Veterinary Helminthology

• Crustacea-Borne Parasitic Zoonoses:
• Angiostrongylus cantonensis (Rat lungworm): Uses freshwater prawns and crabs as paratenic/intermediate hosts.
• Dracunculus medinensis (Guinea worm): Uses copepod crustaceans (Cyclops) as intermediate hosts.
• Paragonimus westermanii (Lung fluke): Uses freshwater crabs and crayfish as second intermediate hosts.
• Opisthorchis tenuicollis (Opisthorchis felineus / Cat liver fluke):
• First intermediate host: Freshwater snail (Bithynia).
• Second intermediate host: Cyprinid freshwater fishes (encysts as metacercariae in fish flesh), NOT crustaceans.
• nalysis:
• (Opisthorchis tenuicollis): Correct (fish-borne, not crustacean-borne).

Correct option: (4) Opisthorchis tenuicollis

• Etiology of Human Visceral Pentastomosis: Visceral pentastomosis in humans is caused by the nymphal stage of Armillifer armillatus (and Armillifer grandis), parasitic tongue worms inhabiting the respiratory tract of large African and Asian snakes (pythons, vipers).
• Transmission Routes:
• Ingestion of drinking water contaminated with eggs shed in snake secretions or faeces [Statement A is TRUE].
• Direct intimate contact with reptile skins/carcasses during slaughter or consumption of poorly cooked snake meat [Statement B is TRUE].
• Contrasting Condition (Halzoun/Marrara): Ingestion of raw liver/lymph nodes of sheep/goats containing nymphal Linguatula serrata causes nasopharyngeal pentastomosis (Halzoun syndrome), where nymphs attach to the pharynx and soft palate rather than causing visceral encystment.

Correct option: (3) (A) and (B) only.

• Substituted Phenols in Veterinary Medicine:
• Substituted phenolic anthelmintics act by uncoupling oxidative phosphorylation in helminth mitochondria:
• Bithionol: Dichlorophenolic compound.
• Hexachlorophene: Bisphenol derivative.
• Nitroxynil: Substituted monophenol ($4\text{-hydroxy-3-iodo-5-nitrobenzonitrile}$).
• Niclosamide:
• chlorinated Salicylanilide derivative (5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide), not classified chemically as a simple substituted phenol.
• nalysis:
• (Niclosamide): Correct.

Correct option: (3) Niclosamide