Human diseases associated with fish pathogens

Abstract

Until recently, most cases of humans been affected by fish pathogens, bacterial and parasitic, were limited in certain countries, either due to the inappropriate sanitary measures used in those areas, or due to the local habit of eating raw or undercooked fish. However, as new reliable methods to identify fish pathogens in samples collected from sick humans have been developed, the confirmed cases worldwide have increased. The most common fish bacterial pathogens that can affect humans belong to the genera: Mycobacterium spp. (mainly M. marinum, M. chelonei, M. fortuitum), Nocardia spp., Streptococcus spp (S. iniae), Vibrio spp. (mainly V. vulnificus, V. alginolyticus and V. parahaemolyticus) and Aeromonas spp. (mainly A. hydrophila and rarely A. sorbia and A. caviae). Less often, infections of humans with Edwardsiella tarda and Photobacterium damselae sbsp. damselae have been reported. Fish usually act as intermediate hosts to many important parasites of human, as for example the tapeworm Diphyllobothrium latum. To fish, these parasites cause no or little damage, as they are usually found encysted in many fish tissues. Of particular interest are someanisakids (e.g. Anisakis simplex and Pseudoterranova decipiens) which can produce some thermostable allergens. Most of the above pathogens can infect humans through skin wounds or after ingesting infected fish. Compromised immune system of the infected humans may result in extensive spread of the pathogens within the body, often causing death.There are no fish viruses or fungi that can affect humans. Fish can also act as carriers for human pathogens, such as Salmonella spp., Escherichia coli and Listeria spp. Recently, few human pathogens have also been isolated from the internal organs of fish, as for example Brucella melitensis. The effects of these human pathogens to fish are still not known.

Keywords

• human diseases
• fish
• pathogens