Difference between revisions of "Feline Infectious Anaemia"

Revision as of 10:56, 15 March 2012

Previously known as: Haemobartonellosis

Caused by: Mycoplasma haemofelis , previously known as Haemobartonella felis

Introduction

Feline Infectious Anaemia, caused by Mycoplasma haemofelis (Mhf), is a regenerative anaemia of cats. The disease occurs worldwide and should be considered as a differential diagnosis for any cat presenting with anaemia.

Aetiology

Mhf is one of a group of organisms known as haemotropic mycoplasmas which infect several other domestic animal species. The causative organism was previously called Haemobartonella felis and thus the disease was known as haemobartonellosis. Polymerase chain reaction (PCR) assays allowing DNA analysis resulted in the reclassification of the organism in 2001. Two other haemotropic mycoplasmas (Candidatus M. haemominutum and Candidatus M. turicensis) have been identified in cats but appear to be less pathogenic¹.

The mode of transmission of Mhf is poorly understood.

Signalment

The major group at risk for Mhf infection are male cats who spend time outdoors. In many areas of the world an association has been shown between Mhf and retroviral infections¹.

Clinical signs

The peracute disease is associated with severe anaemia and immunosuppression, and can be rapidly fatal.

Fever, anaemia, depression, weakness and jaundice occur in the acute form. In the chronic form animals present with anaemia, lethargy and weight loss.

Cyclic fever may also occur during the transient period of parasitaemia.

Recovery can occur with a regenerative bone marrow response, however severe anaemia may occur in the presence of feline leukaemia virus (FeLV).

Diagnosis

The best diagnostic test is a PCR, which is very sensitive and enables differentiation of the different species.

The organism can also be diagnosed on blood smears. The organism can be intermittently seen microscopically on the surface of red blood cells on Giemsa-stained blood smears. The organism stains blue and can look like rings or rods.

Erythrophagocytosis may be evident and parasitised erythrocytes will become spherical.

The organism must be differentiated from Howell-Jolly bodies and other parasites. Due to the cyclic parasitaemia the organism causes, negative blood smears will not rule out the disease.

Additionally Immunofluorescence of blood smears can demonstrate the organism.

Haematology will show a decreased packed cell volume and a low red blood cell count. The anaemia is usually regenerative. FeLV infection is associated with macrocytosis.

Treatment

Infected cats should be treated with doxycycline for 3 weeks twice daily. Enrofloxacin is also a good treatment choice especially in refractory cases when combined with doxycycline.

A blood transfusion may also be required in cases of severe anaemia.

As blood sucking endoparasites, such as Fleas, are thought to spread disease the animal should also receive flea treatment.

Prednisolone is also advised to treat the immune mediated mechanisms and to prevent further erythrophagocytosis.

Prognosis

Varied prognosis depending on the severity of the anaemia at presentation. If not treated 1/3 of affected animals will die. Antibiotics do not clear the infection so many cats become carriers of the organism however relapses are uncommon.

Feline Infectious Anaemia Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Emergency and Critical Care Medicine Q&A 12
Literature Search Search for recent publications via CAB Abstract (CABI log in required)	Mycoplasma haemofelis publications Feline Infectious Anaemia publications
Full Text Articles Full text articles available from CAB Abstract (CABI log in required)	Diagnosis and management of Hemoplasma infections. Lappin, M. R.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 655-656, 23 ref. Bartonellosis and hemoplasmosis in dogs and cats: emerging issues. Lappin, M. R.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Volume 21, Orlando, Florida, USA, 2007, 2007, pp 629-631

References

Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)W.B. Saunders Company

Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+Previously known as: '''Haemobartonellosis'''
-{{Summary
-|cause = ''Mycoplasma haemofelis''
-|signalment = Male cats with outdoor access
-|associated = Feline retroviruses
-|differentials = Other causes of anaemia
-|diagnosis = PCR, blood smear examination
-|treatment = Doxycycline
-}}
-Also known as: '''''FIA — Haemoplasmosis — Hemoplasmosis'''''; previously known as: ''Haemobartonellosis''
-Caused by: '''''Mycoplasma haemofelis (Mhf)''''' (previously known as ''Haemobartonella felis''), '''''Candidatus M. haemominutum (Mhm) — Candidatus M. turicensis (Mtc)'''''
+Caused by: '''''Mycoplasma haemofelis''''' , previously known as '''''Haemobartonella felis'''''
 ==Introduction==
-Feline Infectious Anaemia is a [[Regenerative_and_Non-Regenerative_Anaemias|regenerative anaemia]] of cats caused by '''''Mycoplasma haemofelis''''' (Mhf). The disease occurs worldwide and should be considered as a differential diagnosis for any cat presenting with anaemia.
+Feline Infectious Anaemia, caused by '''''Mycoplasma haemofelis''''' (Mhf), is a regenerative anaemia of cats. The disease occurs worldwide and should be considered as a differential diagnosis for any cat presenting with anaemia.
 ==Aetiology==
-Mhf is one of a group of organisms known as haemotropic [[Mycoplasmas|mycoplasmas]] which infect many mammalian species. The causative organism was previously called ''Haemobartonella felis'' and thus the disease was known as haemobartonellosis. [[Polymerase_Chain_Reaction|Polymerase chain reaction]] (PCR) assays allowing DNA analysis resulted in the reclassification of the organism as a mycoplasma in 2001<ref name="Niemark">Niemark H, Johansson KE, Rikihisa Y, et al (2001) Proposal to transfer some members of the genera ''Haemobartonella'' and ''Eperythrozoon'' to the genus ''Mycoplasma'' with descriptions of Candidatus ''Mycoplasma haemofelis'', Candidatus ''Mycoplasma haemomuris'', Candidatus ''Mycoplasma haemosuis'' and Candidatus ''Mycoplasma wenyonii'' '''Int J Sys Evol Microbiol 51(3) pp891-9</ref>. Two other haemotropic mycoplasmas (''Candidatus M. haemominutum'' (Mhm) and ''Candidatus M. turicensis'' (Mtc)) have also been identified in cats but appear to be less pathogenic<ref name="Sykes">Sykes, JE (2010) Feline Hemotropic Mycoplasmas '''Vet Clinics of North America: Small Animal Practice''' pp. 1157-1170</ref>.
+Mhf is one of a group of organisms known as haemotropic mycoplasmas which infect several other domestic animal species. The causative organism was previously called Haemobartonella felis and thus the disease was known as haemobartonellosis. Polymerase chain reaction (PCR) assays allowing DNA analysis resulted in the reclassification of the organism in 2001. Two other haemotropic mycoplasmas (''Candidatus M. haemominutum'' and ''Candidatus M. turicensis'') have been identified in cats but appear to be less pathogenic<sup>1</sup>.
+The mode of transmission of Mhf is poorly understood.
-Mhf can vary in shape from cocci to rods and is sometimes present as chains of organisms on the surface of [[Erythrocyte|erythrocytes]].
-[[File:M haemofelis2.jpg|thumb|''Mycoplasma haemofelis'' on the surface of an erythrocyte]]
-==Transmission==
-The mode of transmission of Mhf is poorly understood. Several possibilities have been proposed but none have been able to be reliably demonstrated. These include:
-* Biting and fighting activities. Infection by this route has not been able to be demonstrated experimentally.
-*[[Fleas|Fleas]]. The fact that Mhf infection can be prevalent in areas where fleas are uncommon makes this less likely.<ref name="Jensen"> Jensen WA, Lappin MR, Kamkar S et al (2001) Use of a polymerase chain reaction assay to detect and differentiate two strains of ''Haemobartonella felis'' in naturally infected cats. '''Am J Vet Res''' 62(4):604-8 </ref>
-*[[Arthropods|Arthropods]]. Geographic variation in rates of Mhf infection does exist and could be due to transmission by an arthropod. <ref name="Willi">Willi B, Boretti FS, Baumgartner C et al (2006) Prevalence, risk factor analysis and follow-up of infections caused by three feline haemoplasma species in Switzerland. '''J Clin Microbiol''' 44(3):961-9</ref>
-As transmission has been shown to occur through blood transfusion due to the ability of the organism to survive in stored blood products for up to 7 days <ref name="Gary">Gary AT, Richmond HL, Tasker S etal (2006) Survival of ''Mycoplsma haemofelis'' and ''Candidatus'' Mycolplasma haemominitum in blood of cats used for transfusions '''J Feline Med Surg''' 8(5):321-6</ref>, it is recommended that blood donors be screened.<ref name="Wardrop">Wardrop J, Reine N, Birkenheuer A et al (2005) Canine and feline blood donor screening for infectious disease '''J Vet Intern Med''' 19(1) pp.135-42.</ref>
 ==Signalment==
-The major group at risk for Mhf infection are young male cats who spend time outdoors. In many areas of the world an association has been shown between Mhf and [[Retroviridae|retroviral infections]]<ref name="Sykes" />. It has been demonstrated that cats infected with Mhf and [[Feline_Leukaemia_Virus|feline leukaemia virus (FeLV)]] are likely to develop more severe anaemia that cats infected only with Mhf <ref name="Wardrop"></ref>.
+The major group at risk for Mhf infection are male cats who spend time outdoors. In many areas of the world an association has been shown between Mhf and retroviral infections<sup>1</sup>.
-==Pathogenesis==
-The pathogenesis of Mhf is not fully understood. It is thought that the presence of the parasite on the surface of the erythrocytes may induce [[Immunoglobulins_-_Overview|antibody production]]<ref name="Hagiwara"></ref>, resulting in [[Regenerative_and_Non-Regenerative_Anaemias#Haemolysis|haemolysis]] which is primarily extravascular. The haemolysis may be due to direct damage of erythrocytes by the organism or as a result of the antibodies produced by the infected animal <ref name="Wardrop"></ref>.
-Cats can produce an immune response which results in the disappearance of organisms from the blood. Production of uninfected erythrocytes can then result in an increase in [[haematocrit]].
-It is thought that recovered cats can become subclinical carriers, with the potential for the disease to recrudesce if the animal is in a stressed state eg pregnancy, illness.<ref name = "Harvey">Harvey JW and Gaskin JM (1978)Feline haemobartonellosis;attempts to induce relapses of clinical disease in chronically infected cats.'''J Am Anim Hosp Assoc'''14:453</ref>
-[[File:M haemofelis.jpg|thumb|''Mycoplasma haemofelis'' on the surface of blood cells]]
 ==Clinical signs==
+The peracute disease is associated with severe anaemia and immunosuppression, and can be rapidly fatal.
-Infected cats most commonly present for lethargy and decreased appetite. Physical examination findings are non-specific and can include signs of anaemia, such as mucous membrane pallor, tachypnoea and tachycardia, pyrexia, and occasionally splenomegaly and [[Icterus|jaundice]]. Pyrexia is frequently intermittent and spikes when parasite numbers are highest <ref name="Wardrop"></ref>.  The anaemia can be severe and rapidly fatal in some cases.
+Fever, anaemia, depression, weakness and [[Icterus|jaundice]] occur in the acute form. In the chronic form animals present with [[Regenerative and Non-Regenerative Anaemias|anaemia]], lethargy and weight loss.
-==Differential diagnosis==
-There are multiple causes of both [[Regenerative and Non-Regenerative Anaemias|regenerative and non-regenerative anaemia]] in cats which must be considered as differential diagnoses.
-For cats showing signs of regeneration, causes of blood loss or haemolysis must be considered:
-*[[Immune_Mediated_Haemolytic_Anaemia|primary immune-mediated haemolytic anaemia]]
-*Heinz body haemolytic anaemia (onions, garlic, [[propofol]])
-*other infectious causes such as [[Babesia|''Babesia felis'']] and [[Cytauxzoon#Cytauxzoon_felis|''Cytauxzoon felis'']]
-*[[Neoplasia_-_Pathology|neoplasia]]
+Cyclic fever may also occur during the transient period of parasitaemia.
-Major differential diagnoses for cats with non-regenerative anaemia include:
+Recovery can occur with a regenerative bone marrow response, however severe anaemia may occur in the presence of [[Feline Leukaemia Virus|feline leukaemia virus]] (FeLV).
-*neoplasia
-*chronic inflammatory conditions
-*underlying conditions such as [[Diabetes_Mellitus|diabetes mellitus]] and [[Chronic_Renal_Failure|renal disease]]
-*[[FIV|Feline Immunodeficiency Virus(FIV)]] and [[FeLV]] infections
-*[[Regenerative_and_Non-Regenerative_Anaemias#Failure_of_the_bone_marrow_stem_cells_to_produce_erythroid_cells|bone marrow diseases]]
 ==Diagnosis==
+The best diagnostic test is a PCR, which is very sensitive and enables differentiation of the different species.
-The most commmon findings from complete blood counts from cats with Mhf infections are a '''macrocytic, hypochromic regenerative anaemia'''. [[Reticulocyte|Reticulocytes]] and [[Howell-Jolly Bodies|Howell-Jolly bodies]] may be identified on cytologic examination.
+The organism can also be diagnosed on blood smears.
+The organism can be intermittently seen microscopically on the surface of red blood cells on Giemsa-stained blood smears. The organism stains blue and can look like rings or rods.
+Erythrophagocytosis may be evident and parasitised erythrocytes will become spherical.
-Mhf infection can be definitively diagnosed by identification of organisms on a blood smear, appearing as cocci or rods and sometimes forming short chains of organisms. However, examination of a single blood smear is less than 50% sensitive <ref name="Hagiwara"> Hagiwara, MK (2009) Anemia in Cats: Is It Mycoplasma? '''Proceedings of the 34th World Small Animal Veterinary Congress'''</ref> as the animal's immune response causes organisms to disappear from the blood stream for several days, often to reappear a few days later. One study found that smears should be examined every four days over a minimum of three four day cycles<ref name="Ettinger>Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2) W.B. Saunders Company</ref>, making it possible to have eight days between presentation and diagnosis. It also has the potential for misidentification of organisms.
+The organism must be differentiated from [[Regenerative and Non-Regenerative Anaemias|Howell-Jolly bodies]] and other parasites. Due to the cyclic parasitaemia the organism causes, negative blood smears will not rule out the disease.
+Additionally [[Immunofluorescence]] of blood smears can demonstrate the organism.
-The gold standard for diagnosis of Mhf infection is polymerase chain reaction (PCR), which detects the 16S RNA gene. The test is widely available through veterinary diagnostic laboratories. There are two types of PCR tests; conventional PCR which uses the presence or absence of bands on a gel to assess infection, and real-time PCR assays which uses fluoresence to mark a segment of DNA unique to the organism, making it highly sensitive and species-specific and thus the test of choice <ref name="Sykes"></ref>. Treatment with antimicrobials may result in false negatives on PCR so collecting before beginning therapy is preferable.
+Haematology will show a decreased packed cell volume and a low red blood cell count. The anaemia is usually regenerative. FeLV infection is associated with macrocytosis.
 ==Treatment==
-The treatment of choice for Mhf infection is [[Tetracyclines|doxycycline]] for at least two weeks. Only cats who are anaemic and have clinical signs and laboratory results consistent with haemoplasmosis should be treated as the drug does not reliably eliminate the organism<ref name="Sykes"></ref>. For this reason a PCR-positive cat may not become negative despite treatment and therapy cannot be used to ensure blood donor cats are free from infection.
+Infected cats should be treated with [[Tetracyclines|doxycycline]] for 3 weeks twice daily. [[Fluoroquinolones|Enrofloxacin]] is also a good treatment choice especially in refractory cases when combined with doxycycline.
-[[Fluoroquinolones|Enrofloxacin]] is also an effective treatment <ref name="Tasker">Tasker, S, Helps CR, Day MJ et al.(2004) Use of a Taqman PCR to determine the response to ''Mycoplasma haemofelis'' infection to antibiotic treatment. '''JMicrobiol Methods''' 56(1):63-71</ref> but is a second choice due to the risk of acute retinal damage in cats.
 A [[:Category:Transfusion Medicine|blood transfusion]] may also be required in cases of severe anaemia.
-Antimicrobial therapy and blood transfusions should be initiated before PCR results are known, as this may take several days. In cats testing negative for Mhf and failing to respond to therapy, alternative diagnoses should be considered.
+As blood sucking endoparasites, such as [[:Category:Fleas|Fleas]], are thought to spread disease the animal should also receive flea treatment.
-The use of [[Steroids|glucocorticoids]] to suppress immune-mediated damage to erythrocytes has been suggested. However, as this treatment may cause reactivation of a latent infection it is recommended that they only be used in cats not responding to doxycycline and/or for whom there is no definitive diagnosis.
+Prednisolone is also advised to treat the immune mediated mechanisms and to prevent further erythrophagocytosis.
 ==Prognosis==
-Prognosis for infected cats is related to the severity of the anaemia at presentation. If an animal survives the initial anaemia prognosis for clinical recovery is good. However, antibiotics do not clear the infection so many cats become carriers of the organism. Affected animals may also have intercurrent disease, such as retroviral infections, which will also affect the prognosis.
+Varied prognosis depending on the severity of the anaemia at presentation. If not treated 1/3 of affected animals will die. Antibiotics do not clear the infection so many cats become carriers of the organism however relapses are uncommon.
 {{Learning
@@ Line 99: / Line 57: @@
 [http://www.cabi.org/cabdirect/FullTextPDF/2007/20073119573.pdf ''' Bartonellosis and hemoplasmosis in dogs and cats: emerging issues.''' Lappin, M. R.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Volume 21, Orlando, Florida, USA, 2007, 2007, pp 629-631]
-|Vetstream = [https://www.vetstream.com/felis/Content/Disease/dis60170 Feline infectious anemia]
 }}
 ==References==
-<references/>
+Ettinger, S.J, Feldman, E.C. (2005) '''Textbook of Veterinary Internal Medicine''' (6th edition, volume 2)''W.B. Saunders Company''
-==Extra references==
 Merck & Co (2008) '''The Merck Veterinary Manual''' (Eighth Edition) ''Merial''
-{{Rebekah Brown
+{{review}}
-|date = July 3, 2012 }}
+[[Category:Anaemia]]
-{{OpenPages}}
-[[Category:Anaemia|5]]
 [[Category:Lymphoreticular and Haematopoietic Diseases - Cat]][[Category:Cat Bacteria]]
 [[Category:Expert_Review - Small Animal]]