Table of Content

28 February 1984, Volume 2 Issue 1

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INVESTIGATION AND QUANTITATIVE ANALYSIS OFTHE COMPONENTS OF VECTORIAL CAPACITYOF ANOPHELES SINENSIS

1984, 2(1):  3-8. 

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An investigation on the components of the vectorial capacity of A. sinensis was carried out in Liji Commune of Peixian County, Jiangsu Province from 1979 to 1981. and the results are given as follows: 1. The average man-biting rate of A. sinensis calculated by outdoor human bait collection was 33.0, but the rate would be 11.0, one third of the former if measured by using mosquito net after 22 o'clock. The man-biting rate from July 21 to September 10 was relatively higher, forming a peak in August. 2. Observation on blood digestion and ovary development and on the freshly blood-engorged females of A. sinensis put into vials separately for ovipositipn suggested that an average of 2.5 days was needed to complete a gonotrophic cycle, and for the first gonotrophic cycle after emergence about 3.5 days were needed. 3. A total of 11,186 inosquitos of A. sinensis have been dissected within the three years, the parous rates being 0.581-0.621, and the daily survival rate 0.856-0.873. 4. 3,755 specimens of blood meal of A. sinensis were collected from human dwellings and cattle sheds at the daytime, making the ratio of human blood-fed 17.1%; 1,273 specimens were from the bean field, the ratio of human blood-fed 2.6%. Adjusting the result with different resting places and host preference, the human blood index of A. sinensis estimated in this area was 0.104.

OBSERVATIONS ON SOME FACTORS INFLUENCING THE SPOROGONY OF PLASMODIUM YOELII

1984, 2(1):  9-12. 

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In splenectomized mice, the parasitemia reached a peak level 6 days after inoculation of 3 ×107-4.5 ×107 Plasmodium yoelii parasitised cells and remained at a high level up to 20 days within which 7 out of 10 test animals died, while all the nonsplenectomized animals survived the peak level of parasitemia by day 22.Two to four days after blood inoculation intact mice were found most infective to the anopheline mosquitoes with a gland infection rate of about 40%. The mosquitoes fed on splenectomized infected mice during the same period developed a higher gland infection rate. As the time of the experiment went on, more statistically significant differences in rates between the two groups of mosquitoes became evident (P0.001).In comparison with the control given glucose only more oocysts of the parasite developed in the mosquito vectors receiving PABA of various concentrations (0.5%, 0.05%, 0.005%) in glucose solution. 0.05% PABA was found to be most suitable for the development of the oocysts.The peak level of the infection rate of the vector fed on mice with blood induced infection varied with the time of blood inoculation. It occurred at about midnight (20:00-24:00) when inoculated at 12 o'clock; conversely, it did in the morning (8:00-12:00) when inoculated at 24:00.

SEROEPIDEMIOLOGY OF SCHISTOSOMIASIS JAPONICA I.AGE DISTMBUTION OF ANTIBODY RESPONSE IN POPULATIONS LIVING IN THREE AREAS OF DIFFERENT ENDEMICITY

1984, 2(1):  13-16. 

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A study on seroepidemiology of schistosomiasis japonica was performed by means; of IHA test with a gut-associated antigen of the adult worms among populations in one actually endemic area and two previously endemic, but now controlled areas of the infection. To explore the relationship between the age distribution of antibody response and the transmission of schistosomiasis in populations living in these areas with different endemicity, the graphic distribution curves of antibody levels according to age grouping were drawn. The age distribution curves of antibody levels in populations studied showed different patterns. It was suggested that in a given area, the level of antibody response of individuals in the youngest or younger age group could more likely reflect transmission in recent time and the analysis of antibody level of low age groups could provide a basis for evaluating whether the transmission had been interrupted or not.

ISOLATION AND 1MMUNOACTIVE CHARACTERIZATION OFTEGUMENTAL MEMBRANE PROTEINS FROM ADULTSCHISTOSOMA JAPONICVM

1984, 2(1):  21-24. 

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The integral tegumental membrane proteins have been obtained from the crude tegument membrane preparation by the extraction and removal of the water soluble proteins and other peripheral protein components with sodium lauryl sulphate. Five' membrane proteins were identified by SDS-PAGE electrophoresis with the following molecular weight: Ⅰ. 64,000; Ⅱ. 58,000; Ⅲ. 39,000; Ⅳ. 27,000 and Ⅴ. 18,700. The membrane proteins of Ⅰ, Ⅲ and Ⅳ are glycoproteins. Among these membrane proteins two components can be recognized by specific antibodies, based upon the isolation of 125I labelled immune complexes with Staphylococcus Protein A, SDS-PAGE electrophoresis and autoradiography.

A SURVEY OF ANGIOSTRONGYLUS CANTONENSISIN GUANGZHOU

1984, 2(1):  25-27. 

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A survey of Angiostrongylus cantonensis in snails, slugs, prawns, toads and rats was carried out in Guangzhou, from Feb 1981 to June 1982. The results were as follows: (1) 164 out of 10,034 Rattus norvegicus (1.6%) were naturally parasitized with Angiostrongylus cantonensis. A comparison between the parasitic fauna of three different districts in Guangzhou showed that the infected rate was higher in Yuexiu (2.3%) than in Liwan (1.2%) and Haizhu (0.3%). (2) 98 out of 330 giant African snails, Achatina Julica (29.7%) were parasitized with the third stage larvae of Angio-strongylus cantonensis. (3) In 63 Vaginufus sp. and 494 Philomycus bilineatus were recovered respectively 56,060 and 1,577 third stage larvae. (4) The role of Bufo me-lanostictus and a species of freshwater prawns, Macrobrachium nipponense as paratenio hosts for Angiostrongylus cantonensis third stage larvae could not be demonstrated

EFFECT OF PYRONARIDINE AND THREE OTHER ANTIMALARIALSON GAMETOCYTES AND SPOROGONY OFPLASMODIUM YOELII

1984, 2(1):  28-31. 

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When P. yoelii gametocyte-carrying mice administered ig with pyronaridine 1,200 mg base/kg ( LD50) were fed 2 or 12 hours later to batches of Anopheles stephensi, no affection was observed on the development of oocyst and infective sporo-zoite in the mosquitoes. Similar result was obtained in mosquitoes fed on mice medicated with chloroquine 600 mg base/kg ( LDSO). However, the formation of oocyst was inhibited when the mosquitoes were fed on mice drugged ig with 20 mg base/kg of primaquine or a larger dose of pyrimetltiamihe (10 mg/kg). When 0.005% pyronaridine was fed to the mosquitoes after their engorgement of gametocyte-blood meal, no influence on gametocyte infectivity and sporogony was noted. With 0.01% pyronar ridine most mosquitoes died of intoxication, but normal oocyst could still be found in the survivors. The result in mosquitoes exposed to ehloroquine was similar, normal oocysts being detected. In contrast, the feeding of 0.001% pyrimethamine to mosquitoes led to complete suppression of sporogony. 0.01% primaquine caused the death of many mosquitoes, but oocysts could still be found in the remainders. Primaquine inhibited the infectivity of gametocytes to mosquitoes and oocyst formation at the concentration of 0.1%, no oocyst being detected in the few survivors.

EPIDEMIOLOGICAL IMPORTANCE OF ONCOMELANIA SNAILON MARSHLANDS IN AND ALONG YANGTZE RIVER IN THE SPREAD OF SCHISTOSOMIASIS JAPONICA IN JIANGSU PROVINCE

1984, 2(1):  32-35. 

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In the 50s' and 60s' shoals and marshlands with a high snail density and a large number of infective snails were widely distributed in the Yangtze River and the lakes in Jiangsu. The spreading of the snails from these areas to the surrounding and lower reaches was found to be serious.It was the main focus of acute schistosomiasis infections and closely related to the maintenance of schistosomiasis in the plain region with network of water ways. After more than twenty years schistosomiasis control, especially in the 70s', the distribution of the snail-infested areas was greatly reduced. However, the Yangtze River was flooding in recent two years, distribution of snail-infested areas was found to be extended as compared to the end of the 70s'. These shoals became very important in the epidemiology of schistosomiasis in Jiangsu. Because of the particular situation of the lower-readies of the Yangtze River and the serious spreading of the snails in these areas, much attention must be paid to these areas in Jiangsu Province for a long period of time.

ANALYSIS OF THE SOLUBLE ANTIGENS IN THEPERITONEAL EXUDATE OF MICE INFECTEDWITH TOXOPLASM A GONDII

1984, 2(1):  36-38. 

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Peritoneal exudate collected from mice infected with Toxoplasma gondii was centri-fuged at 15,000 rpm (4℃) for 60 minutes, the supernatant is the soluble antigen (S), The sediment, a mixture of parasites and host's cells, was suspended in distilled water and disrupted by ultrasonication at 330 mA for 5 minutes. After adding equal volume of 1.7% Nacl, the suspension was centrifuged at 15,000 rpm (4℃) for 60 minutes, and this supernatant is the disrupted body antigen (DB). Antigen S1, S2 and S3 were obtained from antigen S by precipitation with 30%, 60% and 100% ammonium sulfate respectively, and further purified by Sephadex G-100 gel filtration. Using double diffusion, rocket immunoelectrophoresis and polyacrylamide gel electrophoresis, it appears that antigen DB is superior to antigen S in its sensitivity, but it lacks the specific soluble component. The preparation of antigen S is rather simple. S1 contains both the specific soluble component and the component identical with antigen DB. Therefore, S1 is recommended to be further purified for experimental purposes.

STUDY ON AN AGAR GEL DIFFUSION METHOD FOR THE IDENTIFICATION OF MOSQUITO BLOOD MEALS

1984, 2(1):  39-42. 

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Agar gel diffusion was carried out in this study to identify the host source of mosquito blood meals. For comparison, the precipitin ring test was done simultaneously.For the agar gel diffusion test, optimal concentrations of antigen and amiserum, optimal temperature and reaction time were determined. Specimens of blood meals of Anopheles sinensis artificially fed on the fresh cattle blood through a membrane and from fields were collected and tested. It was demonstrated that when the dilution of antigens was 1:500-1:1000 and that of antiserum 1:4, and the 'test performed at 24-37℃ for 24 hours, the results were consistant with those of precipitin ring test. However, in the latter test, 7.8% of the specimens cross-reacted with horse and sheep. It appears that the agar gel diffusion test is more advantageous over the precipitin ring test in terms of its higher specificity for identification of mosquito blood meals. This method is also simple to perform.

AGGLUTINATION ACTIVITIES OF LECTINS ON VARIOUS STRAINS OF LEISHMANIA PROMASTIGOTES

1984, 2(1):  43-45. 

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The agglutination activities of concanavalin A, phytohemagglutinin, wheat germ agglutinin and Ricinus communis agglutiiiin on five strains of Leishmania donovani, one strain of L. mexicana amazonensis, one strain of L. gerbilae and one strain of L. sp. isolated from lizards were studied. Con A and RCA agglutinated specifically all the eight strains. Agglutination with PHA or WGA did not occur in any of the strains tested. These results showed the presence of terminal ligands as α-D mannose and/or a-D glucose and a-D galactose on the surface membrane of these strains of Leishmania.

PRELIMINARY CLINICAL OBSERVATIONS ON FURAPYRIMIDONEIN THE TREATMENT OF DIPETALONEMA PERSTANSAND LOA LOA FILARIASIS

1984, 2(1):  49-51. 

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From May 1981 to August 1982, clinical observations were made on 8 cases of Dipetalonema perstans and 1 case of Loa loa microfilaremia returning from Equatorial Guinea and treated with a total dosage of 200mg/kg of furapyrimidone in 10 days. The daily dose was divided into 3 portions given orally. In cases of Dipetalonema perstans microfilaremia, the rates of clearance for blood microfilariae 1 day, 6 months and 14 months after the completion of treatment were 0, 60% (3/5) and 88% (7/8) respectively, and microfilariae reduction rates were 63.8%, 96.0% and 98.3%, while in the case of Loa loa, microfilaremia was negative immediately after treatment, but returned to positive 6 months later. The result showed that with the above-mentioned dosages, furapyrimidone is more effective against Dipetalonema perstans, especially against the adult worms, since the rates of clearance for blood microfilariae were higher with the time.