Avian malaria (Hemoproteus, Leucocytozoon, Plasmodium).

Question 1

Describe the general life cycle of Avian Malaria:

Answer 1

In IH (bird):
1) Exo-erythrocytic stage: Mosquito injects sporozoites into the blood. They are then engulfed by macrophages OR they enter liver cells where they multiply to meronts/schizonts (schizogony/merogony). The schizont/meront ruptures and merozoites are released, which invades red blood cells in the liver.
2) Erythrocytic stage: Inside red blood cells, merozoites forms ‘‘ring-formed’’ trophozoites. Trophozoites divides, and produces schizonts/meronts. Merozoites are released into the bloodstream, causing MALARIAL PAROXYSM. The merozoites invades other red blood cells and repeats schizogony, but can also develop into gametocytes.

In FH (mosquito):
3) Gametocytes are ingested by the mosquito. Micro- and macrogametes fuse to become a motile zygote (gametogony) – ookinete – oocyst (sporogony) that ruptures and releases sporozoites. They move to the proboscis of the mosquito.

Question 2

Plasmodium species of birds

Answer 2

P. cathemerium, P. gallinaceum - Culex
P. relictum - Culex
P. juxtanucleare, P. circumflexum, P. elongatum
P. rouxi, P. lophurae, P. durae, P. polare, P. praecox, P. matulinum

Question 3

final host & vector in Plasmodium species of birds

Answer 3

Aedes, Culex, Anopheles - Mosquitos

Question 4

IH of Plasmodium species of birds

Answer 4

Birds

Question 5

location of Plasmodium species of birds

Answer 5

Blood and mononuclear phagocyte system

Question 6

pathogenesis of Plasmodium species of birds

Answer 6

Intermittent fever, splenomegaly, secondary anaemia.
Synchronization of meront development cause malaria fever attacks.

Question 7

Hemoproteus species

Answer 7

H. antigonis
H. columbae
H. meleagridis
H. canachites
H. laphortyx
H. nettionis
H. sacharovi

Question 8

final host and vector of Hemoproteus

Answer 8

Biting midges:

• Culicoides - avian ked
• Horse fly (Chrysops)

Question 9

IH of Hemoproteus

Answer 9

Birds, reptiles, amphibians

Question 10

location of Hemoproteus

Answer 10

Blood and mononuclear phagocyte system

Question 11

pathogenesis of Hemoproteus

Answer 11

• Subclinical infections and acute form in pigeon
• Enlarged stomach
• Hypertrophy of spleen, liver and kidney
• May have chocolate brown colour due to accumulated hemozoin
• Infected birds may have movement pain
• Fluffy feathers
• Exhaustion, weakness, death
• Anaemia (merozoites destroy nucleus of RBCs)
• Large megaloschizons may be present in skeletal muscle
• Average flock mortality may be above 20%
• Intermittent fever, splenomegaly, secondary anemia

Question 12

CS of Hemoproteus

Answer 12

Exhaustion, weakness, death, movement pain and anaemia, erythrocyte decay

Question 13

DX of haemoproteus

Answer 13

PCR, ELISA, blood stain under microscopy

Question 14

TX of haemoproteus

Answer 14

• Chloroquine
• Elimination of vector populations by insecticides and active efficient ventilation

Question 15

Leukocytozoon species

Answer 15

• L. simondi - ducks, geese
• L. smithi - turkey
• L. caulleryi - chicken
• L. sabrazesi - chicken
• L. andrewsi
• L. bonasae
• L. mansoni
• L. naevi - fowl

Question 16

final host & vector of Leukocytozoon

Answer 16

Black flies (Simulium spp.)

Question 17

IH of Leukocytozoon

Answer 17

Birds

Question 18

location of Leukocytozoon

Answer 18

Capillary endothelial cells, RES organs (liver, spleen), leukocytes, erythrocytes

Question 19

pathogenesis of Leukocytozoon

Answer 19

• 5 days after infection: many schizonts in hepatocytes, and the cell ruptures.
• 7 days after infection: megaloschizonts in spleen, lymphatics and other tissues - accumulation of gametocytes in the liver.
• 12 days after infection: haemorrhagic scars after megaloschizontal rupture.

Question 20

CS of Leukocytozoon

Answer 20

• Most birds are asymptomatic;
• Can show anorexia, emaciation, anaemia, weakness, depression, inability to fly, difficulty breathing, difficulty movement, young birds die within 24 hours.
• Increased sensibility to bacterial infection.
• Granulomatous lesions visible in the lungs, heart, brain, and peripheral nerves.
• After overcoming disease - immunity - adult birds are reservoirs of parasites.

Question 21

Dx of Leukocytozoon

Answer 21

• Microscopic examination of stained blood smears - finding gametocytes
• Histopathological examination of the liver, spleen and brain with finding megaschizonts
• Necropsy - enlargement of liver and spleen

Question 22

Tx of Leukocytozoon

Answer 22

Therapy is usually not effective

Question 23

Control of Leukocytozoon

Answer 23

Vector must be disposed of.
We can serve in feed:
- Pyrimethamine
- Sulfadimethoxin
- Clopidol
.

• Vector control: Quinacrin or Trimethoprim
• Oral anti-Leucocytozoonous vaccine can be used when parasitemia is reduced but infection is not obvious