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Monitoring Disease Activity

Biology (Year 12) - Pathogen Management Strategies

Ben Whitten

What is monitoring disease activity? In order to control and define disease outbreaks, public health authorities need to know when and where particular infections are occurring. Disease is actively and globally monitored by the World Health Organisation (WHO), and in Australia, a list of 70 notifiable diseases must be reported and notified of diagnoses including influenza, rubella and chickenpox. Outbreaks can then be investigated. How is disease activity monitored? Global level monitoring

  • WHO monitors disease activity

  • Coordinates global responses to outbreaks


  • Disease cases monitored by health authorities in each state

  • Notifiable diseases: public health authorities are informed by doctors over 70 different infectious diseases

  • Outbreaks then investigated, e.g. ross river virus outbreak in QLD

  • Limitations: under-reported cases/misinformation/time delays

  • Incubation time limits speedy responses to outbreaks/epidemics

Internet/social media surveillance

  • Data from social media can provide information about disease frequency

  • Google search trackers used for frequency of searches for conditions

  • Advantage: real time information

  • Disadvantage: data determined by algorithms, does not always correspond with outbreaks, celebrity bias in data

  • Outcome: wont replace reporting but good as supplementary source

How is an outbreak managed?

  1. Confirm cases meet the criteria for an outbreak

  2. Investigators form a case definition (illness, place and time)

  3. Finding cases, gathering information and developing hypothesis

  4. Contact tracing; people who have been infected are tracked down

  5. Finding the index case (patient zero), the case that started the outbreak

  6. Interviews conducted, environment sampling, information collected

  7. Hypothesis further developed and tested

  8. Implement control measures to control the spread and communicate findings

How can disease spread be predicted? Mathematical models can be used to predict the spread of a disease, and are important in controlling an outbreak. For a model to have good predictability, it needs to both;

  • Reflect the complexity of a pathogen

  • Consider the host, environment and pathogen relationships

What is epidemiology? Epidemiology is the branch of medicine which is concerned with the distribution, incidence and control of disease. Though there are improvements in prevention and treatments of disease, infectious diseases are still a major cause of death globally. The burden of diseases varies between countries. A lack of access to healthcare, good sanitation, clean drinking water and good nutrition can affect the burden of a disease. Epidemiological studies are used to analyse for possible causes of a disease.

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