Alternaria tenuissima

Alternaria tenuissima is a cosmopolitan species, common on an array of various plant hosts in many countries spanning a range of environmental conditions. It often colonizes blueberries, tomatoes, grapevine, and strawberries. It has also been found on several cereal grain species. Optimal growth occurs between 25–30 °C (77–86 °F). Although A. tenuissima is normally an opportunistic pathogen of plants, rare cases of skin infections in immunocompromised people have been reported.

Cutaneous and subcutaneous alternariosis is a skin or tissue infection caused by members of the genus Alternaria, most commonly A. alternata and A. tenuissima. Because of the inability of A. tenuissima to invade healthy host tissue, alternariosis tends to be restricted to people with abrogated cellular immunity and occasionally the elderly. Complication following organ transplantion, Cushing's syndrome and immunosuppressive therapies are some of the typical settings in which alternariosis has been reported. Alternariosis appears on the skin as red pustules that may produce ulcers over time. Alternaria tenuissima is a prolific producer of the allergen Alt a 1. Exposure to this protein can induce an allergic reaction in sensitized individuals by reacting with circulating IgE antibody. Exposure to Alt a 1 has been associated with asthmatic exacerbation. Alternaria tenuissima also produces the mycotoxin tenuazonic acid which has received attention as a candidate antitumor medication.