Description was given on the material and procedure of the nylon mesh filtration technique for quantitative detection of helminth eggs in the feces, and comparison was made between the filtration and the Kato-Katz techniques on the clearness and preservation of detected eggs and the efficiency of detection. In the filtration technique, fecal matter is filtered through nylon mesh to concentrate the eggs and the eggs are sealed in the mounting medium by melting the mesh fibers. This technique can detect all the helminth eggs including hook worm and small Clonorchis eggs that are difficult to be recognized by the Kato-Katz technique. The rate of coincidence of the positive and negative slides of Schistosoma eggs between the two techniques was 88.7%, being statistically high. The filtration technique can detect 2.4 times number of eggs that are collected by the Kato-Katz technique, and the sealed eggs are clear enough to identify and can be preserved for months. This filtration technique, simple and suitable for field use, can contribute to find the helminth infections and to evaluate the control work even in developing countries.

View full abstract

Tetracyclines are used for prophylaxis of malaria and treatment of drug-resistant falciparum malaria because of their safe drug action. We re-evaluated effects of three tetracyclines against drug-resistant Plasmodium falciparum in vitro. Minocycline was approximately 4 times and twice more potent in inhibiting the in vitro growth of falciparum parasites than tetracycline and doxycycline, respectively. Compared with doxycycline, significant inhibitory effects of minocycline to chloroquine, pyrimethamine and mefloquine resistant P. falciparum strains were affirmed by the present in vitro study. By electron microscopy a number of electron dense vesicles with a single membrane bound were observed in the cytoplasm of minocycline-treated parasites, although no distinct structural alternations of mitochondria was noted. Minocycline may be a better therapeutic drug than doxycycline which is widely accented as the standard antimalarial tetracycline.

View full abstract

Simulium weji sp. nov. is described based on the reared females, reared males, pupae and mature larvae collected from Tharn Thong Waterfall in Lampang Province, Thailand. This new species is assigned to the tuberosum species-group within the subgenus Simulium s. str., and seems to be closely related to S. rufibasis Brunetti and four other allied species, reported from India and Thailand, by having a pair of hair clusters on the ventral surface of the seventh abdominal segment of the female, which are, though, much longer and fewer in this new species. This new species seems to be also related to S. nigrifacies Datta from India and S. puliense Takaoka from Taiwan, by having the similar arrangement of six short pupal gill filaments, but is easily differentiated from these known species by the small cone-shaped tubercles on the head and thoracic integuments.

View full abstract

The mechanisms of antigen-uptake at the host mucosal barrier during infection with lumen-dwelling intestinal parasites have not been well elucidated. In this study, we investigated immunolocalization of parasite excretory/secretory (ES) products in the small intestinal epithelium of rats infected with Nippostrongylus brasiliensis. Immunoelectronmicroscopy revealed intense ES immunoreactivity in the absorptive cell cytoplasm in association with lysosome-associated membrane glycoprotein (LAMP-1), and in the paracellular spaces. These results indicated that nematode antigen could be absorbed by two pathways : absorption by endocytosis and transport to lysosomes, and absorption through the paracellular pathway, suggesting altered mucosal barrier function.

View full abstract

IgE-inducing potential of excretory/secretory products (ES) of the nematode Nippostrongylus brasiliensis was examined in mice immunized with ES without use of adjuvant. Repeated i.p. injections or continuous i.p. or s.c. infusion of ES induced significant increases in total serum IgE. Continuous i.p. or s.c. infusion of ES also induced ES-specific IgE antibody, while repeated i.p. injections did not. IL-4 production was increased by ex vivo stimulation with ES of mesenteric lymph node cells from repeatedly immunized mice.On the other hand, continuous intraduodenal infusion of ES induced neither total nor specific IgE responses. These results suggest that continuously secreted ES from the nematode are relevant for the up-regulation of IL-4 and IgE responses, although additional factor (s) may be necessary for the uptake of ES across the intestinal mucosal barrier.

View full abstract

The AnaeroPack (AnP) system (Mitsui Gas Co., Japan) was produced for the purpose of culturing anaerobic bacteria. The idea using AnP Campylo® for cultivation of Plasmodium falciparum and its successful results were firstly reported by Haruki et al. (1997). In the present study, characterisation of 3 products of AnPs, i.e., AnP CO₂® (at a gas phase of 5% CO₂ and 15% O₂), AnP Campylo® (10% CO₂ and 10% O₂) and AnP Plas® (5% CO₂ and 5% O₂), in an AnaeroPack Box Jar® (22×16×10.5 cm) was studied comparing with conditions in a gas incubator or gas chamber (4% CO₂ and 3% O₂) and in a candle jar (5% CO₂ and 15% O₂). The growth curves of malaria parasites showed no difference among these four conditions by incubation for 48 hr except for AnP Plas. The observed IC₅₀ levels of chloroquine were varied much by the difference of AnPs, gas phases, the pressure in a Box Jar and free space inside. For stabilisation of IC₅₀ testing, free space in a Box Jar should be kept equal and minimal by placing the maximal 5 test plates by adding dummy plates. By the stable results of IC₅₀, gas phases can be divided into two groups. The one involves the gas incubator, AnP Plas® and AnP Campylo®, and the other does the candle jar and AnP CO₂®. Results of chloroquine sensitivity test in the candle jar group showed more drug sensitive than in the gas incubator group. These two groups should be used properly by the purpose of field experiments. The AnP® system is proven to be a practical tool for malaria culture in the field for occupying only a small space in an incubator.

View full abstract

We examined specimens of adult Paragonimus westermani collected from Thai leopards by Daengsvang et al. in 1964. The two flukes examined had a six-lobed ovary each and singly-spaced cuticular spines. The seminal receptacle and seminal vesicle were filled with spermatozoa. Based on morphological features, these flukes were identified as the diploid type of P. westermani. The testis branched out into six lobes on the ovarian side and into five on the opposite side in both specimens. Abnormal branching in the testes, that is, separation of one lobe from the others and its direct connection to the was deferens, which was found in adult P westermani from the Philippines, was undetectable.

View full abstract

We studied the ultrastructure of excysted metacercariae of Paragonimus westermani from Malaysia and the Philippines using scanning electron microscopy. The body surface of the excysted metacercariae was covered with numerous single-pointed and thorn-like tegumentary spines. Dome-shaped papillae were evenly distributed over the whole body and situated circularly around the oral and ventral suckers. Between six to eight and seven to nine small dome-shaped papillae were observed around the ventral sucker in P. westermani from Malaysia and the Philippines, respectively. In general, the morphological features of the worms from Malaysia and the Philippines were identical.

View full abstract