Rickettsia, Mycoplasma, Anaplasma Flashcards
Anaplasma marginale (host)
cattle
Anaplasma marginale (morphology)
spherical granules seen in RBCs (1-7/cell) usually located near the periphery of the cell with a slight halo around them; uniform in size
Anaplasma marginale(transmission)
by mechanical
transfer of blood by vectors – stable flies, ticks, mosquitoes, needles, etc.
Anaplasma marginale (clinical signs)
worse in cattle 2-3 years of age or older; causes hemolytic anemia; may be peracute (1day); acute (several days), subacute (2-3 weeks), or chronic (longer). Severe anemia, weakness, fever (104-107°F), depression, anorexia, dehydration, constipation, icterus
Anaplasma marginale (treatment)
Treatment: tetracyclines, blood transfusions, supportive care
*All recovered animals are permanent carriers
Prevention: Vaccine – has problems
Equine Granulocytic Ehrlichiosis
Now known to be caused by Anaplasma phagocytophilum
Syndrome affecting horses mainly in northern California, but has been seen in other states
A different strain of this organism causes human granulocytic ehrlichiosis; this is not thought zoonotic
Tick borne
Signs vary from mild to severe
Treatment is oxytetracycline
Ehrlichiosis (host and morphology )
Host: canids, humans, others
Morphology: Mulberry or morula form readily visible in cytoplasm of infected WBCs (Wright’s stain
Ehrlichiosis (clinical importance)
c. Clinical disease: causes pancytopenia (thrombocytopenia, leukopenia, anemia)- fever, depression, ocular and nasal discharges, occasional lameness, splenomegaly, *bleeding
Other possible Ehrlichia species are described, including one affecting platelets – life cycles are not all defined at present
Tick borne
Tetracyclines are tx of choice
Potomac Horse Fever
Neorickettsia risticii – causes Potomac Horse Fever, first described in 1979. Was originally thought to be an Ehrlichia species. The rickettsial organism is transmitted from snails to mayflies and caddis flies, which bring the organism to horse food and water sources. There appear to be several strains, and not all is known about potential sources of infection. It causes generalized disease with colitis and diarrhea as a prominent clinical sign.
Diagnosis is by PCR
Vaccines are available but of questionable efficacy
Tetracyclines remain the treatment of choice.
Supportive care is recommended.
Hemotropic Mycoplasmas
Morphology: Ring-like structure on the RBCs most often – may have some variations; they are pleomorphic gram-negative bacteria lacking a cell wall, and have not been cultured outside their hosts
Mycoplasma suis – swine – anemia
Mycoplasma wenyoni – cattle – only very mild anemia; usually not noticed
Mycoplasma ovis – sheep and goats – not clinically very important
These were previously known as Eperythrozoon
Mycoplasma sp. (previously known as Haemobartonella)
Mycoplasma haemofelis produces anemia from mild to severe – depends on number of organisms present and susceptibility of host. Often associated with Feline Leukemia Virus infection. Disease state is called Feline Infectious Anemia. Typical infection causes a PCV of <18%; regenerative anemia.
Treatment is tetracyclines or enrofloxacin; remain carriers after treatment, and disease may reemerge with immunocompromised.
One human case has suggested zoonotic potential in immunocompromised individuals.
Mycoplasma haemocanis
clinical anemia doesn’t frequently occur in intact animals; many are probably carriers; clinical infections usually associated with splenectomized dogs. Treatment is tetracyclines, but treated animals remain carriers.
Bartonella henselae; B. quintana; other sp.
Cat scratch disease transmitted by fleas, disease in canids, humans, rodents, etc.
Has been linked to with lymphadenopathy (sometimes resembles lymphoma), endocarditis, uveitis, neurologic disease in humans
May be the “hidden epidemic”
Testing by special culture, PCR
Treatment is tetracyclines plus another drug (rifampin, etc.)
Rocky Mountain Spotted Fever
Rickettsia rickettsii
Tick borne
Fever, rash, neurologic, pulmonary, and kidney signs
Up to 30% or higher mortality if untreated before neurologic signs begin
