Changes

Previously known as: '''Haemobartonellosis'''

Previously known as: ''Haemobartonellosis''

Caused by: '''''Mycoplasma haemofelis''''' , previously known as '''''Haemobartonella felis'''''

Caused by: '''''Mycoplasma haemofelis''''', previously known as ''Haemobartonella felis''

==Introduction==

==Introduction==

==Aetiology==

==Aetiology==

Mhf is one of a group of organisms known as haemotropic 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 (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 many mammalian 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 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 can vary in shape from cocci to rods and are sometimes present as chains of organisms on the cell surface.

Mhf can vary in shape from cocci to rods and are sometimes present as chains of organisms on the cell surface.

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:

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:

==Pathogenesis==

==Pathogenesis==

The pathogenesis of Mhf is not fully understood. It is thought that the presence of the parasite on the surface of the red blood cells may induce antibody production⁴. The anaemia, which is primarily extravascular, 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>.

The pathogenesis of Mhf is not fully understood. It is thought that the presence of the parasite on the surface of the red blood cells may induce antibody production<ref name="Hagiwara"></ref>. The anaemia, which is primarily extravascular, 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>.

==Clinical signs==

==Clinical signs==

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 splenomagaly and [[Icterus|jaundice]]. Pyrexia is frequently intermittent and spikes when parasite numbers are highest ³.  The anaemia can be severe and rapidly fatal in some cases.  

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 splenomagaly 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.  

==Differential diagnosis==

==Differential diagnosis==

*primary immune-mediated haemolytic anaemia

*primary immune-mediated haemolytic anaemia

*Heinz body haemolytic anaemia (onions, garlic,propofol)

*Heinz body haemolytic anaemia (onions, garlic,propofol)

*other infectious causes such as "Babesia felis" and "Cytauxzoon felis"

*other infectious causes such as ''Babesia felis'' and ''Cytauxzoon felis''

*neoplasia

*neoplasia

Mhf infection can be definitvely 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 cycles⁵, making it possible to have eight days between presentation and diagnosis - clearly not ideal. It also has the potential for misidentification of organisms.  

Mhf infection can be definitvely 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 - clearly not ideal. It also has the potential for misidentification of organisms.