1. TRYPANOSOMES& LEISHMANIA)

2. Introduction
Both Trypanosomes and Leishmania are parasitic protozoa also known as haemoflagellates.
They require two hosts to complete their life cycle and are therefore called digenetic or hetero xenous.
They live in the the blood and tissues of human and other vertebrate hosts and in the gut of insect vectors.
There are four morphological forms of clinical significance associated with haemoflagellates: amastigote , promastigote, epimastigote , and trypomastigote .
Multiplication is by binarry fission.No sexual cycle is known.

3. MORPHOLOGICAL STAGES
AMASTIGOTE STAGE: it is the stage in which T.cruz and Leishmania are found intracellular in vertebrate hosts.
PROMASTIGOTE: Infective stage of Leishmania found in the midgut and proboscis of the insect vector.
-its also the form in which leishmania occur in cultures in vitro
EPIMASTIGOTE:The stage in which T.gambiense and T.rhodensiense occur in the salivary glands of the vector tse- tse fly, and T.cruzi in the midgut of the vector reduviid bug.
TRYPOMASTIGOTE:Infective stage of tryponosomes found in the vector arthropod and in the blood of the infected vertebrate.

4. A schematic drawing of the trypanosome

5. KEY
A-the anterior flagellum. B-the underlying complex cytoskeleton. C-the nucleus. D-the mitochondrion. E-the kinetoplast (mitochondrial genome). F- glycosome (a unique organelle where glycolysis occurs). G-the flagellar pocket. H-the basal body. I- Golgi apparatus. J-endoplasmic reticulum. K-the undulating membrane. L-attachment of the flagella to the undulating membrane. M-attachment of the flagella directly to the cell body.

6. TRYPANOSOMES
Taxonomic classification: Phylum:Sarcomastigophora Sub-Phylum:Mastigophora Class:Zoomastigophora Order:Kinetoplastida Family:Trypanosomatidae Genus:Trypanosoma Specie;Brucei Subspecie:gambiense,rhodensience

7. Trypanosomes cont
Haemoflagellates of the genus trypanosoma occur in the blood of mammals as mature elongated trypomastigotes.
All are transmitted from one vertebrate to another through biological vectors. In the vector , the Trypanosoma follow one of two modes of development . in some , the Trypanosoma migrates to the mouth parts of the vector (salivaria Trypanosoma ) , example T.rhodesiense and T.gambiense , which are transmitted by the bite of tsetse flies. In other , the Trypanosoma migrate to the hindgut and are passed in feces (stercorarian Trypanosoma ) , example is T.cruzi which is acquired by rubbing the feaces of the vector bug into the wound caused by its bite.

8. Classification 1.Trypanosomes infecting man
2.Trypanosomes infecting several animal species,

9. Trypanosomes infecting man
Name
Man
Type of a disease
T.Brucei subspecies(human strains)
-T.brucei gambiense
-T.brucei rhodesiense yes
Yes
yes
West Afican sleeping sickness(milder chronic infection)
-East African Sleeping sickness(more acute infection)
T.cruzi
T.rangeli
South American trypanosomiasis or chagas disease
Non pathogenic causing harmless human infection

10. Trypanosomes infecting animal species
Name
Type of animals
Disease
T.brucei(animal strains)ie
-T.bruce brucei
African cattle and wild game animals
nagana
T.evans
Horses,mules,camels,elephants
Surra in india
T.equiperdum
Horses &mules
Stallion’s disease (sexually),no insect vector
T.lewisi
Rats worldwide
Harmless infection,vector is the rat flea,

11. AFRICAN TRYPANOSOMIAS (Sleeping sickness)
African Trypanosomiasis (African Sleeping Sickness) exists in two geographically and clinically distinct forms; East African and West African. The disease is transmitted by the bite of both the male and female tsetse (Glossina species). T. brucei gambiense is the agent of central and West African sleeping sickness. Man is the primary reservoir for this agent.
Man, wild and domestic animals can serve as reservoirs for T. brucei rhodesiense, the agent of central & East African sleeping sickness.

12. African trypanosomiasis The tsetse fly

13. African trypanosomiasis - Distribution
West African = Trypanosoma gambiense
East African = Trypanosoma rhodesiense

14. Morphology and Life cycle
The morphology and life cycle of the human strains of T.brucei(T.gambiense and T.rhodesiense) are identical.
. These parasites are polymorphic in vertebrate host, ranging from long, slender trypomastigotes with a long free flagellum. They also have small kinetoplast near the posterior end and undulating membrane is conspicuous

15. Life cycle
Human infection is acquired by the bite of the vector tsetse fly.The infective form of the parasite is metacyclic trypomastigote.On introduction into the dermis,this proliferates initially at the site of inoculation and then through the lymphatics,enters the blood stream.

16. Life cycle cont
In the blood three forms of trypanosomes are found,the long slender trypomastigote,a short broad form with the flagellum present or absent and and an intermediate form.
The trypomastigote are about 15 to 40um long and 1.5 to 3.5um broad.
When a vector tse tse fly feeds on a person with parasitaemia,it takes the trypomastigote along with its blood meal,particularly the short broad forms.

17. These become long slender forms in the midgut and hind gut of the fly,where they proliferate and reach the salivary glands where they become broad epimastigote,multiply and fill the cavity of the gland.
The fly becomes infective when the epimastigote is transformed into metacyclic trypomastigote.
It takes about 3 wks from the time of the blood meal for the fly to become infective.
There after the fly remains infective for life,abt 6 mnths.

18. West African sleeping sickness
Caused by T.b.gambiense
The infection is endemic in west and central africa btn 15 degrees and 18 degrees latitudes bt sometimes it can be an epidermic.
Principal vectors-the riverine tsetse flies Glossina palpalis and G.tachinoides
Definitive host-Mostly cattle and humans

19. Pathogenisis/symptomatology of T.gambiense
- incubation period is abt 1-2 wks
In the vertebrate host, they live in blood, spleen, lymph nodes and CSF. They are the causative agents for chronic form of African sleeping sickness disease.
There is an initial period of parasitaemia,following their localization in the lymphnodes,a stage marked by intermittent fevers,chills and headache.
There is hepatosplenomegaly and glandular enlargement particularly in the posterior cervical region(Winterbottom).
On invading CNS(occurs after several months),sleeping sickness stage starts,marked by headache,mental dullness,apathy and sleepness.patient falls into profound coma followed by death from asthenia.
Histopathology shows chronic meningoencephalitis.

20. East african sleeping sickness
Distribution: Caused by T.b.rhodesiense.
Extends from southernSudan,uganda,kenya,tanzania,zambia,zim bwabwe,malawi,botswana and northen mozambique.
Epidemiology:Principal vectors- G.morsitans,G.palpalis and G.swynnertoni.
Though the infection is transmitted by the vector frm man to man,the disease is actually Zoonosis,with the reservoir being wild game animals and cattle.

21. Pathogenesis/symptomatology
The disease is more acute,symptoms begins within 5 to 7 days.
Death occurs in a few weeks to a year.
Pathogenisis is similar to that of T.gambiense but the disease is more rapid and fulminant,the patient dies before CNS invasion.
Fever,weakness,rapid loss of weight and myocarditis are the usual manifestations.
Mania and delusion may occur but the typical sleeping sickness picture is seldom seen.

22. DIAGNOSIS
Medical diagnosis and physical findings are important for diagnosis.
Symptoms for diagnosis: irregular fever,enlarged lymphnodes (winterbottoms sign), delayed sensation to pain (kerandels sign) and erythmatous skin rash.

23. African trypanosomiasis Disease

24. Diagnostic Laboratory tests
Diagnosis is established by the demonstration of the trypanosomes in the peripheral blood,bone marrow,lymph nodes or CSF and sometimes spleen puncture.
Methods available-
*Direct microscopy of stained or unstained preparations
*Cultivation in Weinman’s or Tobie’s medium and inoculation into rats
*Several serological tests are used to detect antibodies
-Direct agglutination
-indirect haemagglutination
-gel precipitation immunofluorence and ELISA

25. African trypanosomiasis Diagnosis

26. TREATMENT In early cases 1.Suramin 2.pentamidine
In late cases associated with neurological involvement
-Melarsoprol.

27. PREVENTION OF AFRICAN TRYPANOSOMIASIS
Control:
-Protection while sleeping by raise sleeping area off ground, or sleep in netting.  -DDT- poison  -Keep village clean of dogs, raccoons and other possible hosts with the parasite
Avoiding bushes,tse tse fly is less active during the hottest period of the day,it rests in bushes but may bite if disturbs.

28. SOUTH AMERICAN TRYPANOSOMIAS(chaga’s disease)
American Trypanosomiasis (Chagas' Disease)
found in tropical and sub‑tropical areas of Central and South America, as well as the southern U.S. Incidence in U.S. is increasing due to immigration from endemic areas.
Causative agent: Trypanosoma cruzi

29. The vector : the triatomid bug also referred to as the reduviid bug,conenose bugs or "kissing bug", due to its predilection for biting on the face of sleeping victims.
Definitive Hosts::-Humans, dogs,cats, armadillos, raccoons, and other small mammals.
Intermediate Hosts:-Reduviid bugs Rhodnius prolixus, Panstrongylus megistus, and Triatoma infestans.--
Transmission:-Stercorarian- posterior station
Live In cracks and crevices of poor quality houses
Feed at night on sleeping people
Parasites develop in the hindgut

30. Triatomid bug

31. Life cycle
When a triatomine bug bites an infected individual it ingests trypomastigotes—. Within the gut lumen(mid gut), trypomastigotes differentiate into epimastigotes.
Epimastigotes migrate to the hindgut,multiplies and becomes infective metacylic trypomastigotes.Others continue multiplication.once infective,the bug remains so for life.
These metacyclic trpomastigotemigrate to the rectal sac.

32. Life cycle continue
Trypomastigotes are discharged with faeces when the bug is feeding.
Parasites enter the body through the bite wound or mucosa eg.conjuctiva & mouth by scratching or rubbing.
In man, there is local multiplication at the point of entry in macrophages.
Parasites enter and multiply within virtullay any cell but prefers the following tissues: cells of the RES,lymphatic tissues,muscular tissues( skeletal and smooth muscles),cardiac muscles and Nervous tissue-CNS or any other but mainly nervous tissue of the intestine

33. Upon invasion of the cell trypomastigote losses its flagellum and undulating membrane and divides by binarry fission to form amastigote,which also continues to divide and fill and destroys the infected cell.
Both amastigote & trpomastigote are released by the cell.
Trypomastigote are ingested by the reduviid bug when it obtains its blood meal
Trypomastigote transform into epimastigote which multiply in the posterior portion of the midgut
After 8-10 days,metacyclic trpomastigote develop and are passed in feces.

37. Clinical manifestations
Acute Phase (2‑4 wks after bite)
1) Chagoma development (erythematous subcutenous nodule, seen area of bite on the face, minority of patients)
2) Unilateral edema of eyelid (Romana'a sign, follows conjunctival inoculation)
3) Fever, vomiting, anorexia, localized lymphadenopathy, hepatosplenomegaly
4) Parasitemia occurs approximately 3 weeks post infection; persists several weeks to months.
5) 5-10% mortality rate due to acute myocarditis or meningoencephalitis   

38. Congenital Chagas' Disease
1)occurs in 2-4% of infected mothers, transplacental transmission
2) May be transferred in breast milk
3) High death rate within days to weeks of birth, usually due to meningoencephalitis

39. Chronic Asymptomatic/Indeterminate
1) Clinically asymptomatic, serologically positive
2) Low level parasitemia may occur
 Chronic Symptomatic Phase (months to years after initial symptoms)
1) Occurs in one third of infected individuals
2) Myocardial involvement; enlargement, congestive cardiomyopathy, arrhythmias, congestive heart failure (chronic heart damage)
3) Megacolon (10%), enlargement of esophagus (35%)
4) Death may occur due to fatal arrhythmias or cardiac rupture

40. Diagnosis
1.clinically
*acute infections-endemic d’se-who develops acute febrile illness with lymphadenopathy and myocarditis.presence of chagoma and romana’s sign
* chronic infn-cardiac and intestinal symptoms in people lives under deprivation conditions
2.Parasitological
*Demonstration of trypomastigote in peripheral blood smears
-Thick and thin smears should be prepared
-trypomastigote often appears in a C shaped form

41. Dx continue
3.Culture - If parasites are scanty,culture blood aspirate frm chagoma or enlarged lymph nodes or tissue *In NNN(Man Neal Nicole) media at 25degrz for up to 30 days. 4.Xerodiagnosis-most valuable for chronic infxns -by allowing a parasite,free reduviid bug to bite the patient and by demonstrating the parasites in iys intestinal content. 5.Serological: in late chronic stages when parasites can not be demontrated in blood -Complement fixation,direct agglutination,indirect haemaglutination,immunofluorescence, and ELISA

42. TREATMENT
-No effective specific Rx is available But nifurtimox and benznidazole hv bn succesful in acute phase 1.Nifurtimox : Dose-8-10mg/kg daily increasing to 15mg/kg for days 2.Benznidazole: 5-7mg/kg daily for days -Allopurinol and ketoconazole hv also bn found useful.

43. Prevention Principal:destroy the vector & protect human frm bite
1.improvement of housing ie.by plastering walls to cover cracks and crevices
2.Destruction of triatomine bugs in the houses by using insecticides –like chlorinated hydrocarbon insecticides.
3.personal protection-bed nets as bugs are nocturnal feeders.
4.Prevent transmission induced infn by serological screening of blood donors
5.Lab precaution: use gloves and eye protection
-handling of all clinical specimens by using universal precautions