Wednesday, April 23, 2008


A 50 year old presents to your office after a recent trip to Cape Cod. He reports fever, night sweats, myalgia, arthralgia, nausea, vomiting, and fatigue. On exam, you note hepatosplenomegaly. Lab findings show anemia, thrombocytopenia, and conjugated hyperbilirubinemia. Frustrated with these non-specific findings, you order a blood smear, shown above.

Challenge: What is the vector for this disease?

Image shown under fair use.


Alex said...

vector would be a tick, not sure if it matters which type.

mika said...

Babesia carried by the ixodes tick

What will the Cape Cod tourism bureau think of this posting?

Craig said...

yep! i was surprised to find out it was a tick vector.

Craig said...


The blood smear has a “Maltese cross,” pathognomonic for babesiosis. Caused by Babesia microti (and B. divergens), this is a tick-borne illness that resembles malaria and is transmitted from its animal reservoir to humans by the tick vector Ixodes scapularis (the same vector as Lyme disease and ehrlichiosis). The protozoa infect RBCs, causing hemolysis. Wright or Giemsa stained peripheral blood smear showing intraerythrocytic parasites is the definitive diagnosis. Though there are many appearances, tetrads of merozoites forming maltese crosses is specific to Babesia. In the U.S. it occurs predominately in the Northeast coast.

Sources: UpToDate;