Continued from page 3Bacterial Diseases
General
Neuromuscular disease signs may be seen secondary to bacterial septacemia from a multitude of different organisms. Sepsis should be included on the differential diagnosis list in particularly those cases with polyarthritis, encephalitis, ataxia, blindness or acute inability to stand.
Clostridium spp.
Key points: Botulinsm is not recognized in the United States yet; limberneck and clinical signs similar to that of poultry and waterfowl species. Maggot consumption incriminated in botulism. Black leg documented in an emu juvenile, with cavitation, hemorrhage and necrosis of affected leg muscles noted.
Botulism (Clostridium botulinum) has been reported in ostriches that were allowed to consume maggots from a decomposing carcass. The clinical signs noted were similar to that of waterfowl, including weakness, ataxia and a loss of cervical neck muscle strength, producing "Limber Neck" signs. Botulism has historically been recognized in South Africa as a significant industry problem in adult ostriches.
Black leg (Clostridium shovaei ) has been reported in a six month old emu. The clinical manifestation of disease was described as paralytic, with cavitation, hemorrhage and necrosis of affected muscle noted at necropsy.
Mycoplasma
Key points: Only M. synoviae has been documented associated with disease including lameness and bilateral swelling of the feet and hocks.
Mycoplasma synovae was associated with infectious synovitis in an emu. The diagnosis of MS was made by detection of mycoplasma-like organisms in synovial fluid of an eight year old emu. Clinical signs included lameness with bilateral swelling of the hock joints and feet. The organisms reacted with Mycoplasma synoviae but not with Mycoplasma gallisepticum immunofluorescent reagent.
Tuberculosis
Key points: Muscular wasting, weakness and cachexia; zoonotic potential, possible skin testing as a flock screening tool.
Mycobacterium avium infection has been described in emus and ostriches. Muscular wasting and general cachexia, the general hallmark of this disease, were significant clinical signs noted. Extensive granuloma formation was observed in these cases at necropsy. Diagnosis was established by the demonstration of acid fast bacilli in lesions and the culture of M. avium from liver tissue. Positive skin reactions were noted in exposed emus on the same farm, suggesting that skin testing may be one approach to screening these flocks.
Fungal Diseases
Key points: Secondary neuromuscular signs may include cachexia and muscle mass depletion.
Aspergillus is reported to cause rhinitis/sinusitis and pneumonia in ratite species. Candida is seen associated with enteritis and malabsorbtion related problems in the ostrich. Rhizopus oryzae was isolated from the ventriculus of ostriches demonstrating anorexia, progressive stunting and stomach impaction after treatment with antibiotics. Proventricular zygomycosis is characterized by massive accumulation of a clear white gelatinous mucus adherent to the inner surface of the ventriculus plus a severe necrosis of the glandular layer of the proventriculus. Cryptococcus has been incriminated in pneumonia in the ostrich.
The significant neuromuscular manifestaion of these fungal diseases was general cachexia and wasting. Aspergillosis and most other fungal diseases in general are believed to represent a ventilation or other related management problem.
Parasitic Diseases
Wireworm
Key points: Produces proventricular disease; secondary neuromuscular signs include cachexia, loss of muscle mass and weakness; diagnosis may be challenging, as ova appear similar to those of the harmless cecal worm.
The wireworm Libyostrongylus douglassi is an economically important parasite of the ostrich. This parasite has been recognized in the United States as well, and should not be discounted from consideration when aproaching individual or flock problems with general signs inclusive of this disease. Adults, third and fourth stage larvae reside in the glandular crypts of the proventriculus, producing a gastritis which inhibits digestion. Cachexia and generalized muscle wasting are hallmark clinical signs. The South African term used to describe disease attributable to wireworm is Vrootmaag, meaning "stomach rot". This name was used to describe the malodorous and severe proventriculitis associated with this parasitic disease. Diagnosis is made by identification of the trichostrongylid-type egg in the feces. These eggs can be confused with the harmless cecal worm, Codiostomum struthionis. Fenbendazole(15 mg/kg), Levamisole(30 mg/kg) and Ivermectin(0.2 mg/kg) are considered effective therapies.
Chandlerella
Key points: Reported as an emu specific disease at present time; endemically carried asymptomatically in the lateral ventricles of the Grackle; regional to the south and southeastern United States; neuromuscular signs may include torticollis, ataxia, and abnormal gait; vector control (mosquito) and preventative ivermectin treatment may be helpful.
The filarid nematode, Chandlerella quiscali was found in the spinal cord and lateral ventricles of the brain of emus with clinical signs including torticollis, ataxia and abnormal gait followed by recumbency and death. Two to five month old birds seemed to be affected, with adults and yearlings apparently resistant. Circulating microfilaria were never demonstrated in effected birds. Grackles are the normal host for C. quiscali, which is transmitted byCulicoides sp mosquitoes. Prevention may be possible by vector control, elimination of the environmental conditions that are conducive to transmission and treatment to prevent larval migration. It is theorized that the reported outbreak of this parasitic disease was triggered by a shift in environmental and host interactive factors, as no significant problems have been encountered since then, and not all birds in the recognized endemic areas are being treated prophylactically. Ivermectin at 0.2 mg/kg administered subcutaneously at four week intervals appeared to prevent clinical signs in flocks in the presumed endemic area. Treatment after clinical signs are noted should be expected to be of marginal benefit.
Baylisascaris
Key points: Recognized in all ratite species; neuromuscular signs may include ataxia, loss of equilibrium, circling, staggering, walking backwards and inability to stand or walk at all.
Baylisascaris procyonis is reported as a cause of cerebrospinal nematodiasis in the ostrich and emu, and is believed to be a potential problem in rheas and cassowaries as well. Clinical signs that have been noted include: progressive neurologic disease, loss of equilibrium and balance, progressive ataxia, circling, staggering, walking backwards and ultimately inability to stand or walk. At necropsy, birds may show extensive multifocal encephalomalacia and inflammation of the brain stem and cerebellum associated with larva of Baylisascaris procyonis. Baylisascaris is a common roundworm of the raccoon. Infected raccoons shed an average of 20,000 eggs per gram of feces. These eggs can survive for extended periods; up to several years in soil, cages and enclosures.In one reported case, the bird's pen was heavily contaminated with raccoon feces. Prevention is accomplished by avoidance of parasite eggs. This may specifically be through de-worming resident raccoons and skunks routinely and monitoring their fecal egg counts and keeping them housed away from other susceptible species. Feral or wild raccoons should be removed from the location that the birds are housed. Heat is known to kill the roundworm eggs best, although boiling water, steam, autoclave or propane flame gun may be efficacious. Unfortunately, most of these measures are relatively impractical for use in routine ratite management. Removal of contaminated dirt in contaminated enclosures may be helpful.
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