Chuyên mục: Nghiên cứu khoa học

Tháng Mười 11, 2017

N. Vu Thi a, P. Dorny b, G. La Rosa c, T. To Long a, C. Nguyen Van d, E. Pozio c,*
a Parasitology Section, National Centre for Veterinary Diagnosis, Hanoi, Vietnam
b Department of Animal Health, Institute of Tropical Medicine, Antwerp, Belgium
c Community Reference Laboratory for Parasites, Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanita `, Rome, Italy
d Department of Parasitology, Hanoi Medicine University, Hanoi, Vietnam
Although several outbreaks of Trichinella infection among humans have occurred in
northwestern Vietnam, no information is available on the circulation of Trichinella among
domestic pigs. The objective of the present study was to estimate the seroprevalence of
anti-Trichinella IgG in free-roaming pigs (Sus scrofa) in the Son La province of northwestern
Vietnam, where a human outbreak of trichinellosis occurred in June 2008. Serum samples
were collected from free-roaming pigs of four communes of the Bac Yen district (Son La
province) and tested for Trichinella antibodies with a commercial ELISA kit using
excretory/secretory antigens. Of 1035 pigs from which serum samples were collected, 206
were positive (19.9%). There was a significant difference in the prevalence among
communes (x2 = 22.87, 3 d.f., p < 0.0001). Muscle samples from 76 serologically positive pigs were tested by artificial digestion. Trichinella larvae were detected in 11 (14.5%) of them. The larvae were identified by multiplex PCR as Trichinella spiralis. This study provides the first data on the circulation of T. spiralis in domestic pigs reared in Vietnam, and the results are useful for evaluating the risk of infection for humans. The results indicate that pigs act as a reservoir and play an important role in the maintenance of the domestic cycle of T. spiralis in northwestern Vietnam.  2009 Elsevier B.V. All rights reserved.

Tháng Mười 11, 2017

T. G. T. Nguyen1, T. H. Le2, N. V. De3, T. T. Doan4, T. H. T. Dao1, J. Vercruysse5 and P. Dorny5,6
1 National Institute of Veterinary Research, Hanoi, Vietnam
2 Department of Immunology, Institute of Biotechnology, Hanoi, Vietnam
3 Department of Parasitology, Hanoi Medical University, Vietnam
4 Viet Duc Hospital, Hanoi Medical University, Vietnam
5 Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
6 Institute of Tropical Medicine Antwerp, Belgium
Summary Fasciolosis has emerged as an important zoonotic disease in many parts of the world. In recent years, an
increasing number of human cases were reported in Vietnam. In this study, the 27-kDa component
protein from the excretory ⁄ secretory production of adult Fasciola gigantica, purified by high
performance liquid chromatography, was assessed in an enzyme-linked immunosorbent assay (ELISA) to
detect antibodies against Fasciola spp. for diagnosis of human fasciolosis. The ELISA showed a high
sensitivity (100%) and specificity (97.67%) when tested on patients with fasciolosis, other parasitic
infections, cholangiocarcinoma and on healthy controls. The assay was applied for diagnosis on 143
patients in the Viet Duc-Hanoi hospital who presented with clinical signs of liver disease and lesions in
their livers as shown by imaging techniques. Antibodies were found in 37 (25.9%) of these patients, of
whom only 3 shed Fasciola eggs in their stools (2.1%). The excellent response to triclabendazole
treatment of 37 sero-positive patients confirmed the diagnosis of fasciolosis. This study demonstrated the
diagnostic potential for human fasciolosis of the 27-kDa antigen ELISA. Fasciolosis should be
considered in the differential diagnosis of hepatic disease in Vietnam.
keywords Fasciolosis, diagnosis, Enzyme-linked immunosorbent assay, hepatic disease, Vietnam

Tháng Chín 29, 2017

Thanh Giang Thi Nguyen a, Nguyen Van De b, Jozef Vercruysse c, Pierre Dorny c,d, Thanh Hoa Le e,*
a National Institute of Veterinary Research, Hanoi, Viet Nam
b Department of Parasitology, Hanoi Medical University, Viet Nam
c Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
d Institute of Tropical Medicine, Antwerp, Belgium
e Department of Immunology, Institute of Biotechnology, Hanoi, Viet Nam
Ribosomal RNA sequences (361 or 362 bp) of the second internal transcribed spacer 2 (ITS-2) and a portion of mitochondrial cox1 (423 bp) for Fasciola spp. obtained from specimens collected in indigenous and
hybrid goats and sheep in Vietnam were characterized for genotypic status and hybridization/introgression. Alignment of 48 ITS-2 sequences (also those from goats and sheep in this study) indicates that F.
gigantica and F. hepatica differ typically from each other at seven sites whereas one of these is a distinguishing deletion (T) at the 327th position in F. gigantica relative to F. hepatica. The isolates from the
mountainous goats in the North of Vietnam (Yen Bai province) showed the ITS-2 composition relatively
identical to that of F. hepatica. The ITS-2 sequences from populations of Fasciola isolates in goats had
probably experienced introgression/hybridization as reported previously in other ruminants and
humans. All Vietnamese goat-of-origin specimens had high pairwise percentage of mitochondrial cox1
sequences to F. gigantica (97–100%), and very low identity to F. hepatica (91–93%), suggesting their maternal linkage to be traced to F. gigantica. The presence of hybrid and/or introgressed populations of liver
flukes bearing genetic material from both F. hepatica and F. gigantica in the goats/sheep in Vietnam,
regardless of indigenous or imported hosts, appears to be the first demonstration from a tropical country.
 2009 Elsevier Inc. All rights reserved

Tháng Chín 29, 2017

Abstract
The two species common of liver fluke, Fasciola hepatica and Fasciola gigantica, cause human fascioliasis. Hybrids between these species, and introgressed forms of Fasciola, are known from temperate and subtropical regions of eastern Asia. Here, we report the presence
of hybrid and/or introgressed liver flukes in Vietnam where it has recently been recognised that human fascioliasis is an important zoonotic disease. Specimens examined came from domestic stock (cattle and buffalo) at slaughter and also from human patients. DNA
sequences were obtained from the nuclear ribosomal second internal transcribed spacer (ITS-2) and from portions of two mitochondrial
protein-coding genes. Mitochondrial sequences in every case were similar to those of Fasciola gigantica. Nuclear ITS-2 sequences
belonged to one or other of the Fasciola species, or, sequences from both were found in the same individual worm. This study extends
the known range of hybrids or introgressed forms of Fasciola into tropical regions of Asia.
 2007 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: Fasciola gigantica; Fasciola hepatica; Hybridisation; Internal transcribed spacer region; Introgression; Vietnam

Tháng Chín 22, 2017

Although fishborne zoonotic trematodes that infect the
liver are well documented in Vietnam, intestinal fishborne
zoonotic trematodes are unreported. Recent discoveries of
the metacercarial stage of these flukes in wild and farmed
fish prompted an assessment of their risk to a community
that eats raw fish. A fecal survey of 615 persons showed a
trematode egg prevalence of 64.9%. Infected persons were
treated to expel liver and intestinal parasites for specific
identification. The liver trematode Clonorchis sinensis was
recovered from 51.5%, but >1 of 4 intestinal species of the
family Heterophyidae was recovered from 100%. The most
numerous were Haplorchis spp. (90.4% of all worms recovered). These results demonstrate that fishborne intestinal
parasites are an unrecognized food safety risk in a country
whose people have a strong tradition of eating raw fish.

Tháng Chín 22, 2017

Summary objectives To assess the risk of fishborne zoonotic trematode (FZT) infection in fish reared in
wastewater-fed ponds in peri-urban areas of northern Vietnam.
methods We collected 1 200 fish from aquaculture systems receiving wastewater from the cities of
Hanoi and Nam Dinh in northern Vietnam and examined them for zoonotic metacercariae. Collection
periods were fall (October–November 2005) and spring (April–June 2006). The fish were digested in
pepsin and metacecariae, recovered and identified by light microscopy. Data were expressed as both
prevalence and intensity of infection.
results FZT metacercariae were recovered from fish samples at both sites and during both
sampling periods. The overall prevalence of FZT was 5% (2.0% in fall and 6.5% in spring) in fish
from Hanoi and 4.6% (2.4% in fall and 5.7% in spring) in fish from Nam Dinh. The higher prevalence
in the warmer months was likely due to ecological factors such as temperatures and population
dynamics of the snail vectors. All metacercariae recovered were zoonotic intestinal trematodes of the
family Heterophyidae. The infected fish included tilapia (Oreochromis niloticus) and three species of
carps, including silver carp (Hypophthalmichthys molitrix), which is commonly used for the
preparation of raw fish dishes. Intensities of infection were relatively low.
conclusion Fish raised in peri-urban wastewater-fed aquaculture systems are at risk of infection with
trematode parasites, which can be transmitted to humans through consumption of raw or improperly
prepared fish. However, the prevalence was low as compared to previous findings of FZT in nonwastewater fish elsewhere in Vietnam. Studies are needed to assess the relative importance of different
risk factors for transmission and control of FZT in wastewater-fed aquaculture.
keywords fishborne zoonotic trematodes, wastewater, aquaculture, Haplorchis pumilio, Haplorchis
taichui, Centrocestus formosanus, Vietnam

Tháng Chín 22, 2017

A total of 964 adult fish farmers in five eastern districts in Nghe An province, Vietnam were investigated in late 2004 for
food-borne trematodes and other helminth infections using duplicate Kato-Katz thick smears prepared from single stool samples.
Eggs of fish-borne trematodes and of Fasciolopsis buski were found in 0.6 and 0.7% of farmers, respectively. Infection prevalences
with soil-transmitted helminths (STHs), namely Ascaris lumbricoides, Trichuris trichiura and hookworm, were 34.8, 50.7 and
51.3%, respectively, and 81.8% were infected with at least one of the three STHs. While A. lumbricoides and T. trichiura were
more prevalent in the eastern districts compared to the more western districts, the opposite was true for hookworm infections.
The widespread prevalence of STH infections in fish farmers suggests that control of these infections in school-age children only
may be inadequate. Identification of the human behavioural factors and environmental features responsible for the distribution and
frequency of STHs among adults is needed as well as a sensitive diagnostic test of fish-borne trematodes at species level.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Food-borne trematodes; Soil-transmitted helminths; Ascaris lumbricoides; Trichuris trichiura; Hookworm; Fish farmers; Vietnam

Tháng Chín 22, 2017

Thanh Hoa Le,1 Nguyen Van De,2 Takeshi Agatsuma,3 David Blair,4* Jozef Vercruysse,5
Pierre Dorny,5 Thanh Giang Thi Nguyen,1 and Donald P. McManus6
Department of Immunology, Institute of Biotechnology, Hanoi, Vietnam1; Faculty of Parasitology, Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam2; Department of Environmental Health Sciences, Kochi Medical School, Kochi, Japan3; School of Tropical Biology, James Cook University, Townsville, QLD 4811, Australia4; Faculty of Veterinary Medicine, Ghent University,
Ghent, Belgium5; and Queensland Institute of Medical Research, Brisbane, QLD 4006, Australia6

Received 5 June 2006/Returned for modification 6 July 2006/Accepted 9 October 2006

Tháng Chín 11, 2017

Paragonimus heterotremus Chen and Hsia (1964), and paragonimiasis caused by this species is a newly detected disease in
Vietnam. Twelve samples of Paragonimus (Platyhelminthes: Trematoda: Digenea: Paragonimidae) from different life-stages (eggs,
miracidia, metacercariae, adults from natural and experimental hosts) and host species (crab, dog, cat and human) were collected
in different geographical locations in Vietnam. DNA sequences were obtained from each for partial mitochondrial cytochrome c
oxidase subunit 1 (cox1) (387 bp) and the entire second ribosomal internal transcribed spacer (ITS-2) (361 bp). The ITS-2 sequences
were identical among all specimens, including those previously reported in GenBank. For cox1, there were sequence differences
between specimens from Vietnam (four provinces, different locations) and those from Guangxi (China) and Saraburi (Thailand).
Phylogenetic trees inferred from cox1 and ITS-2 sequences using sequence data for 15 P. heterotremus and for other Paragonimus
spp. revealed that all P. heterotremus originating from Vietnam, Thailand and China form a distinct group. This information also
confirms the identity of the Vietnamese specimens as P. heterotremus.
© 2006 Published by Elsevier B.V.
Keywords: Mitochondrial DNA; Paragonimus heterotremus; Cytochrome c oxidase subunit 1 (cox1); Internal transcribed spacer-2 (ITS-2); Metacercariae; Identification; Phylogeny

Tháng Chín 11, 2017

Thanh Hoa Le a,e,¤, Nguyen Van De b, David Blair c, Paiboon Sithithaworn d,
Donald P. McManus e
” We report a single, one-step PCR approach for detection and discrimination of Clonorchis sinensis and Opisthorchis viverrini in diVerent lifestage forms (adults, metacercariae, and eggs) from Wsh intermediate hosts and from infected patients. Primers designed for species-speciWc PCR,
amplifying portions of the mitochondrial (mt) genome, were also suitable for a multiplex PCR. The latter was a single, one-step reaction under
high stringency conditions, using simultaneously 2 pairs of primers (1 pair for C. sinensis—product size 612bp, and 1 pair for O. viverrini—
product size 1357 bp). Assays using serially diluted templates demonstrated that as little as 0.78ng of genomic DNA of either species could yield
amplicons. Genomic DNA extracted from diVerent life-stage forms including adult worms (of both species), eggs (of O. viverrini), eggs possibly
of several trematode species (collected from patients infected with C. sinensis in Vietnam) and mixed metacercariae of common trematodes (collected from Wshes in the C. sinensis endemic areas), yielded speciWc bands of the correct size and their identity was conWrmed by sequence analysis. The multiplex PCR approach described here proved to be a species-speciWc, sensitive and fast tool for accurate diagnosis of clonorchiasis”
and/or opisthorchiasis, permitting the detection of their metacercariae in infected Wshes or adult/eggs from patients in endemic areas.
 2005 Elsevier Inc. All rights reserved.