Helper T cell cytokine and antibody responses were investigated in mice after infection with Babesia microti (King strain). Infection of CBA mice with 106 parasitized erythrocytes resulted in the development of a transitory high parasitaemia which peaked 14 days post infection (DPI), and was resolved at 24 DPI. Th1 responses were activated predominately during the acute phase (6-18 DPI) whereas Th2 responses predominated during the recovery phase (14-28 DPI) as detected by the reverse transcriptase polymerase chain reaction. Increased expression of Th1 cytokines was first detected at 6 DPI (IL-2) and 8 DPI (IFN-gamma) and their peak levels were reached at 12 DPI. After the peak levels were reached, they progressively declined and fell to baseline levels (22 DPI). Increased expression of Th2 cytokines (IL-4 and IL-10) first appeared at 14 DPI, peaked at 20 DPI and Th2 cytokine levels were elevated till the end of the study (28 DPI). Levels of serum IFN-gamma detected by a sandwich ELISA correlated well with IFN-gamma gene expression and were detectable at 8-18 DPI. IgM against B. microti was first detected in serum by ELISA at 4 DPI, and peaked at 10 DPI. The levels of IgM subsequently declined but remained positive at low titre till the end of study. IgG against B. microti was first detected at 8 DPI and peak levels were reached at 24 DPI and remained at that level until the end of study. The results of the present study show that Th1 cytokines predominated in the early inflammatory response and might be involved in control of levels of acute parasitaemia whereas the Th2-associated responses, including expression of IL-4 and IL-10 and the production of parasite-specific IgG, might be the functional means for the reduction and clearance of the parasite from the body. It was concluded that an effective vaccine against Babesia spp. should be designed to induce Th1 responses to maintain the parasitaemia at unfulminating levels and also maintain Th2 responses to clear the parasite from the body.

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It was concluded that cattle are not an important part of maintaining the life-cycle of E granulosus in Queensland north of the Tropic of Capricorn. Within the endemic zone, which is almost all to the east of the Great Dividing Range, the local pattern of bovine echinococcosis is most likely to be determined by the presence or absence of small species of wallaby such as M dorsalis, M parryi and M rufogriseus.

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Movement of transmigrants and livestock from western Indonesia to southeastern areas of Irian Jaya near the border with Papua New Guinea may pose a risk of introducing

The midbody regions of female worms of six Onchocerca species (O. flexuosa, O. tarsicola, O. lienalis, O. gutturosa, O. armillata, O. gibsoni) were studied by transmission electron microscopy. The cuticular layering was rather similar in all species with the ridges built up by the cortical layers and the inner cuticular striations by the median or basal layers. Differences in the epicuticular morphology were considerable. O. flexuosa and O. lienalis had a thin epicuticle without protuberances, the epicuticle of O. armillata carried small knobs, and O. tarsicola, O. gutturosa, and O. gibsoni had a thick trilaminar epicuticle with long protuberances. Extreme hypertrophy of hypodermis and reductions of somatic musculature were observed in O. flexuosa and O. gibsoni. Less extended thickenings of the hypodermis were observed in the other species. No degenerative alterations were found in the muscle cells of O. gutturosa and O. lienalis. The intestinal lumen of most of the species was in a central position, but in O. tarsicola and O. gibsoni the lumen was reduced to small clefts between the intestinal cells. In these species, numerous electron-dense, concentric granules were observed in the cytoplasm of the intestinal cells. The proportions of the various organs differed considerably from species to species, e.g., the uteri contained the embryos filed one behind the other in O. tarsicola, whereas 50 or more embryos were found beside one another in cross-sections of the uterus of O. gibsoni. The comparative study showed that O. gibsoni and O. volvulus have many derived morphological characteristics in common and that in the other species more primitive stages of development of these morphological marks can be observed.

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