2. Trypanosomoses, dourine, Leishmaniosis, Giardiosis, Bovine and avian trichomonisis, Histomonosis, Entamoebosis

Question 1

Trypanosomosis

• general morphologu
• transmission

Answer 1

General morphology of trypanosomes:

• monomorphic (T. vivax, T. congolense) or pleomorphic (T. brucei)
• 10-40 μm length, large nucleus, kinetoplast, flagellum – undulating membrane
• forms: trypomastigote (metacyclic form - infective stage), epimastigote, promastigote, amastigote

Transmission of trypanosomes:

• cyclic: an arthropod vector is a necessary biological vector in which they multiply and infective stage develops e.g. T. brucei – Glossina spp.
• non-cyclic: only mechanical transmission by an arthropod vector e.g. T. evansi – S. calcitrans

Question 2

Dourine

Answer 2

- “Trypanosoma equiperdum” (genetic variants of T. brucei evansi and T. brucei equiperdum)

History (Anamnesis): horse and donkey; venereal disease

Clinical signs:

• genitals: inflammation and ulceration of the genital mucous membranes, oedema (ventral abdominal too), hypopigmentation of skin
• skin: “dollar spots” - transient urticaria (2-5 cm in diameter) on withers, thorax, neck, etc.; they are neither warm nor painful
• nerves: hyperaesthesia, anaesthesia, ascending motor paralysis

Parasitological diagnosis

• sampling: peripherial blood sample; scraping of the genital mucous membrane (in fresh cases); puncture of dollar spots
• in parasitaemia - motile trypanosomes (trypomastigotes) in fresh films of blood: centrifugation of the blood sample in microhaematocrit tube may help to find them → miscroscopic examination of the interface between the buffy coat and the plasma.
• Giemsa staining of thick or thin smears of blood – scarcity of trypanosomes in the blood
• serological methods – Complement Fixation Test 2x with 3 weeks intervals

Necroscopy findings – not characteristic

Question 3

Nagana

Answer 3

– T. vivax, T. congolense, T. brucei brucei

History: horses, cattle, camel, etc.; in tropical part of Africa

Clinical signs: lymphoid enlargement and splenomegaly

• anaemia – cardinal in cattle
• cell degeneration and inflammatory infiltrates in many organs (CNS, skeletal muscle) - in horse (T. brucei brucei): oedema of the limbs and genitalia
• in dog and cat (T. brucei and T. congolense): anaemia, myocarditis, ataxia, convulsions

Parasitological diagnosis

• sample from peripherial blood/lymph nodes – staining and examination with dark ground/phase contrast microscopy for detecting trypomastigotes
• in parasitaemia - motile trypanosomes in fresh films of blood - centrifugation of the blood sample in microhaematocrit tube may help to find them → microscopic examination of the interface between the buffy coat and the plasma
• serological methods

Necroscopy findings – not characteristic

Question 4

Surra

Answer 4

– T. brucei evansi (in South-America: mal de caderas = “disease of the hip”)

History: camel, horse, dog, ruminants, etc.

Clinical signs

• not characteristic, e.g. fever, lymphadenopathy, abortion
• oedema (genitalia/ventral abdomen), (posterior) paralysis in the horse
• oedema, haemorrhages, ocular signs in the dog

Parasitological diagnosis: Giemsa staining of smears of blood for detecting trypomastigote, serology

Necroscopy findings – not characteristic

Question 5

Leishmaniosis

Answer 5

Leishmania tropica, L. infantum, L. donovani, L. chagasi - Zoonosis!

History: man, dog, cat (rarely); in tropical and subtropical regions

Clinical signs:

• cutan form (more common in dog): alopecia, dermatitis, ulceration of the skin
• visceral form in dog: intermittent fever, enlargement of lymph nodes, spleen, liver; cachexy, anaemia, diarrhoea, ataxia

Parasitological diagnosis:

• demonstration of the amastigote form in smears or scrapings (intracellular, 2-4 μm parasites in macrophages)
• biopsy of lymph nodes, liver, spleen, marrow or skin – Giemsa staining
• serological methods
• PCR technique

Necroscopy findings – not characteristic

Question 6

Giardiosis

Answer 6

Giardiosis – Giardia duodenalis - Zoonosis!

History: man, young animals (mammals and birds), mainly dog

Clinical signs:

• usually symptomless
• young dogs may show malabsorption syndrome and pancreatic insufficiency
• emaciation or poor growth is seen despite a normal appetite
• persistent mucous, yellow and slimy diarrhoea, loss of appetite, vomiting, abdominal pain

Parasitological diagnosis

• direct examination (high magnification of 400X) of fresh faecal smear mixed with a drop of physiological saline and Lugol solution for the detection of moving trophozoites (vegetative form) – 10-20 μm, pear shaped, symmetrical, two nuclei, two axostyles, four pairs of flagella with jerky shuffling movements like dead leaves in the wind
• thin faecal smear stained with Giemsa
• flotation (ZnSO4) for concentration of cysts (infectious form) – 9-15 μm, oval, four nuclei
• immunological methods for the detection of Giardia antigens in the faeces

Necroscopy findings – not characteristic

Question 7

Trichomonosis of cattle

Answer 7

Tritrichomonas foetus

History: cattle, insemination with bulls

Clinical signs

• in bulls: inapparent, rarely inflammation of mucous membranes of preputium, urethral discharge
• in cows/heifers: vestibulitis, vaginitis, ascending endometritis, pyometra, vaginal disharge. Early abortion (before 4th month) – this is often undetected because of the small size of the foetus. Anoestrus - extended calving intervals

Parasitological diagnosis:

• washing of the preputium with physiological saline or special solution; collecting of vaginal/uteral discharge; seminal fluids (keeping for 6 hours at 37 ˚C) – centrifugation and direct examination of sediment within 12 hours
• culturing at 37 ˚C
• Giemsa staining – pear-like, one flagellum forming undulating membrane running backwards, three flagella running forward
• serological methods – not very sensitive
• PCR technique

Necroscopy findings – greyish yellow papules on the chorion of the foetus

Question 8

Trichomonosis of birds

Answer 8

Thrichomonas gallinae

History: young pigeons, occasionally in turkeys, chickens, other birds

Clinical signs:

• foul odour from the mouth, pendulous crop
• visible yellowish pseudomembrane, necrotic lesions in the mouth and in the pharynx
• apathy, diarrhoea, suffocation, cachexy

Parasitological diagnosis

• a smear from crop or oesophageal lesions – add one drop of physiological saline – examinantion with dark ground/phase contrast microscope
• in fresh sample vividly moving organisms: lemon shaped, 6-18 μm length with one flagellum forming an undulating membrane running backwards and four flagella running forward

Necroscopy findings

– yellowish diphtheritic membrane in the mouth, pharynx, oesophagus, proventriculus, crop

– necrotic lesions in the liver – hepatic form

– necrotic lesions in the liver, heart and air sacs – generalized form

Question 9

Histomonosis

Answer 9

(“blackhead”, infectious enterohepatitis) – Histomonas meleagridis

History: young turkeys (up to 14 weeks old), chickens, guinea fowl, pheasant, etc.; Heterakis infection

Clinical signs

• loss of appetite, diarrhoea, yellow faeces
• “blackhead”: misnomer (cyanosis of head, comb and wattle almost never observed)

Parasitological diagnosis

• smears from the edge of the lesions - add one drop of physiological saline – examination with dark ground/phase contrast microscope
• in vitro breeding of parasites from fresh carcass
• PAS positivity and Gram negativity in histological sections
• flagellate form (10-20, max. 30 μm, round or ovoid with one flagellum) in caecal lumen
• amoeboid form (8-15 μm, round without flagellum) in tissues - pleomorphic

Detection of the parasites is difficult!

Necroscopy findings

• yellowish, necrotic, caseous material in the lumen of caecum, its wall thicked, pinpoint ulcers in the wall
• deep, circular, crateriform necrotic foci (0.5-2.0 cm in diameter) with sharp edges in the liver, dry cut surface
• necrotic lesions in spleen, lung and kidneys too, wet cut surface of liver - generalized form in guinea fowl

Question 10

Entamoebosis

Answer 10

Entamoebosis – Entamoeba histolytica - Anthropozoonosis!

History: man, monkey, young dog, rarely kitten

Clinical signs

• bloody and mucous diarrhoea, fever, digestion problems, abdominal pain, exsiccosis

Parasitological diagnosis

• direct examination of fresh faecal smear mixed with a drop of physiological saline and Lugol solution for the detection of moving trophozoites (vegetative form) – 10-20 μm, irregular shape, vesicle-like nucleus
• flotation (Zn SO4) for concentration of cysts (infectious form) – 10-15 μm, round, four nuclei - No cysts in faeces of animals!
• immunological methods for the detection of Entamoeba antigens in the faeces

Necroscopy findings – not characteristic