RESUMEN

Typhoid fever is a significant global health problem that impacts people living in areas without access to clean water and sanitation. However, collaborative international partnerships and new research have improved both knowledge of the burden in countries with endemic disease and the tools for improved surveillance, including environmental surveillance. Two typhoid conjugate vaccines (TCVs) have achieved World Health Organization prequalification, with several more in the development pipeline. Despite hurdles posed by the coronavirus disease 2019 pandemic, multiple TCV efficacy trials have been conducted in high-burden countries, and data indicate that TCVs provide a high degree of protection from typhoid fever, are safe to use in young children, provide lasting protection, and have the potential to combat typhoid antimicrobial resistance. Now is the time to double down on typhoid control and elimination by sustaining progress made through water, sanitation, and hygiene improvements and accelerating TCV introduction in high-burden locations.

RESUMEN

The 11th African Rotavirus Symposium was held in Lilongwe, Malawi from May 28th to 30th 2017. Over 270 delegates (73% from Africa) from 40 countries of which 30 (75%) were from African countries attended the symposium. Participants in this symposium included research scientists, clinicians, immunization managers, public health officials, policymakers and vaccine manufacturers. At the time of the symposium, 38 of the 54 (70%) countries in Africa had introduced rotavirus vaccines into their national immunization schedules. Delegates shared progress from rotavirus surveillance and vaccine impact monitoring, demonstrating the impact of the vaccine against rotavirus diarrheal hospitalizations. Data supported the beneficial effect and safety of WHO pre-qualified available vaccines up to 2017 (RotaTeq, Rotarix). This symposium highlighted the dramatic impact of the rotavirus vaccination, called for urgent adoption of these vaccines in remaining countries, particularly those with high disease burden and large birth cohorts (e.g. Nigeria, Democratic Republic of Congo) to attain the full public health benefits of rotavirus vaccination in Africa.

Asunto(s)

Diarrea/prevención & control , Programas de Inmunización , Infecciones por Rotavirus/prevención & control , Vacunas contra Rotavirus/administración & dosificación , África , Congresos como Asunto , Diarrea/virología , Hospitalización , Humanos , Esquemas de Inmunización , Malaui , Rotavirus , Vacunación

RESUMEN

Rotavirus A (RVA) exhibits a wide genotype diversity globally. Little is known about the genetic composition of genotype P[6] from Africa. This study investigated possible evolutionary mechanisms leading to genetic diversity of genotype P[6] VP4 sequences. Phylogenetic analyses on 167 P[6] VP4 full-length sequences were conducted, which included six porcine-origin sequences. Of the 167 sequences, 57 were newly acquired through whole genome sequencing as part of this study. The other 110 sequences were all publicly-available global P[6] VP4 full-length sequences downloaded from GenBank. The strength of association between the phenotypic features and the phylogeny was also determined. A number of reassortment and mixed infections of RVA genotype P[6] strains were observed in this study. Phylogenetic analyses demostrated the extensive genetic diversity that exists among human P[6] strains, porcine-like strains, their concomitant clades/subclades and estimated that P[6] VP4 gene has a higher substitution rate with the mean of 1.05E-3 substitutions/site/year. Further, the phylogenetic analyses indicated that genotype P[6] strains were endemic in Africa, characterised by an extensive genetic diversity and long-time local evolution of the viruses. This was also supported by phylogeographic clustering and G-genotype clustering of the P[6] strains when Bayesian Tip-association Significance testing (BaTS) was applied, clearly supporting that the viruses evolved locally in Africa instead of spatial mixing among different regions. Overall, the results demonstrated that multiple mechanisms such as reassortment events, various mutations and possibly interspecies transmission account for the enormous diversity of genotype P[6] strains in Africa. These findings highlight the need for continued global surveillance of rotavirus diversity.

Asunto(s)

Genotipo , Infecciones por Rotavirus/epidemiología , Infecciones por Rotavirus/virología , Rotavirus/genética , Secuenciación Completa del Genoma , África/epidemiología , Heces/virología , Humanos , Filogenia , Virus Reordenados/genética

RESUMEN

The human, G1P[8] rotavirus vaccine (Rotarix™) significantly reduced severe rotavirus gastroenteritis episodes in a clinical trial in South Africa and Malawi, but vaccine efficacy was lower in Malawi (49.5%) than reported in South Africa (76.9%) and elsewhere. The aim of this study was to examine the molecular relationships of circulating wild-type rotaviruses detected during the clinical trial in Malawi to RIX4414 (the strain contained in Rotarix™) and to common human rotavirus strains. Of 88 rotavirus-positive, diarrhoeal stool specimens, 43 rotaviruses exhibited identifiable RNA migration patterns when examined by polyacrylamide gel electrophoresis. The genes encoding VP7, VP4, VP6 and NSP4 of 5 representative strains possessing genotypes G12P[6], G1P[8], G9P[8], and G8P[4] were sequenced. While their VP7 (G) and VP4 (P) genotype designations were confirmed, the VP6 (I) and NSP4 (E) genotypes were either I1E1 or I2E2, indicating that they were of human rotavirus origin. RNA-RNA hybridization using 21 culture-adapted strains showed that Malawian rotaviruses had a genomic RNA constellation common to either the Wa-like or the DS-1 like human rotaviruses. Overall, the Malawi strains appear similar in their genetic make-up to rotaviruses described in countries where vaccine efficacy is greater, suggesting that the lower efficacy in Malawi is unlikely to be explained by the diversity of circulating strains.

Asunto(s)

Variación Genética , Infecciones por Rotavirus/epidemiología , Infecciones por Rotavirus/virología , Vacunas contra Rotavirus/administración & dosificación , Rotavirus/clasificación , Análisis por Conglomerados , Electroforesis en Gel de Poliacrilamida , Heces/virología , Genes Virales , Genotipo , Humanos , Malaui/epidemiología , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Filogenia , ARN Viral/genética , Rotavirus/genética , Rotavirus/aislamiento & purificación , Infecciones por Rotavirus/prevención & control , Vacunas contra Rotavirus/inmunología , Análisis de Secuencia de ADN

RESUMEN

Rotavirus is responsible for more than half a million deaths among infants and young children worldwide each year; many of these deaths could be prevented by widespread use of an effective rotavirus vaccine. The diversity of rotavirus strains in many developing countries, where most rotavirus deaths occur, could represent a significant challenge to the efficacy of current vaccines. In anticipation of rotavirus vaccine introduction, we examined studies published over a 10-year period (1997-2006) from countries in Africa that examined the distribution of VP7 (G) and VP4 (P) rotavirus strain types in symptomatic children and in neonates, together with studies that undertook a more detailed characterization of unusual rotavirus strains. Compared with recently published global reviews of rotavirus strain types and a previous review of the African literature published before 1997, the current data indicate a substantially increased diversity of rotavirus strains across the continent. Notable findings included a reduction in the proportion of globally common serotypes; a high proportion of unusual P/G combinations, suggesting viral reassortment; evidence for zoonotic rotavirus transmission; the emergence and spread across Africa of serotype G9; and a high prevalence of the P[6] VP4 genotype. These data imply that rotavirus vaccines will need to confer protection against a wide variety of strain types in Africa and emphasize the importance of continued strain surveillance before and after the introduction of routine rotavirus vaccination.

Asunto(s)

Infecciones por Rotavirus/epidemiología , Infecciones por Rotavirus/virología , Rotavirus/clasificación , África/epidemiología , Genoma Viral , Humanos , Rotavirus/genética , Rotavirus/inmunología , Infecciones por Rotavirus/prevención & control , Vacunas contra Rotavirus

RESUMEN

<p><b>OBJECTIVE</b>To learn the epidemiologic characteristics of rotavirus diarrhea in three hospitals under sentinel surveillance from August 2001 to July 2004 and to provide background information for developing and implementing rotavirus vaccine.</p><p><b>METHODS</b>Data from hospital-based rotavirus surveillance among children < 5 years old hospitalized with acute diarrhea was used. Patients' clinic information and feces specimens were collected. Specimens were tested and typed for rotavirus.</p><p><b>RESULTS</b>Totally, 3121 specimens were tested and the detection rate of rotavirus was 51%. Among all the children with rotavirus diarrhea, 94% were < 2 years old. G3 (69.9%) was the most prevalent serotype followed by G1 (6.6%) and G2 (2.9%). P[8] was the most common genotype of rotavirus. The most common G-P combination identified in this study was P[8] G3 (64.0%). Seveal other combinations of minor frequency were also identified.</p><p><b>CONCLUSION</b>Rotavirus infection was most commonly seen among children < 5 years old hospitalized with acute diarrhea in the three hospitals. It is important to develop and implement rotavirus vaccine to prevent and control severe rotavirus infection. Because of the diversity of rotavirus strains, it is necessary to perform rotavirus strain surveillance to understand the dynamic nature of viral transmission.</p>

Asunto(s)

Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , China , Epidemiología , Diarrea , Epidemiología , Virología , Heces , Virología , Hospitales , Infecciones por Rotavirus , Epidemiología , Virología , Vigilancia de Guardia

RESUMEN

Human calicivirus (HuCV) has been well known as an important pathogen of outbreak and sporadic acute nonbacterial gastroenteritis worldwide. To investigate epidemiological feature and genetic diversity of HuCV among children in China, fecal specimens were collected from children under 5 years of age with acute diarrhea at 13 hospitals in different provinces across China. The study was performed year-round from January 1999 to June 2005. Fecal specimens were tested for bacteria and rotavirus first and the negative specimens then were tested for HuCV using ELISA and RT-PCR. PCR amplicons were cloned and sequenced for strain characterization. A total of 4426 rotavirus- negative fecal samples were screened. From these, 840 (19%) were positive for HuCV by either or both ELISA (14%) and RT-PCR (9.6%). HuCV infection occurred year-round with an epidemic in each winter (October-January) and mainly in children at 6 -- 17 months of age. Of 151 HuCV strains characterized, 146 belong to norovirus (NV, 96.7%) and 5 were sapoviruses (SV). Among norovirus strains, genotype GG II/4 was most common (99/146), followed by GG II/3 (22/146), GG II/5 (8/146), and 2 strains of each of GG II/6, GG II/7, GG II/8, and GG I/2, the other 9 strains of NV GG II were unique, potentially belonging to new genotypes. These results plus the epidemiology data suggested that HuCVs are an important cause of severe diarrhea in Chinese children that were under reported due to a lack of a simple diagnostic assay. The finding of the potential new genotypes indicates that the current assays need to be improved for broader detection and besides, a continual surveillance for better understanding the epidemiology the disease burden and the searching for new strains of HuCVs is necessary.

Asunto(s)

Preescolar , Humanos , Lactante , Recién Nacido , Distribución por Edad , Caliciviridae , Clasificación , Genética , Infecciones por Caliciviridae , Epidemiología , Patología , Virología , China , Epidemiología , ARN Polimerasas Dirigidas por ADN , Genética , Metabolismo , Diarrea , Epidemiología , Virología , Ensayo de Inmunoadsorción Enzimática , Heces , Virología , Filogenia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Proteínas Virales , Genética , Metabolismo

RESUMEN

<p><b>OBJECTIVE</b>To study molecular epidemiology of four major etiological viruses among children with acute diarrhea in Lanzhou, Gansu province.</p><p><b>METHODS</b>Stool specimens were collected from all 400 inpatients less than 5 years old with acute diarrhea admitted in Department of Pediatrics, the First Hospital, Lanzhou University from Jul. 2004 through Jun. 2005. Dako IDEIA kits were used for detection of rotavirus, adenovirus and astrovirus. Calicivirus detection was done by both reverse transcription-polymerase chain reactions (RT-PCR) and ELISA. Further strain characterization of rotavirus and astrovirus was carried out with RT-PCR.</p><p><b>RESULTS</b>A total of 400 stool samples were collected and tested. Rotavirus was present in 47.3% of the cases: calicivirus in 15.5%, astrovirus in 9.5% and adenoviruses in 7.5%. Mixed infections with multiple enteric viruses were present in 13.5% of all samples. Among 189 rotavirus positive samples, serotype G2 (34.4%) was the predominant strain followed by G3 (32.8%), G1 (1.1%) and mixed-G infection (5.8%). 25.9% of strains remained to be non-typeable. P genotyping showed P [4] (45%) was most common followed by P [8] (22.1%), and non-typeable (32.9%). Strain P [4] G2 (43.6%) was the most common combination followed by P [8] G3 (25.6%), P [4] G3 (13.8%), and P [8] G2, P [4] G1 and P [8] G1. Among 38 astrovirus strains, serotypes 1 (57.8%) was the predominant. Serotype 3 and 8 were found only in one case respectively, 14 strains remained to be non-typeable. A peak admission of rotavirus diarrhea was observed from October through December. More than 95.0% of viral diarrhea patients under hospitalization occurred among children younger than 2 years. The incidence rates of rotavirus were highest in infants aged 6 - 23 months.</p><p><b>CONCLUSION</b>Rotavirus was the most important pathogen for viral diarrhea among children hospitalized in Lanzhou followed by calicivirus, astrovirus, and adenovirus. The predominant rotavirus strain circulated was P [4] G2, which was different from the finding in the previous years. The high rate of mixed infection with different viral agents was notable.</p>

Asunto(s)

Preescolar , Humanos , Lactante , Enfermedad Aguda , Adenoviridae , Clasificación , Genética , Caliciviridae , Clasificación , Genética , China , Epidemiología , Diarrea , Virología , Ensayo de Inmunoadsorción Enzimática , Heces , Virología , Mamastrovirus , Clasificación , Genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Rotavirus , Clasificación , Genética , Serotipificación , Virosis , Epidemiología , Genética

RESUMEN

<p><b>OBJECTIVE</b>To study the epidemiology and strain variations of astrovirus infection among children under 5 years of age, hospitalized for acute diarrhea in China.</p><p><b>METHODS</b>Inpatients under 5 years of age with acute diarrhea in hospitals of seven provinces between 1998 and 2005 were enrolled in the study Stool specimens were collected and tested for astrovirus using the Dako Amplified IDEIA Astrovirus kits or reverse-transcription polymerase chain reaction (RT-PCR). Genetic identities of the strains were determined using RT-PCR with serotype-specific primers and confirmed by sequencing of the RT-PCR products.</p><p><b>RESULTS</b>A total of 1668 diarrheal stool samples tested for both rotavirus and calicivirus negative were examined. The detection rate of astrovirus infection was 5.5% (91/1668) and the diarrhea cases caused by astrovirus infection could be found in any season of the year but mainly occurred in cold season from October to next January. Astrovirus detection-rates were: 7.4% among infants aged 9-11 months followed by 6.1% in 12-17 month-olds, and 6-8 months 5.6% & 0-2 months 5.6% before 8 months. Over 95% of astrovirus infections occurred in children before 2 years of age. Among 49 strains, typed, serotype 1(45/91) was most commonly seen while serotype 5 was in two cases and serotype 3 and 8 were detected in only one case respectively.</p><p><b>CONCLUSION</b>Astrovirus seemed an important etiologic agent in young children with acute diarrhea in China and Serotype 1 was the most prevalent one.</p>

Asunto(s)

Preescolar , Humanos , Lactante , Recién Nacido , Enfermedad Aguda , Astroviridae , Clasificación , Infecciones por Astroviridae , Epidemiología , China , Epidemiología , ADN Viral , Diarrea , Virología , Pacientes Internos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Estaciones del Año , Serotipificación

Asunto(s)

Inmunización , Rotavirus