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Bertiella
Erin DeLaney - 2/26/2010
Introduction
Bertiella is a cestode tapeworm parasite that primarily infects nonhuman primates, rodents
and Australian marsupials. Occasionally, human infections have been documented by one of
two species: Bertiella studeri, or Bertiella mucronata. These infections present with symptoms
similar to most tapeworm cases, and are frequently misdiagnosed. Bertiella transmission is
through oribatid mites that are present in the soil of problem areas, and can be easily
prevented by avoiding contact with nonhuman primates, rodents and soil in problem areas.
Agent (classification and taxonomy)
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Anoplocephalidae
Species: Of 29 different Bertiella species, only two can infect humans: Bertiella studeri
(majority of human cases), and Bertiella mucronata
Synonyms
Bertiella
Bertiella
Bertiella mucronata
Bertiella studeri
Bertielliasis
Inermicapsifer
History of Discovery
The suborder of Anplocephala was named in 1891 by Blanchard, and the family
Anoplocephalidae created in 1928 by Mola. Bertia, already named by Blanchard in 1891, was
placed in this group. With some shuffling throughout the years, this family remained mostly
the same, categorized by its similar transmission by orbatid mites. As of 1994, within the
Cyclophyllidea order, Anoplocephalidae is considered one of the four subfamilies established
by classifying uterine development, the others being Linstowiinae, Inermicapsiferinae and
Thysanosomatinae.
Bertia was first described in a chimpanzee as Bertia satyri, and in an orangutan as B. studeri
by Blanchard (1891). The genus Berti was later changed to Bertiella on the proposal from
Stiles and Hassall (1902), and the human forms were identified as Bertiella studeri and
Bertiella mucronata. The first case of human bertielliasis was reported by Blanchard in 1913
from a child in Mauritius.
Clinical Presentation in Humans
Bertielliasis can be asymptomatic, or present with symptoms similar to many other
tapeworms. These can include:
Intermittent epigastric pain after meals accompanied by nausea,
diarrhea,
anorexia,
no fever and loss of weight,
generally, a tender abdomen.
Transmission
While it is a parasite infecting mostly primates, rodents and other mammals, Bertiella is
transmitted to humans by the accidental consumption of oribatid mites, which are the
intermediate hosts. These mites are important components of soil fauna, and are widely
distributed. In the rare cases that dogs and humans have contracted an infection, it is
attributed to proximity and frequency of soil contact in certain regions. More than 50 cases of
Bertiella have been cited, with a high frequency of those being children. In cases in Mauritius,
the infection was traced back to the consumption of guavas which had been picked up from
the ground.
Reservoir
Non-human primates, rodents, Australian marsupials.
Vector
None.
Incubation Period
Unknown.
Morphology
Like all Cyclophyllidea, Bertiella has a scolex, suckers, and many segments called proglottids.
These are released into the body from the adult tapeworm, contain both male and female
anatomical structures, and are in stages of mature, postmature and gravid. In general, human
Bertiella morphology is not well understood due to the rarity of infection, and therefore limited
possibility for study and observation. Particularly lacking are descriptions of adult stages of
the species. Most common are studies of proglottids passed in stool samples of infected
hosts. Studies have shown that specimens collected from humans are essentially
morphologically the same as specimens collected from monkey hosts, except for some
anatomical differences in reproductive organs. However, these discrepancies in morphological
findings have led researchers to postulate that there may be more than two human bertiella
species, as previously believed.
These gravid proglottids in stool are white and can measure around 11mm for maximum
length and 8mm for maximum width. Full tapeworm observations in the past have included a
worm that was 130mm. long, 15mm. in width, and 2.5mm. in thickness. It had a scolex, neck,
and 418 proglottids.
Differences in human species:
B. mucronata has smaller eggs than B. studeri.
There are filaments arising from the pyriform apparatus clearly identifiable on B. studeri but
not B. mucronata.
Life Cycle
There is relatively little known about the life cycle of Bertiella, but inferences and assumptions
can be made about it through observations of specific parts of the worm, and knowledge of
other cases in the same family (Anoplocephalidae).
Anoplocephalids are heteroxenous parasites and require both an intermediate and definitive
host to complete their cycle. For Bertiella, nonhuman primates are generally the definitive
host, and oribatid mites are the intermediate host.
In humans:
Infection occurs when a human inadvertently consumes an oribatid mite infected with Bertiella
larvae. Within the human (the definitive host) the larvae migrate through the GI tract, using
their morphology to stick onto parts of the intestines.
From there, these adult tapeworms can live for years, feeding off the host and
producing/shedding eggs and proglottids.
These eggs and prgoglottids are passed in stool, and the eggs are taken up by oribatid mites
(the intermediate host) in the soil.
In these mites, Bertiella develops into the infective cysticeroid and begin producing larvae.
The mites are then consumed by humans again, or by the nonhuman primate or rodent
reservoir.
Diagnostic Tests
The most common and successful way to identify Bertiella is by the observation of eggs or
proglottids in stool. They can be white, around 8mm wide and 11mm long, and moving.
It can also be identified by presenting with common signs and symptoms in an area where
disease is present, and there is close contact with soil and/or nonhuman primates. In many of
these areas, other parasitic diseases can be a problem to the population, and finding the
proglottids in stool samples can be the only way to distinguish Bertiella from other parasites.
Management and Therapy
There is not an officially established treatment due to rarity of disease. Most are
misdiagnosed anyway and treated with general medicines against cestodes. One record of
treatment in a Bertiella case in Equatorial Guinea, documented a patient treated with
praziquantel in a 40 mg/kg body weight, in a single dose, followed by a second, similar dose
20 days later. From then, the proglottid excretion and oesophageal pain desisted.
In another instance of B. studeri infection, niclosamide was recommended as an appropriate
anti-helminthic therapy.
Epidemiology
The two forms of human Bertiella are distributed geographically: B. studeri is a parasite of
monkeys in the Old World (Asia and Africa), and B. mucronata is found in the New World
(South America and Cuba).
As of 1997, 45 cases had been reported in the world's literature:
- Of 40 cases ascribed to B. studeri, 4 were reported from Mauritius, 11 in India, 9 in Sumatra
(Indonesia), 2 in Java (Indonesia), 1 each in Borneo (Indonesia), Singapore, St. Kitts,
Philippines, Malaysia, Sri Lanka, Yemen, Equatorial Guinea, Thailand, and Gabon. Additional
case reports were published from Vietnam in 2003 and China in 2006.
- Of 5 cases ascribed to B. mucronata, 2 were reported from Brazil, and 1 each from
Argentina, Cuba and Paraguay. Reports of B. mucronata in monkeys in Peru have also
surfaced.
Public Health and Prevention Strategies/Vaccines
Due to the low occurrence of this infection in humans, and non-lethal symptoms, it is not
considered a public health crisis where large steps have to be taken toward prevention or the
development of a vaccine. The most common way to prevent this infection in humans is to
avoid contact with nonhuman primates and the soil in their proximity. In Mauritius and other
similar regions, children (specifically) and adults are strongly discouraged from eating guavas
that have fallen on the ground.
Useful Web Links
http://parasites.stanford.edu
http://www.dpd.cdc.gov/DPDX/Default.htm
References
Galán-Puchades et al. “Morphology of Bertiella studeri (Blanchard, 1891) sensu Stunkard
(1940) (Cestoda: Anoplocephalidae) of human origin and a proposal of criteria for the
specific diagnosis of bertiellosis.” Folia Parasitol. vol 47(1), pgs 23-28, 2000.
Galán-Puchades et al. “Human Bertiella studeri in Equatorial Guinea.” Transactions of the
Royal Society of Tropical Medicine and Hygiene. Vol 91, pg 680, 1997.
Denegri et al. “Anoplocephalid cestodes of veterinary and medical significance: a review.”
Folia Parasitologica. Vol 45(1), pgs 1-8, 1998.
Sun, Xin. “Bertiella studeri Infection, China” CDC Emerging Infectious Diseases. Vol 12, No. 1
Jan 2006
Bhagwant, S. “Human Bertiella studeri (family anoplocephalidae) infection of probably
southeast Asian origin in Mauritian children and an adult. The American Journal of
Tropical Medicine and Hygiene. Vol 70(2), pgs225-228, 2004.
John, David T., and Petri, William A. Jr. Markell and Voge's Medical Parasitology. Saunders
Elsevier, St. Louis, 2006.
Stunkard, Horace W. “The Morphology and life history of the cestode, Bertiella studeri.”
American Journal of Tropical Medicine and Hygiene. Vol 56, 610-612. 1940.
GIDEON – Global Infectious Diseases and Epidemiology Network.
(http://web.gideononline.com)
Images
Source: CDC
Title: Bertiella studeri
Description: Proglottids of Bertiella studeri
Source: CDC
Title: Bertiella studeri ova – patient in China
Description:Ova collected from proglottids of Bertiella studeri.
Source: Galán-Puchades et al
Description: Observational drawings of B. studeri
A) egg and pyriform apparatus; B-D) transversal views; B) cirrus sac and vagina; C) mature
proglottis; D) postmature proglottis. Scale bars: A = 0.01mm; B = 0.1 mm. C, D = 1mm