Blackleg, black quarter, quarter evil, or quarter ill ( la, gangraena emphysematosa) is an

infectious An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

most commonly caused by ''

Clostridium chauvoei ''Clostridium chauvoei'' is an anaerobic, motile, Gram-positive bacterium. It is a soil-borne pathogen that can cause blackleg in cattle and sheep. It is named after Auguste Chauveau, a French bacteriologist and veterinarian. It is mainly cons ...

'', a

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

bacterial species. It is seen in

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...

all over the world, usually affecting

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...

, and

goats The goat or domestic goat (''Capra hircus'') is a domesticated species of Caprinae, goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a membe ...

. It has been seen occasionally in farmed

bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...

and

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...

. The acute nature of the disease makes successful treatment difficult, and the efficacy of the commonly used

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...

is disputed.

Susceptibility

Most losses due to blackleg occur when the cattle are between the ages of six months and two years, although it can occur when they are as young as two months. Typically, cattle that have a high feed intake and are well-conditioned tend to be the most susceptible to blackleg. Furthermore, many blackleg cases occur during the hot and humid summer months or after a sudden cold period, but cases can occur at any time during the year.

Causative agent

Blackleg is caused by infection with '' Clostridium'' bacteria. The most common causative agent is ''C. chauvoei'', but the disease can also be caused by ''C. septicum'', ''C. sordelli'', and ''C. novyi''.https://www.zoetis.com.au/_locale-assets/faq/faqs-blackleg.pdfhttp://ucanr.edu/sites/UCCE_LR/files/152026.pdf '' C. chauvoei'' is

, rod-shaped,

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

, and

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

, and can produce environmentally persistent

spores In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

when conditions are not ideal for growth. These spores can remain in the soil for years in an inactive state, and return to their

form when consumed by

grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...

livestock.

Contaminated Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Types of contamination ...

pasture is a predominant source of these organisms, which are also found naturally in the

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

of animals.Clostridial diseases: Blackleg. The Merck Veterinary Manual. Available from http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/50704.htm Retrieved 2012-03-20. Cases can occur over many years in areas where soil or manure is contaminated with the bacteria, and it is exceedingly difficult to remove the spores from the environment. ''C. chauvoei'' can produce a large amount of gas as a

metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

byproduct when growing and reproducing, hence the alternate name

gas gangrene Gas gangrene (also known as clostridial myonecrosis and myonecrosis) is a bacterial infection that produces tissue gas in gangrene. This deadly form of gangrene usually is caused by '' Clostridium perfringens'' bacteria. About 1,000 cases of gas ...

, present in humans. This gas builds up in infected tissue, usually large

muscles Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...

, and causes the tissue to make a crackling or popping sound when pressed. Large gas-filled

blisters A blister is a small pocket of body fluid (lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the ...

can also form, which can be extremely painful as they build up in the tissues.

Clinical presentations

When infection begins, the animal may develop a

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

, and the affected limb can feel hot to the touch. The limb usually swells significantly, and the animal can develop

lameness A limp is a type of asymmetric abnormality of the gait. Limping may be caused by pain, weakness, neuromuscular imbalance, or a skeletal deformity. The most common underlying cause of a painful limp is physical trauma; however, in the absen ...

on the affected leg. Crepitation (the sensation of air under the skin) can be noticed in many infections, as the area seems to crackle under pressure.Irsik, M.B. Blackleg in cattle. University of Florida, Institute of Food and Agricultural Sciences. Available from http://edis.ifas.ufl.edu/vm120 . Retrieved 2012-03-22. Once clinical signs develop, the animal may only live a short while, sometimes as few as 12 hours. Occasionally, cattle succumb to the disease without showing any

symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an disease, illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormali ...

, and only a

necropsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any di ...

reveals the cause. During a necropsy, a

diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems engin ...

is usually made very quickly, as the affected muscle is usually mottled with black patches, which are dead tissue, killed by the

toxins A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849–1 ...

the bacteria release when they infect live tissue. If viewed under a

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

, small rod-like bacteria can be seen to confirm the diagnosis.

Vaccination and prevention

The use of a seven-way clostridial vaccination is the most common and cost effective preventative measure taken against blackleg, but its efficacy is disputed. Burning the upper layer of soil to eradicate left-over spores is the best way to stop the spread of blackleg from diseased cattle. Diseased cattle should be isolated. Treatment is generally unrewarding due to the rapid progression of the disease, but

penicillin Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...

is the drug of choice for treatment. Treatment is only effective in the early stages and as a control measure.

References

External links