ETIOLOGY AND TRANSMISSION OF FELINE LEISHMANIOSIS

Feline Leishmania infections have been observed all over the world and are caused by endemic species also infecting humans and other animals in those areas.

Leishmania infantum is transmitted to cats by sand flies, as these have been shown to feed on cats and to be infected after feeding on naturally infected cats. To date, non-vectorial transmission has not been described in cats but blood transfusion may be a source of infection of cats similar to humans and dogs.

 
GEOGRAPHIC DISTRIBUTION AND RISK FACTORS

Most information regarding feline L. infantum infection has come from the cases reported within the Mediterranean basin.

The prevalence rate of L. infantum infection in cats, as evaluated in many studies, is not negligible; however, it is commonly lower than the prevalence of canine infection.

Prevalence of L. infantum in Mediterranean countries (diverse serological or blood PCR techniques) according to studies performed in cats (1982 – 2017).

 
  SEROLOGY (1982-2017) BLOOD-BASED PCR (2000-2017)
Prevalence Studies (n) Countries Studies (n) Countries
< 5% 16 Albania-Cyprus-Egypt-Greece-Italy-Portugal-Spain 9 Cyprus-Italy-Portugal-Spain-Turkey
5-25% 11 Egypt-France-Greece-Israel-Italy-Portugal-Spain-Turkey 7 Greece-Italy-Portugal-Spain
>25% 7 Italy-Spain 5 Italy-Portugal-Spain
 

Clinical feline leishmaniosis (FeL) remains rare, even in areas where the disease is common in dogs. It is postulated that cats are therefore more resistant than dogs to L. infantum infection, but it cannot be excluded that the disease is underdiagnosed because it is unknown to most practitioners and masked by concurrent diseases, and feline medicine is still underdeveloped in many areas as compared to canine medicine.

Considering that cats may be a source of infection for sand flies and that cats may suffer from chronic infection, LeishVet postulates that infected cats may represent an additional domestic reservoir for L. infantum.

Approximately 100 clinical cases were reported in Europe during the last 25 years (Italy, Spain, France, Portugal) with some cases diagnosed (Switzerland) in cats imported from endemic regions.

Host factors predisposing to susceptibility may exist, as roughly half of the reported clinical cases have been observed in cats that could have had an impaired immune system secondary to feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV) infections, immune-suppressive therapies or debilitating concomitant diseases.

Geographic distribution of feline Leishmania spp. infection is summarized below.

Leishmania spp. detected in cats and countries where infection and/or disease cases were reported (1982-2017).

 
Leishmania species Old World Countries New World Countries
L. infantum Cyprus – France – Greece – Iran – Israel – Italy – Portugal – Spain – Switzerland* – Turkey Brazil – Mexico
L. braziliensis Brazil – France (French Guiana) – Mexico
L. mexicana Mexico – USA (Texas)
L. venezuelensis Venezuela
L. amazonensis Brazil
L. tropica Turkey
L. major Turkey

*Cats rehomed from Spain