Question

Human Babesiosis is an apicomplexan parasite similar to the parasites that cause malaria. Able to infect either humans or livestock, what is unique to the transmission cycles for human or veterinary transmission? How do these parasites produce disease-causing symptoms?

 

Answer 1

Babesiosis is zoonotic disease that is caused by protozoa of Babesia species. Its life cycle involves two stages.

The asexual reproduction occurs within mammalian erythrocyte while the sexual reproduction occurs within arthropod vector.

The unique factor regarding the transmission cycle to human is that, they are obligate parasites of RBC. And the speciality is that, while inside the vector,the parasite requires RBC's to mature itself into mature stages. ie; it requires blood meal.

The major symptoms of the disease include hemolytic anemia ( destruction of Red Blood Cells), fever with intermittent chills or sweat, Fatigue, vomiting, abdominal pain etc.. The parasite produces disease causing symptoms by invading Red Blood Cells. VMSA or Variabe Merozoite Surface Antigen of the parasite is capable of attaching free merozoites to red blood cells where the parasite is able to reproduce by binary fission. This eventually causes the loss of membrane integrity of RBC and this ultimately results in hemolytic anemia.

In addition, Variant Erythrocyte Antigen 1 (VESA 1) promotes the adherens of infected RBC to vascular endothelium which facilitate the persistent infection of the parasite by reducing access to immune cells of host and also prevents the removal of infected erythrocytes in spleen (one of the major function of spleen is to remove old and damaged blood cells).