Effect of control strategies on prevalence, incidence and re-infection of clonorchiasis in endemic areas of China.

BACKGROUND: A pilot clonorchiasis control project was implemented to evaluate the efficacies of various chemotherapy strategies on prevalence, incidence and re-infection in Heilongjiang Province, China. METHODS AND FINDINGS: Seven intervention groups (14,139 residents, about 2000 in each group) in heavily or moderately endemic areas were subjected to repeated praziquantel administration from 2001 to 2004. In the selective chemotherapy groups, residents were examined for fecal eggs, and those who tested positive were treated with three doses of 25 mg/kg praziquantel at 5-hour-intervals in one day. However, all residents were treated in the mass chemotherapy groups. In heavily endemic areas, two mass treatments of all residents in 2001 and 2003 reduced the prevalence from 69.5% to 18.8%, while four annual mass treatments reduced the prevalence from 48.0% in 2001 to 8.4% in 2004. Selective annual treatments for egg-positive subjects reduced the egg-positive rates from 54.9% in 2001 to 15.0% in 2004 or from 73.2% in 2001 to 12.3% in 2004. Selective treatments every 6 months significantly reduced the prevalence from 59.5% in 2001 to 7.5% in 2004. All of the repeated treatments reduced EPG (eggs per gram of feces) significantly. The annual mass treatment and selective treatment every 6 months produced lower prevalence and re-infection rates and higher egg reduction rate than annual selective treatments did. In the moderate endemic areas, egg positive rates were 24.8% and 29.7% in 2001 but were 1.9% and 1.3% after 2 or 3 selective treatments. The prevalence, incidence, re-infection rates in a moderately endemic area were significantly lower than those of heavy endemic areas. CONCLUSIONS: Repeated mass treatment or selective treatment with praziquantel every 6 to 12 months is highly effective for clonorchiasis control in heavily endemic areas. In contrast, one or two selective treatments with health education is effective in moderately endemic areas.

PwRn1, a novel Ty3/gypsy-like retrotransposon of Paragonimus westermani: molecular characters and its differentially preserved mobile potential according to host chromosomal polyploidy.

BACKGROUND: Retrotransposons have been known to involve in the remodeling and evolution of host genome. These reverse transcribing elements, which show a complex evolutionary pathway with diverse intermediate forms, have been comprehensively analyzed from a wide range of host genomes, while the information remains limited to only a few species in the phylum Platyhelminthes. RESULTS: A LTR retrotransposon and its homologs with a strong phylogenetic affinity toward CsRn1 of Clonorchis sinensis were isolated from a trematode parasite Paragonimus westermani via a degenerate PCR method and from an insect species Anopheles gambiae by in silico analysis of the whole mosquito genome, respectively. These elements, designated PwRn1 and AgCR-1 - AgCR-14 conserved unique features including a t-RNATrp primer binding site and the unusual CHCC signature of Gag proteins. Their flanking LTRs displayed >97% nucleotide identities and thus, these elements were likely to have expanded recently in the trematode and insect genomes. They evolved heterogeneous expression strategies: a single fused ORF, two separate ORFs with an identical reading frame and two ORFs overlapped by -1 frameshifting. Phylogenetic analyses suggested that the elements with the separate ORFs had evolved from an ancestral form(s) with the overlapped ORFs. The mobile potential of PwRn1 was likely to be maintained differentially in association with the karyotype of host genomes, as was examined by the presence/absence of intergenomic polymorphism and mRNA transcripts. CONCLUSION: Our results on the structural diversity of CsRn1-like elements can provide a molecular tool to dissect a more detailed evolutionary episode of LTR retrotransposons. The PwRn1-associated genomic polymorphism, which is substantial in diploids, will also be informative in addressing genomic diversification following inter-/intra-specific hybridization in P. westermani populations.

Critical roles for excretory-secretory cysteine proteases during tissue invasion of Paragonimus westermani newly excysted metacercariae.

Paragonimus westermani is a trematode parasite, which causes pulmonary and/or extrapulmonary granulomatous disease in humans. Successful invasion of the host tissue is critical for the survival of this tissue-invasive parasite. The enzymatic hydrolysis of host proteins is clearly a prerequisite of this process. In this study, we have investigated the functional roles of the excretory-secretory cysteine proteases of P. westermani newly excysted metacercariae (PwNEM) in tissue invasion. The 27 and 28 kDa enzymes (PwMc27 and PwMc28) purified from PwNEM excretory-secretory products (ESP), preferentially degraded fibrillar proteins, but not globular proteins. PwMc28 significantly facilitated the invasion of PwNEM into mouse peritoneum, whereas a diffusible cysteine protease inhibitor, trans-epoxysuccinyl-L-leuciloamido-(4-guanidino) butane (E-64) inhibited this process dose-dependently. Two distinct isoforms of PwMc28 (PwMc28a and PwMc28b), which exhibited two amino acid differences in their mature domains, were identified by tandem mass spectrometry and sequence analysis. Both enzymes were localized at the tegument on the anterior border and on the oral sucker, which suggests excretion-secretion via exocytosis or via the excretory canal network. The mRNA transcripts of PwMc28a and b were expressed abundantly during the active invasion/migration through the host's tissues, suggesting their relevant function to tissue invasion/migration in the definitive host.

Identification of immunodominant excretory-secretory cysteine proteases of adult Paragonimus westermani by proteome analysis.

Paragonimus westermani causes inflammatory lung disease in humans. The parasite excretes a host of biologically active molecules, which are thought to be involved in pathophysiological and immunological events during infection. Analyses of the 2-DE protein profiles of the excretory-secretory products (ESP) of adult P. westermani revealed approximately 147 protein spots, at least 15 of which were identified as cysteine proteases (CPs), at pHs between 4.5 and 8.5, and molecular weights (MWs) between 27 and 35 kDa. An additional three CPs (designated as PwCP-3, -8 and -11) were newly recognized by TOF/TOF MS. Their molecular biological information, which shared a high level sequence homology, was elucidated. The majority of the CPs reacted strongly with sera from paragonimiasis patients. When we observed the chronological changes in the antibody responses of the respective CPs against canine sera collected serially at 1, 3, 5, 7, 11 and 14 wk after experimental infection, these molecules exhibited a multiplicity of distinct immune recognition patterns. Our results clearly showed that P. westermani adult ESP were principally composed of excretory-secretory CPs, and that these CPs may exert effects not only on host tissue degradation and nutrient uptake, but also on the immune-regulating cells via synergistic and independent interactions.

A seroepidemiological survey of Taenia solium cysticercosis in Nabo, Guangxi Zhuang Autonomous Region, China.

We have observed the seropositive rate of Taenia solium cysticercosis in residents at Nabo Village, Tiandong County, Guangxi Zhuang Autonomous Region, China by enzyme linked immunosorbent assay. The village had been found to be a relatively high endemic area of porcine cysticercosis among roaming pigs. Of 202 persons examined four males aged 15, 25, 35 and 41 year-old exhibited absorbance (abs) at 0.18, 0.20, 0.35 and 0.55, respectively. In addition, two females whose ages were 35 and 39 years revealed specific antibody levels of abs 0.26 and 0.41 in their sera. Overall positive rate among the people was 2.97%. All of these persons agreed that they had ingested the pork infected with T. solium metacestode (TsM), while history of proglottid discharge was not noticed from all of them. Three males and one female complained of intermittent headache. Our findings reinforced not only that the prevalence of cysticercosis might be related with roaming pigs infected with TsM but also that behavioral and environmental practices in local community constituted risk factors for transmission of the infection.

Taenia solium: identification of specific antibody binding regions of metacestode 10-kDa protein.

Taenia solium neurocysticercosis (NCC) represents one of the major public health problems associated with several neurological manifestations worldwide. We previously identified a recombinant 10-kDa protein of T. solium metacestode (CyDA) specific to active NCC. Immunoblottings with sera from active NCC patients and from animals experimentally infected with larval T. solium (pig), T. saginata (pig), T. asiatica (pig), and T. crassiceps (mouse) strongly recognized CyDA, while sera from patients infected only with adult worms did not. Mapping of antigenic sites using deletion mutants revealed that amino acids (aa) residues 30-34, Asn-Met-Thr-Val-Met (NMTVM), reacted only with sera from active stage T. solium cysticercosis cases. Recognition of CyDA aa 30-34 resided almost exclusively in the IgG4 isotype. Competitive immunoprecipitation with synthetic peptides confirmed the specificity of anti-sera for this penta-peptide. These results demonstrated that aa residues NMTVM in CyDA comprise the core sequence for an active stage NCC-related antigenic determinant. ligand binding protein, HLBP; Cyst fluid, CF; Pooled serum of 10 active NCC patients, serum-pool.

Excretory bladder: the source of cysteine proteases in Paragonimus westermani metacercariae.

The cysteine proteases of Paragonimus westermani metacercariae are involved in metacercarial excystment, host immune modulation, and possibly in tissue penetration. In order to clarify the origin of the enzymes, 28 and 27 kDa cysteine proteases in metacercarial excretory-secretory products were purified through the FPLC system using Mono Q column chromatography. The polyclonal antibodies to the enzymes were produced in BALB/c mice. Immunolocalization studies revealed that both cysteine proteases were distributed at the linings of excretory bladder and excretory concretions of the metacercariae. It was suggested that the excretory epithelium of P. westermani undertake the secretory function of metacercarial cysteine proteases, in addition to its role as a route for eliminating waste products.

Paragonimus westermani: molecular cloning, expression, and characterization of a recombinant yolk ferritin.

Ferritin is an intracellular protein involved in iron metabolism. A cDNA PwYF-1 cloned from the adult Paragonimus westermani cDNA library encoded a putative polypeptide of 216 amino acids homologous with ferritins of vertebrates and invertebrates. Febinding motifs identified in PwYF-1 polypeptide were conserved and predicted to form a ferroxidase center. PwYF-1 polypeptide contained an extended peptide of 45 amino acids at its C-terminus. Recombinant PwYF-1 protein, expressed and purified from Escherichia coli, showed iron-uptake ability and ferroxidase activity. Ferroxidase activity of recombinant PwYF-1 protein was reactivated by secondary addition of apotransferrin to assay mixture. Mouse immune serum raised against the recombinant PwYF-1 protein recognized specifically 24 kDa protein from adult P. westermani lysate. PwYF-1 protein was localized to vitelline follicles and the eggs of P. westermani. Collectively, PwYF-1 protein was identified as a P. westermani yolk ferritin.

Antigenic protein fractions reacting with sera of sparganosis patients.

To observe the antigenic protein fractions in saline extract of Spirometra mansoni plerocercoid (sparganum), the crude extract was separated in reducing conditions of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The proteins, transferred by electrophoresis to nitrocellulose paper, were reacted with sera from 15 surgically confirmed sparganosis and 24 cysticercosis patients for immunoblotting. Out of 30 identified protein bands in the extract, bands of 29 and 36 kilodaltons (kDa) were the strongest and the most frequently reacting with specific antibody (IgG) in sparganosis sera. Bands of higher molecular weight also reacted with the sera but their frequency of reactions was lower. Sera of cysticercosis reacted with different protein bands in saline extract of sparganum, but the cross reactions were observed in strong antigenic bands of 29 and 36 kDa.

Biochemical properties of a purified protein in cystic fluid of Taenia solium metacestodes.

By affinity chromatography using a monoclonal antibody as ligand, Kim et al. (1986) purified a protein fraction in cystic fluid of Taenia solium metacestodes (CF). In this study, the biochemical properties of the purified protein were characterized. Discontinuous-polyacrylamide gel electrophoresis (disc-PAGE) of the protein at 4.5~10% separating gel concentration showed its molecular weight (MW) to be 150 kilodalton(kDa) in non-denatured state, while denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that it was composed of 3 different subunits with respective MW of 15, 10 and 7 kDa. Subunit of 7 kDa was shown to be linked to other subunits by disulfide bonds. Isoelectric point of the protein was pH 6.8. The protein was relatively heat-stable for immunologic analysis. These properties indicated that the protein, comprising about 70% of total content in CF, had similar biochemical characters with antigen B of Oriol et al.(1971) in hydatid cyst fluid (HF)

Intracranial synthesis of specific IgG antibody in cerebrospinal fluid of neurocysticercosis patients.

To determine the source of Cysticercus-specific IgG antibody in cerebro-spinal fluid(CSF), paired samples of serum and CSF were collected from confirmed neurocysticercosis, other neurologic diseases and normal control. The antibody levels in serum and CSF were measured by enzyme-linked immunosorbent assay (ELISA). With the measurement of total protein, albumin and IgG concentration in serum and CSF, the contribution of IgG in CSF were calculated in transudation, exudation and intracranial synthesis using the formula of Tourtellotte and Ma (1978). Mean concentrations of total protein, albumin, IgG and proportional IgG levels in CSF by transudation, exudation and intracranial synthesis were elevated in neurocysticercosis. But only the intracranial synthesis of IgG showed a statistically significant correlation with the specific IgG antibody levels in CSF. In CSF from lateral ventricle in the 4th ventricular neurocysticercosis, the protein concentrations were normal and the specific antibody levels were negative. However, in consecutively secured lumbar CSF from the same patients, the former were increased and the latter were positive. These results indicated that, in neurocysticercosis, the specific IgG antibody in CSF was a local product of intracranial synthesis.

Comparative evaluation of indirect immunofluorescent antibody test with enzyme-linked immunosorbent assay in serodiagnosis of human neurocysticercosis.

The applicability of indirect immunofluorescent antibody test (IFAT) was compared with enzyme-linked immunosorbent assay (ELISA) in sera from 163 cases of confirmed neurocysticercosis, 101 other neurologic and parasitic diseases and 100 normal controls. As antigen, frozen sections of a Taenia solium metacestode from a human brain was used in IFAT and cystic fluid was used in ELISA. For the detection of specific IgG antibody, IFAT was equally sensitive (89. 6%) and specific (85. l%) as ELISA. The antibody titers by IFAT were correspondingly increased with mean absorbance of ELISA. The corresponding rate of positivity in the two techniques was 90.8%. Except for the difficulty in detecting antibodies in cerebrospinal fluid (CSF), IFAT was concluded to be very useful for the serodiagnosis of human neurocysticercosis.

Analysis of antigen specificity using monoclonal and polyclonal antibodies to Cysticercus cellulosae by enzyme-linked immunoelectrotransfer blot technique.

To analyse the antigen specificity of patients sera from 24 confirmed neurocysticercosis and a monoclonal antibody, SDS-PAGE using 10-15% linear gradient gel and EITB were done. Cystic fluid, saline extracts of scolex and of whole worm of C. cellulosae, saline extracts of sparganum, hydatid cyst fluid, saline extracts of Fasciola, Clonorchis and Paragonimus were used as antigen. Of protein bands in cystic fluid of C. cellulosae, patient sera reacted frequently to bands of 152, 94, 64, 48, 24, 15, 10 and 7 kDa proteins. To saline extracts of scolex and whole worm of C. cellulosae, patients sera reacted frequently to 94, 64, 52, 39, 34, 15 and 10 kDa bands. Two bands in sparganum extract (130 and 64 kDa) and two bands in hydatid cyst fluid (52 and 27 kDa) were cross-reacting bands with sera from cysticercosis patient. Saline extracts of Fasciola, Clonorchis and Paragonimus did not exhibit cross-reacting bands. Monoclonal antibody to cystic fluid of C. cellulosae was found to react with low molecular weight proteins of 15, 10 and 7 kDa.

Purification of cystic fluid antigen of Taenia solium metacestodes by affinity chromatography using monoclonal antibody and its antigenic characterization.

This study was undertaken to purify cystic fluid (CF) antigen of Taenia solium metacestodes by affinity chromatography using specific monoclonal antibody (McAb) and to characterize the antigenicity of the purified antigen. The hybridoma cell lines, prepared by fusion between mouse plasmacytoma and spleen cells from BALB/c mice immunized with CF, secrected antibodies reacting to various helminthic antigens. Majority of cell lines reacted to CF only but some also reacted to parenchymal antigen of T. solium metacestodes, adult T. saginata, sparganum, hydatid cystic fluid, Paragonimus westermani and Clonorchis sinensis, either in combination with CF, other antigens or independently. Cloned cells derived from monoclonal lines also produced antibodies reacting either to CF only or to other helminthes in combination or independently. These results indicated that CF of T. solium metacestodes contained proteins which possessed antigenic determinants not only specific to CF but also cross reactive with the afore-mentioned helminthes. CF of T. solium metacestodes was purified by affinity chromatography using the McAb which reacted to CF and parenchymal antigens. The affinity-purified antigen(A-Ag) and unbound pool(U-Ag) were separated. A-Ag showed 2 protein bands by disc-PAGE whereas CF exhibited 6 bands and U-Ag consisted of all bands CF had. The diagnostic significance of A-Ag was evaluated by ELISA in human neurocysticercosis and other helminthic and neurologic diseases. By A-Ag, the levels of the specific IgG antibody, as shown by absorbance in sera and CSF, were lower than those of CF and U-Ag. Accordingly, the sensitiviy was about 70 % of CF and U-Ag. However, the nonspecific positive reactions to CF and U-Ag, observed in sparganosis, T. saginata infection and paragonimiasis did not occur when A-Ag was used. These results indicated that the affinity-purified A-Ag had the higher specificity but the lower sensitivity as a diagnostic antigen in cysticercosis, probably because it only detected a single or limited numbers of monospecific antibodies among the diverse polyclonal antibodies produced in the patients with neurocysticercosis.

Serologic follow-up study in neurocysticercosis patients by ELISA after praziquantel treatment.

/A total of 69 patients of confirmed neurocysticercosis was followed serologically by ELISA up to 22 months after praziquantel treatment. The intervals and numbers of follow-up were variable by patients. Serially collected samples of serum and CSF were examined simultaneously for their specific IgG antibody levels by ELISA, using cystic fluid, saline extracts of bladder wall and scolex as antigen. Within 4 months after praziquantel treatment, the antibody levels were elevated temporarily in both serum and CSF in most patients. In some cases antibody levels exhibited steady declining tendency after the treatment. Concomitant administration of dexamethasone appeared to suppress the elevation of antibody levels. The rate of mean absorbance of antibody changed more in serum than in CSF. The rate of elevation was greater in antibodies to parenchymal antigens than that to cystic fluid, but absolute difference of antibody levels was greater in anitbody to cystic fluid. Previously negative samples for IgG antibody may become positive after praziquantel treatment, which could be used as a complementary tool(provocation test) in serodiagnosis. One month was considered to be sufficient interval for the follow-up test for that purpose. In the follow-up of up to 22 months, only few cases of chronic neurocysticercosis showed declining tendency of IgG antibody levels below negative range. During acute encephalitic attacks in chronic patients, IgG antibody to parenchymal antigen were elevated in CSF temporarily. These results indicated that serologic follow-up of every year was recommendable to differentiate the cured patients from chronic patients with slowly calcifying lesions.

Evaluation of enzyme-linked immunosorbent assay in serological diagnosis of human neurocysticercosis using paired samples of serum and cerebrospinal fluid.

The applicability of micro-ELISA was evaluatd in human neuro-cysticercosis using paired samples of serum and CSF. A total of 355 cases who were mostly neurologic patients was subjected. Cystic fluid of C. cellulosae was used as antigen in protein concentration of 2.5 micro-g/ml. Serum was diluted to 1:100 and CSF was undiluted in the assay for the specific IgG antibody level. The differential criterion of the positive reaction was the abs. of 0.18 in both samples. The results were summarized as follows: The overall sensitivity of the micro-ELISA in 71 confirmed neurocysticercosis was 90.1%; the sensitivity by serum was 77.5% and that by CSF was 83.1%. CSF was a more sensitive and valuable material. Most of the false negative cases of neuro-cysticercosis showed far lower level of abs. rather than marginal. The overall specificity of the micro-ELISA in 52 confirmed other neurologic diseases was 88.5%; the specificities by serum and by CSF were 94.2% respectively. Cases of other neurologic diseases did not show false positive reactions in both samples. When serum was assayed, taeniasis(2/18), sparganosis(2/20), paragonimiasis(1/56), clonorchiasis(1/15) and fascioliasis(1/1) cases showed cross reactions. When CSF was assayed, 2 of 10 neuro-sparganosis showed cross reactions while none of 9 neuro-paragonimiasis showed it. Out of 71 confirmed neuro-cysticercosis cases, 6 and 11 showed cross reactions by serum and CSF to crude extract antigen of sparganum; but no case did show it to crude extract antigen of Paragonimus westermani. Ventricular CSF showed low or negative levels of IgG antibody than lumbar CSF unless the lesion was at the lateral ventricle itself. Out of 4 racemose cysticercosis cases, 3 showed positive reaction in serum while all of 3 examined CSF were positive. The above results indicated that the serological test for detecting the specific IgG antibody by micro-ELISA using paired samples of serum and CSF was very helpful for clinical differentiation of neuro-cysticercosis from neurologic diseases of other causes.

An acephalic budding Cysticercus (= Racemose cysticercus) found at the abdominal wall of a man.

An acephalic budding Cysticercus of 1.2 cm long was removed surgically at the abdominal wall of a Korean man. The worm revealed abnormal buds on the bladder wall and absence of suckers and hooklets in the scolex body. The buds were of two histologic types; branching bud covered with normal tegumentum and with subtegumental cells of normal density, and buds of proliferated subtegumental cells with lacunae formation. On the bases of the morphologic features, it was identified as a racemose cysticercus. This case confirms that its extracranial location is possible.

Serological Diagnosis Of Human Sparganosis By Means Of Micro-ELISA.

Seven cases of surgically proven sparganosis were serologically tested by means of micro ELISA for their specific IgG antibody levels. For that purpose, crude saline extract of spargana from snake, Natrix tigrina lateralis was prepared and used as antigen. The sparganosis sera were also tested with Paragonimus and Cysticercus antigens to observe the cross reactivity. A total of 71 sera from normal control, ectopic and pulmonary paragonimiasis, clonorchiasis, cysticercosis and Taenia saginata cases were also included. Except for one case of old calcified infection, all of 6 human sparganosis showed higher serum levels of specific IgG antibody when the differential point of positive reaction was set at the absorbance value of 0.25 (the sensitivity being 85.7%). In control and other helminthic infections, all except 3 cases of T. saginata infection showed negative reaction to sparganum antigen (the specificity being 95.7%). None of sparganosis cases showed cross reactivity to Paragonimus and Cysticercus antigens. Undiluted cerebrospinal fluid also showed high levels of antibody when central nervous system was invaded. The serologic diagnosis by means of micro-ELISA could be a useful tool in epidemiological study of human sparganosis in susceptible population, as well as in individual diagnosis.

[The Status Of Intestinal Protozoan Infections In Inhabitants Of Gangweon-Do, Korea]

To evaluate the status of intestinal protozoan infections in inhabitants of Gangweon-Do, Korea, a total of 1,310 stool specimens (male 669, female 641) was collected from 2 cities and 3 counties. They were examined routinely 1 time by the method of formalin-ether sedimentation technique. The results were as follows: 1. The positive rate for any kind of the intestinal protozoan cysts was 8.9 %. 2. A total of 6 kinds of the intestinal protozoan cysts were detected. The prevalence rate of each protozoa were; E. histolytica 0.8 %, E. coli 7.6 %, E. nana 1.4 %, I. butschlii 0.2 %, G. lamblia 0.5 % and C. mesnili 0.5 %. 3. Sogcho-city showed the highest positive rate as 15.2 %, Myeongju county was the next as 11.3 % and Weonju-city showed the lowest positive rate as low as 3.9 %. 4. By age, the highest positive rate was found in 20-29 age group(12.4 %). Female (9.5 %) showed a slight higher positive rate than male (8.4 %).