Babesia microtiBabesia microti

Marcus WilliamsonKatie Hofkes

Kayla Jenness

Marcus WilliamsonKatie Hofkes

Kayla Jenness

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 .

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.

General Information

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

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: Martha’s 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.

Geographic Distribution Cont’d

• 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

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 1:1 and it affects

all age groups

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.

Life Cycle

Life Cycle Cont’d.• 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

Life Cylce (Cont’d.)• 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

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.

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.

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.

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.

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.

Pictures

Giemsa-stained thin smear

Pictures Cont’d.Note: the absence of pigment, variation in the rings, and the tetrad on the left, which is helpful for diagnosis of B. microti

Pictures Cont’d.

References

• http://www.itg.be/itg/DistanceLearning/LectureNotesVandenEndenE/imagehtml/ppages/kabisa_1396.htm

• http://www.medterms.com/script/main/art.asp?articlekey=15257

• http://www.dpd.cdc.gov/dpdx/html/Babesiosis.asp?body=Frames/A-F/Babesiosis/body_Babesiosis_page1.htm

• http://www.health.state.mn.us/divs/idepc/diseases/babesiosis/basics.html

• www.healthatoz.com