Rhipicephalus aquatilis sp. nov. (Acari: Ixodidae), a new tick species parasitic mainly on the sitatunga, Tragelaphus spekei, in East and Central Africa

This tick, originally referred to as Rhipicephalus species Ill by Yeoman & Walker (1967), was first collected from a sitatunga, Tragelaphus spekei, and then occasionally from cattle, in Tanzania. Further collections, mostly from sitatunga, have since been seen from Uganda and Zambia. Descriptions of the adults of this species are given, together with information on their hosts and their distribution.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.National Institute of Allergy and Infectious Diseases. Onderstepoort Veterinary Institute.mn201

Rhipicephalus interventus sp. nov. (Acari: Ixodidae), a new tick species closely related to Rhipicephalus tricuspis Dönitz, 1906 and Rhipicephalus lunulatus Neumann, 1907, from East and Central Africa

Descriptions of the adults of this new species are given, together with information on its hosts and distribution. Previously it was referred to briefly by Walker, Keirans, Pegram & Clifford (1988), who noted that in many respects it is intermediate in appearance between R. tricuspis and R. lunulatus.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.National Institute of Allergy and Infectious Diseases. Onderstepoort Veterinary Institute.mn201

Epidemiological observations of Zimbabwean theileriosis: disease incidence and pathogenicity in susceptible cattle during Rhipicephalus appendiculatus nymphal and adult seasonal activity

Fifty-nine Hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of Theileria parva under field conditions in Zimbabwe. They were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of Rhipicephalus appendiculatus nymphal and adult activity. All tracer cattle were herded together with the farm cattle but were not dipped. The nymphal tick counts were high on two of the farms (up to 2000 per animal) but were very low on the third farm (less than ten per animal). On the three farms, 19 out of 24 (76%) tracers had patent Theileria schizonts. There was a range of clinical manifestations of theileriosis with acute and fatal infections occurring on one farm. The adult R. appendiculatus infestations during the wet season numbered 120-800 per animal on the three farms. The disease transmitted by the adults was very pathogenic on the three farms; 30 out of 35 (86%) had severe theileriosis infections. Cattle, which survived the nymphal diseases challenge, showed various degrees of immunity to subsequent T. parva challenge transmitted by adult ticks. Therefore, 13 out of 18 (72%) of these cattle had a second disease episode and the case fatality rate on the three farms was 46%. The factors which determined the epidemiological status of Theileria challenge on the farms, such as the farming systems and presence of wild animals, are discussed.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Food and Agriculture Organization (FAO) of the United Nations. DANIDA. Government of Zimbabwe.mn201

Biosystematic studies on the genus Rhipicephalus The R. sanguineus and R. simus groups (Ixodoidea, Ixodidae)

SIGLEAvailable from British Library Document Supply Centre- DSC:DX79753 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Effects of immunisation against Theileria parva on beef cattle productivity and economics of control options

Over 500 cattle of all age groups on 2 farms in Zimbabwe were immunised against theileriosis using the "infection and treatment" method and disease prevalence and their productivity assessed during a period of 18 months. The immunising stock, Theileria parva (Boleni) was isolated in Zimbabwe. None of the immunised cattle suffered from theileriosis upon natural exposure whereas 22 unimmunised cattle died of theileriosis and a further 48 required treatment for theileriosis. In the first year, some immunised cattle were maintained with minimal threshold dipping (once or twice during the rainy season). During periods of very high tick challenge of 100 to 1,000 Rhipicephalus appendiculatus per animal from January to March, a transient decrease in liveweight gain was observed particularly in cows. However, by the end of the period of observation, the weights had recovered so that intensively dipped and immunised and threshold or strategically dipped groups of cattle showed no significant differences. From the results it w as estimated that each engorging female R. appendiculatus caused a temporary depression in weight gain of 8 grams. In young stock the weight loss was excerbated by the presence of screw worm (Chrysomya bezziana) infestation. It was then possible to define an economically attrative integrated tick and theileriosis control strategy based on these findings, whereby immunised cattle were dipped 6 times between mid-December and mid-March. In this regimen, no weight loss occurred and no cases of screw worm were observed. For each of 3 herd sizes of 250.000 and 1,000 cattle, comparisons were made of the costs of 4 different control options: 1. Intensive dipping (40 times/year). 2. Intensive pour-on acaricide treatments (18 times/year). 3. Theileria immunisation with strategic dipping (6 times/year). 4. Theileria immunisation with pour-on treatment (4 times/year). It is concluded from these studies that, on farms where theileriosis is a serious problem, immunisation coupled with a strategic dipping programme is economically very attractive. In the year in which immunisation is carried out, costs will be higher than for intensive dipping, but from the second year on, the costs are decreased to approximately 50 percent of those for intensive dipping