Most diseases acquired from insects are those in which the insect acts as a vector, transmitting the disease from an animal or human reservoir host to another human. Many examples exist such as African Sleeping Sickness caused by Trypanosoma brucei in which antelopes, cattle, and camels are reservoir hosts and the disease is transmitted via a tse tse fly. Another example is Trypanosoma cruzi which causes Chagas disease and is transmitted by a reduviid bug. Reservoir hosts for Chagas disease include opossums, armadillos, and raccoons.
However, a very interesting category of zoonoses caused by insects is transmission by edible insects. Edible insects are becoming more popular due to their high nutritional value and the fact that they can be prepared in many different ways. Some examples of edible insects include caterpillars, ants, beetles, wasps, grasshoppers, termites, and many others. They can cause disease in several ways: allergic reactions, diseases due to metabolic steroids that some insects contain, and enzyme inhibition from cyanogenic substances. Long horn beetles are known to contain toluene which can act as a nervous system depressant.
Additionally, a number of bacterial pathogens and parasitic infections have been transmitted by edible insects such as Campylobacter and the parasite Dicrocoelium dendriticum. Dicrocoelium in particular is interesting in that it is a fluke transmitted by ants and which mainly infects cows but occasionally humans. The image shows the very interesting life cycle of this parasite.
