PLATYHELMINTHES

Vesselin Alexandrov, PhD Department of Languages and Specialized Training 1 TAXONOMY

 Class Turbellaria – Cilliated worms free living worms, 4500 species  Class (Trematodes) – Flukes endoparasites, 11000 species  Class (Cestoidea) – Tapeworms endoparasites, 3400 species  Class Monogenea – Monogeneans fish ectoparasites, 1100 species

2 WORLD DISTRIBUTION

Free living worms in oceans, seas, freshwater lakes and rivers, and wet habitats

Endoparasites in almost all vertebrates

Ectoparasites, especially on the fish gills

3 Trematoda - Flukes

4 Тrematoda – Flukes Morphology  Entirely parasitic life  Endoparasites  Biohelminths  Body  Flat, unsegmented, leaf shaped (mostly)  Covered by integument, three layers of muscles under it  Dimensions: from several mm to 10 cm  Oral sucker – for feeding and attachment  Ventral sucker – for attachment

5 Тrematoda – Flukes Morphology  Digestive system: one opening, muscle gullet (mostly), esophagus, two blind gut branches, no anus  Nervous system: ganglion type, pharyngeal ganglion (nervous ganglion ring), two longitudinal nerve cords. No sensory organs  Excretory system: protonephridial type, two collecting excretory channels, excretory bladder  No respiratory and circulation system: diffusion through all the body surface  Reproductive system: hermaphrodites (mostly), allogamy (cross-fertilization)  Eggs: ovoid, some of them with operculum

6 Trematoda – reproductive system Hermaphrodites

7 Trematoda – reproductive system

8 Main fluke types  Hermaphrodites:  flukes:  (South-East Asia, China, India)  (cosmopolitan)  Fasciola gigantica (up to 10 cm) (Egypt, Tropics)  Intestinal flukes:  buskii (China, South-East Asia)  Lung flukes:  (South-East Asia, China, India)  Paragonimus mexicanus (South America)  Sexually differentiated:  Blood flukes:  Schistosoma haematobium (Egypt, West Asia)  (Africa, South America, Caribbean)  Schistosoma japonicum (Far East, Japan, China, Philippines)

9 Liver flukes - morphology  Fasciola hepatica (Sheep )  Size: 3-5 cm  Pumpkin seed shaped  Organs with tree-like embranchment  (Lancet liver fluke)  Size: 6-10 mm  Leaf shaped, sharp conical anterior end, round posterior end  Blind ended guts, no branches  Ovoid ovary and testes, testes at anterior end, uterus at posterior end  Opistorchis felineus (Cat liver fluke)  Size: 8-13 mm  Shape: leaf shaped, sharp anteriorly, round posteriorly  Testes at the posterior end, uterus at the anterior end

10 Trematoda operculated eggs

11 Fasciola hepatica (Sheep liver fluke) Life cycle

12 Fasciola hepatica (Sheep liver fluke) intermediate hosts

Lymnaea stagnalis Lymnaea truncatula

13 Fasciola hepatica (Sheep liver fluke) Developmental stages  Miracidium  Cercaria

 Metacercaria  Redia

14 Fasciola hepatica (Sheep liver fluke)  Pathogenicity:  Mechanical damage of bile duct and liver, sometimes diaphragm and lungs  Secondary bacterial  Nutrition and toxic effects  Clinical symptoms:  Fever, nausea, pain in the right upper abdominal part  Hepatomegaly  Allergic reactions  Diagnostics  Fecal helminth ovoscopy – eggs in the feces

15 F. hepatica in a child eye

16 Dicrocoelium dendriticum (Lancet liver fluke) – life cycle

17 Dicrocoelium dendriticum (Lancet liver fluke) - intermediate hosts

Zebrina sp. Helicella sp. Formica sp.

18 Dicrocoelium dendriticum Lancet liver fluke  Pathogenesis  Mechanical damages of the bile and liver duct wall  Secondary bacterial  Toxic effects  Clinical features  The massive invasion causes heavy injuries of liver parenchymal tissue  Hepatic  Bile duct obstruction  Diagnostics  Helminth ovoscopy:  eggs in stools or in the duodenal juice

19 felineus (Cat liver fluke) life cycle

20 Opisthorchis felineus (Cat liver fluke) hosts

Scardinius Barbus barbus erythrophthalmus (barbel) (rudd)

Leuciscus cephalus Tinca tinca (chub) (, doctor fish)

Bithynia leachii Cyprinus carpio Esox lucius (carp) (Northern pike)

21 Opisthorchis felineus (Cat liver fluke)  Pathogenesis  Pancreatic or hepatic injuries  Inflammation of bile duct  Secondary bacterial infection  Clinical features  Pain in the right upper abdominal part, chills, nausea, vomiting  Allergic reactions  Liver enlargement and Opisthorchis felineus tenderness, cirrhosis on a late in tissue cross sections stage  Diagnostics  Helminth ovoscopy:  eggs in stools or in the duodenal juice

22 Blood flukes (Schistosoma sp.) – morphology and differences

 Diecious. Sexually differentiated  Male – short and thick, up to 15 mm, gynecophoric canal  Female – thin and long, up to 26 mm, fits into the gynecophoric canal  Lack of muscular pharynx  Both of the intestines reunite after bifurcation and form a single canal  The eggs are non-operculated  No redia and metacercaria stage  Cercariae have a forked tail and actively penetrate the ’s skin

23 Trematoda stages comparison

24 Schistosoma eggs – non-operculated Schistosoma – life cycle

26 Schistosoma (S. japonicum, S. mansoni, S. haematobium) – intermediate hosts

Oncomelania sp. Bulinus sp. Australorbis sp. (Biomphalaria sp.) 27 Miracidium – ciliated and motile form

28 Cercaria with a forked tail

29 Cercaria with a forked tail

30 Cercaria with a forked tail

31 Cercaria with a forked tail

32 Schistosoma mansoni Schistosoma mansoni - male

34 – the second world distributed

35 Schistosomiasis – World distribution

36 Schistosomiasis  Pathogenesis and clinical features  Swimmer’s itch – after skin penetration  Cercarial dermatitis and lesions at the site of entry  Anaphylactic and toxic symptoms (fever, headache, urticaria)  Enlarged liver, palpable spleen  Egg deposition  Painless hematuria  Hyperplasia and inflammation of bladder and intestinal mucosa  Chronic stage and tissue proliferation  Chronic cystitis  Generalized hyperplasia and fibrosis of vesical and intestinal mucosa  Pseudoabscesses due to infiltration of lymphocytes, plasma cells, eosinophils at the site of egg deposition  Caliculi in the bladder due to oxalate deposition and uric acid crystals  Carcinoma of the bladder and the large intestine  Diagnostics  Eggs in stools and urine  Immunology tests

37 Hystopathological tissue cross section of urinary bladder with eggs of Schistosoma haematobium,

Schistosoma eggs and adult worms in lung tissue

38 Swimmer’s itch

39 Tortuous Varicosities in Chronic Schistosomiasis

40 Way of schistosomiasis distribution

41 Ernst Haeckel's “Kunstformen der Natur” or “Art forms of nature”

42