propagated outbreak

Examples of propagated outbreak in the following topics:

• 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 was continuous or variable, it can be termed a continuous outbreak or intermittent outbreak, respectively.
  • (2) In a propagated outbreak, the disease spreads person-to-person.
  • Many epidemics will have characteristics of both common source and propagated outbreaks.
  • Give examples of disease reservoirs and distinguish between common source and propagated outbreaks

• Occurrence of a Disease

  • An occurrence of disease greater than would be expected at a particular time and place is called an outbreak.
  • Two linked cases of a rare infectious disease may be sufficient to constitute an outbreak.
  • Outbreaks may also refer to endemics that affect a particular place or group, epidemics that affect a region in a country or a group of countries, and pandemics that describe global disease outbreaks .
  • Develop a hypothesis (if there appears to be a cause for the outbreak).
  • Point source – Common source outbreak where the exposure occurs in less than one incubation period.

• Emerging Viral Hemorrhagic Fevers

  • The virus thus has the advantage of possibly having several natural reservoirs to propagate in.
  • 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.

• Chikungunya Fever

  • Both Ae. aegypti and Ae. albopictus have been implicated in large outbreaks of CHIKV.
  • 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.
  • In 2007 transmission was reported for the first time in Europe, in a localized outbreak in north-eastern Italy.

• Prions

  • Prions propagate by transmitting a misfolded protein state.
  • Propagation of the prion depends on the presence of normally-folded protein in which the prion can induce misfolding; animals which do not express the normal form of the prion protein cannot develop nor transmit the disease.
  • However, a model of prion replication must explain both how prions propagate, and why their spontaneous appearance is so rare.
  • Recent studies propagating TSE infectivity in cell-free reactions and in purified component chemical reactions strongly suggest against TSE's viral nature.

• Analytical Epidemiology

  • Analytical epidemiology attempts to determine the cause of an outbreak.
  • In this way, other possible factors, e.g., genetic or environmental, might be identified as factors related to the outbreak .

• Emerging and Reemerging Infectious Diseases

  • Between November 2002 and July 2003, an outbreak of SARS in Hong Kong nearly became a pandemic, with 8,422 cases and 916 deaths worldwide (10.9% fatality), according to the World Health Organization (WHO).
  • 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.
  • 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.

• 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.
  • 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.

• 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.

• Vaccination

  • Vaccination is a proven way to prevent and even eradicate widespread outbreaks of life-threatening infectious diseases.