Transovarian and Transstadial Transmission

Transovarial or transovarian transmission (transmission from parent to offspring via the ovaries) occurs in certain

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

s as they transmit

pathogens In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ...

from parent to offspring. This process, used by a wide variety of parasites, is also known as vertical transmission. For example, ''

Rickettsia rickettsii ''Rickettsia rickettsii'' is a Gram-negative, intracellular, cocco-bacillus bacterium that was first discovered in 1902. Having a reduced genome, the bacterium harvests nutrients from its host cell to carry out respiration, making it an organo ...

'', carried within

tick Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, and species, but can become larger when engorged. Ticks a ...

s, is passed on from parent to offspring tick by transovarial transmission. This is in contrast to parasites such as ''

Rickettsia prowazekii ''Rickettsia prowazekii'' is a species of gram-negative, obligate intracellular parasitic, aerobic bacilliform bacteria of class Alphaproteobacteria that is the etiologic agent of epidemic typhus, transmitted in the feces of lice. In North Am ...

,'' which are not passed on by transovarian transmission due to killing the vector that carries it (in this case, the human louse). Other examples of parasites that use this mechanism of transmission include the

aedes ''Aedes'' (also known as the tiger mosquito) is a genus of mosquitoes originally found in tropical and subtropical zones, but now found on all continents except Antarctica. Some species have been spread by human activity: ''Aedes albopictus'', ...

mosquito vector of the yellow fever virus and in phlebotomine sandflies that transmit pappataci fever. Richard Dawkins in ''The Extended Phenotype'' notes that "bacterial endosymbionts of insects which are transmitted transovarially" share an interest in the "success of their host's gametes ... as well as the survival of their host's body." In this case, "the interest of the host genes and parasite genes might not be quite identical, but they would..... be very much closer than the case of fluke and snail." where host and parasite have different means of propagation into the next generation, and therefore more divergent interests.

References

* Murray, Patrick R.; Rosenthal, Ken S.; Pfaller, Michael A. Medical Microbiology, Fifth Edition. United States: Elsevier Mosby, 2005 Parasitology Epidemiology {{zoology-stub

See also

References