Session 16: Diphyllobothrium latum & Dipylidium caninum PDF

SESSION 16: Diphyllobothrium latum Broad/fish tapeworm By Mwamkoa, MJ 1  Introduction Diphyllobothrium is a genus of tapeworm which can cause Diphyllobothriasis in humans through consumption of ra...

SESSION 16: Diphyllobothrium latum Broad/fish tapeworm By Mwamkoa, MJ 1  Introduction Diphyllobothrium is a genus of tapeworm which can cause Diphyllobothriasis in humans through consumption of raw or undercooked fish. The principal species causing diphyllobothriasis is Diphyllobothrium latum, known as the broad or fish tapeworm 2  Definition of Terms Diphyllobothriasis - infection with the cestode Diphyllobothrium latum; human infection is caused by ingestion of raw or inadequately cooked fish infected with the plerocercoid larva. Coracidium - a ciliated first-stage larval stage in the egg of pseudophyllid and other cestodes with aquatic life cycles. 3  Definition of Terms… Procercoid - a tailed first stage, newly hatched larva in the body cavity of the crustacean the first intermediate host. Plerocercoid - a wormlike nonsegmented larva with an invaginated scolex at one end, which develops in an animal serving as the second intermediate host. e.g. fish, reptiles, or amphibians. 4  Epidemiology & Geographical Distribution Mostly seen in areas where: Fish is commonly eaten and sanitation is sub-standard Co-habitation of fish-eating animals like bears, canids, felines, pinnipeds, and mustelids and humans and on presence of intermediate hosts Cultures of eating raw and/or under-cooked fish increase the risk It occurs in the Northern Hemisphere (Europe, newly independent states of the former Soviet Union [NIS], North America, Asia), Japan and in Uganda and Chile. 5  Geographical Distribution Freshwater fish infected with Diphyllobothrium sp. larva may be transported to and consumed in geographic areas where active transmission does not occur, resulting in human diphyllobothriasis. For example, cases of D. latum infection associated with consumption of imported fish have been reported in Brazil. 6  Transmission Transmission is principally through: Ingestion of raw/undercooked infected fresh water fish, in whose muscles plerocercoid larval stage are found trapped. Accidental ingestion of larval stages found on hands of fish processors and cleaners. Fish act as 2nd intermediate hosts of the parasite, humans are implicated to maintenance of the parasite in communities (where intermediate hosts are available). Other (fish-eating) animals are also affected. 7  Clinical feature & Pathology Symptoms are generally mild, and can include diarrhoea, abdominal pain, vomiting, weight loss, fatigue, constipation and discomfort. Symptoms are the result of body reaction to foreign waste, proglottids and irritation on attachment site. Approximately four out of five cases are asymptomatic and may go many years without being detected. Usually due to size, a human is infected by a single worm At times mild symptoms may be presented, which are normally vague: Obstruction, abdominal discomfort and pain, weight loss and malabsorption. 8  Diseases caused by D. latum In a small number of cases, this leads to severe vitamin B12 deficiency due to the parasite absorbing 80% or more of the host’s B12 intake which helps in synthesis of hemoglobin, this leads to a megaloblastic anaemia indistinguishable from pernicious anaemia. The anaemia can also lead to subtle demyelinative neurological symptoms (sub acute combined degeneration of spinal cord). Infection for many years is required to deplete the human body of vitamin B12 to the point that neurological symptoms appear. 9  Diagnosis Depends on parasitological finding of: Eggs in feces Occasionally proglottids can be demonstrated in feces However, when the species needs to be determined (in epidemiological studies, for example), restriction fragment length polymorphisms can be effectively used. PCR can be performed on samples of purified eggs, or native faecal samples following sonication of the eggs to release their contents 10 11  Treatment Praziquantel & niclosamide are drugs of choice B12 supplement. 12  Prevention and Control Avoid consumption of raw or poorly cooked infected fish. Screening and successful treatment of people infected with the parasite Proper sewage disposal to prevent fecal-water contact Health education about Proper preparation of fish by thorughly cooking Prevention water contamination by raising public awareness of the dangers of defecating in recreational bodies of water and by implementation of basic sanitation measures Frozen fish at -10°C for 24–48 hours to kill plerocercoid larva. 13  Dipylidium caninum (Double pore tapeworm)  Introduction Dipylidium caninum is a dog and cat tapeworm, also called the cucumber tapeworm or the double-pore tapeworm. The proglottids have two genital pores; one on each side of the proglottid. Each side has a set of male and female reproductive organs. The presence of these bilateral genital pores is a key diagnostic feature.  Introduction… Dipylidium caninum is a Cyclophyllidea Cestoda that infects organisms affiliated with fleas, occasionally found in children due to close contact with their infected pets.  Geographical Distribution Has Worldwide distribution. Human infections have been reported in Europe, the Philippines, China, Japan, Argentina, and the United States.  Habitat Adult: Reside in the small intestine of the host, where they each attach by their scolex. Ploglottids can be found in the perianal region, in the feces, on diapers, and occasionally on floor covering and furniture. The proglottids are motile when freshly passed and may be mistaken for maggots or fly larvae.  Habitat Eggs: Are found in the host's faeces and/or ingested by fleas. Larvae: Found in the flea's intestine  Transmission Gravid proglottids are passed intact in the feces or emerge from the perianal region of the host. Subsequently they release typical egg packets. Following ingestion of an egg by the intermediate host (larval stages of the dog or cat flea Ctenocephalides spp.), an oncosphere is released into the flea's intestine.  Transmission… The oncosphere develops into a cysticercoid larva in the intestinal wall of the fleas. Humans and other vertebrate hosts becomes infected by ingesting the adult flea containing the cysticercoid. The dog is the principal definitive host for D. caninum. Other potential hosts include cats, foxes, and humans (mostly children).  The diseases caused by D. caninum Most infections with Dipylidium caninum are asymptomatic. Pets may exhibit behaviour to relieve anal pruritus (such as scraping anal region across grass or carpeting). Mild gastrointestinal disturbances may occur. Passage of proglottids is the most striking feature in animals and children. The proglottids are motile when freshly passed and may be mistaken for maggots or fly larvae.  Prevention and control Adequate use of latrine or toilet. Spraying insecticide to kill fleas in domesticated animals Early diagnosis and treating of infected individual Regular deworming of domestic animals and humans. Avoid handling of dogs unnecessary  Laboratory diagnosis The diagnosis is made by; Macroscopic demonstration of the typical proglottids in the stool or the environment Microscopic demonstration of eggs or egg packets in the stool. Morphologic comparison with other intestinal parasites.