Climate, human behaviour or environment: individual-based modelling of Campylobacter seasonality and strategies to reduce disease burden
Authored by Stephen P Rushton, Roy A Sanderson, Peter J Diggle, Mark D F Shirley, Alasdair P Blain, Iain Lake, James A Maas, William D K Reid, Jo Hardstaff, Nicola Williams, Natalia R Jones, Daniel Rigby, Norval J C Strachan, Ken J Forbes, Paul R Hunter, Thomas J Humphrey, Sarah J O'Brien
Date Published: 2019
DOI: 10.1186/s12967-019-1781-y
Sponsors:
United Kingdom Economic and Social Research Council (ESRC)
United Kingdom Natural Environment Research Council (NERC)
British Biological Sciences Research Council
British Medical Research Council
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Flow charts
Model Code URLs:
https://gitlab.com/rasanderson/campylobacter-microsimulation
Abstract
Background: With over 800 million cases globally, campylobacteriosis is
a major cause of food borne disease. In temperate climates incidence is
highly seasonal but the underlying mechanisms are poorly understood,
making human disease control difficult. We hypothesised that observed
disease patterns reflect complex interactions between weather, patterns
of human risk behaviour, immune status and level of food contamination.
Only by understanding these can we find effective interventions.
Methods: We analysed trends in human Campylobacter cases in NE England
from 2004 to 2009, investigating the associations between different risk
factors and disease using time-series models. We then developed an
individual-based (IB) model of risk behaviour, human immunological
responses to infection and environmental contamination driven by weather
and land use. We parameterised the IB model for NE England and compared
outputs to observed numbers of reported cases each month in the
population in 2004-2009. Finally, we used it to investigate different
community level disease reduction strategies.
Results: Risk behaviours like countryside visits (t = 3.665, P < 0.001
and t = -2.187, P = 0.029 for temperature and rainfall respectively),
and consumption of barbecued food were strongly associated with weather,
(t = 3.219, P = 0.002 and t = 2.015, P = 0.045 for weekly average
temperature and average maximum temperature respectively) and also rain
(t = 2.254, P = 0.02527). This suggests that the effect of weather was
indirect, acting through changes in risk behaviour. The seasonal pattern
of cases predicted by the IB model was significantly related to observed
patterns (r = 0.72, P < 0.001) indicating that simulating risk behaviour
could produce the observed seasonal patterns of cases. A vaccination
strategy providing short-term immunity was more effective than
educational interventions to modify human risk behaviour. Extending
immunity to 1 year from 20 days reduced disease burden by an order of
magnitude (from 2412-2414 to 203-309 cases per 50,000 person-years).
Conclusions: This is the first interdisciplinary study to integrate
environment, risk behaviour, socio-demographics and immunology to model
Campylobacter infection, including pathways to mitigation. We conclude
that vaccination is likely to be the best route for intervening against
campylobacteriosis despite the technical problems associated with
understanding both the underlying human immunology and genetic variation
in the pathogen, and the likely cost of vaccine development.
Tags
Epidemiology
cattle
contamination
Weather
Individual-based modelling
Vaccination
Research-and-development
Immunity
Food
Risk-factors
Campylobacter
Risk behaviours
Infectious intestinal disease
Source attribution
Jejuni
Northeastern