ABSTRACT
OBJECTIVES: Measles was endemic in England during the early 1800s; however, it did not arrive in Australia until 1850 whereas other infectious diseases were known to have arrived much earlier-many with the First Fleet in 1788-leading to the question of why there was a difference. DESIGN: Ships surgeons' logbooks from historical archives, 1829-1882, were retrospectively reviewed for measles outbreak data. Infectious disease modelling techniques were applied to determine whether ships would reach Australia with infectious measles cases. SETTING: Historical ship surgeon logbooks of measles outbreaks occurring on journeys from Britain to Australia were examined to provide new insights into measles epidemiology. PRIMARY AND SECONDARY OUTCOME MEASURES: Serial intervals and basic reproduction numbers (R(0)), immunity, outbreak generations, age-distribution, within-family transmission and outbreak lengths for measles within these closed cohorts. RESULTS: Five measles outbreaks were identified (163 cases). The mean serial interval (101 cases) was 12.3 days (95% CI 12.1 to 12.5). Measles R(0) (95 cases) ranged from 7.7-10.9. Immunity to measles was lowest among children ≤10 years old (range 37-42%), whereas 94-97% of adults appeared immune. Outbreaks ranged from 4-6 generations and, before 1850, were 41 and 38 days in duration. Two outbreaks after 1850 lasted longer than 70 days and one lasted 32 days. CONCLUSIONS: Measles syndrome reporting in a ship surgeon's logs provided remarkable detail on prevaccination measles epidemiology in the closed environment of ship voyages. This study found lower measles R(0) and a shorter mean clinical serial interval than is generally reported. Archival ship surgeon log books indicate it was unlikely that measles was introduced into Australia before 1850, owing to high levels of pre-existing immunity in ship passengers, low numbers of travelling children and the journey's length from England to Australia.
ABSTRACT
BACKGROUND: The relationship between weather and food-borne diseases has been of great concern recently. However, the impact of weather variations on food-borne disease may vary in different areas with various geographic, weather and demographic characteristics. This study was designed to quantify the relationship between weather variables and Campylobacter infections in two Australian cities with different local climatic conditions. METHODS: An ecological-epidemiological study was conducted, using weekly disease surveillance data and meteorological data, over the period 1990-2005, to quantify the relationship between maximum and minimum temperatures, rainfall, relative humidity and notifications of Campylobacter infections in Adelaide, with a temperate Mediterranean climate, and Brisbane, with a sub-tropical climate. Spearman correlation and time-series adjusted Poisson regression analyses were performed taking into account seasonality, lag effects and long-term trends. RESULTS: The results indicate that weekly maximum and minimum temperatures were inversely associated with the weekly number of cases in Adelaide, but positively correlated with the number of cases in Brisbane, with relevant lagged effects. The effects of rainfall and relative humidity on Campylobacter infection rates varied in the two cities. CONCLUSION: Weather might have different effect on Campylobacter infections in different cities. Further studies are needed for a better understanding of these relationships for they may indicate epidemiologic factors important for control of these infections.
