Coccidioidomycosis in Chicken Pullets in Jos, Plateau State, Nigeria: A Case Report

Abstract

Coccidioidomycosis is a dust-borne infection caused by a dimorphic fungus Coccidioides immitis and is known to occur in man and a wide variety of wild and domesticated animals including deers, mice, rats, monkeys, dogs, cattle, and horses, but have not been shown to infect birds (Merck Veterinary Manual, 1998; Saubolle et al., 2007). The organism grows well in cultures with recovery rate of 0.4%, 2.6% and 8.3% respectively for blood, bone marrow and respiratory tract cultures respectively (Saubolle et al., 2007). They produce aerial mycelia which form a small, fluffy-white, spherical colony; in tissues the fungus takes the form of spherules (sporangia) 20-80 µm with double contoured walls (Jones et al., 1997; Kaufman and Standard, 1987). The disease occurs mainly in the Americas where farmers and others who work with soil are most likely to inhale the spores and become infected. Coccidioidomycosis in animals usually assumes the chronic progressive form with primary lesions in the lungs and disseminate initially into regional lymph nodes, then to almost any internal organ within the chest or abdomen. In some species like the dog and monkey, lesions may be disseminated throughout the skeletal system and also present with ocular involvement (Jones et al., 1997; Shubitz, 2007). Generalized infection usually runs a slow course; the signs are non specific and may include ernaciation, in appetence low-grade fever and occasional cough. The gross lesions of coccidioidomycosis resemble those of tuberculosis in many respects; they appear as discrete or confluent granulomas with or without suppuration or caldification, in the disseminated form of the disease, grayish nodules of various sizes may be found in the lungs, lymph nodes, liver, spleen and other organs (Bharucha et. al., 1996; Merck Veterinary Manual, 1998). The nodules are usually irregular in shape and many exude material when squeezed. The microscopic appearance is characteristic, but varies to some extent in relationship to the developmental stage of the fungus; however, Kaufman et al. (1998) described some unusual morphologic forms of this organism in biopsy tissues taken from the lungs of a human patient. The spherules are often filled with endospores (sporangiospores) 2-Sum in diameter and have wide zone of epithelial cells admixed with a few neutrophils and some lymphocytes. When the wall of a spherule ruptures, it releases a lot of endospores and the surrounding tissues express reactions that are rich in neutrophils and lymphocytes with few epithelioid cells (Saoubelle, 2007). The organisms within the cytoplasm of Langhans' giant cells are clearly seen in sections stained with hematoxylin and eosin. In the liver, spleen and lungs, the lesions are usually spherical and sharply circumscribed and expand to displace normal issues (Jones et al., 1997; Merck Veterinary Manual, 1998). Microscopic demonstration of the organism (typical mature spherules filled with endospores or arthroconidia) in characteristic lesions is diagnostic. In this report, the first recorded case of coccidioidomycosis in chickens in Nigeria diagnosed by postmortem analysis at the National Veterinary Research Institute, (NVRI) Vom Plateau State, Nigeria and confirmed by histopathology of lung tissues at the National Institute of Animal Health (NIAH), Tsukuba, Ibaraki Prefecture, Japan is presented.