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List of three major diseases caused due to fungi in animals. The diseases are: 1. Epizootic Lymphangitis 2. Ringworm (Dermatomycosis) 3. Aspergillosis.
Disease # 1. Epizootic Lymphangitis:
Definition:
This is a chronic disease of horses caused by a fungus Histoplasma (Crypto- coccus) farciminosus and characterised by inflammation and suppuration of the cutaneous and subcutaneous lymphatic vessels and glands.
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Animals susceptible:
Chiefly horses, mules and donkeys but cases have been recorded in cattle.
Modes of infection:
It gains entry through a wound or abrasion either on the skin or of a mucous surface. The disease is spread by harness, grooming tools etc. which have come in contact with diseased animals. The parasite shows considerable vitality outside the animal body.
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Incubation period:
It is usually a matter of weeks or months (average 6 to 8 weeks) and the spread of disease is slow and insidious. Even by means of experimental inoculation, incubation takes one month.
Symptoms:
The first signs of the disease are often thickening or “Cording” of a lymphatic vessel and adjacent gland. The lesions start from a wound or abrasion on any part of the body, the commonest site being the legs. The first sign noted is nodules up to a size of a walnut along the lymphatic vessels leading from the site of infection which, as the disease progresses, suppurate. The lymph glands into which the vessel drains swell and often develop large abscesses.
These abscesses and suppurated nodules referred to above ultimately burst—discharging creamy white or faintly yellow thick pus. Later on, these areas turn into ulcers with a red granulating base which have little tendency to heal. The forelimb—from the shoulder to the knee—is perhaps the usual site. Tumour-like masses may be seen at the shoulder and a thick cord may run down the limb. The larger masses may not burst at all if left alone.
When a limb is affected, it shows considerable thickening from chronic lymphangitis.
The characteristic feature of the disease is that the affected animal presents no constitutional disturbance even when extensive lesions are present.
Diagnosis (Differential):
This disease may be confused for Farcy. In this disease, the pus is thick and creamy, on examination of which Histoplasma (Cryptococcus) farciminosus is demonstrable; whereas in Farcy, the pus is yellowish grey, viscid, occasionally reddish and is oily in appearance. Besides, there is the Mallein test to differentiate Farcy from Epizootic lymphangitis.
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Treatment:
Benign cases may heal spontaneously but malignant cases resist all forms of treatment. In general, exposure to direct sunlight, dry air, good feeding with much nitrogenous food and rest have a favourable influence on the disease and this explains why in tropical and subtropical regions, recovery is’ more frequent than in other countries.
Treatment consists in surgical excision of all affected nodes, cords and ulcers with antiseptic dressing. Ulcers treated locally with a.2% methylene blue solution hastens their healing.
Injection of the following is reported to have excellent results:
This is given intravenously once a day for 8 days and after a gap of one week for another 8 days.
Disease # 2. Ringworm (Dermatomycosis):
This is a parasitic skin disease of man and animals of a contagious nature and is caused by the fungi belonging to the genera Microsporon and Trichophyton. The organisms belong to the two genera of fungi Imperfecti, a large group of fungi whose life history is not completely known.
Incidence:
It occurs in all animals. It is commonest in cattle, occurring chiefly in calves.
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Then—in order of susceptibility — horses, dogs, cats, pigs and sheep.
The young ones in all species are more susceptible because of their finer skin, the same applying to fine skin breeds irrespective of age.
Infection may spread from one species to another and to man by direct contacts or indirectly through infected articles.
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Predisposing causes:
It must be remembered that two important contributory causes of ringworm are:
(1) Over-crowding of animals into unhygienic, badly ventilated buildings and
(2) General debility due to under-nourishment. There is of course seasonal variation.
Symptoms:
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At the commencement, rounded areas without hairs or with stumps of broken hairs are seen. The first manifestation of ringworm is that the skin becomes reddened or inflamed and a little whitish, greyish or yellow serum exudes from its surface and little nodule or vesicle form at each follicle. As a result, greyish or yellowish scales and later thick crusts or scabs form over, the areas, with subsequent development of suppurating surface under them, which, in course of time, causes these crusts to become loose and fall off.
These areas heal with new hairs growing over them. Sometimes, the lesions coalesce to form large irregular-shaped areas. New patches appear and repeat the process. Itching is most pronounced during the initial and terminal stages.
The lesions with crust formation is most common in cattle and in case of horses and other animals, the patches are usually scaly or have a scab.
In cattle:
This is due to Trichophyton verrucosum infection. The lesions are nearly always on the head and neck, rarely on the body. Specially the eyelids, lips, ears and above the jaw are affected. The lesions begin as a raised ring-like patch on which the hairs stand erect. In a short time, the hairs fall off and the surface of the skin becomes covered with masses of scales heaped up into greyish-yellow crust. In calves, round the mouth and above the eyes, infection having taken place from the mother.
In horses:
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The infection is due to either Trichophyton or Microsporum. The lesions occur on the shoulder, back and flanks. The lesions occur in regular circles and seldom with any pruritis. The hair becomes matted in patches and this gradually extends until the whole area is denuded. The skin becomes raised and greyish white crusts are formed.
In dogs:
The infection is caused by four varieties — Trichophyton, Microsporum, Oidmella or Oospora. The lesions are most on head and limbs. These occur in circular patches which become denuded of hairs and later covered with loose crusts or scabs.
In cats:
Infection is due to Trichophyton, Microsporum and Achorion.
The lesions are similar to what are seen in other animals.
Treatment:
Oral administration of Griseofulvin is the best and simplest method. Hard crusts must be softened and removed before applying the remedy. For softening, equal parts of soft soap and lard are best which is applied with rubbing and left over for 2 to 4 days, with repetition if necessary. Addition of little quantity of Pot. carbonate to the above expedites the softening.
Antiparasitic remedies such as Acid Salicyl, Resorcin, Coal tar, Napthalene, Creosote etc. in an ointment form is to be applied after cleaning as suggested above.
N. B.:
The fungi are known to be sensitive to oil and fat, hence, antiparasitic remedies should have oil or fat base.
In cases in which the lesions are not extensive, good results are obtained by application of the following:
Part of Iodine in 1 to 5 parts of alcohol or Xylol. Since this remedy is irritating, it must be used with care.
Several antifungal ointments are now available and can be used safely without causing any irritation.
Disease # 3. Aspergillosis:
Definition:
This is a disease of mammals and birds produced by the growth of the fungus Aspergillus in the tissues of the body. The most commonly affected is the respiratory tract but it has also been seen in ears, mouth, throat and liver. It runs a slow course and often mistaken for tuberculosis.
Etiology:
The disease is produced by fungus Aspergillis where it causes a necrosis or death of cells and formation of small abscesses. Within the body, they grow out hyphae and produce more spores and these spread the infection further.
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Symptoms:
In cattle:
The animal appears dull and weak and the appetite is poor. There is no rise of temperature. The disease resembles contagious pleuro pneumonia or tuberculosis but symptoms are not characteristic. The breathing is difficult and often accompanied by a dry cough. The animal does not thrive. The nasal discharge contains fungus or its spores.
In horse:
The disease is not common. It is manifested by sore throat, bronchitis, pneumonia, according to the seat of fungus. It may resemble anthrax or anaemia.
In dogs:
Normally the animal contracts the infection from poultry. It is manifested by epileptic-form convulsions or symptoms that are not unlike those of rabies. There is severe scratching or rubbing of the muzzle and there is discharge from nostrils which may be blood-stained. The disease runs a rapid course. Almost all the cases have occurred in the nasal cavities.
In poultry:
The air passages become filled with cheesy material in which the fungus develops and breathing becomes extremely difficult. The bird gapes with its beak and gasps. Frequent sneezing and coughing are noticed. The sick bird remain isolated from the rest of the flock and there may be diarrhoea. A discharge with a repulsive odour trickles from the mouth and nostrils.
Treatment:
There is no specific treatment and very unsatisfactory. Local infusions of Nystatin may be tried in case of valuable animals.
