The immunogenicity and tissue reactivity of Mycobacterium avium subsp paratuberculosis inactivated whole cell vaccine is dependent on the adjuvant used

Johne's disease (JD) is a chronic enteritis caused by Mycobacterium avium subspecies paratuberculosis (MAP). Current commercial vaccines are effective in reducing the occurrence of clinical disease although vaccinated animals can still become infected and transmit MAP. Many vaccinated sheep develop severe injection site lesions. In this study a range of adjuvants (Montanide^TM ISA 50V, ISA 50V2, ISA 61VG, ISA 70 M VG, ISA 71 VG, ISA 201 VG and Gel 01 PR) formulated with heat-killed MAP were tested to determine the incidence of injection site lesions and the types of immune profiles generated in sheep. All the novel formulations produced fewer injection site lesions than a commercial vaccine (Gudair®). The immune profiles of the sheep differed between treatment groups, with the strength of the antibody and cell mediated immune responses being dependant on the adjuvant used. One of the novel vaccines resulted in a reduced IFN-γ immune response when a second “booster” dose was administered. These findings have significance for JD vaccine development because it may be possible to uncouple protective immunity from excessive tissue reactivity, and apparently poorly immunogenic antigens may be re-examined to determine if an appropriate immune profile can be established using different adjuvants. It may also be possible to formulate vaccines that produce targeted immunological profiles suited to protection against other pathogens, i.e. those for which a bias towards cellular or humoral immunity would be advantageous based on understanding of pathogenesis.

Sheep and cattle exposed to Mycobacterium avium subspecies paratuberculosis exhibit altered total serum cholesterol profiles during the early stages of infection

Pathogenic mycobacteria such as Mycobacterium tuberculosis are capable of utilising cholesterol as a primary carbon-based energy source in vitro but there has been little research examining the significance of cholesterol in vivo. Johne's disease is a chronic enteric disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). This study sought to evaluate the levels of total serum cholesterol in the host following exposure to MAP. Blood samples were collected from both sheep and cattle prior to experimental challenge with MAP and at monthly intervals post-challenge. Total serum cholesterol levels in sheep challenged with MAP were significantly elevated at 9 weeks post-inoculation (wpi) in comparison to controls. When stratified based on disease outcome, there was no significant difference in serum cholesterol at the timepoints examined between MAP exposed sheep that were susceptible and those that were resistant to Johne's disease. There was a similar elevation in serum cholesterol at 9 wpi in cattle with histopathological gut lesions associated with disease or those with an early high IFN-γ response. Total serum cholesterol in exposed cattle was significantly lower when compared to controls at 13 wpi. Taken together, these results demonstrate changes in serum cholesterol following MAP exposure and disease progression which could reflect novel aspects of the pathogenesis and immune response associated with MAP infection in both sheep and cattle.

Variation in susceptibility of different breeds of sheep to Mycobacterium avium subspecies paratuberculosis following experimental inoculation

Exposure to Mycobacterium avium subspecies paratuberculosis (MAP) does not always lead to Johne’s disease. Understanding differences in disease susceptibility of individual animals is a key aspect to controlling mycobacterial diseases. This study was designed to examine the susceptibility or resistance of various breeds of sheep to MAP infection. Merino, Suffolk first cross Merino, Border Leicester, and Poll Dorset sheep were orally inoculated with MAP and monitored for 14 months. Clinical disease occurred more frequently in the Merino (42%) and Suffolk first cross Merino (36%) compared to the Border Leicester (12%) and Poll Dorset (11%) breeds. Infection risk, as determined by culture of gut and associated lymphoid tissues, ranged from 75% for the Suffolk first cross Merino to 47% for the Poll Dorset sheep. Significant differences were identified in the site in the intestines of the most severe histopathological lesions and the immune responses to infection between the breeds. However, there was no difference in faecal MAP shedding by clinical cases between breeds. All breeds tested were susceptible to MAP infection, as determined by infection and clinical disease development, although there were differences in the proportions of diseased animals between the breeds. Poll Dorset and Border Leicester sheep were more resilient to MAP infection but there was evidence that more animals could have developed disease if given more time. These findings provide evidence of potential differential disease susceptibility between breeds, further our understanding of disease pathogenesis and risks of disease spread, and may have an influence on control programs for paratuberculosis.

Development of 316v antibody enzyme-linked immunosorbent assay for detection of paratuberculosis in sheep

An enzyme-linked immunosorbent assay (ELISA) was developed and optimised using a Mycobacterium avium subspecies paratuberculosis (MAP) antigen prepared from a C strain (316v) passed through a French press. The optimised assay was evaluated with a panel of sera from MAP infected (n = 66) and uninfected (n = 1,092) sheep. Animals in the MAP infected category were positive on either tissue culture or histopathology but were of unknown serum antibody status. The diagnostic performance and cost of the assay were compared with those of a commercial ELISA (IDEXX). At 99.8% diagnostic specificity the assay showed a diagnostic sensitivity of 23% (95% CI: 15.1-35.8) compared with 36.4% (95% CI: 25.8-48.4) for the commercial ELISA (McNemar's test: chi-square 5.82, p < 0.05). The sensitivities were 5.9% (95% CI: 1-26.9), 27.9% (95% CI: 14.7-45.7) and 35% (95% CI: 18.1-56.7), for low grade, paucibacillary and multibacillary lesion grades, respectively. The cost of the commercial assay kit was 2.7 to 5.2 times greater than that of the 316v ELISA for an equivalent number of tests, the multiple depending on the number of plates processed per run. For flock-level surveillance, to account for the lower sensitivity of the 316v ELISA compared with the commercial ELISA, sample sizes would be increased but the test cost would still be lower. The 316v assay will be useful for diagnosis of Johne's disease in sheep flocks, particularly in developing countries where labour costs are low relative to the cost of consumables.

Pre-licensed driving experience and car crash involvement during the learner and restricted, licence stages of graduated driver licensing: Findings from the New Zealand drivers study

OBJECTIVE

The aim of this study was to determine whether pre-licence driving experiences, that is driving before beginning the licensing process, increased or decreased crash risk as a car driver, during the learner or the restricted licence stages of the graduated driver licensing system (GDLS).

METHOD

Study participants were 15-24 year old members of the New Zealand Drivers Study (NZDS) - a prospective cohort study of newly licensed car drivers. The interview stages of the NZDS are linked to, the three licensing stages of the GDLS: learner, restricted and full. Baseline demographic (age, ethnicity, residential location, deprivation), personality (impulsivity, sensation seeking, aggression) and, behavioural data, (including pre-licensed driving behaviour), were obtained at the learner licence interview. Data on distance driven and crashes that occurred at the learner licence and restricted licence stages, were reported at the restricted and full licence interviews, respectively. Crash data were also obtained from police traffic crash report files and this was combined with the self-reported crash data. The analysis of the learner licence stage crashes, when only supervised driving is allowed, was based on the participants who had passed the restricted licence test and undertaken the NZDS, restricted licence interview (n=2358). The analysis of the restricted licence stage crashes, when unsupervised driving is first allowed, was based on those who had passed the full licence test and completed the full licence interview (n=1428).

RESULTS

After controlling for a range of demographic, personality, behavioural variables and distance driven, Poisson regression showed that the only pre-licence driving behaviour that showed a consistent relationship with subsequent crashes was on-road car driving which was associated with an increased risk of being the driver in a car crash during the learner licence period.

CONCLUSION

This research showed that pre-licensed driving did not reduce crash risk among learner or restricted licensed drivers, and in some cases (such as on-road car driving) may have increased risk. Young people should be discouraged from the illegal behaviour of driving a car on-road before licensing.

Validity of using linked hospital and police traffic crash records to analyse motorcycle injury crash characteristics

Linking hospital discharge and police traffic crash records has been used to provide information on causes and outcomes for hospitalised traffic crash cases. Motorcyclists are particularly vulnerable to injury in a traffic crash, but no published linkage studies have reported in detail on this road user group. The present study examined motorcycle traffic crash injury cases in New Zealand in 2000-2004 by probabilistically linking national hospital discharge records with police traffic crash reports. Injury cases had to have spent at least one night in hospital before being discharged and were defined as serious or moderate based on their International Classification of Disease Injury Severity Scores (ICISS). Despite a robust linkage process, only 46% of cases could be linked to a police record; 60% of the serious injuries and 41% of the moderate. The low linkage was most likely due to under-reporting of crashes to or by the police. While moderate injury cases were expected to be under-reported, the level of under-reporting of cases with serious threat-to-life injuries is concerning. To assess whether the linked dataset could provide valid information on the crash circumstances and injury outcomes of hospitalised motorcycle crash cases, the characteristics of the linked and unlinked hospital discharge cases were compared using chi-square tests and multivariate logistic regression. Serious injury cases were less likely to be linked if only one vehicle was involved, or the injured riders and passengers were younger than 20 years or spent less than one week in hospital. For moderate injury cases, there were also differences in linkage by injured body region and crash month. While these discrepancies need to taken into consideration when interpreting results, the linked hospital-police dataset has the potential to provide insights into motorcycle crash circumstances and outcomes not otherwise obtainable.

Age, period and cohort effects on the incidence of motorcyclist casualties in traffic crashes

Objectives

(1) Estimate age, period and cohort effects for motorcyclist traffic casualties 1979–2008 in New Zealand and (2) forecast the incidence of New Zealand motorcycle traffic casualties for the period 2019–2023 assuming future age, cohort and period effects, and compare these with an estimate based on simple linear extrapolation.

Methods

Age-period-cohort (APC) modelling was used to estimate the individual effects of age, period and cohort after adjusting for the other two factors. Forecasting was produced for three period-effect scenarios.

Results

After adjusting for cohort and period effects, 15–19-year-olds have substantially elevated risk. The period effect reduced in significance over time until the last period, 2004–2008, where the risk was higher than the preceding period. The 10-year cohorts born 1949–1958, 1954–1963, 1959–1968 and 1964–1973, had elevated risk. The forecasting, based on APC modelling, resulted in the lowest estimates of the future incidence being approximately one-third that of the highest estimate (6641).

Conclusion

Trends in motorcycle casualties have been influenced by significant independent age, period and cohort effects. These need to be considered in forecasting future casualties. The selection of the period effect has a significant impact on the estimates. Which period-effect scenario readers choose to accept depends on their views about a wide range of factors which might influence motorcycle use and crash risk over time.

Does a Th1 over Th2 dominancy really exist in the early stages of Mycobacterium avium subspecies paratuberculosis infections?

The immune response of ruminants to Johne's disease has been long associated with a cell mediated immune (CMI) response in the early stages of infection with a switch to an antibody response later as the disease manifests. This study examines the immune response in sheep to Mycobacterium avium subspecies paratuberculosis (Map) infections, specifically the antigen-specific interferon gamma (IFN-γ) and antibody responses as surrogates of T helper-1 (Th1) and Th2 immunity. The difference in IFN-γ production between paucibacillary and multibacillary diseased animals was also examined. The results show that sheep are more likely to have a combined antibody and IFN-γ response (seen in 50% of the animals) rather than a switch from an IFN-γ to antibody response (39%). Multibacillary diseased animals were found to have a decrease in functional ability to produce IFN-γ from cells stimulated with MAP-specific antigens and non-specific mitogens. This indicates that the immune responses to Map infections are more complex than thought, where both antibody and cellular immunity may play key roles in the early stages of disease manifestation or resistance. The loss of the cellular response in multibacillary animals may be an indication that the entire immune response is dysfunctional, with the cell mediated responses becoming affected first.

A longitudinal examination of the relationship between adolescent problem behaviors and traffic crash involvement during young adulthood

Previous research examining the relationship between adolescent problem behaviors and young adult traffic outcomes (crashes, convictions, risky driving) has produced differing results. Possible reasons for this may be the heterogeneity of the crash outcomes (from minor fender-benders to fatal crashes), the gender of the driver, and/or the age of the driver. The aim of this research was to investigate the relationship between adolescent problem behaviors and young adult crashes to determine the extent to which the above factors influenced this relationship. This study was part of the Dunedin Multidisciplinary Health and Development Study (DMHDS), which is a longitudinal study of a cohort (n = 1,037) born in Dunedin, New Zealand, from April 1972 to March 1973. This cohort has been followed up regularly since birth, and the data for the present research were obtained at the 18-, 21-, and 26-year-old follow-up interviews. The problem behaviors examined were those identified by Jessor in the theory of problem behavior, namely, tobacco smoking, marijuana use, alcohol use, delinquent behavior, and unsafe sexual behavior. Data for these measures were obtained in personal interviews when the cohort was aged 18 years. The self-reported crash data were obtained at the age 21 and age 26 follow-up interviews. Driving exposure, academic qualifications, employment, being a parent, and marital status were included as potential confounders. The results show that involvement in adolescent problem behaviors predicted crash involvement at age 21 for the females but not the males and at age 26 for the males but not the females. Possible explanations for these differences by age and gender are discussed.

Minimum purchasing age for alcohol and traffic crash injuries among 15- to 19-year-olds in New Zealand

OBJECTIVES

In 1999, New Zealand lowered the minimum purchasing age for alcohol from 20 to 18 years. We tested the hypothesis that this increased traffic crash injuries among 15- to 19-year-olds.

METHODS

Poisson regression was used to compute incidence rate ratios for the after to before incidence of alcohol-involved crashes and hospitalized injuries among 18- to 19-year-olds and 15- to 17-year-olds (20- to 24-year-olds were the reference).

RESULTS

Among young men, the ratio of the alcohol-involved crash rate after the law change to the period before was 12% larger (95% confidence interval [CI]=1.00, 1.25) for 18- to 19-year-olds and 14% larger (95% CI=1.01, 1.30) for 15- to 17-year-olds, relative to 20- to 24-year-olds. Among young women, the equivalent ratios were 51% larger (95% CI=1.17, 1.94) for 18- to 19-year-olds and 24% larger (95% CI=0.96, 1.59) for 15- to 17-year-olds. A similar pattern was observed for hospitalized injuries.

CONCLUSIONS

Significantly more alcohol-involved crashes occurred among 15-to 19-year-olds than would have occurred had the purchase age not been reduced to 18 years. The effect size for 18- to 19-year-olds is remarkable given the legal exceptions to the pre-1999 law and its poor enforcement.

Vaccination of sheep against M. paratuberculosis: immune parameters and protective efficacy

Johne's disease in ruminants is caused by the pathogenic bacterium Mycobacterium avium subspecies paratuberculosis (Map). Currently available Map commercial vaccines protect against clinical disease but not infection. In this study, the proprietary Johne's vaccine Neoparasec and an aqueous formulation of Map 316F (AquaVax) were tested in sheep. Detailed immunological examination of blood and gut-associated lymphoid tissues was carried out on animals after vaccination and challenge with virulent Map to identify markers of protective immunity. Neoparasec vaccination provided significant protection against disease while AquaVax did not. Immune animals had stronger cell-mediated responses and altered proportions of CD4+, CD8+, CD25+ and B cells in blood, spleen and the gut lymphatics, than diseased animals.

Experimental infection model for Johne's disease in sheep

Johne's disease in ruminants results in chronic enteritis caused by the pathogenic bacterium Mycobacterium avium subsp. paratuberculosis. This study examined two M. avium subsp. paratuberculosis strains (JD3 and W), using different doses and routes of infection, to establish the optimal time postchallenge when predictable levels of infection, gut lesions, and clinical disease occur in a large proportion of sheep. While a small proportion (25%) of sheep challenged with a low-passage-number laboratory culture of M. avium subsp. paratuberculosis (strain W) became infected, no infection was found in animals exposed to a high-passage-number culture isolate of strain W. In contrast, a primary tissue homogenate of M. avium subsp. paratuberculosis (JD3) resulted in high (90%) infection rates and gut histopathology following oral or intratonsillar challenge. The optimal conditions necessary to produce Johne's disease involve oral inoculation of 3-month-old lambs with four doses of 5 x 10(8) CFU of M. avium subsp. paratuberculosis isolated directly from the gut lymphatic tissues of clinically affected sheep. This resulted in consistent gut histopathology at 9 months and the onset of clinical disease by 11 months postchallenge.

Identifying predictors of persistent non-alcohol or drug-related risky driving behaviours among a cohort of young adults

This study sought to identify adolescent risk factors that predicted persistent risky driving behaviours among young adults. It was part of a longitudinal study of a birth cohort (474 males and 459 females). The potential predictors were self-reported data obtained at ages 15, 18, 21 years (academic qualifications, personality, mental health, anti-social behaviour and driving behaviour). The risky driving behaviour outcomes were obtained at ages 21 and 26 years and included driving fast for thrills, taking deliberate risks for fun, excessive speed, dangerous overtaking, and close following (tailgating). Persistent risky drivers were defined as those who often, or fairly often engaged in a behaviour at both ages. A minority of males and very few females were classified as persistent risky drivers. Among the males, the factors that predicted at least one, or more of the outcomes were the personality trait of low constraint (i.e. low scores for control, harm avoidance, and traditionalism), aggressive behaviour, and cannabis dependence. These are characteristics to be borne in mind when developing programmes for young drivers that aim to deter the development of persistent risky driving behaviour.

Identifying factors that predict persistent driving after drinking, unsafe driving after drinking, and driving after using cannabis among young adults

The main aim of this study was to identify adolescent/young adulthood factors that predicted persistent driving after drinking, persistent unsafe driving after drinking, and persistent cannabis use and driving among young adults. It was a longitudinal study of a birth cohort (n=933, 474 males and 459 females) and was based on data collected at ages 15, 18, 21 and 26 years. At each of these ages members of the cohort attended the research unit for a personal interview by a trained interviewer, using a standardised questionnaire. For this study, the data for the outcome measures (persistent driving after drinking, persistent unsafe driving after drinking, and persistent driving after using cannabis) were obtained at ages 21 and 26 years. The main explanatory measures were collected at ages 15, 18, 21 years and included demographic factors (academic qualifications, employment, parenting); personality measures; mental health measures (substance use, cannabis dependence, alcohol dependence, depression); anti-social behaviour (juvenile arrest, aggressive behaviour, court convictions); early driving behaviour and experiences (car and motorcycle licences, traffic crashes). The analyses were conducted by gender. The results showed that females who persisted in driving after drinking (13%, n=61) were more likely than the others to have a motorcycle licence at 18. The males who persisted in driving after drinking (28%, n=135) were more likely than the other males to have some school academic qualifications and to be employed at age 26. Compared to the other males, those who persisted in unsafe driving after drinking (4%, n=17) were more likely to be aggressive at 18 and alcohol dependent at 21. Only six (1%) females persisted in unsafe driving after drinking so regression analyses were not conducted for this group. For persistent driving after using cannabis, the univariate analyses showed that females who persisted with this behaviour tended to have high substance use at 18, cannabis dependence at 21, police contact as a juvenile, and to be a parent at 21. For this group, because of the small numbers (3%, n=13) multivariate analyses were not appropriate. For the males who persisted in driving after using cannabis (14%, n=68) a wide range of variables were significant at the univariate stage. The multivariate analysis showed that the most important factors were dependence on cannabis at 21, at least one traffic conviction before 21, a non traffic conviction before 18, and low constraint at 18.

CONCLUSION

These results show different characteristics were associated with persistence in each of these outcome behaviours. This indicates that different approaches would be required if intervention programmes were to be developed to target these behaviours.

Personal and situational influences on drink driving and sober driving among a cohort of young adults

OBJECTIVES

To compare personal and situational influences on incidents involving drink driving with those involving sober driving.

METHODS

Information on a range of road safety practices was sought in face to face interviews conducted with 969 members of the Dunedin Multidisciplinary Health and Development Study cohort at age 26 years. A total of 750 study members reported an incident that involved the opportunity to consume alcohol and also travel by motor vehicle. Of these, 87 were classified as "drink drive incidents" and 663 as "sober drive incidents".

RESULTS

Study members who were male, of lower socioeconomic status, had no school qualifications, or were dependent on alcohol or marijuana at age 21 were significantly more likely to report a drink drive incident at age 26. Compared with the sober drive incidents, the drink drive incidents were more commonly associated with driving alone, drinking at bars, and no advanced planning. For drink drive incidents the amount of alcohol consumed was influenced by the conviviality of the occasion, whereas for sober drive incidents it was the need to drive. One quarter of those reporting drink drive incidents stated they had used marijuana and/or LSD at the event at which they drank.

CONCLUSIONS

Drink drive and sober drive incidents differed, particularly with regard to decisions made before the event. Prevention efforts could usefully be targeted toward these decisions.

Impact of graduated driver licensing restrictions on crashes involving young drivers in New Zealand

OBJECTIVE

To determine the impact on young driver crashes of the three main driving restrictions in the New Zealand graduated driver licensing (GDL) system: night-time curfew, no carrying of young passengers, and a blood alcohol limit of 30 mg/100 ml.

METHOD

The database for this study was created by linking police crash reports to hospital inpatient records (1980-95). Multivariate logistic regression was used to compare car crashes involving a young driver licensed before GDL (n=2,252) with those who held a restricted graduated licence (n=980) and with those who held a full graduated licence (n=1,273), for each of the main driving restrictions.

RESULTS

Compared with the pre-GDL group, the restricted licence drivers had fewer crashes at night (p=0.003), fewer involving passengers of all ages (p=0.018), and fewer where alcohol was suspected (p=0.034), but not fewer involving young casualties (p=0.980). Compared with the pre-GDL drivers, those with the full graduated licence had fewer night crashes (p=0.042) but did not differ significantly for any of the other factors examined.

CONCLUSION

These results suggest that some of the GDL restrictions, especially the night-time curfew, have contributed to a reduction in serious crashes involving young drivers.

Validity of self reported crashes and injuries in a longitudinal study of young adults

OBJECTIVES

The aim of this study was to determine the validity of self report as a source of information on crashes and injuries.

SETTING

This study was part of the Dunedin Multidisciplinary Health and Development Study (DMHDS), which is a longitudinal study of the health, development, and behaviour of a cohort of young New Zealanders.

METHOD

At the age 21 assessment DMHDS study members were asked to report serious injury and motor vehicle traffic crashes experienced over the previous three years. The self reported injuries were compared with the New Zealand Health Information Service (NZHIS) public hospital discharge file to determine the completeness of the self reported data. The traffic crashes were compared with the police traffic crash reports to determine the accuracy of self reported crash details.

RESULTS

Twenty five (86%) of the 29 unintentional injuries, six (67%) of the nine assaults, and one (14%) of the six self inflicted injuries on the NZHIS file were self reported. The level of agreement between the self reported crash details and those recorded on the traffic crash report was high.

CONCLUSIONS

The results show that self reports can be a useful and valid source of injury and crash data.

Road traffic practices among a cohort of young adults in New Zealand

AIM

To describe the road safety practices of young adults in New Zealand.

METHOD

Face to face structured interviews, seeking information on a range of road safety practices, were conducted with 948 members of the Dunedin Multidisciplinary Health and Development Study cohort when they were 21 years old.

RESULTS

In the 30 days before the interview, 49% of the males and 32% of the females reported driving within two hours of drinking alcohol; 19% males and 8% females reported driving after drinking too much to perhaps be able to drive safely: and 25% males and 9% females reported driving after using marijuana. Also, 25% males and 6% females reported that they "often" drove fast just for the thrill of it, and 38% males and 11% females reported "often" driving faster than 120 kph on the open road. Seatbelt use as a driver was reported as "always" or "nearly always" by 87% of the males and 95% of the females, but as a rear seat passenger it was 34% for males and 47% for females.

CONCLUSIONS

Unsafe road traffic practices, especially among males, were unacceptably high. Continued efforts are required to find new ways of addressing these issues.

A longitudinal study of lifestyle factors as predictors of injuries and crashes among young adults

This study was part of the Dunedin Multidisciplinary Health and Development Study. This is a longitudinal study of the health, development and behaviour of a cohort of 1037 young people born in Dunedin, New Zealand between 1 April 1972 and 31 March 1973. Explanatory measures covering background, behavioural and personality factors were obtained at ages 15 and 18 and were used as potential predictors of outcomes reported at age 21. Four outcomes were considered: any crash, injury crash, non-injury crash, and serious injury (not motor vehicle related). Overall, very few lifestyle factors were important predictors of any of these outcomes. Factors that were shown to predict injury crashes differed from those that predicted non-injury crashes. Also, those that predicted a traffic crash differed from those that predicted a serious non-traffic injury. These results suggest that focusing injury prevention efforts on changing the lifestyles of young adults is unlikely to reduce overall crash risk, and would have little impact on the risk of serious injury.

Inattentive and hyperactive behaviors and driving offenses in adolescence

OBJECTIVE

The associations between symptoms of attention-deficit hyperactivity disorder (ADHD), conduct disorder, anxiety, or depression and no disorder in relation to driving offenses were examined in 916 adolescents.

METHOD

Self-report and parent report were used to assess a birth cohort of New Zealand adolescents' mental health status at age 15 years. Adolescents who scored 1.5 SD above the mean on the DSM-III total ADHD symptom scale were identified as reporting significant ADHD symptomatology. Self-report data and official traffic conviction records were used to identify adolescents who had committed driving offenses between ages 15 and 18 years.

RESULTS

ADHD symptomatology and conduct disorder were strongly associated with driving offenses. ADHD symptomatology in females was significantly associated with driving offenses and more traffic crashes compared with other disorder or no disorder.

CONCLUSIONS

Adolescents with a history of ADHD and conduct problems are significantly more likely than their peers to commit traffic offenses. Research in ADHD and risky driving should include female adolescents, as those with attentional difficulties are at a high risk for being involved in traffic crashes than females who do not experience attentional difficulties.

Sport and delinquency: an examination of the deterrence hypothesis in a longitudinal study

OBJECTIVE

To determine whether involvement in sporting activity in mid-adolescence would deter delinquent behaviour in late adolescence.

METHODS

Members of a longitudinal cohort study were interviewed at ages 15 and 18 years and, among other topics, were asked questions relating to involvement in physical activity and delinquent behaviour. Logistic regression models were used to examine the relation between sports involvement and delinquency at age 15 years and delinquency at age 18.

RESULTS

After controlling for delinquent behaviour and psychosocial factors at age 15, females with moderate or high levels of sporting activity, and males with high levels of sporting activity, were significantly more likely to be delinquent at age 18 years than those with low levels of sporting activity. No significant association was found between sporting activity and aggressive behaviour, team sport participation and delinquency, and team sport participation and aggressive behaviour.

CONCLUSIONS

This study did not support the deterrence hypothesis and showed that high involvement in sporting activity, but not team sport, was associated with a subsequent increase in delinquent behaviour.

An evaluation of the New Zealand graduated driver licensing system

Young drivers have a disproportionately high risk of experiencing a road traffic crash. On 1 August 1987 a Graduated Driver's Licensing System (GDLS) was introduced in New Zealand. This system was designed to give young drivers (i.e. 15-24 years inclusive) experience in driving while being excluded from high risk driving situations. We sought to determine the impact of the GDLS on serious injury crashes. The source of the injury crash data was New Zealand's Health Information Services' national public hospital inpatient morbidity data files for the years 1979-1992 inclusive. We disaggregated the occupant data into three age groups 15-19 years, 20-24 years, and persons 25 years of age or older and compared their trends in injury. In order to determine whether the incidence of motor vehicle crashes was simply following trends in other injury events we also included two 15-19 year old non-traffic injury comparison groups. Using time series analyses we showed that the introduction of the GDLS was closely followed by substantial reductions in car crash injuries for all age groups, especially 15-19 year olds (23% reduction). After considering effects for older occupants we speculate that the effect is likely to be substantially less than 23%. An analysis of licensure data suggests that the reduction in crashes may, in large part, be attributable to an overall reduction in exposure.

The New Zealand graduated driver licensing system: teenagers' attitudes towards and experiences with this car driver licensing system

OBJECTIVES

This study examined the attitudes of teenagers towards the New Zealand graduated driver licensing system (GDLS), and the extent to which it affected them.

METHOD

Teenagers, who are members of a longitudinal study of a birth cohort, were interviewed at 15 years of age when the GDLS was first introduced and before they had begun licensure, and again at 18 years of age after they had experience with this licensing system.

RESULTS

At both ages the majority (over 70%) agreed with the driving restrictions imposed by this system. After experience with the restrictions, however, significantly more reported being affected a lot by them, than had expected to be at age 15. This was especially true of the restrictions on the carrying of passengers and the night time curfew (10 pm - 5 am). However, few reported that they were affected by the alcohol restriction. Sixty eight per cent of those with a graduated licence reported breaking at least one of the conditions, most frequently carrying passengers. Very few were penalised by the police for this.

CONCLUSIONS

Generally these young drivers were positively disposed towards the driving restrictions, but noncompliance was common. A full evaluation of all aspects of this licensing system is recommended.

Motorcycle crashes resulting in death and hospitalisation. II: Traffic crashes

This is the second paper in a series of three that describe the epidemiology of motorcycle crashes in New Zealand that result in death and hospitalisation. The first paper presented an overview of all motorcycle crashes. This paper focuses on traffic crashes. The source of the fatality data was national mortality data files for the years 1978 to 1987 inclusive. The source of the hospitalisation data was the 1988 national morbidity file which records all public hospital discharges in New Zealand. For the period 1978 to 1987, 1,175 fatalities were identified resulting in a mortality rate of 3.5 per 100,000 persons per year. Males aged 15-19 and 20-24 had very high rates (25.2 and 26.4, respectively), especially labourers (40.0) and forestry workers (32). Maori and non-Maori had similar rates. The majority (63%) of the deaths were attributable to a collision with another motor vehicle. During 1988 2,222 motorcyclists were hospitalised giving an incidence rate of 68.1 per 100,000 persons per year. Males aged 15-19 and 20-24 had very high rates (409 and 416, respectively), especially labourers (355). Maori had a higher morbidity rate than non-Maori (99 versus 61). The most common (40%) crash was a collision with another motor vehicle. The most common sites of injury were the lower limb (43%) and head (23%). Collision crashes were more likely to result in lower limb injury, be more severe, and result in longer stays in hospital.

Motorcycle crashes in New Zealand resulting in death and hospitalisation. I: Introduction methods and overview

Relative to car crashes motorcycle crashes have received relatively little attention by the research community. This is the first in a series of three papers describing the epidemiology of motorcycle crashes resulting in death and hospitalisation in New Zealand. This paper describes the methods used for the study, provides an overview of all crashes, and, in particular, compares traffic crashes with nontraffic crashes. The source of the fatality data was national mortality data files for the years 1978 to 1987 inclusive. The source of the hospitalisation data was a national morbidity file, which records all public hospital discharges in New Zealand. A total of 1,175 motorcyclist fatalities were identified for the period 1978-1987, resulting in a mortality rate of 3.6 per 100,000 persons per year. A total of 2,623 motorcycle crash victims were hospitalised in 1988 resulting in a hospitalisation rate of 80.4 per 100,000 persons per year. Males, especially those 15-24 years of age had very high mortality (26-27) and morbidity rates (464-462). Motor vehicle traffic crashes represented 96% of the fatalities and 85% of the hospitalisations. Drivers were the victims in 88% of fatalities and 86% of hospitalisations. For hospitalised victims the leading injuries were to the lower limb (43%) and head (24%). Whereas 29% of the traffic crashes were AIS-3 or higher the comparable figure for nontraffic crashes was 19%. There has been a significant linear increase in the fatality rate between 1978 and 1988 but no comparable trend in hospitalisations.(ABSTRACT TRUNCATED AT 250 WORDS)

Motorcycling attitudes and behaviours. II. 14 and 15 year old adolescents

Of 846 adolescents interviewed near their 15th birthday, 51% could drive a motorcycle. A further 13% intended to learn. Drivers reported friends (mean age 16.5 years) as the most common source of instruction. Forty-four per cent of drivers and 69% of intending learners planned to apply for licences. Thirty-five per cent of the sample had driven or ridden as passengers on a motorcycle on-road in the past year and 85% of these had worn a helmet on the last occasion. The commonest cause of injuries to motorcyclists resulting in hospitalization (lower limb injury) was correctly identified by 52% of the sample. Fear of injury was the reason given for not learning to ride by 55% of confirmed non-drivers. Fifteen medically treated motorcycling injuries were reported for a 2-year recall period. Females reported significantly less exposure and less use of protective clothing than males. The issues of initiation, training, constraints on use and preventive strategies are discussed.

Motor vehicle road crashes during the fourteenth and fifteenth years of life

From a sample of 848 teenagers, 50 individuals reported a total of 52 motor vehicle road crash events: 42 involved a car, six a motorcycle, and four a bus, over a two year period. Males and females were equally represented in each type of crash. Twenty-one of the car crashes, four of the motorcycle crashes and three of the bus crashes involved injury. The injuries sustained in the motorcycle crashes were predominantly to the extremities and in the other crashes they were mainly to the head or face. On average drivers less than 25 years of age had more passengers in their cars and were involved in more nighttime crashes. A seat belt was worn in only 18 (44%) of the car crashes. A motorcycle helmet was worn in four of the six motorcycle crashes. Six (15%) crashes were reported to have involved alcohol. The main areas of risk associated with motor vehicle road crashes involving teenagers and young adults have been addressed by legislation or the graduated drivers' licensing system. An evaluation of these measures is required to establish whether they are effective.

Bicycle road crashes during the fourteenth and fifteenth years of life

From a sample of 848 teenagers 57 individuals reported a total of 62 bicycle road crashes, 40 (65%) of which involved injury to a cyclist. Thirty (48%) of the crashes occurred when the cyclist lost control of the bicycle (73% of which involved injury) and 17 crashes (27%) involved a moving motor vehicle (41% of which involved injury). The majority of the injuries were not serious and of those with multiple injuries no one had an injury severity score greater than five. The body area most frequently injured was the extremities (74%), with the remainder primarily head injuries. Environmental conditions were not a major contributing factor in these crashes. In only five cases the cyclist was wearing a safety helmet. Recommended measures to prevent, or minimise, bicycle related injuries include the wearing of safety helmets, bicycle maintenance checks, and road safety awareness instruction.

Injuries in the 14th and 15th years of life

From a sample of 849 adolescents studied at age 15, 429 had been involved in 657 separate incidents, which resulted in 705 acute injuries requiring medical attention during their 14th and 15th years of life. The most common injuries were sprains, strains, fractures and lacerations, and the most common body site was the finger. The majority of injuries were of minor severity. Striking against an object or person was the most common incident resulting in injury, followed by being struck by an object or person, and overexertion or strenuous movement. Approximately half of the injuries were incurred during sport or a similar physical activity. Sporting injuries are examined in detail and preventive measures discussed.

Road crash experiences during the fourteenth and fifteenth years of life: an overview

From a sample of 848 teenagers, 113 individuals had experienced 121 road traffic crashes. Five of the incidents involved a pedestrian, 62 a bicyclist, six a motor cyclist, 47 a motor vehicle passenger and one a motor vehicle driver. Sixty-two percent of the crashes involved injury and 67% vehicle immobilisation. Five of the injured teenagers were admitted to hospital but the majority (55%) were treated at a hospital accident and emergency department and then discharged. The official reporting of the crashes to the Ministry of Transport was examined and the problems of underreporting and biases in reporting are discussed.