[5] Sporadic non-infectious diseases arise not due to any identifiable inherited gene, but because of randomly induced genetic mutations under the influence of environmental factors or of some unknown etiology.
Although the tetanus-causing bacteria Clostridium tetani is present in the soil everywhere in the United States, tetanus infections are very rare and occur in scattered locations because most individuals have either received vaccinations or clean wounds appropriately.
[6] In another example, World Health Organization defines malaria to be sporadic when autochthonous cases (i.e. between two individuals in the same place) are too few and scattered to have any appreciable effect on the community.
[8] In another example, the South Asian country of Bangladesh experienced sporadic cases of dengue fever, a mosquito-borne disease, from its first outbreak in 1964 until 1999.
[9] However, in 2000, the arrival of a Thai/Myanmar strain of the highly pathogenic dengue type 3 virus into the overpopulated and poorly urbanized country (which increases human-mosquito contact), with highly favorable breeding grounds (such as open water reservoirs used by poor people and accumulation of rainwater) for the vector, and very little public awareness gave rise to a sudden epidemic of dengue, with 5,551 reported cases that year.