Epidemiology of rotavirus in infants and protection against symptomatic illness afforded by primary infection and vaccination

Bayesian parameter inference for dynamic infectious disease modelling: rotavirus in Germany

Understanding infectious disease dynamics using epidemic models based on ordinary differential equations requires the calibration of model parameters from data. A commonly used approach in practice to simplify this task is to fix many parameters on the basis of expert or literature information. However, this not only leaves the corresponding uncertainty unexamined but often also leads to biased inference for the remaining parameters because of dependence structures inherent in any given model. In the present work, we develop a Bayesian inference framework that lessens the reliance on such external parameter quantifications by pursuing a more data-driven calibration approach. This includes a novel focus on residual autocorrelation combined with model averaging techniques in order to reduce these estimates' dependence on the underlying model structure. We applied our methods to the modelling of age-stratified weekly rotavirus incidence data in Germany from 2001 to 2008 using a complex susceptible-infectious-susceptible-type model complemented by the stochastic reporting of new cases. As a result, we found the detection rate in the eastern federal states to be more than four times higher compared with that of the western federal states (19.0% vs 4.3%), and also the infectiousness of symptomatically infected individuals was estimated to be more than 10 times higher than that of asymptomatically infected individuals (95% credibility interval: 8.1–19.6). Not only do these findings give valuable epidemiological insight into the transmission processes, we were also able to examine the considerable impact on the model-predicted transmission dynamics when fixing parameters beforehand.

A gastrointestinal rotavirus infection mouse model for immune modulation studies

BACKGROUND

Rotaviruses are the single most important cause of severe diarrhea in young children worldwide. The current study was conducted to assess whether colostrum containing rotavirus-specific antibodies (Gastrogard-R®) could protect against rotavirus infection. In addition, this illness model was used to study modulatory effects of intervention on several immune parameters after re-infection.

METHODS

BALB/c mice were treated by gavage once daily with Gastrogard-R® from the age of 4 to 10 days, and were inoculated with rhesus rotavirus (RRV) at 7 days of age. A secondary inoculation with epizootic-diarrhea infant-mouse (EDIM) virus was administered at 17 days of age. Disease symptoms were scored daily and viral shedding was measured in fecal samples during the post-inoculation periods. Rotavirus-specific IgM, IgG and IgG subclasses in serum, T cell proliferation and rotavirus-specific delayed-type hypersensitivity (DTH) responses were also measured.

RESULTS

Primary inoculation with RRV induced a mild but consistent level of diarrhea during 3-4 days post-inoculation. All mice receiving Gastrogard-R® were 100% protected against rotavirus-induced diarrhea. Mice receiving both RRV and EDIM inoculation had a lower faecal-viral load following EDIM inoculation then mice receiving EDIM alone or Gastrogard-R®. Mice receiving Gastrogard-R® however displayed an enhanced rotavirus-specific T-cell proliferation whereas rotavirus-specific antibody subtypes were not affected.

CONCLUSIONS

Preventing RRV-induced diarrhea by Gastrogard-R® early in life showed a diminished protection against EDIM re-infection, but a rotavirus-specific immune response was developed including both B cell and T cell responses. In general, this intervention model can be used for studying clinical symptoms as well as the immune responses required for protection against viral re-infection.

Incidence of intussusception among children 0-5 years of age in Thailand, 2001-2006

To provide baseline incidence data of intussusception among Thai children under 5 years old, outpatient and inpatient records from 2001 to 2006 from five hospitals were reviewed. 112 cases of intussusception were identified, confirmed by either ultrasonography (65%), radiology procedure (32%) or surgery (3%). Common presenting symptoms were vomiting, mucous bloody stool and fever. 50% of intussusceptions were ileocolic in location and 49% underwent surgery. Male to female ratio was 1.7:1 and 86% of cases were under 1 year of age. No deaths were reported. 89 of 112 cases were resident in the study catchment area, for an annual incidence of 19.70-47.83 and 4.36-11.44 per 100,000 children under 1 and 5 years of age, respectively. This is somewhat lower than other regional studies emphasising need to continue and enhance surveillance prior to starting a universal rotavirus vaccine program.

Effectiveness of childhood vaccination against rotavirus in sub-Saharan Africa: The case of Nigeria

Rotavirus diarrhoea is associated with high childhood mortality in developing countries. A new vaccine was recently licensed in Mexico. The objective of this study was to assess the effectiveness of routine childhood vaccination by this new vaccine in a developing country. We constructed a decision tree to compare two alternatives: "no vaccination programme" and "vaccination programme". The estimates used for disease incidence, vaccine efficacy and coverage rates were derived from published data. We followed a hypothetical Nigerian cohort from birth to age five. The vaccine programme would prevent 284,000 cases of rotavirus diarrhoea annually and 6129 deaths due to the disease. In this study in a sub-Saharan country, we showed that rotavirus vaccination with a new vaccine substantially reduces the number of deaths from rotavirus diarrhoea and may be of great use in developing countries.

Consumption of untreated tank rainwater and gastroenteritis among young children in South Australia

BACKGROUND

Tank rainwater is a source of untreated drinking water in Australia and elsewhere. The aim of this study was to determine whether the risk of gastroenteritis among children who drank tank rainwater differed from that of children who drank treated public mains water.

METHODS

A cohort study of 1,016 4- to 6-year old children who drank rainwater or treated mains water in rural South Australia was undertaken in 1999. Parents kept a daily diary of their child's gastrointestinal symptoms and water consumption for a period of 6 weeks. Data on respiratory illness and other risk factors for gastroenteritis were also collected.

RESULTS

The incidence of gastroenteritis among children was 3.8-5.3 episodes per child-year, but most episodes (60%) lasted just 1 day. No increase in odds of gastroenteritis was observed among children who drank rainwater compared with treated mains water. The adjusted odds ratio for gastroenteritis associated with rainwater consumption compared with mains consumption was 0.84 (95% confidence interval 0.63-1.13).

CONCLUSIONS

Gastroenteritis was found to be a significant cause of morbidity among young children. Young children, who were regular consumers of tank rainwater, were at no greater odds of gastroenteritis than those who drank treated public mains water.

[Morbidity and cost of rotavirus infections in France]

BACKGROUND

Rotavirus is the most common cause of severe diarrhea in children. Morbidity and mortality related to rotavirus infection is not well known in temperate countries in general, and in France in particular.

OBJECTIVES

The aim of this study was estimate the morbidity, mortality, and cost related to the rotavirus infection in France, in order to assess the potential impact of a vaccination program.

METHODS

A birth cohort was followed until 5 years of age using a decision tree model. Rotavirus infection incidence rates were modeled according to age, seasons, and breast-feeding status.

RESULTS

Based on estimates from a decision model, we found that in France, rotavirus infection was responsible for 300,000 annual episodes of acute diarrhea, 138,000 visits to general practitioners, 18,000 hospitalizations, and 9 deaths. The annual direct cost related to rotavirus infection care was estimated at 28 million euros.

CONCLUSION

This study demonstrates the high morbidity and cost of care associated with rotavirus infection in France. The decision tree model developed in this study could be used in the future to estimate the potential effectiveness, cost and cost-effectiveness of childhood vaccination strategies using new rotavirus vaccines.

Cross-reactivity between the major Parietaria allergen and rotavirus VP4 protein

BACKGROUND

The present study investigates immunological cross-reactivity between Par o 1, the major pollen allergen of Parietaria, and the VP4 protein of rotavirus, a microorganism that is world-wide the main etiological agent of gastroenteritis in children.

METHODS

IgG and IgE cross-reactivity was assessed by direct binding and competitive inhibition assays (ELISA and DARIA), using recombinant VP4 from rhesus infectious rotavirus (RR), synthetic peptides and Par o 1-specific antibodies affinity purified from pooled and individual human sera.

RESULTS

Antibodies specifically binding Par o 1, affinity purified from the sera of 35 individuals with skin test positivity to Parietaria and from 14 pools, were extensively cross-reactive with RRVP4. Cross-reactive binding was specifically inhibited by synthetic peptides derived from the C-terminal sequences of the VP4 proteins from human and rhesus infectious rotavirus.

CONCLUSIONS

This study reports the first evidence of cross-reactivity between an allergen and a viral antigen.

Immunogenicity and protective efficacy of a formalin-inactivated rotavirus vaccine combined with lipid adjuvants

The immunogenicity and protective efficacy of inactivated rotavirus vaccine administered intramuscularly with lipid adjuvants; MPL (monophosphoryl lipid A from Salmonella minnesota) or L3 (monooleate/lauric acid) was evaluated in an infant mouse model. Purified and formalin-inactivated rhesus rotavirus (I-RRV) combined with one of the adjuvants were administered to female balb/c mice at 0, 4 and 8 weeks. High serum IgG antibody titers developed in all vaccinated groups; I-RRV (GMT 45524+/-9819), I-RRV-MPL (GMT 190637+/-64250) and I-RRV-L3 (GMT 126266+/-27553). The formalin-inactivation procedure preserved neutralizing epitopes and elicited high neutralizing antibody titers; I-RRV (GMT 43053 S.E.M.+/-4189), I-RRV-MPL (GMT 66398 S.E.M.+/-20202) and I-RRV-L3 (GMT 60887 S.E.M.+/-10750). All offsprings to immunized dams were protected against clinical diarrhea upon oral challenge with RRV. The IgG1/IgG2a ratio was in all immunized groups approximately 1 suggesting development of a balanced Th1/Th2 response.

Viral infections of the gastrointestinal tract

Viral gastroenteritis is a major public health problem worldwide, and the number of identified pathogens continuously increases. Investigators have made considerable progress toward understanding both the epidemiology and the mechanisms of virus-cell interactions, host responses, and pathogenesis. A vaccine for the most important pathogen, rotavirus, has been approved by the US Food and Drug Administration, but possible complications have temporarily curbed the use of this vaccine.