The Human Lung Fluke – Paragonimus Westermani (Domain Eukarya, Kingdom Animalia, Phylum Plathyhelminthes, Class Trematoda)

Title: The Human Lung Fluke – Paragonimus Westermani (Domain Eukarya, Kingdom Animalia, Phylum Plathyhelminthes, Class Trematoda)

Author: Kughan Govinden

Affiliation: 2nd Year Medical Student of Nizhny Novgorod State Medical Academy, Russia, Public Service Department Scholarship Holder, active member of International Physicians for Preventing Nuclear War(IPPNW), Global Youth Coalition Against AIDS (GYCA) and virtual volunteer of TakingITGlobal.

Object of Investigation: Biological slide of Paragonimus Westermani  

Aim: To investigate and provide brief information about classification, morphology, epidemiology, life cycle, laboratory diagnosis, prevention and prophylaxis of Paragonimus Westermani.

Introduction and distribution: Paragonimus westermani is the best known of the lung flukes affecting humans (in addition to zoonotic infections in cats, dogs, pigs and a large number of other animals) and that with the widest geographic range.  However, the genus includes a large number of species, all of which also appear to b e capable of infecting man as well. These include; P.Kellicotti, P.Africanus, P.Uterobilateralis, P.Ohirai, P.Iloktsuensis, P.Caliensis, P.Peruvianus, P.Mexicanus and many others. It also behaves in humans much as in its feline and other wild hosts and we can assume that the host-parasite relationship is good. P.westermani is a common human parasite in the Far East, including Japan, Korea, Manchuria, the People’s Republic of China (including Taiwan), Southeast Asia and Papua New Guinea. In the Pacific area, it is found in the Solomons and Samoa. In the Indian subcontinent, it occurs in Bengal, Madras, Manipur, Assam, the area around Bombay and in Sri Lanka. In Africa, it has been reported from the Congo, Nigeria, and the Cameroon.

Morphology: This fluke is reddish-brown in colour, oval in shape and measures 8-16mm in length and 4-8mm in width. It’s tegument is covered in many small spines. The suckers are approximately the same in size, the ventral sucker being slightly anterior to the midline of the parasite. The bifurcated gut is not branched. For the sexual organs, the testes are lobed and are parallel in the posterior portion of the body whilst the ovary is also lobed and is located above the testis, usually on the right hand side of the body, opposite a tightly coiled uterus. The vitellaria are located laterally, running from the anterior to the posterior side of the parasite.

Epidemiology:  In some areas, human paragonimiasis may be common enough that human-to-human transmission (via the appropriate snail and crab intermediate host) occurs. In most areas the disease is principally one of the local crab-eating mammals and humans enter into the lifecycle accidentally. Many different species of crabs and crayfish may be infected in various parts of the world and only seldom are these parts of human diet. Thus, endemicity of the disease rests on dietary habits, methods of food preparation