2. Case Study
• A 3-year-old male child (body weight 12 kg) presented with periodic
episodes of epigastric pain that increased with food intake and intermit-
tent diarrhoea with vomiting for the last 15 days. On examination his
vitals and routine investigations were within normal limits. The parents
gave the history of expulsion of white and flat segments in a chain,
which were motile.
3. • The child used to play on the ground and also had a habit of putting soil
contaminated fingers into the mouth. Moreover, the movement of
monkeys in the area in search of food was a common phenomenon.
• Stool examination of the child showed the presence of ovoid eggs (size 36–
42 μm) with hexacanth embryo in pyriform sacs. Stool sample submitted
for microscopy did not show any segments (proglottids).
4. Introduction
• Bertiellosis is a zoonotic helminthic parasitic dis- ease caused by the
members of the genus Bertiella.
• Bertiella species are non-taeniid and non-hymenolepid cestodes
(tapeworms) that cause intestinal infections in non-human primates
(definitive hosts).
5. Introduction
• In general, identification of cestodes even at the genus level is not
routinely performed in most of the clinical settings; there- fore, the
majority of them are arbitrarily and falsely assigned to well-known
Taenia spp.
6. History
• Blanchard first described the infection in great apes and named it as genus
‘Bertia’.
• Ancey (1888) described Bertia cambojiensis as type strain. Subsequently, Stiles
and Hassall (1992) revised the genus name to Bertiella .
• The first case of human infection was reported by Blanchard (1913). He
described the infection in an 8-year-old girl from Mauritius and named it as
Bartiella satyri, which was subse- quently renamed Bertiella studeri (now an
Old World species).
7. History
• Meyner (1895) identified tape- worm from two black howler monkeys
(Alouatta caraya) in Paraguay; now they are named as Bertiella mucronata
(a New World species).
• A total of 95 cases (83 and 12 cases by B. studeri and B. mucronata,
respectively) of human bertiellosis have been reported in the literature till
date.
8. Taxonomy
• Genus Bertiella belongs to the Family, Anoploce- phalidae; Order,
Cyclophyllidea; Class, Cestoda; and Phylum, Platyhelminthes in the Kingdom
Animalia.
• Bertiella is the only genus in the family Anoplocephalidae known to cause
infection in humans. So far, 29 species of Bertiella have been described; only
2 of them, B. studeri (Old World species) and B. mucronata (New World
species) are identified to cause human infections.
9. Genomics and proteomics
• Genome analysis in Bertiella species is still prim- itive and proteomics
analysis is lacking.
• Phylogenetic analysis based on NAD1 (nicotinamide adenine dinucleotide
hydrogenase subunit 1), COX1 (cytochrome c oxidase subunit 1), 28SrRNA
and ITS2 (internal transcribed spacer region-2) revealed a monophy- letic
group of Bertiella species within the family Anoplocephalidae.
10. Morphology
Adult
• Adult worms possess head or scolex, neck and segments (proglottids)
like other cestodes.
• Adult worms of B. studeri are usually 10–30 cm long, 1.0–1.5 cm wide
and 2.5 mm thick. B. mucronata are usually longer than B. studeri and
can mea- sure up to 40 cm.
• Scolex of Bertiella is sub-globose with a rudimentary, unarmed rostel-
lum. The base of the scolex is well differentiated from the neck.
• Scolex measures 475 and 800 μm in diameter and has four oval suckers,
two each on the ventral and dorsal sides.
11. Morphology
• Usually, the numbers of proglottids are up to 600 in
B. studeri and 700 in B. mucronata. The proglottids
are usually much wider than the length. Proglottids
contain both male and female reproductive organs.
• They are craspedote, which mean they extend
transversely; they are much wider than their length.
The width and length of gravid proglottids vary (7.8–
11.3 mm wide [mean9.52 mm] and 1.43–2.55 mm
long).
12. Morphology
• Mature proglottids lie at terminal end of the body. They have a single genital pore
that opens irregularly and alternate left to right across the length.
• Ovary and single wide transverse uterus are centrally placed; ovary is fan-shaped
and is on the poral side of the midline. Testes form a transverse band on the
antero-dorsal side of the proglottid. The gravid (mature) uterus is full of eggs.
• Adult worms are usually differentiated into species based on length and width of
gravid segments, size and number of testes, size of vagina and the opening of
genital pore.
13. Morphology
• The eggs of Bertiella spp. have six hooked
(hexacanth) embryo that are typical of
cestode worms. They are ovoid and measure
33–46 μm in width by 36–65 μm in length.
• They have an outer eggshell and inner
chitinous membrane (inner envelope) with
an albuminous layer in between. The inner
envelope contains a distinct pyriform
apparatus; the hexacanth embryo is located
within the pyriform apparatus.
• The envelope extends filamentous
projections - around the embryo.
14. Larva
• The larvae of Bertiella spp. are called cysticercoids.
• They are found in the body of the arthropod intermediate hosts (oribatid mites).
• After ingestion of eggs by oribatid mites, the oncospheres (hexacanth embryos)
are released and develop into cysticercoids inside the body of mites within 9 days
of ingestion. Cysticercoids are pyriform in shape with everted unarmed sco- lex
by which they attach to the intestinal wall of the definitive host and develop into
adults.
15. Laboratory Animals
• Non-human primates are the natural definitive host of Bertiella spp.
• B. studeri usually infects monkeys of the genera Anthropopithecus, Cercopithecus,
Cynomologus, Macaca and vari- ous other species, occasionally chimpanzees (Pan
troglodytes) and gibbons (Hyalobates hoolock).
• B. mucronata can infect the monkeys belonging to the genera Callicebus and
Alouatta.
• Chimpanzees in zoo or kept in animal house can also be infected.
• Other animals like rodents, dermopterans and Australian marsupials can also be
infected by Bertiella spp.
17. Definitive Hosts
• Monkeys of the genera Anthropopithecus, Cercopithecus,
Cynomologus and Macaca and grey langur (Presbytis entellus)
are the definitive hosts of B. Studeri.
• Monkeys belonging to the genera Callicebus and Alouatta are
the definitive hosts of B. mucronata. Chimpanzees (Pan spp.)
are known to be the definitive hosts for both species.
• Other animals like rodents, dermopterans and Australian
marsupials are also reported as definitive hosts for other
Bertiella spp.
18. Intermediate Host
• Several species of oribatid mites
(arthropods) are the intermediate
hosts for Bertiella spp.
• Infective stage: Cysticercoid, the
larval stage of the parasite, is the
infective stage.
19. Transmission of Infection
• The infection is transmitted by the following ways:
(a) ingestion of mites by the natural non-human primates and accidental
inges- tion of mites by humans,
(b) consumption of mite contaminated fruits and vegetations, and
(c) ingestion of mite contaminated soil, especially by children.
20. Human infection
• Humans get infection accidentally by ingesting the mites and intaking contaminated fruits and
vegetations.
• Children acquire infection by ingestion of contaminated soil. The cysticercoids released from
mites attach to the small intestine with the help of unarmed scolices and subsequently develop
into mature adults.
• The adult parasites are usually found in the lower two- thirds of the small gut.
• They lay eggs in the intestine, which are passed in the faeces. Around two dozen eggs are passed
at a time. White, flat and actively motile segments/proglottids can also be expelled either singly
or in a chain of 8–16 in stools. Characteristic proglottids in stool can be seen with naked eyes.
21. Pathogenesis
• Pathogenesis and pathology of Bertiella infections are not well described but
presumed to be similar to other intestinal cestodes.
• The adult parasite attaches with its suckers to the lower part of the small
intestine and then extends its rostellum into the intestinal mucosa, thereby
causing damage to the epithelium.
•
22. Pathogenesis
• This initiates an inflammatory
response involving mast and goblet
cells at the initial stage followed by
infil- tration of neutrophils,
eosinophils and lymphocytes.
• In young children, excessive worm
burden can lead to small intestine
obstruction.
23. Infection in Humans
• The clinical spectra of bertiellosis are not well- defined because of the limited number of clinical
cases.
• Most cases are asymptomatic in adults. Symp- tomatic cases are more common in children.
• The major symptoms are epigastric pain usually fol- lowing meal, nausea, anorexia, diarrhoea and
abdominal distension. Perianal itching in some cases had also been reported.
• Expulsion of segments/proglottids in stool may sometimes lead to stress and psychological
problems.
• Heavy parasite burden in young children can cause physical obstruction of the small intestine.
29. Treatment
• Early diagnosis and treatment can prevent disease chronicity and progression to severe infections,
especially in children.
• Single dose praziquantel 40 mg/kg body weight followed by second dose after 3 weeks is the treatment
of choice.
• Some cases were successfully treated by single dose niclosamide (500 mg–2 g).
• However, treatment failure can occur with niclosamide.
• The most commonly used anthelminthic such as albendazole is not effective in clinical and
microbiological cure.
• Mild purgatives are also given following anthelminthic therapy to expel the worm
30. Prevention and Control
• Public awareness and knowledge about the para- site among the health care
personnel can help in prevention of Bertiella infections.
• Zookeepers and laboratory personnel handling non-human primates need to
be educated about these infections.
• They should maintain strict personal hygiene.
• Proper hand hygiene and cleanliness are important especially in small children
to prevent ingestion of soil. Proper cleaning and washing of fruits before
consumption should be routinely practised.
31. Case study
• Based on the morphology of the eggs, the diagnosis of bertiellosis was made;
species identification was not possible in the absence of proglottids.
• How- ever, as per epidemiological evidences, it was likely Bertiella studeri since
from Asia till date only Bertiella studeri had been reported. The child was treated
with 40 mg/kg single dose praziqunatel and the treatment was repeated after
3 weeks.
• On follow up at 6 weeks after completion of treatment, the child was asymp-
tomatic and stool examination did not reveal any egg or proglottid of Bertiella or
any other parasite.
32. MD questions
• Name the parasites which may be transmitted to humans by ingestion
of infected mites, beetles and ants.
• How can you differentiate between Bertiella studeri and
Bertiella mucronata?
• Mention the importance of monkeys in zoo- notic parasitic infections.
