M19 - Trypanosomes and Leishmania

*Lumenal*
– Trichomonas vaginalis
– Giardia lamblia
*Hemoflagellates*
– Trypanosoma brucei
– Trypanosoma cruzi
– Leishmania spp.
Flagellates: Categories
Trypanosomatids or Kinetoplastida (Definition)
group of protozoan pathogens that include Leishmania and Trypanosomes
A group of single-cell flagellate protozoa, including a number of parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments.
– Major distinguishing feature is the presence of a *kinetoplast*
Trypanosomatids or Kinetoplastida (Definition)
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Kinetoplast
characteristic modified mitochondrion
Network of circular DNA (kDNA) inside a large mitochondrion that contains many copies of the mitochondrial genome. Usually adjacent to the organism’s flagellar basal body, suggesting that it is tightly bound to the cytoskeleton. Only found in protozoa of the class Kinetoplastida.
– In trypanosomes, kinetoplast exists as a dense granule of DNA within the large mitochondrion
Kinetoplast
Undulating Membrane
external flagellum attached to the cell body
– a lateral expansion of the plasma membrane in some flagellates that is usually associated with a flagellum
Undulating Membrane
Various morphologic forms of trypanosomatids
Trypomastigote, amastigote, epimastigote, promastigote
Trypomastigote
An *extracellular “non-replicative” form of a parasite*. It is a leaf-like form with undulating membrane and flagellum that emerges through a flagellar pocket and runs the whole length of the cell. A large kinetoplast is found at the base of the flagellum; i.e., posterior end of the cell. Trypomastigote is *found in the bloodstream* of infected vertebrate host.
Trypomastigote
Amastigote
An *intracellular “replicative” form* of a parasite. It is a round/oval shaped cell without any protruding flagellum. Amastigotes replicate inside the infected tissue cells (of vertebrate host) by *binary fission* and *transform into trypomastigotes*
Amastigote
Epimastigote
A developmental stage in trypanosomes. The undulating membrane is shortened and the flagellar pocket and the kinetoplast are found anterior and adjacent to the nucleus. The flagellum emerges in the middle of the cell. Epimastigote is *found in the intestinal tract of the insect host*
This morphological form is found in Trypanosoma brucei and Trypanosoma cruzi. It is the main experimental stage in T. cruzi.
Epimastigote
One of the morphological stages in the development of Leishmania species. Promastigote is an *extracellular motile form* that *divides by longitudinal binary fisson in the sand fly*. They are characterized by a free anterior flagellum and the kinetoplast at the anterior end of the body.
– *Procyclic or Metacyclic form*
Promastigote
Either dividing form of Trypanosoma brucei found in the tsetse fly midgut, or non-infective promastigote stage of Leishmania species, found in the sand fly vector.
Promastigote Procyclic Form
*Infectious insect stage* of Leishmania species and Trypanosoma cruzi
(Promastigote in the Proboscus?)
Promastigote Metacyclic Form
Trypomastigote Species
Trypanosoma cruzi & T. brucei *mammalian forms*
T. brucei “procyclic” Trypomastigote insect form
Trypomastigote Species
Epimastigote Species
T. cruzi and T. brucei *insect form*
Epimastigote Species
Promastigote Species
Leishmania insect forms
Promastigote Species
Amastigote Species
Leishmania and T. cruzi intracellular replicative form
Amastigote Species
Blood Flagellates
Kinetoplastids
– T. brucei
– T. cruzi
– Leushmania
(Your “Kin” are “of your blood”)
Blood Flagellates
“Sleeping sickness”
Human African Trypanosomiasis (HAT) Causes…
Trypanosoma brucei
– ssp. gambiense (West)
– ssp. rhodesiense (East)
HAT: Infectious Agent
HAT: Epidemiology (Trypanosoma brucei)
300-500,000 infected in Africa
– 45,000 cases reported to WHO in 1999
– 60 million at risk
– 100,000 die annually
– Wide variability between neighboring regions
– Epidemic 1920-1960… and 1970-present
– Perpetuated by civil war, displacement, health systems collapse, forest penetration
2009
– First year with < 10,000 cases reported to WHO in 50 years. - Actual case estimate: 30,000
HAT: Epidemiology (Trypanosoma brucei)
Congo
80% of all cases
5% total population +
50% some villages +
#1 mortality cause in certain provinces
Congo
Species of salivary trypanosome which causes *Human African Tyypanosomiasis* (HAT aka “Sleeping Sickness”) in humans and *Nagana* in animals.
Traditionally grouped into 3 *Subspecies*:
– T. brucei brucei (unable to infect humans except in RARE cases)
– T. brucei gambiense
– T. brucei rhodesiense
Transmission of between mammal hosts is usually by an *insect vector*, (tsetse fly).
Undergo complex morphological changes as they move between insect and mammal over course of their life cycle
Mammalian bloodstream forms notable for *variant surface glycoprotein (VSG) coats*, which undergo remarkable antigenic variation, enabling persistent evasion of host adaptive immunity and chronic infection
– *One of few pathogens that can cross the blood brain barrier*
Trypanosoma brucei
HAT: Vector
Glossina (“Tsetse fly”)
HAT: Vector
HAT: Life Cycle
*Human Stages*
1.) Tsetse fly takes a blood meal (injects *metacyclic trypomastigotes*)
2.) Injected trypomastigotes transform into *bloodstream trypomastigotes*, which are carried to other sites
3.) Trypomastigotes multiply by binary fission in various body fluids (e.g. blood, lymph, spinal fluid) EXTRACELLULAR reproduction
4.) Trypomastigotes in blood
5.) Tsetse fly takes a blood meal (bloodstream tryptomastigoes are ingested) = End of Human Stages
*Tsetse Fly Stages*
6.) Bloodstream Trypomastigotes transform into *Procyclic Trypomastigotes* intsetse fly’s midgut. Procyclic Trypomastigotes multiply by binary fission
7.) Procyclic Trypomastigotes leave the midgut and transform into*Epimastigotes*
8.) Epimastigotes multiply in salivary gland. They transform into *Metacyclic Trypomastigotes*
REPEAT
HAT: Life Cycle
From the bite, parasites first enter the lymphatic system and then pass into the bloodstream. Inside the mammalian host, they transform into bloodstream trypomastigotes, and are carried to other sites throughout the body, reach other body fluids (e.g., lymph, spinal fluid), and continue to replicate by binary fission.
*The entire life cycle of African trypanosomes is represented by extracellular stages*
HAT in your Body Fluids
HAT: Anthropo / Zoonosis
Glossina spp Tsetse Fly can transfer T. rhodesiense from wild game animals (e.g. bushbuck antelope) to people, and T. gambiense between people.
T. brucei causes Nagana in animals only.
HAT: Anthropo / Zoonosis
Trypanosomiasis: Game-Attacking Species
T. rhodesiense
– can be transmitted to humans via Tsetse fly after cyclical development
Trypanosomiasis: Game-Attacking Species
Trypanosomiasis Riverine Species
T. gambiense
– no animal resevoir
– can be transmitted between people via Tsetse fly after cyclical development
Trypanosomiasis Riverine Species
Trypanosomiasis Possible Mutation
T. brucei
– causes Nagana in animals
*Epimastigote in vector*
Trypanosomiasis Possible Mutation
West Africa: 95% of reported cases (ssp. gambiense)
East Africa: ~5% of cases (ssp. rhodesiense)
East vs West Africa: HAT Infections
HAT Clinical Presentation: *Primary Stage* (Gambiense and Rhodesiense)
*Chancre*
1.) Painless skin chancre that appears about 5-15 days after the bite, resolving spontaneously after several weeks (less commonly seen in T brucei gambiense infection)
2.) Intermittent fever (refractory to antimalarials), general malaise, myalgia, arthralgias, and headache; usually 3 weeks after the bite
3.) Generalized or regional lymphadenopathy – Posterior cervical lymphadenopathy (*Winterbottom sign*) is characteristic of T brucei gambiense African trypanosomiasis
4.) Facial edema (minority of patients)
5.) Transient urticarial, erythematous, or macular rashes 6-8 weeks after onset
6.) Trypanids (ill-defined, centrally pale, evanescent, annular, or blotchy edematous erythematous macules on the trunk)
HAT Clinical Presentation: *Primary Stage* (Gambiense and Rhodesiense)
*Winterbottom’s Sign*
Protracted fevers and sore neck
Firm, tender nodes palpated in posterior cervical chain
HAT Clinical Presentation: *Gambiense 2nd Stage*
HAT Clinical Presentation: *Gambiense 3rd Stage*
Cachexia (wasting syndrome)
Dementia
Athetosis (writhing hands/arms)
Seizures
Coma
Death
HAT Clinical Presentation: *Gambiense 3rd Stage*
Winterbottom's Sign
Seen in the early phase of African trypanosomiasis (T. b. brucei rhodesiense and T. b. gambiense).
Swelling of lymph nodes (lymphadenopathy) along the back of the neck, in the posterior cervical chain of lymph nodes, as trypanosomes travel in the lymphatic fluid and cause inflammation.
May be suggestive of cerebral infection
Winterbottom’s Sign
HAT Clinical Presentation: *Rhodesiense 2nd Stage*
Chaotic fever
Prostration
Hemolytic anemia
Multi-Organ System Failure (MOSF)
Death
HAT Clinical Presentation: *Rhodesiense 2nd Stage*
HAT Clinical Presentation: *Rhodesiense 3rd Stage*
*Rapid, severe encephalitis*
Pts may die of Multi-Sytem Organ Failure (*MOSF*) before distinct encephalitis
HAT Clinical Presentation: *Rhodesiense 3rd Stage*
Trypanosoma brucei gambiense is found in 24 countries in west and central Africa. This form currently accounts for over 98% of reported cases of sleeping sickness and causes a chronic infection. A person can be infected for months or even years without major signs or symptoms of the disease. When more evident symptoms emerge, the patient is often already in an advanced disease stage where the central nervous system is affected.
Trypanosoma brucei gambiense WHO description
Trypanosoma brucei rhodesiense is found in 13 countries eastern and southern Africa. Nowadays, this form represents under 2% of reported cases and causes an acute infection. First signs and symptoms are observed a few months or weeks after infection. The disease develops *Rapidly* and invades the CNS. Only Uganda presents both forms of the disease.
Trypanosoma brucei rhodesiense WHO description
*Progresses rapidly*. In some patients, a large sore (a chancre) will develop at the site of the tsetse bite. Most patients develop fever, headache, muscle and joint aches, and enlarged lymph nodes within 1-2 weeks of the infective bite. Some people develop a rash. After a few weeks of infection, the parasite invades the CNS and eventually causes mental deterioration and other neurologic problems. *Death ensues usually within months*.
T. b. rhodesiense infection (East African sleeping sickness) (CDC Description)
*Progresses more slowly*. At first, there may be only mild symptoms. Infected persons may have intermittent fevers, headaches, muscle and joint aches, and malaise. Itching of the skin, swollen lymph nodes, and weight loss can occur. Usually, after 1-2 years, there is evidence of CNS involvement, with personality changes, daytime sleepiness with nighttime sleep disturbance, and progressive confusion. Other neurologic signs, such as partial paralysis or problems with balance or walking may occur, as well as hormonal imbalances. The course of *untreated infection rarely lasts longer than 6-7 years and more often kills in about 3 years.*
T. b. gambiense infection (West African sleeping sickness) (CDC Description)
Outer Plasma Membrane Protein Coat of Trypanosomes
The surface of the trypanosome is covered by a dense coat of Variable Surface Glycoprotein (VSG), which allows persistence of an infecting trypanosome population in the host
– Enables an infecting T. brucei population to persistently evade the host’s immune system, allowing chronic infection via Shielding and Periodic antigenic variation
– The cell surface of the bloodstream form features a dense coat of variable surface glycoproteins (VSGs) which is replaced by an equally dense coat of procyclins when the parasite differentiates into the procylic form in the tsetse fly midgut.
Outer Plasma Membrane Protein Coat of Trypanosomes
1.) *Shielding*: dense nature of VSG coat prevents the immune system of the mammalian host from accessing the plasma membrane or any other invariant surface epitopes (such as ion channels, transporters, receptors etc.) of the parasite. The coat is uniform, made up of millions of copies of the same molecule; therefore the only parts of the trypanosome the immune system can ‘see’ are the N-terminal loops of the VSG that make up the coat
2.) *Periodic antigenic variation* – VSG coat undergoes frequent stochastic genetic modification – ‘switching’ – allowing variants expressing a new VSG coat to escape the specific immune response raised against the previous coat.
*Clinical effect of VSG cycle is successive ‘waves’ of parasitaemia (trypanosomes in the blood).*
The two properties of the VSG coat that allow immune evasion are:
Periodic Antigenic Variation
VSG is highly immunogenic, and an immune response raised against a specific VSG coat will rapidly kill trypanosomes expressing this variant. However, with each cell division there is a possibility that one or both progeny will switch expression to change the VSG variant that is being expressed.
Frequent changes and a diverse range of coats expressed by the trypanosome population means that the immune system is always one step behind: it takes several days for an immune response against a given VSG to develop, giving the population time to diversify as individuals undergo further switching events.
*Clinical effect of this cycle is successive ‘waves’ of parasitaemia (trypanosomes in the blood).*
Periodic Antigenic Variation
Chronic vs Acute Sleeping Sickness
Chronic: T. gambiense
Acute: T. rhodesiense
Chronic vs Acute Sleeping Sickness
Primary Stage Sleeping Sickness: Acute vs Chronic
Trypansosomal Chancre (Same for chronic and acute)
– Firm, tender, painful red nodule 1-3 weeks
Primary Stage Sleeping Sickness: Acute vs Chronic
Secondary Stage Sleeping Sickness: Chronic (T. gambiense)
*Fever*: Low, Irregular, Recurrent
*General Toxic Symptoms*: Backache, Headache, Tachycardia, Irrecular skin rashes (Circinate), Transient Edema of Face
*Lymphadenopathy*: Typically post-cervical
*Later anaenia, monocytosis
Slight enlargement of liver, spleen*
Secondary Stage Sleeping Sickness: Chronic (T. gambiense)
Secondary Stage Sleeping Sickness: Acute (T. rhodesiense)
*Fever*: High, Persistent
*General Toxic Symptoms*: Headache, Vomiting, Shivering, Edema Face, Serous Effusion, Bone Pain
*Lymphadenopathy
Myocarditis!!
Anemia
Purpura
Hepatits*
OFTEN DEATH at this stage!!
Secondary Stage Sleeping Sickness: Acute (T. rhodesiense)
Third Stage Sleeping Sickness: Chronic (T. gambiense)
*Progressive involvement of the CNS*
– General symptoms: Progressive Encephalitis
– Focal signs: uncommon, Dementia
– Brain Symptoms
Third Stage Sleeping Sickness: Chronic (T. gambiense)
Third Stage Sleeping Sickness: Chronic *Brain Symptoms* (T. gambiense)
Generalized Leptomeningitis (inflammation of the subarachnoid space)
Dura thickened and adherent
Edema with flat convolutions and dilated ventricles
Hemorrhage with softening
CSF turbid, increase in cells and protein, containing trypanosomes
– Perivascular cuffing with round and plasma cells, macrophages, and endothelial cells
Neurological Proliferation
Perssure atrophy neurones
Third Stage Sleeping Sickness: Chronic *Brain Symptoms* (T. gambiense)
Third Stage Sleeping Sickness: Acute (T. rhodesiense)
May have early onset of Encephalitis with rapid development of *coma*
Brain: Death before CNS involvement OR similar changes to chronic but more acute
Third Stage Sleeping Sickness: Acute (T. rhodesiense)
Chronic Sleeping Sickness: Epidemeology (T. gambiense)
Vectors of T. gambiense are Riverine species, hence disease is *often epidemic*
G. palpalis
G. tachinoides
Chronic Sleeping Sickness: Epidemeology (T. gambiense)
Vectors of T. rhodesiense are game-attacking species, hence disease is often more *sporadic*:
– G. morsitans
– G. pallidipes
– G. swynnertoni
Acute Sleeping Sickness: Epidemeology (T. rhodesiense)
HAT: Diagnosis
Wright / Giemsa stained
Perpheral Blood Smear or LN Aspirate
Acridine Orange Stain of Buffy Coat
Card Agglutination Test for Trypanosomiasis (CATT)
Mott’s Morula Cell
HAT: Diagnosis
Card Agglutination Test for Trypanosomiasis (CATT)
…..
Agglutination = positive?
Card Agglutination Test for Trypanosomiasis (CATT)
Mott's Morula Cell
Infiltrations of mononuclears in the perivascular space of the brain vessels including large abnormal plasma cells
– During the meningoencephalic stage, tissue biopsy typically shows a lymphoplasmacytic perivascular infiltrate containing plasma cells engorged with immunoglobulin
Mott’s Morula Cell
HAT: Management
If Lumbar puncture is positive….
DON’T NEED TO KNOW THIS
HAT: Management
*Pentamidine Isesthionate*
4mg/kg IM QOD x 10 doses
*Suramin*
Slow IV push 5mg/kg day 1 → 10mg/kg day 3 → 20 mg/kg days 5, 11, 17, 23, 30
– Watch for anaphylaxis
HAT: Management Pitfalls Non-CNS-Disease
DON’T NEED TO KNOW THIS
*Melarsoprol*
Uptitrate doses QD x 3, then 7 days off, x 4 cycles
– Extravasation will necrose tissue
– 10% die of arsenical encephalopathy
– Cure rate < 70% in parts of Uganda & Sudan - Jarisch-Herxheimer common... pre-Rx with Suramin or Pentamidine
HAT: Management Pitfalls CNS Disease DON’T NEED TO KNOW THIS
Effective only for T.gambiense infection
– IV only
– 14 amps / course… cost > $300
– Supply tenuous at best
DFMO
*Fly Control*
Mosquito Nets
Mosquito Traps -> blue color
HAT: Prevention
Extracellular, Antigenic Variation
Pathophysiology of Trypanosoma brucei
Toxic, not guaranteed to cure
– Extra-CNS with pentamidine or suramin
– CNS with above + melarsoprol
KNOW THIS
*HAT Rx* (Non-CNS vs CNS)
Chagas Disease Vector
All names for the same insect:
Barbiero “barber bug” (because of its need to draw blood from mammalian hosts in order to survive)
Vinchuca
Cone Bug
Reduviid Bug
Triatomine Bug
Kissing Bug (so-named because at night it descends from the crevices in mud walls or thatched roofs, attracted by both the warmth and CO2 content of exhaled breath)
*Co2/Thermal Sensors*
*Most common mode of transmission*
Chagas Disease Vector
American trypanosomiasis: caused by Trypanosoma cruzi
(Americans like to Cruise)
“Chagas disease”
18 million infected in *Latin America (LA)*
– 25% of population in endemic nations at risk = 90 million potential patients
– Infection usually starts in childhood
– Wide variability between regions
– Identified as *Most important parasitic disease in LA*
– The major cause of myocardial illness in LA
– Significant source of GI toxicity
– An important cause of mortality
Chagas: Epidemiology
Disability-adjusted life years (DALYs) in Latin America
?????????????????
Disability-adjusted life years (DALYs) in Latin America
Trypanosoma cruzi (Chaga's Disease) spread is...
*Traditionally Rural but has a high potential for Urban spread*
Map: regions where Chagas disease is felt to be endemic, according to the WHO: 2 problems with this map.
1.) Gives no sense for dramatic variability between rural and urban infection rates – contrast between rural and urban rates of infestation with the vector can be striking
2.) Doesn’t go far enough to the North! New infections are happening in our southwestern states – 3rd documented case of bug to human transmission in the US was in Tenessee in 1998
Trypanosoma cruzi (Chaga’s Disease) spread is…
Chagas: Life Cycle (T. cruzi)
*Triatomine Bug Stages*
1.) Triatomine (kising) bug takes a blood meal – passes *Metacyclic Trypomastigotes* in FECES, Trypomastigotes enter bite wound or mucosal membranes (e.g. conjunctiva)
*Human Stages*
2.) Metacyclic trypoastigotes penetrate various cells at bite wound site. Inside cells they transform into *Amastigotes*
3.) INTRACELLULAR: Amastigotes multiply by binary fission in cels of infected tissues
4.) Intracellular amastigotes transform into Trypomastigotes, then burst out of the cell and enter the blood stream
–> Trypomastigotes ingect other cells an repeat the cycle in new infection sites – clinical manifestations can result from this infective cycle
5.) Triatomine bug takes a blood meal – trypomastigotes ingested
*Triatomine Bug Stages*
6.) *Epimastigoes* in midgut
7.) Multiply in midgut
8.) *Metacyclic trypomstigotes* in hundgut
REPEAT
Chagas: Life Cycle (T. cruzi)
Vector-borne >80%
Blood transfusion 16%
Congenital 2%
Other routes <1% (i.e. oral, organ transplant, laboratory accident)
Chagas: Transmission (T. cruzi)
Infectious Stage of T. cruzi
1.) Triatomine (kising) bug takes a blood meal – passes *Metacyclic Trypomastigotes* in feces, Trypomastigotes enter bite wound or mucosal membranes (e.g. conjunctiva)
Infectious Stage of T. cruzi
Diagnostic Stage of T. cruzi
4.) Intracellular amastigotes transform into *Trypomastigotes*, then burst out of the cell and enter the blood stream
–> Trypomastigotes ingect other cells an repeat the cycle in new infection sites – clinical manifestations can result from this infective cycle
Diagnostic Stage of T. cruzi
Chagas: Enzootic / Sylvatic Reservoirs
????????????
Sylvatic cycle, with implications for control measures!
Chagas: Enzootic / Sylvatic Reservoirs
– Skin invasion & lymphatic blockage by amastigotes
– Further reticuloendothelial invasion
– Amastigotes furiously multiply and rupture host cells
– Hepatosplenomegaly
– BM infiltration & pancytopenia
– *Romana’s Sign*
– *Papudos*
– Acute Myocarditis
– Intense parasitism possible in innervated tissue
– Intense lymphocytic reaction seen around parasite nests
– Immune response may or may not quell infection
*Reminiscent of “hyperinfection” with strongyloides*
Chagas: Clinical Presentation – *Acute Disease* (T. cruzi)
Medical condition in which there is a reduction in the number of red and white blood cells, as well as platelets.
If only 2 parameters from the full blood count are low, the term bicytopenia can be used
– Anemia: hemoglobin < 13.5 g/dL (male) or 12 g/dL (female) - Leukopenia: total white cell count < 4.0 x 109/L. Decrease in all types of white blood cells (revealed by doing a differential count) - Thrombocytopenia: platelet count < 150×109/L. Disease marked by inappropriate and ineffective T cell activation that leads to increased hemophagocytic activity. T cell activated macrophages engulf erythrocytes, leukocytes, platelets, as well as their progenitor cells
Pancytopenia
Romana's Sign
*Unilateral painless periorbital swelling* associated with the acute stage of Chagas’ disease. Not to be confused with a chagoma.
Ooccurs 1-2 weeks after infection
Due to conjunctival swelling after contamination with the vector’s feces containing T. cruzi.
– Although very characteristic of Chagas’ disease, not all patients with the acute form develop Romaña’s sign.
Patients with R’s sign also have subcutaneous inflammatory nodule or nonpurulent unilateral palpebral edema and conjunctivitis with ipsilateral regional lymphadenopathy.
Romana’s Sign
Papudos
?????
Regional Lymphadenopathy….
Papudos
Chagas: Acute Myocarditis
May be fulminant
4-chamber enlargement
Pseudocysts formed
Chagas: Acute Myocarditis
10%
Chagas Acute Disease Pediatric Mortality
“hyperinfection” with strongyloides.
Chagas Acute and Chronic Disease are both Reminiscent of…
30% of acute cases evolve into chronic
Dormant phase may be 10-30 years
Two main target organ systems:
– *C*ardiac
– *G*I
(*Cha-Gut/Cha-Gas*)
*Reminiscent of “hyperinfection” with strongyloides*
Chagas: Clinical Presentation – *Chronic Disease* (T. cruzi)
Chronic Chagas: Cardiac Disease (T. cruzi)
Myocardial parasitism → cell death
4-chamber myocardial hypertrophy
Focal wall hypokinesia
Aneurysms
Thrombus formation → embolism
AV blockade, VT
– Hx and exam consistent with *CHF*, often R>L
– CXR demonstrates wild cardiomegaly, usually NOT due to effusion
Chronic Chagas: Cardiac Disease (T. cruzi)
Chronic Chagas: Cardiac Disease (T. cruzi) Chest X-Ray
Hx and exam consistent with CHF, often R>L
– CXR demonstrates wild cardiomegaly, usually NOT due to effusion
Chronic Chagas: Cardiac Disease (T. cruzi) Chest X-Ray
Autonomic nerve destruction → Hypomotility → megaviscus
– Auerbach plexus death
– Achalasia (faailure of smooth muscle/sphincter to relax)
– Megacolon
Chronic Chagas: Chronic GI Disease
Auerbach plexus death
death…leads to Achalasia?
Auerbach plexus death
Achalasia
A failure of smooth muscle fibers to relax, which can cause a sphincter to remain closed and fail to open when needed. Achalasia can happen at various points along the gastrointestinal tract; achalasia of the rectum, for instance, is Hirschsprung’s disease.
Achalasia
Megacolon
n abnormal dilation of the colon, often accompanied by a paralysis of the peristaltic movements of the bowel. In extreme cases, feces consolidate into hard masses inside the colon, called fecalomas (literally, fecal tumor), which can require surgery to be removed.
May be either acute or chronic
Megacolon
Chagas Tree
Pic
Primary –> Death or Early Latent —> Early Latent Arrested or Late Latent –> Early Latent Arrested Secondary Chagas or Tertiary —> Death
Chagas Tree
Wright / Giemsa stained blood smear
Different methods for Chronic vs Acute
*Blood or LN smear, biopsy, xeno, serology, PCR*
Chagas: Diagnosis
Smear or biopsy
Blood culture
Xenodiagnosis
PCR
*Acute* Chagas: Diagnosis
ELISA
IFAT
CFT
PCR
*Chronic* Chagas: Diagnosis
Xenodiagnosis
Diagnostic method used to document the presence of infectious disease microorganisms or pathogens by exposing possibly infected tissue to a vector and then examining the vector for the presence of the microorganisms or pathogens it may have ingested.
– bugs are fed on the patient’s tissue and the trypanosome is identified by microscopic examination of the bug’s intestinal contents after an incubation period.
Xenodiagnosis
– Rx for acute infection is toxic & unreliable
– Rx for chronic infection totally unreliable
– Management emphasizes control of sx’s
–> GI: Dilatation of achalasia, colostomy
–> Cardiac: Antiarrhythmetics, CHF mgmt… transplantation has been performed
Chagas: Management
Nifurtimox
Benznidazole
Posaconazole
Chagas: Treatment Options
Developed in 1972
Possible antimetabolite or superoxide burst
Used in acute phase, may prevent progression to chronic phase
Efficacy varies with region, 50-90%
Xenodiagnosis turns positive in 60-70% in 4 years
Taken PO, TID x 60-120 days
Moderate side effects
Not FDA approved, compassionate use via CDC
Nifurtimox
Developed in 1974
Antimetabolite
Used in acute phase, may prevent progression to chronic phase
Efficacy of 80% varies less with region
Taken PO, BID x 90 days
Significant side effects
Not FDA approved, unavailable in US
Benznidazole
Schering’s new toy
Antifungal
Superior to nifurtimox in acute animal infection
Human clinical experience “limited”
PO Solution only
Costs far too much $
Posaconazole
Bug Control!
Chagas: Prevention
1.) Vector-borne “extremely rare” (5 case reports) – Poor case-finding bias?
2.) High seroprevalence in domestic blood supply (1:35,000)
– Screening by serology since 1/07:
– >350 cases found so far… 30 referred to CDC
3.) HIV co-infection (IRIS after latent / occult Chagas)
– Consider Ab screen… but what utility?
4.) SOT recipients
– Same as above!
Chagas Disease: U.S. Issues
Rational Drug Design
???????
L.mexicana GAPDH (selective affinity)
Human GAPDH (steric inhibition)
Rational Drug Design
Toxic, perhaps 80% success in acute, no cure in chronic disease
Chagas Rx
Febrile illness, Chagoma (inflammatory nodule at bite site), LAN, *Myocarditis* → death (minority)
Chagas Acute Basic Steps
Asymptomatic → CHF, megaorgans
Chagas Chronic Basic Steps
Trypanosoma cruzi infection via reduvid bug
Acute: febrile illness, chagoma, LAN, myocarditis → death (minority)
Chronic: asymptomatic → CHF, megaorgans
Diagnosis: blood or LN smear, biopsy, xeno, serology, PCR
Rx: Toxic, perhaps 80% success in acute, no cure in chronic disease
Prevention: bug control
Future: Better drugs? Vaccines?
Chagas: Summary
350 million people at risk in 88 countries
12 million people infected
Annual Incidence: 2 million
Cutaneous Leishmaniasis: 1.5 million
Visceral Leishmaniasis: 0.5 million
Fatal if untreated
Epidemics in Northern India and at the junction of Eritrea, Ethiopia and Sudan
Southern Europe:
25-70% of adult VL cases are HIV related
1.5-9.5% of AIDS cases suffer from newly acquired or reactivated VL
Transmitted by sandflies
Drugs toxic
Drug resistance mounting
Vaccination has not been successful
Leishmaniasis Epidemiology
Leishmaniasis Clinical Forms
Cutaneous
Mucosal
Visceral
within macrophages?
Transmitted by Sandflies
Leishmaniasis Clinical Forms
Distribution of Visceral and Cutaneous Leishmaniasis
Pic
Distribution of Visceral and Cutaneous Leishmaniasis
Leishmania Life Cycle (all species)
Human Stages
1) Sand fly takes a blood meal, injects *Promastigotes* into the skin *INFECTIVE Stage*
2) Promastigotes are phagocytized by neutrophils that are rapidly recruited to the bite site, infected neutrophils release the parasites which are then consumed by Macrophages.
3) Promastigotes transform into *Amastigotes* inside macrophages. *DIAGNOSTIC Stage, INTRACELLULAR*
4) Amastigotes multiply in cells (including macrophages) of various tissues. *DIAGNOSTIC Stage*
*Sand Fly Stages*
5) Sand fly ingests infected macrophages when it takes a blood meal.
6) Ingestion of parasitized cell.
7) Amastigotes transform into *promastigotes* in midgut.
9) Promastigotes divide and migrate to the anterior midgut and foregut and probiscus.
REPEAT
Leishmania Life Cycle (all species)
Leishmania Vector and Resevoir
Lutzomyia – Phlebotomine Fly (Sandfly)
DOGS are an important resevoir (dogs wear Leashes, and play in the Sand)
Leishmania Vector and Resevoir
Leishmaniasis Infections
Cutaneous
Mucotaneous
Old World Cutaneous “Wet Type”
Old World Cutaneous
New World Cutaneous
Visceral —> Post Kala-Azar Dermal Leishmaniasis (PKDL)
Leishmaniasis Infections
Cutaneous Leishmaniaisis
Causes skin lesions, which can persist for months to years. Lesions usually develop w/in several weeks or months after exposure but occasionally first appear years later (e.g. in trauma or immunosuppression).
Lesions typically evolve from *papules to nodular plaques to ulcerative lesions*, with a raised border and central depression, which can be covered by scab or crust
– some lesions persist as *nodules*
– Lesions usually are painless but can be painful, esp if ulcerative lesions become infected with bacteria or if the lesions are near a joint
Healing typically results in atrophic scarring.
– Even patients with localized cutaneous leishmaniasis commonly develop more than one primary lesion (on same or different parts of body), satellite lesions, *regional lymphadenopathy (occasionally bubonic), and/or nodular lymphangitis* (sporotrichoid-like subcutaneous nodules). Sometimes lymphadenopathy is noticed first, before skin lesions develop
– L. braziliensis in Brazil (pics) – spreads along lymphatics
– L.mexicana cutaneous Leishmaniasis in Panama
Cutaneous Leishmaniaisis
L. mexicana cutaneous Leishmaniasis in Panama
“Chiclero’s Ulcer”
Espundia
Mucocutaneous Leishmaniasis due to L. braziliensis
Espundia
Mucocutaneous Leishmaniasis
(espundia) Metastatic sequela of New World cutaneous infection due to dissemination of parasites from skin to *naso-oropharyngeal mucosa*
– Adequate systemic treatment of cutaneous leishmaniasis thought to reduce the risk for mucosal disease
Usually becomes clinically evident within several years (up to decades) of original cutaneous lesions, which typically were untreated or treated suboptimally. However, mucosal and skin lesions may be noted concomitantly (mucocutaneous leishmaniasis), and some patients had subclinical cutaneous infection
Initial manifestations usually are *persistent, unusual nasal symptoms (stuffiness, bleeding)*, although oral or pharyngeal symptoms occasionally noticed first
Untreated may progress to *ulcerative destruction of the naso-oropharyngeal mucosa*
Mucocutaneous Leishmaniasis
*L. braziliensis*
Caused by species in the Viannia subgenus (L. braziliensis, L. panamensis and sometimes L. guyanensis); it also can be caused by L. (Leishmania) amazonensis
Mucocutaneous Leishmaniasis Species
Old World Cutaneous Leishmaniasis:
*Ulcerative, Rural type, L. major* (a majorly wet rural village)
– L. major develops as a s*mall red papule that ulcerates after 2 weeks, serous exudate produced* (“wet type”)
Zoonotic Resevoir: rodents
Incubation: 2 weeks – 2 months
Primary Lesion: Red, furuncle-like nodule on irregular, bright red base consisting of slough alternating with papules of proliferating granuloma
Crust: Hemorrhagic
Healing: 3-12 months
Old World Cutaneous Leishmaniasis: ”Wet Type”
*Ulcerative, Urban Type, L. tropica* (a dry, tropical city)
– L. tropica produces a *small red papule that ulcerates in 2-4 months into a dry ulcer* (“dry type”)
Ulcerative; urban type
Anthroponotic: Resevoir: humans and dogs
Incubation: 2-8 months
Primary Lesion: Papule with little tendency to ulcerate, dry when it does
Crust: Serous
Healing: Up to 24 months
Old World Cutaneous Leishmaniasis: ”Dry Type”
Old World Cutaneous Leishmaniasis
*Eastern Hemisphere*
*L. tropica complex or L. major complex*
– Etiologic agents include Leishmania tropica, L. major (also L. aethiopica, as well as L. infantum and L. donovani)
*Leishmania tropica recidivans*
Lesions on the face and forearm of a Syrian girl. These had been present for 4 years with slow healing in the center and multiple recurrences despite courses of intralesional meglumine antimoniate.
Old World Cutaneous Leishmaniasis
*Western Hemisphere*
*L. mexicana complex or L. (V.) braziliensis species complex*
– L. mexicana species complex (L. mexicana, L. amazonensis, and L. venezuelensis)
– L. (V.) braziliensis species complex/Subgenus Viannia (L. braziliensis, L. guyanensis, L. panamensis, and L. peruviana)
New World Cutaneous Leishmaniasis
Visceral Leishmaniasis or Kala Azar (L.infantum)
Caused by the *L. donovani complex (L.donovani, L.chagasi, L.infantum)*
Broad spectrum of severity and manifestations. Onset man be chronic, subacute, or acute. Affects internal organs (particularly, spleen, liver, and bone marrow).
– Incubation period ranges from weeks to months, but asymptomatic infection can become clinically manifest years to decades after the exposure in immunocompromised
Visceral Leishmaniasis or Kala Azar (L.infantum)
Visceral Leishmaniasis or Kala Azar (L.infantum) Clinical Manifestations
Fever
Weight loss (cachexia; wasting)
Hepatosplenomegaly (usually, Spleen more prominent than Liver)
Pancytopenia—i.e., anemia, leukopenia, and thrombocytopenia
High total Protein level and a Low Albumin level, with Hypergammaglobulinemia
Lymphadenopathy may be noted, particularly in some geographic regions (e.g. Sudan)
– HIV-coinfected patients may have atypical manifestations, such as involvement of the GI Tract and other organ systems
Visceral Leishmaniasis or Kala Azar (L.infantum) Clinical Manifestations
means black (kala) fever (azar) in Hindi—often is reserved for severe (advanced) cases of visceral leishmaniasis, although the terms kala-azar and visceral leishmaniasis sometimes are used interchangeably. If untreated, severe cases of visceral leishmaniasis typically are fatal, either directly from the disease or indirectly from complications, such as secondary (myco)bacterial infection or hemorrhage.
Kala-Azar
Post Kala-Azar Dermal Leishmaniasis (PKDL)
Syndrome characterized by skin lesions (erythematous or hypopigmented macules, papules, nodules, and patches), typically first noticed and most prominent on the face, that develop at variable intervals after (or during) therapy for visceral leishmaniasis
-Best described in cases of *L. donovani* infection in South Asia and East Africa
More common, develops earlier, and less chronic in patients in East Africa
– Persons with chronic PKDL can serve as *important reservoir hosts of infection*
(PKDL looks like “Pickled”, their faces have been pickled, they are in a real pickle)
Post Kala-Azar Dermal Leishmaniasis (PKDL)
*Biopsy for parasitologic demonstration of amastigotes in macrophages and culture*
1.) Microscopic detection of parasites in aspirates, smears, biopsies
2.) Culture –> Speciate parasites isolated with
– kDNA probes
– isoenzymes
– mAbs
3.) Serology (seldom used)
4.) DNA detection, PCR (seldom used)
Leishmaniasis Diagnosis
Methods for Direct Tissue Examination for Visceral Leishmaniasis
1.) Bone Marrow Aspirate
2.) Liver Biopsy
3.) Spleen Biopsy or Imprint
Methods for Direct Tissue Examination for Visceral Leishmaniasis
Methods for Direct Tissue Examination for Cutaneous and Mucocutaneous Leishmaniasis (Primary Lesion)
*Primary Lesion*
– Skin Scraping —> Giemsa Stain
– Biopsy
*Mucocutaneous Secondary Lesion*:
– Biopsy margin of nodule or ulcer
Methods for Direct Tissue Examination for Cutaneous and Mucocutaneous Leishmaniasis (Primary Lesion)
*Skin*: Ambisome, Pentavalent Antimonials (stibogluconate)
*Visceral*: Miltefosine or Ambisome
*Second Line*: Fluconazole, Itraconazole, Ketoconazole

*KEY Concepts: Pentavalent Antimonials (stibogluconate), Miltefosine: Visceral Leishmaniasis*

Leishmaniasis Treatment
Vector (Sandfly) control
Insect precautions
Animal reservoir control
Leishmaniasis Prevention
Sandfly (phlebotomine spp.) bites, warm, tropics (C./S. America, Africa, Middle East, India, Asia)
KNOW THIS
*Leishmaniasis Transmission*
– Replicates as amastigotes in macrophages (“*L*eish*M*aniasis *L*eases space in *M*acrophages”)
– Cutaneous Disease: Chronic Ulcers, L tropica, L major, L mexicana, L braziliensis complexes
– Mucocutaneous: L braziliensis complex
– Visceral Disease: Liver and Spleen enlarged with infected macrophages, L donovoni (infantum, chagasi)
KNOW THIS
*Leishmaniasis Pathology*
Trypanosomatids Overview
Pic – Memorize this!
Trypanosomatids Overview
Trypanosomatids Overview - Trypanosoma cruzi
At Risk: 100 million, C. and S. American
Infected: 16-18 million
Disease Outcome (Untreated): 10-30% die of complications after decades of infection
Vaccine Prospects: Poor, antigenic variation
Available Drugs: Only one, toxic and ineffective
Drug Resistance: Suspected
Trypanosomatids Overview – Trypanosoma cruzi
Trypanosomatids Overview - Trypanosoma brucei
At Risk: 60 million, Subsaharan Africa
Infected:300-500,000
Disease Outcome (Untreated): Uniformly fatal within 2 years
Vaccine Prospects: Poor, antigenic variation
Available Drugs: Toxic, difficult to deliver
Drug Resistance: Documented
Trypanosomatids Overview – Trypanosoma brucei
Trypanosomatids Overview - Leishmania spp.
At Risk: 350 million, Tropics and Subtropics
Infected: 2 million
Disease Outcome (Untreated): Visceral form (25% above) fatal
Vaccine Prospects: Poor, effective immune evasion
Available Drugs: Toxic, difficult to deliver
Drug Resistance: Documented
Trypanosomatids Overview – Leishmania spp.
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