Histological observations were carried out on the brains of mice inoculated intracerebrally (i.c.) with two wild type strains of dengue virus type 2. Mortalities of the infected mice were studied in parallel. The effects of serial passage in suckling mice were especially investigated.
Although a few death occurred after i. c. inoculation of both parent wild type strains which had not been passed in suckling mouse brain, the mortalities increased as the passage levels. By the tenth passage, the mortalities reached 100 per cent.
Both parent wild type strains produced no striking histological changes in the brains after i. c. inoculation. However by the fifth passage, diffused edema, extensive perivascular cuffs and abscess formation in the cortex of the brain were observed.

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A statistical comparison was carried out among 3 different parameters, i.e., egg count/volume, total egg count/sample and egg count/hour, in regards to day-to-day variations of S. haematobium egg output in midday urination. Among 3 parameters, the egg count/hour showed the most stable value. In addition, the total egg count in a urine sample was not correlated with the sample volume of the urine in the same individuals. We conclude, therefore, that the adoption of the egg count/hour was best as a parameter for a quantitative unit of intensity of infection for cohort studies where the changes of intensity of infection are monitored for a long period. The existing parameter for egg output expressed in terms of the egg count/10 ml volume of urine seems to be a less reliable reflection of the intensity of infection.

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Onchocerca volvulus microfilariae from 130 patients in 8 northern Guinea savanna villages of the Jos Plateau were stained by the naphthol AS-TR-phosphate method for the demonstration of acid phosphatase. Microfilariae were classified into 13 types according to their staining characteristics. Five corresponded to the enzyme types already reported by some workers on the West African rain-forest and Sudan savanna strains of O. volvulus. Eight types showed intense enzyme activity in the regions of the amphids and phasmids, in addition to any other structures in microfilaria.
Highly significant variations in type frequency (p<0.001) were observed between microfilariae from the summit area of the Jos Plateau and those from the villages in the northern area where the Guinea savanna shares common borders with the Sudan savanna.
The multiple enzyme patterns revealed in this study indicate that the O. volvulus microfilariae of the Jos Plateau are more polymorphic in relation to enzyme staining than the strains of the parasite from Yemen, Guatemala, Venezuela, and the West African rain-forest and Sudan savanna. A brief background of the study area is given and the significance of these findings is discussed.

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The newly-emerged females of the anautogenous blackfly, Simulium (Wilhelmia) takahasii (Rubtsov), were allowed to mate, feed on human blood and oviposit in the laboratory with an attempt to complete the multiple gonotrophic cycles. As a result, 85 of 87 inseminated flies which were fed on the blood and maintained at various constant temperatures (12°C to 28°C) oviposited, and the duration from blood feeding to oviposition tended to shorten with an increase of maintaining temperatures (i.e. median length, from 5.5 days at 12°C to 1.9 days at 26°C). The gap in time from the completion of oocyte development to oviposition gradually widened as the temperature lowered. Out of 85 flies ovipositing the first batch ofeggs, 20 were fully fed on the second blood within 17 hours, and subsequently deposited eggs. Moreover, 3 of these 20 flies took the third blood and 2 of them oviposited. The lengths ofduration from blood feeding to oviposition in the second and third gonotrophic cycles were 1.17 and 1.40 times as long as that in the first cycle, respectively. The mean number of eggs matured per fly reduced in the second and third gonotrophic cycles, as compared to that in the first. A single insemination has proved to enable this blackfly to produce fertile eggs at least over the first 3 gonotrophic cycles.

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Surveys for schistosomiasis, intestinal parasitic infections and filariasis were carried out in 3 villages of the Jos Plateau, Nigeria, in the period between February and March, 1985. Of 668 fecal samples, 66.8% were found to harbour parasitic eggs and protozoa. The overall prevalence of parasitic infections among villagers was as follows : hookworm, 40.3%; Ascaris lumbricoides, 9.1%; Strongyloides stercoralis, 0.3%; Trichuris trichiura, 0.4%; Schistosoma mansoni, 18.9%; Taenia sp., 0.1%; Hymenolepis nana, 0.1%; and cysts of Entamoeba histolytica, 6.7%; Entamoeba coli, 31.4%; Iodamoeba bütschlii, 11.1%; Endolimax nana, 2.5%; Chilomastix mesnili, 1.6%; Giardia lamblia, 1.5%. Hookworm was the predominant helminth, and the infective larvae of Necator americanus were found in 6 pupils using filter paper-cultures. The prevalence rates of hookworm infection varied significantly with villages; 53.9% at Sop, 33.3% at Jebu and 6.0% at Maigemu. Of the 344 inhabitants, 5.2% and 13.4% were found to harbour microfilariae of Loa loa and Dipetalonema perstans, respectively. Factors which may have contributed to the spread of these parasitic infections on the Jos Plateau are discussed.

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A rare complication of atrial flutter developed during a febrile attack in a man with P. vivax and P. falciparum (gametocyte only) infection. Until being infected with the malaria parasites, the patient had been in good health and had not noticed discomfort in the chest. The arrhythmia disappeared spontaneously after starting treatment with chloroquine. The possible role of P. vivax schizonts occluding capillary vessels in the myocardium is herein discussed.

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