Diana Lennon

Household crowding a major risk factor for epidemic meningococcal disease in Auckland children.

Background. New Zealand is in its ninth year of a serogroup B meningococcal disease epidemic with annual rates of up to 16.9 cases per 100 000. The highest incidence is in Maori and Pacific Island children in the Auckland region. We conducted a case-control study to identify potentially modifiable risk factors for this disease. Methods. A case-control study of 202 cases of confirmed and probable meningococcal disease in Auckland children younger than 8 years of age recruited from May, 1997, to March, 1999, was undertaken. Controls (313) were recruited door-to-door by a cluster sampling method based on starting points randomly distributed in the Auckland region. They were frequency matched with the expected distribution of age and ethnicity in the meningococcal disease cases. Results. With the use of a multivariate model and controlling for age, ethnicity, season and socioeconomic factors, risk of disease was strongly associated with overcrowding as measured by the number of adolescent and adult (10 years or older) household members per room [odds ratio (OR), 10.7; 95% confidence interval (CI), 3.9 to 29.5]. This would result in a doubling of risk with the addition of 2 adolescents or adults to a 6-room house. Risk of disease was also associated with analgesic use by the child, which was thought to be a marker of recent illness (OR 2.4, CI 1.5 to 4.0); number of days at substantial social gatherings (10 or more people for > 4 h; OR 1.8, CI 1.2 to 2.6); number of smokers in the household (OR 1.4, CI 1.0 to 1.8); sharing an item of food, drink or a pacifier (OR 1.6, CI 1.0 to 2.7); and preceding symptoms of a respiratory infection (cough, “cold or flu,” runny nose, sneezing) in a household member (OR 1.5, CI 1.0 to 2.5). Conclusion. Some of these identified risk factors for meningococcal disease are modifiable. Measures to reduce overcrowding could have a marked effect on reducing the incidence of this disease in Auckland children.

New Zealand Epidemic of Meningococcal Disease Identified by a Strain with Phenotype B:4:P1.4

New Zealand is experiencing an epidemic of serogroup B meningococcal disease, which has taken the rate of disease from an average of 1.5/100,000 population in the preepidemic years of 1989 and 1990 to 14.0/100,000 in 1996. Sterile-site isolates of Neisseria meningitidis from cases of invasive disease have been phenotypically characterized by serogrouping, serotyping, and serosubtyping, revealing the involvement of a strain with phenotype B:4:P1.4. Macrorestriction analysis using pulsed-field gel electrophoresis on 667 meningococci isolated from cases during the epidemic has identified the clonal relationship of meningococci expressing the PorA P1.4 antigen. Multilocus enzyme electrophoresis has shown the epidemic strain B:4:P1.4 to belong to lineage III. The recorded characteristics of New Zealands epidemic are consistent with previous serogroup B epidemics in other parts of the world.

Epidemic perinatal listeriosis

During the 11 months beginning in January, 1980, 22 cases of perinatal Listeria monocytogenes infection occurred at three obstetric hospitals in Auckland, New Zealand. Most cases were due to type lb strains. Since the previous epidemic here in 1969, about one perinatal infection has been diagnosed annually in the same area. Women presented in preterm (11 of 22 cases) or term labor with signs of amnionitis (11 of 22 cases) and associated fetal distress and/or meconium-stained liquor (14 of 19 cases). A mild “flu”-like illness or urinary tract symptoms were common (18 of 22 women). Five fetal deaths occurred. Three were before 20 weeks of gestation. Most liveborn affected babies had early respiratory symptoms (12 of 14 cases). Meningitis occurred in 4 of 14 infants. There was one death. Vaginal carriage of L. monocytogenes was found in only 1 of 750 consecutive asymptomatic pregnant women who were tested at the time of the epidemic. Rectal carriage was found in 25 (3.3%). Pacific Island Polynesians were rectal carriers of L. monocytogenes and were represented among the epidemic cases more often than expected according to birth data (P < 0.05 and P < 0.001, respectively). The cause of the epidemic was not discovered but shellfish and raw fish consumption may have played a part.

Delayed immunisation and risk of pertussis in infants: unmatched case-control study

Pertussis remains a severe disease in infants. As about two thirds of infants with pertussis are admitted to hospital, factors that seem to be associated with an increased risk of pertussis may in fact be associated with an increased risk of hospital admission. 1 2 The admission rate for pertussis in New Zealand is five to 10 times higher than in England and Wales and the United States.3 We determined whether immunisation reduced the risk of admission to hospital for pertussis by comparing infants admitted with pertussis and infants admitted with other acute respiratory illnesses. View this table: Odds ratios (95% confidence intervals) of catching pertussis associated with delays in giving pertussis vaccine We performed an unmatched case-control study during the 1995-7 pertussis epidemic in Auckland, New Zealand. Pertussis was defined as cough lasting at least two weeks, with coughing paroxysms, inspiratory “whoop,” or vomiting after coughing. The control group consisted of 98 infants admitted to hospital with a coughing illness who were …

Acute rheumatic fever in Auckland, New Zealand: spectrum of associated group A streptococci different from expected.

Annual specific rates for acute rheumatic fever (ARF) in Auckland children less than 15 years were 22/100,000 for the years 1980 to 1984. From 1984 to 1992 the rates remained relatively constant with an average of 45 (range, 30 to 70) children annually admitted with ARF to the Auckland Childrens Hospital. This study examined retrospectively Group A streptococci identified from hospitalized pediatric patients during these 9 years. The total of 2410 isolates included 32 isolates from well-documented cases of ARF and an additional 6 from siblings of cases. Results of M typing indicated that streptococci associated with ARF are generally different from those described overseas and involved types which cause more skin than throat infections in the community.

Once-daily amoxicillin versus twice-daily penicillin V in group A β-haemolytic streptococcal pharyngitis

Background: Rheumatic fever is a preventable chronic disease preceded by group A β-haemolytic streptococcal (GABHS) pharyngitis. Objective: To test the non-inferiority of once-daily (QD) oral amoxicillin to the recommended twice-daily (BID) oral penicillin V in GABHS pharyngitis. Methods: This was a randomised non-inferiority trial carried out in a school-based clinic in New Zealand. Children presenting with GABHS pharyngitis were randomised to oral amoxicillin 1500 mg QD (or 750 mg if bodyweight was ⩽30 kg) or to oral penicillin V 500 mg BID (or 250 mg if bodyweight was ⩽20 kg) for 10 days. Observed medication and weekend diary cards were used to monitor adherence. Outcome: Eradication of GABHS, determined with follow-up throat cultures on days 3–6, 12–16 and 26–36. GABHS isolates were serotyped to distinguish bacteriological treatment failures (and relapses) from new acquisitions. Non-inferiority was defined as an upper 95% confidence limit (CL) for the difference in success of eradication in the amoxicillin and penicillin V treatment groups of ⩽10%. Results: 353 children with positive throat swabs for GABHS were randomised to amoxicillin (n = 177) or penicillin V (n = 176). The upper 95% CL for the differences in positive cultures between the antibiotics was 4.9% at days 3–6, 6.5% at days 12–16 and 8.5% at days 26–36. Treatment failures (including relapses) occurred at each visit in 5.8%, 12.7% and 10.7% of amoxicillin recipients and 6.2%, 11.9% and 11.3% of penicillin V recipients, respectively. No significant differences in resolution of symptoms were noted between treatment groups. One case of unsubstantiated acute rheumatic fever occurred after 7 days of amoxicillin. Conclusion: In this adequately powered study, once-daily oral amoxicillin is not inferior to twice-daily penicillin V for the treatment and eradication of GABHS in children with pharyngitis.

Invasive pneumococcal disease in a pediatric population, Auckland, New Zealand

Streptococcus pneumoniae is one of the major invasive pathogens in childhood. The increasing worldwide prevalence of penicillin-resistant strains makes management of invasive infections difficult and underscores the need for effective vaccines. Currently avaialable vaccines are of limited value in the pediatric age group. Trials are taking place to evaluate conjugated pneumococcal vaccines and in view of this it is important to establish local epidemiology of pneumococcal disease. The aims of this population-based study were to review all of the cases of invasive pneumococcal disease occurring during a 9-year period (1984 to 1992) in Auckland, New Zealand. Through the use of laboratory records and hospital discharge codes, 413 isolates from 407 patients were found. Age-specific incidence for all invasive disease was 22.0/100 000 for children less than 15 years old but 56.0/100 000 for children less than 5 years old (X2 Yates corrected 18.20; P = 0.001). Two-thirds were less than 2 years old. The rates were higher in Maori and Pacific Island children than in Caucasian children. A total of 70 isolates from 68 patients with meningitis occurred. The majority were less than 5 years old (incidence of meningitis was 10.0/100 000) and 84% were less than 2 years old. The overall mortality from meningitis was 4.3%. Of the 129 isolates serogrouped or serotyped, 14, 6 and 19 accounted for 23%, 16% and 16%, respectively, of cases. Although 98% of serotypes identified would be covered by the currently available 23-valent vaccine, two-thirds of the children affected by these isolates would be unprotected because of poor immunogenicity of polysaccharide vaccines in children less than 2 years old.

Incidence, Risk Factors, and Outcomes of Panton-Valentine Leukocidin-Positive Methicillin-Susceptible Staphylococcus aureus Infections in Auckland, New Zealand

ABSTRACT Panton-Valentine leukocidin (PVL) has been linked to invasive community-acquired methicillin-resistant Staphylococcus aureus infections. However, the association between disease and PVL-positive methicillin-susceptible Staphylococcus aureus (MSSA) has not been widely reported. We aimed to examine the epidemiology of PVL in clinical MSSA isolates from patients presenting to Auckland City Hospital. Four hundred eleven MSSA clinical isolates and 93 nasal carriage isolates were collected and tested for the presence of the lukSF-PV genes using PCR. The results were examined in light of host and disease factors. Multilocus sequence typing (MLST) was performed on a random subset of isolates to ensure that there was no single PVL-positive MSSA clone responsible for disease in Auckland. The prevalence of the lukSF-PV genes in MSSA isolates associated with disease (124/335; 37%) was not significantly different from the prevalence of the lukSF-PV genes in MSSA nasal carriage isolates (29/93; 31% [P = 0.33]). PVL-positive MSSA isolates in Auckland are genetically diverse and come from a number of different clonal complexes. PVL-positive infections peaked at between 10 and 20 years of age, with a subsequent decline. Pacific ethnicity, age, diagnosis of skin and soft tissue infection (SSTI), community-onset infection, and the need for surgical intervention were found by multivariate analysis to be independently associated with PVL-positive MSSA infection. More than one-third of MSSA infections in our patient population are caused by PVL-positive strains. Those patients with PVL-positive MSSA infection were more likely to be of Pacific ethnicity, be younger in age, have community-onset infection, have SSTI, and need surgical intervention.

School-based prevention of acute rheumatic fever: a group randomized trial in New Zealand.

Background: Acute rheumatic fever (ARF) and its sequela, rheumatic heart disease is the commonest cause of childhood cardiac morbidity globally. The current approach to the prevention of a primary attack of rheumatic fever in children using oral medication for streptococcal pharyngitis is poorly supported. The efficacy of injectable penicillin, in high rheumatic fever incidence military environments is indisputable. Objective: To evaluate school-based control of rheumatic fever in an endemic area. Methods: Fifty-three schools (∼22,000 students) from a rheumatic fever high incidence setting (∼60/100,000) in Auckland, New Zealand were randomized. The control group received routine general practice care. The intervention was a school-based sore throat clinic program with free nurse-observed oral penicillin treatment of group A streptococcal pharyngitis. The outcome measure was ARF in any child attending a study school. Analysis A defined ARF cases using criteria derived from Jones Criteria 1965 (definite) and 1956 (probable) with more precise definitions. Analysis B was based on 1992 Jones criteria but also included echocardiography to determine definite cases. Results: In Analysis A, 24 (55/100,000) cases occurred in clinic schools and 29 (67/100,000) in nonclinic schools, a 21% reduction when adjusted for demography and study design (P = 0.47). Analysis B revealed a 28% reduction 26 (59/100,000) and 33 (77/100,000) cases, respectively (P = 0.27). Conclusion: This study involving 86,874 person-years showed a nonsignificant reduction in the school-based sore throat clinic programs.

New Zealand epidemic strain meningococcal B outer membrane vesicle vaccine in children aged 16-24 months

Background: New Zealand has experienced an epidemic of Neisseria meningitidis dominated by strain B:4:P1.7b,4 since 1991. Children younger than 5 years are at highest risk. Previous serogroup B outer membrane vesicle (OMV) strain specific vaccines have shown variable efficacy in this age group. Objective: To evaluate the immunogenicity, reactogenicity and safety in 16–24-month-old children of an OMV vaccine developed against the New Zealand epidemic strain. Methods: Children (332) aged 16–24 months were randomized to receive the New Zealand candidate vaccine made using strain NZ98/254 (B:4:P1.7b,4) or the Norwegian parent vaccine made using strain 44/76 (B:15:P1.7,16). Vaccines (25 μg/dose) were administered at 0, 6 and 12 weeks in this observer-blind trial. Immune response was measured by serum bactericidal assay and enzyme-linked immunosorbent assay. Sero-response was defined as a 4-fold or greater rise in serum bactericidal antibody titer compared with baseline, with titers <1:4 required to increase to ≥1:8 to be considered a sero-response. Local and systemic reactions were monitored for 7 days after vaccination. Results: Sero-response against NZ98/254 was achieved after 3 doses in 75% (95% CI: 69–80%) receiving the New Zealand candidate vaccine by both intention to treat (ITT) and per protocol (PP) analyses. In Norwegian parent vaccinees this was seen in 3% (0–12%) (ITT) and 4% (0–13%) (PP). Vaccines were well tolerated with no vaccine-related serious adverse events. Conclusion: The New Zealand candidate vaccine administered to these 16–24-month-old children in 3 doses was safe and elicited a promising immune response against the candidate vaccine strain NZ98/254 (N. meningitidis B:4:P1.7b,4) contributing to vaccine licensure for this age group.