Natural rotavirus infection is not associated to intussusception in Mexican children

Associations of Intussusception With Adenovirus, Rotavirus, and Other Pathogens: A Review of the Literature

BACKGROUND

Intussusception is the leading cause of acute intestinal obstruction in infants. Intussusception is mostly idiopathic, but infectious pathogens are sometimes implicated. In addition, live oral rotavirus vaccines have been associated with intussusception.

METHODS

We searched the literature published between January 1, 1990, and March 16, 2020, to describe the association between intussusception among infants and young children and various pathogens, particularly adenovirus and wild rotavirus. We tallied the number of evaluations reporting a statistically significant positive association, no association and a protective association by pathogen, using any statistical method. We also calculated the median reported odds ratios (OR) of intussusception with adenovirus and rotavirus.

RESULTS

We identified 3793 records on intussusception from the literature; 17 evaluations from 15 countries that evaluated 52 pathogens were included in the analysis. All 14 evaluations of adenovirus reported a statistically significant positive association with intussusception; the median OR from 9 evaluations was 3.7 (interquartile range, 3.3, 8.2). Nine of 12 evaluations assessing rotavirus found no statistically significant association, 1 found a positive association and 2 reported a protective effect; the median OR from 12 evaluations was 0.9 (interquartile range, 0.2, 1.8). No consistent relationship was observed between any other pathogens and intussusception.

CONCLUSIONS

We documented a consistent association of intussusception with adenovirus, but no relationship between wild-type rotavirus and intussusception. Future research should focus on better understanding the mechanisms of intussusception with infectious pathogens, including following a rotavirus vaccination.

Retrospective multicenter matched case-control study on the risk factors for intussusception in infants less than 1 year of age with a special focus on rotavirus vaccines - the German Intussusception Study

Studies associate rotavirus vaccination with intussusception. In Germany, a retrospective multicenter matched case-control study was performed to identify risk factors for intussusception with a special focus on rotavirus vaccines. Children with place of birth and residence in Germany who had been treated for intussusception from 2010 to 2014 and who had been less than 1 year old at the time of intussusception were recruited. Case report forms were independently validated by two pediatricians according to the criteria of intussusception defined by the Brighton Collaboration (BC). Cases with the highest diagnostic certainty (level 1) were matched with population-based controls by age, gender, federal state, and place of residence. Information on vaccine exposures originated from vaccination certificates. One hundred and sixteen cases were matched with 272 controls. A significantly increased adjusted odds ratio (aOR) for intussusception (5.74, 95% CI: 1.51-21.79) was detected in individuals immunized with rotavirus vaccine dose 1 prior to symptom onset as compared to non-exposed individuals. Age at the start of the rotavirus immunization series did not modify the risk of intussusception. The odds for intussusception were not increased postdose 2 and 3 as well as any dose. One further risk factor for intussusception, family history of intussusception (aOR 3.26, 95% CI 1.09 - 9.77) was identified. Breastfeeding was found to have a protective effect (aOR 0.54, 95% CI 0.33 - 0.88). Rotavirus vaccine dose 1 was associated with a 5.7-fold increased risk to develop intussusception regardless of age at immunization whereas the overall risk for intussusception in the first year of life was not increased.

Infectious Etiologies of Intussusception Among Children <2 Years Old in 4 Asian Countries

BACKGROUND

The etiology of intussusception, the leading cause of bowel obstruction in infants, is unknown in most cases. Adenovirus has been associated with intussusception and slightly increased risk of intussusception with rotavirus vaccination has been found. We conducted a case-control study among children <2 years old in Bangladesh, Nepal, Pakistan, and Vietnam to evaluate infectious etiologies of intussusception before rotavirus vaccine introduction.

METHODS

From 2015 to 2017, we enrolled 1-to-1 matched intussusception cases and hospital controls; 249 pairs were included. Stool specimens were tested for 37 infectious agents using TaqMan Array technology. We used conditional logistic regression to estimate odds ratio (OR) and 95% confidence interval (CI) of each pathogen associated with intussusception in a pooled analysis and quantitative subanalyses.

RESULTS

Adenovirus (OR, 2.67; 95% CI, 1.75-4.36) and human herpes virus 6 (OR, 3.50; 95% CI, 1.15-10.63) were detected more frequently in cases than controls. Adenovirus C detection <20 quantification cycles was associated with intussusception (OR, 18.59; 95% CI, 2.45-140.89). Wild-type rotavirus was not associated with intussusception (OR, 1.07; 95% CI, 0.52-2.22).

CONCLUSIONS

In this comprehensive evaluation, adenovirus and HHV-6 were associated with intussusception. Future research is needed to better understand mechanisms leading to intussusception, particularly after rotavirus vaccination.

A case-control study of risk factors for intussusception among infants in eastern France after the introduction of the rotavirus vaccine

OBJECTIVE

The objective of the present study was to investigate the risk factors for intussusception (IS) among infants, including vaccination against rotavirus.

METHODS

Case-control study with systematic inclusion of all infants aged <1 year with suspected IS admitted to emergency departments in the eastern region of France between 1 April 2008 and 31 March 2012. All cases classed level 1 according to the Brighton classification were matched to 4 hospital controls. Two exposure windows were examined; exposure to the first dose of rotavirus vaccine in the 7 and in the 14 days prior to the occurrence of IS.

RESULTS

A total of 115 cases were matched with 457 controls. The average vaccination coverage rate over the 4 years of study was 8.6%. Rotavirus vaccine was not found to be significantly associated with the occurrence of IS in the 7 days (odds ratio (OR) not calculated; p = 0.99) and in the 14 days after administration of one dose vaccine (OR 1.33, 95% confidence interval (CI) 0.14-12.82). Infant formula alone or combined with breastfeeding was associated with an excess risk of IS (OR 2.74, 95% CI 1.10-6.79). A history of gastroenteritis within 2 weeks prior to hospitalisation was also associated with an increased risk (OR 2.24, 95% CI 1.07-4.67).

CONCLUSION

Our study indicates that infant formula alone or combined with breastfeeding is a risk factor for IS. A small, non-significant increase in the risk of IS was observed after rotavirus vaccination, although the low vaccine coverage rate likely precluded detection of a significant increase in risk.

Incidence and risk factors for intussusception among children in northern Israel from 1992 to 2009: a retrospective study

Background

Determining the background incidence of intussusception is important in countries implementing rotavirus immunization. Rotavirus immunization was introduced into the routine infant immunization program in Israel during late 2010. Incidence and risk factors for intussusception were examined in children aged less than five years between 1992 and 2009.

Methods

Data were collected from medical records of children hospitalized due to intussusception (N = 190), and from control children (N = 295), at Carmel and Hillel Yaffe hospitals in northern Israel.

Results

The average annual incidence of intussusception in Jewish and Arab children aged less than five years was estimated at 36.1 (95% CI 17.0-76.5) vs. 23.2 per 100,000 (95% CI 9.3-57.9); for infants less than 12 months of age- 128.1 (95% CI 53.0-309.6) vs. 80.1 (95% CI 29.1-242.6) per 100,000. The risk of intussusception was higher in infants aged 3–5 months: OR 5.30 (95% CI 2.11-13.31) and 6–11 months: OR 2.53 (95% CI 1.13-5.62) when compared to infants aged less than 3 months; in those living in low vs high socioeconomic communities: OR 2.81 (95% CI 1.45-5.43), and in children with recent gastroenteritis: OR 19.90 (95% CI 2.35-168.32) vs children without recent gastroenteritis. Surgical reduction was required in 23.2%. The likelihood of surgery was significantly increased in patients presenting with bloody stool, in Arabs and those who were admitted to Hillel Yaffe Hospital.

Conclusions

The incidence of intussusception prior to universal rotavirus immunization was documented in northern Israel. Despite the lower incidence, Arab patients underwent surgery more often, suggesting delayed hospital admission of Arab as opposed to Jewish patients.

A critical time for rotavirus vaccines: a review

Universal introduction of rotavirus vaccines into childhood immunization programs is expected to substantially reduce the mortality from rotavirus gastroenteritis in developing countries (currently estimated at 702,000 annual deaths among children less than 5 years of age). In addition, it is expected to virtually eliminate hospitalizations due to rotavirus gastroenteritis in developed countries. Two rotavirus vaccines, Rotarix (GlaxoSmithKline Biologicals, Belgium) and RotaTeq (Merck & Co., USA) have recently completed Phase III clinical trials, each involving more than 60,000 children. Both vaccines appear safe with respect to intussusception, and are highly efficacious in preventing severe gastroenteritis due to rotavirus strains carrying predominantly serotype G1. The monovalent human rotavirus vaccine Rotarix, possessing serotype P1A[8],G1, is being first introduced into developing countries, whereas the pentavalent bovine-human reassortant rotavirus vaccine RotaTeq, comprising G-types G1, G2, G3, G4 and P-type P1A[8], will be initially introduced into the USA and Europe. Current disease burden estimates and economic justification will be required wherever the vaccines are introduced. Confirmation of the safety of both vaccines will require extensive postlicensure evaluation in which it will be key to assure adherence to administration of the first dose of either vaccine before 3 months of age. Assessment of the ability of each vaccine to provide protection against an increasingly diverse population of rotavirus strains will crucially depend on continuous global strain surveillance. Finally, efforts to improve existing rotavirus vaccines and to develop alternative vaccines should continue, so as to ensure that the prerotavirus vaccine era is consigned to a historical context.

Clinical features and role of viral isolates from stool samples of intussuception in children

PURPOSE

To detect major acute gastroenteritis virus (rotavirus, norovirus, astrovirus, and enteric adenovirus) and non-enteric type of adenovirus (AdV) in the stools of intussusception patients and to investigate the clinical role of detected viruses.

METHODS

From March 2012 to February 2013, major acute gastroenteritis virus and non-enteric type of AdV were isolated from stool samples that collected from 44 patients treated for intussusception in Chungnam National University Hospital. Patients were divided according to age and isolated virus.

RESULTS

Virus was detected in 28 (63%) stool specimens. The virus detection rate was significantly lower in patients aged under 12 months (p = 0.04). Twenty-two patients (78.6%) had non-enteric adenovirus, 4 (14.3%) had norovirus, 1 (3.6%) had sapovirus, and 1 (3.6%) had astrovirus. AdV subgroup C (AdV 1, 2, 5, and 6) comprised the majority with 20 cases (90.9%). A monthly increment-and-decrement pattern of intussusception was similar to that of viral detection in the stool samples. Enema reductions were successful in 39 patients and surgical manual reductions were performed in 5 patients. Virus was detected in 24 patients (61.5%) of enema reduction group and 4 patients (80.0%) of surgical manual reduction group. All of the detected viruses were non-enteric adenovirus subgroup C (AdV 1, 5, and 6) in surgical reduction patients.

CONCLUSIONS

The virus detection rate was high in the stools of intussusception patients. The pattern of seasonal intussusception occurrence rate was parallel with seasonal these viral detection rate in the stool samples. These findings suggest that viral infection plays an important role in the development of intussusception and further research is warranted.

Childhood intussusception: a literature review

Background

Postlicensure data has identified a causal link between rotavirus vaccines and intussusception in some settings. As rotavirus vaccines are introduced globally, monitoring intussusception will be crucial for ensuring safety of the vaccine programs.

Methods

To obtain updated information on background rates and clinical management of intussusception, we reviewed studies of intussusception in children <18 years of age published since 2002. We assessed the incidence of intussusception by month of life among children <1 year of age, seasonality, method of diagnosis, treatment, and case-fatality.

Findings

We identified 82 studies from North America, Asia, Europe, Oceania, Africa, Eastern Mediterranean, and Central & South America that reported a total of 44,454 intussusception events. The mean incidence of intussusception was 74 per 100,000 (range: 9–328) among children <1 year of age, with peak incidence among infants 5–7 months of age. No seasonal patterns were observed. A radiographic modality was used to diagnose intussusception in over 95% of the cases in all regions except Africa where clinical findings or surgery were used in 65% of the cases. Surgical rates were substantially higher in Africa (77%) and Central and South America (86%) compared to other regions (13–29%). Case-fatality also was higher in Africa (9%) compared to other regions (<1%). The primary limitation of this review relates to the heterogeneity in intussusception surveillance across different regions.

Conclusion

This review of the intussusception literature from the past decade provides pertinent information that should facilitate implementation of intussusception surveillance for monitoring the postlicensure safety of rotavirus vaccines.

A multi-country study of intussusception in children under 2 years of age in Latin America: analysis of prospective surveillance data

BACKGROUND

Intussusception (IS) is a form of acute intestinal obstruction that occurs mainly in infants and is usually of unknown cause. An association between IS and the first licensed rotavirus vaccine, a reassortant-tetravalent, rhesus-based rotavirus vaccine (RRV-TV), led to the withdrawal of the vaccine. New rotavirus vaccines have now been developed and extensively studied for their potential association with IS. This study aimed to describe the epidemiology and to estimate the incidence of IS in Latin American infants prior to new vaccine introduction.

METHODS

Children under 2 years of age representing potential IS cases were enrolled in 16 centers in 11 Latin American countries from January 2003 to May 2005. IS cases were classified as definite, probable, possible or suspected as stated on the Brighton Collaboration Working Group guidelines.

RESULTS

From 517 potential cases identified, 476 (92%) cases were classified as definite, 21 probable, 10 possible and 10 suspected for intussusception. Among the 476 definite IS cases, the median age at presentation was 6.4 months with 89% of cases aged <1 year. The male to female ratio was 1.5:1. The incidence of definite IS per 100,000 subject-years ranged from 1.9 in Brazil to 62.4 in Argentina for children <2 years of age, and from 3.8 in Brazil to 105.3 in Argentina for children aged <1 year. Median hospital stay was 4 days with a high prevalence of surgery as the primary treatment (65%). Most cases (88%) made a complete recovery, but 13 (3%) died. No clear seasonal pattern of IS cases emerged.

CONCLUSIONS

This study describes the epidemiology and estimates the incidence of IS in Latin American infants prior to the introduction of new rotavirus vaccines. The incidence of IS was found to vary between different countries, as observed in previous studies.

TRIAL REGISTRATION

Clinical study identifier 999910/204 (SERO-EPI-IS-204).

Towards a human rotavirus disease model

While the clinical importance of human rotavirus (RV) disease is well recognized and potent vaccines have been developed, our understanding of how human RV causes diarrhoea, vomiting and death remains unresolved. The fact that oral rehydration corrects electrolyte and water loss, indicates that enterocytes in the small intestine have a functional sodium-glucose co-transporter. Moreover, RV infection delays gastric emptying and loperamide appears to attenuate RV diarrhoea, thereby suggesting activation of the enteric nervous system. Serotonin (5-HT) receptor antagonists attenuate vomiting in young children with gastroenteritis while zinc and enkephalinase inhibitors attenuate RV-induced diarrhoea. In this review we discuss clinical symptoms, pathology, histology and treatment practices for human RV infections and compile the data into a simplified disease model.

Role of astrovirus in intussusception in Nigerian infants

Intussusception (IS) is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment. Viral infections, mostly adenovirus, enteroviruses, human herpesvirus and Epstein-Barr virus are reported in 20-50% of childhood cases of IS. Between January and July 2004, six stool specimens collected from infants 0- to 8-months old diagnosed and admitted for IS were investigated for the presence of rotavirus, astrovirus and adenovirus antigens. Astrovirus antigen was detected in three of the six stool specimens by enzyme immune assay (EIA) and confirmed in two specimens by reverse transcription-polymerase chain reaction (RT-PCR). Rotavirus, non-enteric adenovirus and astrovirus were detected by EIA, as mixed infections in a single specimen. The rotavirus strain revealed a SGI+II, mixed G1G2G8P[6] genotype and had no visible electrophoretic profile. A larger study is needed to determine the extent of involvement of astroviruses in IS in infants and the virus should be included in studies investigating the aetiology of IS.

Rotaviruses and rotavirus vaccines

BACKGROUND

Rotaviruses (RVs) are an important cause of acute gastroenteritis in infants and young children worldwide, resulting in more than 600 000 deaths per annum, mainly in developing countries. Since the 1980s, there has been intensive research on the development of RV vaccine candidates, and since 2006 two vaccines have been licensed in many countries.

SOURCES OF DATA

The scientific literature since the 1970s has been consulted, and the results of original research carried out in authors' laboratories were used.

AREAS OF AGREEMENT

There are firmly established data on virus particle structure, genome composition, gene-protein assignment, protein-function assignment (incomplete), virus classification, the mechanisms of several steps of the replication cycle (adsorption, primary transcription, virus maturation-all partial), several mechanisms of pathogenesis, aspects of the immune response, diagnosis, illness and treatment, epidemiology and vaccine development.

AREAS OF CONTROVERSY

Research on the following areas is still in full flux and in part not generally accepted: several steps of the replication cycle (mechanism of viral entry into host cells, mechanisms of packaging and reassortment of viral RNAs, morphogenesis of subviral particles in viroplasms and maturation of virus particles in the rough endoplasmic reticulum (RER) with temporary acquisition and subsequent loss of an envelope), the true correlates of protection and the long-term effectiveness of RV vaccines. GROWING RESEARCH: Recently, a system that allows carrying out reverse genetics with some of the RV genes has been established which, however, has limitations. There is intensive research ongoing, which is trying to develop better and universally applicable reverse genetics systems. There is broad research on the molecular mechanisms of the immune response and on which immunological parameter correlates best with lasting protection from severe RV disease. Research into other than live attenuated vaccines is growing.

AREAS TIMELY FOR DEVELOPING RESEARCH

The establishment of better reverse genetics systems for RVs is the most important research goal for both the understanding of the molecular biology of RVs and the development of new and safe RV vaccines. The black boxes of our knowledge on aspects of RV replication (RNA packaging, RNA replication, control of reassortment and functions of the non-structural RV proteins) are under intensive research.

Seasonality of rotavirus disease in the tropics: a systematic review and meta-analysis

BACKGROUND

To date little conclusive evidence exists on the seasonality of rotavirus incidence in the tropics. We present a systematic review and meta-analysis on the seasonal epidemiology of rotavirus in the tropics, including 26 studies reporting continuous monthly rotavirus incidence for which corresponding climatological data was available.

METHODS

Using linear regression models that account for serial correlation between months, monthly rotavirus incidence was significantly negatively correlated with temperature, rainfall and relative humidity in 65%, 55% and 60% of studies, respectively. We carried out pooled analyses using a generalized estimating equation (GEE) that accounts for correlation from between-study variation and serial correlation between months within a given study.

RESULTS

For every 1 degrees C (1.8 degrees F) increase in mean temperature, 1 cm (0.39 in.) increase in mean monthly rainfall, and 1% increase in relative humidity (22%) this analysis showed reductions in rotavirus incidence of 10% (95% CI: 6-13%), 1% (95% CI: 0-1%), and 3% (95% CI:0-5%), respectively.

CONCLUSIONS

On the basis of the evidence, we conclude that rotavirus responds to changes in climate in the tropics, with the highest number of infections found at the colder and drier times of the year.

Rotavirus fecal antigen retrieval in infantile intussusception

This study was designed to assess the plausibility of an association between natural rotavirus infection and intussusception. It was conducted on 21 infants suffering from acute gastroenteritis (GE) complicated by intussusception who were compared to another 40 age- and sex-matched infants suffering from acute GE characterized by watery nonmucoid diarrhea without surgical complications. All enrolled patients were subjected to detailed history documentation, thorough clinical examination and laboratory investigations, complete stool analysis, and detection of rotavirus antigen in stools using the ELISA technique. Plain abdominal X-ray and ultrasound were also performed. The results of this study revealed 24 positive cases for rotavirus antigen in the stools of the acute uncomplicated GE patients (60.0%), while there were only ten positive cases in the intussusception group (47.6%). No significant difference in severity was detected between the two groups studied, especially in terms of signs of dehydration and need for IV fluids (p > 0.05). Most of the rotavirus positive cases among the intussusception group presented either in February or December (p < 0.05) with no significant seasonal pattern among the acute GE group (p > 0.05). In conclusion, rotavirus antigen retrieval from stools of GE patients complicated with intussusception was not statistically different from those detected among acute uncomplicated GE. Additionally, there was no association between seasonality or severity of rotavirus positive cases in acute GE patients and those with intussusception. It is thus prudent to say that wild rotavirus infection in GE patients does not carry an extra risk for the occurrence of intussusception.

Intussusception in children in Southern Israel: disparity between 2 populations

BACKGROUND

Intussusception has been associated with 1 rotavirus vaccine. Our objective was to determine intussusception rates in children in southern Israel during a 15-year period before the introduction of new rotavirus vaccines.

METHODS

All children born at the Soroka Medical Center are hospitalized in that center, enabling population-based studies. Two populations reside in Southern Israel: the Jewish population (comparable to a Western population) and the Bedouin population (comparable to a developing population). Retrospectively, all children <5 years of age admitted with ICD-9 code for intussusception were recorded as well as their demographic and clinical data.

RESULTS

During 1990-2004, 316 patients with intussusception [241 (76%) Jewish children and 75 (24%) Bedouin children] were recorded. None died. The mean annual rates for children <5 years (per 100,000) were 49.3 +/- 17.4 and 18.9 +/- 9.6 for Jewish and Bedouin children, respectively (P < 0.001), with a significant increase in intussusception rates during the study period in Bedouin (P = 0.022), but not in Jewish children (P = 0.38). Mean annual intussusception rates per 100,000 for children <12 months were 199.6 +/- 5.2 and 66.8 +/- 44.1 for Jews and Bedouin infants, respectively (P < 0.001). In Bedouin children, a significantly higher number of cases were observed from March to May, whereas no seasonality pattern was noted in Jewish children. Negative correlation between intussusception and gastroenteritis was found in Bedouin infants during the summer months, whereas no such correlation was found in Jewish infants.

CONCLUSIONS

Pre-rotavirus vaccination intussusception rate is high especially among Jewish infants in Southern Israel. Intussusception rates increased significantly during the study period in Bedouin infants.

Immunizations, neonatal hyperbilirubinemia and animal-induced injuries

PURPOSE OF REVIEW

To report recent research findings and new recommendations on immunizations, neonatal hyperbilirubinemia, and animal-induced injuries.

RECENT FINDINGS

Vaccines against rotavirus and human papilloma virus have entered clinical use. Varicella outbreaks among previously vaccinated children have prompted the recommendation for a two-dose varicella vaccine series. Broader coverage for influenza vaccination is now recommended in the US and Canada. Diagnosis and treatment of neonatal hyperbilirubinemia uses population and hour-based norms for total serum bilirubin and assessment of risk factors. Delayed cord clamping is not apparently a risk factor for jaundice but warrants more study. Universal predischarge screening shows promise but is not yet officially recommended. New treatments for hyperbilirubinemia are being evaluated. Dogs are the chief cause of animal bites in children and the largest reservoir for rabies worldwide. In North America and Europe, cats and wild animals cause most human rabies. Postexposure prophylaxis should follow region-appropriate guidelines.

SUMMARY

New vaccines are available against rotavirus and human papilloma virus. Changes have been made to official immunization recommendations. Appropriate vaccine use can reduce the pediatric disease burden further. Hyperbilirubinemia is the subject of ongoing study, which may lead to improved diagnosis and treatment protocols and reduce the incidence of acute bilirubin encephalopathy. The best tool for rabies prevention after an animal bite is prompt postexposure prophylaxis.

Molecular epidemiology of adenovirus isolates from patients diagnosed with intussusception in Melbourne, Australia

Twenty-one intussusception (IS)-associated and 59 temporally linked adenoviral isolates from clinical infections were compared. Species C (15/21 IS- and 32/59 non-IS-associated isolates) dominated. Of these, serotype 2 (AdV-2) (7/15 IS-associated isolates) and serotype 1 (AdV-1) (16/32 non-IS-associated isolates) were the most commonly identified serotypes. DNA restriction analysis of AdV-2 isolates identified six genomic types; of these, type D2 (3/7 IS- and 8/11 non-IS-associated isolates) was the dominant type after BamHI and SmaI digestion. IS-associated isolates are similar to circulating non-IS-associated strains.

Rotavirus infection enhances lipopolysaccharide-induced intussusception in a mouse model

Unexpected reports of intussusception after vaccination with the live tetravalent rotavirus vaccine RotaShield resulted in voluntary withdrawal of the vaccine. Intussusception, a condition in which the intestine acutely invaginates upon itself, is the most common cause of intestinal obstruction in children. We report here the development of a mouse model to study rotavirus-induced intussusception. In this model, both homologous murine and heterologous simian rotavirus strains significantly enhanced the rate of lipopolysaccharide (LPS)-induced intussusception, and this enhancement was replication dependent, requiring rotavirus doses of greater than one 50% infectious dose. Rotavirus-induced intussusceptions did not have observable lymphoid lead points, despite the induction of intestinal lymphoid hyperplasia after rotavirus infection. Intussusceptions are also postulated to result from altered intestinal motility, but rotavirus infection had no effect on gastrointestinal transit. LPS-induced intussusception is associated with the induction of inflammatory mediators, and intussusception rates can be modified by inflammatory antagonists. We show that rotavirus infection significantly enhanced serum tumor necrosis factor alpha and gamma interferon cytokine levels after LPS treatment compared to uninfected mice. Together, these data suggest that rotavirus infection sensitized mice to the inflammatory effects of subsequent LPS treatment to enhance intussusception rates.

Rotavirus vaccine: early introduction in Latin America-risks and benefits

Rotavirus infection is the cause of severe gastroenteritis of young children worldwide, leading to an estimate of 600,000 deaths a year. Efforts to develop an effective and safe vaccine resulted in licensing in 1998 of a live oral vaccine (RotaShield) that was withdrawn less than 1 year later when reports of cases of intussusception were linked to its application. This led to development of new rotavirus vaccine candidates that are currently in late phase III clinical trials. One of these vaccines, GlaxoSmithKline's Rotarix, was licensed in July 2004 to be used in Mexico. This review describes the general background for rotavirus vaccine development, the different vaccine candidates that have been tested or are currently being evaluated, the association of rotavirus vaccination with the bowel blockage known as intussuception, and discusses the benefits and risks of the fast-track introduction of Rotarix in Latin America, and particularly in Mexico.

Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis

BACKGROUND

The safety and efficacy of an attenuated G1P[8] human rotavirus (HRV) vaccine were tested in a randomized, double-blind, phase 3 trial.

METHODS

We studied 63,225 healthy infants from 11 Latin American countries and Finland who received two oral doses of either the HRV vaccine (31,673 infants) or placebo (31,552 infants) at approximately two months and four months of age. Severe gastroenteritis episodes were identified by active surveillance. The severity of disease was graded with the use of the 20-point Vesikari scale. Vaccine efficacy was evaluated in a subgroup of 20,169 infants (10,159 vaccinees and 10,010 placebo recipients).

RESULTS

The efficacy of the vaccine against severe rotavirus gastroenteritis and against rotavirus-associated hospitalization was 85 percent (P<0.001 for the comparison with placebo) and reached 100 percent against more severe rotavirus gastroenteritis. Hospitalization for diarrhea of any cause was reduced by 42 percent (95 percent confidence interval, 29 to 53 percent; P<0.001). During the 31-day window after each dose, six vaccine recipients and seven placebo recipients had definite intussusception (difference in risk, -0.32 per 10,000 infants; 95 percent confidence interval, -2.91 to 2.18; P=0.78).

CONCLUSIONS

Two oral doses of the live attenuated G1P[8] HRV vaccine were highly efficacious in protecting infants against severe rotavirus gastroenteritis, significantly reduced the rate of severe gastroenteritis from any cause, and were not associated with an increased risk of intussusception. (ClinicalTrials.gov numbers, NCT00139347 and NCT00263666.)

Intussusception among young children in Europe

Intussusception, a potentially lethal condition with poorly understood etiology, is the most common cause of acute intestinal obstruction in children younger than 5 years old. In some cases, the condition has been associated with administration of the first licensed rotavirus vaccine, the reassortant rhesus-human tetravalent rotavirus vaccine (RRV-TV; RotaShield). No such association has to date been reported from large phase III safety trials with new rotavirus vaccines. As 2 new, live-attenuated oral rotavirus vaccines are currently under review for approval by the European Union regulatory authorities, a review of the clinical, etiologic and epidemiologic aspects of intussusception in Europe is urgently needed. We conducted a review of Medline literature, published from 1995 onwards on intussusception in the World Health Organization's European Region. The results are compared with data from previous reviews and other regions. The classic triad of intussusception symptoms (abdominal pain, abdominal mass, bloody stools) was present in 29-33% of patients according to the medical literature reviewed. Conservative treatment (barium, air or saline enema) was the rule (81% of cases), and few complications were observed during treatment. Treatment outcome was generally favorable, with recurrence occurring in approximately 1 in 10 patients, and only 1 death reported. Structural lead points were seen in 3% of patients; no other reliable data on the etiology of intussusception were found. The incidence of acute intussusception in young children in Europe, according to 6 heterogeneous hospital-based studies, ranged from 0.66 to 2.24 per 1000 children in inpatient departments and from 0.75 to 1.00 per 1000 children in emergency departments. Peak incidences were found in children 3-9 months of age. There are still gaps in our knowledge of intussusception with respect to its etiology and especially by which mechanisms RRV-TV might have caused it to occur. Data from regions outside Europe showed that rotavirus infection and disease are not associated with intussusception. As new rotavirus vaccines become available for use in Europe, postlicensure surveillance for intussusception is indicated and may be instrumental in further understanding the epidemiology of this condition and in further assessing the safety of future vaccines.

Low titer maternal antibodies can both enhance and suppress B cell responses to a combined live attenuated human rotavirus and VLP-ISCOM vaccine

We investigated effects of low titer (Lo) circulating MatAb on protection and immunogenicity of attenuated (Att) human rotavirus (HRV) priming and 2/6-virus-like particle (VLP)-immunostimulating complex (ISCOM) boosting (AttHRV/VLP) or VLP-ISCOM alone vaccines. LoMatAb had both enhancing and suppressing effects on B cell responses, depending on tissue, antibody isotype and vaccine. Differential effects of LoMatAb on IgA responses in different tissues suggest that LoMatAb did not suppress induction of IgA effector and memory B cells but impaired homing of these cells to secondary lymphoid or effector tissues, reducing IgA antibody secreting cells and antibodies at these sites. The AttHRV/VLP vaccine partially overcame LoMatAb suppression, conferred moderate protection against virulent HRV (as measured by reduced viral shedding and diarrhea) and represents a new candidate for rotavirus vaccines for both humans and animals.

Intussusception and rotavirus associated hospitalisation in New Zealand

AIMS

To describe the epidemiology of intussusception and its relation to rotavirus associated hospitalisation in New Zealand.

METHODS

National hospital discharge data between January 1998 and June 2003 for all children younger than 3 years of age with intussusception were reviewed. Independently, children from the same age group, admitted to eight paediatric units with rotavirus gastroenteritis between May 1998 and May 2000, were identified prospectively. Epidemiological characteristics of cases with intussusception were compared with those of hospitalised rotavirus disease.

RESULTS

During the 5.5 year study period, there were 277 cases of intussusception and no deaths. Most (72%) occurred in the first year of life (age adjusted incident rate 65 per 100,000 child-years, 95% CI 56 to 74). Risk of intussusception was less in females (risk ratio 0.58; 95% CI 0.43 to 0.78) and for Maori (risk ratio 0.52; 95% CI 0.35 to 0.77) when compared with European infants. In contrast to hospitalised rotavirus cases, intussusception peaked at a younger age and lacked seasonality.

CONCLUSIONS

This study provides national baseline data on intussusception for future rotavirus vaccine programmes in New Zealand. Wild-type rotaviruses do not appear to have a major role in triggering intussusception. Prospective surveillance systems, using standardised case definitions and nested case-control methodology, are needed to further our understanding of the aetiology and epidemiology of intussusception.