Babesia
From MalariaETC
Babesia are protozoa transferred by a tick-vector and are acquired most frequently (though not exclusively) in the Americas.
Summary of simple forms
The particular challenge of babesia is their resemblance to the trophozoites of malaria (most specifically P.falciparum). This is important since babesia may be a severe diease and treatment differs https://www.cdc.gov/ticks/tickbornediseases/babesiosis.html
- The most common species in humans (babesia microti) has the appearance of a “ring”
- May involve fewer than 1% of erythrocytes or up to 80%
- Rings resemble P. falciparum: small and fine with accole forms and multiple parasites within a single cell
Distinguishing babesia trophozoites from malaria
- Typically, size and form vary more significantly than in malaria
- Pigment is not seen at any developmental stage
- Extra-erythrocytic forms (single or clumped) are often present
Summary of complex forms
Babesia is frequently associated with complex parasite forms within cells. These may include:
Extracellular forms
- Single free parasites
- Masses of parasites clumped together
Asexual forms
Asexual replication (similar to schizonts of malaria) with two division cycles forming up to four separate daughter parasites:
- Tetrads of merozoites arranged in the form of a ‘Maltese Cross’ (characteristic but rare)
- More often a complex of fine elongated or ring forms occurs within a single cell
- These may be difficult to distinguish from multiply infected cells
- In contrast to malaria, pigment is not seen
Sexual forms
- Gametocytes remain intra-erythrocytic, becoming more solid and larger than typical rings, these forms are often infrequent.
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