Malaria -

Ans. is 'b' i.e., Cyclopropagative o In vector bom diseases, an arthropod or any living carrier (e.g., snail) acts as a vector and transports an infectious agent to a susceptible individual,o Transmission by a vector may be of following types : -Mechanical transmissionThe infectious agent is mechanically transported by vector, e.g., through souling of feet of flying arthropod.There is no development or multiplication of infectious agent within the vector.Biological transmissionThe infectious agent undergoes replication (change in number) or development (change in form) or both in vector.So, inectious agent requires an incubation period (extrinsic incubation period) before vector can transmit it to host.This type of transmission is of three types : -Propagativeo Agent undergoes multiplication (change in number) in the vector,o There is no development - No change in form,o Example - Plague bacilli in rate fleas.Cyclo-developmentalo Agent undergoes only development - Change in form,o No multiplication - No change in number,o Example - MicorfUaria in mosquito.Cyclo-propagativeo Agent undergoes both development and multiplication - Change in form and number,o Example - Malaria parasite (plasmodium sp.) in mosquito.