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BLOOD AND TISSUE
PROTOZOANS
Dr. Julius R. Migrio, Jr.
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Outline
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Prevention and
Control
What now?
Leishmaniasis
OVERVIEW
Leishmania parasites are named after W.B.
Leishman.
He recognized one of the earliest strains in
1901.
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What now?
Leishmaniasis
DEMOGRAPHICS
Affects more than 12 million people!
At risk: more than 350 million people
2 million new cases annually
1.5 million visceral leishmaniasis
500,000 cutaneous leishmaniasis
59,000 people die annually
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What now?
Leishmaniasis
DEMOGRAPHICS
Endemic in 88 countries on 4 continents
72 are developing countries
13 of which are among the least
developed
Usually targets migrants, seasonal
workers, refugees, sex workers and
truck drivers
Individual risk factors such as
malnutrition and immunosuppression
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What now?
Leishmaniasis
DEMOGRAPHICS
Endemic in 88 countries on 4 continents
Usual targets are IV drug users
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Treatment
Prevention and
Control
What now?
Leishmaniasis
DEMOGRAPHICS
Endemic in 88 countries on 4 continents
Cutaneous leishmaniasis cases:
Iran
Afghanistan
Syria
Saudi Arabia
Brazil
Peru
Visceral leishmaniasis cases:
Bangladesh
Brazil
India
Nepal
Sudan
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What now?
Leishmaniasis
CAUSATIVE AGENT
Parasitic protozoa of the genus Leishmania
Over 20 species and subspecies infect
humans
Eg. Leishmania donovani, L. major, L.
braziliense
PHOTO: Photomicrograph of Leishmania in a blood film (using
Romanovski stain).
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What now?
Leishmaniasis
LIFE CYCLE
Transmitted mainly by bites from sandflies
Genus Phlebotomus
About 30 species are known vectors
Reservoir:
Dogs
Rats
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What now?
Leishmaniasis
LIFE CYCLE
Promastigotes enter the bloodstream
then are ingested by macrophages
then mature to amastigotes
then reproduce by binary fission
then burst out from the macrophage
and either infect other macrophages
or get ingested by sandflies
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What now?
Leishmaniasis
SYMPTOMS
The leishmaniases can be classified into 4
main forms:
1. Visceral leishmaniasis (VL)
2. Cutaneous leishmaniasis (CL)
3. Mucocutaneous leishmaniasis (MCL)
4. Diffuse cutaneous leishmaniasis (DCL)
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What now?
Leishmaniasis
SYMPTOMS
1. Visceral leishmaniasis (VL)
- Kala azar
- Most serious form
- Caused by L. donovani
- Mortality rate approaches 100%!
Symptoms:
- Irregular bouts of fever
- Weight loss
- Hepatomegaly
- Splenomegaly
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Leishmaniasis
SYMPTOMS
2. Cutaneous leishmaniasis (CL)
- Baghdad ulcer, Delhi boil, Bouton dOrient
- The most common form
- Caused by L. major
- Usually in Africa or Asia
Symptoms:
- Up to 200 simple skin lesions
- Wounds heal within a few months
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Leishmaniasis
SYMPTOMS
3. Mucocutaneous leishmaniasis (MCL)
- Caused by L. braziliensis
Symptoms:
- Starts as skin ulcers
- Spreads, causing dreadful and massive
tissue destruction, especially of the
nose and mouth
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What now?
Leishmaniasis
SYMPTOMS
4. Diffuse cutaneous leishmaniasis (DCL)
- Disseminated and chronic skin lesions
- resembles leprotamous leprosy
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What now?
Leishmaniasis
DIAGNOSIS
1. Direct visualization
2. Freeze-dried Direct Agglutination Test
(DAT)
3. rK39 dipstick
4. Latex Agglutination urine test
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Treatment
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Control
What now?
Leishmaniasis
DIAGNOSIS
1. Direct visualization
- Uses tissue aspirate
- Spleen
- Bone marrow
- Lymph nodes
- Unsuitable for field use
- Invasive
- Low sensitivity
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What now?
Leishmaniasis
DIAGNOSIS
2. Freeze-dried Direct Agglutination Test
(DAT)
-Detects antibodies
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Control
What now?
Leishmaniasis
DIAGNOSIS
3. rK39 dipstick
-Based on recombinant antigen of
leishmania parasite
-Being investigated for use in active case
detection
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What now?
Leishmaniasis
DIAGNOSIS
4. Latex Agglutination Urine Test
-Detects antigens
-Used among patients who have
compromised immune response
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What now?
Leishmaniasis
TREATMENT
Most cases of cutaneous leishmaniasis
heal without treatment
Immunity against further infection can be
attained
immunization efforts in South-west Africa
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What now?
Leishmaniasis
TREATMENT
Other forms of leishmaniasis require long
courses:
pentavalent antimony drugs
Given parenterally
Meglumine antimonate
Sodium antimony gluconate
Resistance have been reported, prompting
the use of amphotericin B
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What now?
Leishmaniasis
TREATMENT
Miltefosine
- First oral treatment for VL
- Potential teratogen
- Possibility of developing resistance
Paromomycin
- An aminoglycoside
- Used topically for CL
- Used orally as 2nd line treatment of VL
- Injectable formulation is being
developed
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What now?
Leishmaniasis
PREVENTION & CONTROL
Vector control
Insect repellants
Insecticides
Bednets
Reservoir control
Poisoned baits
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What now?
AFRICAN TRYPANOSOMIASIS
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What now?
African Trypanosomiasis
DEMOGRAPHICS
60 million people are at risk
300,000 500,000 new cases annually
66,000 people die annually
Prevalence of more than 70% in some
areas
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What now?
African Trypanosomiasis
DEMOGRAPHICS
36 countries in sub-Saharan Africa: 7 countries: disease is
highly endemic
4 countries: disease is endemic
2 countries: disease has moderate endemicity
3 countries: status is poorly understood
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What now?
African Trypanosomiasis
CAUSATIVE AGENTS
Protozoan parasites of the genus
Trypanosoma
- Trypanosoma brucei rhodesiense
- east and southern Africa
- T.b. gambiense
- west and central Africa
- T.b. brucei
- cattle disease only
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LIFE CYCLE
Transmitted mainly by bites from tsetse flies
Genus Glossina spp.
Parasites mature in the salivary glands
Reservoir:
cattle
wild animals
African Trypanosomiasis
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LIFE CYCLE
Metacyclic trypomastigotes enter the
bloodstream
then transform into bloodstream
trypomastigotes
then reproduce by binary fission
and get ingested by flies
African Trypanosomiasis
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SYMPTOMS
T.b. gambiense
- Chronic infection
- less severe (several years)
T.b rhodesiense
- Usually acute infection
- more severe (days to weeks)
- Progresses to death!
African Trypanosomiasis
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SYMPTOMS
Early signs and symptoms
- fever
- headache
- malaise
- anemia
- joint pains
- enlarged lymph glands
- splenomegaly
Late signs and symptoms
- neurological symptoms
- progresses to coma
- fatal if left untreated!
African Trypanosomiasis
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SYMPTOMS
Pathophysiology: African Sleeping Sickness
Mainly an immune-mediated
hypersensitivity reaction
Due to parasite antigens
acting on:
o RBCs
o cardiac tissue
o brain tissue
African Trypanosomiasis
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What now?
DIAGNOSIS
1. Direct visualization
2. Card Agglutination Test for Trypanosomes
(CATT)
African Trypanosomiasis
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What now?
DIAGNOSIS
1. Direct visualization
- Can do blood smear or lumbar puncture
- Invasive
- Not suitable in the field
African Trypanosomiasis
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What now?
DIAGNOSIS
2. Card Agglutination Test for Trypanosomes
(CATT)
- useful for screening of T. b. gambiense
- no comparable test for T. b. rhodesiense
African Trypanosomiasis
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What now?
TREATMENT
Pentamidine
for early-stage T. b. gambiense sleeping
sickness
Suramin
for early-stage T. b. rhodesiense
sleeping sickness
African Trypanosomiasis
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What now?
TREATMENT
Melarsoprol
for late-stage disease of both forms of
sleeping sickness
Original drug of choice
Relatively toxic!
Growing resistance patterns
African Trypanosomiasis
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What now?
TREATMENT
Eflornithine
current 1st line drug for T. b. gambiense
sleeping sickness patients who do not respond to melarsoprol
Resurrection drug
costs $US 300-500 per patient and has
many side-effects
Current studies (June 2009) show
Nifurtimox-Eflornithine combination
safer and as effective
African Trypanosomiasis
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What now?
PREVENTION & CONTROL
Surveillance of at-risk populations
Clearance of tsetse fly breeding
grounds
Insecticides
Fly traps and screens
African Trypanosomiasis
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What now?
CHAGAS DISEASE
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What now?
Chagas Disease
OVERVIEW
named after a Brazilian doctor, Carlos
Chagas
first described in 1909
- Illustrated the life-cycle of the parasite
- identified the insect vector
- identified small mammals as reservoir
hosts
- suggested means to help prevent
transmission
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What now?
DEMOGRAPHICS
About 16-18 million people are infected
- 25% are symptomatic
- About 2-3 million chronic cases
More than 200,000 new cases annually
More than 20,000 annual deaths
About 350 million people are at risk
Chagas Disease
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What now?
DEMOGRAPHICS
18 countries in 2 ecological zones:
1. Central America, Mexico, Northern South
America
2. Southern Cone of South America
Chagas Disease
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CAUSATIVE AGENTS
Protozoan parasites Trypanosoma cruzi
Chagas Disease
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LIFE CYCLE
Transmitted to humans in 3 ways:
1. By bloodfeeding Assassin/Reduviid
bugs (sub-family Triatominae)
2. Through transfusion with infected blood
3. Congenitally, from infected mother to
fetus
Chagas Disease
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What now?
LIFE CYCLE
Heres how it goes
Bug bites you while it sucks blood
It poops while feeding on your blood
Feces contains
metacyclic trypomastigotes
Trypomastigotes enter through bite wound
or mucosal surfaces
Chagas Disease
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LIFE CYCLE
Heres how it goes
They invade cells
where they develop into amastigotes
and replicate by binary fission
and burst out as bloodstream
trypomastigotes
and can:
Invade other cells
Be sucked by another bug
Chagas Disease
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SYMPTOMS
Usually, an initial small furunculoid lesion at
the bite site
Within a few days, fever and
lymphadenopathy develops
In children and immunocompromised
patients, may lead to dissemination and
death
Chagas Disease
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SYMPTOMS
Romaas sign
- swollen palpebrae
- due to conjunctival point of entry
- painless
- persists for up to 2 months
Chagas Disease
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SYMPTOMS
May proceed to an asymptomatic phase
- Could last from months to years
- Dissemination of the parasites:
1. Heart
2. GI tract (intestines and esophagus)
3. Brain (?)
Chagas Disease
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SYMPTOMS
PATHOPHYSIOLOGY:
Theory 1:
Infection-induced autoimmune disease
parasite mediated cross-reaction
Supported by paradigm of
chronic disease fewer parasites!
Theory 2:
Parasite persistence
chronic infection leads to chronic
inflammation
Chagas Disease
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What now?
DIAGNOSIS
1. Direct visualization
2. Indirect test
3. Imaging tests
Chagas Disease
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What now?
DIAGNOSIS
1. Direct visualization
- Blood smear
- observation of rapid movements of live
trypomastigotes
Chagas Disease
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What now?
DIAGNOSIS
2. Indirect test
-Immunologic tests (ELISA, IFA)
-Hemoculture in liver infusion tryptose
medium
-Xenodiagnosis
- Uses live Triatomina bugs
- Allowed to feed on a patient
- Bug intestinal contents are then
examined
Chagas Disease
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What now?
DIAGNOSIS
2. Imaging tests
-Abdominal x-ray
-Chest x-ray
-Esophageal imaging
-Electrocardiogram
- low-voltage QRS complexes (acute
phase)
- Ventricular premature beats, BBB, T-
wave inversion, low-voltage QRS,
etc. (chronic phase)
Chagas Disease
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What now?
TREATMENT
Nifurtimox and Benznidazole
- Nitroimidazole
- Used in acute and early chronic (a few
years) phase
- No effect on chronic cases
- Side effects: hypersensitivity,
polyneuritis, neutropenia
- Category C in pregnancy
Chagas Disease
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What now?
TREATMENT
Cardiopathy
- Class III antiarrythmics (Amiodarone,
Sotalol)
- Diuretics (if with CHF)
- Pacemakers for persistent
bradyarrythmias
- Heart transplant!
Chagas Disease
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What now?
TREATMENT
Megaesophagus
- Balloon dilatation (but with risk of
rupture)
- Surgical treatment of achalasia
- Bowel loop interposition for late stages
Megacolon
- Laxatives for constipation
- Surgery: end-to-end anastomosis
Chagas Disease
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What now?
PREVENTION & CONTROL
Chagas Disease
Vector Control
- Insecticides
- substituting plastered walls and a metal
roof for adobe-walled, thatch-roofed
dwellings
- Sanitation
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What now?
PREVENTION & CONTROL
Chagas Disease
Transfusional Control
- Blood transfusion transmission is the
second main route of T. cruzi infection
- Infection rates can go up as high as
24%
- Infectivity risk: 20% for T. cruzi
- Screening should be mandatory!
