ABSTRACT
The biology of Dirofilaria immitis must be studied on two levels to understand the requirements for the parasite's survival. The first approach is to study the biology of individual organisms, the second is to observe the dynamics of the total population. The somatic musculature of D. immitis has morphological features of an obliquely striated muscle. The nuclear materials of D. immitis sperm, as well as other sperm contents, then dissolve into the ooplasm. The rates at which larvae survive, develop, and migrate within the mosquito are dependent on several factors. Genetic differences are seen in the capacity of mosquitoes to support D. immitis. D. immitis third-stage larvae measuring approximately 1.2 mm enter the dog. Investigations have been conducted to determine what mechanisms might control the level of peripheral microfilaremia found in dogs infected with D. immitis. Microfilaremic blood was transfused out of a dog infected with D. immitis and an equal volume of uninfected blood was used to replace it.
