Table of Content

31 August 1989, Volume 7 Issue 3

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IN VIVO SENSITIVITY OF PLASMODIUM FALCIPARUM TO PIPERAQUINE PHOSPHATE ASSAYED IN LINSHUI AND BAISHA COUNTIES, HAINAN PROVINCE

1989, 7(3):  163-165. 

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Fifty-three cases of falciparum malaria in Linshui County, Baisha County and Sanya Municipality were treated with piperaquine phosphate at a total dose of 1.5gbase over 3 days in July to December, 1986. The mean defervescence time was 36±20.7h; the mean asexual parasite clearance time was 69.7±20.9h. At 14-28d follow-up lecrudescence was observed with asexual parasitemia in 7 of the 47 cases, showing RI resistance to piperaquine. Gametocytemia was positive in 35 cases (74.5%) during the follow-up period.

IMMUNOLOGICAL HUMORAL RESPONSE IN MICE EXPERIMENTALLY INFECTED WITH ECHINOCOCCUS GRANULOSUS, PRELIMINARY RESULT OF KINETIC OBSERVATION

1989, 7(3):  170-173. 

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5 serological methods included latex agglutination test (LA), enzyme-linked immu-noelectrotransfer blot (EITB), enzyme-linked immunosorbent assay(ELISA), dot-enzyme-linked immunosorbent assay (Dot-ELISA) and immunofluorescence antibody test (IFA) were used to trace tne kinetic changes of the humoral response in NIH mice experimen-tally infected with protoscolex of Echinococcus granulosus. Results showed that Dot-ELISA and IFA were able to detect antibodies 2 wk after infection while ELISA, EITB and LA gave positive reactions 4 wk, 2 mos and 3 mos after infection respectively. Therefore Dot-ELISA and IFA were considered to be the most sensitive ones among the 5 methods used. All infected mice gave positive reactions at 8 and 12 mos but none of the normal control mice showed any reaction throughout the period of observation (Fig. 1).

A PRELIMINARY STUDY ON DETECTING PLASMODIUM FALCIPARUM IN BLOOD BY PLASMODIUM FALCIPARUM DNA PROBE

1989, 7(3):  174-176. 

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A simple and rapid method for detecting Plasmodium falciparum in human blood was used in this study. The assay is based on DNA-DNA spot hybridization. For this purpose, the total genomic DNA of P. falciporum was isolated and purified from the parasite cultured in vitro. Then the total genomic DNA was used as a probe and labelled with [α-32P]-dATP by nick-translation. Twenty-five test samples, ten-microliter lysed infected blood each, were spotted onto dry nitrocellulose paper and hybridized with labelled genomic DNA. After hybridization, the paper was exposed to X-ray film for autoradiography, resulting in an image in places where hybridization occurred.The result shows that the assay appears to be sensitive enough to detect parasitaemia up to 0.0009%. No visible hybridization was detected in normal human blood or human leukocytes. Many samples can be processed simultaneously. This may be applicable to mass survey for detecting P. falciparum in epidemiological study (Fig. 2).

PREDICTIVE IMPACT ON MALARIA PREVALENCE BY HYDRAULIC PROJECT OF THREE GORGES OF THE YANGTZE RIVER

1989, 7(3):  177-180. 

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Malaria had a wide distribution and high prevalence throughout the Three Gorges region of the Yangtze River. After antimalarial program, its incidence rate was reduced to 2.2‰。 in 1985, but sporadic cases still occurred in 34.7% of the townships and local outbreaks were not uncommon. Therefore, potential factors of malaria outbreak are still present.It is predicted that maximum risk of malaria outbreak will take place, during con-struction and after the completion of the reservior, the breeding sites of Anopheles would be extended to irrigation network, low-lying of flooded land, and malaria preva-lence might be increased.

EXPERIMENTAL STUDIES ON THE INCUBATION PERIOD AND RELAPSE PATTERNS IN VIVAX MALARIA IN WEST HUNAN

1989, 7(3):  181-183. 

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The paper reports on some biological characteristics of Plasmodium vivax isolated from Cili County of Hunan Province.27 volunteers inoculated with sporozoites were observed for 1.5 to 2 years. Treat-ment with chloroquine 1.5g base for 3 days was initiated on tne first day of tne pri mary attack and of each relapse.The data indicate that tne first latent period in 13 cases developing malaria after short incubation period is very long, being 243.4 (191-297) days; however it is always short, being 55.3 (51-80) days in 14 patients with long incubation period. Definite relationship existing between incubation period and relapse patterns in vivax malaria is thus demonstrated.

FIELD OBSERVATION ON THE RELAPSE PATTERN IN PATIENTS NATURALLY INFECTED WITH VIVAX MALARIA FROM SPRING TO AUTUMN SEASONS IN CILI COUNTY, HUNAN PROVINCE

1989, 7(3):  184-186. 

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215 patients of vivax maltria were treated with chloroquine phosphate alone at the dose of 1.5g for three days from April 1986 to October 1987 in Cili County in the northwest part of Hunan Province. Among them, 58 cases relapsed, the relapse rate being 27.0%. In patients admitted in April and May, as judged from the interval bstween treatment and the first relapse, the latent period was short, between 60.8d and 63.5d. On the contrary, when chloroquine treatment was given in August and September, the latent period in all the patients was long, between 292.4d and 297.5d. It is very inte-resting to note that in patients treated in June and July, both long and short latent periods occurred. 72.7 % of the patients treated in June had short latent period (63.7d), while 75.0% of the patients treated in July had long latent period (285.4d).

FURTHER STUDIES ON THE MONGOLIAN JIRD MODEL OF GIARDIA LAMBLIA

1989, 7(3):  187-190. 

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Seventy-seven Meriones unguiculatus were inoculated imraesophageally with Giardia lamblia cysts isolated from the stool of a Giardia infected child. Correlation between oral dosage, course of infection, trophozoite distribution and the pathological changes in the small inustine of the infected jirds were studied. One (12.5%) of eight animals became infected with only 5 cysts. 104 cysts/jird or more was infective to nearly all the animais. Most of the infected animals (83%) excreted cysts and/or trophozoites intermittendy. The extent of trophozoite colonization and their distribution in the small intestine varied with the time of infection, but not with the number of Giardia found in the feces. There was no direct correlation between the size of inoculum and the course of infection, the fecal output of cysts and/or trophozoites, or the intensity of pathological changes in the small intestine. The histopathological lesions induced by G. lamblia included cellular infiltration of the mucosa of the small bowel, nodular lymphoid hyperplasia, edema of the lamina propria and increase in mucous secretion. Necrobiosis and shedding of the epithelium was evident, and the mitotic figures of intestinal crypt increased significantly. The reduction of the villi to crypts ratio may indicate that the villi of small intestine were covered by relatively immature entero-cytes, which may, partially, account for the malabsorption in giardiasis (Figs. 1-3).

USE OF DOUBLE McAb SANDWICH ELISA TO DETECT CIRCULATING ANTIGEN OF TOXOPLASMA IN INFECTED RABBITS

1989, 7(3):  191-193. 

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This paper reports on the cumulative positive frequencies of circulating antigen (CAg) detected in the sera of rabbits infected with Toxoplasma by using double-McAb sandwich ELISA. The positive frequencies of rabbits with heavy and medium infection in the incubation period are 30.8% and 11.1%. Those with medium infection in acute, subacute and early chronic period are 86.1% and 76.7%, 43.3% and 32.0% with light infection. The positive rates of CAg in rabbits of medium and light infection rose progressively in acute period, but declined in subacute and early chronic period. Cross reaction with schistosomiasis and coccidiosis was all negative. This method of high specificity, sensitivity and duplicability possesses certain value in the diagnosis of acute or active Toxoplasma infection and may be useful for the diagnosis in .the early period.

CHANGES IN ANTIOXIDATIVE SYSTEM IN ERYTHROCYTES INFECTED WITH PLASMODIUM FALCIPARUM

1989, 7(3):  194-196. 

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In order to probe into the redox state in erythrocytes infected with P. falciparum, parasites of Hainan strain (FCC-1/HN) were cultured in vltro and trophozoites and schizonts were obtained by Percoll gradient separation. The effects of P. falciparum infection on antioxidative system and active oxygen level in erythrocytes were studied. It was found that the activities of superoxide dismutase, catalase and the content of reduced glutathione in infected erythrocytes were markedly decreaced, while the activities of glutathione peroxidase and glutathione reductase in infected erythrocytes remained unchanged. There was no evident increase in superoxide in infected erythrocytes. How-ever, the Lvel of hydro en peroxide in infected erythrocytes was markedly increased.

AVIDIN-BIOTIN-PEROXIDASE COMPLEX ENZYME-LINKED IMMUNOSORBENT ASSAY IN THE DIAGNOSIS OF HUMAN MULTILOCULAR ECHINOCOCCOSIS

1989, 7(3):  197-200. 

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The Avidin-Biotin-Peroxidase Complex enzyme-linked immunosorbent assay (ABC-ELISA) with antigen from gerbils infected with alveolar hydatid (GAH) was performed on the sera of 54 patients with multilocular echinococcosis, 107 patients with other diseases and 102 healthy adults. All the sera were diluted 1:200 and an S/N value≥2.2 was taken as positive. Both the sensitivity and specificity were 98.1%. The S/N value (mean ± SD) of sera of the patients with multilocular echinococeosis, other parasitic diseases, tuberculosis, other diseases and healthy adults were: 5.9±3.0, 1.1±0.4, 1.4 ± 0.8, 1.1±0.5 and 1.0 ± 0.4. The geometrie mean titre (GMT) of antibody measured by ABC-ELISA was 13.7 times that of ELISA. The quantity of serum used in ELISA was 8 times that of ABC-ELISA. ABC-ELISA might be particularly helpful to identify cases with low immune responsiveness.In the detection of alvcolar hydatidosis and cystic disease with GAH antigens, the positivity was 98.1 and 67.1% with 87 and 25.6% having S/N5, respectively. It is suggested that in the diagnosis of hydatid diseass by ABC-ELISA, homologous antigen should ba used. The tempsrature and the incubation time needed for the present assay are practical, for the total time requires only 55 minutes.

COMPARISON IN SUSCEPTIBILITY OF ANOPHELES DIRVS AND ANOPHELES STEPHENSI TO B STRAIN OF PLASMODIUM CYNOMOLGI

1989, 7(3):  201-203. 

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This paper reports on the comparative susceptibility of A. dirus (Hainan strain) and A. stephensi (Hor strain) to the B strain of P. cynomolgi in paired feeding experi-ments. In the most susceptible infective period, the infection rate in midgut and salivary gland of the two species was over 90 %, the difference is not statistically significant.In relatively infective period, three experiments were performed, the infection rate in midgut of A. dirus was 24.4-60.4% with an average of 46.5% (53/114), and that of A. stephensi was 11.5-21.1% with an average of 14.2% (16/113). Statistically, experiment I showed no significant difference, the difference in experiment n was highly significant (P0.01), and that in experiment JI was significant (P0.05). The number of oocysts in A. dirus was three times over that in A. stephensi. The infection rate of salivary gland in A. dirus was 18.2-55.0% with an average of 30.6% (19/62) and that of A. stephensi was 6.7-14.3% with an average of 9.5% (6/63). Statistically, only one of the three experiments showed significant difference (P0.01). The result suggests that the susceptibility of A. dirus is higher than that of A. stephensi to the B strain of Plasmodium cynomolgi.

ULTRASTRUCTURAL STUDIES ON THE SPERMATOGENESIS IN DIPLOID AND TRIPLOID TYPES OF PARAGONIMUS WESTERMANI

1989, 7(3):  204-206. 

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Diploid and triploid types of Paragonimus westermani were compared in the aspect of ultrastructure of spermatogenesis. The results showed that the process of spermatoge nesis in the diploid type was normal. The cells at every stage are well developed. A great number of morphologically and functionally normal spermatozoa could be formed. On the other hand, the process of spermatogenesis in the triploid type was abnormal, the cells at every stage developed abnormally. They were apparently degenerated or va-cuolated, lacking organelles. The cytophore was broken into small particles. No normal spermatozoa were found (Figs. 1-5).

PRELIMINARY OBSERVATION ON FEEDING PREFERENCE OF ONCOMELANIA FOR SEDUM SARMENTOSUM

1989, 7(3):  207-209. 

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As a result of screening, we discovered that Sedum sarmentosum Bunge was most preferred among 317 kinds of snail food. Both adult and young snails readily eai S, sarmentosum as evidenced by laboratory observation and dissection of the snails.In aquarium, more snails were attracted by S. sarmentosum than by Chunese cabbage and Chlorella suspension. On water surface, S. sarmentosum curtains attracted adult snails 2.l-3.7 times and immature snails 2.3-4.1 times more than rica straw curtains.

A COMPARISON OF THE EFFICIENCY OF DENSITY GRADIENT AND LOW-SPEED CENTRIFUGATION METHODS FOR ISOLATING PLASMODIUM SPOROZOITES

1989, 7(3):  210-212. 

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P. yoelii sporozoites(Sp) in Anopheles stephensi were first isolated with low-speed centrifugation and the Sp suspension was subsequantly purified with the density gradient centrifugation. The recovery rates of Sp by the latter method is about 50-75% of that by the former, but few debris could be found in the Sp suspension and the infectivity of the Sp was not weakened as compared with the Sp obtained by low-speed method. Sp would retain partial infectivity, when its suspension was maintained ia medium 199 at 4℃ for 48 hrs. When rats and mice were infected with these Sp, patho-logical changes of hepatocytes such as cloudy swelling or fatty degeneration, which had been evidenced to be induced by mosquito tissues, would be absent or present in th slightest degree.

ULTRASTRUCTURAL OBSERVATION ON THE BODY WALL OF PAGUMOGONIMUS SKRJABINI

1989, 7(3):  213-214. 

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This paper deals with the ultrastructure of the body wall of adult Pagumogonimus skrjabini by transmission electron microscopy. Infected crabs were collected from Siyen, Hubei Provine, and adult worms were obtained from the lungs of experimentally infected dogs 90 days post-infection.The normal structure of body wall of the P. skrjabini is composed of tegument, tegument cell, musele, muscle cell and protoplasmic tubules, all of which form together syncytium.The tegument contains external plasma membrane, tegument matrix and basal plasma membrane. The cell coat in fine granules is distributed over the whole external plasma membrane surface. The tegument matrix contains various secretory bodies, vesicles and mitochondria. The tegument cell is irregular in shape. Golgi complex, ribosome, autoly-sosome are seen in the cytoplasm. There are two layers of muscle, the external circular muscle and the inner longitudinal muscle layers. The nucleus of immature muscle cell has many heterochromatins, while the nucleus of mature muscle cell is large and round in shaps. Mitochondria and glyco-gen granules are transmitted from muscle cell proper to the muscle by protoplasmic tubules (Figs. 1-7).