ORIGINAL ARTICLE /ARTÍCULO ORIGINAL
FASCIOLOSIS: AN EMERGING ZOONOTIC TREMATODE INFECTION AFFECTING
THE LIVER- A REVIEW
FASCIOLOSIS: UNA INFECCIÓN EMERGENTE ZOONÓTICA POR TREMATODOS
QUE AFECTAN AL HÍGADO- UNA REVISIÓN
1 1 2 1
Nazima Gul *,Hidayatullah Tak , Khalid M. Fazili and Tanveer A. Sofi
1 2
Department of Zoology, University of Kashmir, Srinagar- 190006, Kashmir, Department of Biotechnology, University of
Kashmir, Srinagar- 190006, Kashmir, India.
*nazimagul1@gmail.com
Neotropical Helminthology, 2016, 10(1), ene-jun: 127-133.
ABSTRACT
Keywords: Aetiological agent - Fasciolosis - Parasitoproteomic - Re-emerging - Zoonosis
Zoonotic trematodiasis has emerged at a rapid pace and frequently with significant human and
financial costs. The most important and well-known human zoonoses caused by trematodes
affecting liver is Fasciolosis. The present work has been carried out to review on the extensive
literature on Fasciolosis in detail that is increasing rapidly in incidence and geographic range.
Reasons for the increase in the infection caused by Fasciola spp. are likely to be multifactorial.
The use of parasitoproteomics as a powerful experimental approach, and its potential benefits to
trematode biology are also discussed in relation to the future control of trematode infections of
animals and humans. The aim is to make more young researchers vigilant about the importance of
this critical issue. Global efforts to expand joint planning, information sharing, and financial
support of a range of global efforts aimed at detection, verification, and response are increasingly
important. Failure to jointly pursue these goals in a balanced approach has already contributed to
new, re-emerging, and drug resistant etiological agent causing fasciolosis. The current review
highlights the need for basic laboratory research to update the knowledge on zoonotic fasciolosis.
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ISSN Versión impresa 2218-6425 ISSN Versión Electrónica 1995-1043
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RESUMEN
Palabras clave: agente etiológico - fasciolosis - Parasitoproteomic - re-emergentes - Zoonosis
Las trematodiasis zoonóticas han surgido a un ritmo rápido y frecuente con un importante costo
humano y financiero. La más importante y conocida zoonosis humana causada por trematodos,
que afectan al hígado es la fasciolosis. El presente trabajo ha sido realizado para tener una
revisión exhaustiva de la extensa bibliografía sobre la fasciolosis en detalle que está aumentando
rápidamente en incidencia y alcance geográfico. Las razones para el aumento de la infección por
Fasciola spp son probablemente multifactoriales. El uso de la parasitoproteómica como un
poderoso enfoque experimental, y sus potenciales beneficios para la biología de trematodos
también se examinan en relación con el control futuro de las infecciones por trematodos en
animales y en seres humanos. El objetivo es hacer a los jóvenes investigadores más vigilantes
sobre la importancia de esta temática crítica. Los esfuerzos mundiales para ampliar la
planificación conjunta, el intercambio de información, y el apoyo financiero a una serie de
esfuerzos mundiales encaminados a la detección, verificación y respuesta son cada vez más
importantes. El fracaso por perseguir estos objetivos conjuntamente con un enfoque equilibrado,
ya han contribuido a nuevas, a re-emergentes, y a agentes etiológicos resistentes
terapéuticamente causantes de fasciolosis. La actual revisión resalta la necesidad de
investigación básica de laboratorio para actualizar los conocimientos sobre la fasciolosis
zoonótica.
Neotropical Helminthology. Vol. 10, Nº1, ene-jun 2016
INTRODUCTION
Zoonoses are infections and diseases that are
transmissible between animals and humans.
The severity of these diseases in humans can
vary from mild symptoms to life-threatening
conditions. Zoonotic infectious agents are
among the most prevalent on earth and are
thought to be responsible for >60 per cent of all
human infections and 75 per cent of emerging
human infectious diseases (Cunningham,
2005). With the inherent complexity of the
biological and social systems involved in
disease emergence, it is not possible to
accurately predict the infectious agents
destined to emerge. Yet, the probable reasons
for the emergence of new zoonotic diseases are
many and include, changes in social, dietary or
cultural mores, environmental changes, and
the improved recognition of heretofore
neglected infections often coupled with an
improved ability to diagnose infection
(McCarthy & Moore, 2000). Increased
demand for livestock products in many
developing countries is viewed as a market,
which can potentially be exploited by poor
livestock keepers and offer a pathway out of
poverty for some (Delgado et al., 1999).
However, the zoonotic diseases may lead to
restrictions on the sale of livestock products
and therefore limit the access of the poor to
these new markets An emerging zoonosis is
defined as 'a zoonosis that is newly recognized
or newly evolved, or has occurred previously,
but shows increases in incidence or expansion
in a geographic, host or vector range
(Slingenbergh, 2004). Fascioliasis is among
one such emerging zoonotic diseases.
Fasciolosis
Fasciolosis, a major veterinary problem
worldwide due to the economic losses it causes
in animal husbandry, has recently become
Gul et al.
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(2008) indicated that Radix auricularia (Held,
1836) also acts as intermediate host for F.
hepatica in Oman.
Life cycle of Fasciola spp.
The life cycle of Fasciola spp is complex and
includes a snail and a mammal as intermediate
and definitive hosts respectively. Mammals
(human, cow, sheep, rabbit, etc.) get infected
by ingestion of the quiescent larvae
(metacercariae) encysted in the vegetation.
Infection has also been reported in birds
(Despommier, 1987). An interplay of extrinsic
signals from the host (digestive enzymes, bile
salts, redox potential, pH, and temperature
among others) and intrinsic factors from the
parasite (enzymes and secretions) determine
the emergence of motile larvae (Fried, 1994).
The newly excysted juveniles (NEJ) actively
penetrate and transverse the gut wall into the
peritoneal cavity within two or three hours. By
four or five days post-infection the parasites
reach and penetrate the liver, and continue
burrowing through the parenchyma for several
weeks. Within the major bile ducts the
parasites mature and start to release eggs, that
can be found in the bile and feces from 8 weeks
post-infection (Andrew, 1999).
Factors affecting the emergence of zoonotic
diseases
Factors associated with the emergence of
Fascioliasis in human, wildlife and domestic
animals have been explored by various
researchers. According to one perspective,
disease emergence is the result of two
sequential processes:
a) Adaptation of a pathogen (Fasciola) to a
new host: As elegantly demonstrated by,
pathogen strains entering a new host
population may initially have an overall
reproductive number of less than one (R0 < 1)
that leads to the extinction of the pathogens,
but prior to extinction, some may evolve and
increase their virulence to give R0 > 1,
allowing them to persist and spread into a new
increasingly important in public health, with
human reports increasing in number and the
description of human endemic areas (Mas
Coma et al., 2009). The epidemiological
picture of human Fasciolosis has changed in
recent years. The number of reports of humans
infected with Fasciola hepatica (Linnaeus,
1758) has increased significantly since 1980
and several geographical areas have been
described as endemic for the disease in
humans, with prevalence and intensity ranging
from low to very high (Mas Coma et al., 1999).
In the past, Fasciolosis was limited to
populations within well-defined watershed
boundaries; however, recent environmental
changes and modifications in human
behaviour are defining new geographical
limits and increasing the populations at risk
(Soliman, 2008). In recent times, human
Fasciolosis has apparently emerged or re-
emerged as well recognized neglected
zoonotic infection because of improved
diagnosis. Thus, human Fasciolosis can no
longer be considered merely as a secondary
zoonotic disease but must be considered to be
an important human parasitic disease.
Etiology
Fasciola hepatica and Fasciola gigantica
(Cobbold, 1855) are the two trematodes which
cause human and animal Fasciolosis. These
hepatic helminth parasites are present around
the world infecting a great variety of mammals
as definitive hosts, but using only some species
of snails which act as their sole intermediate
host. F. hepatica is found in the five continents;
however, F. gigantica is primarily distributed
in tropical regions excluding America
(Fuentes, 2006). Throughout the greater parts
of world, F. hepatica is mainly transmitted by
Galba truncatula (Müller, 1774) or by snails
not readily distinguishable from it on grounds
o f m o r p h o l o g y o r e c o l o g i c a l
requirements,whereas, F. gigantica is
transmitted by varieties of the super species
Lymnaea auricularia (Linnaeus, 1758) as
reported by Kendall, 1954. However, Soliman
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Neotropical Helminthology. Vol. 10, Nº1, ene-jun 2016 Gul et al.
Early detection and rapid responses
and
Control via the food chain, consumer
empowerment and certification.
Fasciolosis can be controlled by adopting the
following parameters:
Use of Molluscicide
Application of molluscicides in bait form is a
new approach and technique for the control of
fascioliasis for controling of harmful snails.
Active components ferulic acid, umbelliferone
(Ferula asafoetida), eugenol (Syzygium
aromaticum) and limonene (Carum carvi) are
very effective molluscicides when release
directly in aquatic environment (Kumar et al.,
2006)
Phytotherapy of Vector Snail to Kill
Fasciola Larva
Phytotherapy of infected snails by the active
components is one of the new method to
control the fascioliasis without killing the
vector snail, an important components of the
aquatic ecosystem. Sunita & Singh (2011)
during their study clearly indicated that the
Zingiber officinale (citral), Ferula asafoetida
(ferulic acid, umbelliferone), Azadirachta
indica oil (azadirachtin), and Allium sativum
(allicin) have sufficient larvicidal activity
against different larva of F. gigantica in in vivo
and in vitro treatments.
Myrrh (Mirazid) which is an oleo-gum resin
from the stem of Commiphora molmol tree
(Family Burseraceae) has been used in folk
medicine since ancient Egyptians (Myrrh) and
registered in Egypt for the treatment of
schistosomiasis and fascioliasis. (Yakoot,
2010). The majority of these studies reported
that Mirazid® has higher than 90% cure rates,
that even higher in mixed than single
trematodal infections in humans and in farm
animals.
Chemotherapy
A series of chemotherapeutic agents are
host population (Antia et al., 2003).
b) Spread of the Fasciola into the new
population
Diagnosis of Fascioliasis
The traditional way for diagnosis of
Fascioliasis is coprological examination. But
during the acute phase, no eggs can be seen
because the parasites have not yet matured, and
thus positive reactions may not appear at such
an early stage. Moreover, consumption of beef
or lamb's liver may cause trematode eggs to
appear in feces and consequently give a false
positive result in the coprological
examination. A number of immunobiological
tests have been used in an effort to diagnose the
infection during the prepatent period,
including a skin test, complement fixation,
i m m u n o f l u o r e s c e n c e ,
i m m u n o e l e c t r o p h o r e s i s ,
counterimmunoelectrophoresis, enzyme-
linked immunosorbent assay (ELISA), and
immunoelectrotransfer. The search for
appropriate antigens has improved the
specificity and sensitivity of these tests, but
there are still cross-reactions, especially with
schistosomiasis (WHO, 2003). PCR
techniques are also used for identification of F.
hepatica and F. gigantica infections (McGarry
et al., 2007). Several ELISAs for Fasciola
have been developed and most rely on the
detection of antibodies against fluke-secretory
proteins (Espinoza et al., 2007). An accurate
serological test using recombinant cathepsin L
protease produced in yeast has been developed
by Dalton and colleagues (O'Neill et al., 1999).
Control of Fascioliasis
As Fascioliasis falls under three typological
diseases, i.e., neglected zoonoses, emerging
zoonoses and foodborne diseases (WHO
2003), so it requires diversified approaches to
combat it which include:
Better health systems,
Development and poverty alleviation
measures, Public awareness,
Emergency preparedness,
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Neotropical Helminthology. Vol. 10, Nº1, ene-jun 2016 Fasciolosis: an emerging zoonotic trematode infection
mg/kg is the drug of choice in human
fasciolosis (Savioli et al., 1999).
Anti Fasciola vaccines: An additional
advance in the control of animal fasciolosis
will be provided by the development of anti-
Fasciola vaccines against species specific
antigens. Although a range of vaccines against
F. hepatica infections have been developed by
several laboratories (McManus & Dalton,
2006) but none are commercially available at
present. Fatty acid binding protein (FABP) is
an attractive vaccine candidate and a drug
target for controlling Fasciolosis caused by F.
gigantica in ruminants (Sriveny et al., 2003).
available for the treatment of animal
Fasciolosis, including closantal, clorsulan,
rafoxanide, nitroxynil and triclabendazole
(Boray, 1999). However, triclabendazole
resistant parasites have been reported in
Europe and Australia. The experimental
fasciolicides such as artemether and OZ78
have activity against TCBZ-resistant flukes
(Keiser et al., 2007).But, chemicals runoff into
water supplies will make the chemical control
of fasciolosis more difficult in the future
(Dalton et al., 2003b). Most importantly,
government and consumer concern about
chemical and antibiotic residues in animal
foods (milk and meat). For high efficacy and
safety, triclabendazole (Egaten) in dose 10–12
•drug treatment in
host
•use of vaccine
candidates
(antigenic
components) for
control
•to Kill Fasciola
by usage of active
components in
plants
•in bait form
Molluscicide Phytotherapy
of snails
Chemotherapy
(Anti
Fasciolids)
Anti Fasciola
vaccine
Figure 1. Parameters for control of fascioliasis.
than ever. Experimental approaches should be
armed with recent advanced technologies like
post genomics and proteomic analysis to
combat such global issue in the future.
Though there is advance in our understanding
of biology of helminth parasites, Zoonotic
Fasciolosis remain endemic in many parts of
world. Thus the need for basic laboratory
research on zoonotic Fasciolosis is stronger
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