for diarrhea to four sentinel hospitals serving different regions of Morocco. Rotaviruses were detected in stools using enzyme immunoassay, then genotyped by reverse-transcriptase polymerase chain reaction. Samples with adequate stool in which the P or G types could not be determined by RT-PCR were subjected to nucleotide sequence analysis. Overall, 42% (579 of 1,388) of the stools samples tested were positive for rotavirus. Genotyping of 548 (95%) samples demonstrated that G1P[8] (55%) was the most prevalent strain, followed by G9P[8] (11.3%), G2P[4] (9.1%), G4P[8] (0.9%), and G3P[8] (0.4%). Several other strains were identified including G1P[4] (0.2%), G1P[6] (0.9%), G2P[6] (4.3%), G2P[8] (0.2%), G3P[6] (0.4%), G3P[4] (0.2%), and G9P[6] (0.2%). A high prevalence of mixed infections was found (15% of all samples) of which G1G2P[8] (4%) and G1G3P[8] (3.6%) accounted for the majority. Considerable diversity of rotavirus genotypes was present among strains circulating in Morocco prior to the introduction of the vaccine. This study highlighted the need for maintaining active surveillance to monitor changes in rotavirus disease burden and strain dynamics and to detect changes over time that could impact the effectiveness of the vaccination program.

Epidemiology of rotavirus gastroenteritis among children <5 years of age in Morocco during 1 year of sentinel hospital surveillance, June 2006-May 2007.

BACKGROUND: In anticipation of vaccine introduction, we assessed the epidemiology, burden, and genotype of infecting strains of rotavirus disease among Moroccan children hospitalized for acute gastroenteritis. METHODS: From June 2006 through May 2007, 345 children <5 years of age who had acute gastroenteritis and were admitted to 4 sentinel hospitals in different regions of Morocco were enrolled in this surveillance study, and stool specimens were tested for the presence of rotavirus with use of enzyme immunoassay. RNA from positive samples was genotyped by reverse-transcriptase polymerase chain reaction. RESULTS: Overall, 314 children had complete data available, and among these, 138 (44%) tested positive for rotavirus. Rotavirus infection was most common among children <24 months of age (95% of all hospitalizations for rotavirus infection). Rotavirus infection was detected year-round at all 4 sites but was most prevalent from September through January. Genotype analysis demonstrated that 30.6% of samples were G1[P8], 26% were G9[P8], 7.5% were G2[P6], 3.7% were G1[P6], and 0.7% were G2[P8]. Nucleotide sequencing analysis of G- or P-untypeable strains showed that 4.5% were G9[P8], 2.2% were G1[8], 2.2% were G2[P6], and 1.5% were G2[P4]. A high frequency of mixed infection (21%) was found, of which G1G2[P8] accounted for the majority (16.4%). CONCLUSIONS: Rotavirus was responsible for 44% of all hospitalizations for diarrhea among young children at these 4 separate sites in Morocco. These data will help inform a decision on the introduction of rotavirus vaccine in Morocco. Continued and extended surveillance in Morocco will be important to monitor changes in the epidemiology of rotavirus disease and the impact of vaccination after introduction.

Reduction of hospitalizations with diarrhea among children aged 0-5 years in Nouakchott, Mauritania, following the introduction of rotavirus vaccine.

INTRODUCTION: Rotavirus vaccine was introduced in Mauritania in December 2014. We investigated hospitalizations with diarrhea during pre and post-vaccination periods among children aged 0-5 years in Nouakchott, the capital of Mauritania. METHODS: We conducted a retrospective review of hospital admission registries from November 1st 2012 through October 31th 2017 at all referral hospitals in Nouakchott. We described admissions of children aged 0-5 years by diagnosis, data of admission, age and sex, and compared the proportion of all childhood hospitalizations with diarrhea before and after rotavirus vaccine introduction. RESULTS: In total, 6552 (19%) of all 34,329 hospitalizations in 0-5 year-olds had diarrhea. Of these, 3523/16,952 (20.7%) were recorded during the pre-vaccine period, 1373/6897 (19.9%) during the transition period (November 2014-October 2015), and 1656/10,480 (15.8%) during the post-vaccination period. The proportion of all childhood hospitalizations with diarrhea during the pre-vaccine period was 22.6% among males and 18.7% among females. Approximately one third (32.3%) of hospitalizations with diarrhea occurred in children aged 6-11 months. During the post-vaccination period, the proportion of hospitalizations with diarrhea declined by 24%, and the highest reduction (74%) was observed in children aged 2 to 5 years (P < 0.001). CONCLUSIONS: The proportion of childhood hospitalizations with diarrhea in Nouakchott was reduced by about one fourth after introduction of rotavirus vaccination in Mauritania, indicating a major impact for public health for children in the capital city.

Hospitalizations and Deaths Associated with Diarrhea and Respiratory Diseases among Children Aged 0⁻5 Years in a Referral Hospital of Mauritania.

Diarrhea and respiratory diseases are the leading causes of morbidity and mortality among <5-year-olds worldwide, but systematic data are not available from Mauritania. We conducted a hospital-based retrospective study. Data on admissions to Mauritania's National Referral Hospital (the main pediatric referral center in the country), due to diarrhea and respiratory diseases, during 2011⁻2014, were analyzed. A total of 3695 children <5 years were hospitalized during this period; 665 (18.0%) due to respiratory diseases, and 829 (22.4%) due to diarrhea. Case fatality rates in the respiratory diseases and diarrhea groups were 18.0% (120/665) and 14.1% (117/829), respectively. The highest frequency of deaths due to diarrhea occurred in the age group 2⁻5 years (16/76; 21.0%), and due to respiratory diseases in the age group 6⁻12 months (32/141; 22.6%). We conclude that case fatality rates caused by respiratory diseases and diarrhea are extremely high in children hospitalized at the National Referral Hospital. These data call for intensified efforts to reduce deaths among hospitalized Mauritanian children, and also for integrated control measures to prevent and reduce the burden of both diseases. Additional studies are needed to show the effectiveness of the introduction of vaccination programs for pneumococcal diseases and rotavirus infection in the child population, which were launched in November 2013 and December 2014, respectively.

Monitoring of rotavirus vaccination in Morocco: establishing the baseline burden of rotavirus disease.

BACKGROUND: Rotavirus is a leading cause of childhood morbidity and mortality worldwide. Clinical trials for two rotavirus vaccines recommended by the WHO for global use since 2009 have successfully demonstrated the safety and efficacy of these vaccines in a wide range of countries. To control the burden of severe and fatal diarrheal disease, the Ministry of Health of Morocco introduced the single strain rotavirus vaccine into their national immunization program in 2010. METHODS: We employed a standard WHO case definition to identify children under 5 hospitalized with AGE at four hospitals from June 2006 to May 2010 to establish baseline burden of rotavirus disease before introduction of vaccine. Stool samples were collected and tested for rotavirus using a standard enzyme immunoassay. RESULTS: Overall, 40% (741 of 1841) of the children hospitalized with AGE tested positive for rotavirus, making it the single most common cause of severe gastroenteritis among children in Morocco. Applying this prevalence to the estimates of diarrheal hospitalizations and deaths in Morocco, we estimate that rotavirus annually causes 19,646 hospitalizations and 1604 deaths in children under 5 years of age. DISCUSSION: On the basis of these surveillance data, we estimate that 1 in 389 Moroccan children died and 1 in 32 was hospitalized due to rotavirus before their fifth birthday. A considerable proportion of these deaths and hospitalizations should be preventable through vaccination, and the 4 years of stable prevaccine surveillance in Morocco will be a tremendously useful platform for assessing potential changes in the epidemiology of rotavirus disease and measuring impact of the new rotavirus vaccine program in Morocco.