Coccidioidomycosis, Biology

Assignment Help:

Coccidioidomycosis


Coccidioidomycosis is a soil-borne infection of pet, domestic, wild animals and  man. The disease is caused by Coccidioides immitis, a dimorphic fungus which occurs commonly in the soil as saprobe. The fungus is extremely virulent. The fungus has a environmental or saprobic form and a parasitic form in the tissues. The infection is usually localized and benign, but may sometimes become disseminated and fatal. Both humans and animals acquire the infection by inhalation of infective arthoconidia. The affinity for the lung tissue is strong. In some cases haematogenus or lymphatic dissemination results in infection of the bone, skin, lymph nodes, and central nervous system.


Symptoms: The affected dog shows fever, dyspnoea, acute or chronic cough, gradual emaciation, difficulty in walking and intermittent diarrhoea. The infection in cattle and pig is usually benign. The diagnosis is made either at necropsy or in abattoir. The lungs, and bronchial, mediastinal, mesenteric and pharyngeal lymphnodes are commonly involved. They show granulomatous lesions which contain cream-coloured pus. Fever and abscesses in peripheral lymphnodes are observed in sheep. The clinical signs in horse include fluctuating temperature, oedema of legs, severe weakness, intermittent colic, anaemia and leucocytosis. The death occurs due to rupture of liver. The dissemination of infection seems to be common in dogs than in cattle.


Diagnosis:
Diagnosis is confirmed on culture, histopathologic or molecular evidence of the presence of fungus. The Gomori methanamine silver or periodic-acid-Schiff (PAS) stained sections show thick-walled spherules (20-10 um in diameter) containing many small globose endospores (2-5 u in diameter). Direct microscopical examination of smear from abscess or spinal fluid by wet mount in saline containing 10% KOH for spherules also helps in diagnosis. Thick-walled, barrel-shaped arthrospores appear alternatively in chains, separated by empty (disjunctor) cells. The fungus may be isolated from exudate or tissues on Sabouraud‘s medium with cycloheximide- chloramphenicol agar or brain heart infusion agar. The causative organism appears in the tissues as a round, doubly walled structures called the spherule. The host generates cutaneous delayed-type hypersensitivity reaction to intradermal inoculation of test c o c c id io id in (sup e r na ta nts o f myce lia l  Co c cid io ide s b r o th c ultur e  la rge ly polysaccharide containing some amino acid nitrogen). This skin test is also employed for diagnostic; however, it is more useful in epidemiological survey. Several tests like immunodiffusion, complement-fixation, enzyme immunoassay, latex agglutination, ELISA can detect circulating antibodies in serum or cerebrospinal fluid after 2-4 weeks post-infection. Animal pathogenicity tests are conducted in mice and guinea-pigs.


Treatment and prevention:
Since the mild or benign form of the disease is self- limiting, no therapy is required. However, in progressive and disseminated cases Amphotericin-B and Saramycetin may be used. Ketoconazole remains the drug of choice in veterinary medicine. Live attenuated and killed vaccines are also tried in animals with variable success although vaccines are not available.


Related Discussions:- Coccidioidomycosis

Explain the cladosporium - fungi and yeast, Explain the Cladosporium - Fung...

Explain the Cladosporium - Fungi and Yeast? Classification Kingdom - Mycetae Division - Amastigomycota Form - Class - Deauteromycetes Form - Order - Moniliales F

Spirochetosis (tick fever), S p ir ochetosis (tick fever) This is di...

S p ir ochetosis (tick fever) This is disease of young birds under poor management mostly reared as backyard poultry caused by a spiral bacterium, Borrelia anserina and tr

Explain about post-operative pain, Post-operative pain  There is some d...

Post-operative pain  There is some discomfort for about 24-48 hours. Persistent pain for a longer duration, with swelling, may indicate possible infection around the implant an

Define the buffer capacity - nutritional biochemistry, Define the Buffer ca...

Define the Buffer capacity - Nutritional Biochemistry? Buffer capacity can be defined as, 'the capacity of a solution to resist changes in pH on the addition of strong acid or

Locomotion in protozoa, give a detail account of modes of locomotion in pro...

give a detail account of modes of locomotion in protozoa

What do you mean by neuronal repolarization, Q. In chemical terms how is th...

Q. In chemical terms how is the neuronal repolarization achieved? Repolarization is the return of the membrane probable from the action potential (+35 mV) to the resting potent

Explain an open circulatory system, Why, even though they have an open circ...

Why, even though they have an open circulatory system, can flying insects like flies beat their wings with great speed? In insects the circulatory system is open but this syste

Explain about the anorexia nervosa, Explain about the Anorexia Nervosa? ...

Explain about the Anorexia Nervosa? Anorexia nervosa, as you have read above, is a psychological eating disorder characterized by somatic delusions that one is too fat despite

What is polygenic inheritance?, What is polygenic inheritance? How does it ...

What is polygenic inheritance? How does it work?  The Polygenic inheritance, also called as quantitative inheritance, is the gene interaction in which a given trait is conditio

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd