Parasite Transmission Flashcards
What is the advantage of a host environment?
constant conditions
What is the problem of a host environment?
host will die: must exit, id, & infect next host
What is transmission?
movement from host to host to ensure survival of subsequent generations
What is fecal-oral transmission?
parasite is released in host feces and contaminates food & water. a passive process that relies on chance encounters - success depends on high contamination of environment
What kind of strategy is fecal-oral transmission?
sit & wait - long time for host encounter
What is a challenge of the sit wait strategy? How does the parasite prepare for this?
must resist external environment condition during transmission stage: 1. egg or cyst w/ very thick walls 2. low metabolic rate - stored nutrients
What is trophic transmission?
parasite takes advantage of predatory-prey relationships and may manipulate behavior of IH: prey = IH & predator = DH
What is PITT?
parasite-increased tropic transmission: change in host’s behavior or physical characteristic increases chances of host being ingested (ex: Myrmeconema neotropicum - nematode that induces fruit mimicry)
What occurs in sexual transmission?
- no exposure to external environment 2. no specialized transmission stage (ex: Trichomonas vaginalis (Protozoan) Males – asymptomatic. Females – trichomonad vaginitis)
What occurs in vertical transmission?
infection of developing egg or embryo either in mother’s body or at the time of birth/egg laying
What is a sp example of vertical transmission?
toxoplasmia gondii (protozoan) - Cross over placenta and infect the fetus: can produce hydrocephaly
What is active transmission?
free living infective stage actively searches for and invades a host
What does active transmission require?
- reliably high density of potential hosts 2. ability to identify host 3. energy
What is a vector?
actively transmits parasite from host to host
What is a mechanical vector?
parasite does not undergo development
