Infections Acquired through the Gastro-intestinal Tract

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Of the important pathogens that gain entry through the gastro-intestinal tract many are cosmopolitan in their distribution. Some cause diarrhoeal diseases (eg cholera, shigellosis, enteric fever) while others pass from the intestinal tract to cause disease in other organs (eg poliomyelitis, infective hepatitis, trichinosis). The pathogens include viruses, bacteria, protozoa, helminths and endoparasitic arthropods. The first three of these are directly infectious for man when they are passed in the faeces but, in the case of helminths, the eggs may become infectious only after maturation in the soil (eg Ascaris), or after passing through an intermediate host (eg Taenia saginata).

The most important pattern of transmission is the passage of infective material from human faeces into the mouth of a new host, which is known as faeco-oral transmission. This occurs mostly through inapparent faecal contamination of food, water, and hands - the three main points of contact with the mouth. Some of the pathogens that infect through the mouth are not excreted in the faeces, eg guinea-worm infection is acquired by drinking contaminated water, but the larvae escape through the skin. On the other hand, while the ova of hookworm are passed in the faeces the route of human infection is by direct penetration of the skin by the larvae after a period of incubation of the egg in the soil.

A number of the infections that are acquired through the gastro­intestinal tract characteristically occur in epidemic form, eg cholera and typhoid. Other may be more localised affecting persons from the same household or institution, eg amoebiasis, enterobiasis. The most topical infection of this section is the ongoing pandemic of El Tor cholera which began in 1961, and which continues to spread by the symbiotic combina­tion of a symptomless carrier state and wide-scale travel.

 

 


» Poliomyelitis
» Infective Hepatitis
» Typhoid (Enteric) fevers
» Non-specific Gastroenteritis
» Cholera
» Enteritic Necroticans (Pigbel)
» Melioidosis
» Leptospirosis
» Protozoal infections
» Amoebiasis
» Giardiasis
» Coccidial infections
» Toxoplasmosis
» Balantiasis
» Trichinosis
» Enterobiasis
» Capillariasis
» Anisakiasis
» Gnathostomiasis
» Dracontiasis (Guena Worm Infection)
» Diphyllobothriasis (Fish Tapeworm)
» Sparganosis
» Dipylidium caninum (Dog Tapeworm)
» Hymenolepis nana (Dwarf Tapeworm)
» Hymenolepis diminuta (Rat Tapeworm)
» Taenia solium (Pork Tapeworm)
» Taenia saginata
» Hydatidosis
» Linguatula serrata (Tongue Worm)
» Other Pentastomids


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