Blood and tissue flagellates (1).ppt full

blood and tissue flagellates

1. Blood and Tissue Flagellates (Hemoflagellates)
Flagellated protozoan parasite
Inhabit blood and tissue of humans and other animal reservoir
host.
Six genera but only two of them are responsible to cause disease
to human and livestock (zoonoses)
GenusGenus Trypanosoma
GenusGenus Leishmania
 Belongs to: Phylum SarcomastigophoraPhylum Sarcomastigophora
Order KinetoplastidaOrder Kinetoplastida
Family TrypanosomatidaeFamily Trypanosomatidae

2. Blood and Tissue Flagellates (Hemoflagellates)
The medically important kinetoplastids are:
Organism Disease Vector
African
trypanosomes
African trypanososmiasis
(African sleeping
sickness)
Glossina species (tse tse
fly)
American
trypanosomes
(T. cruzi)
Chagas’ disease Triatomine bugs
Leishmania
species
Leishmaniasis
(Cutaneous or visceral)
Phlebotomus (sand fly)
and Lutzomyia (sand fly)

3. Blood & tissue flagellates
General Characteristics:
Reproduces by simple longitudinal binary fission
Two hosts required:
Vectors (tse tse fly and sand fly) as intermediate hosts
Human /other RH as definitive host
The species are morphologically indistinguishable
However, they can be differentiated on the basis of their:
Clinical features
Geographical distribution
Immunological tests… etc.

4. Occur in a variety of stages in the human host & the insect vector
Occurs both in flagellate & non-flagellate forms
The basic morphological stages are:
Amastigote
Promastigote
Epimastigote
Trypomastigote
Blood and Tissue flagellates
Blood & tissue flagellates: morphology

5. The different developmental forms are differentiated on the basis
of:
1.Presence or absence of free flagellum
2.Presence or absence of undulating membrane
3.Position of the kinetoplast relative to the nucleus.
Consists: Nucleus, Kinetoplast, axoneme and may have single
flagellum& undulating membrane
Distinguishing feature – kinetoplast
Blood and Tissue flagellates
Blood & tissue flagellates: morphology

6. The following are the main developmental forms:
1.Amastigote (Leishmanial form)
Rounded body, central single nucleus and eccentric
kinetoplast visible
No free flagellum (non – motile)
No undulating membrane
The only intracellular forms of all leishmania species and
Trypanosome cruzi.
Blood and Tissue flagellates
Flagellum
Kinetosome
Kinetoplast
Nucleus

7. 2.Promastigote (Leptomonad form)
Elongated body, central single
nucleus, anterior kinetoplast
Single anterior flagellum arises from
kinetoplast (motile)
No undulating membrane
found in the invertebrate host, and in
culture media (of all Leishmania
species) and in man for Tryponosoma
cruzi
Blood and Tissue flagellates
Flagellum
Kinetosome
Kinetoplast
Nucleus
anterior
posterior

8. 3.Epimastigote /crithidial/ forms
Elongated body, single free
flagellum (motile), single nucleus
Has undulating membrane,
kinetoplast is just anterior to the
nucleus
 found in the invertebrate host and
in culture media (of Trypanosome
species)
Blood and Tissue flagellates
Posterior
Anterior
Undulating
membrane

9. 4.Trypomastigote (Trypanosomal form)
Pleomorphic, it can be as “U” or “C” shaped,
Central single nucleus, posterior kinetoplast
Single Flagellum arises posteriorly (motile)
The kinetoplast found at the posterior end relative
to the nucleus.
Has undulating membrane
Found in the peripheral blood of vertebrates and is
the diagnostic stage of Trypanosome species.
Blood and Tissue flagellates

10. 5.Metacyclic Trypomastigote (Trypanosomal Forms)
Morphologically similar to trypomastigote stage but it is
short and stumpy
Single nucleus
Final developmental stage in the gut of the insect vectors
Infective stage of Trypanosomes species
Motile
Blood and Tissue flagellates

11. Leishmania species:
Causative agent of Leishmaniasis
Obligate intracellular protozoa of the genus Leishmania
•In the human host, Leishmania are intracellular parasites that
infect the mononuclear phagocytes.
Named after Leishman, who first described it in London in May
1903
In the human host, Leishmania are intracellular parasites that
infect the mononuclear phagocytes
Vector born disease transmitted by sandflies (genera Phlebotomus
and Lutzomyia)
The spectrum of human disease ranges from
•Self-healing localized ulcers to widely disseminated
progressive lesions of the skin, mucus membranes, and
•The entire reticuloendothelial system
Blood and Tissue flagellates

12. Epidemiology:
Human infection is caused
by about 21 of 30 species
that infect mammals.These
include:
L. donovani complex with 3
species
L. donovani,
L. infantum,
 L. chagasi;
L. mexicana complex with 3
main species
L. mexicana,
L. amazonensis,
L. venezuelensis
•L braziliensis complex
–L braziliensis
–L. peruviana.
•L. Guyanensis complex
–L. Guyanensis
–L. panamensis
•L. tropica;L. major & L.
aethiopica belongs to a
separate complex of
the same name 
Blood and Tissue flagellates: Leishmania

13. Leishmaniasis present itself in various disease manifestations
and therefore can easily be classified clinically as
1.Visceral leishmaniasis
2.Cutaneous leishmaniasis
3.Mucocutaneous leishmaniasis
4.Diffuse cutaneous leishmaniasis
These different forms of the disease is caused by the different
species of Leishmania
Blood and Tissue flagellates: Leishmania

14. 1.Cutaneous leishmaniasis:-
L. tropica
L. major
L. aethiopica
L. panamensis
L. guyanensis
L. Peruriana
2.Visceral leishmaniasis:-
L. donovani
L. infantum
 L. chagasi
3.Mucocutaneous leishmaniasis
–L. panamensis
–L. guyanensis
–L. brazilliensis
4.Diffuse cutaneous
leishmaniasis
•L. amzonensis
•L. aethiopica
Blood and Tissue flagellates: Leishmania

15. Distribution:
Endemic in at least 88 countries (16 developed and 72
developing countries) on 5 continents:
Africa, Asia, Europe - Old world
 N. America, and S. America- New world
350 million people are at risk of infection
12 million infected/year
1.5-2 million clinical cases/year
90% of CL occurs in Afghanistan, Iran, Saudi Arabia, Syria,
Brazil and Peru
90% of all VL occurs in Bangladesh, Brazil, India, and the
Sudan
90% of MCL occurs in Bolivia, Brazil and Peru
Blood and Tissue flagellates: Leishmania

16. Distribution in Ethiopia:
Four species of Leishmania found:
L. aethiopica, L. major, L. tropica,
L. donovani,
Visceral leishmaniasis (VL)
Occurs mainly in arid and
semiarid lowlands below 1,300 m
altitude
Important endemic foci include
Gelana focus at lake abaya,
The segen valley (Aba- Roba
focus) in Konso Wereda
The Omo river plains and
Metema and Humera plains
•Cutaneous leishmaniasis
–Endemic at altitudes
between 1400 and 2700
m in most administrative
regions
–Prevalence rates of 5.5 –
40% were reported from
villages in:
–Shewa , Wello and
G.Gofa with the
highest rate in
Ocholo village in G.
Gofa.
Blood and Tissue flagellates: Leishmania

17. Global Status
L. donovani L. donovani
L. infantumL. infantum
L. tropicaL. tropica
L. major L. major
L. aethiopicaL. aethiopica
Old world:
(Asia, Africa, Europe) New world:
(South and Central America)
L. infantum
( L. chagasi )
L.mexicana
L.brazilliensis
L. peruriana
L.panamensis
L.guyanensis
L.amzonensis

18. Transmission:
Common mode of transmission is by the bite of sandfly
oPhlebotomus in Old world
oLutzomyia in New world
Uncommon modes of transmission:
oCongenital transmission
oBlood transfusion
oRarely, inoculation of cultures
Blood and Tissue flagellates: Leishmania

19. Two morphological forms:
1.Promastigote
2.Amastigote
Blood and Tissue flagellates: Leishmania

20. 1.Female sandflies inject the
Metacyclic promastigotes
during blood meals
2.Promastigotes are
phagocytized by
macrophages & transform
into intracellular amastigotes
form
3.Amastigotes multiply by
binary fission within
macrophage
4.Rupture from macrophages
5.Amastigotes infect new cells
(phagocytosis of amastigotes)
or ingestion by vector
Life Cycle…

21. In VL the amastigotes are carried through blood circulation ,
then invade and multiply in the macrophages of spleen, liver,
Bone marrow, lymph glands , etc.
In Cl , MCL – the amasigote multiply in skin macrophages
(histocytes)
6.Sandflies become infected during blood meals when they ingest
macrophages infected with amastigotes
7.The host cell (macrophage) break down and releasing the
amasigotes which is then transform to procyclic promastigotes
8.Procyclic promastigotes multiply , fill the lumen of the gut and
attaches to epithelium and becomes metacyclic promastigote
and migrate to the proboscis
Life Cycle…

23. Clinical features and pathology
1.Cutaneous leishmaniasis (CL)
Most common form
 Relatively benign self-healing skin lesions (localized/simple
CL)
2. Diffuse cutaneous leishmaniasis (DCL)
Rare cutaneous infection with non- ulcerating Nodules
resembling lepromatous leprosy
Seldom heals without treatment
3.Mucocutaneous Leishmaniasis (MCL)
Simple skin lesions that metastasize to mucosae especially
nose and mouth region
4.Visceral Leishmaniasis (VL)
Generalized infection of the reticuloendothelial system, high
mortality response

24. Cutaneous Leishmaniasis
Causative agents Causative agents
Leishmania tropica
Leishmania major
Leishmania aethiopica
Leishmania mexicana
Leishmania peruriana
Leishmania panamensis
Leishmania guyanensis

25. 1.Cutaneous Leishmaniasis
•Incubation period: 2 weeks to several months
•Initially, the lesion is a single small, red
papule up to 2 cm in diameter
•Occasionally satellite lesions
•Change in size and appearance over time
•Chronic ulcerated, papular, or nodular lesion
•Lesion is painless, non-tender, non-pruritic
and usually clean
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26. 1.Cutaneous Leishmaniasis
•Self-healing, months to years
•Sores can leave significant scars and be disfiguring
if they occur on the face
•Metastasis via blood or lymphatic systems
(especially L. braziliensis)
•Often described as looking somewhat like a
volcano with a raised edge and central crater
•Occasionally palpable lymph nodes
•The clinical forms of CL vary according to the
species of parasite, Region and Response of patient

27. a)Old World CL: L. tropica (SW Asia, N.Africa)
•Dry urban oriental sore
•Dry painless lesion
b)Old World CL: L. major (Central Asia, middle East, Africa)
•Rural wet oreintal sore (moist
lesions or open with
seropurulent exudate)
c)Old World CL: L. aethiopica (highlands of Kenya and Ethiopia)
•Similar to oriental sore
•Can cause DCL

28. 2.Diffuse Cutaneous Leishmaniasis
•Lesion develop over large areas of the body
•Scaly, not ulcerated, nodules
•Chronic and painless
•Numerous parasites in lesions
•Seldom heal despite treatment

29. 3.Mucocutaneous Leishmaniasis
•Primarily L. braziliensis (espudia)
•Two stages
•Simple skin lesion
•2
o
mucosal involvement
•Variable types and sizes of lesions
•Ulcerative type
•Rapid and extensive mutilation
•Non-ulcerative type
•Local edema (upper lip)
•'tapir' nose
•Metastasis via blood or lymphatic
systems
•Frequently in naso-pharyngeal
mucosae (Junction of skin and
mucosa)

30. 4.Visceral Leishmaniasis
Caused by the Leishmania donovani complex,
•Leishmania donovani
•L. infantum
•L. chagasi
•Reticuloendothelial system affected
•Spleen, liver, bone marrow, lymph nodes
•Progressive disease
•75-95% mortality if untreated
•Death generally within 2 years (due to severe secondary
bacterial infections in advanced disease)
•Pneumonia is the common complication

31. Clinical Presentation:
•Incubation period
•Generally 2-6 months
•Can range 10 days to years
•Fever, malaise, weakness
•Wasting despite good appetite
•Spleno- and hepatomegaly,
enlarged lymph nodes
•Depressed hematopoiesis
•Severe anemia
•Leucopenia
•Thrombopenia  petechial
hemorrhages in mucosa
Visceral Leishmaniasis

32. Post Kala Azar Dermal leishmaniasis (PKDL)
Characterized by hypo pigmented and raised
erythematous patches on the face, trunk of the
body and limbs
May develop in to nodules and resembles those
of lepromatous leprosy, fungi infections or other
skin disorders
Occasionally there is ulceration of lips and
tongue
Occurs in 1-3% of Indian and 50% of Sudanese
VL patients
It require expensive and prolonged treatment
Easily cured with treatment (in contrast to DCL)

33. Diagnosis of CL, MCL, DCL
•Suspected because of:
•Geographical presence of parasite
•History of sandfly bite
•Skin lesion:
•Chronic, painless, ‘clean’ ulcer
•Nasopharyngeal lesions
•Nodular lesions
Methods of Diagnosis:
1.Demonstration of parasite
•Amastigotes (scrapings, biopsy,
aspirates)
2.Culture from ulcer material
3.Leishmainin test (montenegro test)
•Promastigote antigen injected
(postive if > 5mm)
4.Serology?
Make incision in
active part of lesion
Scrape cells
from incision
Prepare Giemsa-
stained smear
Amastigote
stage

34. Treatment
•Sodium stibogluconate (Pentostam)
•Pentamidine isethionate
•Amphotericin B
•Cryotherapy and thermotherapy
Treatment

35. Prevention and control
1.Early detection by serological diagnosis (VL) and treatment of
infected persons
2.Personal protection from sandfly bites by:
Using insect replants
Avoiding endemic areas especially at times when sandifies are most
active
Use of pyrethroid impregnated bed nets and curtains
3.Vector control by the use of light traps, sticky paper traps, or
residual insecticide spraying of houses

36. 4.Destruction of stray dogs and infected domestic dogs
5.Elimination and control of rodents
6.Sitting human dwellings away from the habitats of animal reservoir
hosts where sandifies are known to breed
Prevention and control

37. The Trypanosomes

38. Trypanosomes
General Feature
Actively motile flagellated protozoa that live in blood and lymph
node
Vector:- tsetse fly, bug
Classification of human trypanosomes
Genus Trypanosoma has abundance of species parasitizing the
blood and tissues of vertebrate hosts and are called
haemoflagellates.
The major difference between the two genera (viz. Leishmania
and Trypanosoma) is:
The primary diagnostic form found in Leishmania is the
amastigote
Whereas that of Trypomastigote (with the exception of T.
cruzi, in which case the amastigotes may also be found)

39. Trypanosomes
Very few infect humans
Trypanosoma brucei variants (cause African sleeping sickness)
T. b. gambiense
T. b. rhodesiense
Trypanosoma cruzi (cause Chagas’ disease or American
Trypanosomiasis)
Trypanosoma rangeli (cause T. rangeli infection)
These species are distinctly different forms of trypanosomes varying
considerably in:
Mode of transmission
Geographic distribution
Clinical presentations

40. Trypanosomes
Organism Disease Vector Transmission
T. b.
gambiense
West African
sleeping sickness
Glossina – tsetse
fly
“Bite” – saliva
T. b.
rhodesiense
East African
sleeping sickness
Glossina – tse tse“Bite” – saliva
T. cruzi American
Trypanosomiasis
or Chagas’
disease
Reduviid bug
(kissing bug)
(cone nose bug)
Feces of infected
Reduviid bug in
to the “bite”
T. rangeli T. rangeli
infection
Reduviid bug
(kissing bug)
(cone nose bug)
“Bite” – saliva

41. Trypanosomes
Based on their development in the insect vectors and their mode of
transmission, trypanosoma are grouped into two.
1.Salivarian group. The parasites develop in to the mid end fore gut of
their vectors and transmission to man by inoculation of the parasites
Trypanosoma gambiense
Trypanosoma Rhodesians
2.Stercorarians group. The parasites develop in the hind gut of their
vectors and transmission to man by the contamination of bite areas
with faeces of their vectors
Trypanosomes cruzi

42. African Trypanosomiasis
The parasites responsible for causing African sleeping sickness
belong to a group of closely related trypanosomes in the
Trypanosoma brucei species complex.
Three morphologically indistinguishable subspecies are
recognized:
1.T. brucei brucei- infects game animals/ domestic livestock (causes
nagana) in Africa
T. brucei is a natural parasite of wild game in Africa and are non-
infective to humans. This inability to infect humans is due to a
‘trypanosome lytic factor’ found in human sera.
1.T. b. rhodesiense- causes E. African Trypanosomiasis
1.Rhodesia is former name for Zimbabwe
2.T. b. gambiense- causes W. and Central African sleeping sickness
Glossina (tsetse) fly serves as vector (IH) which breed mostly in
the moist areas around river banks.

43. NB: It is believed that T. gambiense has been associated with
humans for much longer than T. rhodesisense and thus possibly
accounts for the lower virulence of T. gambiense.
Transmission (except the vector strains involved), life cycle
(except the RHs involved), Lab diagnosis, treatment and
prevention are similar in both cases.
They may differ in pathogenesis and clinical presentations.
African Trypanosomiasis

44. African Trypanosomiasis: Life Cycle
Vector
Human
VSG
lost
Antigenic Variation (VSG
gene expressed)
Only LS form
replicative
Salivary gland

45. African Trypanosomiasis: Life Cycle

46. African Trypanosomiasis: Disease Course
Infection with African trypanosomes can result in disease
manifestations ranging from asymptomatic or mild to a severe
fulminating disease.
T. rhodesiense is more likely to cause a rapidly progressing and
fulminating disease than T. gambiense.
T. gambiense tends to cause a slow progressing disease which may
either be self-limiting or develop into a chronic disease involving the
lymphatics and the central nervous system (CNS).
African trypanosomes show antigenic variation

47. African Trypanosomiasis: Disease Course
1.At bite site
Local inflammatory nodule
(chancre)
During the incubation period (1-
2 weeks)
2.Acute blood stage
The trypomasigotes will
invade the capillaries and
enter the circulatory system
(replicate)
Characterized by irregular
episodes of fever and
headache.

48. African Trypanosomiasis: Disease Course
3.Lymphatic stage
Often in T. gambiense infections.
Symptoms include:
Enlarged lymph nodes
Weight loss
Weakness, rash, itching, and edema
Continued intermittent febrile
attacks.
Higher parasitemias are often
associated with the symptomatic
periods.
Little evidence of lymphatic
involvement in T. rhodesiense
infections.

49. African Trypanosomiasis: Disease Course
4.CNS involvment
A hallmark feature of African trypanosomiasis is the invasion
of the CNS and nervous system impairment.
Nervous impairment include: apathy, fatigue, confusion,
somnolence, and motor changes (such as tics, slurred speech,
and incoordination).
The changes in sleep patterns are often characterized by
extreme fatigue during the day and extreme agitation at night.
Generally it is 6-12 months (or even years) after the infection
before the neurological symptoms start to become apparent in
the case of T. gambiense.
Neurological manifestations can occur within weeks after T.
rhodesiense infections.

50. African Trypanosomiasis: Disease Course

51. African Trypanosomiasis
Diagnosis:
Presumptive:
Travel history
Sign and symptomes
Confirmed :
Samples (blood, lymph nodes, bone marrow, CSF) – Trypanosomes
during febrile episodes

52. African Trypanosomiasis
Diagnosis:
Confirmed :
Methods:
1.Ordinary
Thin/thick (stained)
Wet (motility)
2.Concentration (centrifugation)
Buffy coat smear (blood)
Mini – anion exchange chromatography
Rat inoculation

53. African Trypanosomiasis
Prevention: Lies on the control, management and avoidance of
insect vector
Protective clothing (e.g. thick khaki) - Glossina attracted to
bright and dark colors
Clearing vegetation (Habitat alteration)
Wide use of insecticides
Insect repellants
Surveillance and treatment

54. African Trypanosomiasis
Treatment:
Distinguish the late encephalitic stage of the disease from the
early stage
Criteria for CNS involvement include detection of parasites in the
CSF or elevated white blood cells in the CSF.
Poor prognosis once CNS involved:
All drugs have some degree of toxicity
Generally, the least toxic drug is chosen for the primary
treatment unless evidence exists for the CNS invasion

55. African Trypanosomiasis
Treatment:
Without CNS involvement
Suramin (more toxic than pentamidine; for early
hemolymphatic stage only - not for late stage; can be given for
pregnant)
Pentamidine (less toxic, for early hemolymphatic stage only -
not for late stage; not for pregnants)
CNS involvement
Melarsoprol (most toxic; for treatment of later stages – passes
blood brain barrier)

56. African Trypanosomiasis
Drug Use Drawbacks
PentamidineEffective against early-stage
gambiense disease
•Adverse side effects
•Non-oral route
SuraminEffective against early-stage
gambiense and rhodesiense
disease
•Adverse side effects
•Non-oral route
MelarsoprolFirst line drug for late-stage
gambiense and rhodesiense
disease involving CNS
•Adverse side effects, especially
encephalopathy
•Fatal in 1-5% of cases
•Parasite resistance
•Non-oral route
EflornithineEffective against late-stage
gambiense disease involving CNS
•High cost
•Not effective against T. rhodesiense
•Non-oral route - has to be given IV
(needs hospitalization for 14 days)

57. American Trypanosomiasis
Also called Chagas disease
Agent: T. cruzi (after Oswaldo Cruz - Mentor of Carlos Chagas)
Distribution: patchy in South and Central America
Chagas' Disease
16-18 million infected
100 million at risk
50,000 deaths annually
leading cause of cardiac disease in South and Central America

58. American Trypanosomiasis

59. American Trypanosomiasis
Life Cycle:
Transmission:
Triatomine subfamily (generas: Triatoma, Rhodnius, Panstrongylus)
Different names including: triatomine bugs, reduvid bugs, kissing
bugs, and assassin bugs

60. American Trypanosomiasis
Life Cycle:
Nocturnal triatomine bug defecates (MT)
MT gets acess
Bite wound (rubbing)
Mucosa penetration
Eye contact
Invade tissues (spleen, lymph node, muscle)
Transform to Amastigote
Amastigote replicate (binary fission) in these cells
Amastigote filled cells = Pseudocysts
Amastigote differentiate to Trypomastigote
Released from cells
1.Trypomastigote invade other cells (then transform back to
Amastigote & replicate…) OR
2.Trypomastigote enter circulation

61. American Trypanosomiasis
Life Cycle:
Trypomastigote in circulation
Taken by bug (Trypomastigote to Epimastigote in mid gut
Epimastigote replicate by binary fission & attach to
epithelium in rectal gland
E to T
T to MT (infective stage)
MT gets in to lumen (to be defecated)

62. American Trypanosomiasis

63. American Trypanosomiasis
Clinical features:
The disease exhibits three phases:
acute, indeterminate (or latent), and
chronic.
1.Acute phase
Active infection
1-4 months
Majority asymptomatic
Romanas’ sign

64. American Trypanosomiasis
Clinical features:
2.Indeterminate phase
10-30 years of latency
No detectable parasitemia
Relatively asymptomatic
Sero-positive

65. American Trypanosomiasis
Clinical features:
3.Chronic phase
10-30% of infected persons
Myocarditis, cardiomyopathy
Congestive heart failure
Megasyndromes (Megacolon,
Megaoesophagus)
•Victim may not be able to swallow
and dies from starvation
•Feces not formed effectively and victim
Paucity of parasites
Megacolon

66. American Trypanosomiasis
Diagnosis:
1.Clinical:
History of living in infested
house
Bug bite, chagoma, Romana's
sign
Cardiac or gastro- intestinal
symptoms

67. American Trypanosomiasis
Diagnosis:
2.Parasite detection (acute):
Direct blood exam
Stained blood smears
Inoculation into mice
In vitro culture
Xenodiagnosis
Is used to diagnose cases in which there are too few
trypomastigotes in bloodstream.
Procedure involves feeding an uninfected lab-reared reduviid bug
on a patient; bug is examined for epimastigotes in a 10-30 days.
PCR

68. American Trypanosomiasis
Control:
Improvement of human dwellings
Health education
Separation of animal stalls from house
Insecticides
Gentian violet in blood for transfusions

69. American Trypanosomiasis
Treatment:
Acute stage 
Nifurtimox (8-16 mg/kg/day, 60-90 days)
Benznidazole (5-7 mg/kg/day, 30-120 days)
Chronic stage 
Treat symptoms