Plasmodium in Birds Quiz

Atoxoplasmosis

• Affects Passerine birds, such as canaries, finches, sparrows, and starlings
• Has a direct life cycle with an extraintestinal systemic phase
• Canaries can shed oocysts for at least 2 years
• Transmission occurs through the fecal-oral route, via ingestion of oocysts in droppings from infected birds

Clinical Signs

• Listlessness
• Diarrhea and anorexia
• High mortality rate (up to 80%) in young birds
• Enlarged liver, often visible through the abdominal wall
• Hepatomegaly and splenomegaly in acutely affected young birds, often with multifocal necrosis

Pathological Characteristics

• High number of parasites infecting mononuclear cells in blood smears and organ smears
• Parasites are pale-staining, non-pigmented, oval, and intracytoplasmic bodies within the indentation of the cell nucleus
• Nearly spherical oocysts are present in droppings of affected canaries

Diagnosis and Differential Diagnosis

• Difficult to diagnose in chronically infected older birds, as only a few parasites are present in blood and tissues
• Must be distinguished from Isospora canaria, which has slightly larger and more oval oocysts

Haemoproteus Infection

• Fatal infections can occur due to extensive widespread necrosis accompanying the development of large exoerythrocytic megaloschizonts in muscle, heart, liver, and lung
• Presence of large, pigmented gametocytes in mature RBCs that often partially or completely encircle the nucleus without schizogony
• Sudden death without clinical signs or a prolonged course of weakness, lameness, dyspnea, lethargy, poor growth, and anemia may be seen
• Measures to control invertebrate hosts, such as H. columbae, are necessary

Leucocytozoonosis

• Infection can range from subclinical to fatal
• Mortality may approach 100%, but can vary
• Acute outbreaks of leucocytozoonosis have been reported in chickens, turkeys, and waterfowl
• Species in domestic birds include L. simondi, L. smithi, L. caulleryi, and L. schoutedeni

Plasmodium

• Plasmodium spp. often infect a wide variety of domestic and wild birds in most areas of the world and can cause losses
• Invertebrate hosts include ornithophilic mosquitoes, such as Culex, Culiseta, or Aedes spp.
• Clinical findings, lesions, and diagnosis may include weakness, lassitude, dyspnea, anemia, abdominal distention, ocular hemorrhage, and death
• Death results from blockage of capillaries in the brain or other vital organs by exoerythrocytic schizonts in endothelial cells
• Liver and spleen are markedly enlarged and often discolored (dark brown to black)

Treatment

• Chemotherapy is variably effective, but chloroquine (5-10 mg/kg) potentiated with primaquine (0.3 mg/kg) or chloroquine in drinking water (9250 mg/120 mL) may be used
• Grape or orange juice can be used to disguise the bitterness of chloroquine

Malaria-Carrying Parasites

• Includes Trypanosomes, Babesia spp., and other protozoan parasites of birds
• May be transmitted by ticks or other invertebrate hosts

Chicken Anemia Virus Infection

• Also known as Avian Anemia, Blue Anemia Virus Infection, Anemia Dermatitis Syndrome, and Hemorrhagic Anemia Syndrome
• Etiology, epidemiology, and pathogenesis involve the CAV virus, a 25 nm, non-enveloped, icosahedral virus with a single-stranded, circular DNA genome
• Proposed to belong to the Circoviridae family
• Described in most countries with a developed chicken industry
• Not known to infect other birds other than chickens
• Transmitted through vertical and horizontal routes

Dissecting Aneurysm/Aortic Rupture/Internal Hemorrhage

• Rupture of the ventral wall of the posterior aorta at the position of the testes or in the cardiac atrium
• Aortic lumen may contain an organized adherent thrombus at the site of rupture, with intimal thickening or a large fibrous plaque present
• Marked accumulation of lipids in thickened intima and fibrous plaque can be identified by stains
• Dx: by finding large clots of blood in the coelomic cavity (aortic rupture) or within the pericardial sac (auricular rupture) of rapidly growing male turkeys
• Differential Dx: hypertensive angiopathy, lesions include pulmonary edema and subscapular perirenal hemorrhage

Inclusion Body Hepatitis (IBH)

• Is an acute disease of young chickens associated with anemia and hemorrhagic disorders
• Also reported in quails with infectious bronchitis
• Cause: Adenovirus
• Etiology, transmission, and pathogenesis involve a birnavirus and a circovirus, which contribute to immunosuppression and the severity of the disease

Perirenal Hemorrhage Syndrome of Turkeys

• Dx: based on history, typical gross lesions, and absence of infectious agents
• Tx: no specific treatment, but factors that decrease growth rate and activity tend to decrease PHS

Round Heart Disease of Turkeys

• Spontaneous cardiomyopathy of young turkeys characterized by sudden death due to cardiac arrest
• Etiology is unknown, but may be due to altered membrane transport resulting in myocardial failure
• Most deaths occur during the brooding period, with mortality peaking at 2 weeks
• Many poults die suddenly, with some showing ruffled feathers, drooping wings, and a general unthrifty appearance
• Dx: based on history and gross findings at necropsy
• No tx is available, but good brooding practices may reduce mortality