Suramin, a polysulfonated naphthylurea, has been used for the treatment of trypanosomias and onchocerciasis, and is a potent inhibitor of nucleic acid polymerase including reverse transcriptase and DNA polymerase. This drug is used to examine an antiviral activity in the case of Japanese encephalitis virus (JEV) infection. Japanese encephalitis occurs in endemic and epidemic form over a wide area of Asia, at least tens of thousands of cases occur annually in East Asia. Although the vaccine against JEV is widely used, we have no antiviral drugs against JEV replication. Here we describe an antiviral activity of suramin on JEV replication in the cultured cells. In the presence of 50 μg/ml suramin, virus yields in human neuroblastoma cell line, IMR-32, reduced to 0.1% of control level. JEV growth in human hepatoma cell line, HepG2, was also inhibited, but inhibitory effect of suramin was lower than in IMR-32. The difference of inhibitory effects between host cells suggests that some host factors were involved in the process of inhibition of JEV growth. By Western blot analysis, it was clarified that expressions of JEV proteins, NS3 and E were markedly reduced by the treatment of suramin at 50-200 μg/ml. Especially the expression of E protein seems to be sensitive against suramin treatment. On the other hand, JEV-RNA level in the cells treated with suramin was not so different from control level, and in vitro JEV-RNA synthesis was also not inhibited by the addition of suramin. These results suggest that suramin inhibits virus replication through the influence to viral protein production, not to viral RNA synthesis.

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An epidemiological survey was done by examining 1084 inhabitants in a rural area of Guatemala to determine the prevalence of seropositivity to Trypanosoma cruzi as well as the association with chagasic cardiomyopathy. Results of the survey revealed that Chagas disease is endemic in this area because 77 (7.1%) of the inhabitants examined by an indirect hemagglutination test were seropositive to T. cruzi. The age-prevalence distribution showed that seropositivity increased with age. Analysis of electrocardiogram (ECG) revealed a significantly high frequency of ventricular conduction defects and arrhythmias among the seropositives. Ventricular conduction defects were observed in 18.2% of the seropositives and 1.7% of the seronegatives, and arrhythmias were 15.6% and 2.7%, respectively. In seropositive individuals, the most common alteration of ventricular conduction defects was right bundle branch block with or without fascicular block and that of arrhythmias was ventricular premature contraction. Among the seropositives, the prevalence of the above ECG abnormalities was low in the 40-59 age group, which may be accounted for the death due to chagastic cardiomyopathy. These results suggest that this study area is an endemic area to Chagas disease, and the infection is associated with ECG alterations.

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The geographical distributions of the genus Simulium Latreille s.l. in the Oriental and Australasian Regions were mapped. The patterns of distribution were examined at the subgenus and species-group levels. Among the 11 subgenera recorded in these regions, five (Byssodon, Eusimulium, Montisimulium, Nevermannia and Simulium s.str.) were essentially Palaearctic, apparently penetrating to varying extents from the north to the Oriental Region and two of which were further extending their eastward ranges up to the Australasian Region; while the other six subgenera (Gomphostilbia, Hebridosimulium, Himalayum, Inseliellum, Morops and Wallacellum) were nearly endemic to the Oriental or Australasian Regions or both. All the endemic subgenera, except Himalayum, had their own center of development and distribution on the islands. Eight of 12 species-groups of Simulium s.str. were mostly confined to the Oriental Region, and five of which demonstrated a definite insular pattern in their distribution. The probable dispersal routes were inferred for several species-groups of the subgenera Nevermannia and Simulium s.str. The Simulium faunae of the Philippines, Sulawesi and the Maluku Islands present a mixture of the Oriental and Australasian elements but the faunal break is likely to be seen on both sides of the Weber's Line.

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Color variations of legs (in particular hind femora and tibiae) were observed in female Simulium aokii (Takahasi, 1941) caught monthly at cattle shed in Oita, southwest Japan. Female flies were collected from November to April but not during warm and hot months (May to October). Female flies with legs darker than normal began to appear in the mid autumn (November) and increased in relative abundance up to the mid winter (January), and then decreased gradually until the mid spring (April). The intensity of darkness on both hind femora and tibiae varied similarly, with the darkest in January. During these cool or cold months, there was a positive correlation between the relative size of dark area on the tibia and the wing length. From these results the species status of S. aokii was discussed in relation to S. oitanum originally described from Oita.

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