This article {extract} was published in Communicable Diseases Intelligence Vol 31 No 1 March 2007 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 data for influenza and diseases targeted by the National Immunisation Program (NIP) in 2005. These include diphtheria, Haemophilus influenzae type b infection, measles, mumps, pertussis, invasive pneumococcal disease, poliomyelitis, rubella and tetanus. Data on hepatitis B and 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 presented in this report include hepatitis A and Q fever.
Two significant changes to the NIP occurred during this reporting period. In January 2005, free universal immunisation with the 7-valent pneumococcal conjugate vaccine (7vPCV) for children in the first year of life replaced the previous targeted immunisation program and free universal 23-valent pneumococcal polysaccharide vaccine (23vPPV) immunisation for adults over 65 years replaced a previous subsidised immunisation program. In November 2005, universal childhood immunisation against varicella at 18 months was introduced, with a catch-up program for children up to 12 years of age who had not had varicella vaccine, or a history of varicella infection. Inactivated polio vaccine (IPV) replaced oral polio vaccine (OPV) in various combination vaccines in 2005.
There were 17,775 notifications of vaccine preventable diseases (VPDs) with onset dates in 2005; 14% of the total notifications to NNDSS. Pertussis was the most commonly notified VPD (11,200 or 63% of all VPD notifications). Numbers of notifications and notification rates for VPDs in Australia are shown in Tables 2 and 3.
Diphtheria
Case definition – Diphtheria Both confirmed cases and probable cases are reported. Confirmed case: Requires isolations of toxigenic Corynebacterium diphtheriae or toxigenic C. ulcerans. Probable case: Requires isolation of Corynebacterium diphtheriae or C. ulcerans (toxin production unknown) and pharyngitis/laryngitis or toxic symptoms OR clinical symptoms and epidemiological links with laboratory confirmed case. |
There were no cases of diphtheria reported in 2005. The last case of diphtheria reported in Australia was a case of cutaneous diphtheria in 2001.
Haemophilus influenzae type b disease
Case definition – Haemophilus influenzae type b Only confirmed cases are reported. Confirmed case: Requires isolation of Haemophilus influenzae type b (Hib) from a sterile site OR detection of Hib antigen in cerebrospinal fluid consistent with meningitis. |
There were 17 notifications of Hib disease in 2005, a rate of 0.1 cases per 100,000 population. This was 2 more cases than reported in 2004. Eight cases (47% of total) were in children aged less than 5 years and 2 were infants aged less than 1 year. There were 11 cases in males and 6 in females, (male:female ratio 1.8:1) (Figure 37).
Figure 37. Notifications of Haemophilus influenzae type b infection, Australia, 2005, by age group and sex
Indigenous status was recorded for 16 of the 17 cases; 3 were Indigenous and 13 were non-Indigenous. The Hib notification rate was 0.6 cases per 100,000 population in Indigenous people and 0.07 cases per 100,000 population in non-Indigenous people; a ratio of 8.6:1. Between 2001 and 2005, Hib notification rates in Indigenous people have been between 4.6 and 8.6 times the rates in non-Indigenous people except in 2002 when the Indigenous rate was 25 times that of the non-Indigenous rate (Figure 38).
Figure 38. Notification rate for Haemophilus influenzae type b infections, Australia, 2001 to 2005, by Indigenous status
Cases under the age of 15 years were eligible for Hib vaccination. Of these 9 cases, 3 were unvaccinated, 2 partially vaccinated and 4 were fully vaccinated. The 4 fully vaccinated cases were all aged less than 5 years and met the case definition for vaccine failure, having received at least 2 doses of vaccine.
Influenza
Case definition – Influenza Only confirmed cases are notified. Confirmed case: Requires isolation of influenza virus by culture OR detection of influenza virus by nucleic acid testing OR detection of influenza virus antigen from an appropriate respiratory tract specimen OR a significant increase in antibody levels, or IgG seroconversion or fourfold or greater rise in antibody titre or a single high titre antibody. |
There were 4,567 reports of laboratory-confirmed influenza in 2005, a rate of 10.5 cases cases per 100,000 population. Notifications of influenza showed a peak in August (Figure 39).
Figure 39. Notifications of laboratory-confirmed influenza, Australia, 2005, by month of onset
Children aged less than 5 years made up 22% of all notifications and had a notification rate of 80.7 cases per 100,000 population (Figure 40) Children aged less than 1 year had the highest rate (153 cases per 100,000 population). The overall male to female ratio was 1:1.
Figure 40. Notification rate of laboratory-confirmed influenza, Australia, 2005, by age group and sex
In 2005, 4,379 (96%) influenza notifications had viral serotype data. Of these, 76% (3,338) were influenza A and 24% (1,041) were influenza B.
Of 1,174 influenza virus isolates analysed at the WHO Collaborating Centre for Reference and Research on Influenza in 2005, 689 were A(H3N2), 210 were A(H1N1) strains and 275 were influenza B. The majority of A(H3N2) viruses were antigenically similar to the 2005 vaccine strain A/Wellington /1/2004, but a quarter of isolates were more closely matched to the A/California/7/2004 viruses.15
There were a number of outbreaks of influenza in 2005, including an outbreak in New South Wales in a nursing home. Outbreaks of influenza B were reported in school-age children New Zealand in 2005 which resulted in 3 deaths.16
Measles
Case definition – Measles Both confirmed cases and probable cases are notified. Confirmed case: Requires isolation of measles virus or detection of measles virus by nucleic acid testing OR detection of measles virus antigen OR IgG seroconversion or significant increase in antibody level or fourfold or greater rise in titre or detection of measles specific IgM antibody in a reference laboratory (except when vaccinated 8 days to 8 weeks prior to testing) OR clinical illness characterised by a maculopapular rash and fever and cough, coryza, conjunctivitis or koplik spots and epidemiological link to a laboratory confirmed case. Probable case: Requires detection of measles IgM antibody in other than an approved reference laboratory and clinical illness. |
There were 10 notified measles cases in 2005: 8 confirmed and 2 probable. This is the lowest annual rate for Australia since national surveillance began in 1991 (Figure 41). Five cases were reported from New South Wales, 2 from Victoria and single cases in Queensland, Tasmania and Western Australia. In 2005, there were no cases reported from the Australian Capital Territory, Northern Territory or South Australia (Tables 2 and 3).
Figure 41. Notifications of measles, Australia, 1996 to 2005, by month of onset
There was only a single case of measles in children aged less than 5 years. The remaining 9 cases were aged between 11 and 42 years. Five cases were unvaccinated and 3 (including the child aged less than 5 years) were classified as fully vaccinated for age; however data on the number of doses received was missing in 2 of these cases. The vaccination status of the other 2 cases (aged 25 and 36 years) was unknown.
Figure 42 shows trends in measles notification rates by age group. In 2005, the largest proportion of measles cases occurred in adults, which reflects the success of measles vaccination programs in children and adolescents.
Of the 10 measles cases reported in 2005, three cases were known to have acquired their infection outside Australia.
Figure 42. Trends in notification rate for measles, Australia, 1999 to 2005, by age group
Mumps
Case definition – Mumps Only confirmed cases are notified. Confirmed case: Requires isolation of mumps virus or detection of mumps virus by nucleic acid testing or IgG seroconversion or significant increase in antibodies or a significant increase in antibody level, or a fourfold or greater rise in titre to mumps virus (except where there has been recent mumps vaccination) OR detection of mumps specific IgM antibody (in the absence of recent mumps vaccination) AND a clinically compatible illness characterised by swelling of the parotid or other salivary glands lasting two days or more without other apparent cause OR a clinically compatible illness AND an epidemiological link to a laboratory confirmed case. |
In 2005, there were 241 notifications of mumps (1.2 cases per 100,000 population), which was a 2.3–fold increase on the 102 cases reported in 2004. Cases were reported from all jurisdictions except Tasmania, with the largest number of cases (111) in New South Wales.
The highest rates were in males in the 25–29 year age group (6.2 cases per 100,000 population). The rate for the 0–4 year age group (0.6 cases per 100,000 population) was the same as in 2004. Unlike 2004 when the male to female ratio was 1:1, in 2005 there was a preponderance of male cases with a male to female ratio of 1.4:1.
Trends in age group notification rates for mumps show a sharp increase in the rates in the 25–34 year ae and the 15–24 year age groups in 2005 (Figure 43).
The high rate of mumps in these age groups probably represents a susceptible cohort of individuals who have not been immunised. Mumps vaccine was made available in Australia in 1980 for use at 12–15 months of age and was combined with the measles vaccine in 1982. Therefore, no childhood doses of mumps vaccine were available to individuals in the 25–34 year age group and uptake of vaccine in older individuals from the 15–24 year age group was likely to be poor.
Eight cases were recorded as fully vaccinated; 9 as partially vaccinated; 108 as unvaccinated and there was no information on the vaccination status of the remaining 115 cases. Clusters of mumps cases were reported in 2005, one cluster of 5 cases occurred in an unvaccinated family of refugees in Queensland.
Figure 43. Trends in notification rate of mumps, Australia 2005, by age group
Pertussis
Case definition – Pertussis Both confirmed cases and probable cases are notified. Confirmed case: Requires isolation of Bordetella pertussis or detection of B. pertussis by nucleic acid testing OR seroconversion or significant increase in antibody level or fourfold or greater rise in titre (in the absence of pertussis vaccination) or a single high-titre IgA to whole cells or detection of B. pertussis by immunofluorescence AND clinical evidence (a coughing illness lasting 2 weeks or more or paroxysms of coughing or inspiratory whoop or post-tussive vomiting) OR clinical evidence AND epidemiological link to a confirmed case. Probable case: Requires clinically compatible illness. |
Pertussis continues to be the most common vaccine preventable illness in Australia, with periodic epidemics occurring at intervals of 3 to 5 years on a background of endemic circulation (Figure 44). In 2005 there were 11,200 cases notified to NNDSS (55.1 cases per 100,000 population). Of these, 10,744 were confirmed and 454 were probable, while the status of the remaining 2 cases was unknown.
Figure 44. Notifications of pertussis, Australia, 1996 to 2005, by month of onset
The highest notification rate was among children aged less than 1 year (237 cases, 92.2 cases per 100,000 population). The notification rate in persons aged 20–59 years and 60 years and over continued to increase in 2005 to 63.1 and 61.2 cases per 100,000 population, respectively (Figure 45). In 2005, 83% of pertussis cases were aged 20 years and over compared to 59% in 1999. Although severe morbidity and mortality are less likely in these age groups, they are an important pertussis reservoir, facilitating transmission to children too young to be fully vaccinated. In 2005, pertussis incidence in adolescents aged 10–19 years fell substantially from an average rate of 75.7 cases per 100,000 population between 1999–2004, to 41.5 cases per 100,000 population in 2005. School-based adolescent pertussis vaccination programs (including 2 whole of high school programs in New South Wales and Western Australia) began in a number of states in 2004, and the decrease in incidence in the targeted age group in 2005 may be the first evidence of the impact of this vaccine. Pertussis notifications were more common among women with a male to female ratio of 0.7:1.
Figure 45. Trends in notification rate of pertussis, Australia, 1999 to 2005, by age group
Notification rates of pertussis varied considerably by geographic location (Map 6).
The highest rates were reported from South Australia, New South Wales and the Australian Capital Territory. The trends in pertussis notification rates by month of diagnosis are shown for these 3 states and for Australia in Figure 46.
Map 6. Notification rate for pertussis, Australia, 2005, by Statistical Division of residence
Figure 46. Notification rate for pertussis, Australian Capital Territory, New South Wales, South Australia, and Australia, 2003 to 2005, by month of notification
Invasive pneumococcal disease
Case definition – Invasive pneumococcal disease Only confirmed cases are notified. Confirmed case: Requires isolation of Streptococcus pneumoniaefrom a normally sterile site by culture or detection by nucleic acid testing. |
There were 1,684 notifications of invasive pneumococcal disease (IPD) in Australia in 2005 giving a rate of 8.3 cases per 100,000 population. Notification rates declined in 2005 by 30% nationally with the declines in all jurisdictions of between 21% and 46%. The Northern Territory continued to have the highest notification rate (35 cases per 100,000 population) while Victoria had the lowest (6 cases per 100,000 population). The geographical distribution of IPD varied within states and territories, with the highest rates in central and northern Australia.
In 2005, rates of IPD fell in all age groups, particularly in children aged less than 5 years (20.4 cases per 100,000 population compared with 54.3 cases per 100,000 population in 2004). The rates in 1-year-olds also fell from 114 cases per 100,000 population in 2004 to 36.5 cases per 100,000 population. The highest rates in 2005 were in adults aged more than 85 years (40.9 cases per 100,000 population, Figure 47). The male to female ratio of IPD cases was 1.3:1.
Figure 47. Notification rate of invasive pneumococcal disease, Australia, 2005, by age group and sex
There were 164 cases of IPD among Indigenous people (9.7% of all cases). This represents a rate of 66 cases per 100,000 population compared with a rate of 7.6 cases per 100,000 population in non-Indigenous people.
Additional data were collected on cases of invasive pneumococcal disease in all Australian jurisdictions during 2005. Analyses of these data are reported separately.17
Poliomyelitis
Case definition – Poliomyelitis Both confirmed cases and probable cases are notified. Confirmed case: Requires isolation of wild-type poliovirus or detection of wild-type poliovirus by nucleic acid testing (confirmed in reference laboratory) and acute flaccid paralysis. Probable case: Requires acute flaccid paralysis not due to other causes as determined by the Polio Expert Committee. |
No cases of poliomyelitis were reported in Australia in 2005.
There were 36 notifications of acute flaccid paralysis (AFP) reported in 2005. Of these 30 occurred in children aged less than 15 years. This represents an AFP notification rate of 0.9 cases per 100,000 children aged less than 15 years which almost reaches the WHO indicator target for adequate AFP reporting of 1 case per 100,000 children. Three AFP cases, 1 aged more than 15 years, had poliovirus isolated from stool samples. The Polio Expert Committee reviewed the 3 cases and classified them as a non-polio AFP, diagnosed as transverse myelitis with the incidental isolation of a Sabin-like virus in 2 cases, while in the third, a type B/E toxin-producing Clostridium botulinum was detected and the case was classified as infant botulism.18
Rubella
Case definition – Rubella Both confirmed cases and probable cases are notified. Confirmed case: Requires isolation of rubella virus OR detection of rubella virus by nucleic acid testing OR IgG seroconversion or significant increase in antibody level or fourfold or greater rise in titre to rubella virus in the absence of recent rubella vaccination, OR detection of rubella specific IgM in the absence of recent rubella vaccination and confirmed in a reference laboratory. Probable case: Requires clinical evidence AND laboratory suggestive evidence OR epidemiological evidence. Laboratory suggestive evidence: In a pregnant patient, detection of rubella-specific IgM that has not been confirmed in a reference laboratory, in the absence of recent rubella vaccination. Clinical evidence: A generalised maculopapular rash AND fever AND arthralgia/arthritis OR lymphadenopathy OR conjunctivitis Epidemiological evidence: An epidemiological link is established when there is: 1. Contact between two people involving a plausible mode of transmission at a time when: a) one of them is likely to be infectious (about one week before to at least four days after appearance of rash) AND b) the other has an illness which starts within 14 and 23 days after this contact AND 2. At least one case in the chain of epidemiologically linked cases (which may involve many cases) is laboratory confirmed. |
In 2005, there were 31 notifications of rubella; 30 confirmed and 1 probable case, which represents a notification rate of 0.2 cases per 100,000 population. This is the lowest rate on record and a 6% reduction on 2004 (33 notifications, 0.2 cases per 100,000 population). In 2005, rubella cases were reported from NSW (10 cases), Queensland (9 cases), and 6 cases each from Victoria and Western Australia. No cases were reported from other jurisdictions.
The male to female ratio of notified cases in 2005 was 1:1, as in 2004. A predominance of male cases was seen in 1999 (M:F ratio: 1.4:1), 2002 (M:F ratio: 3.0:1) and 2003 (M:F ratio: 1.6:1).
Figure 48 shows trends in rubella notification rates in different age groups. The rates in all age groups remained stable in 2005. This pattern of declining rates by age group over time is similar to that for measles, with the exception of higher rubella notification rates in the 15–24 year age group, which persisted until 2002. Rubella cases in this age group were predominantly in males, and this may be related to the schoolgirl measles-mumps-rubella (MMR) vaccination program, prior to the inclusion of boys in 1993.
Figure 48. Trends in notification rate of rubella, Australia, 2005, by age group and sex
There was a single case of congenital rubella reported from Victoria in 2005: born to an unvaccinated overseas-born woman. Altogether there were 13 cases of rubella notified from women of child bearing age (15–49 years) in 2005.
Tetanus
Case definition – Tetanus Only confirmed cases are notified. Confirmed case: Requires isolation of Clostridium tetani from a wound in a compatible clinical setting and prevention of positive tetanospasm in mouse test using a specific tetanus antitoxin OR a clinically compatible illness without other apparent cause. |
In 2005, there were 2 notifications of tetanus. One was an 84 year old female and one was a 74-year old-male.
Childhood vaccination coverage reports
Estimates of vaccination coverage both overall and for individual vaccines for children at 12 months, 24 months and 6 years of age in 2005 are shown in Table 10,Table 11 and Table 12, respectively. During 2005, there were no significant changes in coverage for ‘fully immunised’ and individual vaccines for all 3 milestone ages. It is notable that the estimates for 'fully immunised' and diphtheria-tetans-pertussis (DTP) vaccine at 24 months of age are higher than the 12 months coverage estimates since the 18 months DTPa booster was no longer required from September 2003. Estimates at 6 years of age for all vaccines still remain significantly lower than estimates at the 12 and 24 month milestones.
Table 10. Percentage of Australian children born in 2004 immunised according to data available on the Australian Childhood Immunisation Register, estimate at one year of age
Birth date |
1 Jan–31Mar 2004 | 1 Apr–30 Jun 2004 | 1 Jul–30 Sep 2004 | 1 Oct–31 Dec 2004 |
|---|---|---|---|---|
Vaccine |
% vaccinated | % vaccinated | % vaccinated | % vaccinated |
| DTP | 92.3 |
92.4 |
92.4 |
91.7 |
| Polio | 92.2 |
92.3 |
92.3 |
91.6 |
| Hib | 94.3 |
94.3 |
94.4 |
93.8 |
| Hepatitis B | 94.6 |
94.7 |
94.8 |
94.3 |
| Fully immunised | 91.0 |
91.0 |
91.0 |
90.2 |
Table 11. Percentage of Australian children born in 2003 immunised according to data available on the Australian Childhood Immunisation Register, estimate at two years of age
Birth date |
1 Jan–31 Mar 2003 | 1 Apr–30 Jun 2003 | 1 Jul–30 Sep 2003 | 1 Oct–31 Dec 2003 |
|---|---|---|---|---|
Vaccine |
% vaccinated | % vaccinated | % vaccinated | % vaccinated |
| DTP | 95.5 |
95.3 |
95.2 |
95.1 |
| Polio | 94.9 |
95.2 |
95.2 |
95.0 |
| Hib | 93.3 |
93.5 |
93.6 |
93.5 |
| MMR | 93.4 |
93.7 |
93.8 |
93.8 |
| Hepatitis B | 95.7 |
95.9 |
95.9 |
95.9 |
| Fully immunised | 91.8 |
92.1 |
92.1 |
92.1 |
Table 12. Percentage of Australian children born in 1999 immunised according to data available on the Australian Childhood Immunisation Register, estimate at six years of age
Birth date |
1 Jan–31 Mar 1999 | 1 Apr–30 Jun 1999 | 1 Jul–30 Sep 1999 | 1 Oct–31 Dec 1999 |
|---|---|---|---|---|
Vaccine |
% vaccinated | % vaccinated | % vaccinated | % vaccinated |
| DTP | 84.4 |
84.8 |
85.1 |
84.9 |
| Polio | 84.5 |
85.1 |
85.2 |
84.8 |
| MMR | 84.4 |
84.9 |
85.2 |
84.9 |
| Fully immunised | 83.2 |
83.8 |
84.0 |
83.8 |
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This issue - Vol 31 No 1, March 2007
NNDSS Annual report 2005
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