Liver procollagen prolyl hydroxylase in Opisthorchis viverrini infected hamsters after praziquantel administration.

Infection of hamsters by the human liver fluke Opisthorchis viverrini elevated liver procollagen prolyl hydroxylase activity, reflecting increased collagen biosynthesis. The increase was proportional to the intensity of infection. However, the infected liver procollagen prolyl hydroxylase activity decreased after administration of praziquantel 300 mg kg-1 body weight, and approached normal levels two weeks after treatment. In the infected hamsters, praziquantel, at a curative dose, caused a transient increase in serum aminotransferase levels and a small but persistent rise in serum alkaline phosphatase. The drug, however, did not cause changes in these enzyme activities in the uninfected hamsters.

Opisthorchis viverrini: changes of the tegumental surface in newly excysted juvenile, first-week and adult flukes.

The tegumental surface of the newly excysted juvenile, first-week and adult stages of a human liver fluke, Opisthorchis viverrini, was studied by scanning electron microscopy. The surface of the newly excysted juvenile is characterized by circumferentially arranged ridges alternated with troughs which bear rows of spines encircling the body. These spines are characterized by the shapes of their edges: the first type with serrated edge appears on the anterior part, and the second type with single sharp edge appears on the middle part. There are no spines on the posterior part of the body. Three types of presumed sensory papillae are present: type A is a single small cone-shaped ciliated papilla; type B is a group of ciliated papillae on a common dome-shaped base; and type C is a large papilla with nonciliated bulb. Type A papillae are scattered evenly on the surface but are more concentrated around the oral and ventral suckers, as well as the excretory pore. Pairs of both type A and B papillae are located in rows along the lateral surfaces of the body. Type C papillae are located solely on the lip of the ventral sucker. In the first-week fluke the tegumental surface appears corrugated and covered with short developing microvilli, and spines are mostly lost. In the fully-grown adult fluke the surface appears highly corrugated with wave-like folds encircling the body which are covered in turn with closely packed stubby microvilli. Microvilli are more numerous and are taller on the ventral than on the dorsal surface. Among microvilli on the surface of both older stages three types of sensory papillae as in the newly excysted juvenile were observed, but they are of larger sizes. The number of type A papilla increases whereas that of type B papilla decreases during maturation. The distribution of papillae in both stages is similar to the newly excysted stage.

Opisthorchis viverrini: ultrastructure of the tegument of the first-week juveniles and adult flukes.

The tegument of one-week-old and adult flukes of Opisthorchis viverrini were studied by transmission electron microscopy. The tegument of both stages is composed of a syncytium formed by processes of the tegumental cells lying underneath the outer-circular and the inner-longitudinal muscle layers. The tegument is bounded by trilaminate outer and inner membranes; the former is coated with a thin glycocalyx, while the latter has short basal infoldings. There are 4 forms of tegumental granules, namely dense spherical, dense discoid, light spherical and light discoid granules. Dense spherical and dense discoid granules have similar dense homogeneous and highly electron-dense matrices; thus, they may represent different planes of sections of biconcave granules, and may contribute their content to the formation of the outer membrane and the glycocalyx. Light spherical and light discoid granules may be another type of granule whose filamentous content may contribute to the formation of the microtrabecular network in the tegument. Microvilli start to develop in one-week-old juveniles and become fully developed in adult stages. The size, number and cristae of the mitochondria become increasingly more numerous along with the development of microvilli; in the first-week juveniles most mitochondria are located in the basal portion of the tegument while in adults most lie within microvilli underneath the outer membrane. The tegumental cell is irregular in shape and contains a nucleus with a prominent nucleus, abundant rough endoplasmic reticulum, well developed Golgi complexes, ribosomes, mitochondria and numerous tegumental granules.(ABSTRACT TRUNCATED AT 250 WORDS)

Predisposition to reinfection by intestinal helminths after chemotherapy in south Thailand.

Rates of reinfection by the intestinal helminths hookworm, Ascaris lumbricoides and Trichuris trichiura after chemotherapy were studied in two villages in Phang-Nga Province, southern Thailand. It was found that intensity of infection levels attained after reinfection correlated positively with pretreatment intensities of infection for all parasites. This implies that certain persons in the community are predisposed to receiving high numbers of worms, due either to environmental or personal risk factors. Therefore, it would be advantageous to identify such persons and treat them preferentially. Targeted chemotherapy, however, should be combined with efforts to identify the risk factors that vary within the community and direct educational efforts or environmental intervention towards the section of the community most affected by the parasites.

Prevalence, incidence, intensity and associated morbidity of intestinal helminths in south Thailand.

Intensive surveys for Ascaris lumbricoides, Trichuris trichiura and hookworm were carried out in two villages in Phang Nga Province, southern Thailand, in order to measure prevalence, estimate incidence and determine the relation between intensity of infection and morbidity before and after chemotherapy. The study populations were a small upland village community (Nai Tone) and a grade school in a small coastal village (Boh Saen). About half of the Nai Tone villagers were given a broad spectrum antihelminthic (albendazole), and the Boh Saen students were all treated successively with three drugs: piperazine citrate to treat for Ascaris, pyrantel pamoate to treat for hookworm, and mebendazole to treat for Trichuris. Stool examinations were made using the quick Kato smear technique, questionnaires were administered concerning a variety of possible symptoms, and anthropometric and blood biochemical parameters were measured both before and after treatment. The prevalence of Ascaris was 31.0 and 22.6%, hookworm was 89.1 and 88.0% and Trichuris was 59.7 and 77.8% in the Nai Tone and Boh Saen study populations, respectively. Average intensity of Ascaris was highest in the 0-9 year age class (greater than 32,000 epg) in Nai Tone Village. Hookworm intensity of infection was higher in males than in females in all age classes, and in Nai Tone Village at least 25% of males and 20% of females had 8000 or more epg of faeces. Trichuris intensity of infection was highest between 5 and 10 years of age in both populations. The only signs or symptoms showing a significant (P less than 0.05) difference between high and low classes of intensity of infection and a significant improvement (P less than 0.01) after drug treatment, were headache and flatulance in the case of hookworm infection in Boh Saen School. The presence of multiple infections made testing of hypotheses concerning particular parasite species difficult.

Chromosomal differentiation of the Schistosoma japonicum complex.

The C-banding pattern, location of telomere sequence and chiasma frequency of four species of the Schistosoma japonicum complex were compared with those of two African species, Schistosoma mansoni and Schistosoma haematobium. In the six species, C-banding patterns of seven autosomes and the two sex chromosomes (Z and W) showed relatively species-specific and geographical (Asian and African) differences. Particularly, a plausible pathway of alteration of chromosome 2 revealed a direction from the A-chromosome to the M- chromosome in terms of rearrangements of pericentric inversion and elimination of constitutive heterochromatin (AM inversion). This chromosome change suggested hypothetically that the S. japonicum complex is the original type, and the African species represents the derived type. Moreover, the mosaic construct of the Asian and African types in Schistosoma sinensium chromosomes prompted us to propose that the species might have been formed by hybrid speciation of the genomes of Asian and African species. Localisation of telomeric repeats enabled Asian and African schistosomes to be distinguished clearly by simple terminal location and by terminal and interstitial locations, respectively. Change of chiasma frequency in the S. japonicum complex might be caused by the reduction of interstitial chiasmate (Xi) in the larger chromosomes, 1 and Z (or W), and the change seems to have progressed to Japan from South East Asia. These data enabled us to predict a tentative evolutionary pathway of schistosomes at the cytogenetic level.

Control of Schistosoma mansoni transmission by chemotherapy in St. Lucia. II. Biological results.

Chemotherapy of all persons infected with Schistosoma mansoni was begun in Marquis Valley, St. Lucia, in March 1974. From January 1972 to the start of chemotherapy, the infection rate in field Biomphalaria glabrata collected in the valley was 1.09% (117/10,736) and the rate in sentinel B. glabrata was 1.48% (56/3,790). From March 1974 through December 1975, no infections were detected in either field snails (11,742 collected) or sentinel snails (3,230 exposed). The accumulated date suggest that, because of differences in topography and average annual rainfall, S. mansoni transmission occurs in this valley during the rainy season, whereas in other St. Lucian valleys under study it occurs during the dry season.

Genetic variation and differentiation of three Schistosoma species from the Philippines, Laos, and Peninsular Malaysia.

Electrophoretically-detected allozyme variation is described in strains of Schistosoma japonicum (4 Philippine strains), S. mekongi (Laos), and an undescribed anthropophilic S. japonicum-like schistosome from Peninsular Malaysia. Result, together with those reported previously for 8 other strains (S. japonicum, China, Formosa, Japan, Philippines; S. mekongi, 2 substrains; Malaysian schistosome, 2 strains) permit a composite genetic characterization of 15 strains of Asian schistosomes at 9-18 presumptive loci. The proportion of polymorphic loci (P) and the mean heterozygosity per locus (H) were zero in all strains. Although this was expected for strains that had been in laboratory culture for up to 50 years, we expected to detect variation in strains based on 10-50 recently field-collected infected snails. We expected S. japonicum to be as variable as S. mansoni (P = 0.13 (0-0.33), H = 0.04, 18 loci, 22 strains) as it is believed to reproduce sexually, has an evolutionary history of several million years, inhabits a wide geographic range, coevolved with a genetically variable intermediate snail host, and has a diversity of mammalian hosts. No differences were detected between the 5 S. japonicum strains from Leyte and Luzon (Philippines), between the 3 S. mekongi strains, or between the 3 Malaysian schistosome strains; these groups and the remaining S. japonicum strains representing Mindoro (Philippines), China, Formosa, and Japan each have distinctive multilocus electromorphic patterns. Nei's genetic distances (D) were calculated to estimate interstrain and interspecific divergence. Interstrain genetic distances in S. japonicum averaged greater than 0.3; much higher than those reported previously for S. mansoni (D = 0.06, D(max) = 0.24). S. japonicum (Mindoro) was moderately differentiated from the Leyte-Luzon strains (D = 0.29, 12 loci). Estimates of the S. japonicum China-Philippine distance (D greater than 0.4, 11 loci) are high for conspecific populations and further studies of the still poorly characterized Chinese parasite may reveal that these are, in fact, separate species. S. japonicum is shown to be only distantly related to S. mekongi and the Malaysian schistosome (D greater than 1); the latter is closely related to, but genetically quite distinct from, S. mekongi (D = 0.61 +/- 0.275, 11 loci) and warrants recognition as a new species. The medical significance of the isogenic nature of the Asian schistosome strains and their evolutionary divergence are discussed.

Laboratory and field trials of a slow-release copper molluscicide in St. Lucia.

Tests of a slow-release molluscicide containing 50% copper sulfate were under-taken in laboratory and field situations in St. Lucia. In laboratory trials, a granule form of the molluscicide produced 100% mortality of Biomphalaria glabrata down to 4 mg/liter active ingredient (a.i), while the pellet form produced 100% mortality down to 8 mg/liter a.i. In field trials, a dose of 100 mg/liter a.i. in granule form caused mortality of B. glabrata in banana drains but had no effect on B. glabrata populations in a marsh habitat. In both habitats, the dose of 100 mg/liter produced mortality of other molluscan fauna which caused changes in the molluscan diversity indices. This failure in field trials may have been due to dilution of copper levels caused by flooding and also by uptake of copper by mud and algae.

Incidence of endemic Opisthorchis viverrini infection in a village in northeast Thailand.

Incidence, measured as the proportion of persons whose stools become positive within one year, was studied in endemic Opisthorchis viverrini, the human liver fluke, in a northeastern Thai village over a two-year period. Incidence was higher in males than in females, especially in children under five years of age. It was at least 47% overall in the first year of the study, but declined to below 20% per year in the second. This is attributed to drying of a local water reservoir and decline in availability of infective stages in fish. The fluctuation of incidence is probably due to the large variations in rainfall from year to year. The rate of reversion from positive to negative varied from 2% to 6% per year.

Consistency of fecal egg output in patients with Opisthochiasis viverrini.

Counts of Opisthorchis eggs in two samples of feces arbitrarily taken 0-21 days apart from each of 209 patients from northeastern Thailand were carried out by Stoll's dilution technique. Based on the number of eggs/mg feces, each patient was classified as uninfected, lightly infected (less than 1 egg/mg), moderately infected (1-10/mg), heavily infected (greater than 10-50/mg), or very heavily infected (greater than 50/mg). The intensity of infection for each of the 209 individuals as shown by first and second counts was compared. Of the 209 individuals, 150 (71.8%) remained within the same egg excretion category, with all but five (2.4%) of the remainder being in an adjacent category. Statistical analysis showed no effect of variation in interval between stool counts on the accuracy or consistency of replicate counts.

Morbidity in relation to intensity of infection in Opisthorchiasis viverrini: study of a community in Khon Kaen, Thailand.

A study of the prevalence and intensity of opisthorchiasis viverrini in relation to morbidity as determined by standard medical examination was carried out in Nong Ranya, a small village containing 309 people in northeastern Thailand. Opisthorchis viverrini infection as determined by Stoll's quantitative egg count method had an overall prevalence of 94% and reached 100% prevalence in most age groups above the age of 10 years. With respect to intensity, 6% were uninfected, 26% had light (less than or equal to 1 eggs per mg [epmg] of feces), 37% moderate (greater than 1-10 epmg), 25% heavy (greater than 10-50 epmg), and 5% very heavy (greater than 50 epmg) infections. Peak intensity in both males and females occurred at age 40 and above. A history of eating "koipla" (a sauce consisting of ground up raw fish), of feeling weak, and of having right upper quadrant abdominal pains occurred most frequently in the infected groups and was correlated with intensity of infection. Regardless of intensity of infection, only a small proportion of the population were unable to carry out their routine activities. Anorexia, nausea or vomiting bore little relationship to the presence or intensity of infection. Hepatomegaly at the mid-clavicular line occurred in 14% of the population, mainly in the more heavily infected groups. Neither jaundice nor splenomegaly was observed in the population.

Opisthorchis viverrini infection in rural and urban communities in northeast Thailand.

The prevalence and intensity of liver-fluke (Opisthorchis viverrini) infection were investigated among 559 patients who were born in, and had lived all their lives in, either the rural or urban northeastern Thailand. 344 (79.4%) of 433 rural dwellers were infected compared with only 69 (54.8%) of 126 urban dwellers (P less than 0.005). The intensity of infection, and the reported level of consumption of koi-pla, a favourite dish of local inhabitants prepared from uncooked freshwater fish which often contains viable metacercariae, were greater among rural dwellers than their urban counterparts (P less than 0.05 to P less than 0.005). Infection due to O. viverrini appears to be mainly a rural problem strongly associated with the habit and frequency of eating koi-pla.

Measurement of incidence of the human liver fluke, Opisthorchis viverrini, in northeast Thailand.

A survey of a community in northeast Thailand where Opisthorchis viverrini is endemic permitted comparison of two methods of measuring incidence: direct determination of the rate at which an uninfected group became infected between two surveys a year apart, and estimation of incidence from age-specific prevalence data using a logarithmic regression method. Both methods revealed that incidence increased with age in young children, and estimation from age-prevalence data showed that the increase was roughly linear from near birth to about age 5 years, beyond which no clear trend in incidence was evident. A catalytic infection model incorporating an infection rate increasing from birth to age 5, and remaining constant thereafter, gave an excellent fit to age-prevalence profiles. Both methods of determining incidence are sensitive to errors in diagnosis, but the direct determination method is more sensitive to the presence of false negatives. A method for correcting this bias is given. The regression method, which was less sensitive to yearly variation in incidence and is easier to use, is recommended for preliminary surveys to identify villages with high transmission intensity.

Opisthorchis viverrini and opisthorchiasis: a historical review and future perspective.

Opisthorchiasis is caused by the liver fluke, Opisthorchis viverrini. The fluke afflicts approximately seven million inhabitants in northeastern and northern Thailand. The fluke utilizes, respectively, freshwater snails and cyprinoid fish as its first and second intermediate hosts. Man is the accidental definitive host who acquires infection through the consumption of improperly cooked fish. Information pertaining to the history, the life-cycle, the epidemiology and transmission dynamics, and diagnosis of the fluke is compiled and presented.

Relationship between female Anopheles dirus (Diptera: Culicidae) body size and parity in a biting population.

Wing length of host-seeking Anopheles dirus Peyton & Harrison was measured in Tha-Mai District, Chanthaburi Province, Thailand. Overall, wing length of nulliparous females (mean = 3.035 mm) was not significantly smaller than that of parous females (mean = 3.039 mm). Wing length was correlated with rainfall and minimum air temperature; females tended to be smaller in the rainy season and larger in the cool and early dry seasons, often in association with a high parity rate. Malaria transmission potential based on daily survivorship was estimated to be highest during the cool and early dry seasons, and during the first half of the rainy season.

Molecular cloning and characterization of cathepsin L encoding genes from Fasciola gigantica.

In this study cDNAs encoding cathepsin L-like proteins of Fasciola gigantica were cloned by the reverse transcription polymerase chain reaction method (RT-PCR) from total RNA of adult specimens. DNA sequence analyses revealed that six different cathepsin L cDNA fragments were isolated, which have DNA sequence identities of 87-99% towards the homologous genes from F. hepatica. Gene expression was studied at the RNA level by Northern and RNA in situ hybridizations. Northern analysis showed the cathepsin L genes to be strongly expressed in adult parasites as a group of 1050 nt sized RNAs. RNA in situ hybridization localized cathepsin L RNA to the cecal epithelial cells. Southern hybridization was used to determine the number of cathepsin L genes and indicated the presence of a family of closely related cathepsin L genes in the genome of F. gigantica.

Cadmium biosorption by cells of Spirulina platensis TISTR 8217 immobilized in alginate and silica gel.

The biosorption of cadmium by immobilized Spirulina platensis on alginate gel and silica gel was studied. The maximum biosorption capacities for alginate immobilized cells and silica immobilized cells were 70.92 and 36.63 mg Cd/g biomass, respectively. Temperature did not have an influence on metal sorption, whereas an initial pH solution did. Sorption occurred in a wide pH range (pH 3-8). The highest adsorption of alginate immobilized cells was at pH 6, while silica immobilized cell adsorption was not affected at pH between 4 and 7. The immobilized cells were reused in consecutive adsorption-desorption. The results showed that immobilized cells could be repeatedly used in the sorption process up to five times.

Production and characterization of a monoclonal antibody against recombinant fatty acid binding protein of Fasciola gigantica.

In Fasciola parasites fatty acid binding proteins (FABPs) are the carrier proteins that help in the uptake of fatty acids from the hosts' fluids. Attempts have been made to utilize both native and recombinant FABP (rFABP) for immunodiagnosis and vaccine development for fasciolosis. In this study, we have produced a number of monoclonal antibodies (MoAbs) against rFABP of Fasciola gigantica. These MoAbs were initially screened against rFABP by ELISA and then tested for their specificities by immunoblotting. Five stable clones were selected and characterized further: four of them were of the isotype IgG(1) while one clone was IgG(2a). All the MoAbs reacted with rFABP which has a molecular weight (MW) of 20 kD and with at least two isoforms of native proteins at MW 14.5 kD that were present in the tegumental antigen (TA) and crude worm extracts, and the excretion-secretion materials. Immunoperoxidase staining of frozen sections of adult parasites by using these MoAbs as primary antibodies indicated that FABP were present in high concentration in the parenchymal cells and reproductive tissues, in low concentration in the tegument and caecal epithelium. All MoAbs cross-reacted with a 14.5 kD antigen present in the whole body (WB) extract of Schistosoma mansoni, while no cross-reactivities were detected with antigens from Eurytrema pancreaticum and Paramphistomum spp.

Cadmium biosorption by Sphingomonas paucimobilis biomass.

Among microorganisms isolated in Bangkok, the gram-negative bacterium Sphingomonas paucimobilis exhibited the greatest cadmium tolerance. It was able to survive in the medium containing cadmium as high as 200 mg/l. However, concentrations of cadmium at 25-200 mg/l inhibited its growth. The biosorption properties for cadmium of this bacterial biomass and the effects of environmental factors (i.e., biosorbent type, initial pH and biosorbent concentration) on the cadmium biosorption were explored. The results showed that the cadmium removal capacity of living cells was markedly higher than that of nonliving cells. Cadmium biosorption by S. paucimobilis biomass was also affected by the initial pH and biosorbent concentration.