Dwarf tapeworm nanos means dwarf, up to 40 mm long. This cestode belongs to a large family known as hymenolepididae. Hymenolepis diminuta are greater than 30 cm in length and hymenolepis nana are less than 6 cm in length. Description of hymenolepis microstoma nottingham strain.
Pdf malignant transformation of hymenolepis nana in a. Pdf malignant transformation of hymenolepis nana in a human. Himenolepiasis parasitologia medica, 4e accessmedicina. It is often referred to as the dwarf tapeworm due to its small size, 24 cm long and only 1 mm wide. Hymenolepis diminuta rodolphi, 1819 infection in a child from iran. The authors cite some ear lier cases as examples of proliferating.
Alternative names are dwarf tapeworm infection and rat tapeworm infection. The immune response to hymenolepis nana in mice decreases. The hymenolepis nana commonly known as the dwarf tapeworm and the hymenolepis diminuta commonly known as the rat tapeworm. Rodents are the primary definitive hosts, and grain beetles, fleas, or other insects feed on contaminated rodent droppings as intermediate. The dwarf tapeworm was found in man for the first time by bilharz, in cairo, egypt, in 1851. When eggs are ingested by an arthropod intermediate host various. The dwarf tapeworm, or hymenolepis nana, is the most common tapeworm in humans. The disease is a type of helminthiasis which is classified as a neglected tropical disease.
Nov 04, 2015 the dwarf tapeworm, or hymenolepis nana, is the most common tapeworm in humans. A polymerasechainreaction pcr assay targeting eukaryotes identified hymenolepis nana dna. Hymenolepis nana has been called the dwarf tapeworm and has a worldwide distribution. Although the transmission of cancer is a surprising event, this is. Invasion of human tissue by abnormal, proliferating, genetically.
Hymenolepis nana is a human tapeworm that can complete its life cycle in the small intestine. Apr 20, 2015 hymenolepiasis is the most common intestinal tapeworm infection of humans caused by worm of family cestoda, genus hymenolepis and species nana. Drugs used to treat dwarf tapeworm infection hymenolepis nana the following list of medications are in some way related to, or used in the treatment of this. This infection does not require an intermediate host and infection can occur directly from one. Nov 05, 2015 the morphologic features and invasive behavior of the cells were characteristic of cancer, but their small size suggested a nonhuman origin. Although other methods are available that can be used to distinguish hymenolepis diminuta from hymenolepis nana, an evaluation of adult size is the most convenient, not requiring specialized training for evaluation of the morphology of.
The dwarf tapeworm, hymenolepis nana, cancer cells linked. The worms mature into a life form referred to as a cysticercoid in the insect. When eggs are ingested by an arthropod intermediate host various species of beetles and fleas may serve as intermediate hosts, they develop into cysticercoids, which can infect humans or rodents upon. The dwarf tapeworm, hymenolepis nana, cancer cells linked to. N engl j med 2015 nov 4 malignant transformation of h. He recovered a countless number of them at a postmortem on a boy who had died of meningitis. It is the first known case of a person becoming ill from cancer cells that arose in a parasite in this case, hymenolepis nana, the dwarf tapeworm. Praziquantel, adults and children, 25mgkg in a singledose therapy alternatives. Although the cells were unrecognizable as tapeworm tissue, immunohistochemical staining and probe hybridization labeled the cells in situ. The infiltrate around the tumor was composed mainly of eosinophils and neutrophils. Malignant transformation of hymenolepis nana in a human host article pdf available in new england journal of medicine 37319.
The adult tapeworm parasitizes the small intestine of. Hymenolepiasis is the term when a human is infected with either h. Hymenolepis microstoma dujardin, 1845 blanchard, 1891, the mouse bile duct tapeworm, is a rodentbeetlehosted laboratory model that has been used in research and teaching since its domestication in the 1950s. Hymenolepiasis is prevalent throughout the world with human infections with h.
On the inner membrane are two poles, from which 4 to 8 polar filaments spread out between the two membranes. Hymenolepis nana, a tiny intestinal tapeworm, is the most common human cestode. During the course of a survey on the intestinal protozoan infections among 362 children in st. It is also known as the dwarf tapeworm due to its particularly small size adults are only 1540 mm long. Tsuchiya, three cases of infection with hymenolepis nana were incidentally encountered. Hymenolepis nana dwarf tapeworm parasites in humans. Later, morphological characteristics were used for taxonomy identification and h. Tumours consisting of tapeworm cancer cells found in human. In human adults, the tapeworm is more of a nuisance than a health problem, but in small children, many h. Hymenolepis diminuta infection infectious diseases msd. Hymenolepis nana is the most common cestode parasite of humans in the world roberts and janovy, 2000. Hymenolepis nana has a worldwide distribution with estimates of 5075 million carriers.
What is hymenolepis nana infection the dwarf tapeworm or hymenolepis nana is found worldwide. Hymenolepis nana dwarf tapeworm infection infectious. It is the smallest and only cestode that parasites the human without any intermediate host. Hymenolepis rodentolepis nana is the most common cestode of humans, particularly in young children. Diplacanthus manus, hymenolepis nana, hymenolepis murina. Hymenolepiasis is infestation by one of two species of tapeworm.
This parasitic worm is most frequently passed on through eggs in the faeces of another. Malignant transformation of hymenolepis nana in a human host. Clinicopathological studies on spontaneous hymenolepis. It is small and measures up to 2540 mm in length by one mm in diameter.
Nov 04, 2015 invasion of human tissue by cancer like hymenolepis nana cells larry m. Hymenolepiasis is the most common intestinal tapeworm infection of humans caused by worm of family cestoda, genus hymenolepis and species nana. Hymenolepis nana, the dwarf or dwarf mouse tapeworm, is a small tapeworm in humans, sometimes found in great numbers in the intestine. In this study we examined the intestinal mucosa of an adult asymptomatic patient harboring adult and larval dwarf tapeworms hymenolepis nana who. It is the only cestode that does not require an intermediate host to develop into its infective stage. Cdc hymenolepis resources for health professionals. Hymenolepis diminuta infection in a child living in the urban area of rome, italy. Eggs hatch in the duodenum, releasing oncospheres, which penetrate the mucosa and come to lie in lymph channels of the villi. Jcm free fulltext production and use of hymenolepis. Larval and adult beetles but optional larval stage, cysticercoid, can develop. Hymenolepis nana infection is observed in households with poor hygiene and overcrowding, and can have a prevalence of 525% in children 54. Hymenolepiasis is primarily caused by the cestode tapeworm species, hymenolepis nana the dwarf tapeworm, adults measuring 15 to 40 mm in length. Human infection is usually asymptomatic, it but can cause mild gastrointestinal symptoms. It lodges itself in the intestines and absorbs nutrients from the intestinal lumen cameron, 1956.
Given the widespread distribution and medical implication of members of the genus hymenolepis, specific identification of the aetiological agent becomes imperative. The species name nana is derived from its small size which means dwarf of the adult worm. For precise diagnosis of the species, molecular techniques such as pcr and rflp of. Original article from the new england journal of medicine malignant transformation of hymenolepis nana in a human host. Its larvae migrate only within the gut wall, and its life span is relatively short 4 to 6 weeks.
The fact that an intermediate host is not required in the life cycle was determined in the late 1800s. Infection is most common in children, in persons living in institutional settings, and in people who live in areas where sanitation and personal hygiene is inadequate. Areas of endemicity up to 26% prevalence include asia, southern and eastern europe. Larval and adult beetles but optional larval stage, cysticercoid, can develop in d. Hymenolepis nana, also known as dwarf tapeworm, is a cyclophyllidean tapeworm with embryonated eggs. Causal agent, life cycle, and geographic distribution. Hymenolepis nana human diagnosed through colonoscopy. Humans, rodents most common tapeworm of humans in the world 1% rate of infection in the southern u.
In 1906, stiles identified an identical parasite with a rodent host and named it hymenolepis fraterna. Invasion of human tissue by cancerlike hymenolepis nana cells. Cancer is a highimpact disease throughout the world. Hymenolepis nana infestation is commonly diagnosed in. Courtesy peter olson, natural history museum, london hide. Eggs of hymenolepis nana are immediately infective when passed with the stool and cannot survive more than 10 days in the external environment. It requires only one host but can also cycle through two. It is often referred to as the dwarf tapeworm due to its small size, 24 cm long and only 1 mm wide 1 fig. The morphologic features and invasive behavior of the cells were characteristic of cancer, but their small size suggested a nonhuman origin. Its larvae migrate only within the gut wall, and its life span is relatively short 4 to 6 wk. Hymenolepis nana, the dwarf tapeworm, is the smallest tapeworm to infect humans. Hymenolepiasis is an infection caused by hymenolepis nana h.
Malignant transformation of hymenolepis nana in a human host to the editor. Parasitic dna was sequenced to identify the tapeworm species. Humans and other animals become infected when they intentionally or unintentionally eat. In the southeastern usa, as many as 1% of young schoolchildren. Hymenolepis nana bilharz, 1851 ransom, 1901 1 dwarf tapeworm hymenolepis nana, also known as rodentolepis nana, vampirolepis nana, hymenolepis fraterna, and taenia nana is a cosmopolitan species though most common in temperate zones, and is one of the most common cestodes a type of intestinal worm or helminth infecting humans. Although the cells were unrecognizable as tapeworm tissue, immunohistochemical staining and probe hybridization.
Routine histology and immunohistochemistry were performed to characterize the hosts response to the parasite. Hymenolepiasis is an intestinal infection by one of two specific types of the following hymenolepis species of tapeworm parasite. Hymenolepis worms live in the intestines of rats and are common in warm climates, and are generally found in the feces of rats, which are consumed by their secondary hostsbeetles. The adult worm resides in the ileal portion of the small intestine. Hymenolepis nana is the most common tapeworm in humans. Development hymenolepis nana life cycle infection is acquired most commonly from eggs in the feces of another infected individual, which are transferred in food, by contamination. Hymenolepis diminuta is a tapeworm that can cause intestinal infection in humans. Hymenolepis nana is the smallest of all tapeworms found in humans and is appropriately described as the dwarf tapeworm. In this article we will discuss about hymenolepis nana. Malignant transformation of hymenolepis nana in a human. Hymenolepis nana is also known as the dwarf tapeworm.