Norovirus diarrhea is significantly associated with higher counts of fecal histo-blood group antigen expressing Enterobacter cloacae among black South African infants

The study tested the hypothesis that harboring high levels of histo-blood group antigen-expressing Enerobactero cloacae is a risk factor for norovirus diarrhea. The fecal E. cloacae abundance in diarrheic norovirus positive (DNP), non-diarrheic norovirus negative (NDNN), diarrhea norovirus negative (DNN), and non-diarrhea norovirus positive (NDNP) infants was determined by qPCR, and the risk of norovirus diarrhea was assessed by logistical regression. DNP infants contained significantly higher counts of E. cloacae than NDNN and DNN infants, p = .0294, and 0.0001, respectively. The risk of norovirus diarrhea was significantly high in infants with higher counts of E. cloacae than those with lower counts, p = .009. Harboring higher counts of E. cloacae is a risk factor for norovirus diarrhea.

Evaluation of Potency and Duration of Immunity Elicited by a Multivalent FMD Vaccine for Use in South Africa

South Africa (SA) experiences sporadic foot and mouth disease (FMD) outbreaks irrespective of routine prophylactic vaccinations of cattle using imported commercial vaccines. The problem could be mitigated by preparation of vaccines from local virus strains related to those circulating in the endemically infected buffalo populations in the Kruger National Park (KNP). This study demonstrates the individual number of protective doses (PD) of five vaccine candidate strains after homologous virus challenge, as well as the vaccines safety and onset of humoral immunity in naïve cattle. Furthermore, the duration of post-vaccination immunity over a 12-month period is shown, when a multivalent vaccine prepared from the five strains is administered as a primary dose with or without booster vaccinations. The five monovalent vaccines were shown to contain a 50% PD between 4 and 32, elicit humoral immunity with antibody titers ≥2.0 log10 from day 7 post-vaccination, and cause no adverse reactions. Meanwhile, the multivalent vaccine elicited antibody titers ≥2.0 log10 and clinical protection up to 12 months when one or two booster vaccinations were administered within 6 months of the primary vaccination. An insignificant difference between the application of one or two booster vaccinations was revealed. Owing to the number of PDs, we anticipate that the multivalent vaccine could be used successfully for prophylactic and emergency vaccinations without adjustment of the antigen payloads. Furthermore, a prophylactic vaccination regimen comprising primary vaccination of naïve cattle followed by two booster vaccinations 1.5 and 6 months later could potentially maintain herd immunity over a period of 12 months.

Rotavirus diarrhoea hospitalizations among children under 5 years of age in Nigeria, 2011-2016

BACKGROUND

The high burden of rotavirus acute gastroenteritis (AGE) is well documented among children under 5 years of age, with the majority of mortality occurring in developing countries. Nigeria ranked second worldwide in the number of rotavirus deaths in 2013. As Nigeria plans to introduce rotavirus vaccine soon, a pre-vaccine documentation of rotavirus disease burden is necessary to determine vaccine impact.

METHODS

Routine rotavirus surveillance was conducted during 2011-2016 in 3 sentinel sites in Nigeria using the standard WHO protocol. Children under 5 years of age hospitalized for acute gastroenteritis were enrolled and demographic, clinical and outcome data were collected. A stool sample was subsequently obtained and tested for human rotavirus antigen using the Enzyme-linked immunosorbent assay (ELISA).

RESULTS

2694 children with acute gastroenteritis were enrolled during January 2011 to December 2016; of these, 1242 (46%) tested positive for rotavirus. Among the rotavirus positive cases, 66% and 94% were younger than 12 months and 24 months respectively. Marked peaks in rotavirus positivity were seen in January of each year. Vomiting, and use of oral and intravenous fluids occurred more often in rotavirus positive cases as compared to rotavirus negative cases.

CONCLUSION

The high prevalence of rotavirus disease highlights the need for urgent introduction of rotavirus vaccine in Nigeria. Additionally, this study provides pre-vaccine introduction disease-burden data that will serve as a baseline for rotavirus vaccine impact-assessment once vaccine has been introduced in the national immunization program.

Impact of rotavirus vaccine on all-cause diarrhea and rotavirus hospitalizations in Madagascar

BACKGROUND

Rotavirus vaccine was introduced into the Extended Program on Immunization in Madagascar in May 2014. We analyzed trends in prevalence of all cause diarrhea and rotavirus hospitalization in children <5years of age before and after vaccine introduction and assessed trend of circulating rotavirus genotypes at Centre Hospitalier Universitaire Mère Enfant Tsaralalàna (CHU MET).

METHODS

From January 2010 to December 2016, we reviewed the admission logbook to observe the rate of hospitalization caused by gastroenteritis among 19619 children <5years of age admitted at the hospital. In June 2013-December 2016, active rotavirus surveillance was also conducted at CHUMET with support from WHO. Rotavirus antigen was detected by EIA from stool specimen of children who are eligible for rotavirus gastroenteritis surveillance at sentinel site laboratory and rotavirus positive specimens were further genotyped at Regional Reference Laboratory by RT-PCR.

RESULTS

Diarrhea hospitalizations decreased after rotavirus vaccine introduction. The median proportion of annual hospitalizations due to diarrhea was 26% (range: 31-22%) before vaccine introduction; the proportion was 25% the year of vaccine introduction, 17% in 2015 and 16% in 2016. Rotavirus positivity paralleled patterns observed in diarrhea. Before vaccine introduction, 56% of stool specimens tested positive for rotavirus; the percent positive was 13% in 2015, 12% in 2016. Diverse genotypes were detected in the pre-vaccine period; the most common were G3P[8] (n=53; 66%), G2P[4] (n=12; 15%), and G1P[8] (n=11; 14%). 6 distinct genotypes were found in 2015; the most common genotype was G2P[4] (n=10; 67%), the remaining, 5, G12[P8], G3[P8], G1G3[P4], G3G12[P4][P8] and G1G3[NT] had one positive specimen each.

CONCLUSIONS

Following rotavirus vaccine introduction all-cause diarrhea and rotavirus-specific hospitalizations declined dramatically. The most common genotypes detected in the pre-vaccine period were G3P[8] and G2P[4] in 2015, the post vaccine period.

Human G9P[8] rotavirus strains circulating in Cameroon, 1999-2000: Genetic relationships with other G9 strains and detection of a new G9 subtype

Group A rotaviruses (RV-A) are the leading cause of viral gastroenteritis in children worldwide and genotype G9P[8] is one of the five most common genotypes detected in humans. In order to gain insight into the degree of genetic variability of G9P[8] strains circulating in Cameroon, stool samples were collected during the 1999-2000 rotavirus season in two different geographic regions in Cameroon (Southwest and Western Regions). By RT-PCR, 15 G9P[8] strains (15/89=16.8%) were identified whose genomic configurations was subsequently determined by complete or partial gene sequencing. In general, all Cameroonian G9 strains clustered into current globally-spread sublineages of the VP7 gene and displayed 86.6-100% nucleotide identity amongst themselves and 81.2-99.5% nucleotide identity with global G9 strains. The full genome classification of all Cameroonian strains was G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1 but phylogenetic analysis of each gene revealed that the strains were spread across 4 or more distinct lineages. An unusual strain, RVA/Human-wt/CMR/6788/1999/G9P[8], which shared the genomic constellation of other Cameroonian G9P[8] strains, contained a novel G9 subtype which diverged significantly (18.8% nucleotide and 19% amino acid distance) from previously described G9 strains. Nucleotide and amino acid alignments revealed that the 3' end of this gene is highly divergent from other G9 VP7 genes suggesting that it arose through extensive accumulation of point mutations. The results of this study demonstrate that diverse G9 strains circulated in Cameroon during 1999-2000.