MIDTERM LEC: Trypanosoma Flashcards
● Located in the BLOOD AND TISSUE of humans
and other vertebrate hosts, and in the GUT of
insect vectors
● Digenetic and involves complex, pleomorphic
life cycles
● Transmission: via bite of an arthropod vector
● Main reservoir: humans
● Intermediate host: arthropod vector
HEMOFLAGELLATES
HEMOFLAGELLATES Two genera:
- Trypanosoma
- Leishmania
Vectors of hemoflagellates found in PH
○ T. cruzi:
Triatoma and Rhodnius bugs
Vectors of hemoflagellates found in PH
Leishmania spp:
Phlebotomus spp
MORPHOLOGICAL STAGES OF HEMOFLAGELLATES:
- A specialized region of the mitochondria consisting of a network of circular DNA (kDNA) that contains
many copies of the mitochondrial genome
- Crucial for replication and segregation of kDNA circles
- Consist of a deeply staining PARABASAL BODY and adjacent dotlike BLEPHAROPLAST
KINETOPLAST
MORPHOLOGICAL STAGES OF HEMOFLAGELLATES:
- Portion that is inside the body of the parasite and extends from blepharoplast to surface of the body
AXONEME
- FREE FLAGELLUM at the anterior end that traverses on the surface
- A SINUS EXTENSION of the cytoplasmic membrane which helps in movement by performing a vigorous, wavelike, reversible movements
UNDULATING MEMBRANE
Thin, hairlike structure which originates from the blepharoplast
FLAGELLUM
DEVELOPMENTAL STAGES
- Roundish-oval
- Size: 5 by 3 um
- Nucleus: large single, off-center
- No external flagellum
- ROUTINELY FOUND IN HUMANS
- Found primarily in tissues, as well as CNS
within macrophages, where they multiply
- Found intracellularly in vertebrate hosts of
T. cruzi and Leishmania spp.
AMASTIGOTE STAGE
- Long and slender
- Size: 9-15 um
- Nucleus: one, located in or near center
- Kinetoplast: anterior to nucleus; at anterior
end of cell - NO UNDULATING MEMBRANE
- INFECTIVE STAGE of Leishmania in the midgut
and proboscis of the insect vector - May only be seen if blood sample is collected
immediately after transmission to individual
PROMASTIGOTE STAGE
- Long and slightly wider than promastigote form
- Size: 9-15 um
- Nucleus: one, located in posterior end
- Kinetoplast: close to the nucleus than
promasitgote - Flagellum: runs alongside the body as a
short undulating membrane - T. gambiense and T. rhodesiense occur:
salivary glands of the vector tsetse fly - T. cruzi: midgut of the vector reduviid bug
- NOTE: ALL SPECIES OF Trypanosoma
that infects humans assume an epimastigote
stage in the insect vector or in culture
EPIMASTIGOTE
- Long, slender
- Size: 12-35 um long by 2-4 um wide
- Assume the shape of the letters C, S, or U in
stained blood films - Nucleus: single large, anterior to kinetoplast
- Routinely found in human specimens along
with the amastigote stage - Flagellum: runs alongside the entire long of
the cell forming a long undulating membrane - Infective stage of Trypanosoma found in
the arthropod vector - Stage found in the blood of the infected
invertebrate
TRYPOMASTIGOTE
From the Greek words trypano (borer) and
soma (body)
● Causes Chagas disease and Human
African Trypanosomiasis
● MOT: bites of infected Tsetse flies
● Definitive host: mammals
● Intermediate host: arthropod vector
● Known to invade the CNS, blood and tissues
causing acute and chronic protozoal diseases
Trypanosoma spp.
Chagas disease or American trypanosomiasis is cause by?
Trypanosoma cruzi (trypanosome group Stercoraria)
Carlos Chagas - found that the trypanosomes he dissected from the intestine of a triatomid bug were the same parasites found in the blood of a child suffering from fever and enlargement of the lymph nodes.
Human African Trypanosomiasis (HAT) is caused by?
Trypanosoma rhodisiense
morphological stages of Trypanosoma spp.
Amastigotes, promastigotes, epimastigotes, and
trypomastigotes
Two modes of development in the vector of Trypanosoma spp.
salivaria & stercoraria
trypanosomes migrate to the MOUTH PARTS of the vector so that the infection is transmitted via their
bite (inoculative transmission)
Salivaria
trypanosomes migrate to the HINDGUT and are passed in the feces. Acquired by rubbing the feces
of the vector into the wound caused by its bite
Stercoraria
● Etiologic agent of Chagas Disease or
American trypanosomiasis
● Only parasite that was discovered and
studied before it was known to cause a
disease
● Belongs to the trypanosome group
Stercoraria
Trypanosoma cruzi
Trypanosoma cruzi become a Major Food-borne Disease in _____________ (due orally acquired
ACD (Acute Chagas Disease) in Acre
(Forest Community of Seringal
Miraflores–Affecting 13 individuals who
shared pulp of Acai Berries
Brazilian Amazona
LESS COMMON ROUTES FOR THE
TRANSMISSION OF T. CRUZI:
● Blood Transfusion
● Organ transplantation
● Transplacental transmission
● Foodborne transmission
● AKA Trypanosoma Herpetosoma due to its subgenus that is transferred by Reduviid Bug
● Was first found as, Trypanosoma cruzi
● Common Associated Disease and Condition:
NOT KNOWN
● Infections are generally ASYMPTOMATIC
and DOES NOT TEND TO SHOW NO
PATHOLOGIC CHANGES or SIGN OF
DISEASES
Trypanosoma rangeli
T. cruzi and T. rangeli are found regions of SOUTH and CENTRAL AMERICA RARE in NORTH AMERICA) particularly:
● Brazil
● Venezuela
● Colombia
● Panama
● El Salvador
● Costa Rica
● Honduras
● Guatemala
Trypanosoma cruzi
● FIRST ISOLATED in
Panstrongylus megistus
Furuncle-like lesions associated with induration, central edema and regional lymphadenopathy
❖ Appears on the site of entry of parasite
Chagoma
EYELID SWELLING; may form if the parasite penetrates through the conjunctiva
Romaña’s sign
Specimen choice detection of Trypomastigotes
Giemsa-stain blood slides
reveal amastigotes
Lymph Node Biopsy Giemsa-stained Slides & Blood Culture
seen in the peripheral blood smear throughout the course of the illness.
Trypomastigotes
- Cause TRYPANOSOMIASIS (general term
used to refer to human disease caused by
hemoflagellates of genus trypanosoma)
Trypanosoma brucei COMPLEX
Scottish pathologist; identified Trypanosoma brucei as the CA of the trypanosomal diseases known as nagana (a form of the disease often found in cattle)
and sleeping sickness
David Bruce (1895
Described Trypanosoma brucei rhodesiense
Stephens and Fantham (1910)
3 SUBSPECIES/ Trypanosoma brucei COMPLEX:
● Trypanosoma brucei gambiense
● Trypanosoma brucei rhodesiense
● Trypanosoma brucei bruceI
● Blood, Lymph, tissue space and various
organs (brain and spinal cord) and CNS
● POLYMORPHIC
○ Short stumpy forms
○ Typical slender forms
● SHAPE: Flattened, fusiform
○ Often assumes the S shape in stained blood films
● Body tapers anteriorly, blunt posteriorly
● LENGTH: 14 to 33 µm(Belizario) OR 12-35 um (Zeibig)
● WIDTH: 1.5 to 3.5 µm / 2-4 um
● NUCLEUS: CENTRAL
● KARYOSOME: Large, Centra
TRYPOMASTIGOTE
Responsible for the chronic type of sleeping
sickness in Central and WEST Africa.
○ Cause 95% of all HAT cases.
○ Sleeping sickness Manifest months or
years after initial infection.
Trypanosoma brucei gambiense
- Responsible for a more acute and rapidly
fatal form of HAT in EAST and Southern Africa.
● Cause 5% of all HAT cases.
● Symptoms may appear just weeks after infection.
Trypanosoma brucei rhodesiense
● DOES NOT INFECT HUMANS
● Causes “NAGANA” In domestic and wild
animals
Trypanosoma brucei brucei
caused by Trypanosoma brucei rhodiense
- Manifest few weeks after the exposure to the vector.
Acute HAT
caused by Trypanosoma brucei gambiense
- Manifest months or years after the
exposure to the vector.
Chronic HAT
Local, painful, pruritic, erythematous chancre located at the bite site progressing into eschar that
spontaneously resolves within 2-3 weeks.
● First sign that can be detected.
Trypanosomal Chancre (Initial Lesion)
enlarged, nontender, rubbery posterior
CERVICAL LYMPHADENOPATHY
WINTER BOTTOM SIGN (T. bruceigambiense
- may manifest as a deep, delayed HYPERESTHESIA after a slight blow on a bony projection of the body.
● In later stages, alterations in circadian rhythm
leading to daytime somnolence manifests,
followed by coma then death.
● Affected areas: frontal lobes, pons,
medulla, perivascular areas.
Kerandel’s Sign (T. brucei rhodisiense
The ability of the trypomastigote to CONTINUOUSLY CHANGE ITS SURFACE COAT, composed of variant surface glycoproteins, so that the host’s antibodies cannot recognize the parasite.
antigenic variation.
TREATMENT FOR FIRST STAGE
- IV suramin sodium
- Intramuscular pentamidine
TREATMENT FOR LATE STAGE
- IV melarsoprol
- Usually co-administered with corticosteroids
- Nitrofurazone
- Nitrofurazone + Eflornithine
First documented cases of sleeping sickness
Africa (1734)
● DOES NOT INFECT HUMANS
● Causes “NAGANA” In domestic and wild
animals.
Trypanosoma brucei brucei
Trypanosoma brucei brucei INFECT:
● Deer
● Cow
● Horse
