Vaccine Preventable Diseases in Australia, 2005 to 2007

3.13 Rotavirus

Page last updated: 24 December 2010

Rotavirus is a non-enveloped virus that is the major cause of acute gastroenteritis in young children and infants. Infection can be asymptomatic, cause mild to moderate gastroenteritis, or severe gastroenteritis with dehydration requiring hospitalisation.1 Virtually all children worldwide are infected with rotavirus by 5 years of age, but severe disease occurs most commonly in those aged 6 months to 2 years.2,3 Each year >500,000 deaths occur in children <5 years of age worldwide, with >80% of deaths occurring in developing countries.4 However, disease does occur in all age groups.1 Rotaviruses are primarily spread by faecal–oral transmission. Infection with rotavirus confers protection against subsequent serious disease.5 Rotaviruses are typed based on two surface proteins, VP7 (‘G’, glycoprotein) and VP4 (‘P’, protease sensitive protein). Viruses that contain either G1, 2, 3, 4 or 9 (and either P4 or P8) are the five most common virus types currently circulating in Australia.6

Two vaccines for the prevention of rotavirus gastroenteritis became available in Australia in 2006. Both products are oral live attenuated vaccines for use in infants, in either a 2-dose course at 2 and 4 months of age (Rotarix®, a live attenuated human rotavirus), or a 3-dose course at 2, 4, and 6 months of age (RotaTeq®, a pentavalent human-bovine reassortant rotavirus). Rotavirus vaccination commenced in the Northern Territory in October 2006, and was funded for all Australian infants under the National Immunisation Program from July 2007. Rotarix® is used in the Northern Territory, the Australian Capital Territory, New South Wales and Tasmania. RotaTeq® is used in Victoria, South Australia and Queensland. Western Australia changed from using Rotarix® to RotaTeq® in May 2009. Overall, it is estimated from pre-licensure studies that vaccination prevents around 70% of rotavirus gastroenteritis of any severity and 85%–100% of cases of severe gastroenteritis in immunised infants/children.7,8

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Case definitions

Hospitalisations and deaths

The ICD-10-AM/ICD-10 code A08.0 (rotaviral enteritis) was used to identify hospitalisations and deaths.

Northern Territory notification data

Northern Territory notification data for the period January 2006 to December 2007 are included in this report. Historical notification data is published elsewhere.9 Cases notified in the Northern Territory meet the following case definition: ‘Detection of human rotavirus in stool, unless typing reveals it is rotavirus from a vaccine’.

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Secular trends

National notification data for rotavirus are not available for reporting, as rotavirus was not nationally notifiable during the reporting period of 2006–2007. (Notification data from the Northern Territory are reported in a later section of this chapter.)

In the 2-year review period (2005/2006 to 2006/2007), there were 8,602 hospitalisations for rotavirus (average annual rate of 20.9 per 100,000 population). Rotavirus was recorded as the principal diagnosis in 88% of these hospitalisations (Table 3.13.1). There were more hospitalisations recorded in the 2nd year of the review period (n=3,745 in 2005/2006, n=4,857 in 2006/2007). Overall, hospitalisation rates for this review period were higher in each age group, compared with the previous 3-year period (2002/2003–2004/2005).10 During that period, the number of hospitalisations for rotavirus gastroenteritis was greatest in 2002/2003 (n=4,071) (Appendix 6.3). These observations are consistent with known fluctuations in rotavirus disease activity between years.11 Rotavirus hospitalisations in temperate regions in Australia have a consistent seasonal pattern, with higher rates in the cooler months of the year from June to November. Data in the current review period was consistent with this observation, with a low of 44 hospitalisations in February 2006 and a peak of 1,141 hospitalisations in August 2006 (Figure 3.13.1).

Figure 3.13.1: Rotavirus hospitalisations, Australia, 1993/1994 to 2006/2007,* by month of admission

Figure 3.13.1:  Rotavirus hospitalisations, Australia, 1993/1994 to 2006/2007, by month of admission

* Hospitalisations where the date of admission was between July 1993 and June 2007.

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Table 3.13.1: Rotavirus hospitalisations and deaths, Australia, 2005 to 2007,* by age group

Age group
(years)
Hospitalisations
2 years
(July 2005–June 2007)
LOS per admission
(days)
Deaths
2 years
(2005–2006)
n () Rate§ () Median n Rate§
0–4
7,591
(6,747)
292.4
(259.9)
2.0
0
5–14
682
(623)
12.4
(11.4)
2.0
0
15–24
35
(23)
0.6
(0.4)
2.0
0
25–59
95
(60)
0.5
(0.3)
2.0
0
60+
199
(107)
2.7
(1.5)
4.0
2
0.03
All ages
8,602
(7,560)
20.9
(18.4)
2.0
2
<0.005

* Hospitalisations where the date of separation was between July 2005 and June 2007; deaths where the death was recorded between January 2005 and December 2006.

† LOS = length of stay in hospital.

‡ Principal diagnosis (hospitalisations).

§ Average annual age-specific rate per 100,000 population.

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Severe morbidity and mortality

The number of bed days and median length of stay were calculated only for those hospitalisations with a principal diagnosis of rotavirus. There were a total of 18,308 bed days recorded for rotavirus (average 9,154 per year). The median LOS was 2 days.

The AIHW National Mortality Database records indicate a total of 16 cases with the underlying cause of death due to rotavirus over the last 17 years (1990–2006). Seven of the deaths occurred in children <5 years of age, three in those aged 5–69 years, and six in adults aged ≥70 years. Only 3 deaths have been recorded since 2001. In the 2-year period of this report, only 2 deaths were reported, both in very elderly adults >90 years of age.

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Age and sex distribution

Across all age groups, slightly more males were hospitalised with rotavirus (male:female ratio 1.15:1). The vast majority of rotavirus hospitalisations occurred in those <5 years of age (n=7,591, 88%) (Table 3.13.1). The age distribution of hospitalisations in children <5 years of age can be seen in Table 3.13.2. The highest rate of hospitalisation occurred in those aged 12–23 months, closely followed by those aged 6–11 months. The median length of stay for hospitalisations with rotavirus as principal diagnosis was 2 days for all the age groups <5 years. Figure 3.13.2 shows the trends in hospitalisation rates by age over time in children <5 years of age. Hospitalisations recorded in infants <6 months of age appear to have declined since 2001/2002, from peak rates observed in 1999/2000 and 2000/2001, whereas other age groups have continued to have fluctuating but similar hospitalisation rates over 9 years.

Table 3.13.2: Rotavirus hospitalisations, Australia, 2005/2006 to 2006/2007,* by age group (<5 years)

Age group
(months)
Hospitalisations
2 years
(July 2005–June 2007)
n () Rate ()
0–5
793
(574)
301.3
(218.1)
6–11
1,385
(1,178)
526.3
(447.6)
12–23
2,808
(2,537)
542.5
(490.1)
24–35
1,541
(1,459)
299.7
(283.7)
36–47
687
(643)
133.4
(124.8)
48–59
376
(355)
72.0
(67.0)
All ages
7,591§
(6,747)§
292.4
(259.9)

* Hospitalisations where the date of separation was between July 2005 and June 2007.

† Principal diagnosis (hospitalisations).

‡ Average annual age-specific rate per 100,000 population.

§ Including 1 case of hospitalisation aged <5 years with unknown age in months.

Figure 3.13.2: Rotavirus hospitalisation rates, Australia, 1998/1999 to 2006/2007,* by age group (<5 years) and year of separation

Figure 3.13.2:  Rotavirus hospitalisation rates, Australia, 1998/1999 to 2006/2007, by age group (less than 5 years) and year of separation

* Hospitalisations where rotavirus was recorded as either a principal or any other diagnosis and the date of separation was between July 1998 and June 2007.

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Geographical distribution

Over the period 2005/2006 to 2006/2007, the Northern Territory recorded over 5 times the Australian average rate of hospitalisation for rotavirus gastroenteritis (Northern Territory rate: 101.4 per 100,000 population) (Appendix 6.3). Victoria had the lowest rate of hospitalisation (11.4 per 100,000 population), about half the Australian average. However, comparison of hospitalisation rates between jurisdictions is complicated by likely differences in testing practices for rotavirus, which may, in part, explain the differences in observed rates of hospitalisation.2,12

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Northern Territory notification data, rotavirus

A total of 846 cases were notified from January 2006 to December 2007 among residents of the Northern Territory, an average annual rate of 198.8 per 100,000 population. In 2006, there were more than twice as many notifications (n=590; annual rate 280.1 per 100,000 population) as in 2007 (n=256; annual rate 119.1 per 100,000 population). This represents a 57% decline in the notification rate in the Northern Territory in 2007 compared with 2006. The male:female ratio among notified cases was 1:1.

The rate of notification (198.8 per 100,000) for rotavirus was considerably higher than the hospitalisation rate (101.4 per 100,000). The peak age group of notified cases from the Northern Territory (6–11 months) (Figure 3.13.3) was younger than that of hospitalised cases from all of Australia.

Figure 3.13.3: Rotavirus notification rates, the Northern Territory, 2006 and 2007,* by age group (<5 years)

Figure 3.13.3:  Rotavirus notification rates, the Northern Territory, 2006 and 2007, by age group (less than 5 years)

* Notifications where the date of diagnosis was between January 2006 and December 2007.

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Comment

Prior to the national rotavirus immunisation program which commenced in July 2007, rotavirus was responsible for several thousand hospitalisations with either a principal or secondary diagnosis of rotavirus in Australia annually. The primary disease burden is in those <5 years of age, with hospitalisations most common in the first 2 years of life.

In addition to the caveats required in the interpretation of hospitalisation data, the use of the specific rotavirus code (A08.0) for quantifying rotavirus hospitalisations has substantial limitations. Although hospitalised patients with laboratory-confirmed rotavirus infection are likely coded as rotavirus gastroenteritis, laboratory testing for rotavirus antigen in stool specimens of children hospitalised with acute gastroenteritis is not always conducted. Clinical guidelines for the management of acute uncomplicated gastroenteritis do not recommend routine stool testing for confirmation of the aetiological agent.13 Several international studies have shown that measurement of rotavirus hospitalisation rates utilising the specific rotavirus code underestimated the true number of rotavirus-associated hospitalisations, and that the sensitivity of the rotavirus coded hospitalisations was only 25%–47%.14–16 Two Australian studies have estimated the burden of rotavirus hospitalisations, imputed from the proportion of acute gastroenteritis hospitalisations attributable to rotavirus, using distinct methodologies. Both studies, conducted a decade apart, estimated that rotavirus was responsible for approximately 10,000 hospitalisations annually in Australia, prior to vaccine introduction.12,17 In addition, the number of emergency department visits for rotavirus was estimated to be approximately 21,500 annually.17 These estimations are likely to be a more accurate picture of the true disease burden.

Compared with other developed countries, prior to the rotavirus immunisation program, Australia had a relatively high rate of hospitalisation, with an estimated 1 in 27 children hospitalised by 5 years of age.12 In Europe it was estimated that 1 in 50 children had been hospitalised by the age of 5 years, although estimates varied by country and study methods.18 Although there are limited data on nosocomial rotavirus infections in Australia, it is recognised as a significant problem in paediatric wards and hospitals, with at least 14%–19% of all rotavirus infections being hospital acquired.19,20

Rotavirus hospitalisation rates were higher in this review period in comparison with those reported for all age groups in the previous 3 years. This may reflect a greater awareness of rotavirus disease and possible increased testing or coding associated with the imminent availability of two new rotavirus vaccines. In addition, rotavirus has increasingly been recognised as a cause of morbidity in elderly patients, including in settings such as aged care facilities.21,22 Of note, the 2 rotavirus deaths recorded in this review period were in persons >90 years of age. Alternatively, higher hospitalisation rates may reflect the natural seasonal fluctuations seen in the severity of rotavirus disease.

The Australian Rotavirus Surveillance Program was initiated in June 1999 to monitor changes in the distribution of rotavirus serotypes over time. Serotype G1 continues to be the most frequently reported serotype worldwide and has been the most common Australian serotype for all but 2 years since 1999.23,24 From July 2001 to June 2003, serotype G1 was replaced by G9 as the most dominant serotype,25,26 followed by a decline in G9 prevalence in subsequent years.6,23,26,27 It appears likely that both rotavirus vaccines are effective against the G9 serotype, as well as the majority of other serotypes detected in Australia.7,8

Hospitalisation and notification data from the Northern Territory emphasise the higher burden of disease in the region, particularly in Indigenous infants and children. Historically, the Northern Territory has experienced epidemics of rotavirus on the background of endemic disease.9 These epidemics are thought to result from the relative isolation of remote communities with a lack of immunity against circulating strains, which then see a rapid spread of infection upon reintroduction of the virus.9,28,29 Rotavirus immunisation of all infants in the Northern Territory began in October 2006, 8 months earlier than the national program. The 57% decline in rotavirus notifications observed in the Northern Territory in 2007, compared with 2006, may be an early impact of vaccination in that jurisdiction, although substantial year-to-year variation in incidence has been observed prior to vaccine introduction.29 Confirmation of this trend through ongoing observations will be required.

Acknowledgement: Dr Peter Markey, Centre for Disease Control, Northern Territory Department of Health and Families, for provision of the Northern Territory rotavirus notification data.

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References

1. Clark HF, Offit PA, Parashar UD, Ward RL. Rotavirus vaccines. In: Plotkin SA, Orenstein WA, Offit PA, eds. Vaccines. 5th edn. Philadelphia: Saunders Elsevier, 2008.

2. Newall AT, MacIntyre R, Wang H, Hull B, Macartney K. Burden of severe rotavirus disease in Australia. J Paediatr Child Health 2006;42(9):521–527.

3. Parashar UD, Alexander JP, Glass RI. Prevention of rotavirus gastroenteritis among infants and children. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55(RR–12):1–13.

4. Parashar UD, Gibson CJ, Bresse JS, Glass RI. Rotavirus and severe childhood diarrhea. Emerg Infect Dis 2006;12(2):304–306.

5. Velázquez FR, Matson DO, Calva JJ, Guerrero L, Morrow AL, Carter-Campbell S, et al. Rotavirus infection in infants as protection against subsequent infections. N Engl J Med 1996;335(14):1022–1028.

6. Kirkwood CD, Bogdanovic-Sakran N, Cannan D, Bishop RF, Barnes GL. National Rotavirus Surveillance Program annual report, 2004–05. Commun Dis Intell 2006;30(1):133–136.

7. Vesikari T, Matson DO, Dennehy P, Van Damme P, Santosham M, Rodriguez Z, et al. Safety and efficacy of a pentavalent human-bovine (WC3) reassortant rotavirus vaccine. N Engl J Med 2006;354(1):23–33.

8. Ruiz-Palacios GM, Pérez-Schael I, Velázquez FR, Abate H, Breuer T, Costa Clemens S, et al. Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis. N Engl J Med 2006;354(1):11–22.

9. Armstrong P. Rotaviral gastroenteritis in the NT: a description of the epidemiology 1995–2001 and future directions for research. The Northern Territory Disease Control Bulletin 2001;8(3):1–5.

10. Brotherton J, Wang H, Schaffer A, Quinn H, Menzies R, Hull B, et al. Vaccine Preventable Diseases and Vaccination Coverage in Australia, 2003 to 2005. Commun Dis Intell 2007;31(Suppl):S1–S152.

11. Blumer C, Roche P, Kirkwood C, Bishop R, Barnes G. Surveillance of viral pathogens in Australia: rotavirus. Commun Dis Intell 2003;27(4):496–503.

12. Carlin JB, Chondros P, Masendycz P, Bugg H, Bishop RF, Barnes GL. Rotavirus infection and rates of hospitalisation for acute gastroenteritis in young children in Australia, 1993–1996. Med J Aust 1998;169(5):252–256.

13. NSW Department of Health. Acute management of young children and infants with gastroenteritis: clinical practice guidelines. Sydney: NSW Department of Health, 2002. Available from: http://www.health.nsw.gov.au/policies/PD/2005/pdf/PD2005_238.pdf Accessed on 18 May 2009.

14. Riordan FA, Quigley T. Estimating hospital admissions due to rotavirus gastroenteritis from hospital episode statistics. J Infect 2004;49(1):13–16.

15. Hsu VP, Staat MA, Roberts N, Thieman C, Bernstein DI, Bresee J, et al. Use of active surveillance to validate International Classification of Diseases code estimates of rotavirus hospitalizations in children. Pediatrics 2005;115(1):78–82.

16. Fischer TK, Viboud C, Parashar U, Malek M, Steiner C, Glass R, et al. Hospitalizations and deaths from diarrhea and rotavirus among children <5 years of age in the United States, 1993–2003. J Infect Dis 2007;195(8):1117–1125.

17. Galati JC, Harsley S, Richmond P, Carlin JB. The burden of rotavirus-related illness among young children on the Australian health care system. Aust N Z J Public Health 2006;30(5):416–421.

18. Soriano-Gabarró M, Mrukowicz J, Vesikari T, Verstraeten T. Burden of rotavirus disease in European Union countries. Pediatr Infect Dis J 2006;25(1 Suppl):S7–S11.

19. Ringenbergs ML, Davidson GP, Spence J, Morris S. Prospective study of nosocomial rotavirus infection in a paediatric hospital. Aust Paediatr J 1989;25(3):156–160.

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20. Snelling T, Cripps T, Macartney K, Dalton D, Kesson A, Isaacs D. Nosocomial rotavirus infection in an Australian children’s hospital [letter]. J Paediatr Child Health 2007;43(4):327.

21. Anderson EJ, Weber SG. Rotavirus infection in adults. Lancet Infect Dis 2004;4(2):91–99.

22. Marshall J, Botes J, Gorrie G, Boardman C, Gregory J, Griffith J, et al. Rotavirus detection and characterisation in outbreaks of gastroenteritis in aged-care facilities. J Clin Virol 2003;28(3):331–340.

23. Ward KA, McIntyre PB, Kirkwood CD, Roche PW, Ferson MJ, Van Buynder PG, et al. Rotavirus surveillance in Australia. Commun Dis Intell 2008;32(1):82–87.

24. Kirkwood CD, Cannan D, Bogdanovic-Sakran N, Bishop RF, Barnes GL, National Rotavirus Surveillance Group. National Rotavirus Surveillance Program annual report, 2005–06. Commun Dis Intell 2006;30(4):434–438.

25. Kirkwood C, Bogdanovic-Sakran N, Clark R, Masendycz P, Bishop R, Barnes G. Report of the Australian Rotavirus Surveillance Program, 2001/2002. Commun Dis Intell 2002;26(4):537–540.

26. Kirkwood CD, Bogdanovic-Sakran N, Clark R, Bishop RF, Barnes GL. Report of the Australian Rotavirus Surveillance Program 2002–03. Commun Dis Intell 2003;27(4):492–495.

27. Kirkwood C, Bogdanovic-Sakran N, Ruth B, Barnes G. Report of the Australian Rotavirus Surveillance Program 2003–2004. Commun Dis Intell 2004;28(4):481–485.

28. Kirkwood C, Bogdanovic-Sakran N, Barnes G, Bishop R. Rotavirus serotype G9P[8] and acute gastroenteritis outbreak in children, Northern Australia. Emerg Infect Dis 2004;10(9):1593–1600.

29. Schultz R. Rotavirus gastroenteritis in the Northern Territory, 1995–2004. Med J Aust 2006;185(7):354–356.

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