Outbreak is a term used in epidemiology to describe an occurrence of disease greater than would otherwise be expected in a particular time and place. It may be small and localized group or impact upon thousands of people across an entire continent. Two linked cases of a rare infectious disease may be sufficient to constitute an outbreak. Outbreaks may also refer to epidemics, which affect a region in a country or a group of countries, or pandemics, which describe global disease outbreaks.

Contents 1 Outbreak investigation 2 Types 3 Outbreak legislation 4 Notes 5 External links

[edit] Outbreak investigation

When investigating disease outbreaks, the epidemiology profession has developed a number of widely accepted steps. As described by the Centers for Disease Control and Prevention, these include the following^[1]:

• Verify the diagnosis related to the outbreak
• Identify the existence of the outbreak: is the group of ill persons normal for the time of year, geographic area, etc.?
• Create a case definition to define who/what is included as a case
• Complete descriptive epidemiology: describe outbreak with respect to time, place, and people
• Develop a hypothesis: what appears to be causing the outbreak?
• Study hypothesis: collect data and perform analysis
• Refine hypothesis and carry out further study
• Develop and implement control and prevention systems
• Release findings to greater community

[edit] Types

There are several outbreak patterns, which can be useful in identifying the transmission method or source, and predicting the future rate of infection. Each has a distinctive epidemic curve, or histogram of case infections and deaths.^[2]

• Common source - All victims acquire the infection from the same source (e.g. a contaminated water source).^[3]
  • Continuous source - Common source outbreak where the exposure occurs over multiple incubation periods.
  • Point source - Common source outbreak where the exposure occurs in less than one incubation period^[4]
• Propagated - Transmission occurs from person to person.^[5]

Outbreaks can also be:

• Behavioral risk related (e.g., sexually transmitted diseases, increased risk due to malnutrition)^[6]
• Zoonotic - The infectious agent is endemic to an animal population.

patterns of occurence are:

• epidemic- a communicable disease, such as influenza, measles, mumps, pneumonia, colds, small pox found permanently in a particular region or population.

• endemic- when this disease is found to infect "a lot of" people at the same time and may spread through one or several community.

• pandemic- occurs when the epidemic spreads across the world.

[edit] Outbreak legislation

Outbreak legislation is still in its infancy and not many countries have had a direct and complete set of the provisions ^{[7], [8]}. However, some countries do manage the outbreaks using relevant acts, such as public health law ^[9].

[edit] Notes

Look up outbreak in Wiktionary, the free dictionary.

1. ^ EXCITE | Epidemiology in the Classroom | Outbreak Steps
2. ^ http://ccnmtl.columbia.edu/projects/epiville/study5d.html
3. ^ http://www.cdc.gov/excite/library/glossary.htm#outbreakcommonsource
4. ^ http://www.cdc.gov/excite/library/glossary.htm#outbreakpointsource
5. ^ http://www.cdc.gov/excite/library/glossary.htm#outbreakpropagated
6. ^ http://www.cdc.gov/doc.do/id/0900f3ec802272e6
7. ^ Bioterrorism Training and Curriculum Development Program. "Outbreak Law". http://library.scahec.net/view/product/32. Retrieved 2 August 2008. 
8. ^ Star Publications. "‘Outbreak actions protected by law’". http://thestar.com.my/news/story.asp?file=/2008/7/16/courts/21834412&sec=courts. Retrieved 2 August 2008. 
9. ^ The State of Queensland Government. "Legislation and Powers of Entry". http://www.health.qld.gov.au/dengue/managing_outbreaks/legislation.asp. Retrieved 2 August 2008. 

[edit] External links

• Outbreak Alerts Resource for breaking news on outbreaks of communicable diseases.