Surface characteristics of microfilariae and developing stages of Brugia pahangi in its natural vector, Armigeres subalbatus were assayed using fluorescein isothiocynate conjugated lectins. The following lectins were used : wheat germ agglutinins, lentil agglutinins, Helix aspersa agglutinins, Concanavalin A agglutinins, kidney bean agglutinins, asparagus pea agglutinins and pea nut agglutinins. It was observed that developing stages of B. pahangi the mosquito showed a dynamic surface carbohydrate characteristics. The larvae change their surface coat configuration frequently during the 10 day observation period. However, blood dwelling microfilariae and fully matured infective larvae obtained from the mosquito's head showed little or no binding affinity for the lectins tested. It's postulated that the rapid turnover of the surface carbohydrates, while development of the larvae is taking place, is the worm's response to a 'hostile' mosquito environment.

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Surface lectin binding characteristics of microfilariae and developing stages of Brugia malayi in Armigeres subalbatus are presented. Ar. subalbatus is not a vector of B. malayi. The following lectins were used : wheat germ agglutinins, lentil agglutinins, Helix aspersa agglutinins, Concanavalin A agglutinins, kidney bean agglutinins, asparagus pea agglutinins and pea nut agglutinins. Frequent change in surface carbohydrate moieties on developing stages of B. malayi was observed. However, blood dwelling microfilariae and mature infective larvae showed little binding affinity for the lectins tested. It is postulated that B. malayi larvae evaded the mosquito immune system by continuously changing their surface carbohydrate moieties.

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The host-parasite relationship between Thai lung fluke, Paragonimus heterotremus, and laboratory animals was investigated by using rats, Rattus norvegicus, and mice, Mus musculus, inoculated with the metacercariae. It was found that both animals played roles as paratenic hosts of the fluke, but rats seemed more susceptible to the fluke than mice. In addition, juvenile flukes recovered from the skeletal muscles of the animals were able to develop into adults when transferred orally to cats.

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In order to know the basic nature of the various color mutants of the gerbil as the susceptible host to filarial infection, the growth curve as well as food and water consumption volume and reproduction rates were compared among coat color mutants of the Mongolian gerbil, such as agouti, white spotted-agouti, albino, black and white spotted-black type mutants.
There was almost no significant difference in growth curve and reproduction rates among the color mutants. Namely, mean weights of these newborns and of matures among these gerbils were 3.0 g, and 60 g in male or 52 g in female respectively, and the mean number of newborns among mutants was 4.2 to 4.8. However, the periods of delivery among these mutants varied to wide ranges. As the reasons of the change of the delivery periods, it was considered that the post-partum oestrus occurred in some of the gerbils, and in these gerbils, the delayed implantation of the placenta were seen relatively often and also in some gerbils, the irregular oestrus cycle was existed.
In addition, some genetic studies on coat colors were carried out. It appeared that some genes controlling coat colors exist in the gerbils as in mice or rats, and it suggested that albino and black colors are controlled by autosomal ressesive genes.
The coat color mutants of the gerbils also will be useful animal as the susceptible host to filarial infection.

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The two monoclonal antibodies which were raised by Paragonimus ohirai antigens and recognized the different tegumental antigens, were tested for reactivity with other Paragonimus species, P. westermani and P. miyazakii, and with other various helminth parasites, especially trematodes (Fasciola sp., Schistosoma japonicum and Clonorchis sinensis). The monoclonal antibody (MS-Mab) recognizing the tegumental antigen present from the metacercaria to adult stages, reacted with the crude antigens of other Paragonimus species. The reactive antigens were localized on the tegumental syncytium and tegumental cells, as previously reported in P. ohirai. On the other hand, the other monoclonal antibody (AS-Mab) recognizing the adult main tegumental antigen reacted only with P. ohirai antigen. These two monoclonal antibodies did not react with any other helminth adult antigens examined. It is concluded that MS-Mab is genus-specific whereas AS-Mab is species-specific.

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Sera were taken at random intervals from a Japanese patient during the acute to convalescent phases of falciparum malaria. Western blotting study revealed that the 47kD antigenic polypeptide of the parasite was strongly presented by the sera taken during the acute phase of the infection, while the 47kD band became faint as the phase progressed, and serum taken 2 months after the onset of the disease was only weakly reactive to the molecule. During the observation period, the indirect fluorescent antibody titer invariably persisted at 1 : 256. The reactivity of the serum samples taken at hypo, meso and hyperendemic localities in Sudan was tested by the same method. Regardless of the endemic backgrounds, sera from examinees with currently existing parasitemia or high antibody titers measured by an avidin biotin peroxidase complex enzyme-linked immunosorbent assay (ABC-ELISA), reacted to the 47kD antigenic polypeptide, whereas low-titered sera did not present the 47kD band. Some high-titered sera from the meso or hyperendemic locality showed no reactivity to the 47kD antigen. It was presumed that the high antibody titer of this group was a reflection of accumulated past malaria infections but not of currently active malaria or recent past infection. The 47kD molecule is a useful parasite antigenic polypeptide in terms of defining present and/or recent past infection in the serological survey of malaria.

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Trypanosoma cruzi amastigotes derived from fibroblast cultures and from cell-free liquid medium were comparatively evaluated as solid-phase antigens of ELISA for Chagas' disease. Amastigotes were obtained from the high-and low-virulent clones of the Tulahuen strain and from the G-1 strain. They were sonicated and directly applied into wells of a microplate to use insoluble particles as antigens. Fifty-one sera from patients of Chagas' disease including one acute case (with Romana's sign), 10 sera from patients of cutaneous leishmaniasis including one serum of mixed infection with Chagas' disease and 10 sera from patients of toxoplasmosis including three of mixed infection with either Chagas' disease or leishmaniasis were examined. All amastigotes from different sources and from different clones or strains showed considerable correlation with each other. Slightly higher sensitivity was found in amastigotes of high-virulent clones and slightly higher specificity in those from cell-free culture. One acute case was detected as positive by these methods although it was negative by the usual ELISA using epimastigotes.

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Giardia lamblia cysts were found in the stool of 25 patients for health screening and in 3 inpatients at the laboratory of the Fujieda City Shida General Hospital, Shizuoka Prefecture from March 1988 to December 1989.
Epidemiologic investigation showed that there are no the common source such as drinking water, travel or animal contact. It may be given as a conclusion that human giardiasis in Fujieda and its neighboring towns are indigenous and the transmission appears mainly to occur from person to person.

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