Trypanosomiasis

TRYPANOSOMIASIS

BY: HARPREET KAUR

INTRODUCTION

• Definition: any tropical disease caused by trypanosomes and typically transmitted by biting insects, especially sleeping sickness and Chagas disease

• Causative agent: Trypanosoma

DOMAIN Eukaryota

KINGDOM Protista

PHYLUM Kinetoplasta

CLASS Kinetoplastida

ORDER Trypanosomatida

FAMILY Trypanosomatidae

GENUS Trypanosoma

CLASSIFICATION

Sub-genus Species

Schizotrypanum T. cruzi

Duttonella T. vivax

Nannomonas T. congolense

Trypanozoon T. brucei

T. b. brucei

T .b. rhodesiense

T .b. gambiense

T. equipedrum

T. evansi

Pycnomonas T. suis

DISEASE CAUSED BY TRYPANOSOMES Trypanosoma species

Species Distributn. Species exhibiting

disease

Vector Disease

T. b.

gambiense

West Africa humans Glossina palpalis

(Tsetse fly)

Trypanosomiasis

(Sleeping sickness)

chronic

T. b.

rhodesiense East Africa humans

Glossina

morsitans

Trypanosomiasis

(Sleeping sickness)

acute

T. b. brucei Africa

cattle,

antelope,

horses, camels

Glossina

pallidipes

Nagana

acute

T.

congolense Africa

cattle,

antelope,

horses, camels

Glossina

morsitans

Nagana

chronic

Species Distributn Species

exhibiting disease

Vector Disease

T. vivax Africa cattle, antelope,

horses, camels Glossina morsitans

Nagana

acute

T.

equiperdum Africa horses, donkeys

None (transmitted

during coitus)

Dourine

acute

T. evansi Africa camels, horses,

deer

Tabanid fly

Surra

T. cruzi

South and Central America

Reduvid bugs:

Rhodnius prolixus

Chagas disease

HISTORY 1841: Professor G. Valentin of Berne, Switzerland briefly described a protozoan found in the trout blood moving by means of its undulating membrane 1843: David Gruby, Paris discovered a similar organism in frog blood and because its swimming motion suggested the action of a corkscrew he called it Trypanosoma sanguinis 1880: Griffith Evans, found trypanosomes horses, mules and camels blood---- suffering from a fatal wasting disease called surra 1892: Alphonse Laveran, summarized all that was known about trypanosomes in 11 pages and 18 references

1895: discovered T. brucei as the cause of cattle trypanosomiasis (cattle nagana)

1901: Robert Michael Forde first observed trypanosomes in human blood in The Gambia 1902: Joseph Everett Dutton proposed the species name Trypanosoma gambiense 1902: Aldo Castellani found in CSF of sleeping sickness patients and suggested that they cause sleeping sickness 1903: Bruce provided conclusive evidence that sleeping sickness is transmitted by tsetse flies

1904: animal pathogenic trypanosome species T. congolense was discovered by Alphonse Broden 1905: T. vivax was discovered by Hans Ziemann 1909: Friedrich Karl Kleine showed cyclical transmission of T. brucei in tsetse flies 1909: Carlos Justiniano Ribeiro Chagas first described Chagas disease 1910: John William Watson Stephens and Harold Benjamin Fantham recovered human pathogenic trypanosome species, T. rhodesiense Three major outbreaks have occurred in recent history: one from 1896 to 1906 primarily in Uganda and the Congo Basin and two in 1920 and 1970 in several African countries.

Trypanosomiasis

African trypanosomiasis

West African Trypanosomiasis

East African Trypanosomiasis

American Trypanosomiasis

Glossina (tsetse fly) Triatoma (winged bug)

African Trypanosomiasis • Also called Sleeping sickness (humans)

• nagana, souma and surra (animals) • transmitted by infected tsetse flies in rural sub-Saharan Africa • caused by 2 different parasites: T. b. gambiense found in 24 countries of Central Africa and western Africa Accounts for 98% of the reported cases & cause acute infection

T. b. rhodesiense found in 13 countries of eastern and southern Africa Accounts for below 2% of the reported cases & cause chronic infection

-70 million are at risk in36 countries of sub-saharan Africa where the disease occurs regularly

Geographic distribution of both East and West African strains of T. brucei

Tsetse fly •Include all the species of genus Glossina •Size of honey bees and grey-brown •29-31 species have been identified •Almost all exclusively found on African continent south of Sahara •6 recognised as vector of sleeping sickness and incriminated in transmission of two pathogenic human trypanosomiasis •Both male and female flies feed by cutting through the skin, rupturing small blood vessels and feeding on the pool of blood formed, intermittently ejecting saliva, with metacyclic trypanosomes if infected

T.brucei brucei- Glassina morsitans – Wild Games & domestic animals

T.b gambiense- G.palpalis- Man, Reptiles & Birds

G.pallidipes

G.tachinoides- Mammals other than man

- Shade & Moisture loving vector

- Found in Scrubs & Shaddy traces near water

- Not travel far from their breeding place

T. b rhodesiense- G.morsitans

G.swinnertoni Feed on Game animals G.pallidipes

T. eqipedrum & T. evansi -Horseflies(Tabanus sp.) & Stable flies (Stomoxys sp.) -So not restricted to African continent

MORPHOLOGY

Exist in two interchangable forms:

Trypomastigotes: in blood/ lymph/

tissue spaces of various organs & CNS

is terminal and fatal

Epimastigotes: in salivary gland of

host and culture media.

Trypomastigote (polymorphic trypanosomes)

Spindle shaped----Central nucleus ˗ free flagellum--- undulating

membrane

•Long slender form (30µ): active motile with free flagellum

•Short stumpy form (15µ): sluggish without free flagellum

•Intermediate form (20µ): with a short free flagellum

African Trypanosomiasis life cycle

Life cycle of Trypanosoma

b. gambiense & T. b. rhodesiense

Mechanism of disease transmission by Glossina

Pathogenesis and Clinical Picture

Pathogenesis

Bite of tsetse fly → Trypomastigote enter Subcutaneous pool of blood

Some-Blood stream Majority- Entangle in tissue spaces

Autoimmune Rxn. Damage Massive release of Kinin - Large no. of non specific Igs against exoantigens release - Kinin: Heavy infiltration of Macrophages Macrophages clear trypomastigotes in tissue spaces

- Oedema: Increased capillary permeability of tissues

Winterbottom sign

Sleeping sickness

CNS

- Increase of glial cells throughout the CNS - Cerebral Perivascular Cuffing with mononuclear cells - Cerebral softening due to thrombosis of cuffed vessels - Choroid plexus congestion & infiltration with monocytes & Parasites - Heavy infiltration in leftomeninges

Diagnosis

Microscopy

Serology

DNA detection

Animal inoculation

Diagnosis Diagnosis of T. b. gambiense HAT follows a three-step pathway: screening, diagnostic confirmation, and staging Diagnosis of Sleeping sickness depends on demonstration of trypanosomes in: blood, CSF or lymph node aspirates Primary Screening: includes serology 1) CATT (Card Agglutination Test for Trypanosomiasis)/ T.b.gambensie 2) RDT (Rapid diagnostic test) for T. b. gambiense 3) CLN (Cervical lymph node) palpation and puncture Antigen detection test Identification of antibodies that are suitable for antigen detection assays and antigens for use in developing antibody detection tests are running concurrently

a) Card Agglutination Test for human Trypanosomiasis • field and laboratory test for serodiagnosis and mass screening of the • population at risk • in West and Central Africa

• direct card agglutination test for detection of trypanosome specific antibodies in blood, serum or plasma

• Freeze dried suspension of purified, fixed and stained trypanosomes of a cloned predominant Variable Antigen Type (VAT LiTat 1.3) of T.b.gambiense

• One drop of reagent is mixed with one drop of blood and shaken for 5 min

• result visible to the naked eye

• Sensitivity from 87- 98%, specificity- around 95%

• False-negative- Patients infected with strains of trypanosomes that lack or do not express the LiTat 1.3 gene

b) micro-CATT:

small quantities of antigen (one-fifth of the standard amount) with blood- impregnated filter paper (FP)

rapid decrease in sensitivity when FP more than 1 day at ambient temp.

reading and interpretation of the agglutination patterns can be difficult

c) macro-CATT:

Standard amount of antigen and a higher volume of FP elute

Sensitivity- 91%

FP can be stored for up to 2 weeks at ambient temperature (25 to 34°C)

2) Rapid Diagnostic test/ T. b. gambensie • Alternative to CATT • Tests are packed individually and are stable at a temperature of 40°C for up to 25 months • Performed on fresh blood obtained from a finger prick, and no instrument or electricity is required • RDT detects host antibodies to infection

3) Cervical lymph node (CLN) palpation and puncture

Other serological tests:

a) LATEX/T. b. gambiense:

- developed- a field alternative to the CATT

- combination of 3 purified VSGs, LiTat 1.3, 1.5, and 1.6, coupled with suspended latex particles

-higher specificity- 96 - 99% but similar sensitivity- 71 - 100%

b) Immunofluorescence assays:

- highly sensitive and specific

- sensitivity as low as 75% when used with impregnated FP

c) ELISA:

- with serum, FP elutes, and CSF

Diagnostic Confirmation by Trypanosome Detection 1. Microscopy: Samples- Blood and Lymph node aspirate (40-80%) - Should be examined within 20min of collection - In gambiense- No. of parasites in blood & other body fluids- very - Multiple sampling & conc. tech required a) Thick/thin blood films- Good diag. tech - repeat daily sampling increase probability - very low sensitivity Staining Rxn- • Leishman/Ramnowsky stain •Cytoplasm & undulating memb. → pale blue •Nucleus- Reddish purple/Red • Kinetoplast & flagellum- Dark red

Blood smear from a patient with T. b. gambiense

Blood smear from a patient with T. b. rhodesiense

Blood films with T brucei trypomastigotes

2) Microhematocrit centrifugation technique (Mhct): • Capillary tube centrifugation technique or as the Woo test

3) Quantitative buffy coat:

• concentrating the parasites by cf & staining nucleus and kinetoplast of trypanosomes with acridine orange

• 95% sensitivity

• Can detect more patients with low parasitemia than Mhct

4) Mini-anion-exchange centrifugation technique:

• introduced by Lumsden et al., 1974

Stage Determination By CSF Examination

1) White blood cell count: >20 cells/µl in CSF should be treated for second-stage HAT

2) Trypanosome detection: Less sensitivity→ double centrifugation method

3) Antibody detection: - high levels of IgM- marker of second-stage HAT - latex agglutination test for IgM in CSF (LATEX/IgM) - sensitivity & specificity- 89 and 93%, respectively

Other Diagnostic Approaches

1) Antigen detection tests:

• distinct between active and cured HAT

a) Specific antigen detection by ELISA

b) Card indirect agglutination test for trypanosomiasis (TrypTect CIATT; Brentec Diagnostics, Nairobi, Kenya)

2) Invitro cultivation of Trypanosomes: • Not NNN • Medium of Ringer’s soln. + NaCl +Tvrode’s solution Citrated human blood ↓ Long-slender forms (Mid-gut forms) • Not useful for routine diagnosis due to the time consuming method

3) KIVI: • Kit for Invitro Isolation of trypanosomes in field • Requires days to culture to get detectable amount •Imp.- Standard for evaluating Quicker diag. tests

4) Animal Inoculation: •neonatal, immunosuppressed (e.g., Mastomys natalensis) rodents

5) Proteomic Novel & Accurate Test:

• By identifying distinct serum proteomic signatures characteristic of HAT by SELDI-TOF

• Sensitivity- 100%

• Specificity- 98.6% (Papadopoulos et al., 2004)

6) Molecular dipstick test:

• HAT-PCR-OC

• For rapid detection of amplified T.brucei DNA

• PCR product visualised on dipstick through hybridization with a gold-conjugated probe (Oligochromatography)

• 5min

• Controls for PCR & DNA migration, incorporated

• Can detect 5fg of pure T. brucei DNA

• 1 Parasite/180µl of blood

• 100% Sensitivity & Specificity (Deborggraeve et al., 2006)

7) PCR for diag. of T. b. gambiense:

• PCRs targeting repetitive sequences- more sensitive in theory

• None of them have been validated for diagnostic purposes

Sensitivity- 99.4%

Specificity- 98.6%

(Penchenier et al., 2000)

Drug Use Drawbacks

Pentamidine Effective against early-

stage gambiense disease • Adverse side effect •Non-oral route

Suramin

Effective against early-stage

gambiense & rhodesiense disease

•Adverse side effects •Non-oral route

Melarsoprol

First line drug for late stage

gambiense & rhodesiense disease involving CNS

•Adverse side effects, especially encephalopathy

•Fatal in 1-5% of cases •Parasite resistance •Non-oral route

Eflornithine Effective against late-

stage gambiense disease involving CNS

•High cost •Not effective against T.

rhodesiense •Non-oral route - has to be given intravenously (needs

Treatment of African Sleeping Sickness

American Trypanosomiasis • Also called Chagas Disease • transmitted by infected winged bugs, kissing bugs • leading cause of heart failure in Latin America • affects 16 to 18 million people- Central and South America •killing about 50,000 every year •100 million people (25%)- Latin America is at risk •6 million people- Brazil.

The human disease occurs in two stages: Acute stage Chronic Stage -occurs shortly after initial infection - after a latent period that may -generally seen in children last many years -characterised by - asymptomatic - lesions irreversibly affect • fever internal organs namely the •Swelling of lymph nodes heart, oesophagus and colon •enlargement of the liver and spleen and the peripheral nervous •local inflammation at the site of system infection -Swelling around one eye -25%-cardiac symptoms- death (Romana’s sign may occur if insect -5% develop digestive damage faeces are rubbed into it) -3% peripheral nerve damage

Triatomine bugs • Also called reduviid bugs, kissing bugs, assassin bugs, cone-nosed bugs, and blood suckers • 138 species of triatomine have potential to transmit T. cruzi • But 5 are epidemiologically important: Triatoma infestans Rhodnius prolixus Triatoma dimidiata Triatoma brasiliensis Panstrongylus megistus R. prolixus

• typically found in the southern United States, Mexico, Central America, and South America

Geographical Distribution of Chagas Disease

MORPHOLOGY

Trypomastigote (monomorphic)

Slender shaped (20µ) –Central nucleus – C or U-shaped–Free flagellum 1/3 Body--Large bulging peripheral kinetoplast

Amastigote Obligatory intracellular – mainly in cardiac & Skeletal muscles – Brain meninges – Nerve ganglia – cells of GIT Epimastigote (vector only) Spindle shape– Kinetoplast anterior to central nucleus–Undulating membrane is short – terminal free flagellum

American Trypanosomiasis Life cycle

Mechanism of Disease Transmission by Triatome

Pathogenesis and Clinical Features

Acute Form

Chagoma occurs at the site of bite.

Parasite reaches regional lymph nodes

Blood

Organs and tissues

Symptoms: Fever, enlarged lymph nodes, skin rash, enlarged liver & spleen.

Romana’s sign (Unilateral conjunctivitis appear suddenly together with oedema of upper & lower eye lids & cheek)

Meningoencephalitis, heart failure

Death or pass to Chronic form

Chronic form Parasite produces antigens similar to patient’s self antigens: The body produces auto-antibodies that cause damage to: Heart muscle fibres: Exacerbation of infection in immunosuppressed patients

Oesophageal muscle fibres: megacolon and constipation

Colon muscle fibres: megaoesophagus and dysphagia Destruction of Auerbach’s plexus

CNS or thyroid gland: congestive heart failure

Amastigote form of T.cruzi

Laboratory Diagnosis Parasitological Diagnosis Immunological Diagnosis Molecular Diagnosis

Parasitological Diagnosis Direct Methods Indirect Methods

- Microscopic Examination - Hemocultures - Culture - Xenodiagnosis - Animal Inoculation

Microscopic Examination Drop of blood (5 mL)- rapid movements of T .cruzi trypomastigotes (100 fields) Stained thin and thick blood smears Less sensitive

Microhematocrit • Collect blood in 1-6 heparinized capillary tubes of 75 mL • Centrifuged for 5-10 minutes • Examine the buffy coat in microscopy for trypomastigote

movements

Strout method • 3 ml of blood incubated for 1 hour at 37°C. • Serum is collected & centrifuged (at 160g for 3 min)

• The supernatant - second centrifugation (at 400g for 5 min)

• precipitate of last centrifugation examined as fresh blood

Culture Microscopy fail NNN , 22-240 C 4th day & every week for 6 weeks Epimastigotes & Trypomastigotes

Indirect Methods Multiplication of parasites from the collected samples in the culture medium Performed on liver infusion tryptose medium Maintained at 28°C and observed monthly over 4-6 months

Disadvantages

Examinations are long and require highly specialized personnel The results are available only 1-6 months after the test Less popular Less sensitive (25-70% )

Xenodiagnosis Insects can be put either directly in contact with the patient's skin or with anticoagulated blood through a thin latex membrane intestinal contents of the insects are examined 30-60 days later to observe for metacyclic trypomastigotes

Animal Inoculation Specimens are inoculated intraperitoneally into mice Tail blood collected after 10 days & examined for motile trypanosomes Mice killed after 2 months & tissue from heart examined for amastigotes

Immunological Diagnosis

3 commercially available serological tests are used routinely for investigation of T . cruzi–specific antibodies

Indirect hemaglutination- Sensitivity- 96-98% Immunofluorescence (IFI) Enzyme-linked immunosorbent assay (ELISA) Diagnosis of 98% of patients who are chronically infected IFI and ELISA are also suitable for the detection of IgM (congenital infection) Complement-mediated lysis- helps to detect antibodies disappearing soon after treatment Direct agglutination test (DAT)- Field Use The Western blot- Confirmatory Diagnosis

Imaging Studies Radiography of chest ,colon, esophagus Electrocardiogram, Holter monitoring & exercise testing , Esophageal endoscopy and manometry

Treatment

Benznidazole

5–10 mg/kg per day in two divided doses for 30–60 days

Nifurtimox

8–10 mg/kg in three divided doses after meals for 30–120 days

Prevention of African Trypanosomiasis No vaccine available against Trypanosomiasis

Wear long-sleeved shirts and pants of medium-weight material

in neutral colors that blend with the background environment

Inspect vehicles before entering- flies attracted to the motion and dust from moving vehicles

Avoid bushes- tsetse fly is less active during the hottest part of the day but will bite if disturbed

Use insect repellent- Permethrin- impregnated clothing and insect repellent have not been proved to be particularly effective against tsetse flies, but they will prevent other insect bites that can cause illness

Prevention of American Trypanosomiasis Collective prophylaxis By using sprays & paints containing insecticides By improving housing & sanitary conditions in rural areas A mosquito net Testing of blood donars Treatment of infected individuals Personal prophylaxis Lab personnel should wear gloves & skin and eye protection Applying insect repellent to exposed skin Proper washing and cooking

Control Control of African trypanosomiasis rests on two strategies: • reducing the disease reservoir • controlling the tsetse fly vector

for T. b. gambiense • humans are significant disease reservoir • main control strategy for this subspecies is active case-finding through population screening • treatment of the infected persons that are identified • Tsetse fly traps are sometimes used as an adjunct

For T. b. rhodesiense • variety of animal hosts- reducing the reservoir of infection is

more difficult • Vector control- primary strategy- done with traps or screens, in

combination with insecticides and odors that attract the flies

Treatment of American Trypanosomiasis Antitrypanosomal drug treatment is always recommended For acute, early congenital, and reactivated T. cruzi infection for chronic T. cruzi infection in children aged <18 years old

In adults, treatment is usually recommended

treatment drugs - benznidazole and nifurtimox

Benznidazole: 5–10 mg/kg per day in two divided doses for 30–60 days

Nifurtimox: 8–10 mg/kg in three divided doses after meals for 30–120 days

Trypanosomiasis in India •1974- Two cases of self-limiting febrile illness due to Trypanosoma lewisi reported of an adult couple who lived in a rat-infested village •symptoms resolved without specific treatment after two to three days •2004- the first case of human Trypanosoma evansi -- induced trypanosomiasis was formally identified in India due to lack of apoL-1 • Unusual case of Trypanosoma evansi reported from rural parts of Chandrapur district in Maharashtra in an adult male farmhand with recurrent febrile episodes •responded to suramin

•2007- human T. evansi infection were reported in Maharashtra State, including a two month old infant in Mumbai •2007- 57 year old man from district Pune got infection from T. lewisi • had chronic intermittent fever, anemia, firm hepatosplenomegaly and edema on feet • Treated with suramin •2010- a 37 day-old infant in Uttar Pradesh • Trypanosomiasis confined to animals in India • T. lewisi parasite of rats (Rattus rattus and Rattus norvegicus) tramsmitted by fleas • T. evansi infects buffalo, camels, horses, pigs, cattle, dogs, jaguars and tigers

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