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Name: Haemobartonellosis
Short Description
Haemobartonellosis, Haemobartonella infection.
Affected Animals:
Essentially all cats have the potential to be
infected with Haemobartonella felis.Cats infected with feline
leukemia virus appear to be at higher risk for infection and are
likely to have more severe signs of illness.
Overview: Haemobartonellosis, or feline infectious anemia,
is a parasitic disease caused by Haemobartonella felis. The disease
process begins when H. felis organisms attach themselves to the red
blood cells of infected cats. H. felis may be spread by a number of
routes, although fleabites are thought to be the major mode of
transmission. While some infected cats have no symptoms, others may
develop severe anemia and illness. The infection is diagnosed
microscopically when the organisms are found on the surface of red
blood cells in a blood smear. However, since the organisms may not
always be present, treatment is often initiated in an anemic cat if
there is no other explanation for the anemia. Specific treatment for
feline infectious anemia includes tetracycline antibiotics and
prednisone. Patients may require supportive care, including blood
transfusion. Although treatment does not eliminate the infection
completely, cats that survive are thought to have a good long-term
outlook.
Clinical Signs:The severity of clinical signs
associated with Haemobartonella infection usually corresponds to the
degree of anemia present, or the speed with which it develops. Cats
with mild anemia may show no overt signs of illness. In severely
anemic cats, or in cats that rapidly become anemic, signs can
include depression, lethargy, inappetance, pallor, jaundice and
splenomegaly. The temperature may be elevated, but in cats with
life-threatening anemia, the body temperature is often subnormal.
Symptoms: Cats with mild, Haemobartonella-induced anemia
may not show any symptoms of disease. In cats with severe anemia, or
in cases where the anemia develops quickly, symptoms include
weakness, depression, reduced appetite, decreased activity, and pale
or jaundiced mucous membranes. Cats that are severely ill may be in
shock, with below normal body temperature.
Description: Feline infectious anemia is caused by the
organism Haemobartonella felis. This organism may be spread by
fleabites, cat bites, blood transfusion, and by mothers to their
kittens. Some cats infected with Haemobartonella have no symptoms,
while others can develop life-threatening anemia. Cats that are also
infected with feline leukemia virus are expected to have more severe
signs of illness. Symptoms can include fever, depression, and loss
of appetite. Signs of anemia may include lethargy, weakness, pale or
jaundiced mucous membranes, and increased respiratory rate and
effort. Severely affected cats may appear to be prostrate and
depressed, or in shock. They can die suddenly with no apparent
warning.
The anemia arises as infected red blood cells are attacked and
destroyed by the immune system. The spleen is one of the major sites
of red blood cell destruction. If the hemolytic process is severe,
pigments from red blood cell breakdown may accumulate in the blood
stream, resulting in jaundice.
Haemobartonella should be considered as a possibility in any anemic
cat or any cat with evidence of hemolysis. The diagnosis is based on
microscopic identification of H. felis on a blood smear. Since the
appearance of H. felis on red blood cells is cyclical, the organisms
may not be present all the time. In many cases, treatment is begun
even if the diagnosis is only suspected and not confirmed.
Treatment of haemobartonellosis includes tetracycline antibiotics
and prednisone. Blood transfusions may be required in patients with
severe anemia. In cats that recover, a chronic carrier state
develops. These chronic infections may persist for the life of the
cat. Without treatment, as many as one out of every three cats with
haemobartonellosis will die from the disease. Although they may be
carriers of the organism, successfully treated cats have a good
long-term outlook. Control of flea and tick infestations may help
prevent re-infection with Haemobartonella.
Diagnosis:
The confirmation of H. felis infection rests on
the microscopic identification of the organisms on the surface of
red blood cells on a blood smear. It is easy to confuse the
organisms with other red blood cell changes. The presence of the
organisms in an otherwise normal cat may be an incidental finding.
The absence of the organism in an anemic cat does not rule out the
disease, since their appearance in circulation appears to be
cyclical. Furthermore, the parasites clear rapidly upon treatment
with antibiotics, making detection difficult. Special laboratory
stains may be helpful in identifying the organism microscopically. A
sophisticated test called polymerase chain reaction, or PCR, may
also help establish the diagnosis. This test looks for genetic
material unique to H. felis.
Prognosis: With successful treatment, the outcome for cats
with feline infectious anemia appears to be good. Successful
treatment does not completely eliminate the organism, and previously
affected cats may serve as carriers. Some authorities have suggested
that carrier cats can relapse if their body defenses are weakened.
However, no clinical evidence exists to support this concept.
Transmission or Cause:The cause of Haemobartonellosis is an organism
called Haemobartonella felis, a parasite that attaches to the
surface of red blood cells in infected cats. Fleabites may be the
primary means of spread. The organism can be passed from mother cats
to their kittens, but it is not known whether this spread occurs
prior to birth, during birth, or through nursing. The organisms may
be passed via blood transfusion. Some authors suggest that cat bites
may also transmit the organisms.
Treatment: Treatment for haemobartonellosis includes blood
transfusion, antibiotics, and prednisone. Blood transfusions are
used to temporarily stabilize severely anemic cats, replenishing the
number of red blood cells. The need for transfusion is based on the
cat's overall condition.
Tetracycline antibiotics are employed to eradicate as many H. felis
organisms as possible. Doxycycline is probably the most frequently
prescribed antibiotic in this class because it usually causes fewer
side effects than other tetracyclines. Suppression of appetite,
nausea or vomiting are common signs of adverse drug reaction. The
drugs do not completely eliminate the infection, but they appear to
lessen the severity of the disease.
Prednisone is frequently prescribed in cases of feline infectious
anemia. This corticosteroid medication is used to help block immune
system-mediated red blood cell destruction.
Haemobartonellosis remains one of the few specifically treatable
causes of severe anemia in cats. In many circumstances, treatment is
started when the disease is suspected, even if the organisms are not
identified.
Prevention: Careful attention to elimination of fleas and the
prevention of flea infestation should reduce the possibility of
flea-borne spread of H.felis. Screening of donor cats to be sure
they do not harbor the Haemobartonella organism may prevent spread
via blood transfusion.
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