Anthrax in animals

What is Anthrax?
Anthrax is an acute, contagious disease chiefly of livestock that occurs through out the globe and is characterized by septicemia. It is a zoonotic disease and so man can get the infection from infected animal. Anthrax is also known as Splenic fever, Wool sorter’s disease, Charbon and Milzbrand. Anthrax is caused by Bacillus anthracis. The disease was recorded in 1836 and it is one of the oldest recorded diseases which is world wide in distribution. Anthrax is a popular disease because terrorist used the anthrax spore to spread disease and so is an an effective weapon for terrorists as a biological weapon.

What is Bacillus anthracis?
Bacillus anthracis is a gram positive, spore bearing, large rod shaped non- motile aerobic organism . The size of Bacillus anthracis is 4-8 µm in length by 1-1.5 µm in width. Under favourable condition anthrax spores develop into bacilli and each spore give rise to one bacillus. The optimum temperature for growth of bacilli is 35-37°C although growth can occour within a range of 12-44°C. Under aerobic condition sporulation of anthrax spore takes place within a temperature range of about 15-40°C and optimally within temperature of 25-30°C.

Which animals suffers from anthrax?
Anthrax occours in cattle, sheep, goat , horse, pig. Anthrax has been occasionally recorded in dogs, tigers and poultry. The most suspectible animals are cattle and sheep and next is horse and pig. Anthrax has been reported in elephants of India, Burma, Tanzania and Siam. No mammals have absolute natural immunity against anthrax.

What is the incubation period of anthrax?
The incubation period for anthrax
is 1-14 days. When transmitted by biting flies it may be 24-48 hours. Spores can remain viable in the soil as long as 15 years.

How does anthrax spread among animals?
Once anthrax spore is ingested or placed in an open cut it develops into bacilli and begins multiplying inside the animal or human body. Anthrax spores have got the ability to live in the soil for many years and thus remain as a continous source of infection. The flood, streams and rivers may carry anthrax spore from one place to another and thus contaminate the soil. Wild and domestic animals can get the infection through this soil. Ingestion of feed contaminated by anthrax spore like meat, bone meal and offal’s may also serve as a source of infection.
Anthrax can be mechanically transmitted through inoculation by biting flies and mosquitoes. Live spore may become vegetative spores in some animals following vaccination and cause the disease if vaccine is not properly attenuated.
Butchers, veterinarians, tanners, skinners, meat inspectors are more susceptible to anthrax in man. Humans can become infected when the anthrax spore enters via cut injuries or abrasions while handling infected meat. Inhalation of anthrax spores from infected animal products such as wool is another way of transmission. People also get infection by eating undercooked meat from infected animals.

What are the signs and symptoms of anthrax in animals?
Signs and symptoms of anthrax in different animals are as follows
Cattle and buffalo: Anthrax occurs in acute and sub-acute form in cattle and buffalo
1.Acute form: Death occurs in outbreak proportion in acute form of anthrax and this form is predominantly found in cattle. The signs and symptoms are as follows
(a) High body temperature of about 104-108°C.
(b) Rapid and deep respiration, increase heart rate
(c) Depression, animal refuses to eat, bloat
(d) Muscle tremor with the advancement of disease
(e) Extreme aggressiveness following depression
(f) Distressed breathing at the end at the end
(g) Mouth breathing due to oxygen hunger
There is oozing of blood from natural orifices following death. Animal may be found dead without any premonitory signs and dead usually occurs within 48 hours.

2.Sub-acute form: Course of disease runs from few weeks to months with varied clinical symptoms of oedema under the neck, brisket region, thorax abdomen and flank. In teminal stage of the disease terminal pulse is seen. Pregnant cattle may abort and some may survive for 2 to 3 months.

Sheep and goat: Per-acute form of anthrax occurs in sheep and goat. There is increase in body temperature, animal refuses to eat, depression. Subcutaneous edema is found.
Sudden dead occours which is characteristic in nature. But in some cases dead is preceded by staggering gait, trembling of the body, vertigo, grinding of teeth and laboured breathing. Dead occurs rapidly after convulsion.

Horses: Per-acute, acute form, sub-acute form of anthrax occurs in horses.
In per-acute form horses die suddenly without showing any clinical manifestation. Horses die suddenly in the stable or grazing field. Acute form of anthrax in horses is characterized by increase body temperature, respiratory distress and rapid pulse ratem. Hyperemic or cyanotic changes may be seen in the mucous membrane. There are also symptoms of colic with passage of bloody faeces. Staggering signs appear with spasm of the limbs. Dead occurs within 5-10 hours following attack.
In sub-acute form of anthrax oedematous swellings on the lower part of throat, neck, shoulders and abdomen. Intermittent colic with signs of abdominal respiration is seen. Course of disease may run for 3 months. Oedema of the cutis and sub cutis with formation of carbuncles may be noticed in local form of anthrax. These carbuncles are found on the neck, abdomen, chest and limbs.

Pigs: Either acute or sub-acute form of anthrax occurs in pigs. Oedema of pharynx and lower part of neck with swollen lymph node in the neck region is seen. Because of this normal respiration and deglutition may be interfered. Redness of visible mucous membrane with haemorrhagic spots of various size are found scattered over the skin surface. Rarely enteritis with diarrhoea may be seen. Usually the symptoms are chronic in nature because pigs have natural resistance to anthrax than most herbivores. Anthrax is not always fatal in pigs.

Dogs: Anthrax seldom occurs in dogs and other carnivores animals and it usually occurs following ingestion of infected meat and blood. Usually per-acute signs are seen in dogs. Dullness, anorexia, increase body temperature with inflammation and swelling of throat and lymph nodes may be seen. Carbunculous ulcer may be seen on the tongue, lips and foot pads. In dog bleeding from natural orifices is not seen as in other animals.

What are the signs and symptoms of anthrax in man?
In man three form of anthrax is seen. They are as follows
(a) Cutaneous anthrax: In the skin initially there is a small, raised bump which develops into fluid filled blisters and within 7 to 10 days it develops into a painless ulcer with black centre. This usually appears on the face, arms or hands. Headache, Fever and swollen lymph node near the blister area occurs.
(b) Inhalation anthrax: Man suffers from fever which may be accompanied by chills or night sweats., sore throat, chest discomfort cough, sore throat, shortness of breath, meningitis, shock and dead after 1-2 days following acute symptoms.
(c) Gastro intestional anthrax: Due to ingestion of anthrax infected meat there is diarrhoea, abdominal pain, dehydration, inflammed intestional tract. The bacteria invades the bowel system and it speads throughout the body through the blood stream and so toxins develop.

Diagnosis of anthrax:
Diagnosis of anthrax is done by the following ways:
Clinical signs- Bloody discharges from the natural orifices like mouth, nostril, anus
Laboratory examinations: The various laboratory examinations are as follows
(a) Microscope examination of stained blood film- Films of thick blood on glass slides, dried in air, fixed slightly in heat and stained with polychrome methylene blue or Giemsa’s stain is washed in water, dried, and examined under oil immersion microscope. If positive, Polychrome methylene blue will show a pink capsule around large square ended blue rods in short chain known as McFadyean’s reaction. The Giemsa stained smear will show reddish discoluration of capsules.
(b) Cultural examination: Suspected blood sample is streaked with an inoculating loop on 5% blood agar and nutient agar plates and the plates are incubated periodically for 28-24 hours at 37°C. Smears of coloniesare made and stained with Giemsa and observed under microscope. In positive cases, cultural characteristics of Bacillus anthracis like very little or no haemolysis, absence of motility, medusa head appearance and inverted fur tree appearance on gelatine stab culture is seen.
(c) Animal inoculation- Mice or guinea pig are preferred for inoculation. Suspension with quantity of sterile normal saline from materials like blood from ear or swab of blood stained discharges is made and heated at 60°C for 30 minutes. 0.5 ml of the suspension is injected in the thigh of pig subcutaneously. If positive it will die within 36-40 hours.
(d) Vesicular fluid from human leision- With the aid of sterile pasteur pipette, fluids are obtained from cutaneous leision of the hand having malignant vesicles. The fluid sample may be streaked upon 5% sheep blood and nutrient agar.
(e) Serological test (Ascoli’s test)- Hide or tissue is boiled in watter and its extract is obtained. The clear fluid is obtained which is layered on a very narrow precipitating serum. In positive cases whitish ring appear at the junction of the two fluids.
(f) Serodiagnosis- Enzyme-linked immunosorbent assay ( ELISA) using purified antigen of Bacillus anthracis is used and molecular diagnaosis by Polymerase chain reaction (PCR)

Treatment of anthrax in animals:
If the cases are attended at the early stage of the disease treatment is effective.
(a) Antibiotics- Anthrax bacilli are sensitive to Streptomycin, Penicillin. and Oxytetracycline and other broad spectrum antibiotics. In cattle, Penicillin 10,000 units/kg body weight twice daily twice daily for 5 ys

Streptomycin 8-10gm/day twice daily for 5 days
Oxytetracycline 5mg/kg bwt daily for 5-10 days
(b) Antiserum(with Ab)- Anthrax antiserum called hyper immune serum 100-200cc through i/v route

How to prevent of anthrax in animals
Anthrax is prevented in animals by the following ways
(a) Prevent introduction of infected animals to areas free from anthrax
(b) Quarantine measures should be taken in anthrax prone areas.
(c) Use fly repellant to minimize flies and mosquitoes population.
(d) Deep burial of the dead body with quick lime
(e) Do not contaminate the pasture by opening the carcass in the open.
(e) Fodder from infected pasture should not be given to animals.
(f) Vaccination- Vaccine used are

Pasteur vaccine – First inject vaccine 1 and then inject vaccine II after 10-12 days.
Spore vaccine- 1 ml in cattle, horse,sheep and goat. In elephants a second dose of 3 ml is given after the first dose of 1 ml
Sterne vaccine- can be given in all animals
3% per acetic acid or 10% caustic soda or 10% formalin can be used to disinfect the adjacent areas of the dead and infected animals. 3% per acetic acid can kill the spore and can be applied on the soil to kill the environment.

How to prevent anthrax in man?
Anthrax is prevented in man by the following ways
(a) Eating meat that hasn't been properly cooked must be avoided in countries where anthrax is common.
(b) Educate butchers, tanners, skinners and those working in infected articles.
(c) Sterilize hair, hides, bone meal, wool prior to processing with ethylene oxide gas or ionizing (gamma) radiations.
(d) Incinerate infected animal products.
(e) Penicillin is the drug of choice but if it is contraindicated then Chloramphenicol, tetracycline, erythromycin, ciprofloxacin can be used.
(f) Vaccination should be done specially for military personnel, butchers, tanners, skinners and laboratory workers.


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