Invertebrates carrying disease or causing annoyance

Some blood-sucking and stinging arthropods may cause pain by their attacks on the skin (see p. 33). Others may increase sensitivity, as mites do, for example, in the case of asthma (see p. 35). In rare cases the presence of certain in- vertebrates in foodstuffs may constitute a danger to health, as for instance when there are fly larvae in meat or large numbers of mites in cereal products. In addition, the mere presence of completely harmless animals has a depressing effect on certain people. There are several transitional stages from general malaise to a state of anxiety neurosis, sometimes with hallucinations, in which the patient believes that he or she is being persecuted by these small animals.