Alternaria species (approximately 299) are abundant in the environment. They are normal agents of decay and decomposition of organic matter.
Some Alterneria are plant pathogens infecting both fruit and vegetable commodities leading to agriculture spoilage. The spores are readily airborne and are present in soil and water and in the air, outdoors as well as indoors, and are found on building materials.
Alternaria produce several mycotoxins: Tenuazonic acid (TA), Alter toxin I (ATX-I), Altenuene (ALT), Alternariol (AOH), Alternariol monomethyl ether (AME), and Tentoxin (TEN). (Centeno and Calvo, 2002; Logiieco et al, 2003).
Carcinogenicity of Alternaria Mycotoxins
Esophageal cancer has been associated with the consumption of contaminated grain containing AME and AOH produced by A. aitemata (Liu, 1992). Mutagenicity of A. alternata mycotoxins has been demonstrated in tissue mammalian cells and human esophageal epithelium in vitro (Zhang, 1991; Lehmann et al, 2006; Brugger et al, 2006).
In addition, Tenuazonic acid following oral feeding caused dysplasia of the esophageal mucosa of mice (Yekeler et al, 2000). These reports suggest that additional research on potential carcinogenicity of Alternaria mycotoxins is warranted.
Human Health and Alternaria
Alternaria spp are opportunistic pathogens particularly in immunecompromised individuals causing infections as follows: onychomycosis, sinusitis, keratitis, osteomyelitis and visceral infections (Morrison et el, 1994; Vativarian et al, 1993).
Phaeohyphomycosis has also been reported (Dubois et al, 2005). The most important risk factors are organ and bone marrow transplants and Cushing's (Pastor and Guarro, 2008).
Skin infections and sinus colonization can occur in immunocompetent individuals (Vennewald et al, 1999; Manning et al, 1991; Di Silverio and Sacchi, 1986; Matson et al, 2010).
Alternariosis of the skin has been reported in farmers and otitis media in agriculture workers (Spiewak, 1998; Wadhwani and Srivastava, 1984).
Mold sensitivity in children with Alternaria moderate-severe asthma have been reported to have certain HLA (Human Leukocyte Antigen) alleles and genetic polymorphism in IL-4 RA single nucleotide (Knutsen et al 2010 a, b). These studies show that children with Alternaria sensitive asthma have a skewed TH2 response associated with an increased frequency of the IL-4RA ile75val polymorphism.
The TH2 sensitivity was associated with a HLA-DR restriction and increased frequency of HLA-DRB1*13 and HLA-DQB1*03 alleles. A decreased frequency of HLA-DQB1*103 was present in Alternaria sensitive patients, suggesting that this gene may be protective against the development of Alternaria-sensitive severe asthma.
In conclusion, Alternaria spp are present in both indoor and outdoor environments and are known to be present in WDB.
Alternariosis occurs in both immunocompromised and immunocompetent individuals. Alternaria can colonize the sinuses leading to sinusitis.
Finally, certain HLA genes render children, and probably adults, to be more sensitive to Alternaria causing moderate to severe asthma.