The epidemiology of overweight and obesity among Australian children and adolescents, 1995-97

A study attempts to determine the population prevalence of overweight and obesity among Australian children and adolescents, based on measured body mass index (BMI) to determine if overweight and obesity are distributed differentially across the population of young Australians. Data from three independent surveys were analyzed and results indicate that the population prevalence and distribution of overweight, obesity and overweight/obesity combined were 79%-81%, 14%-16%, 5% and 19%-21% (boys) respectively, and 76%-79%, 16%-18%, 5%-6% and 21%-24% (girls). There were no consistent relationships between the prevalence of overweight/obesity and sex, age or SES. It is concluded that some 19%-23% of Australian children and adolescents are either overweight or obese. Only cultural background differential warrant a targeted health promotion response.

Epidemiology of metabolic syndrome

Metabolic syndrome (MetS), also previously known by a variety of other names, including insulin resistance syndrome and the deadly quartet, is characterized by clustering of abdominal (visceral and retroperitoneal) obesity and other cardiovascular risk factors, including impaired glucose regulation, raised triglycerides, decreased high-density lipoprotein cholesterol (HDL-C), elevated blood pressure (BP).

Associated with increased risk of both type 2 diabetes and cardiovascular disease (CVD), MetS is believed to be a contributor to the modern-day epidemics of diabetes and CVD and has become a major public health challenge around the world [I]. Currently, there are five different sets of criteria which have been developed to characterize the syndrome. These definitions differ in the components included and the cut-points used for each component. The prevalence of MetS in the westernized world is significant (10-50%) and believed to be increasing over time. The pathophysiology of the syndrome is unclear, but it is thought that obesity and/or insulin resistance are key underlying components. Genetics, lifestyle and environment factors are also important causes of MetS.

This chapter provides:

• a historical overview of the evolution of MetS;
• a summary of the value of the different definitions used to characterize the syndrome;
• a summary of the underlying pathophysiology, the causes and other important risk factors of MetS;
• a summary of the evidence describing the association of MetS with CVD and diabetes;
• a summary of the prevalence of MetS using the various definitions in different countries.

Descriptive epidemiology of Australian football injuries presenting to sports medicine clinics

Sports injury prevention has been the focus of a number of recent public health initiatives due to the acknowledgement that sports injuries are a significant public health problem in Australia Whilst Australian football is one of the most popular participation sports in the country, only very limited data is available about football injuries The majority of sports injury data available for this sport is from hospital emergency departments and elite-level injury surveillance Overall there is a paucity of data from treatment settings other than hospitals In particular, there is a lack of information about the injuries sustained by community-level, junior and recreational Australian football participants. One good potential source of football injury data is sports medicine clinics. Analysis of injury presentations to sports medicine clinics was undertaken to provide a detailed description of the epidemiology of Australian football injuries that present to this treatment setting and to determine the implications for injury prevention in this sport. In addition, the data from sports medicine clinics was compared with existing sources of Australian football injury data to determine how representative sports medicine clinic data is of other football injury data sources and to provide recommendations for future injury surveillance n Australian football. The results contained in this thesis show that Australian football is the sport most associated with injury presentation at sports medicine clinics. The majority of injured Australian football players presenting to sports medicine clinics are community-level or junior participants which suggests that sports medicine clinics are a good source of information on the injuries sustained by sub-elite football participants. Competition is the most common context in which Australian football players presenting to sports medicine clinics are injured. The major causes of injuries to Australian football players are being struck by another player, collisions and overuse. Injuries to Australian football players predominantly involve the lower limb. Adult players, players who stopped participating immediately after noticing their injury and players with overuse injuries are the most likely to sustain a more severe injury (i.e. more than four weeks before a full return to football participation and a moderate/significant amount of treatment expected). The least experienced players (five or less years of participation) are more likely to require a significant amount of treatment than the more experienced players. The prevention of lower limb injuries, injuries caused by body contact and injuries caused by overuse should be a priority for injury prevention research in Australian football due to the predominance of these injury types in the pattern of Australian football injuries Additionally, adult players, as a group, should be a focus of injury prevention activities in Australian football due to the association between age and injury severity. Overall, the pattern of Australian football injuries presenting to sports medicine clinics appears to be different than reported by club-based and hospital emergency department injury surveillance activities. However, detailed comparison of sports medicine clinic Australian football data with other sources of Australian football injury data is difficult due to the variable methods of collecting and reporting injury information used by hospital emergency department and club-based injury surveillance activities. The development of a standardised method for collecting and reporting injury data in Australian football is strongly recommended to overcome the existing limitations of data collection in this sport. In summary, sports medicine clinics provide a rich source of Australian football injury data, especially from the community and junior levels of participation. The inclusion of sports medicine clinic data provides a broader epidemiological picture of Australian football injuries. This broader understanding of the pattern of Australian football injuries provides a better basis for the development of injury prevention measures in this sport.

Psychosocial epidemiology of colorectal cancer

The research explored the role played by personality and stress in the development and progress of colorectal cancer. Personality type was related to health outcomes following diagnosis, and to participation in bowel cancer screening. The personality types also differed in terms of their capacity to deal with stress.

The epidemiology of ecstasy use and harms in New South Wales, Australia

Aims:This paper examines the epidemiology of ecstasy use and harm in Australia using multiple data sources.

Design: The data included (1) Australian Customs Service 3,4-methylenedioxymethamphetamine (MDMA) detections; (2) the National Drug Strategy Household and Australian Secondary Student Alcohol and Drug Surveys; (3) data from Australia's ecstasy and Related Drugs Reporting System; (4) the number of recorded police incidents for ecstasy possession and distribution collated by the N.S.W. Bureau of Crime Statistics and Research; (5) the number of calls to the Alcohol and Drug Information Service and Family Drug Support relating to ecstasy; (6) the Alcohol and Other Drug Treatment Services National Minimum Dataset on number of treatment episodes for ecstasy, and (7) N.S.W. Division of Analytical Laboratories toxicology data on number of deaths where MDMA was detected.

Findings: Recent ecstasy use among adults in the general population has increased, whereas among secondary students it has remained low and stable. The patterns of ecstasy consumption among regular ecstasy users have changed over time. Polydrug use and use for extended periods of time (>48 h) remain common among this group. Frequent ecstasy use is associated with a range of risk behaviours and other problems, which tend to be attributed to a number of drugs along with ecstasy. Few ecstasy users present for treatment for problems related to their ecstasy consumption.

Conclusions: Messages and interventions to reduce the risks associated with polydrug use and patterns of extended periods of use are clearly warranted. These messages should be delivered outside of traditional health care settings, as few of these users are engaged with such services.

Effects of infection-induced migration delays on the epidemiology of avian influenza in wild mallard populations

Wild waterfowl populations form a natural reservoir of Avian Influenza (AI) virus, and fears exist that these birds may contribute to an AI pandemic by spreading the virus along their migratory flyways. Observational studies suggest that individuals infected with AI virus may delay departure from migratory staging sites. Here, we explore the epidemiological dynamics of avian influenza virus in a migrating mallard (Anas platyrhynchos) population with a specific view to understanding the role of infection-induced migration delays on the spread of virus strains of differing transmissibility. We develop a host-pathogen model that combines the transmission dynamics of influenza with the migration, reproduction and mortality of the host bird species. Our modeling predicts that delayed migration of individuals influences both the timing and size of outbreaks of AI virus. We find that (1) delayed migration leads to a lower total number of cases of infection each year than in the absence of migration delay, (2) when the transmission rate of a strain is high, the outbreak starts at the staging sites at which birds arrive in the early part of the fall migration, (3) when the transmission rate is low, infection predominantly occurs later in the season, which is further delayed when there is a migration delay. As such, the rise of more virulent AI strains in waterfowl could lead to a higher prevalence of infection later in the year, which could change the exposure risk for farmed poultry. A sensitivity analysis shows the importance of generation time and loss of immunity for the effect of migration delays. Thus, we demonstrate, in contrast to many current transmission risk models solely using empirical information on bird movements to assess the potential for transmission, that a consideration of infection-induced delays is critical to understanding the dynamics of AI infection along the entire flyway.

The epidemiology of cryptosporidiosis in New Zealand, 1997-2006

Aims New Zealand has a high incidence of cryptosporidiosis compared to other developed countries. This study aimed to describe the epidemiology of this disease in detail and to identify potential risk factors.

Methods We analysed anonymous cryptosporidiosis notification (1997–2006) and hospitalisation data (1996–2006). Cases were designated as “urban” or “rural” and assigned a deprivation level based on their home address. Association between disease rates and animal density was studied using a simple linear regression model, at the territorial authority level.

Results Over the 10-year period 1997–2006, the average annual rate of notified cryptosporidiosis was 22.0 cases per 100,000 population. The number of hospitalisations was equivalent to 3.6% of the notified cases. There was only 1 reported fatality. The annual incidence of infection appeared fairly stable, but showed marked seasonality with a peak rate in spring (September–November in New Zealand). The highest rates were among Europeans, children 0–9 years of age, and those living in low deprivation areas. Notification rates showed large geographic variations, with rates in rural areas 2.8 times higher than in urban areas, and with rural areas also experiencing the most pronounced spring peak. At the territorial authority (TA) level, rates were also correlated with farm animal density.

Conclusions Most transmission of Cryptosporidium in New Zealand appears to be zoonotic: from farm animals to humans. Prevention should focus on reducing transmission in rural setting, though more research is needed to identify which strategies are likely to be most effective in that environment.

The epidemiology of giardiasis in New Zealand, 1997-2006

Aims New Zealand has a higher incidence rate of giardiasis than other developed countries. This study aimed to describe the epidemiology of this disease in detail and to identify potential risk factors.

Methods We analysed anonymous giardiasis notification (1997–2006) and hospitalisation data (1990–2006). Cases were designated as urban or rural and assigned a deprivation level based on their home address. Association between disease rates and animal density was studied using a simple linear regression model, at the territorial authority (TA) level.

Results Over the 10-year period 1997–2006 the average annual rate of notified giardiasis was 44.1 cases per 100,000 population. The number of hospitalisations was equivalent to 1.7% of the notified cases. There were 2 reported fatalities. The annual incidence of notified cases declined over this period whereas hospitalisations remained fairly constant. Giardiasis showed little seasonality. The highest rates were among children 0–9 years old, those 30–39 years old, Europeans, and those living in low deprivation areas. Notification rates were slightly higher in rural areas. The correlation between giardiasis and farm animal density was not significant at the TA level.

Conclusions The public health importance of giardiasis to New Zealand mainly comes from its relatively high rates in this country. The distribution of cases is consistent with largely anthroponotic (human) reservoirs, with a relatively small contribution from zoonotic sources in rural environments and a modest contribution from overseas travel. Prevention efforts could include continuing efforts to improve hand washing, nappy handling, and other hygiene measures and travel health advice relating to enteric infections.

A tale of two parasites : the comparative epidemiology of cryptosporidiosis and giardiasis

New Zealand has a higher reported incidence of cryptosporidiosis and giardiasis than most other developed countries. This study aimed to describe and compare the epidemiology of these infections in New Zealand, to better understand their impact on public health and to gain insight into their probable modes of transmission. We analysed cryptosporidiosis and giardiasis notification data for a 10-year period (1997–2006). Highest rates for both diseases were in Europeans, children aged 0–5 years, and those living in low-deprivation areas. Cryptosporidiosis distribution was consistent with mainly farm animal (zoonotic) reservoirs. There was a dose–response relationship with increasing grades of rurality, marked spring seasonality, and positive correlation with farm animal density. Giardiasis distribution was consistent with predominantly human (anthroponotic) reservoirs, with an important contribution from overseas travel. Further research should focus on methods to reduce transmission of Cryptosporidium in rural areas and on reducing anthroponotic transmission of Giardia.