However, it is their capacity as vectors of viral, bacterial, protozoal and helminth diseases that has attracted much study to parasitic arthropods. It is this aspect of arthropods that will be focused on in these lectures. It seems incredible that it was not until 1877 that blood-sucking insects were conclusively shown to be vectors of disease. Patrick Manson, working in China, discovered the developmental stages of the filarial nematode Wuchereria bancrofti in the mosquito, Culex fatigans . W. bancrofti is the causative agent of elephantiasis in humans.
Mosquitoes are the most widespread and important vectors of human and animal diseases.
For all mosquitoes, transmission to and from the insect takes place through the mouthparts, which are designed to puncture skin as would a hypodermic needle. Feeding occurs usually at dusk and at night. Eggs are laid in water, and for some species, even a water-filled footstep will suffice for egg and larval development. There are two subfamilies of mosquitoes, Anophelinae and Culicinae, which differ in egg morphology and disposition, larval position in relation to water surface and the resting position of the adult. Aedes can transmit the filarial nematodes Brugia spp .