There are four types of biological transmission , they are :
A- PROPOGATIVE TRANSMISSION - in this type of transmission only multiplication of the organism takes place in the host without any kind of development that is change in form . example for this type of transmission is THE PLAGUE BACILLUS IN THE RAT FLEA.
B -CYCLOPROPOGATIVE TRANSMISSION - in this type of transmission not only does the parasite multiply vigorously it also changes its form . example for such type of transmission is
malaria parasite undergoing its sexual life cycle in the female anopheles mosquito.
C-CYCLODEVELOPMENTAL TRANSMISSION - in this type of transmission the parasite only undergoes change in form or development in the host but does not multiply .example for this type of transmission is the FILARIAL PARASITE IN CULEX MOSQUITO .
D- MECHANICAL TRANSMISSION - in this type of transmission there is neither change in the form of the parasite in the host nor multiplication of the parasite in the host .