common source outbreak

Examples of common source outbreak in the following topics:

• Occurrence of a Disease

  • Develop a hypothesis (if there appears to be a cause for the outbreak).
  • There are several outbreak patterns that can be useful in identifying the transmission method or source and predicting the future rate of infection.
  • Common source – All victims acquire the infection from the same source (e.g. a contaminated water supply).
  • 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.

• Disease Reservoirs and Epidemics

  • There are two types of epidemic outbreaks: (1) In a common source outbreak, the affected individuals had an exposure to a common agent.
  • If the exposure is singular and all of the affected individuals develop the disease over a single exposure and incubation course, it can be termed a point-source outbreak.
  • Many epidemics will have characteristics of both common source and propagated outbreaks.
  • For example, secondary person-to-person spread may occur after a common source exposure or environmental vectors may spread a zoonotic disease agent.
  • Give examples of disease reservoirs and distinguish between common source and propagated outbreaks

• Legionellosis

  • In the 1970s, the CDC investigated a large outbreak of legionellosis at Baptist Hospital that was spread through its air conditioner.
  • Common sources of Legionella include swimming pools, cooling towers, hot-water systems such as spas, fountains, freshwater ponds and creeks.
  • As seen, the major source for Legionella bacteria is infected water.

• Chikungunya Fever

  • Both Ae. aegypti and Ae. albopictus have been implicated in large outbreaks of CHIKV.
  • Common laboratory tests for chikungunya include RT-PCR, virus isolation, and serological tests.
  • Human infections in Africa have been at relatively low levels for a number of years, but in 1999-2000 there was a large outbreak in the Democratic Republic of the Congo, and in 2007 there was an outbreak in Gabon.
  • Starting in February 2005, a major outbreak occurred in islands of the Indian Ocean.
  • A large outbreak of chikungunya in India occurred in 2006 and 2007.

• Finding Patient Zero and Tracking Diseases

  • The index case may indicate the source of the disease, the possible spread, and which reservoir holds the disease in-between outbreaks.
  • The index case is the first patient that indicates the existence of an outbreak.
  • He was vilified for several years as a "mass spreader" of HIV, and seen as the original source of the HIV epidemic among homosexual men.
  • In the eboloa outbreak of 2014, the Patient Zero was identified as a two year-old boy in Guinea who died on Dec. 2, 2013 of Ebolavirus during the fruitbat migration.

• Emerging and Reemerging Infectious Diseases

  • The last infected human case of the outbreak occurred in June 2003, and there was a laboratory-induced infection case in 2004.
  • During the outbreak, the fatality of SARS was less than 1% for people aged 24 or younger, 6% for those 25 to 44, 15% for those 45 to 64, and more than 50% for those over 65.
  • The most common symptoms are chills, fever, sore throat, muscle pains, headache (often severe), coughing, weakness/fatigue and general discomfort.
  • Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease caused by a different type of virus.
  • However, there was an outbreak in Algeria in 1994, with cases of WNV-caused encephalitis, and the first large outbreak in Romania in 1996, with a high number of cases with neuroinvasive disease.

• DNA Analysis Using Genetic Probes and PCR

  • Genotyping of pathogenic isolates provides valuable support during investigations of suspected outbreaks and when tracing infectious diseases.
  • It is well established that genotyping of pathogenic isolates provides valuable support for the investigation of suspected outbreaks, the detection of unsuspected transmission, the tracing of infectious agents within a community, and the identification of possible sources of infection for newly diagnosed cases.

• Current Epidemics

  • Epidemiologists often consider the term outbreak to be synonymous to epidemic, but the general public typically perceives outbreaks to be more local and less serious than epidemics.
  • A few cases of a very rare disease may be classified as an epidemic, while many cases of a common disease (such as the common cold) would not.
  • The most common symptoms are chills, fever, sore throat, muscle pains, headache (often severe), coughing, weakness/fatigue and general discomfort.
  • The World Health Organization officially declared the outbreak to be a pandemic level 6 on 11 June 2009.
  • However, the WHO's declaration of a pandemic level 6 was an indication of spread, not severity; the strain actually having a lower mortality rate than common flu outbreaks.

• Viral Genomes in Nature

  • The host range of some bacteriophages is limited to a single strain of bacteria and they can be used to trace the source of outbreaks of infections by a method called phage typing.
  • It is thought that viruses played a central role in the early evolution, before the diversification of bacteria, archaea, and eukaryotes and at the time of the last universal common ancestor of life on earth.

• Emerging Viral Hemorrhagic Fevers

  • A recent study using deep sequencing, discovered a novel rhabdovirus (Bas-Congo virus, or BASV) associated with a 2009 outbreak of three human cases of acute hemorrhagic fever in Mangala village, Democratic Republic of Congo (DRC), Africa.
  • Although the source of the virus remains unclear, the study findings suggest that BASV may be spread by human-to-human contact and is an emerging pathogen associated with acute hemorrhagic fever in Africa .