Pandemic epidemic of infectious disease spread

And what is the difference between an epidemic and a pandemic?

Pandemic epidemic of infectious disease spread

Mixed Other A common-source outbreak is one in which a group of persons are all exposed to an infectious agent or a toxin from the same source. If the group is exposed over a relatively brief period, so that everyone who becomes ill does so within one incubation period, then the common-source outbreak is further classified as a point-source outbreak.

Pandemic epidemic of infectious disease spread

The epidemic of leukemia cases in Hiroshima following the atomic bomb blast and the epidemic of hepatitis A among patrons of the Pennsylvania restaurant who ate green onions each had a point source of exposure.

Centers for Disease Control and Prevention. In some common-source outbreaks, case-patients may have been exposed over a period of days, weeks, or longer.

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In a continuous common-source outbreak, the range of exposures and range of incubation periods tend to flatten and widen the peaks of the epidemic curve Figure 1. The epidemic curve of an intermittent common-source outbreak often has a pattern reflecting the intermittent nature of the exposure.

A propagated outbreak results from transmission from one person to another. Usually, transmission is by direct person-to-person contact, as with syphilis.

Transmission may also be vehicleborne e. In propagated outbreaks, cases occur over more than one incubation period. The epidemic usually wanes after a few generations, either because the number of susceptible persons falls below some critical level required to sustain transmission, or because intervention measures become effective.

Some epidemics have features of both common-source epidemics and propagated epidemics. The pattern of a common-source outbreak followed by secondary person-to-person spread is not uncommon.

These are called mixed epidemics. For example, a common-source epidemic of shigellosis occurred among a group of 3, women attending a national music festival Figure 1. Many developed symptoms after returning home. Over the next few weeks, several state health departments detected subsequent generations of Shigella cases propagated by person-to-person transmission from festival attendees.

An outbreak of shigellosis at an outdoor music festival. Am J Epidemiol ; Finally, some epidemics are neither common-source in its usual sense nor propagated from person to person.

Outbreaks of zoonotic or vectorborne disease may result from sufficient prevalence of infection in host species, sufficient presence of vectors, and sufficient human-vector interaction.

Summary of notifiable diseases — United States, Hepatitis A outbreak associated with green onions at a restaurant—Monaca, Pennsylvania, MMWR ; 52 On the estimation of the incubation period in malignant disease. J Chron Dis ;9: Methods in observational epidemiology. Oxford University Press; Am J Epidemiol Means RG, et al.

Geographic spread and temporal increase of the Lyme diseas. Prevalence of overweight and obesity among adults with diagnosed diabetes — United States. National Center for Health Statistics [Internet]. Centers for Disease Control and Prevention [updated Feb 8].WHO’s primary role is to direct and coordinate international health within the United Nations’ system.

WHO main areas of work include: health systems, promoting health through the life-course, noncommunicable diseases, communicable diseases, corporate services, preparedness, surveillance and .

Gates compared the risk of a pandemic disease outbreak to the challenges of preparing for a massive war. An influenza pandemic is an epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the world contrast to the regular seasonal epidemics of influenza, these pandemics occur irregularly – there have been about 9 influenza pandemics during the last years.

Pandemics can cause high levels of mortality, with the Spanish influenza. ‘It takes just a single crisis — an epidemic, a natural disaster or even the death of a key physician who falls victim to disease — to make whole health care systems and economies come crashing to the ground,’ says Dr.

Lori Stetz, Senior Medical Director, Aetna International. A pandemic (from Greek πᾶν pan "all" and δῆμος demos "people") is an epidemic of infectious disease that has spread across a large region; for instance multiple continents, or even worldwide..

A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic. Further, flu pandemics generally exclude recurrences of seasonal flu. Animal influenza viruses are distinct from human seasonal influenza viruses and do not easily transmit between humans.

However, zoonotic influenza viruses - animal influenza viruses that may occasionally infect humans through direct or indirect contact - can cause disease in .

Principles of Epidemiology | Lesson 1 - Section 11