My presentation on Babseiosis

1. Babesiosis

2.  Introduction
 History
 Classification
 Structure
 Lifecycle
 Epidemiology
 Pathogenesis
 Clinical features
 Diagnosis
 Treatment
 Animal models
 Prevention

3. Introduction
• Infection due to parasites belonging to genus Babesia
•
•
•
•
•
•
•
B. microti
B. divergens
B. duncani
WA-1
MO-1
KO -1
EU-1
• Obligate intracellular: RBCs
• Requires both a competent vertebrate and nonvertebrate
host to maintain transmission cycles
• Transmitted by ixodid ticks to their vertebrate hosts

4. History
Theobald Smith (July 31, 1859 – December 10, 1934) Along with
Kilbourne Discovered arthropod borne transmission in 1893
Cattle Febrile heamturia : Bloodied waters of
Egypt

5. History
 1957- 1st human case- Yugoslavian farmer
 1968- 1st recognized in California (USA)
 1976- Ixodes dammini identified as vector for B.
microti
 1993- 1st description of WA-1
 1996- 1st description of MO-1

6. Classification
 Taxonomic Classification
 phylum Apicomplexa (also called Sporozoa),
 class Aconoidasida (Piroplasmea)
 order Piroplasmida
 families Babesiidae and Theileriidae;

absence of a preerythrocytic cycle in Babesia and the absence
of transovarial transmission in Theileria.

7. • Initially, Babesia species identified - morphological
parameters of the intraerythrocytic forms
(i.e., trophozoites)
• This analysis, along with host specificity, has provided
> 100 species of Babesia
• 7 spp. affect humans

8. Large(2.5-5µm)
Transovarial
Small (1.0–2.5µm)
Transstadial
Babesiosis, HOMER et.al. CMR, July 2000, p. 451–469

9. Structure

10. Lifecycle
Reservoir
White tailed deer
For all except
B. meri
ornithodorrus

11. Epidemiology
WA-1
B. microti 300
cases
 Temperate climates
B. divergens

12. Epidemiology
 Frequency of B. microti & WA-1 in US > reported cases

because self- limiting & mild in humans
 Mortality in USA – 5%
 Survey in California – 16% prevalence WA-1
 Survey of Blood donors - 3-8% prevalence B. microti
 Human cases of B. microti reported
Coastal areas of southern New England
 Eastern Long Island
 Minnesota
 Winsconsin

 WA-1 – throughout pacific coasts
Babesiosis, HOMER et.al. CMR, July 2000, p. 451–469

13. Contd..
 Sporadic cases – Europe (France & British Isles),
Africa, Asia
• Cattle Babesia (B. divergens, B. microti)
 83% Babesiosis in Europe - B. divergens
 Mortality rate – 42% Europe
 Few cases reported – China, Taiwan, Egypt, S. Africa,
Mexico
 Transfusion- acquired Babesia several cases in USA,
but none in Europe & elsewhere

14. India
 Single case report
 51 year old patient from Madhya Pradesh
 History
 Working nursing home in gwalior
 Fever, vomiting, headache, arthralgia
 No h/o tick bite or visit to endemic area
 No other family member
 No h/o splenectomy or blood transfusion
IJMM 2005;23:267-9

15.  O/E
 Liver and spleen palpable
 Scleral icterus, passed dark coloured urine
 Investigations
 WBC count 1,900/cumm
 Platelet count 55,000/cumm
 LDH raised

16.  Peripheral blood smear – ring forms varied greatly
confused P. Falciparum
 Antimalarial treatment – no response
 Smear reviewed – pear shaped, tetrad - babesiosis
suspected
 HRP II – negative
 Quinine + clindamycin – Pt. afebrile within 2 days

17. Pathogenesis
Env
Host
Agent

18.  Modification and rupture of RBCs

Replication neoAg`s d/t membrane alteration

Docking sites for IgG and complement
 phagocytosis in spleen  Anemia
 Lack of periodicity: Asynchronous replication
 More severe manifestations in immunosuppresed and
elderly

20. • establishment stage antibodies (IgG) play a role in
preventing erythrocyte infection by binding the free
sporozoites.
• progression stage organisms invade erythrocyte
– innate immune system control growth rate of the merozoites
– NK cells and macrophages - soluble factors: IFN-g by NK
cells and TNF-a, nitric oxide (NO), and ROSs by macrophages
(Mf).
• resolution stage decrease in parasite numbers -
intracellular degeneration inside the erythrocyte, as
evidenced by the appearance of crisis forms.

21. Clinical features
• Disease manifestations asexual reproductive stage
• Predisposing factors +/• Mild to severe illness
– Generalized weakness
– Fever
– Gastrointestinal symptoms (anorexia, nausea, abdominal
–
–
–
–
–
–
pain, vomiting, diarrhea, etc.)
Headache
Myalgia
Weight loss
Arthralgia
Respiratory symptoms (cough, shortness of breath, etc.)
Dark urine

22. Clinical examination
 Hepatomegaly and splenomegaly
 Hemolytic anemia - lasts from several days to few
months occur in clinically severe cases, most
commonly in asplenic or elderly

23.  Pulmonary manifestations - rare in babesiosis, but
non-cardiogenic pulmonary edema (NCPE) is the most
frequent manifestation
 not related
 degree of parasitemia
 splenic function and its onset may be early or late
 16 reported cases - reviewing the literature on the
pulmonary complications

24. Common Complications
 Acute respiratory distress syndrome
 Anemia requiring transfusion
 Congestive heart failure
 Disseminated intravascular coagulation
 Hypotension/shock
 Myocardial infarction
 Renal failure

25. HUMAN COINFECTION
• Coinfection with B. microti & other tick-borne
pathogens, particularly B. burgdorferi (Lymes disease)
•
serosurveys - 13% of Lyme disease patients in babesia-endemic
areas are coinfected with B. microti
• B. microti is transmitted by the same Ixodes tick that
perpetuates the agents of
Lyme disease
• human granulocytic ehrlichiosis
• novel Bartonella species
•
• P. leucopus is also the vertebrate reservoir for at least
three of the known pathogens

27. • Patients coinfected with B. microti and B. burgdorferi
experience
•
•
more severe symptoms, resulting in fatality in rare cases
persistence of postinfectious fatigue.
• B. burgdorferi DNA persisted for prolonged periods
• B. microti - no significant effect on the duration of
parasitemia

28. Blood
transfusion
Splenectomy
Tick bite
Travel
history
Clinical
presentation
Diagnosis
Age

29.  A positive Coombs test in combination with hemolytic
anemia & elevated procalcitonin levels is highly
suspicious of babesiosis
 Laboratory tests
 examination of stained blood smears
 serologic evaluation with indirect (immuno) fluorescent
antibody tests (IFATs)
 PCR

30.  Examination of thin blood
smears
 most frequently used technique
 Wright’s or Giemsa stain
 simple rings (annular),
 pear-shaped (pyriform),
 Maltese cross (tetrad form)
 High parasitemia present during
acute infections

varying from 5 to 80% of
erythrocytes

31. • Duration of detectable parasitemia on blood smears
varies
•
3 weeks to 12 weeks with the longest duration of smear
positivity being 7 months for a splenectomized patient
• Quantitative buffy coat system (QBC) – Merozoites
stained with acridine orange
•
•
Simple & rapid
Showed 100% correlation with blood smear exam.
(Mattia et al, 1993)

32.  Distinguishing features differentiate the two
organisms.
 Babesial organisms usually form tetrads ("Maltese
cross"),
 Do not have hemozoin pigments within the affected red
blood cells
 Have extracellular merozoites

33. Serodiagnosis
 IFATs - B. microti infections, chronic infections
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
Hamster-derived B. microti Ag
Distinguish between B. microti, WA-1, B. divergens
Specific and sensitive
Diagnostic titers above 1:64
Higher cutoff titers (1:128 to 1:256) greater diagnostic
specificity
IgM and IgG
Problematic in HIV, splenectomy
Time consuming & labor intensive

34. IFAT
 Antibody titers can remain elevated for as long as 13
months to 6 years after infection
 Although persistence of antibody does not necessarily
reflect a measurable infection, levels of IgG antibody
decline less rapidly in persistently infected patients

35. ELISA
 ELISA – Recombinant antigen - 4 antigens used




rBMN1-2
rBMN1-15
rBMN1-17
rMN-10
- 27/40
- 27/40
- 27/40
- 27/40
 Showed high sensitivity & specificity
 Soluble whole parasite antigen (B. divergens)
Loades et al, 2000

36. Problem associated with
serological tests
•
Relationship between antibody titers, the presence of
parasites, and the state of protective immunity is not clear
•
Antibodies may persist for long periods after the disease has
cleared
•
Overestimate of disease prevalence
•
Antibody titers may be observed in the absence of protective
immunity

37. PCR assay
• Based on universal primer amplification of a fragment
of the small subunit rRNA gene
• Highly conserved among babesias
• Heterologous between Babesia spp. and other
intraerythrocytic protozoal parasites as well as within
the genus Babesia itself
• Distinguishes readily between B. divergens, B.
microti, and Plasmodium spp., it provides a valuable
adjunctive

38.  Advantages over IFA testing.
 Less time consuming
 conducted by generalist technicians
 more readily be standardized
 sensitivity and specificity comparable to those of
conventional IFAs

39. MASP(microaerophilous stationary
phase) culture technique

Quantities of parasite nucleic acid needed for defining
phylogenetic relationships of these species,

Methods for detection of the parasite in otherwise
asymptomatic individuals

Producing parasite antigens

Attenuated strains of Babesia - immunization.

40. Laboratory diagnosis
• B. microti immunoblot kits
• Animal Inoculation
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•
•
2-4 weeks
Sensitive (300 org./ml blood)
Time consuming, expensive

41. Animal models
 Rats
 BALB/ c mice
 Splenectomized calves
 Gerbils

42. Treatment

43.  Imidocarb and the combination of oxomemazine and
phenamidine were most effective in vitro
 Imidocarb, although not licensed for human use, most
effective agent for treating B. divergens infections in
cattle
 other pharmacologic interventions -
chloroquine, tetracycline, primaquine, sulfadiazine, an
d pyrimethamine

44. Prevention
• Avoidance of or minimization of exposure to tick•
•
•
•
infested areas
Ase of tick repellents before entering a tick-infested
area thorough examination of skin after exposure.
Ticks found before attachment -removed, and
Ticks found after attachment removed within 24 h
limit the possibility of transmission
Application of pesticide to host nests and on the coats
of reservoir hosts can interrupt transmission

45. Vaccines
 Live vaccines

living parasites cattle
 Recombinant vaccines



B. bovis & B. bigemina vaccine cattle
Soluble parasite antigen (SPA)
No effective B. microti vaccine
 Human vaccines – Expt. Stage


MRA gene (Maltase cross form-related antigen)
37 kDa glycoprotein (Bd37)

46. Summary
 Emerging disease
 Common in the Americas
 Can be confused with plasmodium falciparum
infection
 Diagnosis requires high index of suspicion
 Treatment involves use of At or Az or Clin + Quin

47. Thank you