Babesia Flashcards
What is the life cycle of babesia
Babesia organisms replicate in erythrocytes, where they produce merozoites. These structures appear as inclusions attached to each other at their ends, thereby forming tetrads.
These so-called Maltese cross formations are pathognomonic of Babesia species. Ticks are infected by ingesting merozoites during feeding, and replication of the parasite within their salivary cells results in sporozoite formation. When infected ticks feed, the sporozoites are regurgitated and fed back into the bloodstream of the host.
What are the clinical signs of babesia?
Mostly secondary to haemolytic anaemia that results from the infection of erythrocytes by the piroplasms
Weakness, lethargy, icterus, fever
Can vary from very mild to organ failure and death
Pigmenturia, organomegaly possible
What are some of the possible complications of babesia
Complications of babesiosis include acute or chronic nephropathy, glomerulonephritis, coagulation disorders (disseminated intravascular coagulation), jaundice from liver disease, immune-mediated hemolysis or thrombocytopenia, hemoconcentration, shock, metabolic and/or respiratory alkalosis, and/or acidosis, gastrointestinal disorders (vomiting or diarrhea), pancreatitis, mascites, ocular lesions (uveitis or blindness), myalgia, rhabdomyolysis and respiratory problems (edema or acute respiratory distress)
What are the typical haematology findings?
haemolytic anaemia, which is usually regenerative,
macrocytic and hypochromic. Haemolysis can
be caused by both extravascular and intravascular erythrolysis.
Anaemia is most pronounced approximately 3 weeks after an experimental infection.
Blood smears can show increased polychromatophils, HowellJolly bodies, nucleated erythrocytes and
anisocytosis. Erythrophagocytosis by monocytes is also observed, and intra-erythrocytic parasites can sometimes be detected.
Secondary, immune-mediated haemolytic anaemia with anti-erythrocyte antibodies can occasionally be seen, leading to a positive Coombs’ test and autoagglutination
Rare to see WBC changes
See thrombocytopaenia in dogs not cats
What are typical biochemical changes?
(ALT) activity is elevated in most cases, whereas alkaline phosphatase (ALP) activity is generally within the reference range.
Total bilirubin concentration is commonly increased,
most likely as a result of haemolysis, but secondary hepatocellular injury can be a contributing factor
Polyclonal gammopathy has been observed in cats with
hypergammaglobulinaemia, leading also to increased total protein concentrations
Does immunity develop?
The host generates a specific immune response against most Babesia species, but this does not eliminate the parasite. Cats that recover from the clinical signs usually remain chronic carriers
How do you diagnose babesia?
Can be seen on blood smears, easiest with romanowski stain - although sometimes can’t be seen
Smears are best taken from end capillaries - e.g. ear or nail. Seen as a ‘first step’ for dx
PCR in cats best option
Serology used in dogs, not available in cats
What negatively affects prognosis in cats
Concurrent infection with M hemofelis, FeLV or FIV
How do you treat it?
Cats - the drug of choice is primaquine phosphate, an antimalarial compound
Dogs - imidocarb for large species, combination of atovaquone and azithromycin for small
What are the main species that infect dogs?
either large (e.g. Babesia canis) or small forms (e.g. Babesia gibsoni)
What are the vectors and the geographical distributions of Babesia spp. causing disease in dogs in Europe?
For B. canis, the relevant vector is the tick Dermacentor reticulatus. This tick species has a relatively wide range across Europe, preferring cool and wet climates. While particularly abundant in large areas of central Europe, it can be found even in isolated pockets from Portugal to Poland.
Are there other modes of transmission aside from tick-borne for these infections in dogs?
Blood transfusion
Fighting
Possibly verticle
Why is the amplification of DNA by PCR useful in the
diagnosis of babesiosis? What biological samples should be chosen to perform a molecular diagnosis of Babesia spp. infections?
PCR detection is more sensitive than a direct blood smear examination.
The detection of DNA for a specific pathogen in a clinical setting can be considered evidence of an active - and therefore ongoing - infection
unlike direct detection by light microscopy or serology, PCR allows a more reliable identification of the causative species infecting the dog
Are there other supportive therapies that could be used for babesiosis?
IVFT if needed
pRBC if v anaemic
The use of immunosuppressant drugs in dogs with
immune-mediated haemolytic anaemia (IMHA) or
thrombocytopenia is controversial - If, despite antiprotozoal treatment, the dog has moderate-to-severe clinical signs (or a high risk for them),
such as sudden collapse or spontaneous bleeding associated with IMHA (e.g. severe spherocytosis, autoagglutination, anti-erythrocyte antibodies or positive Coomb’s or antinuclear antibody tests) and/or immune-mediated thrombocytopenia, the use of 2 mg/kg/day of prednisone is recommended - normally only a 10d course is needed
What is the expected clinical response following the
treatment of babesiosis?
Clinical improvement within 1-7d
Not all survive - severe lab abnormalities = worse px
Some may not fully clear infection which may recrudesce at a later date
Some remain slightly anaemic ongoing
