Uncommon
cestodes
Bertiella
species
Bertiella is a genus of tapeworm in the family Anoplocephalidae, many species of which
exist as parasites of nonhuman primates. Two species of the genus, Bertiella studeri and B. mucronata, can infect humans.
The origin of infection was not
confirmed; the only clue was that the boy's parents had once raised tame
monkeys in a zoo. When the boy was 2 years old, he often played in the
wildland, which is part of the zoo near the forest, and frequently fed and
played with the captured monkeys. Further questioning showed that the boy had
also been in frequent contact with wild monkeys. It was not confirm whether he
had been infected by eating monkey food contaminated with mites. More than 50
cases of human infection have been recorded, and the geographic distribution of
cases shows that the tapeworm exists in countries in Asia, Africa, and the
Americas. Animal infection has been recorded in some provinces in China, and
human bertiellosis has been recorded in Sri Lanka, Saudi Arabia, Vietnam,
Japan, India, Thailand, Malaysia, and other Asian countries.
Life cycle
The lifecycle of the cestode requires
2 hosts; nonhuman primates are generally the final host, while oribatid mites
are the intermediate host, in which the infective cysticercoid of the cestode
develops. Orbatid mites may exist in soil to maintain natural infection, and
the definitive host is infected by eating or otherwise coming into contact with
contaminated soil or food. The definitive hosts become infected after ingesting
arthropod intermediate hosts infected with cysticercoids. Adults reside in the small
intestine of the definitive host where they attach to the mucosa with the aid
of an unarmed scolex. Eggs and proglottids are passed in the feces of the
definitive host. Oncospheres are ingested by the arthropod intermediate host.
This host in nature is believed to be one or several species of oribatid mites.
In the arthropod intermediate host, the oncospheres develop into
cysticercoid. Although rare, humans may
also serve as definitive hosts for Bertiella spp., usually after accidentally
ingesting infected mites. Most human cases of bertiellosis are in patients who
had some level of contact with primates.
Clinical manifestation
Patients are usually asymptomatic but nausea, diarrhoea, anorexia and
abdominal pain sometimes occur.
Laboratory Diagnosis
Diagnosis
is made by the finding of motile
proglottids or, less-commonly, eggs in stool. The eggs are characteristics and
can be liberated from gravid proglottids. Ova can be seen in the deposit of a formalin
ether/acetate concentration of the stool.
Treatment
Various medications have been used with
anecdotal success for treatment of individual patients. One such medication is
praziaquantel, which is commonly used to treat infections with other intestinal
tapeworms.
Prevention and control
To prevent human bertiellosis, the
relationship between human cases and the natural host must be investigated.
Diplogonoporus grandis
Diplogonoporus
grandis is one of human broad tapeworms residing in
intestinal track. Normally this tapeworm is a parasite of sea animals such as
whales, but reported from more than 200 Japanese patients in Japan,
no patient is reported from the outside of Japan.
A
55-year-old man was admitted to the Nara Medical University Hospital in Japan,
with the complaints of abdominal distension, tenesmus and discharging a cestode
strobila. On his stool examination, eggs in oval-shape with 56.3-65x40-45mm were
found. Under the diagnosis of cestode infection,
anthelmintic treatment with Gastrografin was performed. When 400 ml of
Gastrografin was introduced into duodenal lumen through a tube, roentgenography
revealed that a tape-like worm moved rapidly downwards toward descending colon.
In adult, Scolex absent. The width 7-14 mm, the thickness 1.5- 2 mm.
The length of one segment 0.25-0.8 mm. Each segment always possesed two pairs
of genital organs. Sometimes, a third pair was observed. The uteri had nearly
attained full growth, so the eggs were observed. However, sometimes an immature
uterus was recognized in those segments having
Diarrhoea,
abdominal distension, loss of weight and
fatigue are the common symptoms.Under the diagnosis of cestode infection,
anthelmintic treatment with Gastrografin was performed. When 400 ml of
Gastrografin is introduced into duodenal lumen through a tube, roentgenography
revealed that a tape-like worm can be moved
rapidly downwards toward descending colon. To prevent Diplogonoporus grandis infection, the
marine fishes particularly fish raw like butter fish and sunfish should be
avoided.
Hymenolepis
microstoma
Hymenolepis microstoma is an obligate
parasite. It belongs
to the genus Hymenolepis; tapeworms that cause hymenolepiasis. Hymenolepis microstoma, also known as the rodent tapeworm, is an intestinal
dwelling parasite. H. microstoma is prevalent in
rodents worldwide, but rarely infects humans.
Adult worms live in the bile duct and small intestines of mice and rats, and larvae
metamorphose in the haemocoel of beetles. Worms vary from 4 to
30 cm in length, depending on the age and number of worms within the host.
Adults have completely lost their mouth and intestine. Instead they use their
skin (tegument) to absorb nutrients directly from
the host gut. Worms reproduce sexually via the cross fertilization of segments,
each of which contains a complete complement of male and female reproductive
organs (hermaphroditic). Shelled embryos develop in the
ovaries through spiral
cleavage, to become
infective larvae with 3 pairs of hooks. When ingested by beetles, these larvae
use their hooks and secretory glands to penetrate the gut of the beetle and
enter the haemocoel where they undergo complete metamorphosis into cysticercoid
larvae, replete with an adult scolex, ready for establishment in the final
host.
Life
cycle
Rodents, especially rats, are
definitive hosts and natural reservoirs of H. microstoma. As the
definitive host (rats) eats an infected arthropod, cysticercoids present in the
body cavity transform into the adult worm. Juvenile worms establish in the bile
duct of mice after approximately 3 days movement within the upper gastrointestinal
tract. Once
established in the bile duct, the worms then mature sexually and begin
producing eggs within approximately 1 week. Eggs are released with mouse faeces
and thus dispersal is passive - through the movement and defecation of mice. The
cycle continue as arthropods become intermediate hosts by
ingesting the parasite eggs. When ingested, the eggs develop into
cysticercoids. Humans, especially children, can ingest the arthropods as well
and therefore become infected via the same mechanism.
Pathogenesis
Hymenolepis species and other
tapeworms often exhibit a 'crowding effect' in which the total biomass of the
worms stays more or less constant, regardless of the intensity of infection.
Thus low intensity infections result in larger worms and high intensity
infections produce smaller worms.
Laboratory diagnosis
Under laboratory conditions, H.
microstoma adult infections in mice are typically limited to approximately
12 worms. Adult worm infections in mice held under laboratory conditions may persist
for 6–12 months.
Clinical manifestation
H. microstoma primarily infects rodents, and is only very
rarely found in humans. Human H. microstoma infection is often
asymptomatic, but abdominal pain, irritability, itching, and eosinophilia are among the existing symptoms in a few of
the reported cases.
Treatment and Prevention
Since data regarding praziquantel treatment of H. microstoma is sparse,
scientists have recommended that every case and treatment of H. microstoma
be reported for development of protocols and parasitological purposes.
Mathevotaenia species
The genus Mathevotaenia includes species that
have been found parasitizing mainly mammals throughout the world (rodents,
insectivores, edentates, carnivores, marsupials, bats, and primates), with
isolated reports in reptiles and birds. The life cycles of the species of
Mathevotaenia involve insects, such as cockroaches and butterflies, as
intermediate hosts in which amphicyst develop to larval cestodes or
metacestodes and considered that larvacyst of amphicyst type is a synonymous of
precysticercus.
Mathevotaenia chaquensisn. sp.
(Cestoda, Anoplocephalidae, Linstowiinae) from a Spiny Lava Lizard, Tropidurus
spinulosus, collected in Chaco Province, Argentina, is described. Among the
South American species of Mathevotaenia,
M. argentinensis is most similar to the new species by having similar body
length and number of testes, but the major differences between both species
include the size of suckers, neck, proglottids, testes and egg capsules, and
the shape of the genital atrium and ovary.
Bettle is used in Thailand
and Malaysia for medicinal purposes through which the Mathevotaenia species is acquired. So,
humen is the only accidental host.The laboratory diagnosis can be done by identification
of adult, proglottids and egg (microscopic
identification of eggs in the stool). The disease can be treated with praziquantel and new case should be
reported to the parasitology laboratory. Awareness to the zoonosis parasitic
disease is important step to control the infection like Mathevotaenia species infection in the world.
Mesocestoides spp
Mesocestoides is a parasitic tapeworm which occasionally infects dogs and cats worldwide. So, it is a genus of parasitic
flatworms that has dogs, cats and some wild canids (e.g. foxes,
coyotes, wolves, etc.) as final hosts.
Some species affect also birds, and very seldom humans.
Species which are known to infect dogs
and cats include:
- Mesocestoides
lineatus
and Mesocestoides litteratus,
found in Europe, Africa and Asia.
- Mesocestoides
vogae (= Mesocestoides corti) and Mesocestoides variabilis, found in America.
Incidence depends on the species and the
region. In some European countries more than 70% of the fox population can be
infected. As a general rule it is not very frequent in dogs and cats.
Life
cycle
Mesocestoides
tapeworm have an unusal three-host, first intermediate hosts are arthopods,
second intermediate hosts are small vertebrates and final definative hosts are
cat and dog. Dogs are usually infected with the tetrathyridium larval stages
acquire from ingestion of birds and other small mammals. Adults Mesocestoides
develop from the tetrathyridiums within the dog's intestine and have four
suckers but no hooks. The eggs accumulate within special, thick-walled
parauterine organs which eventually detach from the strobila and are shed into
the dog's feces. Once outside the gravid segments release the proglottids or
oncospheres , which are supposed to be ingested by arthropods. In the intestine
of these intermediate hosts and the young larvae penetrate into their cavity
(hemocoel), where they develop to cysticercoides. The small vertebrates
(snakes, lizards, frogs, birds, rats, mice etc) ingest the infected arthropods
and the cysticercoides are released in their gut. They migrate through the
gut's wall and into various organs (mainly the lungs and the liver) and develop
further to an infective larvae can reproduce asexually. The definitive host
ultimately becomes infected after eating meat contaminated with tetrathyridia.
Humans are not usual definitive hosts, but can serve as such after eating
undercooked meat containing tetrathyridia.
Pathogenesis
Most dogs infected with Mesocestoides
are asymptomatic, although heavy burdens and co-infections may cause ill thriftiness.
However, peritoneal migration by larval tetrathyridium can cause a serious
complication of cystic tetrathyridiosis, with a significantly higher mortality
rate in dogs. Larval tetrathyridia migrated from the gut and proliferate within
the peritoneal cavity, parasitizing abdominal organs and migrating as far as
the inguinal canal, vaginal tunic and testis in some dogs.
Clinical manifestation
The disease caused by Mesocestoides
tapeworms is called mesocestoidosis
or mesocestoidiasis. Mesocestoides does not affect cattle, sheep, goats, swine or horses. Clinical
signs of tetrathyridiosis in dogs include peritonitis (due to intestinal
perforation), ascites, anorexia, vomiting, diarrhea and tachypnea. Some dogs
are subclinically infected and only accidentally diagnosed during routine
ovariohysterectomy or neuter. Mesocestoides species usually parasitize humans in low numbers, causing mild
gastrointestinal symptoms: nausea, diarrhea, abdominal discomfort, vomiting.
Laboratory diagnosis
Diagnosis is based on coprological
identification of Mesocestoides eggs. Co-infections with other
intestinal parasites is extremely common. In peritoneal tetrathyridiosis,
paracentesis and ultrasonography help identify the small white cyst-like larval
stages as well as the occasional intact acephalic pre-adults. PCR assays are
also available to assist speciation of the parasite.
Treatment and
prevention
Praziquantel, emodepside and fenbendazole may be used effectively for
intestinal infections. For peritoneal tetrathyridiosis, subcutaneous
administration of injectable praziquantel at 5 mg/kg is recommended. Dose is
repeated every 2 weeks until paracentesis samples are clear of larval stages.
There are so for no vaccines against mesocestoides tapeworm.
Raillietina celebensis
Raillietina
is a genus
of tapeworms
that includes helminth
parasites
of vertebrates,
mostly of birds.
The genus was named in 1920 in honour of a French
veterinarian
and helminthologist,
Louis-Joseph Alcide Railliet.
Of the 37 species
recorded under the genus, Raillietina celebensis is the most important species in terms of prevalence
and pathogenicity
among wild and domestic birds.
The body of an adult Raillietina
is a typical tapeworm structure, composed of a series of
ribbon-like body segments, gradually enlarging from the anterior end towards
the posterior. It is whitish in colour, highly elongated, dorso-ventrally flat, and entirely covered with a tegument. The entire body is divisible into 3
parts, namely the head region called scolex, followed by an unsegmented neck or
growth region, and then by highly segmented body proper called strobila. As all other cestodes, they are hermaphrodite.
Life cycle
Raillietina require two different hosts for a complete life
cycle. The definitive hosts are mostly wild and domestic birds,
and sometimes humans. The intermediate hosts are insects, such as ants and beetles. Mature eggs are released from the avian host through feaces by detaching the last gravid proglottid. The number of egg cell in each egg
capsule is an identifying feature of each species. Eggs develop into larval forms called oncospheres, which are ingested by ants, and enters the alimentary canal, from where they migrates into the
abdominal cavity of the insect and develops into mature cysticercoids. Development of the juvenile stage in the intermediate host
comprises 5 stages, namely (1) oncosphere stage, (2) lacuna stage, (3) cystic
cavity stage, (4) scolex formation stage and (5) cysticercoid stage, which is
the ultimate infective form. When the insect with infective larvae is ingested
by birds, the cysticercoid is released in host by the action of digestive juices. The rostellar hooks then become
attached to the intestinal wall. New segments begin to form and within 3 weeks
of ingestion of the host, a mature tapeworm develops. Therefore, the entire
life-cycle can take 6 weeks for completion.
Life
cycle
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