VPE 511: Environment and Environmental Hygiene (2+1)

Organisms occuring to excreta

ORGANISMS OCCUR TO EXCRETA

• Organisms pathogenic to livestock occur in animal excreta. Some are excreted in the droppings or urine of diseases or carrier animals. Eg swine fever flies use the faeces as sutiable breeding material. The mycobactrous peratuberculosis remain viable for bovius faece as long as 246 days.
• The anthrax bacillus is another micro organisms which occurs in the excreta and to carrier eatening animal and birds of prey, considered as potential dissemenatures of infection particularly in hot climate when flies are abdunent.
• Amongest other bacteria which occur in excreta and may cause disease are organisms belonging to the clostridium and salmonella group.
• Of the protozoa which are excreted in faeces, coccidia are important in the production of disease amongst both animal and birds. Owing to the resistant nature of the oocysts especially when sproulated they not only remain alive for periods of many months but are difficult to destroy by most chemical disinfectants.
• Numerous helminths occur in the droppings of livestock mostly in the egg stage but a few as larvae and may transmitted from the diseased to the healthy animal by contaminated food or water which contains the infective stages of the worms. The red worm of strongyles of horses, the lung worm of cattle dictyocaulus viviparous, habronema species of horses which use house fillies and stable flies as recturns.
• Organisms which use faeces as breeding material are precipally insects particularly flies. They are mostly important in playering the role of disseminators of diseases producing organisms.
• The pathogens found in faeces may also be carried on the clothing and footwear of persons whose business is to remove faeces another from sheds and stables. They may contaminate food stuff as for example when doing is distributed over land when green crops are being raised for animal food. Birds may to some extent be responsible for disseminating pathogenic organisms service some species frequent manure heaps in search of seeds and insects and in doing so pick up infective material on their feet and legs and convey it else where.

Manure as a breeding material for flies

• Of the flies which select manure as a breeding material the most important is the house fly musca domestica and somoxys calicitrans commonly known as the stable fly or biting house fly. Horse , pig and to a lesser extent cattle doing appears to bethe most favoural materials in which these species and flies breed. The flies oviposits only in material which can provide food in a readily assemilable form, suffered moisture and usually warmth and shelter for the developing maggots.
• The fly also breed in decaying and fermenting organic matter of various kinds and in poultury droppings. It does not breed in cow dung scattered in fields. Although horse manure is the chief breeding site this material is attractive to oviposting house flies only so long as it is and not much older than twenty for hours.
• The stomoxys calcitrans deposits its eggs in moist decaying vegetable matter shown as piles of waste litter and find stuffs that may collect in a farm yard, get wet and decay as are with urine or have certain amount of manure added to them.
• The flies in great numbers may result in epidemics of typhoid fever and other disease. The whole life cycle of muscle domestic can be completed under very favourable circumstances in 8-9 drop. The rate of development rares greatly depending upon the temperature of the air and of the feval material and upon the nature of the ford and other factors. The eggs are deposited in small matter of 120-150 in cervices below the surface of the manure. After housefly may deposit five or six such batches during her life time and may produce in all for 60 to 900 or more eggs. The maggots avoid light and burrow into and feed upon their food material. They do not to have occur throughout a manure heap but are usually restricted to the superficial layer, at the most from 10 to 12cm deep, because the head produced by fermentation makes t impossible for them to love it deeper levels. To pupate the maggot leaves the manure heap to find a drier and cooler place outside the base of the heap her which to undergo its metamorphosis.