Babesia microti

Babesia microtiRoss Boreen and Ellyn Krieg

What is Babesia? Definitive Hosts: Ixodes scapularis (Deer Ticks)

Intermediate Host: White footed mouse (Peromyscus leucopus), deer, humans

Found in the U.S. in the Northeast and Midwest

Several different species but we will be focusing on Babesia microti

Interesting Facts Can be co-infected with Lyme’s Disease and

Babesia at the same time Similar structure to malaria so misdiagnosis can

occur Prior to 1969 human cases were rare since then

has been increasing in prevalence In 2009 a record number of 31 babesiosis cases

were reported

Life Cycle

http://www.youtube.com/watch?v=JOakxoorjoQ

Life cycle continued A Babesia-infected tick bites a mouse and sporozoites enter

the mouse’s red blood cycles. The sporozoites become trophozoites and undergo asexual

reproduction (merogony) to produce merozoites. In the RBC’s the merozoites can become male and female

gametes. Another tick then ingests these gametes when it bites the

infected host. The gametes are fertilized in the gut of the tick and the

resulting ookinetes enters the salivary gland. The ookinetes then mature into sporozoites. The tick can then bite a human and introduce the

sporozoites into human erythrocytes. Inside of the erythrocytes they become trophozoites again

and undergo asexual reproduction.

Transmission

Cannot transfer from humans to humans by tick bites only from blood transfusions 159 cases reported from blood transfusions between

1979 and 2009 More than 75% of the cases occurred between 2000-

2009 Mainly in Midwest and Northeast

This makes humans a dead end host Can be passed from mouse to mouse by tick bite

or mouse to human by tick bite

Symptoms Most cases asymptomatic! Symptomatic patients can have fever, headache,

nausea, sweats – closely resembles malaria symptoms Unlike malaria people with sickle cell can still get it

Hemolytic anemia and thrombocytopenia in severe cases RBC fragments can block capillaries in liver, kidneys, and

CNS Immunocompromised and splenectomy patients often

have more severe disease Complications include acute respiratory failure,

congestive heart failure, and renal failure

Giemsa-stained blood smear although a lot of times there is a low parasite count present

Antibody detection: Indirect fluorescent antibody (IFA) test for donated blood and low parasite count cases Also can help differentiate between

Plasmodium and Babesia if questionable

Diagnosis

Treatment Clindamycin plus quinine or atovaquone plus azithromycin

Exchange transfusions for very ill patients

Control

DEET Long, tight clothing when hiking or in areas

with lots of brush Tuck pant legs into boots Walk on clear trails and avoid leaf litter and

overgrown grass where ticks like to be Do tick checks after being outdoors and

remove them right away Need to be attached 24-36 hours before

transmit parasite

Proper Tick Removal When tick is found embedded in the skin, use a fine

pointed tweezers at the point of attachment Using slow, steady, and firm traction pull the tick

straight out, some recommend twisting while pulling Cleanse skin with soap and water Place tick in alcohol. If part of tick remains remove like splinter or leave

alone. DO NOT burn the tick DO NOT squeeze the tick abdomen, it may inject more

potential pathogens.

Review What are some of the symptoms of

Babesia? Babesia has a similar structure to which

other parasite? What kinds of reproduction can Babesia

undergo? Where is Babesia found?

References http://vetmedicine.about.com/od/parasites/ht/

HT_removetick.htm http://dpd.cdc.gov/dpdx/html/Babesiosis.htm http://www.arupconsult.com/Topics/Babesiamicroti

.html http://www.health.state.mn.us/divs/idepc/newslett

ers/dcn/sum09/babesiosis.html