Effect of the preschool pertussis booster on national notifications of disease in Australia

BACKGROUND

Australia introduced a fifth dose of pertussis vaccine at 4 to 5 years of age in 1994, the first country to do so for some 40 years. We report trends in national pertussis notifications from 1993 to 2001.

METHODS

Notified pertussis cases were analyzed by age and year of disease onset.

RESULTS

Before the fifth dose was introduced, notification rates were higher among 5- to 9-year-olds than 10- to 14-year-olds (76 per 100 000 population vs.65 per 100 000). As more 5- to 9-year-olds became eligible for the fifth dose, their notification rates as a group and by year of age progressively fell to below those of 10- to 14-year-olds, consistent with a vaccine effect. Comparison of notification rates for the epidemic years of 1997 and 2001 shows that 5- to 10-year-olds (eligible for fifth dose) had lower notification rates in 2001 (61 per 100 000) than 5- to 10-year-olds in 1997 (196 per 100 000). This contrasts with children who were not eligible for the fifth dose (12- to 14-year-olds), who had higher notification rates in 2001 (223 per 100 000) than 12- to 14-year-olds in 1997 (160 per 100 000).

CONCLUSIONS

The pattern of age-specific notification rates provides strong evidence that the fifth dose reduced the incidence of pertussis in older children. It will be important to track the impact of the fifth dose on adolescent pertussis notifications to assess the duration of vaccine-acquired immunity.

Effectiveness of pertussis vaccination in New South Wales, Australia, 1996-1998

Pertussis notifications have increased over the past decade in Australia and other industrialised countries. This study estimates the effectiveness of pertussis vaccination in one Australian State (New South Wales, NSW) among children aged less than 14 years, during a period when an Australian whole-cell pertussis vaccine was in routine use. Cases notified with pertussis between 1996 and 1998 and pertussis vaccine coverage estimates from the Australian Childhood Immunisation Register were used. Vaccine effectiveness (VE) was calculated using the screening method, with adjustment for age group, year of disease onset and area of residence. VE was highest (91%) in the youngest age group (8-23 months) and lowest (78%) in the oldest age group (9-13 years). Pertussis vaccination is highly effective at preventing pertussis in NSW children, as measured by notified cases. Ongoing monitoring will be important to evaluate VE following Australia's change to an acellular vaccine based program.

Hepatitis A vaccination options for Australia

The epidemiology of hepatitis A is changing, with an increasing proportion of the population becoming susceptible to infection. The burden of hepatitis A is comparable to that of other vaccine-preventable diseases for which new vaccines are available. Options for vaccination include selective programmes for high-risk groups, which could involve screening prior to vaccination, or universal programmes for infants and/or adolescents. Selective programmes have been shown to be highly cost-effective if well implemented, but there is evidence that they might be poorly implemented. If a universal vaccination programme were considered for Australia, an infant programme, with doses at 18 months and 2 years, possibly with an additional adolescent programme, would be the recommended option. Universal hepatitis A vaccination for infants and/or adolescents is of comparable cost-effectiveness compared with other preventive strategies, but needs to be considered in the context of competing vaccination options.

Using the Australian Childhood Immunisation Register to track the transition from whole-cell to acellular pertussis vaccines

From 1997 to 1999, Australia changed from a whole-cell based pertussis vaccination program to an acellular one. This paper tracks the transition from whole-cell to acellular pertussis vaccines by calculating the number of whole cell (DTPw) and acellular (DTPa) pertussis vaccines recorded on the Australian Childhood Immunisation Register (ACIR) each month from January 1996 to August 2000. The number of combined diphtheria-tetanus (CDT) vaccines, recommended where DTP is contraindicated and for the fifth dose prior to 1994, was also calculated. The use of DTPa increased following its licensing in 1997, with a corresponding decrease in the use of DTPw. The increase was initially greatest in its use as a fourth and fifth dose, for which it was funded at a national level in 1997. Subsequently, a steep increase in its use for the first three doses followed in 1999, coinciding with it becoming free of charge for infants nationally. The use of CDT has decreased markedly since January 1996 and, since March 2000, fewer than 100 CDT vaccines per month were recorded on the ACIR, suggesting that this vaccine is not being inappropriately used.

Estimating immunisation coverage: is the 'third dose assumption' still valid?

Immunisation coverage is calculated from Australian Childhood Immunisation Register (ACIR) data using the 'third dose assumption'. This assumes that if the third in a series of vaccine doses has been recorded on the ACIR, the previous two doses have been received, whether or not they are recorded. The objectives of this study were to validate the 'third dose assumption', and measure the impact of the assumption on immunisation coverage estimates at 12 months of age. A sample of children born in 1999 and assessed as fully immunised at 12 months of age by applying the 'third dose assumption' were selected from the ACIR. Parents were interviewed by telephone to obtain information about vaccinations not recorded on the ACIR. Based on the survey results, the impact of the 'third-dose assumption' on national coverage estimates at 12 months of age was estimated. Of 219 surveyed children assessed as up-to-date at 12 months of age only by applying the 'third dose assumption', 212 (96.8%) met study criteria of 'definite' immunisation for all unrecorded first and second vaccine doses. Of the remaining seven, six believed all doses had been received, while one confirmed that one dose had been missed. The 'third dose assumption' overestimated coverage by 0.2 per cent, based on criteria for 'definite' immunisation. If the assumption were not used, immunisation coverage at 12 months of age in Australia would have been underestimated by 7 per cent. The 'third dose assumption' is valid and important to use in calculating immunisation coverage from the ACIR. Although ACIR reporting and coverage levels continue to improve, under-reporting of vaccine doses due at two and four months of age persists. The 'third dose assumption' may be applicable to comparable immunisation registries in other countries.

A mathematical model to measure the impact of the Measles Control Campaign on the potential for measles transmission in Australia

BACKGROUND

The aims of this study were to determine the impact of the Australian Measles Control Campaign (MCC) on the transmission dynamics of measles by calculating the reproductive number (R) before and after the MCC, and to predict measles control in Australia in the future.

METHODS

A national serosurvey was conducted before and after the MCC. Sera were tested for anti-measles IgG using enzyme immunoassay (EIA). A mathematical model, using serosurvey results and vaccine coverage estimates, was used to calculate the change in R after the MCC.

RESULTS

The values of R calculated before and after the MCC were 0.90 and 0.57. At vaccine coverage levels indicated by the Australian Childhood Immunisation Register (ACIR), the value of R will exceed 1 (the epidemic threshold) in 2007-2008 nationally, and sooner in some regions of Australia. Coverage of at least 84% with two doses of MMR is required to sustain measles control.

CONCLUSIONS

The Australian MCC had a significant impact on the transmission dynamics of measles. However, current vaccine coverage levels may result in indigenous measles transmission by 2007. Sustained efforts are required to improve coverage with two doses of MMR and to ensure elimination of indigenous measles transmission.

Observational methods in epidemiologic assessment of vaccine effectiveness

Observational methods are important in the measurement of vaccine effectiveness (VE) as experimental designs cannot be used for measurement of vaccines already on the vaccination schedule. Furthermore, efficacy measured in clinical trials under ideal conditions may differ to effectiveness in the field under non-ideal conditions and in different populations. In addition to post-licensure surveillance, observational VE studies are particularly important when disease incidence does not predictably decrease with increased vaccine coverage, when high proportions of vaccine failure among reported cases suggest a problem with the vaccine or when issues arise that were not predicted in pre-licensure evaluations. Commonly used study types for evaluating VE include cohort studies, household contact studies, case-control studies, the screening method and case-cohort studies. There are many potential biases in all observational VE studies which should be considered in the study design and analysis stage. Of the five observational study types reviewed, cohort studies undertaken during an outbreak investigation offer the simplest means of VE estimation and is the preferred study design where the situation permits. Where this is not possible the screening method is the most economical and rapid method. It is essential that the effectiveness of all vaccination programs be evaluated. As new vaccines are introduced to the schedule, booster doses are added and the timing of doses changed, the role of observational methods in the evaluation of VE will become even more important. To date, few observational VE studies have been undertaken in Australia, suggesting the under-utilisation of these methods.

National study of adverse reactions after vaccination with bacille Calmette-Guérin

Few large prospective studies of adverse reactions after bacille Calmette-Guérin (BCG) vaccination are available. In a prospective national study of such adverse reactions among 918 subjects (aged 1 day to 54 years) over a 14-month period, 45 vaccinees (5%) reported 53 adverse reactions (23 injection-site abscesses, 14 severe local reactions, 10 cases of lymphadenitis, and 6 other reactions). Only 1% of vaccinees required medical attention. Reactions, particularly lymphadenitis, were significantly less common in infants <6 months old (but not in subjects aged > or =6 months) vaccinated by trained (vs. untrained) providers (relative risk [RR], 0.24; 95% confidence interval [CI], 0.09-0.68). Injection-site abscesses (RR, 2.96; 95% CI, 1.11-7.90) and severe local reactions (RR, 4.93; 95% CI, 1.11-21.90) were significantly more common in older vaccinees. Local reactions were more frequently reported by adult females than by adult males (RR, 7.18; 95% CI, 1.59-32.45). Adverse reactions were not significantly associated with any currently available vaccine batch, previous receipt of BCG vaccine, or concomitant administration of other vaccines.

Factors associated with low uptake of measles and pertussis vaccines--an ecologic study based on the Australian Childhood Immunisation Register

OBJECTIVE

To evaluate the relationships between socio-economic and demographic variables and low immunisation coverage at the national level.

METHODS

The Australian Childhood Immunisation Register (ACIR) contains data at the postcode level on the immunisation status of all children registered with Medicare under the age of seven years. The Australian Bureau of Statistics (ABS) produces a number of indicators of socio-economic status at the postcode level from Census data. These and other ABS demographic data were used to examine the relationship between immunisation coverage and various socio-demographic indicators.

RESULTS

Factors associated with lower immunisation uptake differed in rural and metropolitan areas. High levels of education and occupation and a high proportion of Aboriginal residents were significantly associated with lower coverage only in metropolitan postcodes. High unemployment was associated with lower immunisation coverage only in rural postcodes. A high proportion of late starters to immunisation was the strongest single predictor of coverage and was important in rural and metropolitan postcodes. A high proportion of overseas-born persons and of GP-delivered immunisations was also associated with lower coverage in all areas.

CONCLUSIONS

These data suggest that in metropolitan areas, reasons for low uptake in more advantaged areas require further evaluation. In non-metropolitan areas, low coverage was associated with areas of disadvantage, for which access to services may be more important.

IMPLICATIONS

Children who are late in starting the schedule should be targeted.

Impact of the Australian Measles Control Campaign on immunity to measles and rubella

To evaluate the impact of the 1998 Australian Measles Control Campaign on immunity to measles and rubella, 4400 opportunistically-collected sera, submitted to diagnostic laboratories across Australia from subjects aged 1-49 years, and 3000 from subjects aged 1-18 years, were tested before and after the campaign, respectively. The proportion of individuals aged 1-18 years who were immune to measles rose from 85% before, to 90% after, the campaign (P < 0.001). The greatest increase was in preschool (7%, P < 0.001) and primary school (10%, P < 0.001) children, who were actively targeted by the campaign. Rubella immunity in 1-18 year-olds rose from 83% to 91% (P < 0.0001), again with significant increases in preschool (4%, P = 0.002) and primary school (16%, P < 0.001) children. 94% of individuals aged 19-49 years were immune to rubella. These serosurveys confirm other evidence of the effectiveness of the Australian Measles Control Campaign and demonstrate the value of serosurveillance using opportunistically collected sera.

The Australian Measles Control Campaign, 1998

The 1998 Australian Measles Control Campaign had as its aim improved immunization coverage among children aged 1-12 years and, in the longer term, prevention of measles epidemics. The campaign included mass school-based measles-mumps-rubella vaccination of children aged 5-12 years and a catch-up programme for preschool children. More than 1.33 million children aged 5-12 years were vaccinated at school: serological monitoring showed that 94% of such children were protected after the campaign, whereas only 84% had been protected previously. Among preschool children aged 1-3.5 years the corresponding levels of protection were 89% and 82%. During the six months following the campaign there was a marked reduction in the number of measles cases among children in targeted age groups.

Epidemiology of invasive pneumococcal disease in urban New South Wales, 1997-1999

OBJECTIVES

To describe the serotypes, incidence and morbidity of invasive pneumococcal disease in urban New South Wales.

DESIGN

Prospective laboratory surveillance.

SETTING

Microbiology laboratories and hospitals in the Sydney, Hunter and Illawarra Statistical Divisions of NSW, June 1997 to May 1999.

RESULTS

1270 cases were identified in two years. Incidence of disease was highest in those aged < 2 years (96.4 per 100,000; 95% CI, 83.7-107.9) and > or = 85 years (100.1 per 100,000; 95% CI, 81.8-121.3). Incidence of disease increased significantly from the age of 60 years, compared with low rates in those aged 5-59 years. Underlying diseases predisposing to pneumococcal infection increased with age, from 4% (< 2 years) to 60% (> or = 65 years). A seven-valent conjugate vaccine would have covered 84.8% of serotypes in those aged 0-14 years, falling to 69% in those > or = 15 years. Penicillin resistance was significantly higher in the < 5 years group (19.0%) than in older people (14.6%).

CONCLUSIONS

Incidence of invasive pneumococcal disease was higher in this study using active surveillance than in previous Australian studies. An effective sevenvalent conjugate pneumococcal vaccine could prevent more than 80% of cases in children aged < 5 years.

Conjugate pneumococcal vaccines for non-indigenous children in Australia

Childhood pneumococcal disease is associated with substantial morbidity and mortality, but total disease burden is more difficult to measure than for invasive disease caused by Haemophilus influenzae type b (Hib). A safe, effective seven-valent conjugate pneumococcal vaccine will be available in Australia by early 2001, and will certainly be indicated for high-risk groups and purchased in the private sector, as was Hib vaccine. The status of this vaccine on the Australian Standard Vaccination Schedule will require more detailed consideration of the burden and serotype distribution of pneumococcal disease in Australian children and the vaccine's likely cost-effectiveness. Postmarketing surveillance will be particularly important.

Notifications of vaccine preventable diseases in Australia. Quarterly report (January-March 2000)

Vaccine preventable disease notifications for Australia with disease onset dates between January and March 2000 are reviewed. During this quarter, numbers of notifications for Haemophilus influenzae type b disease and measles were the lowest ever recorded, while those for rubella were the lowest recorded since before the epidemic of spring 1992. These are promising trends that are likely to represent a true reduction in disease incidence. Numbers of pertussis notifications declined compared with the last quarter of 1999, but remain high, making up 88% of notifications for the vaccine preventable diseases reported here.

Survey of pertussis morbidity in adults in western Sydney

OBJECTIVE

To estimate morbidity due to Bordetella pertussis infection in a representative population of Australian adults.

DESIGN

Telephone survey using structured questionnaire.

PARTICIPANTS

Adults (aged 20 years and over) notified with pertussis to a public health unit in western Sydney between 1 December 1997 and 31 May 1998.

MAIN OUTCOME MEASURES

Duration of cough; time to improvement; symptoms and complications; time to diagnosis; health resource use; lost work days.

RESULTS

Of 90 eligible patients, 73 (81%) completed questionnaires. Cough lasted a median of 60 days, but persisted over 90 days in 20 people (27%). Presentation was within a median of seven days of symptom onset, but diagnosis of pertussis took a median of 21 days. Participants reported a mean of 3.7 general practitioner visits and 1.2 prescription drugs. Of those employed, 17 (35%) missed more than five work days (range, 0-93 days).

CONCLUSIONS

B. pertussis infection in adults can result in prolonged, significant disruption to social and working life. Results suggest that, in 1998, there were more than 8000 general practitioner visits and 15,000 lost work days caused by pertussis in Australian adults.

A re-evaluation of immunisation coverage estimates from the Australian Childhood Immunisation Register

Immunisation coverage reporting using data from the Australian Childhood Immunisation Register is likely to underestimate immunisation uptake. Since 1997, several initiatives have been introduced to improve both immunisation uptake and notification of immunisation encounters. These initiatives seemed likely to have changed previous coverage estimates. Re-calculation of immunisation coverage estimates for the previously reported cohorts was undertaken. This used current Australian Childhood Immunisation Register data--especially the immunisation history form and the impact of catch-up immunisations--to evaluate delayed reporting. Previous coverage estimates published in Communicable Diseases Intelligence were shown to be at least 2% to 4% below estimates based on data now held by the Australian Childhood Immunisation Register, with greater differences observed in particular jurisdictions.

Pneumococcal disease in Australia

The proceedings of the Pneumococcal Disease in Australia Workshop, held on 26-27 March 1999 are presented in this report. The world-wide epidemiology of the pneumococcus, with its predilection for the very young and the very old, differs between the developing and the developed world, and between indigenous and non-indigenous populations. Sources of data on pneumococcal disease in each of the Australian States, clinical aspects of invasive and non-invasive disease, and the role of the public health laboratory in surveillance of serotypes and antimicrobial sensitivity, both nationally and over time, were discussed at the Workshop. Polysaccharide pneumococcal vaccines are recommended for those over 65 years of age and for at-risk groups, but are supplied free of charge only in Victoria and for indigenous Australians over 50 years of age. Children will require conjugate vaccines, which are likely to be licensed in the United States of America early in 2000. In Australia indigenous children, especially in rural areas, will be the priority group for conjugate vaccines.

Factors influencing vaccination uptake. Workshop report. Current Australian research on the behavioural, social and demographic factors influencing immunisation, Royal Alexandra Hospital for Children, Sydney, March 1998

Current Australian research on factors influencing vaccination was discussed at a workshop held at the Royal Alexandra Hospital for Children, Sydney, in March 1998, sponsored by the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases (NCIRS). The application of decision making theory to vaccination behaviour, the expectations and experiences of mothers, and reasons why parents fail to vaccinate their children were considered. Mothers' perceptions of the risks of vaccines, preferences of parents and providers for the mode of vaccine delivery, and community and social factors were all found to be part of the framework within which vaccination is accepted in Australia. Consumer considerations, media influences and overseas comparisons were discussed.

Immunisation coverage reporting through the Australian Childhood Immunisation Register--an evaluation of the third-dose assumption

OBJECTIVE

The Australian Childhood Immunisation Register (ACIR) currently classifies those children who have the third dose recorded as fully immunised at 12 months of age, even if records of earlier doses are missing. This analysis assesses the impact this "third-dose assumption" has on immunisation coverage estimates for children aged 12 months.

METHODS

ACIR records from three equally spaced cohorts of children at 12 months of age, which relied on the third-dose assumption, were examined for variation in doses and vaccine types recorded by jurisdiction and Medicare registration status.

RESULTS

Although the percentage reduction in coverage without application of the third-dose assumption decreased through the three cohorts examined, the proportion classified as fully immunised still decreased by 11-12% (to < 75%) if the third-dose assumption was not used in the most recent cohort. "Fully immunised" status among children with delayed Medicare registration or in jurisdictions with a high proportion of paper reporting to the ACIR was disproportionately reduced without use of the assumption.

CONCLUSIONS AND IMPLICATIONS

While independent sources of data continue to show that the ACIR incorrectly classifies some children as not fully immunised even with the third-dose assumption, its use seems appropriate for reporting population trends in immunisation coverage. Earlier Medicare registration and increased electronic reporting to the ACIR, together with incentives for parents and providers to ensure complete ACIR records, should eventually eliminate the need for the third-dose assumption.

A population-based study of children with cerebral tuberculosis in New South Wales

OBJECTIVE

To determine the incidence of childhood cerebral tuberculosis (tuberculous meningitis [TBM] and tuberculoma) in a defined population.

DESIGN

Retrospective, population-based study.

SETTING AND PARTICIPANTS

All resident children aged up to 14 years in New South Wales diagnosed with cerebral tuberculosis, from 1982 to 1996.

MAIN OUTCOME MEASURE

Population-based incidence of childhood TBM.

RESULTS

10 children with TBM and one with tuberculoma were identified in the 15 years. The incidence of TBM was 0.053 (95% CI, 0.025-0.097) per 100,000. Eight of the 10 TBM patients were born in Australia and five were of white European origin. Only one had been vaccinated with BCG vaccine. Three of the children died.

CONCLUSIONS

The incidence of childhood TBM in New South Wales is low, and comparable with that in other First World countries.

Immunisation coverage in Australian children: a systematic review 1990-1998

The Australian Childhood Immunisation Register (ACIR) commenced operation in January 1996 and provides a comprehensive database of children's immunisations in Australia. The ACIR enables implementation of an immunisation recall and reminder system and improved surveillance and reporting of immunisation coverage. Before the introduction of the ACIR, the methods used in assessing coverage varied widely in design and quality, with few studies measuring coverage at national or statewide level. This is a systematic review of the scope and reliability of estimates of immunisation coverage available in Australia from 1990 to 1998. A total of 108 studies were identified of which 51 were classified as higher quality based on a range of criteria including whether they had a response rate of 50% or better.

Incidence of invasive pneumococcal disease in Sydney children, 1991-96

OBJECTIVE

Few data are available on invasive disease due to Streptococcus pneumoniae in representative Australian childhood populations. This study aimed to determine the age-specific incidence of invasive pneumococcal disease in Sydney children.

METHODOLOGY

Population-based prospective study where isolates of Streptococcus pneumoniae from normally sterile sites were identified through an established laboratory surveillance network. Isolates came from children aged under 15 years living within the boundaries of Central, Eastern. Southern, Western and South-western Sydney Area Health Services from 1 July 1991 to 30 June 1996.

RESULTS

Invasive pneumococcal disease was identified in 320 children during a 5-year period, of whom 193 (60%) were under 2 years of age. The incidence per 100,000 children was 12.7 per 100,000 (95% CI: 11.4-14.2/100,000) under 15 years; 31.7 (95% CI 28.1-35.7) under 5 years, and 45.5 (95% CI 38.9-53.3) under 2 years. The incidence of pneumococcal meningitis in children aged under 2 years was 10.5 per 100,000 (95% CI: 7.4-14.5/100,000).

CONCLUSIONS

The incidence of childhood invasive pneumococcal disease in Sydney was stable during 1991-96 and comparable to rates reported from other industrialized countries. There was no evidence of any change in pneumococcal disease incidence with reduction in invasive Haemophilus influenzae type b (Hib) disease following introduction of Hib immunization.

Measuring immunisation coverage in Australia. A review of the Australian Childhood Immunisation Register

BACKGROUND

Before the establishment of the Australian Childhood Immunisation Register (ACIR), measurement of childhood immunisation coverage in Australia involved a variety of methods at varying intervals by general practice (GP) divisions, state health departments and the Australian Bureau of Statistics. Such surveys may underestimate (child health records) or overestimate (parental recall) true immunisation coverage.

OBJECTIVE

The establishment of the ACIR in 1996 (a world first), was a huge undertaking involving 15,000 immunisation providers (60% GPs) notifying over 3 million immunisations annually. This review summarises the operation of the ACIR, how it calculates coverage, the accuracy of estimates from the ACIR and how Australia's immunisation coverage compares with that of other similar countries. Currently, the accuracy of the records on the register is questioned, especially in urban areas, but available data suggest that failure to report to the ACIR is the main source of data discrepancies.

DISCUSSION

The ACIR has the potential to measure immunisation coverage at any practice or local level with accuracy and timeliness. With full provider participation, the ACIR is capable of identifying areas of low immunisation coverage for targeted interventions and will play a key role in the current measles campaign, the General Practice Immunisation Incentives scheme and in payments to parents. Achieving the highest possible completeness and timeliness of the ACIR is in the interests of providers, consumers and health planners.

Parent and general practitioner preferences for infant immunisation. Reactogenicity or multiple injections?

AIM

To explore the relative importance parents and general practitioners place on less reactogenic vaccines and multiple injections at each childhood immunisation encounter.

METHOD

A random sample of western Sydney parents (n = 162) and GPs (n = 154) completed telephone questionnaires about their preference for either a single injection of pentavalent vaccine (whole-cell pertussis/diphtheria/tetanus/Hib/hepatitis B), or regimen containing the less reactogenic acellular pertussis vaccine requiring two separate injections (acellular pertussis/diphtheria/tetanus and Hib or three separate injections (acellular pertussis/diphtheria/tetanus and Hib and hepatitis B). Potential confounders were examined by univariate and multivariate analysis.

RESULTS

Regimens containing acellular pertussis vaccine (2 injections or 3 injections) were preferred by 72% and 58% of parents respectively. Those whose children were already vaccinated were less concerned about side effects and were twice (or = 2.0, 95% CI 1.0-4.0) as likely to select the pentavalent (single injection) option. 69% and 77% of GPs preferred the pentavalent rather than the two or three injection acellular option, although previous experience with a systemic adverse reaction to immunisation increased their preference for the acellular pertussis vaccine (or = 2.9, 95% CI 1.1-7.6). Only 54% of parents and 28% of GPs favoured three injections at one visit.

CONCLUSION

Parent and GP concerns regarding reactogenicity and multiple injections differ. Parents are more concerned about vaccine reactogenicity than multiple injections. However, if the GP recommends a particular regimen, it is likely to be accepted by parents.

Measles control in Australia. Report of the Measles Control in Australia Workshop, 5 November 1997

The proceedings of the Measles Control in Australia Workshop held on 5 November 1998 are presented in this report. Prompted by the possibility of a global elimination campaign in the near future the Workshop considered the factors involved in elimination of measles from Australia. Epidemiology, surveillance, laboratory diagnosis methods, mathematical modelling, and the cost and logistics were all addressed. Mass vaccination for all 2-18 year olds, and a routine 2-dose regimen with scheduled doses at 12 months and school entry were recommended. Intensified surveillance, based on a sensitive case definition and laboratory confirmation (measles specific IgM) of suspected cases was identified as a crucial component of the campaign. The continuation of high vaccination coverage for each of the two doses would be essential to maintain elimination once established.

Dexamethasone as adjunctive therapy in bacterial meningitis. A meta-analysis of randomized clinical trials since 1988

OBJECTIVE

To evaluate the effectiveness of dexamethasone in bacterial meningitis in the subcategories of causative organism and timing and nature of antibiotic therapy.

DATA SOURCES

MEDLINE, HEALTHLINE, and AIDSLINE were searched with the Medical Subject Headings "dexamethasone" and "meningitis" in any language. Bibliographies, conference abstracts, and the authors of identified studies were consulted.

STUDY SELECTION

Randomized, concurrently controlled trials of dexamethasone therapy in childhood bacterial meningitis published from 1988 to November 1996 were selected. Of 16 studies identified, 5 were not eligible.

DATA EXTRACTION

Data were extracted by means of standard outcomes in a protocol sent to all principal authors.

DATA SYNTHESIS

Random-effects meta-analysis models were used to obtain summary estimates. As the incidence of severe hearing loss differed significantly by organism among control subjects, organism-specific estimates were used. In Haemophilus influenzae type b meningitis, dexamethasone reduced severe hearing loss overall (combined odds ratio [OR], 0.31; 95% confidence interval [CI], 0.14-0.69). Similar ORs were obtained after studies were stratified by the timing of administration of dexamethasone (before or with antibiotics vs later) or by type of antibiotic (cefuroxime vs other). In pneumococcal meningitis, only studies in which dexamethasone was given early suggested protection, which was significant for severe hearing loss (combined OR, 0.09; 95% CI, 0.0-0.71) and approached significance for any neurological or hearing deficit (combined OR, 0.23; 95% CI, 0.04-1.05). For all organisms combined, the pooled OR suggested protection against neurological deficits other than hearing loss but was not significant (OR, 0.59; 95% CI, 0.34-1.02). Outcomes were similar in studies that used 2 vs more than 2 days of dexamethasone therapy. Adverse effects were not significantly increased with dexamethasone except for secondary fever. The incidence of gastrointestinal tract bleeding increased with longer duration of dexamethasone treatment (0.5% in controls, 0.8% with 2 days of treatment, 3.0% with 4 days of treatment).

CONCLUSIONS

The available evidence on adjunctive dexamethasone therapy confirms benefit for H influenzae type b meningitis and, if commenced with or before parenteral antibiotics, suggests benefit for pneumococcal meningitis in childhood. Limiting dexamethasone therapy to 2 days may be optimal.

Rotavirus gastroenteritis: impact on young children, their families and the health care system

OBJECTIVE

To assess the impact of rotavirus gastroenteritis on young children attending a paediatric hospital, their families and the health care system.

DESIGN

Cross-sectional descriptive survey.

SETTING

New Children's Hospital (Royal Alexandra Hospital for Children), Sydney, New South Wales, 15 July to 4 October 1996.

PARTICIPANTS

Children aged under three years attending the Emergency Department with acute diarrhoea as the presenting symptom.

OUTCOME MEASURES

Cases of rotavirus infection confirmed by enzyme-linked immunosorbent assay by age; rotavirus serotype; gastroenteritis severity score; estimated costs to parents (lost pay or leave, travel, medication and other expenses) and to the health care system (visits to Emergency Department and other health care workers, hospital admissions).

RESULTS

280 children were recruited (73% of 384 children who met the inclusion criteria and 27% of the 1037 aged under three years with acute gastroenteritis). Rotavirus was detected in 188 of the 280 (67%); most isolates were serotype G1 (86% of the 174 serotyped). Of the 188 children with confirmed rotavirus infection 78% were aged 7-24 months and 82% visited at least one other health care worker, usually a general practitioner. Seventy (37% of the 188) were admitted to hospital; 33 of these (47%) were aged 13-24 months. Estimated mean total cost per episode of rotavirus gastroenteritis was $1744 for children admitted to hospital and $441 for children not admitted. The mean cost to families was $493 for children admitted to hospital and $228 for children not admitted.

CONCLUSIONS

Rotavirus gastroenteritis has a significant impact on young children, their families and the health care system. Prevention of severe disease through routine infant vaccination would be potentially cost-effective.

Antibiotic management of pneumococcal infections in an era of increased resistance

Pneumococci are a leading cause of bacterial meningitis and bacteraemia, as well as pneumonia, otitis media and sinusitis in childhood. These organisms recently have shown a dramatic increase in antibiotic resistance. Penicillin-resistant pneumococci are of special concern as they are often resistant to other unrelated antibiotics. This is of particular significance to Aboriginal children who have among the highest rates of pneumococcal infection in the world. Laboratories should now test all invasive pneumococcal isolates for penicillin and third generation cephalosporin resistance. Local treatment guidelines are required for pneumococcal infections, especially for meningitis, taking into account the prevalence of resistant strains within the community. At present, penicillin and amoxycillin remain the drugs of choice for pneumococcal infections, with the exception of meningitis where initial empirical therapy must be with a third generation cephalosporin. Judicious antibiotic use, which avoids over-prescribing and unnecessary use of broad-spectrum agents, improved living standards in underprivileged communities and introduction of an effective conjugate vaccine, able to reduce the rates of pneumococcal infection and hopefully colonization, may limit the spread of resistant strains.

Randomized prospective trial comparing ileal pouch-anal anastomosis performed by excising the anal mucosa to ileal pouch-anal anastomosis performed by preserving the anal mucosa

OBJECTIVE

The purpose of the study is to compare the results of ileal pouch-anal anastomosis (IPAA) in patients in whom the anal mucosa is excised by handsewn techniques to those in whom the mucosa is preserved using stapling techniques.

SUMMARY BACKGROUND DATA

Ileal pouch-anal anastomosis is the operation of choice for patients with chronic ulcerative colitis requiring proctocolectomy. Controversy exists over whether preserving the transitional mucosa of the anal canal improves outcomes.

METHODS

Forty-one patients (23 men, 18 women) were randomized to either endorectal mucosectomy and handsewn IPAA or to double-stapled IPAA, which spared the anal transition zone. All patients were diverted for 2 to 3 months. Nine patients were excluded. Preoperative functional status was assessed by questionnaire and anal manometry. Twenty-four patients underwent more extensive physiologic evaluation, including scintigraphic anopouch angle studies and pudendel never terminal motor latency a mean of 6 months after surgery. Quality of life similarly was estimated before surgery and after surgery. Univariate analysis using Wilcoxon test was used to assess differences between groups.

RESULTS

The two groups were identical demographically. Overall outcomes in both groups were good. Thirty-three percent of patients who underwent the handsewn technique and 35% of patients who underwent the double-stapled technique experienced a postoperative complication. Resting anal canal pressures were higher in the patients who underwent the stapled technique, but other physiologic parameters were similar between groups. Night-time fecal incontinence occurred less frequently in the stapled group but not significantly. The number of stools per 24 hours decreased from preoperative values in both groups. After IPAA, quality of life improved promptly in both groups.

CONCLUSIONS

Stapled IPAA, which preserves the mucosa of the anal transition zone, confers no apparent early advantage in terms of decreased stool frequency or fewer episodes of fecal incontinence compared to handsewn IPAA, which excises the mucosa. Higher resting pressures in the stapled group coupled with a trend toward less night-time incontinence, however, may portend better function in the stapled group over time. Both operations are safe and result in rapid and profound improvement in quality of life.

Invasive pneumococcal infection in children, 1981-92: a hospital-based study

OBJECTIVE

To document the pattern and sequelae of invasive pneumococcal infection in hospitalized children.

METHODOLOGY

Retrospective review of Streptococcus pneumoniae (Sp) isolates from normally sterile sites from 1981 to 1992 at three paediatric centres in Sydney for demographic data, spectrum of disease, predisposing conditions, mortality, and sequelae from meningitis.

RESULTS

Four hundred and thirty-one episodes in 417 patients were identified. Foci of infection were: meningitis, 34%; pneumonia, 29%; bacteraemia without apparent focus, 30%; and other foci, 7%. Sixty-one per cent of all cases and 64% of cases with meningitis were less than 2 years old. Predisposing conditions were present in 37%, were significantly more common in patients over age 2 years and were more common with foci other than meningitis. Overall mortality was 6.6% whereas the mortality for those with meningitis was 8%. Neurological sequelae were identified in 34% of previously normal children, and severe hearing loss occurred in 11.5%.

CONCLUSIONS

The high morbidity and mortality from invasive pneumococcal infection in children justifies further evaluation of preventive strategies.

The impact of vaccination against invasive Haemophilus influenzae type b disease in the Sydney region

OBJECTIVE

To evaluate the incidence of invasive Haemophilus influenzae type b (Hib) disease relative to rates of Hib vaccination in a well defined population.

DESIGN AND SUBJECTS

Cases of invasive Hib disease were identified by active laboratory surveillance for the period 1989-1994, and retrospectively for 1985-1987. Vaccination rates were determined by telephone interview of families with children aged 0-4 years, identified in a random telephone directory sample of 4000 households. The receipt and time of vaccination were validated from general practitioner records for a 50% subsample of children.

SETTING

Sydney Statistical Division, with a population of 263,758 children aged 0-4 years in 1990.

RESULTS

Hib vaccination rates were relatively low before the introduction of government-funded vaccination programs in May 1993, especially for children under 18 months for whom multiple doses are required. Rates rose from fewer than 9% (95% CI, 4%-13%) in May 1993 to 48% (CI, 40%-56%) in August 1993 for children under 18 months, and from 31% (CI, 26%-36%) to 45% (CI, 40%-51%) for children aged 19-60 months. The age-specific incidence of Hib disease was inversely related to the vaccination rate. Forecasting of Hib disease incidence by the Box-Jenkins method showed that from September 1993, when about a 50% vaccine uptake was achieved in the eligible age group, overall incidence was substantially lower than expected.

CONCLUSIONS

These data provide good evidence that the decrease in Hib disease incidence in 1993-1994 is an effect of vaccination, and not annual or seasonal variation. The impact of Hib vaccination appears to have been greater than would be expected from protection of vaccinated children alone. Invasive Hib disease is likely soon to become a rare cause of serious childhood infection in Australia.

Indeterminate colitis. Long-term outcome in patients after ileal pouch-anal anastomosis

Uncertainty persists concerning the long-term results of ileal pouch-anal anastomosis performed for indeterminate colitis.

PURPOSE

This study was designed to compare functional outcomes of ileal pouch-anal anastomosis in patients with typical chronic ulcerative colitis and indeterminate colitis.

METHOD

Seventy-one ileoanal pouch patients were identified with a diagnosis of indeterminate colitis. Mean follow-up was 56 months. Outcomes were compared with 1,232 chronic ulcerative colitis patients after ileal pouch-anal anastomosis. Mean follow-up was 60 months.

RESULTS

(mean +/- SD) There was no difference in the frequency of daily bowel movements (indeterminate colitis, 7 +/- 3, vs. chronic ulcerative colitis, 7 +/- 2). Daytime and nighttime incontinence rates were likewise similar. Prevalence of pouchitis was identical (33 percent). However, failure rate was higher in the indeterminate colitis group (indeterminate colitis, 19 percent, vs. chronic ulcerative colitis, 8 percent; (P = 0.03)).

CONCLUSIONS

At a mean of nearly five years after surgery, failure appears to occur more frequently in patients with indeterminate colitis than in patients with chronic ulcerative colitis. However, the great majority of indeterminate colitis patients (> 80 percent) have long-term functional results identical to those of patients with chronic ulcerative colitis.

Double-stapled vs. handsewn ileal pouch-anal anastomosis in patients with chronic ulcerative colitis

Proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the treatment of choice for most patients with chronic ulcerative colitis. Whether or not a double-stapled technique, which should preserve the anal transition zone and avoid prolonged and dilation, facilitates superior fecal continence compared with conventional mucosal resection and handsewn anastomosis is unknown.

PURPOSE

The aim of this study was to compare functional results after double-stapled and handsewn IPAA.

METHODS

Twenty-seven consecutive patients (13 females, 14 males; mean age, 37 years) who had proctocolectomy and double-stapled IPAA (J) for chronic ulcerative colitis were identified. Each was matched by sex, age, and surgeon to a control who had undergone a conventional handsewn anastomosis. Functional results at six months after ileostomy closure were compared.

RESULTS

Median stool frequency in each group was seven. The prevalence of pouchitis was 22 percent in both groups. One pouch failure occurred in each group. The percentage of patients from the double-stapled group with daytime spotting was similar to that of the handsewn group (18 percent vs. 26 percent, P > 0.5). Nighttime soiling rates were similar as well (41 percent vs. 48 percent, P > 0.5).

CONCLUSIONS

Double-stapled IPAA appears to convey no early functional advantage over handsewn IPAA for chronic ulcerative colitis.

Comparing functional results one year and ten years after ileal pouch-anal anastomosis for chronic ulcerative colitis

Proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the treatment of choice for most patients with chronic ulcerative colitis. Long-term results, however remain undefined; the major concern is that function may deteriorate.

PURPOSE

The aim of this study was to assess functional outcome in a subgroup of patients who have an IPAA for chronic ulcerative colitis for > 10 years.

METHODS

Among 1400 IPAA patients, 75 consecutive subjects (31 females and 44 males; median age 31 at operation) were identified who had the procedure prior to 1982. All patients had functional results recorded 1 year and 10 years following ileostomy closure.

RESULTS

There were four deaths during the follow-up period; none were pouch related. Two patients refused ileostomy closure. Of the remaining 69 patients, there were 8 (11 percent) failures, leaving 61 subjects available for study. Stool frequency (7 +/- 3, mean +/- SD) remained unchanged. Of the 50 subjects with initially excellent daytime continence, 39 (78 percent) remained the same, 10 (20 percent) developed minor incontinence, and 1 developed poor control after 10 years. Four of 10 subjects (40 percent) with initial minor daytime incontinence remained unchanged, 4 (40 percent) improved, and 2 (20 percent) worsened. The one subject with poor control at one year was unchanged. Nocturnal fecal spotting increased over the 10-year period but not significantly (38 percent vs. 52 percent; P = 0.08).

CONCLUSIONS

After IPAA, functional results in terms of stool frequency and rate of fecal incontinence did not deteriorate with time.

Pathophysiology of colonic motility disorders

When no identifiable organic cause for colonic symptoms can be found, it is easy for the busy clinician to label the patient neurotic. It is evident that many of these "functional" disorders do reflect an underlying motility disorder, although our understanding is far from clear. However, currently, patients with severe constipation are evaluated in a much more rational manner and, as a consequence, are offered a reasonable therapeutic approach that can be predicted to have a good chance for success. We can hope that as our understanding of irritable bowel syndrome is strengthened, treatment will become more efficacious than the unproved and costly medications that are in use currently. Until dietary modification becomes commonplace, it is unlikely that the incidence of diverticular disease or its complications will change. Already, our understanding of ileus has allowed us to realize the benefits of laparoscopic surgery, and as our knowledge of the various gut hormones and the inhibitory role that some play in intestinal motility grows, ileus, and its resulting prolongation of hospital stay, may become less problematic.