Transstadial_transmission
Transstadial transmission occurs when a pathogen remains with the vector from one life stage ("stadium") to the next.[1][2][3] For example, the bacteria Borrelia burgdorferi, the causative agent for Lyme disease, infects the tick vector as a larva, and the infection is maintained when it molts to a nymph and later develops as an adult.[1][2] This type of transmission is seen in other parasites like viruses or Rickettsia.[3] In addition to ticks, mites are another common vector.[3][4] Some sources consider transstadial transmission a type of horizontal transmission,[5][6] whereas other sources consider it vertical or partial vertical transmission.[7][8]
Transstadial blockage could be considered the opposite of transstadial transmission, where the parasite cannot be carried over from one life stage to the next.[4] For example, viruses that undergo transstadial blockage will have decreased infectivity in molting insects.[4]