Hemoparasites

Question 1

Hemotropic Mycoplasmas

gram-negative bacteria

Answer 1

• epicecullar parasites - associated w/ membrane surface
• very small cocci, rod, or ring-shaped structures
• found individually or in chains
• PCR testing rec. for definitive diagnosis if infxn suspected
• most domestics have at least 1 species that infects them
• when they cause anemia 🡒 expect hemolytic anemia (often extravascular)
• treated animals may become carriers 🡒 recurrence possible

• can fall of RBCs during transport in vitro
• can be confused for stain precipate or vice versa

Question 2

Mycoplasma haemofelis

formerly hemobartonella felis

Answer 2

• can cause disease in normal animals
• concurrect retroviral infection (FeLV/FIV) can 🡑 susceptibility
• infxn can result in severe hemolytic anemia
• cyclic parasitemia
• survivors often remain carriers

Transmission:
- presumptive vectors: fleas, ticks, mosquitoes
- blood (+ transfusions)
- vertical (queen 🡒 kittens)

Question 3

Theileriosis

protozoan

Answer 3

protozoal organism that affects ruminants + cervids

species in US are often non-pathogenic but can cause hemolytic anemia

multi-stage lifecycle
- piroplasms in RBCs
- schizonts in lymphocytes

Question 4

Morphologic overlap between several IC organisms:

Answer 4

Theileria spp. + cytauxzoon felis + babesia spp.

we use patient species +/- geographic location to develop plausible differential diagnosis lists

then use molecular testing to definitively identify organism

Question 5

Cytauxzoon felis

(protozoan)

Answer 5

feline pathogen of southern + south-central + midwest + mid-atlantic US

piroplasms in RBCs
- basophillic, round to signet-ring structures
- ~1-3 microns in diameter

bobcat (lynx rufus) is the wild reservoir
tick vectors

schizonts in tissue macrophages
- these parasitized macrophages are very large + affect blood flow + cell function in affected organs 🡒 accumulation is main cause of clinical signs

can cause severe disease + fatality
- marked depression + lethargy
- high fever
- marked icterus
- leukopenia + thrombocytopenia
- anemia

often fatal for cats that become symptomatic

Question 6

Babesiosis

protozoan

Answer 6

mainly seen in dogs + cattle

sporozoites penetrate + multiply in RBCs
- can rupture RBCs + subsequently invade other RBCs
- cause IV hemolytic anemia +/- thrombocytopenia
- do not infect other cell types

large (>3u) + small (<3u) Babesia spp.

Question 7

Anaplasmosis

rickettsia

Answer 7

Cattle - anasplasma marginale
- tick vectors, mechanical transmission
- 🡑 parasitemia occurs until anemia develops 🡒 hemolytic crisis
- fever, mild to severe anemia
- survivors become chronic carriers + serve as reservoirs

Must be differentiated from howell-jolly bodies:
- usually anaplasma organisms are not perfectly round + may be smaller than typical H-J bodies

Question 8

Hemoproteus + Hemogregarines

protozoa

Answer 8

Birds = hemoproteus v reptiles = hemogregarines

usually non to mild pathogenic

Question 9

Plasmodium

protozoa

Answer 9

birds + reptiles
clinical dz more common to certain bird species

Question 10

Leukocytozoon

protozoa

Answer 10

birds
pathogenicity low for most birds

Question 11

Microfilaria

Answer 11

dirofilaria immitis = dogs + cats
dirofilaria repens = dogs + cats in europe
anathoceilonema reconditum = dogs
setaria sp. = cattle + horses
- intestinal roundworm that has a microfilarial stage