<span style="font-family: arial,helvetica;">Sixteen experimental burn plot replicates, in groups of four, in four landscape zones of the Kruger National Park, South Africa, and from which wildlife are not excluded, have been subjected to fixed, regular burning regimens since 1954. In 1999, a study to determine the effect of burning on ixodid ticks questing for hosts from the vegetation of the plots was initiated, and six sub-plots, with identical histories, within each of two of the burn plot replicates in <em>Combretum collinum / Combretum zeyheyri</em> woodland on granite, were selected. With few exceptions these 12 sub-plots, as well as unburned vegetation adjacent to each of the replicates, were sampled for ticks at monthly intervals for a period of 39 months by dragging with flannel strips. The existing regimen of burning during August or during October on individual sub-plots was continued during this time. A total of 14 tick species was recovered from the plots of which nine could be considered major species. Sufficient numbers for statistical analysis of only eight species were, however, collected. Burning appeared to have little short-term effect on the number of ticks recovered. In the longer term, the response varied from no change, an increase, or a decrease in the numbers of ticks collected each year after burning. Tick species, life cycle, seasonality, questing strategy, host preference and host utilization of the habitat were important determinants of the effect of burning.</span>

<span style="font-family: arial,helvetica;">During the period between January 1999 and December 2000, the distribution and seasonal patterns of <em>Schistosoma mattheei</em> infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe were determined through monthly coprological examination. Faecal samples of cattle were collected from 12 and nine dipping sites in the highveld and lowveld communal grazing areas, respectively. Patterns of distribution and seasonal fluctuations of the intermediate host-snail populations and the climatic factors influencing the distribution were also determined at monthly intervals from November 1998 to October 2000, a period of 24 months, in six dams and six streams in the highveld and nine dams in the lowveld communal grazing areas. Monthly, each site was sampled for relative snail density, the vegetation cover and type, and physical and chemical properties of the water. Mean monthly rainfall and temperature were recorded. Snails collected at the same time were individually examined for shedding of cercariae of <em>S. mattheei</em> and <em>Schistosoma haematobium</em>. A total of 16 264 (5 418 calves, 5 461 weaners and 5 385 adults) faecal samples were collected during the entire period of study and 734 (4.5 %) were positive for <em>S. mattheei</em> eggs. Significantly higher prevalences were found in the highveld compared to the lowveld (<em>P</em> &lt; 0.001), calves compared to adult cattle (<em>P</em> &lt; 0.01) and the wet season compared to the dry season (<em>P</em> &lt; 0.01). Faecal egg output peaked from October/ November to March / April for both years of the study. <em>Bulinus globosus</em>, the snail intermediate host of <em>S. mattheei</em> was recorded from the study sites with the highveld having a significantly higher abundance of the snails than the lowveld (<em>P</em> &lt; 0.01). Monthly densities of <em>B. globosus</em> did not show a clearcut pattern although there were peaks between March / May and September / November. The mean num ber of snails collected was positively correlated with the water plants <em>Nymphaea caerulea</em> and <em>Typha</em> species. Overall, 2.5 % of <em>B. globosus</em> were shedding <em>Schistosoma</em> cercariae. In the highveld, 2.8 % of <em>B. globosus</em> were infected with schistosome cercariae and 1.5 % in the lowveld, with the figures at individual sites ranging from 0-18.8 % in the highveld and from 0-4.5 % in the lowveld. The cercariae recorded here were a mixture of <em>S. mattheei</em> and <em>S. haematobium</em> since they share the same intermediate host. The transmission of <em>Schistosoma</em> cercariae exhibited a marked seasonal pattern, being more intensive during the hot, dry season (September / November).</span>

<span style="font-family: arial,helvetica;">The ultrastructure of the follicular wall in primordial, previtellogenic and vitellogenic follicles of the sexually immature ostrich is described in the present study. The follicular wall consists of a zona radiata, granulosa cell layer, basal lamina and thecal layer. Cytoplasmic processes from the plasma membranes of the granulosa cell layer and the ovocyte form the zona radiata in previtellogenic and vitellogenic follicles. The granulosa cell layer transforms from simple cuboidal epithelium in primordial follicles to simple columnar or pseudostratified columnar epithelium in previtellogenic and vitellogenic follicles. Transosomes were observed along the apical and lateral plasma membranes of granulosa cells. The thecal layer in previtellogenic and vitellogenic follicles consists of interna and externa components. The fibroblasts in the theca externa contain microfilaments, which are thought to be actin filaments. <br />The study revealed ultrastructural features, which are associated with the transportation of yolk precursors and nutrients into the ovoplasm. In addition, the study indicates that, although the cells in the theca externa contain microfilaments, they do not possess the ultrastructural characteristics of smooth muscle cells.</span>

<span style="font-family: arial,helvetica;">A total of 586 reptiles, belonging to 35 species and five subspecies, were examined in surveys aimed at determining the species spectrum and geographic distribution of ticks that infest them. Of these reptiles 509 were tortoises, 28 monitor or other lizards, and 49 snakes. Nine ixodid tick species, of which seven belonged to the genus <em>Amblyomma</em>, and one argasid tick, <em>Ornithodoros compactus</em> were recovered. Seven of the ten tick species are parasites of reptiles. Amongst these seven species <em>Amblyomma marmoreum</em> was most prevalent and numerous on leopard tortoises, <em>Geochelone pardalis</em>; <em>Amblyomma nuttalli</em> was present only on Bell's hinged tortoises, <em>Kinixys belliana</em>; and most <em>Amblyomma sylvaticum</em> were collected from angulate tortoises, <em>Chersina angulata. Amblyomma exornatum</em> (formerly <em>Aponomma exornatum</em>) was only recovered from monitor lizards, <em>Varanus spp.</em>; most <em>Amblyomma latum</em> (formerly <em>Aponomma latum</em>) were from snakes; and a single nymph of <em>Amblyomma transversale</em> (formerly <em>Aponomma transversale</em>) was collected from a southern African python, <em>Python natalensis</em>. All 30 Namaqualand speckled padloper tortoises, <em>Homopus signatus signatus</em>, examined were infested with <em>O. compactus</em>. <br />The seasonal occurrence of <em>A. sylvaticum</em> and the geographic distribution of this tick and of <em>A. marmoreum, A. nuttalli, A. exornatum, A. latum</em> and <em>O. compactus</em> are illustrated.</span>

<span style="font-family: arial,helvetica;">During surveys on the tick burdens of various wildlife species in South Africa, nine small antelopes became available for study. Six of these were steenbok, <em>Raphicerus campestris</em> and three sunis, <em>Neotragus moschatus</em>, and their tick burdens are recorded here. The steenbok were examined in three nature reserves and harboured nine tick species. The sunis were examined in a fourth reserve and were infested with eight species. The steenbok and sunis were generally infested with the immature stages of the same tick species that infest larger animals in the same geographic regions. In addition the sunis harboured <em>Haemaphysalis parmata</em>, which in South Africa is present only in the eastern and north-eastern coastal and adjacent areas of KwaZulu-Natal Province. They were also infested with <em>Rhipicephalus kochi</em>, which in South Africa occurs only in the far north-east of the KwaZulu-Natal and Limpopo Provinces.</span>