Table of Content

31 August 1987, Volume 5 Issue 3

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A PRELIMINARY STUDY ON THE INFECTIVITY OFDIFFERENT GEOGRAPHIC STRAINS OF PLASMODIUMVIVAX TO ANOPHELES SINENSIS

1987, 5(3):  161-164. 

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Anopheles sinensis from Shanghai and Guangxi were experimentally infected with Ha-inan and Guangxi strains of Plasmodium vivax. It was found that both anopheline mos-quitoes had a very low susceptibility to the Guangxi strain, the gland infection rate being 0 and 12.3% (43.2% for Are, minimus serving as control), while they showed distinctly higher susceptibility to the Hainan strain, the respective gland infection rate being 36.4% and 43.6% (100% for An. minimus).Two lots of An. sinensis from Wuhan were experimentally infected with Guangxi strain of P. vivax from two patients. It was shown that they had just the same low susceptibility as An. sinensis from Guangxi. The gland infection rate of the two lots of mosquitoes was 4.6% and 30.6% respectively, although it has already been confirmed that An. sinensis from Wuhan was highly susceptible to the indigenous strain of P vivax. From the present experimental results and literature, it is evident that there exist in China different geographic strains of P. vivax with varied infectivity to Are. sinensis.

ROLE OF RESPIRATION IN THE ENERGY METABOLISM OF SCHISTOSOMA JAPONICVM

1987, 5(3):  170-172. 

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The respiratory rates of adult male, female, as well as coupled schistosomes were determined. It was observed that the worms harvested from the liver and mesenteric veins of mouse after treating the experimental animals with fluoroacetamide (CF) did show a considerable reduction in respiration. Once the respiration was inhibited over 50%, hepatic shift of worms occurred. Using succinate as substrate, the effects of ADP, antimycin and oligomycin on the worm mitochondria was investigated, it was shown that ADP stimulated the respiration, whereas antimycin and oligomycin inhibited it.

STUDIES ON CONTROL MEASURES OF VIVAX MALARIA IN JUYE COUNTY, SHANDONG PROVINCE

1987, 5(3):  173-175. 

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Juye county is situated in southwest Shandong Province, belonging to the Huanghuai Plain covering an area of 1 230 km2. The total population is 660 thousand. Anopheles sinensis is the malaria vector and epidemic outbreaks of vivax malaria were easy to occur. In order to seek an effective antimalaria strategy, field trials of control measures have been conducted since 1971. Through 15 years' successive antimalaria work the annual incidence dropped from 211.5‰ before the campaign to 0.003‰ in 1985. The results demonstrated that the complex measures with particular emphasis on controlling the source of infection are practicable for malaria control in this area.

STUDIES ON DELTAMETHRIN IN THE CONTROL OF PERI-WILD PHLEBOTOMVS CHINENSIS

1987, 5(3):  176-179. 

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Residual spraying to control Phlebotomus chinensis with deltamethrin was applied to all field caves and 13-14 villages within the radius of 10 km2 surrounding Yunyan town in 1985-1986. The dosage used was 25 mg/m2 in field caves and livestock caves and 12.5 mg/m2 in villages. The test area covered 74000 m2. In 1985, after spraying, sandfly density decreased to very low level until the end of sandfly season. However, it was still very high in unsprayed field caves throughout the sandfly season.Three and a half months after spraying, sandfly specimens were collected and forced to contact the intact sprayed wall surface. The first knock-down time was between 33 to 61. minutes. However, contact with poorly sprayed wall surface gave a longer knock-down time between 75 and 305 minutes.In 1986, after spraying, the sandfly densities were markedly decreased as compared with the same months in the previous year. In June in the unsprayed area the sandfly density decreased by 79.1% in field caves and 71.5% in livestock caves of village. In August, the sandfly density decreased by 46.9% in the field caves and 59.6% in village area. The results showed that the residual potency effect of deltamethrin was long enough to suppress sandfly density throughout the sandfly season (3.5 to 4 months).Deltamethrin spraying (25 mg/m2) in field caves and livestock caves before or at the beginning of sandfly season, was effective and practical in the control of peri-wild P. chinensis in the loess plateau of northern Shaanxi.

EFFECTS OF CYCLOPHOSPHAMIDE ON THE DEVELOPMENT OF EXO-ERYTHROCYTIC FORMS OF PLASMODIVM YOELII IN RATS

1987, 5(3):  180-183. 

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The percentage of sporozoites developed in exoerythrocytic forms in the rats treated intravenously with cyclophosphamide 24 hrs before inoculation of sporozoites was higher than that in untreated controls, so was the mean size of exoerythrocytic form. Cyclophosp-hamide could decrease the sensitivity of hepatocytes to the vector's tissues inoculated together with sporozoites, thus decreasing the incidence of cloudy swelling of hepatocytes induced by the vector's tissues and inhibiting the white blood cells infiltration induced by the ruptured mature exoerythrocytic form.The fact that cyclophosphamide might enhance the invasion of sporozoites into the hepatocytes indicates that the phagocytic activity of Kupffer's cells to destroy the sporozoites might be inhibited by cyclophosphamide.

EFFECTIVENESS OF "HUNMIEWEI" AND DELTAMETHRIN RESIDUAL SPRAYING IN CONTROLLING ANOPHELES SINENSIS

1987, 5(3):  184-187. 

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The effectiveness of "hunmiewei" and deltamethrin against A. sinensis was evaluated by means of susceptibility test, experimental huts and field trial during 1983-1984 in Tangtou of Shinan. The results showed that both insecticides were highly toxic to A. sinensis which had developed high resistance to organochlorine and organophosphorus insecticides. The residual effect on bamboo walls in the experimental huts was three months or more for deltamethrin at 25mg/m2 and 45-50 days for "hunmiewei" at 2g/m2. In a field trial, house spraying of deltamethrin and "hunmiewep at the above mentioned dose, two rounds in a year, could reduce vector capacity of A. sinensis by 91.4% and 85.2% respectively as compared with that in control village; when insecticides were used in combination with adequate chemotherapy including anti-relapse treatment, case radical treatment and presumptive treatment in the sprayed areas, the morbidity rates of vivax malaria were decreased by 43.0% and 42.2% respectively as compared with those of last year.

DETECTION OF SERUM ANTIBODIES IN BANCROFTIANFILARIASIS PATIENTS WITH ANTIGENS FROM DIFFERENTDEVELOPMENTAL STAGES OF BRVGIA MALAYI

1987, 5(3):  188-190. 

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Sera of patients with bancroftian microfilaraemia were detected for antibodies using three different stage antigens of Brugia malayi, which were microfilaria treated with pa-pain (MTP), cryosection of infective larvae (CIL) and cryosection of adult worm (CAW) by indirect fluorescent antibody test.The experimental results showed that there were no statistical differences between MTP and CAW in sensitivity and specificity, the positive rate in patients with microfilaraemia being 95.3% and 93.7%, the false positive rate in pregnant women and infants in non-endemic area of filariasis being 3.9% and 0, and the cross-reaction rate in patients with cysticercosis being 12.5% and 25.0% respectively. The positive rate of CIL was 76.2%, the false positive rate was 11.5%, and cross-reaction rate was 18.8%.It is considered that the antigen of microfiiaria treated with papain might be more appropriate to be applied than the antigen of cryosection of adult worm in seroepidemio-logical investigation for bancroftian filariasis, due to the convenience and simplicity in the collection and preparation of antigen.

VECTORIAL CAPACITY OF ANOPHELES LESTERIANTHROPOPHAGVS IN TRANSMITTING FILARIASIS MALAYIIN LESHAN PREFECTURE, SICHUAN PROVINCE

1987, 5(3):  191-193. 

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The mosquito vector of filariasis malayi and its vectorial capacity was investigated In 5 endemic villages in Leshan Prefecture, Sichuan Province. The results showed that the man-biting rate, numan blood index and vectorial capacity of An. lesteri anthropophagus were 0.7, 5.1 and 10.63 times higher than those of An. sinensis. Besides, the natural infection by microfilaria in An, lesteri anthropophagus was also higher than that in An. sinensis by 5 times.From the above result, the authors concluded that An. lesteri anthropophagus was the main vector for transmitting filariasis malayi in the area under study.

COMBINED USE OF PYRONARIDINE, SULFADOXINE AND PRIMAQUINE IN AREAS WITH CHLOROQUINE-RESISTANT FALCIPARUM MALARIA

1987, 5(3):  194-196. 

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Fourty-eight falciparam malaria cases were treated by pyronaridine phosphate (1.2 S base) jointly with sulfadimoxine (1g) and primaquine phosphate (45 mg base) in 2 days in Mengla County, Yunnan Province, where chioroquine-resistant Plasmodium falciparum is endemic. 36 falciparum malaria cases were treated with pyronaridine (1.2 g) alone. The average defervescence time of the combined treatment group and the pyronaridine group was 32 ±16 h and 32.7±16h; the mean asexual parasite clearance time of the groups was 59±20.8 h and 64 ± 22.9 h respectively. During 1 month follow-up, the asexual parasite recrudescence irate of the 2 groups was 2.5% and 15.2%; the gametocyte-carrying rate was 50.0% (19/38) and 93.9% (31/33). No marked side effects were observed in the co-mbined therapy.

A SIMPLE PRELIMINARY SCREENING METHOD FOR ANTIMALARIAL DRUGS

1987, 5(3):  200-202. 

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Since many chemicals including biochemical inhibitors and natural materials are difficult to get in large amount, a more sensitive method for preliminary screening is needed.The authors found that an intraperitoneal injection of Na125I mixed with an emulsifier composed cf lanolin and liquid paraffin could keep higher concentration for 3-4 days in mice, while Na125I solution alone could only persist for one day. On this basis, the solution or fine suspension of drugs (e.g. chloroquine and pyrimethamine) in water was mixed with the emulsifier and injected once intraperitoneally into mice three hours after Plasmodium yoelii infection. Blood smears were taken on the fifth day, the number of infected RBC were counted and all the procedures were just the same as the four days oral administration method recommended by WHO for another group of infected mice.By comparing the two methods mentioned above, when one day's dosage of oral administration method was used for injection, very similar results were obtained. Thus, the new method seems to be more labour-saving and especially suitable for the screening of drugs which were limited in supply.

LONGEVITY AND PERIODICITY OF MICROFILARIAE OF BRVGIA MALAYI TRANSFUSED TO VARIOUS STRAINS OF LABORATORY MICE

1987, 5(3):  203-206. 

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Microfilariae (mff) obtained from the peritoneal cavities of infected jirds (Meriones unguiculatus) were injected intravenously into 6 mouse strains: SMMC/B, BALB/cCR, LACA, ICR/JCL, 615 and Kunming strain. The mff in the peripheral blood of the 6 mouse strains in the above sequence were detectable within 1-150, 24-80, 30-60, 3-96, 12-45 and 45-60 days after inoculation of 2 × 105 mff per mouse. The survival period of mff was longer in SMMC/B mice than in mice of the other strains, and the density of mff in blood was also higher in the former than in the latter. Out of 18 SMMC/B mice 13 remained microfilaria-positive on the 60th day after inoculation. The duration and level of microfilaraemia were proportional to the dose of parasites injected Microfilariae disappeared from the peripheral blood of all mice 3 days after injection of 1 ×104 mff, but were still detectable 60 days after injection of 2 × 105 mff. In addition, mff disappeared much faster from the peripheral blood of SMMC/B mice after the second inoculation than after the first one. Although the mff had already disappeared from the peripheral blood of the infected and reinfected mice for about 1 to 2 months, they could still be found in the internal organs, mostly in the small blood vessels of the lungs (about 90%). The mff maintained a nocturnal sub-periodicity in the recipient mice, similar to those observed in the donor jirds, with a peak density hour between 2:28 and 5: 48 a.m.The results show that this mouse model might be a simple and useful system in which various factors controlling the fate of mff can be studied independently.

EFFECTS OF PRAZIQUANTEL ON THE TEGUMENTOF DIFFERENT DEVELOPMENTAL STAGES OF SCH1STOSOMAJAPONICUM AND HOST CELL RESPONSE

1987, 5(3):  207-209. 

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Mice harbouring different developmental stages of Schistosoma japonicum were treated orally with praziquantel at a single dose of 400 mg/kg and sacrificed 0.5-24 h after the medication for histological observation.After praziquantel treatment, the tegument of dc(3 h), d28, d35, and d42 schistosomes showed extensive vacuolation and rupture, while in d3, d7, d11, d14 and d21 schistosomules, little or only a mild local vacuolation of the tegument was detected. Strong host celt response was seen around the damaged d0, d28, d35 and d42 schistosomes, and the cells found were largely polymorphonuclear leucocytes. However, around d3-21 schistosomules, the cells were mainly lymphocytes and the host cell response was rather weak.The results confirmed that Schistosoma japonicum exhibited stage-specific susceptibility to praziquantel.

STUDIES ON KARYOTYPE OF PARAGONIMVS WESTERMANI FROM YUEQING COUNTY, ZHEJIANG

1987, 5(3):  210-212. 

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The karyotype of Paragonimus westermani from Mayang Hill, Yueqing County of southern Zhejing Province, which is still an endemic area of paragonimiasis characterized by the finding of eggs of the parasite in sputum, was studied. The chromosome number is 2n = 22, and the karyotype consists of one pair of large-sized metaeentric, four pairs of medium-sized subtelocentrics, four pairs of small-sized submetacentrics and two pairs of small-sized metacentrics. In addition, spermatozoa were found in seminal receptacle in 97.8% of the adult worms, and the paragonimus metacercaria in Sinopotamon chekiangense was smaller, suggesting that this worm belongs to the bisexual type of P. westermami. Since tne worms under our observation were collected from the endemic area mentioned above, it was suggested that P. westermani with diploid pattern (or bisexual type) might cause typical pulmonary manifestations.

SEVEN YEARS' FOLLOW-UP OBSERVATION ON TREATMENT OF SCHISTOSOMIASIS WITH PYQUITON

1987, 5(3):  213-216. 

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A 7 years' follow-up observation on treatment of schistosomiasis with pyquiton was made in 1986. 339 cases were examined 1, 3, 6,12,30,48 and 84 months after treatment by stool hatching for miracidia and concentration method for eggs. The cumulative negative conversion rate was 99.2%. Detailed history was taken and physical examination was made in 224 out cf 339 cases. No sequelae were seen. Before treatment 93 cases (41.5%) had hepatomegaly below the costal margin, 166(69.6%) below the xyphoid process. 73 cases (32.6%) had splenomegaly. Follow-up examination 7 years post-treatment revealed hepatomegaly below the costal margin in 30 cases (14.4%), below the xyphoid process in 49 cases (21.9%) and splenomegaly in 18 cases(8%). Immunological tests performed 7 years post-treatment revealed a negative conversion rate of 91.7% (99/108) with ELISA and 85.2%(46/54) with COPT. The authors consider that pyquiton is the drug of choice for the treatment of schistosomiasis japonica.

SCANNING ELECTRON MICROSCOPY OF THE METACERCARIA OF PARAGONIMUS ILOKTSUENENS1S

1987, 5(3):  217-219. 

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The present report is concerned with the surface structure of the metacercaria of Pa-ragonimus iloktsuenensis as visualized with the scanning electron microscopy. The meta-cercariae were obtained from the liver of tne Sesarma dehaani collected in Yingkou county, Liaoning Province.The tegumental spines of the metacercaria are single-pointed and densely distributed over the entire body and are slightly different in size and shape in different parts of the body. On the forebody of the ventral surface, a vertical ridgeline can be seen in the middle of the spines.In addition to the short spines, there are two circles of non-ciliated papillae on both lips of the oral and the ventral suckers. Around the oral sucker, there are 12 papillae on the outer circle and 6 on the inner circle; around the ventral sucker, there are 6 papillae on both the outer and inner circles. No sensory papillae were found around the ventral sucker. On each side of the anterior part of the ventral side, 8 to 10 pairs of papillae are arranged in two rows.

A CASE-CONTROL STUDY ON THE RELATIONSHIP BETWEEN SCHISTOSOMIASIS JAPONICA AND LIVER CANCER

1987, 5(3):  220-223. 

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A case-control study on the relationship between scnistosomiasis japonica and liver cancer was conducted. 166 cases died of liver cancer diagnosed by Ⅰand Ⅱ during 1982 to 1983 were selected and matched pairs by age and sex residence of 1:2 with the same died number of cases of nondigestive tract cancer and 166 healthy people as well. There is a significant difference in schistosomiasis japonica between the two groups. A significant dose-response relativeship between cigarette smoking and relative risk is found. By eliminating the possible factors including smoking habit and family history of liver cancer, there exists a significant difference between schistosomiasis japonica and the occurrence of liver cancer.