babesia microti ross boreen and ellyn krieg. what is babesia? definitive hosts: ixodes scapularis...
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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 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