Summary: Insects relevant for human diseases in the tropics
Of the more of one million described species of insects it is only a small but significant number of some 17,000 which have adapted to a bloodsucking mode of life. Some of these became important biting pests, causes of diseases and vectors of disease pathogens, in particular of tropical diseases.
Haematophagy has evolved independently in four orders of insects, the lice (Anoplura), the bugs (Heteroptera), the true flies (Diptera) and the fleas (Siphonaptera). An overview is given on their importance as vectors of diseases caused by arboviruses (Dengue, Yellow Fever etc.), bacteria (rickettsioses, plague, borrelioses, bartonelloses), protozoa (malaria, leishmanioses, sleeping sickness, Chagas disease) or filarioses.
Crucial is the biological transmission, which involves a multiplication of the pathogen without change of form in various organs of the vector (Arboviruses, Rickettsiae, Bacteria), a multiplication with change of form (Protozoa) or a development without multiplication but change of form (Filaria).
Since developmental duration of the pathogen in a vector from its uptake with a blood meal until it reaches its infective stage (the extrinsic incubation) heavily depends on the temperature, climatic warming has the potential of enhancing the spread of vector borne diseases.