Seroprevalence of Tissue and Luminal Helminths among Patients in Hanoi Medical University Hospital, Vietnam, 2018

A serological survey was performed using ELISA to estimate the prevalence of tissue and luminal helminthic infections among hospital patients in Hanoi region, Vietnam. An overall seroprevalence of tissue and luminal helminthiases was 64.0% (95% CI 61.2-66.8) among 1,120 patients who visited Hanoi Medical University Hospital, Vietnam in 2018. The highest seroprevalence was observed against Toxocara spp. (59.0%), followed by Strongyloides stercoralis (46.3%), Gnathostoma spp. (25.5%), cysticercus (12.8%), Angiostrongylus cantonensis (10.5%), Fasciola spp. (11.1%), and Clonorchis sinensis (8.7%). Mono-infection by one species (11.1%) was lower than multiple infections (53.0%) (P0.05). Children (<15 years) revealed lower seroprevalence (34.0%) than adults (68.4%), and the age group 51-70 years revealed the highest seroprevalence (76.0%). Among the seropositive patients, eosinophilia (≥8.0%) was noted in 80.2%. The present results suggested active transmission of various tissue and luminal helminths among people in Hanoi, Vietnam.

Two Human Cases of Echinococcus ortleppi Infection in the Lung and Heart in Vietnam

This is a report of 2 cases of human hydatidosis caused by Echinococcus ortleppi in Vietnam. The patients were a 12-year-old male (case 1) having a cyst of 10.0×9.0 cm size in the lung and a 50-year-old female with a 3.0×3.3 cm-sized cyst in the heart. Eosinophilia was 33.7% in the male and 45.8% in the female patient. C-reactive protein was increased to 16.5 mg/L in the male and 18.2 mg/L in the female. Both patients were positive for ELISA at OD=2.5 and 3.1, respectively. Echinococcus protoscolices were collected from the cysts by amniocentesis and surgery. The protoscolices were identified as E. ortleppi by morphology and analysis of mitochondrial NADH dehydrogenase 1 (nad1) gene sequence. Both patients were cured by surgical resection of the hydatid cyst combined with albendazole medication. The E. ortleppi infection in lung is the second report, and the other in the heart is the first in Vietnam.

Powerful Homeostatic Control of Oligodendroglial Lineage by PDGFRα in Adult Brain.

Oligodendrocyte progenitor cells (OPCs) are widely distributed cells of ramified morphology in adult brain that express PDGFRα and NG2. They retain mitotic activities in adulthood and contribute to oligodendrogenesis and myelin turnover; however, the regulatory mechanisms of their cell dynamics in adult brain largely remain unknown. Here, we found that global Pdgfra inactivation in adult mice rapidly led to elimination of OPCs due to synchronous maturation toward oligodendrocytes. Surprisingly, OPC densities were robustly reconstituted by the active expansion of Nestin+ immature cells activated in meninges and brain parenchyma, as well as a few OPCs that escaped from Pdgfra inactivation. The multipotent immature cells were induced in the meninges of Pdgfra-inactivated mice, but not of control mice. Our findings revealed powerful homeostatic control of adult OPCs, engaging dual cellular sources of adult OPC formation. These properties of the adult oligodendrocyte lineage and the alternative OPC source may be exploited in regenerative medicine.

Distribution Status of Hybrid Types in Large Liver Flukes, Fasciola Species (Digenea: Fasciolidae), from Ruminants and Humans in Vietnam

The aim of this study is to delineate ‘admixed hybrid’ and ‘introgressive’ Fasciola genotypes present in the Fasciola population in Vietnam. Adult liver flukes collected from ruminants in 18 Provinces were morphologically sorted out by naked eyes for small (S), medium (M) and large (L) body shapes; and human samples (n=14) from patients. Nuclear ribosomal (rDNA) ITS1 and ITS2, and mitochondrial (mtDNA) nad1 markers were used for determination of their genetic status. Total 4,725 worm samples of ruminants were tentatively classified by their size: 6% (n=284) small (S)-, 13% (n=614) medium (M)-, and 81% (n=3,827) large (L)-forms. All the representative (n=120, as 40 each group) and 14 human specimens, possessed maternal mtDNA of only F. gigantica and none of F. hepatica. Paternally, all (100%) of the L-(n=40) and 77.5% (n=31) of the M-flukes had single F. gigantica rDNA indicating ‘pure’ F. gigantica. A majority (90%, n=36) of the S- and 15% (n=6) of the M-worms had single F. hepatica rDNA, indicating their introgressive; the rest (10%, n=4) of the S- and 7.5% (n=3) of the M-flukes had mixture of both F. gigantica and F. hepatica rDNAs, confirming their admixed hybrid genetic status. Fourteen human samples revealed 9 (64%) of pure F. gigantica, 3 (22%) of introgressive and 2 (14%) of admixed hybrid Fasciola spp. By the present study, it was confirmed that the small worms, which are morphologically identical with F. hepatica, are admixed and/or introgressive hybrids of Fasciola spp., and able to be the pathogens of human fascioliasis.

Prevalence of Soil-Transmitted Helminths and Molecular Clarification of Hookworm Species in Ethnic Ede Primary Schoolchildren in Dak Lak Province, Southern Vietnam

To know the infection status of helminths in primary schoolchildren of southern parts of Vietnam, we performed an epidemiological study in Krong Pac district, Dak Lak Province, Vietnam. A total of 1,206 stool specimens were collected from ethnic Ede schoolchildren in 4 primary schools in 2015 and examined by the Kato-Katz technique. In addition, stool cultures were done by the Harada-Mori method to obtain hookworm larvae and then to clarify the species of hookworms infected. The results showed that the helminth infection rate was 25.0%, including 2.0% Ascaris lumbricoides, 0.33% Trichuris trichiura, and 22.8% hookworm infections. The average intensity of infection was 102.0 eggs per gram of feces (EPG) for Ascaris, 36.0 EPG for Trichuris, and 218.0 EPG for hookworms. ITS1 gene sequences of the hookworm larvae were identical with those of Necator americanus (100% homology) reported in GenBank. It has been confirmed in this study that the hookworm, N. americanus, is a dominant helminth species infected in primary schoolchildren of a southern part of Vietnam. Public health attention is needed for control of hookworm infections among schoolchildren in surveyed areas of Vietnam.

A Case of Ocular Angiostrongyliasis with Molecular Identification of the Species in Vietnam

A 23-year-old female residing in a village of Cao Bang Province, North Vietnam, visited the Hospital of Hanoi Medical University in July 2013. She felt dim eyes and a bulge-sticking pain in her left eye for some days before visiting the hospital. In the hospital, a clinical examination, an eye endoscopy, and an operation were carried out. A nematode specimen was collected from the eye of this patient. The body of this worm was thin and long and measured 22.0x0.3 mm. It was morphologically suggested as an immature female worm of Angiostrongylus cantonensis. By a molecular method using 18S rRNA gene, this nematode was confirmed as A. cantonensis. This is the first molecular study for identification of A. cantonensis in Vietnam.

Current Status of Taeniasis and Cysticercosis in Vietnam

Several reports on taeniasis and cysticercosis in Vietnam show that they are distributed in over 50 of 63 provinces. In some endemic areas, the prevalence of taeniasis was 0.2-12.0% and that of cysticercosis was 1.0-7.2%. The major symptoms of taeniasis included fidgeted anus, proglottids moving out of the anus, and proglottids in the feces. Clinical manifestations of cysticercosis in humans included subcutaneous nodules, epileptic seizures, severe headach, impaired vision, and memory loss. The species identification of Taenia in Vietnam included Taenia asiatica, Taenia saginata, and Taenia solium based on combined morphology and molecular methods. Only T. solium caused cysticercosis in humans. Praziquantel was chosen for treatment of taeniasis and albendazole for treatment of cysticercosis. The infection rate of cysticercus cellulosae in pigs was 0.04% at Hanoi slaughterhouses, 0.03-0.31% at provincial slaughterhouses in the north, and 0.9% in provincial slaughterhouses in the southern region of Vietnam. The infection rate of cysticercus bovis in cattle was 0.03-2.17% at Hanoi slaughterhouses. Risk factors investigated with regard to transmission of Taenia suggested that consumption of raw meat (eating raw meat 4.5-74.3%), inadequate or absent meat inspection and control, poor sanitation in some endemic areas, and use of untreated human waste as a fertilizer for crops may play important roles in Vietnam, although this remains to be validated.

Molecular Diagnosis of an Ocular Toxocariasis Patient in Vietnam

An ocular Toxocara canis infection is reported for the first time in Vietnam. A 34-year-old man residing in a village of Son La Province, North Vietnam, visited the National Eye Hospital (NEH) in August 2011. He felt a bulge-sticking pain in his left eye and loss of vision occurred over 3 months before visiting the hospital. The eye examination in the hospital showed damage of the left eye, red eye, retinal fibrosis, retinal detachment, inflammation of the eye tissues, retinal granulomas, and a parasitic cyst inside. A larva of Toxocara was collected with the cyst by a medical doctor by surgery. Comparison of 264 nucleotides of internal transcribed spacer 2 (ITS2) of ribosomal DNA was done between our Vietnamese Toxocara canis and other Toxocara geographical isolates, including Chinese T. canis, Japanese T. canis, Sri Lankan T. canis, and Iranian T. canis. The nucleotide homology was 97-99%, when our T. canis was compared with geographical isolates. Identification of a T. canis infection in the eye by a molecular method was performed for the first time in Vietnam.

The first human case of Thelazia callipaeda infection in Vietnam.

A 26-year-old man residing in a village of Thai Nguyen Province, North Vietnam, visited the Thai Nguyen Provincial Hospital in July 2008. He felt a bulge-sticking pain in his left eye and extracted 5 small nematode worms by himself half a day before visiting the hospital. Two more worms were extracted from his left eye by a medical doctor, and they were morphologically observed and genetically analyzed on the mitochondrial cytochrome c oxidase 1 gene. The worms were 1 male and 1 female, and genetically identical with those of Thelazia callipaeda. By the present study, the presence of human T. callipaeda infection is first reported in Vietnam.

The current status of opisthorchiasis and clonorchiasis in the Mekong Basin.

This review highlights the current status and control of liver fluke infections in the Mekong Basin countries where Opisthorchis and Clonorchis are highly endemic. Updated data on prevalence and distribution have been summarized from presentations in the "96 Years of Opisthorchiasis. International Congress of Liver Flukes". It is disturbing that despite treatment and control programs have been in place for decades, all countries of the Lower Mekong Basin are still highly endemic with O. viverrini and/or C. sinensis as well as alarmingly high levels of CCA incidence. A common pattern that is emerging in each country is the difference in transmission of O. viverrini between lowlands which have high prevalence versus highlands which have low prevalence. This seems to be associated with wetlands, flooding patterns and human movement and settlement. A more concerted effort from all community, educational, public health and government sectors is necessary to successfully combat this fatal liver disease of the poor.

The First Human Case of Thelazia callipaeda Infection in Vietnam

A 26-year-old man residing in a village of Thai Nguyen Province, North Vietnam, visited the Thai Nguyen Provincial Hospital in July 2008. He felt a bulge-sticking pain in his left eye and extracted 5 small nematode worms by himself half a day before visiting the hospital. Two more worms were extracted from his left eye by a medical doctor, and they were morphologically observed and genetically analyzed on the mitochondrial cytochrome c oxidase 1 gene. The worms were 1 male and 1 female, and genetically identical with those of Thelazia callipaeda. By the present study, the presence of human T. callipaeda infection is first reported in Vietnam.

Foodborne Trematode Metacercariae in Fish from Northern Vietnam and Their Adults Recovered from Experimental Hamsters

The prevalence of foodborne trematode (FBT) metacercariae was investigated in fish from 2 localities of northern Vietnam in 2004-2005. Freshwater fish (9 species) were collected from local markets in Hanoi City (n=76) and Nam Dinh Province (n=79), and were examined for FBT metacercariae using the artificial digestion technique. Adult flukes were obtained from hamsters experimentally infected with the metacercariae at day 8 post-infection. Three (Haplorchis pumilio, Centrocestus formosanus, and Procerovum varium) and 6 (Haplorchis taichui, H. pumilio, C. formosanus, P. varium, Stellantchasmus falcatus, and Heterophyopsis continua) species of FBT metacercariae were detected in the 2 regions, respectively. Overall, among the positive fish species, H. pumilio metacercariae were detected in 104 (80.0%) of 130 fish examined (metacercarial density per infected fish; 64.2). C. formosanus metacercariae were found in 37 (40.2%) of 92 fish (metacercarial density; 14.7). P. varium metacercariae were detected in 19 (63.3%) of 30 fish (Anabas testudineus and Mugil cephalus) (metacercarial density; 247.7). S. falcatus metacercariae were found in all 10 M. cephalus examined (metacercarial density; 84.4). H. continua metacercariae (2 in number) were detected in 1 fish of Coilia lindmani. Morphologic characteristics of the FBT metacercariae and their experimentally obtained adults were described. The results have demonstrated that various FBT species are prevalent in northen parts of Vietnam.

An Outbreak of Trichinosis with Molecular Identification of Trichinella sp. in Vietnam

The 5th outbreak of trichinosis occurred in a mountainous area of North Vietnam in 2012, involving 24 patients among 27 people who consumed raw pork together. Six of these patients visited several hospitals in Hanoi for treatment. Similar clinical symptoms appeared in these patients within 5-8 days after eating infected raw pork, which consisted of fever, muscle pain, difficult moving, edema, difficult swallowing, and difficult breathing. ELISA revealed all (6/6) positive reactions against Trichinella spiralis antigen and all cases showed positive biopsy results for Trichinella sp. larvae in the muscle. The larvae detected in the patients were identified as T. spiralis (Vietnamese strain) by the molecular analysis of the mitochondrial cytochrome c oxidase subunit III (cox3) gene.

Dirofilaria repens in Vietnam: Detection of 10 Eye and Subcutaneous Tissue Infection Cases Identified by Morphology and Molecular Methods

From 2006 to 2010, hospitals in Hanoi treated 10 human patients for dirofilariasis. The worms were collected from parasitic places, and identification of the species was completed by morphology and molecular methods. Ten parasites were recovered either from the conjunctiva (n=9) or subcutaneous tissue (n=1). The parasites were 4.0-12.5 cm in length and 0.5-0.6 mm in width. Morphological observations suggested all parasites as Dirofilaria repens. Three of the 10 parasites (1 from subcutaneous tissue and 2 from eyes) were used for molecular confirmation of the species identification. A portion of the mitochondrial cox1 (461 bp) was amplified and sequenced. Nucleotide and amino acid homologies were 95% and 99-100%, respectively, when compared with D. repens (Italian origin, GenBank AJ271614; DQ358814). This is the first report of eye dirofilariasis and the second report of subcutaneous tissue dirofilariasis due to D. repens in Vietnam.

Echinostoma revolutum: metacercariae in Filopaludina snails from Nam Dinh Province, Vietnam, and adults from experimental hamsters.

We detected metacercariae of Echinostoma revolutum in Filopaludina sp. snails purchased from a local market in Nam Dinh Province for the first time in Vietnam. Adult flukes were harvested from experimentally infected hamsters at days 14 and 17 post-infection. The metacercariae were round, 170-190 µm (n = 15) in diameter, with a cyst wall thickness of about 12 µm. A total of 37 collar spines were arranged around the head collar, and large excretory granules were seen in 2 canals of the excretory bladder. The 14-day old adult flukes were elongated, ventrally curved, and 5.0-7.2 × 0.8-1.3 mm (n = 20). The head collar had a total of 37 collar spines arranged in 2 alternating rows, including 5 corner spines on each side. The cirrus sac contained a saccular seminal vesicle, a prostatic gland, and an unarmed cirrus. Two tandem testes were smooth or slightly lobed. Eggs were ovoid to elliptical, 110-118 × 70-75 µm. These morphological characters were similar to those of E. revolutum and E. jurini. We tentatively identified it as E. revolutum because the validity of E. jurini remains to be elucidated. The taxonomic relationship of E. revolutum and E. jurini is discussed.

Echinostoma revolutum: Metacercariae in Filopaludina Snails from Nam Dinh Province, Vietnam, and Adults from Experimental Hamsters

We detected metacercariae of Echinostoma revolutum in Filopaludina sp. snails purchased from a local market in Nam Dinh Province for the first time in Vietnam. Adult flukes were harvested from experimentally infected hamsters at days 14 and 17 post-infection. The metacercariae were round, 170-190 microm (n=15) in diameter, with a cyst wall thickness of about 12 microm. A total of 37 collar spines were arranged around the head collar, and large excretory granules were seen in 2 canals of the excretory bladder. The 14-day old adult flukes were elongated, ventrally curved, and 5.0-7.2x0.8-1.3 mm (n=20). The head collar had a total of 37 collar spines arranged in 2 alternating rows, including 5 corner spines on each side. The cirrus sac contained a saccular seminal vesicle, a prostatic gland, and an unarmed cirrus. Two tandem testes were smooth or slightly lobed. Eggs were ovoid to elliptical, 110-118x70-75 microm. These morphological characters were similar to those of E. revolutum and E. jurini. We tentatively identified it as E. revolutum because the validity of E. jurini remains to be elucidated. The taxonomic relationship of E. revolutum and E. jurini is discussed.

Occurrence and species distribution of fishborne zoonotic trematodes in wastewater-fed aquaculture in northern Vietnam.

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 1200 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 non-wastewater 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.

Situation helminthiasis in two mountain points of Hoa Binh and Son La provinces

Toan Son commune (Da Bac district, Hoa binh province) and Quy Huong commune (Moc Chau district, Son la province) are remote mountainous areas. Methods as interview, stool examination by Kato technique, sputum examination and snail examination by direct technique, crab muscle digestion were used in the study. Results of the study, showed that rate of people having habit of eating raw crab was 73.0% in Toan Son and 72.2% in Quy Huong; paragonimiasis rates were 3.3-11.3% and 3.4-15.7%, Ascaris infection rates was 52.3% and 50.0%, hookworm infection rates was 33.0% and 35.9%, Trichuris infection rates was 29.7% and 4.3%, clonorchiasis infection rate was 0.7 % (in Toan Son only), Taenia infection rates was 0.4% and 0.3%.In these communes, dogs, crabs and snails were also infected with paragonimus.

Identification of adult worm of human small liver fluke in Nghe An and Dong Nai province

Since 2002, adult worms of human small liver fluke in some provinces were identified by morphology and confirmed by molecular method as Clonorchis sinensis in Thanh Hoa, Ninh Binh, Nam Dinh and Bac Giang province; Opisthorchis viverrini in Phu Yen and Binh Dinh province. This study, using polymerase chain reaction (PCR), a portion of the cytochrome oxidase 1 (410 nucleotide and 136 amino acid) of mitochondrial genome of adult worms of small liver fluke from human in Nghe An (CsNA) and Dong Nai (CsDN) province were amplified. The nucleotide and amino acid of these sequences was comparatively analyzed with the known Clonorchis sinensis (Nam Dinh strain). The analysis revealed that the Nghe An Clonorchis sp and Dong Nai Clonorchis sp (in human) were homology (99.5 - 99.8% nucleotide) and similar (100% amino acid) to the Nam Dinh Clonorchis sinensis (identification was done). Thus, the Nghe An and Dong Nai Clonorchis sp were identified as Clonorchis sinensis in Opisthorchiidae family, Clonorchis genus.

Identification of adult worm of human small liver fluke in Hiep Hoa district, Bac Giang province by molecular method

Using polymerase chain reaction (PCR), a portion of the cytochrome oxidase 1 (446 nucleotide and 148 amino acid) of mitochondrial genome of adult worm of small liver fluke from human in Hiep Hoa district, Bac Giang (CsNgBG) province was amplified. The nucleotide and amino acid of these sequences were comparatively analyzed with the known Clonorchis sinensis. The analysis revealed that the Bac Giang Clonorchis sp (in human) was similar (100% nucleotide and amino acid) to the Nam Dinh Clonorchis sinensis (identification was done); 99.6% (nucleotide) and 100% (amino acid) homology to the C.sinensis of Chinese strain (CsCN-Gen Bank AF 184619) and Korean strain (CsKor-Gen Bank AF 181889). Thus, the Bac Giang Clonorchis sp is identified as Clonorchis sinensis in Opisthorchidae family, Clonorchis genus. Phylogenetic analysis uniquely placed the Bac Giang Clonorchis sinensis to the group of Chinese and Korean Clonorchis sinensis.