Babesia microti

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Babesia microti

• Marcus Williamson
• Katie Hofkes
• Kayla Jenness

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General Information

• Hemoprotozoan infection of the red blood cells
• Babesiids are pyriform, round, or oval parasites
• Spread to humans by a tick bite, Ixodes
  scapularis .

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General Information

• The disease mostly effects people who are
  immunocompromised, elderly, or have undergone a
  splenectomy
• Approximately 20 of patients diagnosed with
  Babesiosis also have Lyme disease from the same
  deer tick bite.
• While more than 100 species of Babesia have been
  reported, only a few have been identified as
  causing human infections.

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General Information

• Their apical complex is reduced to a polar ring,
  rhoptries, micronemes, and subpellicular
  microtubules

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Geographic Distribution

• Is found worldwide
• Babesia microti is most commonly found in the
  Northeast and Midwest in the United States and
  often in nonsplenectomized patients
• In the Northeast Marthas Vineyard, Nantucket
  Island, Cape Cod, Long Island are the most common
  places
• In the Western US, the causative agent of
  Babesiosis is Babesia gibsoni
• There have been cases in Minnesota and Wisconsin
  as well.

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Geographic Distribution Contd

• Not much is known about Babesia in
  Malaria-endemic countries
• In Europe, most reported cases are from Babesia
  divergens and is found in splenectomized patients
• In the Southern United States, the infection is
  called Babesia bigemina, which is a disease of
  cattle
• Also called Texas red-water fever

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Mortality/Morbidity

• Death in the US is uncommon
• Most infections are asymptomatic and improve
  spontaneously without treatment
• About 25 of patients with Babesiosis also have
  Lyme disease
• In Europe, Babesiosis is more serious
• 84 are asplenic and 53 become comatose and die
• Male to Female ratio is 11 and it affects all
  age groups

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Hosts

• Definitive Host- White footed mouse (Peromyscus
  leucopus)
• Intermediate Host- Deer Tick (Ixodes scapularis)
• Accidental Host Humans (Dead end host)
• Deer are the hosts which adult ticks feed on but
  are indirectly part of the life cycle.

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Life Cycle
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Life Cycle Contd.

• During a blood meal, a Babesia infected tick
  introduces sporozoites into the mouse host
• Sporozoites enter the erythrocytes and undergo
  asexual reproduction
• In the blood, some parasites differentiate into
  male and female gametes
• Once ingested by a tick, the gametes unite and
  undergo a sporogenic cycle resulting in
  sporozoites

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Life Cylce (Contd.)

• Humans become a part of the cycle when bitten by
  infected ticks
• During a blood meal, the Babesia infected tick
  gives sporozoites to the human host
• Sporozoites enter the erythrocytes and undergo
  asexual reproduction
• Humans are dead end hosts and there is little, if
  any more transmission that occurs from ticks
  feeding on infected humans

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Pathogenesis/Clinical Signs

• Majority of people have no visible symptoms
• Fever, chills, sweating, fatigue
• Flu-like, tiredness, loss of appetite, muscle
  pain, nausea, vomiting, headache, shaking chills,
  blood in urine, and depression can occur.
• Hepatosplenomegaly
• Hemolytic Anemia
• These can occur for several weeks after an
  incubation period of 1-4 weeks
• Those over 40 who have had spleen taken out or
  have serious disease may end up with 85 blood
  cells infected which leads to possibly death.

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Diagnosis

• Early diagnosis can reduce the severity of the
  illness.
• Some people may be infected with more than one
  tick-borne infection which will make diagnosis
  more difficult.
• Examining thick and thin blood smear samples
  stained with Giesma is the most common way for
  diagnosis.
• Antibody detection by indirect fluorescent
  antibody (IFA) test is a diagnostic test.
• Isolation of Babesia by inoculation of patients
  blood into hamsters and gerbils assists in
  diagnosis also.

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Treatment

• Treated with antimicrobial drugs.
• Combination of clindamycin, quinine, atovaquone,
  and/or azithromycin
• Clindamycin is by injection and quinine given
  orally 3-4 times a day for 4-7 days.
• Exchange transfusions have been used for the
  severely ill patients.

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Control Measure

• Avoid tick habitats during the peak time of the
  year (when deer populations increase)
• Stay on trails when walking through the woods.
• Avoid tall grasses.
• Wear long sleeved shirts and tuck pant legs into
  socks.
• Wear insect repellent.
• Check for ticks after an outing.

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Tick Removal

• Use pair of tweezers to grasp the head of the
  tick.
• Grasp tick close to the skin.
• Pull tick outward slowly, gently, steadily.
• Do not squeeze the tick.
• Use antiseptic on the tick bite.

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Pictures
Giemsa-stained thin smear
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Pictures Contd.
Note the absence of pigment, variation in the
rings, and the tetrad on the left, which is
helpful for diagnosis of B. microti
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Pictures Contd.
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References

• http//www.itg.be/itg/DistanceLearning/LectureNote
  sVandenEndenE/imagehtml/ppages/kabisa_1396.htm
• http//www.medterms.com/script/main/art.asp?articl
  ekey15257
• http//www.dpd.cdc.gov/dpdx/html/Babesiosis.asp?bo
  dyFrames/A-F/Babesiosis/body_Babesiosis_page1.htm
  
• http//www.health.state.mn.us/divs/idepc/diseases/
  babesiosis/basics.html
• www.healthatoz.com