This article {extract} was published in Communicable Diseases Intelligence Vol 34 No 3 September 2010 and may be downloaded as a full version PDF from the Table of contents page.
Results, continued
Vaccine preventable diseases
Introduction
This section summarises the national notification surveillance data for laboratory-confirmed influenza and notifiable diseases targeted by the National Immunisation Program (NIP) in 2008. These include diphtheria, Haemophilus influenzae type b (Hib) infection, measles, mumps, pertussis, invasive pneumococcal disease, poliomyelitis, rubella, tetanus and varicella zoster infections (chickenpox, shingles and unspecified). Data on hepatitis B and invasive meningococcal disease, which are also targeted by the NIP, can be found in this report under 'Bloodborne diseases' and 'Other bacterial infections' respectively. Other vaccine preventable diseases (VPDs) presented in this report include hepatitis A and Q fever under the 'Gastrointestinal diseases' and 'Zoonoses' sections respectively.
In 2008, there were 34,225 notifications of VPDs (20% of total notifications). This is 25% more than the 27,332 notifications of VPDs reported in 2007. Pertussis was the most commonly notified VPD (14,516, 42% of all VPD notifications). The number of notifications and notification rates for VPDs in Australia are shown in Tables 5 and 6.
There were no new vaccines added to the NIP in 2008. However, due to an international shortage of some Hib vaccines (monovalent Hib PedvaxHib®and Hib-hepatitis B Comvax®) those vaccines were replaced by the hexavalent DTP-IPV-HepB-Hib vaccine at 2, 4 and 6 months and another monovalent Hib vaccine (Hiberix® ) at 12 months in March 2008 in Victoria, Queensland and South Australia. For the remainder of 2008, Comvax® and PedvaxHib® were used only in Western Australia for Indigenous children and for all children in the Northern Territory.
Information on receipt of vaccines has been recorded on the NNDSS using the 'vaccination status' field (full, partial or unvaccinated), plus a field capturing number of doses. In January 2008, new more detailed fields were added to record 'vaccine type' and vaccination date for each dose. The new fields were intended to replace the old fields, with a transition period allowing either type of vaccination details. In 2008, 2 jurisdictions commenced using the new fields (Northern Territory and Queensland), while the remaining jurisdictions continued using the old fields. In this report data on receipt of vaccines are presented for each disease combining data from the 2 different formats.
Diphtheria
There were no notifications of diphtheria reported to the NNDSS in 2008. The last notification of diphtheria reported in Australia was a case of cutaneous diphtheria in 2001, the only notification reported since 1992.
Haemophilus influenzae type b disease
There were 25 notifications of Hib disease in 2008 corresponding to a rate of 0.1 notifications per 100,000 population. There were eight more notifications than reported in 2007. Thirty-six per cent (9/25) of notifications were amongst children aged less than 10 years, with the remainder being distributed between those aged between 30 and 84 years. Sixty per cent (15/25) of the notifications were in males with a male to female ratio of 1.5:1, unlike in 2007 when the ratio was 0.9:1 (Figure 35).
Figure 35: Notifications of Haemophilus influenzae type b infection, Australia, 2008, by age group and sex
Indigenous status was recorded for 24 of the 25 notifications; three were Indigenous and 21 were non-Indigenous. The Hib notification rate in 2008 was 0.6 per 100,000 in the Indigenous population and 0.1 per 100,000 in the non-Indigenous population, equating to a ratio of 6:1. Between 2003 and 2007, Hib notification rates in the Indigenous population were 6.6 to 30.3 times higher than the rates in the non-Indigenous population. However the figures vary dramatically because of the low number of notifications (Figure 36). This analysis excludes those notifications with an unreported or unknown indigenous status (6 for 2003, 4 for 2006 and one for each of the remaining years).
Figure 36: Notification rate for Haemophilus influenzae type b infection, Australia, 2003 to 2008, by indigenous status
Children under the age of 16 years were eligible for Hib vaccination in infancy in 2008, as Hib vaccines were introduced to the NIP for all children born after February 1993. Of the 9 notifications aged less than 16 years in 2008, five were vaccinated and four were unvaccinated. Of the five that were vaccinated, two had received their age appropriate vaccinations and three had not been fully vaccinated for age. Vaccination status for a total of 3 notifications across all ages was unknown or not supplied.
After nearly 2 decades of Hib vaccination, Australia now has one of the lowest rates of Hib in the world.41 A recent study on the trends of invasive Hib in Australia between 1995 and 2005 concluded that almost 60% of invasive Hib cases in children are preventable.42
Influenza
The Australian 2008 influenza season was less severe than the 2007 season, but the number of notifications was higher than in each of the years 2004 to 2006 (Figure 37). Notifications were 1.9 times greater than the 5-year mean and peaked in the first week of September. There were 9,137 notifications of laboratory-confirmed influenza in 2008, corresponding to a rate of 43 per 100,000 population. Queensland accounted for 41% of all confirmed influenza notifications to the NNDSS (Figure 38), but this proportion may in part reflect different testing and laboratory practices rather than real differences in the incidence of infection.43 Notifications in the non-seasonal period were higher than in previous years.
Figure 37: Notifications of laboratory-confirmed influenza, Australia, 2008, by month of diagnosis
Figure 38: Notifications of laboratory-confirmed influenza, Australia, 2008, by state or territory and week of diagnosis
The highest notification rates occurred in the Northern Territory with 91 per 100,000 population, followed by Queensland (86 per 100,000 population), Tasmania (78 per 100,000 population) and the Australian Capital Territory (71 per 100,000 population) (Table 5).
There were 1,351 notifications of laboratory-confirmed influenza in children aged less than 5 years (14.8% of all notifications). As in previous years, influenza notification rates were markedly higher in children aged under 5 years (98 per 100,000 population) compared with those aged 5 years or over (39 per 100,000 population) (Figure 39). Within this age group, the highest rate was in children under 1 year of age (162 per 100,000 population).
Figure 39: Notification rate for laboratory-confirmed influenza, Australia, 2008, by age group and sex*
* Excludes 14 notifications whose age or sex was not reported.
In 2008, 8,906 (98.5%) influenza notifications in the NNDSS included typing data. Influenza B was predominant in the 2008 season; the first year this has been observed since influenza became nationally notifiable in 2001. Of typed notifications, 55% (4,924) were influenza B, 44% (3,894) were influenza A and 1% of notifications were notified as 'A&B' (86) or type C (2). Prior to the start of the season, influenza notifications were predominantly influenza A, however influenza B predominated during the peak of the season (Figure 40).
Figure 40: Notifications of laboratory-confirmed influenza, Australia, 2008, by type and week of diagnosis*
* Notifications of influenza type 'A&B' (n = 86), 'C' (n = 2) and 'untyped' (n = 231) were excluded from analysis.
In 2008, 1,224 influenza virus isolates were analysed at the WHO Collaborating Centre for Reference and Research on Influenza. There were approximately equal proportions of viruses from the 2 influenza B lineages (B/Victoria and B/Yamagata), however B/Yamagata viruses (B/Florida/4/2006-like included in the 2008 influenza vaccine) were predominant at the start of the season, while B/Victoria (B/Malaysia/2506/2004-like) viruses predominated at the end of the season. Of circulating A(H3) viruses, most were antigenically similar to A/Brisbane/10/2007; the 2008 A(H3) vaccine strain. Circulating A(H1) strains showed significant drift away from the 2008 vaccine strain A/Solomon Islands/3/2006 to the A/Brisbane/59/2007-like viruses.
The recommendation for the 2009 Southern Hemisphere vaccine had only one change compared with the 2008 Southern Hemisphere vaccine: a change to the A(H1) virus from a A/Solomon Islands/3/2006-like virus to A/Brisbane/59/2007-like virus. The other 2 recommended strains: A/Brisbane/10/2007-like virus (H3N2) and B/Florida/4/2006-like virus, were left unchanged.
Invasive pneumococcal disease
There were 1,629 notifications of invasive pneumococcal disease (IPD) in Australia in 2008, a rate of 7.6 notifications per 100,000 population. This was a small increase of 10% from the 1,483 notifications reported in 2007 (7.0 notifications per 100,000 population). An increase in notification rates between 2007 and 2008 was seen in New South Wales (547 notifications, 7.8 per 100,000 population), South Australia (120 notifications, 7.5 per 100,000 population), Tasmania (39 notifications, 7.8 per 100,000 population), Victoria (355 notifications, 6.7 per 100,000 population) and Western Australia (162 notifications, 7.5 per population). The lowest notification rate in 2008 was seen in the Australian Capital Territory (20 notifications, 5.8 per 100,000 population).
In 2008, males accounted for 913 (56%) of the 1,629 notifications of IPD. In most age groups there were more male than female notifications, resulting in a male to female ratio of 1.3:1. Figure 41 shows that the highest rates of IPD in 2008 were notified in persons aged 85 years or over (36.1 notifications per 100,000 population) and in children aged 1 year (32.9 notifications per 100,000 population).
Figure 41: Notification rate for invasive pneumococcal disease, Australia, 2008, by age group and sex
The 7 valent pneumococcal conjugate vaccine (7vPCV) became available for infants and children at high risk of IPD in 2001. In 2005 it was added to the NIP for all children up to 2 years of age.11 Notification rates of IPD disease caused by 7vPCV serotypes in the Indigenous population have declined over the past 5 years, from 7.8 to 3.2 notifications per 100,000 population (38 to 17 notifications) between 2003 and 2008. In the non-Indigenous population, notification rates of 7vPCV serotype disease have also declined from 5.8 to 1.2 notifications per 100,000 population (1,132 to 235 notifications) between 2004 and 2008.
The 23 valent pneumococcal polysaccharide vaccine (23vPPV) has been on the NIP since 1999 for all Indigenous Australians over 50 years of age and for those 15 to 49 years of age with high risk conditions. Since 2005, 23vPPV has also been on the NIP for all Australians over the age of 65 years. The number of notifications of IPD in both Indigenous and non-Indigenous populations due to 23vPPV serotypes increased between 2003 and 2008 from 61 to 86 notifications (12.6 to 15.9 notifications per 100,000 population) and 184 to 658 notifications (0.9 to 3.1 notifications per 100,000 population) respectively (Figure 42).
Figure 42: Notification rate for invasive pneumococcal disease, Australia, 2003 to 2008, by serotype
Additional data were collected on notifications of IPD in all Australian jurisdictions during 2008. Details can be found in the invasive pneumococcal disease annual report series published in CDI, at www.health.gov.au/cdi
Measles
There were 65 notifications of measles reported to NNDSS in 2008 corresponding to a rate of 0.3 notifications per 100,000 population. This was a large increase compared with the 12 notifications reported in 2007 (0.1 per 100,000 population) (Figure 43). In 2008, notifications were reported from New South Wales (39), Queensland (11), Western Australia (8), Northern Territory (3), Victoria (2), and South Australia (2).
Figure 43: Measles notifications, Australia, 2003 to 2008, by month of diagnosis
In 2008, 55% (36/65) of measles notifications were male. The age at diagnosis ranged from 7 months to 48 years with the median age being 17 years. There was an increase in notifications in all age groups compared with 2007. This increase was highest in those 25–34 years of age (19 in 2008 compared with 0 in 2007) (Figure 44).
Figure 44: Trends in measles notifications, Australia, 2003 to 2008, by age group
Of the 54 notifications with information on the place of acquisition, 26% (14/54) were reported as being acquired from overseas including the United Kingdom, Dubai, Thailand, Japan, China and India. There were 2 outbreaks with more than 5 cases during 2008: one with 9 cases in Western Sydney associated with an emergency department and another in Queensland with 8 cases where the source of infection was not identified.
Two doses of MMR are funded for children and provided at 12 months and 4 years of age under the NIP. The MMR vaccine induces long-term measles immunity in 95% of recipients after a single dose and 99% of recipients after the second dose.11
Nationally, there was information on vaccination status for 86% (56/65) of notifications in 2008, of which 61% (34/56) were not vaccinated and 39% (22/56) had been vaccinated (7 with 2 doses, 10 with 1 dose of a measles-containing vaccine and the remaining 5 with no dose stated) (Figure 45). The 5 non-vaccinated infants aged less than 1 year of age at diagnosis were ineligible for routine vaccination. None of the 7 notifications for children aged 1–3 years and eligible for 1 dose of the measles-mumps-rubella vaccine (MMR) were vaccinated.
Figure 45: Notifications for measles, Australia, 2008, by age group and vaccination status
For the 29 notifications aged 4–25 years and eligible for 2 doses of MMR (with vaccine information available), 48% (14/29) were not vaccinated and 52% (15/29) had been vaccinated, seven of which had 2 doses and five of which had 1 dose of a measles-containing vaccine.
There were 13 notifications with information on vaccination status in those aged 26–40 years. These are considered to be a susceptible age cohort because many may have missed being vaccinated as infants when coverage was still low and the risk of natural immunity through exposure was declining. Of these, 46% (6/13) were not vaccinated and 54% (7/13) were vaccinated, five of these with 1 dose and two had no dose number stated.
The remaining 2 notifications with vaccine information provided were both 41 years or older and not vaccinated.
Mumps
In 2008, there were 286 notifications of mumps (1.3 per 100,000 population). This was approximately half of the 586 notifications of mumps (2.8 per 100,000 population) reported in 2007. In 2008, notifications were similar to the 5-year mean, with a ratio of 1.1.
Notifications were reported from all jurisdictions except the Australian Capital Territory. The majority were reported from Western Australia with 33% (95/286), followed by 27% (77/286) from New South Wales and 18% (53/286) from the Northern Territory (Figure 46). The highest mumps notification rate was in the Northern Territory with 24 notifications per 100,000 population. Western Australia had the second highest notification rate in 2008 with 4.4 notifications per 100,000 population. New South Wales experienced the largest decrease in mumps notification rates from 2007 (4.7 per 100,000 population, 323 notifications) to 2008 (1.1 per 100,000 population, 77 notifications).
Figure 46: Notifications of mumps, Australia, 2003 to 2008, by state or territory and month of diagnosis
While the crude annual national mumps notification rate in Australia has been increasing since 2004, the rate in 2008 was the same as for 2006 (1.3 per 100,000 population) and close to that for 2005 (1.2 per 100,000 population), with rates in the less than 5 years and the 35 years or over age groups remaining relatively constant over the last 5 years (Figure 47).
Figure 47: Trends in notification rates for mumps, Australia, 2003 to 2008, by age group
In 2008, there were notifications of mumps in all age groups with the highest notification rates amongst adolescents and young adults. Rates in children aged less than 5 years (1.09 per 100,000 population, or 15 notifications) and adults greater than 40 years of age remained low (Figure 48). A decrease in the notification rates for both the 15–24 and 25–34 year age groups in 2008 compared with 2007 was apparent (Figure 47). In 2008, the highest notification rates for males were in the 10–14 and 15–19 year age groups (Figure 48), compared with 2007 where the highest rates occurred in the 25–29 year age group. The majority of notifications (55%, 156/286) were male, a similar proportion to the past 5 years.
Figure 48: Notification rate for mumps, Australia, 2008, by age group
Nationally, information on vaccination status was available for 85% (242/286) of the notifications of which 39% (94/242) were not vaccinated, 36% (89/242) were vaccinated, and the remaining 24% (59/242) were reported as not applicable or unknown. Of the vaccinated notifications 2% (2/89) had 3 doses, the majority 68% (62/89) had 2 doses and 22% (20/89) had 1 dose of a mumps-containing vaccine, and the remaining five had missing or unknown dosage information.
Of the 69 Indigenous notifications with a known vaccination status, 96% (66/69), were vaccinated; of which 3% (2/66) had received 3 doses, 82% (54/66) had 2 doses and 15% (10/66) had 1 dose of a mumps-containing vaccine. Only 4% (3/69) of Indigenous notifications in 2008 were not vaccinated.
Indigenous status was reported for 77% (220/286) of mumps notifications, of which 50% (110/220) were reported as Indigenous and 50% as non-Indigenous. This represents a 15.5% increase in the proportion of Indigenous notifications in 2008 compared with the 23% (135/586) reported in 2007.
Of the cases notified from Western Australia and Northern Territory in 2008, 69% (66/95) and 75% (40/53) respectively were identified as Indigenous. In 2008, Western Australia experienced the end of a prolonged mumps outbreak in the Kimberly region that began in July 2007 and had peaked by the end of 2007.28 The outbreak occurred predominantly amongst adolescent and young adult Aboriginal people (median age 18 years)44 and had epidemiological links to an outbreak in Indigenous communities in the Northern Territory (personal communication, Gary Dowse, Communicable Disease Control, Directorate, Western Australian Department of Health). The affected population had a high rate of vaccination, with 52% (80/153) having received 2 doses and 14% (22/153) having received at least 1 dose of mumps containing-vaccine. Genotype J was identified in 20 mumps isolates and it remains unclear whether the outbreak was linked to the introduction of new genotypes from overseas outbreaks.44
The mumps component of the MMR vaccine is the least effective of the 3 components, providing 62%–85% and 85%–88% protection for the first and second dose respectively, compared with 95% for measles and 98% for rubella. Reduced effectiveness of the mumps vaccine component over time has been demonstrated to wane for 1 dose from 96% in 2-year-olds to 66% in 11–12-year-olds; and for 2 doses to wane from 99% in 5–6-year-olds to 86% in 11–12-year-olds.45 This may at least partially account for the proportion of vaccinated mumps cases. Reduced efficacy has been suspected as a factor in recent mumps outbreaks in Israel and the United States of America in 2009 and 2010. Public health officials in New York are trialling a 3rd dose of vaccine in students in certain schools in Orange County as mumps transmission has continued despite a high rate of 2-dose vaccination coverage.45,46
Pertussis
Pertussis is the most common vaccine preventable illness in Australia, with periodic epidemics occurring at intervals of three to 5 years on a background of endemic circulation. Notifications are normally higher in late winter and spring, however from 2004 to 2006, non-seasonal activity remained elevated compared with previous years (Figure 49). This may have been partially due to errors in diagnosis as discussed in the 2007 NNDSS annual report.28
Figure 49: Notifications of pertussis, Australia, 2003 to 2008, by month of diagnosis
In 2008, 14,516 notifications of pertussis were reported to NNDSS representing a notification rate of 67.7 per 100,000 population and was higher than in 2007 (5,345; 25.4 per 100,000 population). There was a large increase in the number of notifications from mid-2008, particularly in New South Wales, marking the beginning of an epidemic period which peaked in March 2009. In 2008, uptake of nucleic acid testing overtook serological methods for diagnosing new cases in New South Wales.
Notification rates in 2008 varied with age, with the highest notification rates in those aged less than 15 years (114.2 per 100,000 population). This contrasted with 2006 where those aged 20–59 years and 60 years or over had the highest notification rate (Figure 50). Rates in these older age groups increased between 2003 and 2006, however by 2007 rates in these age groups had decreased. These older age groups were seen to have increasing rates since 2003, however by 2007 their notification rates had returned to a lower level. The notification rates of all groups less than 15 years increased more rapidly between 2007 and 2008 than those aged greater than 15 years.
Figure 50: Trends in the notification rates of pertussis, Australia, 2003 to 2008, by age group
There were more notifications amongst females (8,167; 56.3%) than males (6,333; 43.7%) in 2008, with 16 notifications for which sex was not specified (Figure 51). The highest notification rate amongst females was in the 0–4 year age group (126.9 per 100,000 population) with the highest rate in males being in the 10–14 year age group (122.5 per 100,000 population). While the greatest notification rates in 2008 were in those aged less than 15 years, the pattern of predominance of female notification rates compared with male notification rates for all age groups was similar to 2007 except for those aged 10 years, 70–74 years and those aged 85 years or over.
Figure 51: Notification rate for pertussis, Australia, 2008, by age and sex
Nationally, information on vaccination was available for 71% (10,257/14,516) of notifications of which 65% (6,670/10,257) were not vaccinated and 35% (3,587/10,257) were vaccinated. No data were entered or vaccination status was unknown for 29% (4,259/14,516) of notifications. Information on the number of vaccine doses was less than 35% complete, thereby restricting further analysis of this field.
The newer nationally agreed vaccine type field used by Queensland and the Northern Territory was complete or status known for 91% (2,478/2,737) of notifications of which the majority (91%; 2,264/2,478) reported no vaccine given. Of those reporting no vaccine given, 89% (2,004/2,264) were aged 15 years or more, 8% (175/2,264) were between five and 15 years and 4% (85/2,264) were aged less than 5 years. All notifications aged more than 4 years would have been eligible for at least 4 doses of pertussis containing vaccine. Thirty-nine notifications would have been eligible for 1 dose at age of diagnosis and 15 notifications were less than 8 weeks of age and thus not eligible for their 1st dose of pertussis containing vaccine. Vaccine effectiveness is estimated to be 68% after receiving 1 dose of vaccine, increasing to 92% and greater after the 2nd dose47 increasing to 99% following subsequent doses.48 Immunity to disease decreases over time post vaccination with estimates of protection remaining for 4–12 years.47 For this reason, current vaccine schedules for pertussis under the NIP are at 2, 4 and 6 months followed by a booster at aged 4 years and again at 15–17 years of age.
Notification rates of pertussis varied considerably by residential location. This was particularly noticeable in the 2nd half of 2008. By jurisdiction, the highest rates were in the Northern Territory (217.0 per 100,000 population) and New South Wales (111.9 per 100,000 population). When comparing rates by Statistical Divisions in Australia in the 1st half of 2008 with the 2nd half (Map 3), Northern Tasmania had the highest notification rate of 11.8 per 100,000 population. Loddon and the Central Highlands in Victoria had the next highest notification rates (10.0 and 8.1 respectively), and Central West New South Wales, South Eastern New South Wales and Murrumbidgee in New South Wales also demonstrated marked increases in the 2nd half compared with the 1st half of 2008 with rates of 9.3, 7.2 and 7.0 per 100,000 population respectively.
Map 3: Notification rate ratio for pertussis comparing January to June with July to December 2008, by Statistical Division of residence
* Numbers shown in the Statistical Divisions represent the count of notifications.
Notification rates in geographic areas where estimated residential population and case numbers are small should be interpreted with caution.
Poliomyelitis
In 2008 there were no notifications of poliomyelitis in Australia, which along with the Western Pacific Region (WPR), remained poliomyelitis free. Poliomyelitis is a notifiable disease in Australia with clinical and laboratory investigation conducted for cases involving patients of any age with a clinical suspicion of poliomyelitis. Australia follows the WHO protocol for poliomyelitis surveillance and focuses on investigating cases of acute flaccid paralysis (AFP) in children under 15 years of age. Since 2000, the surveillance for AFP has been co-ordinated by the Victorian Infectious Diseases Reference Laboratory (VIDRL) in collaboration with the Australian Paediatric Surveillance Unit (APSU). The WHO target for AFP surveillance in a polio non-endemic country is 1 case of AFP per 100,000 children aged less than 15 years. Between 1 January and 31 December 2008 there were 60 eligible AFP cases notified to the National Polio Reference Laboratory (NPRL) all of which were classified as non-poliomyelitis. The 2008 non-poliomyelitis AFP rate was 1.5 hence meeting the WHO AFP surveillance indicator for the fifth time since 1995. Details of the 2008 notifications are provided in the 2008 annual report of the Australian NPRL.49
During 2008, Australia finalised An Acute Flaccid Paralysis and Poliomyelitis Response Plan for Australia. The plan was endorsed by the Australian Health Protection Committee at their meeting on 4 December 2008 and is now available on the Australian Government's website at http://www.health.gov.au/internet/main/publishing.nsf/Content/polio-plan.htm
Rubella
In 2008, there were 37 notifications of rubella (0.2 per 100,000 population), a slight increase compared with the 34 notifications in 2007. Notifications were reported from New South Wales (17), Victoria (8), Western Australia (7), Queensland (4), and South Australia (1). There were small numbers of notifications reported across the age groups with no notifications for infants less than 1 year of age or for those adults between 50 and 80 years of age. The majority of notifications (29; 78%) were adults between 20 and 49 years of age (Figure 52). The median age was 32 years. The overall male to female ratio of notifications in 2008 was 1.1:1, with 19 males and 18 females. Of the 18 notifications that were female 15 (83%) were notified in women of child bearing age (17–47 years). Despite this, there were no notifications of congenital rubella reported in 2008.
Figure 52: Notifications of rubella, Australia, 2008, by age group and sex
Figure 53 shows that trends in rubella notifications in different age groups have continued at low levels since 2003, except for a spike amongst those aged 25–34 in 2006. This spike was primarily due to an increase of notifications from South Eastern and Central Sydney, New South Wales. It was concentrated in those aged 15–44 years, however there was no single identifiable source for the increase in notifications.50
Figure 53: Trends in notification rates of rubella, Australia, 2003 to 2008, by age group
In Australia, populations at risk of rubella have previously been identified as including young men who did not receive the rubella immunisation in school based programs,51 migrant women who did not receive rubella vaccines in their countries of birth,52,53 and Indigenous women from rural and remote communities in the Top End of the Northern Territory.54
Nationally, information on vaccination status was available for 59% (22/37) of rubella notifications of which the majority, (82%; 18/22), were not vaccinated and 18% (4/22) were vaccinated. The remaining 41% (15/37) were stated as either unknown or blank. Of the 12 male notifications with information on vaccination reported, 83% (10/12) were not vaccinated, all of whom were adults ranging from 21 to 80 years of age and two had received 1 dose of a rubella-containing vaccine. Of the 10 female notifications in 2008 with vaccination information reported, 80% (8/10) were not vaccinated (all except one were women of child-bearing age between 19 and 43 years) and two had received 1 dose of a rubella containing vaccine (aged 9 years and 35 years).
Two doses of MMR are funded for children and provided at 12 months and 4 years of age under the NIP. A single dose of rubella vaccine produces an antibody response in more than 95% of recipients. Vaccine-induced antibodies have been shown to persist for at least 16 years in the absence of endemic disease, providing long-term protection against clinical rubella for those who seroconvert.11
None of the rubella notifications in 2008 were identified as Indigenous, although of the 37 notifications, 12 were reported as unknown indigenous status.
Tetanus
In 2008, there were 4 notifications of tetanus, one each reported from New South Wales, Victoria, Western Australia and Queensland and were all aged greater than 70 years. Of the 4 notifications, three were female and one was male.
Varicella-zoster infections
In November 2005, the varicella zoster vaccine was added to the NIP schedule as a single dose due at 18 months (for children born on or after 1 May 2004), or as a catch-up dose at 10–13 years of age. In 2006, CDNA agreed to make varicella infections notifiable in Australian jurisdictions. Three categories of varicella infection are notifiable: chickenpox, shingles and varicella infection (unspecified).
By the end of 2008, all jurisdictions except New South Wales were sending data to NNDSS, however because varicella only became notifiable in Victoria on 21 September 2008, the reported notifications for 2008 are incomplete and may underestimate actual disease incidence.
New South Wales decided in 2006 not to make varicella infections notifiable however varicella surveillance occurs in this state through monitoring of emergency department presentations available from http://www.health.nsw.gov.au/data/diseases/chickenpox.asp
In 2008, there were 8,526 varicella notifications from the 7 notifying jurisdictions, with 21% (1,790/8,526) reported as chickenpox, 27% (2,309/8,526) as shingles and 52% (4,427/8,526) as unspecified varicella infection.
Varicella zoster infection (chickenpox)
In 2008, there were a total of 1,790 notifications of chickenpox reported from all jurisdictions except New South Wales, corresponding to a rate of 12.4 notifications per 100,000 population. The highest rates were reported from the Northern Territory (52.3 per 100,000 population; 115 notifications) and South Australia (38.7 per 100,000 population; 620 notifications).
A total of 1,203 notifications (67.2 %) occurred in children aged less than 10 years. The highest rates were in the 5–9 year age group (62.2 per 100,000 population; 651 notifications) (Figure 54).
Figure 54: Notification rate for chickenpox, Australia,* 2008, by age group and sex
* Excluding New South Wales.
Indigenous status was recorded for 87% (1,554/1,790) of notifications, the majority (91%; 1,418/1,554) of which were non-Indigenous.
Of the 1,790 notifications for chickenpox, information on vaccination was available for 30% (543/1,790), 80% (432/543) of these were unvaccinated.
Varicella zoster infection (shingles)
There were 2,309 notifications of shingles reported to NNDSS in 2008 from 7 jurisdictions, corresponding to a rate of 16 notifications per 100,000 population. The highest rates were in South Australia (58.1 per 100,000 population, 931 notifications) and the Northern Territory (48.2 per 100,000 population, 106 notifications).
There were more female notifications (852; 55.1%) than males (695; 44.9%). The highest rates were in the 80–84 year age group (43.7 per 100,000 population; 121 notifications. (Figure 55).
Figure 55: Notification rate for shingles, Australia,* 2008, by age group and sex
* Excluding New South Wales.
Indigenous status was recorded for 81% (1,881/2,309) of notifications with the majority (96%; 1,803/1,881) reported as non-Indigenous.
Varicella zoster infection (unspecified)
There were 4,427 notifications of varicella infections (unspecified) based on laboratory diagnoses from 7 jurisdictions in 2008, corresponding to a rate of 30.6 notifications per 100,000 population. The high proportion of unspecified varicella zoster virus infection compared with varicella zoster chickenpox or shingles is directly attributable to the varying capacity of jurisdictions to follow-up on laboratory notifications to determine the clinical presentation of each case. The highest rates were reported from Queensland (73.1 per 100,000 population; 3,138 notifications), Western Australia (34.7 per 100,000 population; 754 notifications) and the Australian Capital Territory (29.5 per 100,000 population; 102 notifications).
There were more notifications in females (2,477; 56%) than males (1,949; 46%). The age distribution of unspecified varicella infections is shown in Figure 56.
Figure 56: Notification rate for varicella zoster infection (unspecified), Australia,* 2008, by age group and sex
* Excluding New South Wales and Victoria.
Indigenous status was recorded for 29% (1,295/4,427) of notifications, with the majority (94%; 1,219/1,295) reported as non-Indigenous.
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Communicable Diseases Surveillance
This issue - Vol 34 No 3, September 2010
NNDSS Annual report 2008
Communicable Diseases Intelligence