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Adult ixodid ticks were collected at 2-weekly intervals for a period of 23 consecutive months from 15 to 20 Angora goats on a farm in the south western Orange Free State. A total of 6 ixodid tick species were recovered. Rhipicephalus punctatus was the most abundant and prevalent tick. It was present from spring to late summer. Ixodes rubicundus was the next most abundant tick and was present mainly from March or April to July with peak numbers present in April or May. The onset of this tick's activity appeared to be stimulated by low atmospheric temperatures.

Sixteen species of ixodid ticks were collected over varying periods of time from 6 species of ground-frequenting birds and 15 species of small and large mammals in the Mountain Zebra National Park, Karoo, Cape Province. Margaropus winthemi followed by Rhipicephalus glabroscutatum and Rhipicephalus evertsi evertsi were the most abundant species. The host preferences of 14 tick species and the seasonal abundances of 13 species were determined. Small numbers of immature stages of only a few tick species were generally recovered from ground-frequenting birds, mice and rats. Amongst the slightly larger animals the smallest number of ticks and species were recovered from springhares and the largest numbers from scrub hares. Amongst the larger mammals, very few ticks were harboured by springbuck and black wildebeest, while heavy infestations of several species were encountered on Cape mountain zebras and eland.

The scapulocostal syndrome, a hitherto insufficiently understood condition, was clinically studied in 201 cases. The main findings were: (i) pain was the presenting symptom in all cases and was mainly cervicobrachial (90%); (ii) the syndrome is a definable entity within the wide spectrum of fibromyalgia (fibrositis); (iii) the pain originates mainly from an enthesopathy of the serratus posterior superior muscle; and (iv) physical degeneration was present in 76.5% of patients. Conservative treatment, successful in 95.9% of cases, consisted of an intralesional injection of a steroid-analgesic-mixture of 1 ml Celestone-Soluspan (Scherag) plus 1.8 ml Xylotox E80A (Astra), and physical rehabilitation. It was deducted that the dyskinesia was mainly due to an overload of the scapulocostal articulation, forcing the rib cage down to exert a stretching force on the serratus posterior superior muscle. The operation of 'serratotomy' (severing the serratus posterior superior muscle) was performed with excellent results in 6 patients in whom conservative treatment failed, and is described here for the first time.

A number of young Friesian oxen were slaughtered (one at a time) for parasite recovery for 12 consecutive months, from April 1987 to March 1988, on a farm in the Fauresmith district of the south western Orange Free State. A total of 5 ixodid and one argasid tick species, 2 lice species, plus one nematode species and one cestode species, were recovered. Peak numbers of adult Hyalomma marginatum rufipes were present from November 1987 to February 1988, while the largest numbers of Hyalomma truncatum were recovered during September 1987 and from November 1987 to January 1988. Adult Ixodes rubicundus were recovered only during April and June 1987. Adult ticks of a Rhipicephalus sp. near R. punctatus were present during April and from September to November 1987 and in January 1988. No pattern of seasonal abundance was evident for the other tick species, the lice or the helminths.

The ratio of variance to mean (s2/means) of numbers of Ixodes rubicundus (males and females) per sheep was used as a measure of the dispersion pattern of this tick within a naturally infested population of sheep. Sheep were divided into two groups, one with previous contact with I. rubicundus and the other with no previous contact. Samples of 10 sheep from each group were searched for ticks on a weekly basis for 19 weeks during the winter of 1986. In each group, both male and female ticks had an s2/means ratio greater than 1 for the majority of observation periods indicating an aggregated dispersion pattern. The degree of aggregation was greater with increasing density of the ticks. The implications of these results are discussed both in relation to sampling procedures and potential control strategies.

Five or 6 rock dassies (Procavia capensis) were shot at monthly intervals for 13 consecutive months in the Mountain Zebra National Park and processed for arthropod parasite recovery. Ten species of ixodid ticks and 2 flea species were recovered. The seasonal prevalence of the rock dassie ticks, Haemaphysalis hyracophila and Rhipicephalus distinctus, and of the immature stages of Rhipicephalus arnoldi, a tick that usually infests the red rock rabbit (Pronolagus rupestris), was determined. Only 10 of the approximately 10 000 ticks recovered from the rock dassies belonged to species that may infest domestic livestock.

A variety of mammal and bird species in the Mountain Zebra National Park, eastern Cape Province, were examined for Ixodes rubicundus. In addition, caracal (Felis caracal) from the park and its vicinity as well as from the Graaff-Reinet region of the Karoo were examined. Amongst the animals collected, the red rock rabbit (Pronolagus rupestris) was a preferred host of the immature stages of the tick. Caracal were moderately good hosts of these stages and, with mountain reedbuck (Redunca fulvorufula) and eland (Taurotragus oryx), are the preferred hosts of adult ticks.

With the exception of October, when no collections were made, adult ticks were collected at weekly intervals from February 1986 to January 1987 from 20 randomly selected sheep out of a flock of 60. Ixodes rubicundus was the most abundant tick and was present from April to September with a peak during May. Hyalomma marginatum rufipes was the next most numerous tick. It was recovered throughout the year with peak burdens being recorded from November to April. Small numbers of a Rhipicephalus sp. (near R. pravus) were also collected. These exhibited a major peak during February and a minor peak during August. A dipping programme to prevent the paralysis caused by I. rubicundus and the Rhipicephalus sp. (near R. pravus) is suggested.

Male Ixodes rubicundus were found in copula with attached females in 59% of individuals. The number of males attaching to the female integument or to the the host negligible. In laboratory experiments, males enclosed with females in a small vial had significantly longer life spans than solitary males. Paired males were found to be in copula on 20-34% of observations. Solitary males lost weight while paired males gained weight over a 2-day period. However, the specific energy content of the 2 groups remained constant.

Paralysis of Angora goat kids caused by adult ticks, which most probably belong to an undescribed species of the Rhipicephalus pravus group, is described. Confirmed cases of paralysis occurred in the south-western Orange Free State between the second half of September and the first half of November as well as during the first half of February. The mean female tick burdens (mean = 21.4) of paralysed Angora kids were significantly higher than those of healthy kids (mean = 4.4). The predilection attachment site of the adult ticks was the ears of the goats. The elephant shrew Elephantulus myurus is a preferred host of the immature stages whereas the scrub hare Lepus saxatilis serves as an important host for the adult ticks.

The weights of feeding female Ixodes rubicundus attaching to sheep was studied in a natural focus of Karoo paralysis. The studies showed fewer females in the middle weight ranges and more in the heavier and lighter categories than would be expected if the distribution was normal. Weights were also strongly skewed towards the lighter females between 0 and 400 mg. No differences in the pattern of attachment weights occurred over the four experimental groups used, suggesting that previous contact of sheep with I. rubicundus had no effect on the ability of the tick to engorge.

The epidemiology of Karoo paralysis, induced by the tick Ixodes rubicundus, was investigated in a paralysis-enzootic area of the southwestern Orange Free State, Republic of South Africa. Sheep became paralysed during the last week of April and the first week of May during the 1985 and 1986 seasons, respectively. Paralysis cases were recorded up until July, but most paralysis cases occurred during the first week of May with a second but smaller peak occurring during June. Tick numbers on paralysed sheep closely followed peak periods in paralysis. A total of 65 and 50% of the naive sheep became paralysed during the 1985 and 1986 seasons, respectively. The seasonal pattern of tick infestation by female I. rubicundus was similar on both previously exposed and on naive sheep. The results of this study indicate that a certain number of ticks per kilogram host body mass is required before symptoms of paresis of paralysis are observed. In general the tick burden per kilogram host mass was significantly greater in paralysed compared to non-paralysed sheep. The range in the number of ticks per kilogram host mass may, however, overlap between non-paralysed and paralysed groups. Previously exposed or previously paralysed sheep are less susceptible to paralysis in the following year. Differences in susceptibility between individual sheep seems likely.