14 Blood Flagellates Flashcards
Causative agent of leishmaniasis
Leishmania donovani (most important)
L major
L brasiliensis
Small, dark teardrop-shaped
Motile due to presence of flagella
Leishmania amastigotes
Vector of leishmaniasis
Sandfly
Sandfly
Endemic in old-world countries (Europe, Asian and African countries)
Plebotomus
Sandfly
Endemic in new-world countries (America)
Lutzomiya
Primary reservoir hosts of Leishmania
Dogs (L. infantum)
Humans (L. donovani, L.tropica)
Modes of transmission of Leishmania
Blood-borne: Blood transfusion Wound contamination Exposure to contaminated samples Vertical transmission
Infective stage of Leishmania
Promastigotes
What ingests the promastigotes as they enter the bloodstream
Macrophage
Promastigotes in the macrophages will become ____, which will reproduce via binary fission
Mastigotes
Also known as Baghdad ulcer, Delhi boil, Bouton d’ Orient
Least severe form of leishmaniasis
Symptoms include craters and erosions
Cutaneous leishmaniasis (CL)
Most common species that cause CL
L. major
Others include L. tropica, L. infantum
Mostly seen in South America
Caused by L. braziliensis
Mucocutaneous leishmaniasis (MCL)
Skin ulcers in MCL
Chiclero ulcers
AKA Parrot’s beak or Camel nose
Massive tissue destruction of the mucus membranes of the mouth and nose
Espundia
Morbidity is higher compared to MCL and CL
Affects big area of the body, but can also be found in localized areas of the skin
Resembles lepromatous leprosy
Diffuse cutaneous leishmaniasis (DCL)
What causes DCL
L. aethiopica
L. mexicana
Symptoms of DCL
Disseminated and chronic skin lesions
Most serious form of leishmaniasis
Has more than 95% mortality
Affects visceral organs
Visceral Leishmaniasis (VL)
Etiologic agents of VL
L. donovani
L. chagasi
Double quotidian fever
Weight loss
Prominent hepatomegaly, splenomegaly
Anemia, leukopenia, thrombocytopenia
VL
Kala azar
Diagnosing leishmaniasis
Direct visualization Freeze-dried direct agglutination test rK39 Dipstick Latex agglutination urine test Leishmanin (Montenegro) skin test
Primary confirmatory diagnosis
Gold standard for confirming leishmaniasis
Direct visualization
Direct visualization uses tissue aspirate from:
Spleen
Bone marrow
Lymph nodes
Direct visualization is unsuitable for filed use because:
Invasive
Low sensitivity
Detects antibodies
Rapid diagnostic test, hence, used in field
Freeze-dried direct agglutination test (DAT)
Based on recombinant antigen of Leishmania parasite
Being investigated for use in active case detection
rK39 Dipstick
Detects Leishmania antigens
Used among patients who have a compromised immune response
Latex agglutination urine test
Rapid diagnostic test used to detect exposure
Used for CL and MCL
Similar to an allergy test (PPD), wherein you inject an antigen and wait for delayed hypersensitvity region
Leismanin (Montenegro) skin test
Immunity against further infection can be attained
Leishmanization
Three methods of leishmanization
Intentional biting
Pus inoculation
Cultured promastigotes
Natural immunization
Intentional biting
Gets pus draining form lesion and inoculate into another person
if person is healthy enough, he will develop antibodies
Pus inoculation
Live attenuated vaccination
Cultured promastigotes
Treatment for leishmaniasis
Antimonate-containing drugs (Pentavalent antimony drugs):
Meglumine antimonite
Sodium antimony gluconate
Prevention and control methods of leishmaniasis
Vector control (insect repellants, insecticides, kulambo) Reservoir control (poisoned baits)
Opportunistic AIDS infection
Leishmaniasis
New drug for treating leishmaniasis
Sitamaquine
Oral aminoquinolone
Also known as Human African Trypanosomiasis or African sleeping sickness
African trypanosoma
Majority of the cases of African trypanosoma come from ____
Sub-Saharan Africa
Causative agents of African trypanosoma
Trypanosoma brucei rhodesiense
T. brucei gambiense
T. brucei brucei
East and Southern Africa
2% of cases
Faster killer but less prevalent (more fatal because there are less cases)
T. brucei rhodiense
West and Central Africa
Has the most number of cases (98%)
Slower killer than T. b. rhodesiense
T. b. gambiense
Cattle disease only
T. b. brucei
Vector of African trypanosoma
Tse-tse fly (Glossina spp)
Reservoir hosts of African trypanosoma
Dogs, pigs, cattle, wild animals
Infective stage of T. b. rhodiense
Metacyclic trypomastigotes
When tsetse flies are infected via blood ingestion, trypomastigotes become ____ in the gut
Procyclic trypomastigotes
Phases of African trypanosoma
Initial
Early
Late
Chancre formation (Dermolytic lesion)
Pruritic lesion
Lasts for 2-3 weeks
Initial Phase
A local, hard, painful lesion at the site of inoculation
Chancre
Heals by itself
A piece of dead tissue that is cast off from the surface of the skin
Eschar
Parasitic proliferation
Systemic
Lasts 1-6 months
S/s include relapsing fever, headache, malaise, anemia, joint and muscle pains, Winterbottom sign
Early phase (hemolymphatic phase)
Enlarged posterior cervical lymph nodes
Winterbottom sign
Morbidity of the disease is seen
Involvement of the CNS
S/s include apathy, behavioral changes, headaches, sleep pattern changes, convulsions, speech defects, splenomegaly, Kerandel’s sign, paralysis, progress to coma
Late phase (Meningoencephalitic phase)
Deep, delayed, bilateral hyperesthesia
Exaggerated response to any stimuli, particularly pain
Kerandel’s sign
Mainly an immune-mediated hypersensitivity reaction due to parasite antigens acting on RBC, cardiac tissue and brain tissue
African trypanosoma
Diagnosis of African trypanosom
Direct visualization
Card agglutination test for trypanosome
Gold standard
Visualizes highly motile trypomastigotes
Mainly used in the early phase
Invasive
Direct visualization
Useful for screening fo T.b. gambiense
No comparable test for T. b. rhodesiense
Rapid and specific
Useful in the field setting
Card agglutination test for trypanosome (CATT)
For early stage of T. b. gambiense infection
Pentamide
For early stage of T. b. rhodiense infection
Suramin
First line drug for late-stage disease of both forms of sleeping sickness
Removed due to toxicity and growing resistance
Melarsoprol
Current first line drug for T. b. gambiense sleeping sickness patients who do not respond to melarsoprol
Ressurection drug
Eflornithine
Chagas disease
Majority of the cases come from Mexico, Central America and South America
South American Trypanosoma
Causative agent of Chagas disease
Has flagella
Trypanosoma cruzi
Zoonotic disease that can be transmitted to humans by blood-sucking triatomine bugs
Chagas disease
Infection of Chagas disease is most commonly acquried thorugh contact with ____ of an infected insect
Feces
Common triatomine vector species for Chagas disease belong to genera:
Triatoma
Rhodnius
Panstrongylus
Main vector for South American trypanosoma
Triatomine/Reduviid/Assassin bug
Triatomine bug releases infective ______ in its feces near the site of bite wound
Metacyclic trypomastigotes
Metacyclic trypomastigoes enter host’s mucosal membranes and differentiate into ______
Intracellular amastigotes
Trypanosome amastigotes multiply by binary fission and differentiate into ____. which burst out and are released into bloodstream
Mature trypomastigotes
If the trypomastigotes are ingested by the triatomine bug, these transform into ____ in the vector’s midgut
Epimastigotes
Diagnostic stage of T. cruzi
Amastigotes
Initial small furunculoid lesion at the bite site
Chagoma
Swollen palpebrae Due to conjunctival point of entry Painless but may be itchy on intial bite Persist up to 2 months Bugs bite at mucosal areas due to moisture present
Romana sign
Acute phase of Chagas disease include these s/s:
Chagoma
Fever and lymphadenopathy
Romana sign
Problematic phase, in which parasites are already proliferating inside the patients
Could last from months to years
Marked by fibrotic reactions
Indeterminate chronic phase
Diagnostic methods for Chagas disease
Direct visualization
Indirect test
Imaging test
Gold standard
Involves observation of rapid movement of live trypomastigotes
Only useful during first 2 months
Direct visualization
Immunologic tests
Hemoculture in liver infusion tryptose medium
Xenodiagnosis (use of live Triatomina bugs)
Indirect test
Treatment for Chagas disease
Inhibits unique enzyme trypanothione reductase
Nifurtimox
Benznidazole
Treatment for cardiopathy caused by Chagas disease
Allopurinol, itraconazole
Heart transplants
Preventive and control methods against Chagas disease
Vector control
Transfusional control