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Transmission can also be indirect, via another organism, either a vector (e.g. a mosquito or fly) or an intermediate host (e.g. tapeworm in pigs can be transmitted to humans who ingest improperly cooked pork). Indirect transmission could involve zoonoses or, more typically, larger pathogens like macroparasites with more complex life cycles.
For example, avian influenza survives on both porous and non-porous materials for 144 hours. [13] The microbes may also be transmitted by poor use of cutlery or improper sanitation of dishes or bedlinen. Particularly problematic are toilet practices, which lead to the fecal–oral route. STDs are by definition spread through this vector ...
An example is the viral transfer of DNA from one bacterium to another and hence an example of horizontal gene transfer. [2] [3] [page needed] Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA (which occurs in conjugation), and it is DNase resistant (transformation is susceptible to ...
For example, one study [12] used serial passage in baboons to create a strain of HIV-2 that is particularly virulent to baboons. Typical strains of HIV-2 only infect baboons slowly. [ 12 ] This specificity makes it challenging for scientists to use HIV-2 in animal models of HIV-1, because the animals in the model will only show symptoms slowly.
Transovarial and transstadial transmission of the Ixodes tick. Transstadial transmission is the persistence of a symbiont or pathogen in an organism from one life stage ("stadium") to the next, such as larva to nymph to adult. [1] [2] [3] This type of transmission is typically observed in insects.
Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. Because the evolutionary fate of the agent is not tied to reproductive success of the host, horizontal transmission tends to evolve virulence .
Proventricular dilatation disease (PDD) is an incurable probably viral disease of psittacine birds. It was first recognized and described in 1978 by Dr. Hannis L. Stoddard. Since the first reported cases were involving species of macaw, the condition was termed macaw wasting syndrom
Vertical transmission of symbionts is the transfer of a microbial symbiont from the parent directly to the offspring. [1] Many metazoan species carry symbiotic bacteria which play a mutualistic , commensal , or parasitic role. [ 1 ]