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P B McIntyre

Publications and source records attributed to P B McIntyre.

At least 19 recordsLinked to original sources
PubMed2006

Population-based seroprevalence of Neisseria meningitidis serogroup C capsular antibody before the introduction of conjugate vaccine, in Australia.

Neisseria meningitidis serogroup C (NMC) conjugate vaccine was introduced, in Australia, in 2003. Our aims were to determine pre-immunisation IgG NMC seroprevalence and evaluate an enzyme-linked immunosorbent assay (ELISA), previously validated against the serum bactericidal assay (SBA). 2409 sera, collected in 2002, from subjects aged 2-34 years, were tested. The geometric mean concentration (GMC) of NMC anticapsular IgG was 0.38 U/mL in subjects under 19 years and it increased to 0.67 U/mL for those aged 30-34 years. Variation in GMC correlated with reported NMC disease incidence and was higher in males than females (0.52 U/mL versus 0.41 U/mL; p=0.005). The ELISA appears suitable for serosurveillance but the IgG level that correlates with protection needs further investigation. Serosurveys will be repeated to monitor the impact of vaccination.

Adolescent↗
PubMed2006

Evaluation of two enzyme immunoassays for detection of immunoglobulin G antibodies to mumps virus.

To determine suitability for national serosurveys, we compared two commercial enzyme-linked immunosorbent assays (ELISAs) for mumps antibody, Enzygnost Anti-Parotitis-Virus/IgG (which uses a whole-virus antigen) and Microimmune Mumps IgG Screen ELISA (which uses a recombinant nucleoprotein antigen), by testing 1,915 opportunistically collected sera submitted to diagnostic laboratories across Australia in 1997 to 1998. The proportion of positive results increased with age in both ELISAs but was significantly higher with the Microimmune than with the Enzygnost ELISA overall (88% versus 63%; P < 0.01) and in all age groups. However, the proportion of equivocal results was significantly higher with the Enzygnost than with the Microimmune ELISA (9% versus 4%; P < 0.01). Of the 572 sera with discrepant or equivocal results, 508 had sufficient sample remaining to perform the neutralization test (NT). A proportion with concordant results in both ELISAs were also tested by the NT. For sera with discrepant results, there was significantly better agreement between the NT and Microimmune than between the NT and Enzygnost (310/444 [70%] versus 135/348 [39%]; P < 0.01). Of 64 sera with equivocal Microimmune results, 45 (70%) were positive in the NT compared with 140 of 160 (88%) equivocal Enzygnost results (P < 0.01). Compared with the NT, the Microimmune ELISA is more sensitive (96% versus 80%) but apparently less specific (36% versus 85%) than the Enzygnost ELISA. However, this is likely to be due to the generally lower sensitivity of the NT, since the Microimmune results reflect expected seroprevalence, based on vaccine uptake in the age groups studied. We conclude that the Microimmune ELISA is a more appropriate assay than the Enzygnost ELISA for estimation of mumps seroprevalence.

Adolescent↗
PubMed2005

A boarding school outbreak of pertussis in adolescents: value of laboratory diagnostic methods.

Culture for Bordetella pertussis (B. pertussis) is the traditional gold standard for laboratory diagnosis of pertussis but is insensitive, especially later in the course of illness and in vaccinated persons. Interpretation of serology is limited by the lack of an appropriate reference standard. An outbreak of pertussis in a crowded boarding-school dormitory allowed evaluation of laboratory correlates of infection. Questionnaires, serum samples and throat swabs were collected from members of the exposed group. Serum samples from unexposed controls of a similar age group were used for comparison. B. pertussis PCR was performed on throat swabs, and sera were tested for IgA antibodies against whole-cell (WC) B. pertussis antigen and IgG antibodies to pertussis toxin (PT). The Centers for Disease Control and Prevention definition for pertussis was used to define clinical cases. We evaluated the use of a previously published cut-off for PT IgG of 125 EIA units (EU)/ml. Completed questionnaires were obtained from 115 students, of whom 85 (74%) reported coughing symptoms, including 32 (28%) who met the clinical case definition for pertussis. B. pertussis was detected by PCR in 17 (15%) and WC IgA in 22 (19%) students; neither correlated with symptoms, but dormitory of residence strongly predicted PCR status. The mean PT IgG geometric mean concentration, in this situation of high pertussis exposure, correlated with severity of symptoms and was significantly higher in both symptomatic and asymptomatic children exposed during the outbreak (P < 0.001) than in control children. A cut-off for PT IgG of 125 EU/ml was too high in an outbreak situation to be sensitive enough to identify pertussis cases. A case of pertussis in a crowded boarding-school dormitory resulted rapidly in an outbreak. Serology and PCR were useful in identifying the outbreak and commencing disease control measures. The use of serology has mostly been evaluated in community serosurveys, where it is not possible to determine if immunity reflects vaccination, asymptomatic disease or symptomatic disease. This outbreak gave us the opportunity to evaluate the value of serology and PCR in the presence of confirmed exposure to pertussis.

Adolescent↗
PubMed2005

A population based study of the impact of corticosteroid therapy and delayed diagnosis on the outcome of childhood pneumococcal meningitis.

BACKGROUND: Despite an extensive literature, the impact of both adjunctive steroid therapy and delayed diagnosis on the outcome of childhood pneumococcal meningitis is controversial. AIM: To determine the independent contribution of corticosteroid therapy and delayed diagnosis on the outcome of childhood pneumococcal meningitis in a representative population with good access to medical services. METHODS: Data were obtained from laboratories and hospital records to assemble a population register in Sydney, Australia, 1994-99. Follow up questionnaires were completed by attending physicians. RESULTS: A total of 122 cases of pneumococcal meningitis aged 0-14 years were identified. Almost 50% of 120 children with available records either died (n = 15) or had permanent neurological impairment (n = 39). Early use (before or with parenteral antibiotics) of corticosteroids protected against death or severe morbidity (adjusted OR 0.21, 95% CI 0.05 to 0.77). Delayed diagnosis was associated with increased morbidity in survivors (OR 3.4, 95% CI 1.03 to 11.4) but not with increased mortality. CONCLUSION: In a population with good access to health care and after adjusting for other known prognostic variables, early recognition of pneumococcal meningitis and treatment with adjunctive dexamethasone significantly improves outcomes. These data add to those from randomised controlled trials. Implementation requires development of protocols and guidelines for use in emergency departments.

Administration, Oral↗
PubMed2005

Childhood asthma diagnosis and use of asthma medication.

AIM: To determine the burden of asthma in children. METHODS: A cross sectional, randomised, computer assisted telephone survey of a community based sample of 2020 children aged 5-14 years in western Sydney (New South Wales) over a 20 day period from June 2000 to July 2000. RESULTS: Main outcome measures were carer reported history of asthma diagnosis, hospital presentation/admission for asthma, recent use of anti-asthma medications, and recent respiratory symptoms. Diagnosed asthma was reported in 31% (of whom 42% were diagnosed aged 2 years or under) and asthma medications used in the previous year by 21% of children. Factors significantly associated with a reported asthma diagnosis included: male gender (OR: 1.51), birth in Australia (OR: 1.64), living in an English speaking household (OR: 1.47), Aboriginality (OR: 2.32), possession of a health care card (OR: 1.28), previous pneumonia (OR: 2.4) or pertussis (OR: 2.0), and a recent episode of croup (OR: 1.9). Exposure to tobacco smoke and immunisation status were not significant. DISCUSSION: We confirm a high prevalence of asthma and medication use for asthma. The high proportion of children diagnosed asthmatic at 2 years or under (when asthma cannot be diagnosed reliably) suggests overdiagnosis of asthma may contribute to the apparent high prevalence.

Adolescent↗
PubMed2004

Pertussis vaccination strategies for neonates--an exploratory cost-effectiveness analysis.

Hospitalisation and death from pertussis in highly immunised populations largely occurs before the first vaccination at 2 months. A Markov model was constructed to estimate the costs and health consequences of three strategies to reduce pertussis over the first 6 months of an infant's life. Earlier vaccination (at either birth or 1 month in addition to current practice) or vaccination of the parents soon after birth was compared with the current practice of vaccination at 2, 4 and 6 months. The model was populated using data on the incidence and costs from Australia. Disability-adjusted life-years (DALYs) were used as the primary outcome measure. The cost to the Australian public health system was chosen as the economic perspective, and Monte-Carlo simulations were used to accommodate uncertainties in the variables. Vaccination at birth was estimated to cost (S.D.) an additional A$33.21 (A$1.60) per infant and to reduce cases, deaths and DALYs by 45%. Vaccination at 1 month was estimated to cost an additional A$43.24 (A$8.98) per infant and to reduce morbidity by approximately 25%. Parental vaccination at birth was the most expensive alternative, costing an additional A$73.38 (A$4.98) per infant and reducing pertussis morbidity by 38%. The costs per DALY averted were A$330,175 (A$15,461) A$735,994 (A$147,679) and A$787,504 (A$48,075) for the birth, 1 month and parental vaccination strategies, respectively. Changing the estimated factor by which hospitalisations and deaths are under-reported, and the efficacy of early vaccination, had large effects on results. Parental vaccination at birth was most cost-effective where protection persisted for subsequent children. The birth vaccination strategy appears to offer the greatest potential benefit for one-child families, but the efficacy at birth (and 1 month) needs to be established.

Algorithms↗
PubMed2004

Temporal trends in circulating Bordetella pertussis strains in Australia.

Australia experienced a resurgence of pertussis in the 1990s despite improved vaccine coverage. Although much of the increase was attributable to increased detection of cases in older persons with waning immunity by serology, vaccine changes or alterations in circulating Bordetella pertussis strains may also have contributed. We determined the frequency of variants of B. pertussis pertactin (prn), and pertussis toxin subunit 1 (ptxS1) genes, restriction fragment length polymorphism (RFLP) types and fimbrial serotypes prevalent in Australia prior to, and during the 1990s. Ampoules of the whole-cell vaccine in use prior to 1999 and 84 B. pertussis isolates stored between 1967 and 1998 by laboratories around Australia were analysed. One pertactin allele, Prn3, not detected before 1985, was found in 24 out of 57 (42%) isolates between 1989 and 1998 (P<0.0001). PtxS1A was found in all isolates. IS1002 type 29, found in 17 out of 31 (55%) isolates tested, was the predominant RFLP type. The only difference in fimbrial serotype distribution between the time-periods was an increase in serotype 3 (P=0.054). The whole-cell vaccine contained only the alleles prn1 and ptxS1A. Antigenic shift in B. pertussis may have contributed to the re-emergence of pertussis in Australia. Monitoring these trends will be important as acellular vaccines are introduced and changes are made to pertussis vaccine schedules.

Bacteremia↗
PubMed2003

Community-based estimates of incidence and risk factors for childhood pneumonia in Western Sydney.

The aim was to estimate the community incidence and risk factors for all-cause pneumonia in children in Western Sydney, Australia. A cross-sectional randomized computer-assisted telephone interview was conducted in July 2000, in Western Sydney. Parents of 2020 children aged between 5 and 14 years were interviewed about their child's respiratory health since birth. No verification of reported diagnosis was available. Logistic regression analysis was used to determine risk factors for pneumonia. A lifetime diagnosis of pneumonia was reported in 137/2020 (68%) children, giving an estimated incidence in the study sample of 7.6/1000 person-years. Radiological confirmation was reported in 85% (117/137). Hospitalization was reported in 41% (56/137) and antibiotic therapy in 93% (127/137) of cases. Using logistic regression modelling, statistically significant associations with pneumonia were a reported history of either asthma, bronchitis or other lung problems and health problems affecting other systems. In most cases, the diagnosis of asthma preceded the diagnosis of pneumonia. The community incidence of all causes of pneumonia is not well enumerated, either in adults or in children. This study provides community-based incidence data. The incidence of hospitalization for pneumonia in this study is comparable to estimates from studies in comparable populations, suggesting that retrospective parental report for memorable events is likely to be valid. We found a relationship between pneumonia and childhood respiratory diseases such as asthma, which has implications for targeted vaccination strategies.

Adolescent↗
PubMed2003

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.

Australia↗
PubMed2002

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.

Adolescent↗
PubMed2002

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.

Adolescent↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Australia↗
PubMed2000

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.

Adolescent↗
PubMed2000

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.

Australia↗
PubMed2000

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.

Adult↗