Table of Content

28 February 1983, Volume 1 Issue 1

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CURRENT STATUS OF PREVALENCE AND CONTROL OF FILARIASIS IN THE PEOPLE'S REPUBLIC OF CHINA

1983, 1(1):  5-10. 

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Human filariasis in China prevails in 864 counties and cities covering 14 provinces, municipalities and autonomous regions (Taiwan Province not included), among which 467 (54.1%) were endemic to filariasis bancrofti, 225 (26.0%) to filariasis malayi, 138 (16.0%) to both types and 34 (3.9%) unidentified.The endemicity of filariasis in these counties and cities could be stratified into several strata based on the positive microfilariae rates before control: 419 counties and cities (48.5%) having infection rate below 5%, 318(36.8%) having 5.1-20.0%, 56(6.5%) having 20.1-30.0%, 11 (1.3%) over 30%, and 60 (6.9%) were unknown.It was estimated that prior to control there were about 30,994,000 filariasis patients, among them 21,962,000 suffered from filariasis bancrofti.The National Filariasis Control Program was initiated in 1956. The three therapeutic measures with DEC were: 1. selective treatment (microfilaraemia cases), 2. selective treatment and mass administration (all inhabitants above 5 years of age), 3. selective treatment and medicated table salt (9 grams of DEC within 6 months in areas endemic to bancroftian filariasis).In 1980, 21,313,000 filariasis patients (microfilaraemia positive and symptomatic) were found negatively conversed or cured. The filarial infection rate was likewise greatly reduced. Among the 864 endemic counties and cities the infection rate of 708 (81.9%) were below 5%, and filariasis in 265(30.7%) were virtually eradicated (The positive rate of microfilaraemia in a production brigade taken as the unit of count was reduced to below 1%).The fact that there are still about 9,681,000 filariasis cases to be treated calls for continuous and even greater effort on our part to put the disease under control in our country.

EXTRACTION, FRACTIONATION, AND CHEMICAL AND IMMUNOLOQICAL PROPERTIES OF UREA SOLUBLE SCHISTOSOMA JAPONICUM EGG ANTIGENS

1983, 1(1):  11-16. 

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Schistosoma japonicum eggs were homogenized in phosphate buffered saline (PBS). The precipitate was extracted with 8 M urea. The chemical and immunological properties of the urea soluble antigens (JEU) were compared with those of the aqueous soluble antigens (JSEA) .The total antigenic activity units of JEU were 2.83 times those of JSEA in kinetic dependent enzyme linked immunosorbent assay (K-ELISA). By Bio-Gel A 50 m chromatography, a fraction JEG3 was obtained from JEU. JEG3 was stable and of high antigenic activity. As a diagnostic antigen in detection of antibody in patient sera by K-ELISA, JEG3 was more sensitive than JSEA. Analysis of JSEA and JEG3 by sodium dodecylsulfate/polyacrylamide gel electrophoresis (SDS-PAGE), enzyme linked immuno-electro-transfer blot (ELIB) of SDS-PAGE, electrofocusing electrophoresis and high performance liquid chromatography (HPLC) showed that JSEA and JEG3 contained different antigenic components. The molecular weight of JSEA components was less than 200,000 daltons. The molecular weight of the main components of JEGS was greater than 400,000 daltons.This study is one of the ptojects of the US-PRC cooperation in Science and Technolgy of Medicine and Public Health. This joint work is carried out by The Institute of Parasitic Diseases, Chinese Academy of Medical Sciences and The Centers for Disease Control, USA

STUDIES ON THE ANTIGENS COMMON TO ADULT WORM AND CERCARIA OF SCHISTOSOMA JAPONICUM

1983, 1(1):  17-22. 

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Outbred Kunming mice infected with cercariae of Schistosoma japonicum were killed at definite intervals after infection. The serum of each mouse was assayed by indirect immunofluorescent antibody test for IgG against the surface antigen of cercaria. The worms in the same mouse were collected and examined for their stages of development. It was found that sera from mice with bisexual infections showed earlier appearance of IgG against cercaria and higher level as well than those from mice with unisexual male infections. Mouse anti-cercaria IgG could be absorbed with macerated adult worms or supernatants from adult worm cultures, but not with immature eggs nor cultures of mature eggs. Anti-cercaria IgG collected from infected mice showed strong immunofluorescence on the surface of both male and female adult worms, but not on the digestive tract not uterus. The intensity of fluorescence on the surface of adult worms by anti-cercaria sera diminished significantly after the sera had been repeatedly absorbed with cercariae. It indicates that the body wall of adult S.. japonicum and its turnover products can elicit the mouse antibodies against antigen (s) on the surface of cercaria, and that there are antigens common to adult worm and cercaria of S. japonicum.

SCANNING ELECTRON MICROSCOPY OF THE TEGUMENTAL SURFACE OF THE MAINLAND STRAIN OF SCHISTOSOMA JAPONICUM

1983, 1(1):  23-26. 

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The tegumental surface of the mainland strain of adult Schistosoma japonicum prepared by the CO2 critical point drying method was studied using scanning electron microscopy, in the depth of the oral sucker numerous silk-like villi were observed. At least three types of spines could be seen on the inner surface of both oral and ventral suckers. There were four types of bosses present on the tegument surface in the form of papilles, discoids, hillocks and balls with the former two types predominating. Papilla-like bosses are mainly distributed on the inner and outer edges of oral and ventral suckers, neck region and dorsal as well as ventral surfaces, while discoid-like bosses could be detected mainly on dorsal and ventral surfaces, neck region and inner surface of gynecophoric canal of male worms. They were probably sensory organelles according to some authors. Spines covering the inner surface of gynecophoric canal are sharp and knife-like but obtuse at their bases. Spines could also be found in neck region of the worms, but much less in male worms than in females. Numerous pores could be seen on the tegumental surface of the worms. It is worth noting that difference in fine details of the tegumental ultrastructure of adult Schistosoma japonicum from different reports may be of technical reasons. The technique hereby reported seems to be more suitable for scanning electron microscopy so as to avoid distortion in preparing living specimens.

SURVEY ON THE EFFECT OF CONTROL OF SCHISTOSOMIASIS IN 99 PRODUCTION BRIGADES OF 10 COUNTIES IN JIANGSU PROVINCE

1983, 1(1):  27-31. 

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A comprehensive survey on schistosome infection of the inhabitants and Oncomelania snails was made to evaluate the effect of the schistosomiasis control in 99 production brigades of 10 counties in Jiangsu Province.. Results showed that there existed significant changes. The positive rate of stool examination was reduced from 17.959% in 1970 to 1.09% in 1980. There was no new infection of the children aged below 10 in 92 % of the examined brigades. The reduction rate of the snail infested area was 98.83%. Among the 99 brigades, Oncomelania snails could not be detected in 55. Schistosome infected snails could be found only in 2 brigades. The mean snail density was reduced to 0.005/ square Chinese foot.However, there are still some problems. The remained patients, although few in number, are late and complicated cases mostly. The remained snail infested places possess the nature of "small, scattering and difficult to detect". Further effort is needed to eradicate schistosomiasis.This paper also considered that the new infection of children below 10 years of age may provide a sensitive index of the level of transmission and may be used as an important epidemiological measurement in the survey of anti-schistosomiasis effect.

COMPARATIVE STUDY ON DIFFERENT DOSE SCHEDULES OF PRAZIQUANTEL IN THE TREATMENT OF SCHISTOSOMIASIS JAPONICA

1983, 1(1):  32-36. 

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To further investigate the suitable dose-schedule of praziquantel for mass treatment of schistosomiasls, a comparative clinical study was carried out. 706 latent schistosomiasis cases were divided randomly into 3 groups: 1) 238 cases, each treated with a total dose of 50mg/kg in 1 day; 2) 244 cases, each with a total dose of 60mg/kg in 2 days; 3) 224 cases, each with a total dose of 72mg/kg in 3 days. The daily dose was divided into 3 portions given orally. A placebo containing yeast was given to 336 patients on the day or days when praziquantel was not administered to assess objectively the side-effects of the drug.All the patients except two tolerated praziquantel well and the course completed as scheduled. The main side-effects were dizziness, headache and fatigue. No significant differences were found among the 3 groups. However, higher percentage of side-effects were noticed in patients on the days receiving praziquantel than on the days receiving yeast. After treatment, except for 2 patients with premature beats, no remarkable changes were observed in liver or renal function tests, blood, urine, EEG or electromyogram on routine examination. Six months after praziquantel treatment, the stool examinations for miracidia in groups 1,2, and 3 were 100% (131/131), 96.9% (126/130) and 99.2% (127/128) negative respectively.The result suggests that the cure rates and side-effects were similar for the 3 groups. Praziquantel with a total dose of 50mg/kg in a day might thus be preferable for the mass treatment of schistosomiasis.

CLINICAL OBSERVATIONS ON THE EFFECT OF PYQUITON ON HEPATIC FUNCTIONS

1983, 1(1):  37-39. 

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This paper comments on the severity of side effects of pyquiton on the liver functions of the patients. The paper analysed the results of 664 cases of schistosomiasis japonica of various types, all treated by pyquiton during 1978-1981 and concluded that the liver damage produced by pyquiton in ordinary dosage was rare and mild. Cases with impaired liver function after the treatment of pyquiton were observed in only 2.29% of those with normal liver functions before treatment. 81.4 % of those with abnormal function before treatment or complicated with other liver diseases tolerated pyquiton well, while in -4.3% there were some aggravations of abnormal liver functions; but the damage was recovered rapidly under accessory hepatic treatment.The authors' data suggest that pyquiton is superior to other classical schistosomicides in causing little hepatic damage, so it can be used in schistosomiasis cases complicated with liver diseases.

A PRELIMINARY REPORT ON THE KINETICS OF CIRCULATING IMMUNE COMPLEXES IN SERA FROM RABBITS INFECTED WITH UNISEXUAL AND BISEXUAL CERCARIAE OF SCHISTOSOMA JAPONICUM USING POLYETHYLENE QLYCOL (PEG) PRECIPITATION

1983, 1(1):  40-43. 

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PEG with an average molecular weight of 6000 and a final concentration of 3.5% was used for the precipitation of circulating immune complexes in sera from infected rabbits. .The optical density (or the absorbance value) of the PEG precipitate of tested sera was determined with a 751 type spectrophotometer. The kinetic levels of circulating immune complexes (CIC) in sera from 51 rabbits infected with 10-50 bisexual and 5 rabbits with 25-50 unisexual cercariae of Schistosoma japonicum were observed respectively with PEG precipitation 2 to 14 weeks after inoculation. The absorbance values of PEG precipitates determined in sera from healthy rabbits were used as controls. The results have shown that the average absorbance values of CIC in sera from infected rabbits are markedly higher than those of PEG precipitates in sera from non-infected rabbits, the former increasing with the course and the intensity of infection. The levels of CIC in sera from rabbits infected with unisexual cercariae of Schistosoma japonicum were lower than those in sera from rabbits infected with bisexual cercariae. Both peaks of CIC appeared in the 12th week after infection and decreased steadily thereafter. It is suggested that the detection of CIC levels using PEG precipitation might be useful to indicate the state of infection in schistosomiasis japonica.

PREPARATION OF THE FREEZE-DRIED MEDIUM AND MICROPLATE FOR THE ASSESSMENT OF SENSITIVITY OF PLASMODIUM FALCIPARUM TO CHLOROQUINE IN IN VITRO MICROTECHNIQUE

1983, 1(1):  44-48. 

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In order to determine the extent and degree of chloroquine resistance of falciparum malaria in our country, we have prepared both the drug-coated microplates and freeze-dried medium for the in vitro microtechnique. Each microplate has 40 wells, four horizontal rows with 10 wells each, wells 1 and 10 were untreated to serve as controls and wells 2-9 coated with 1.0, 2.0, 4.0, 5.7, 8.0, 16.0, 32.0 and 64.0 pmol of chloroquine diphosphate. The freeze-dried medium contained RPMI 1640, HEPES buffer and 15% type AB human serum. Prior to use, it was stored under refrigeration. 0.9ml of 0.21% sodium bicarbonate solution was injected into a vial with freeze-dried medium and the latter dissolved by shaking, and then 0.1ml of patient's blood added, from which an aliquot of 50μl of the mixture being placed in each well. P. falciparum kept in continuous culture for more than a year was used for laboratory assessment of reliability of the freeze-dried medium and microplates. The results obtained showed that the freeze-dried medium stored for one year at 4℃ could still support the growth of malaria parasites while those at 36℃ for 5 days and at 26℃ for 10 days failed. Field investigation was carried out in some parts of Hainan Island, South Yunnan, west Guangxi, South Guizhou and East Anhui. The results showed that the home-made plates were equally effective as those provided by WHO. The application of the freeze-dried medium in the assessment of drug-resistant, malaria furnished the test with a good readability and proved to be suitable for field use. It is clear that the home-made freeze-dried medium might be an important tool in the surveillance of chloroquine resistant malaria.(This investigation received the financial support of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, SWG on the Chemotherapy of Malaria, Project ID No:800214)

STUDIES ON ANTIGENS OF THE HOUSE DUST MITE I.COLUMN CHROMATOQRAPHY AND IMMUNOLOGICAL DETERMINATIONS OF DERMATOPHAGOIDES FARINAE EXTRACT

1983, 1(1):  49-52. 

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The antigenic fractionations and activities of Dermatophagoides farinae were determined by biochemical and immunological methods. It was found that the optical densities (OD) of the fractions had 2 peaks (Sephadex G-50) or 3 peaks (Sephadex G-200), when D. farinae extract passed through gel filtration. The immunologic activities of the fractions were measured and the results did not parallel with the quantities of proteins (values of OD). The prick test to the inhalant asthmatics showed that allergens located between the first and second peaks. Counterimmunoelectrophoresis (CIE) showed that positions of precipitating antigens were within the range of the first peak. There were more proteins but only a few antigenic fractions in the second peak. No antigenic fraction was found in the third peak.

OBSERVATIONS ON THE DEVELOPMENT OF PARAGONIMUS WESTERMANI IN RATS AND ITS TREATMENT WITH PYQUITON

1983, 1(1):  53-56. 

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The results of the present experiment concerning the development of Paragonimus westermani in rats and its treatment with pyquiton were as follows.1. A wandering, non-encysted adult worm and many eggs of P. westermani were recovered in the liver of a rat (No. 6) 200 days after the infection with 100 encysted metacercaria. Two adults were found in the thoracic cavity of a rat (No. 8) 230 days after the infection also with 100 cysts. However, about 99% of the young worms (adolescents) were recovered in the muscles and the remainder 1% in the other parts (liver, thoracic cavity, etc.).2. Most of the young worms were killed in six infected rats treated with pyquiton in dosage of 120mg/kg body weight/day for two days. It is suggested that pyquiton is effective in treating rats infected with the adolescents of P. westermani.