Search

Introduction: The sexual behaviour and development of children with autism spectrum disorders (ASDs) have been mostly overlooked in research and practice. This study aimed to determine the association between certain clinical and demographic factors found in a sample of children with ASDs, and their reported sexual behaviour (RSB)., Methods: The study was conducted at a school in Gauteng, South Africa, for learners with ASDs. Two questionnaires completed by caregivers/parents enquired about family stability, clinical profile and RSB (if any) in their child. RSB was analysed via three domains: self-care, socio-sexual skills and actual RSB, with additional information from school records., Results: Of the 107 questionnaires distributed, only 31 parents responded and 24 agreed to participate. The 24 (100%) children included 10 pubertal and 14 pre-pubertal children, of which 18 ( n = 18) had more stable primary caregiver statuses as well as more stable socioeconomic and family environments. Two of the 14 pre-pubertal children had abnormal self-care, whereas none of the 10 pubertal children had any abnormal self-care. Eight of the 18 children from more stable environments displayed abnormal sexual behaviours. Of the 6 children from less stable environments, two displayed more abnormal socio-sexual skills, whereas 9 of the 18 children from more stable environments displayed more abnormal sexual behaviour. In contrast with the postulated hypothesis that children from less stable socioeconomic and family environments would exhibit more abnormal sexual behaviours, this study did not find any evidence of such a relationship or association., Conclusion: ASDs are characterised by deficits in communication and social skills. These may lead to an affected individual struggling to develop appropriate sexual behaviour. If specific risk factors that contribute to the development of abnormal sexual behaviour can be identified, one can try to modify/prevent these where some degree of prevention or alleviation may be possible., Competing Interests: The authors declare that they have no financial or personal relationships which may have inappropriately influenced them in writing this article.

The objective of this study was to determine the species spectrum of ixodid ticks infesting birds in Free State Province, South Africa. To this end a large number of birds belonging to several species were examined for ticks and a total of 180 birds belonging to 39 species at 17 localities were infested, and ticks belonging to eight species were recovered. The immature stages of only two, namely Amblyomma marmoreum and Hyalomma marginatum rufipes, were sufficiently prevalent and numerous to safely assume that they regularly use birds as hosts. Helmeted guineafowls, Numida meleagris, were the most heavily infested and one harboured a total of 319 larvae and four nymphs. Amongst the other species an eastern clapper lark, Mirafra fasciolata, was infested with 69 larvae and a nymph, but no other bird harboured more than 40 ticks. The larvae and nymphs of H. m. rufipes were most numerous on birds from April to August.

Two hundred and seventy-three elephant shrews, consisting of 193 Elephantulus myurus, 67 Elephantulus edwardii and 13 animals belonging to other species, were examined for ixodid ticks at 18 localities in South Africa and Namibia. The immature stages of Ixodes rubicundus, Rhipicentor nuttalli, Rhipicephalus warburtoni and a Rhipicephalus pravus-like tick were the most numerous of the 18 tick species recovered. Substantial numbers of immature Rhipicephalus arnoldi, Rhipicephalus distinctus and Rhipicephalus exophthalmos were also collected from elephant shrews at particular localities. Larvae of I. rubicundus were most numerous on E. myurus in Free State Province from April to July and nymphs from June to October. Larvae of R. nuttalli were most numerous on these animals during April, May, August and September, and nymphs in February and from April to August. The immature stages of R. warburtoni were collected from E. myurus only in Free State Province, and larvae were generally most numerous from December to August and nymphs from April to October.

Two hundred and twenty-five small mammals belonging to 16 species were examined for ticks in Free State, Mpumalanga and Limpopo Provinces, South Africa, and 18 ixodid tick species, of which two could only be identified to genus level, were recovered. Scrub hares, Lepus saxatilis, and Cape hares, Lepus capensis, harboured the largest number of tick species. In Free State Province Namaqua rock mice, Aethomys namaquensis, and four-striped grass mice, Rhabdomys pumilio, were good hosts of the immature stages of Haemaphysalis leachi and Rhipicephalus gertrudae, while in Mpumalanga and Limpopo Provinces red veld rats, Aethomys chrysophilus, Namaqua rock mice and Natal multimammate mice, Mastomys natalensis were good hosts of H. leachi and Rhipicephalus simus. Haemaphysalis leachi was the only tick recovered from animals in all three provinces.

The objective of this study was to determine certain aspects of the biology of Rhipicephalus (Boophilus) decoloratus larvae under laboratory and field conditions. Larvae allowed 48 h to select a vertical questing substrate preferred 90 cm rods in length to those of 60 or 30 cm, while in a separate experiment migration from rods 5 cm or 25 cm in length to rods 45 cm in length continued between 48 h and 72 h after larval release. Hatching of the larval progeny of engorged female ticks exposed to ambient field temperatures during the period June to August, occurred synchronously during the third or fourth week of November. With a single exception, larvae that hatched during November and between April and July survived for 38 days or longer, while those that hatched from December to March survived for 31 days or less. Questing larvae were present on vegetation throughout the year, with most being recovered during January and February. Parasitic larvae were present on cattle from October to May with most being collected during January and February.

Engorged female Haemaphysalis leachi and Rhipicephalus sanguineus as well as their eggs, flat and engorged larvae and nymphs were incubated at combinations of five temperatures and three relative humidities. Mean pre-oviposition periods for H. leachi varied between 4.3 days and 12.1 days and for R. sanguineus between 4.8 days and 21.0 days. Haemaphysalis leachi converted up to 65.7% of their body mass into eggs and produced up to 16.3 eggs/mg body mass, with 4801 eggs the maximum number deposited by a single female. Peak egg production of 520 eggs/day was recorded 3 days after the commencement of oviposition. Rhipicephalus sanguineus converted up to 68.1% of their body mass into eggs and produced up to 17.2 eggs/mg body mass, with a maximum of 3,232 eggs, and peak egg production of 400 eggs/day 4 days after the commencement of oviposition. Mean incubation periods for eggs of H. leachi varied between 15.5 days and 66.7 days, and for R. sanguineus between 19.0 days and 72.0 days. Mean pre-moult periods for engorged larvae and nymphs of H. leachi varied between 14.0 days and 192.0 days, and 13.0 days and 41.0 days respectively, and for R. sanguineus between 9.5 days and 36.5 days, and 15.0 days and 44.5 days respectively. Allowing 7 days for female engorgement and 7 days for hardening of the exoskeletons and mouthparts of each of the three parasitic stages before they attach to a host, the life cycle of H. leachi would require 97-190 days and that of R. sanguineus 99-236 days to complete at the various regimes of temperature and relative humidity. The greatest proportion of H. leachi larvae engorging on mice detached between 18:00 and 19:00 on the first day of detachment and between 06:00 and 08:00 in the morning and 14:00 and 18:00 in the afternoon of the following day, while the greatest proportion of nymphs engorging on dogs detached around 19:00 on the first day of detachment and between 13:00 and 17:00 on the following day. The greatest proportion of R. sanguineus larvae engorging on dogs detached between 11:00 and 21:00 on the second day of detachment, and the greatest proportion of nymphs detached between 03:00 and 5:00 on the second and third days of detachment.

Fleas collected from the elephant shrews Elephantulus edwardii (A. Smith, 1839) in the Western Cape Province, Elephantulus myurus Thomas & Schwann, 1906 in Free State Province, and an Elephantulus of undetermined species in the Eastern Cape Province, South Africa are recorded in this paper. Five flea species were recovered of which Demeillonia granti (Rothschild, 1904) was the most numerous and prevalent. It was followed by Macroscelidopsylla albertyni De Meillon & Marcus, 1958, collected only from E. edwardii. Both this elephant shrew and the locality are new records for M. albertyni. Chiastopsylla octavii (Rothschild, 1904), Listropsylla agrippinae (Rothschild, 1904), and a female flea of the Ctenocephalides felis group were accidental infestations. The sex ratio of D. granti was 0.86 on both male and female elephant shrews, while that of M. albertyni on E. edwardii was 0.83.

Five Merino and five Dorper sheep were artificially infested with the sheep scab mite Psoroptes ovis and the effect of infestation on their haematology, serum protein levels and live mass recorded for a period of 14 weeks. The reaction of the Merino sheep to infestation was more severe than that of the Dorper sheep. Haematological values fluctuated within the normal range during the assessment period. The mean haemoglobin concentration of the Merino sheep declined until antiparastic treatment was administered 10 weeks after infestation, after which it gradually increased. The lymphocyte counts of both breeds of sheep declined from 2 weeks to 10 weeks post-infestation, but increased after treatment, while the highest eosinophil counts were recorded in the Merino sheep at the height of the acute disease 8-10 weeks post-infestation. Serum albumin values for both breeds and serum globulin values for the Merino sheep were higher than normal during the entire 14-week observation period. A decrease in serum albumin and an increase in serum globulin concentration occurred at the height of infestation in both breeds. The mean live mass of a second group of five infested Merino sheep decreased by 6.4 kg over a 16-week period compared to a gain of 4.56 kg for five infested Dorper sheep.

These studies were conducted to investigate the possible role of certain aspects of the on-host ecology and off-host survival of the sheep scab mite, Psoroptes ovis, in the dissemination of infestation. All developmental stages of the mite occurred in the fleece both proximally or distal to the skin of infested Merino and Dorper sheep. A larger proportion of mites was present in the fleece of Dorper sheep distal to the skin in the late afternoon and early morning than at other times during the day. Immature and adult mites readily transferred to tufts of wool or hair placed on infested sheep of both breeds. No mites could be found on wool or hair rubbed off onto tree trunks or branches or other structures in enclosures housing heavily infested sheep, nor could any mites be collected from the soil of these enclosures, whereas more than 80% of mites artificially seeded onto soil samples were recovered. The longest mean off-host survival times for larvae, nymphs, and male and ovigerous female mites were recorded at 10 degrees C, and were 9.25 days (RH = 90%), 15 days (RH = 33% and 75%), 10.5 days (RH = 75% and 90%) and 11.25 days (RH = 90%) respectively. Under natural climatic conditions ovigerous females in glass vials containing Merino wool survived for 17 days compared to 15 days for females in vials without wool; this difference was, however, not significant. The mean off-host pre-hatch period for eggs varied between 5.9 days (T = 25 degrees C and RH = 33%) and 22.1 days (T = 10 degrees C and RH = 75%), while the longest time individual eggs took to hatch at the latter temperature and RH was 31 days.

There are only two species worldwide within the genus Rhipicentor, namely Rhipicentor bicornis and Rhipicentor nuttalli and both occur only in Africa. Rhipicentor nuttali has a widespread distribution in South Africa and the present investigation was initiated to elucidate its host preference, seasonality and life cycle. Rock elephant shrews, Elephantulus myurus were examined for ticks at four localities in the Free State Province, one in Gauteng Province and two in Limpopo Province, South Africa. Cape elephant shrews, Elephantulus edwardii were examined at two places in the Western Cape Province, and a single specimen of the bushveld elephant shrew, Elephantulus intufi was examined in central Namibia. Small mammals of other species were also examined at two of these localities. The majority of E. myurus at two sites in the Free State, at the locality in Gauteng and both sites in Limpopo Province were infested with larvae and/or nymphs of R. nuttalli, while the single E. edwardii examined at one site in the Western Cape Province and the single E. intufi examined in Namibia were infested with nymphs of this tick. Not one of the other small animals was infested. Although larvae and nymphs of R. nuttalli were present on E. myurus throughout the year, the former were generally most numerous during the period March to September, and the latter during May to October. The preferred hosts of the adults are domestic dogs, leopards, Panthera pardus and South African hedgehogs, Atelerix frontalis. Adult females engorged on Atelerix frontalis in 16-32 days and, after a preoviposition period of 2-4 days, produced approximately 170,00 eggs during the following 60-70 days. The average incubation period of the eggs was 59 days. Larvae engorged on E. myurus in 4-10 days and moulted to nymphs 12-20 days later. Nymphs required 11-15 days to engorge on E. myurus and moulted to adults 32-47 days later. Allowing 14 days for the exoskeletons and mouthparts of each of the three parasitic stages to harden before they can attach to a host, the life cycle took approximately 214 days to complete in the laboratory. The length of this period, considered in conjunction with the times of maximum seasonal occurrence of the immature stages, indicates that the life cycle probably takes a year to complete in the field.

A field study (February 2000 to August 2001) was conducted on communal and commercial farms in the Eastern Cape and North-West Provinces of South Africa to detect the levels of tick resistance to commonly used acaricides. The larvae obtained from engorged females of the one-host tick Boophilus decoloratus, the two-host tick Rhipicepalus evertsi evertsi and the three-host ticks Amblyomma hebraeum and Rhipicephalus appendiculatus were tested against various concentrations of amitraz, chlorfenvinphos and cypermethrin using the Shaw Larval Immersion Test method. Ticks from the communal farms showed higher levels of resistance to cypermethrin and some resistance to chlorfenvinphos whilst no resistance was detected against amitraz. However, ticks from commercial farms were equally resistant to amitraz, chlorfenvinphos and cypermethrin. The B. decoloratus populations tested were considerably more resistant to all the acaricides tested than the R. evertsi evertsi, A. hebraeum and R. appendiculatus populations. This supports the hypothesis that single-host ticks develop resistance faster than multi-host ticks. This trend was recorded on most of the farms where single- and multi-host ticks co-existed. It was concluded that the use of acaricides at high frequencies and high concentrations was one of the main causes of tick resistance in the study areas. Possible factors which caused the resistance problems are discussed and acaricide management strategies recommended.

Several surveys of ticks infesting dogs belonging to owners in resource-limited and more affluent communities have been conducted in South Africa, but no such investigation has been carried out in the Free State Province of this country. The present study was initiated to meet this shortcoming. Ticks were collected from dogs at six localities in, and to the east of the city of Bloemfontein in the central region of the province. Three of these localities could be classed as resource-limited and two as affluent, while the sixth locality was an animal shelter serving all members of the public. Adult ticks belonging to nine ixodid tick species were collected, of which Rhipicephalus sanguineus was the most numerous. Significantly more R. sanguineus was collected from dogs at resource-limited than at more affluent localities. The greatest proportions of these ticks attached to the backs and necks of the dogs, with the proportions being larger in long-haired than in short-haired dogs. Most R. sanguineus were collected during the warmer months particularly from January to April. The greatest proportions of Haemaphysalis leachi, the next most numerous species, were also collected from the backs and the necks of the dogs. Most of these were present during the period September to November.

Ixodid ticks were collected from 104 wild carnivores belonging to 23 species in various nature reserves and on several farms in all nine provinces of South Africa. Seven feral cats in a nature reserve were also examined. Twenty-four tick species belonging to seven genera were recovered and identified. Amongst these ticks we consider the adults of Haemaphysalis leachi, Haemaphysalis spinulosa, Haemaphysalis zumpti, Ixodes rubicundus, Rhipicentor nuttalli, Rhipicephalus simus and Rhipicephalus turanicus to be true parasites of wild carnivores. Although numerous adult Rhipicephalus appendiculatus and Rhipicephalus zambeziensis were collected from some lions these were either sick or old animals. The immature stages of seven species regularly utilized wild carnivores as hosts on an opportunistic basis.

This questionnaire survey was conducted amongst 200 farmers in the resource-poor, urban and per-urban environments of Botshabelo and Thaba Nchu towns in the Free State Province of South Africa. The questionnaire was divided into seven sections, namely demography, livestock, cattle, parasites, parasite control, livestock diseases and problems experienced. A total of 87.5% of the livestock owners were not employed (unemployed or pensioner). Cattle constituted more than 50% of the live-stock units owned in the area and farmers owned an average of 9.33 +/- 0.812 head of cattle. A total of 193 (96.5%) of the farmers indicated that milk was the most important product from their cattle. Only 26% of them slaughtered their own cattle for meat consumption. Eighty-eight percent of them indicated that external parasites on their livestock presented a problem, but only 72.9% of farmers implemented any tick control measures. Less than half (45.5%) of the farmers who attempted to control ticks used commercial acaricides. The remainder used various other methods, including the application of used engine oil and household detergents. Amongst the clinical diseases observed in their cattle, dry gallsickness was mentioned most often (20%). This figure, however, is believed to be inaccurate because dry gallsickness may be a clinical manifestation of some of the other diseases mentioned by the farmers, such as anaplasmosis, foreign body obstruction of the gastro-intestinal tract by plastic bags, pneumonia and mastitis. Animal husbandry problems experienced by the farmers included pollution (i.e. ingestion of plastic bags and string by their livestock), availability of water and theft.

Twelve Bonsmara tracer calves (aged 6-12 months) were used to monitor helminth infections in the communal farming system of Botshabelo in the Free State. One calve was slaughtered each month from December 1995 to November 1996 and processed for helminth recovery. All the calves harboured worms, but the numbers were always low. The order of prevalence of the major parasites was Trichostrongylus axei, Haemonchus placei, Cooperia punctata and Cooperia pectinata.

The study was conducted in a peri-urban agricultural system at Botshabelo, a city in the south-eastern Free State. A questionnaire survey revealed that 88.5% of cattle farmers in the area experienced problems related to ticks and tick-borne diseases. Because of the cost of commercial acaricides the Botshabelo farmers use alternative, cheaper methods of tick control, including the application of used engine oil. The specific aim of the study was to determine whether used engine oil can effectively control ticks on cattle. From March to August 1996 the tick burdens of ten control animals and six animals treated by their owner with used engine oil were compared. The total tick burdens for the 6 month period differed significantly between the two experimental groups. The efficacy of the used engine oil on the treated group varied between 15.1% and 64.8% with a mean of 38.1%. Although commercial acaricides can be more cost-effective, the application of used engine oil can be useful to reduce tick numbers on cattle during periods of peak abundance. Another advantage in that the use of the oil will not influence existing endemic stability of Anaplasma marginale and Babesia bigemina infections because of the residual tick burdens after treatment.

The objectives of this study were to determine the diversity, seasonal dynamics and abundance of ticks infesting cattle in urban, small-scale farming communities in and around Botshabelo and Thaba Nchu in the eastern Free State Province, South Africa. A total of ten cattle, ear-tagged for individual identification, were investigated monthly at each of five localities. Adult ticks were removed from the right hand side of each animal and placed in containers filled with 70% ethanol. They were subsequently identified and their numbers quantified. Immature Otobius megnini were counted but not removed. A total of 244,538 adult ticks of ten different species were collected over the 12-month study period. The tick species, in decreasing order of relative abundance, were: Boophilus decoloratus (87.26%), Rhipicephalus evertsi evertsi (6.86%), Hyalomma marginatum rufipes (2.42%), Otobius megnini (1.85%) Rhipicephalus follis (0.76%), Rhipicephalus gertrudae (0.54%), Rhipicephalus sp. (0.21%), Ixodes rubicundus (0.08%), Hyalomma truncatum (0.01%) and Margaropus winthemi (0.004%). The three most abundant species, namely B. decoloratus, R. evertsi evertsi and H. marginatum rufipes, occurred at all localities but with significant differences in abundance. M. winthemi ticks occurred only in the Thaba Nchu area and were not found at any of the there localities in Botshabelo. Significant differences in tick burdens between the six warm months (September to February) and the six cooler months (March to August) were found for most of the species recorded. Boophilus decoloratus occurred in significantly higher numbers in autumn (March to May) and winter (June to August) compared to spring (September to November) and summer (December to February), with 76.8% of the total B. decoloratus burden occurring during the cooler months.

Relative resistance levels of cattle against tick infestations in the communal grazing area of Botshabelo in the south-eastern Free State were determined. The objective was to establish whether differences in resistance can be exploited to contribute to tick control methods used by small-scale farmers in resource-poor environments. Ten cows (Bos taurus crosses) between the ages of 18 months and four years were used and tick counts were conducted once a month over a period of 12 months to compare their total tick burdens. Tick burdens of the various animals were compared mutually as well as with the mean tick burden of the group as a whole. Tick numbers varied throughout the year on all individuals but some animals consistently tended to have either higher or lower numbers than the mean of the group. Tick burdens on cattle classified as having a relatively low resistance to tick infestations increased eleven-fold from January to June 1996 compared to a six-fold increase on cattle categorized as belonging to the high resistance group. Twenty-eight percent of the cattle in the total study group carried 50% of the ticks collected (60,079). It is recommended that farmers in the region visually assess B. decoloratus burdens, the most abundant tick species, and sell or cull the most susceptible animals first in their normal program of utilization of the animals. This should eventually result in the direct improvement of the overall tick resistance of their cattle herds.

A seroepidemiological study was conducted on 151 cattle from the Botshabelo and Thaba Nchu areas in the central Free State Province of South Africa, two areas where small scale, peri-urban cattle farming is practised. An indirect fluorescent antibody test was used to test for Babesia bigemina and B. bovis antibodies. To test for Anaplasma marginale antibodies a competitive inhibition enzyme-linked immunosorbent assay method was used. There were no significant differences in serological test results between the cattle from Botshabelo and those from Thaba Nchu. The herd (two areas combined) had an average seroprevalence of 62.42% to B. bigemina, 19.47% to B. bovis and 98.60% to A. marginale. Based on the percentage of cattle that were seropositive to B. bigemina the immune status of cattle in the Botshabelo-Thaba Nchu area is approaching a situation of endemic stability. With reference to A. marginale, the high seroprevalence is indicative of a situation of endemic stability. The occurrence of B. bovis antibodies in the cattle is difficult to explain as Boophilus microplus ticks do not occur in the area in which the study was conducted.

The possible use of chickens as predators of livestock ticks was studied. Chickens were allowed to scavenge for 3 h among tick-infested cattle in a typical township backyard during the milking period. Boophilus decoloratus, Hyalomma marginatum rufipes, Rhipicephalus evertsi evertsi and Otobius megnini were recovered from the crops and gizzards at necropsy. The numbers of ticks ingested ranged from 0-128, with an average of 28.81 (+/- 8.42) per chicken. This study has confirmed that chickens are natural predators of livestock ticks and that chickens can be used as part of an integrated tick control plan in urban cattle-management systems in resource-poor communities in South Africa.

Karoo paralysis in South Africa is induced in livestock by feeding female Ixodes rubicundus ticks when infestation densities on hosts exceed certain critical levels. It has been shown previously that Angora goats are at a higher risk of being paralysed than Merino sheep, and such differences have been related to differences in feeding behaviour and spatial distribution of the two small-stock breeds. We hypothesized that differences in infestation densities with Karoo paralysis ticks would also occur between Merino and Dorper sheep breeds. A study was conducted under natural conditions in the south-western Free State, to compare infestation burdens of the two sheep breeds and also to investigate seasonal patterns and annual variations in variations in terms of rainfall and temperature. Ten animals of each breed ran free in an area with a known history of Karoo paralysis and were examined on an approximately fortnightly basis, from March 1992 to December 1995, to determine tick abundance. Differences between the two breeds were significant (P < 0.05) during 1992 and 1993, but not during 1994. During the first two years, peak abundance of ticks was reached earlier in Dorper than in Merino sheep, and it also reached higher levels in Dorper than in Merino sheep (mean = 17.9 and 7.3, respectively). In 1993, two Dorper, but no Merino sheep, were paralysed. Dorper sheep are clearly at a higher risk of being paralysed than are Merino sheep, and as such, they can serve as indicators of adult tick activity and hence of the time to commence prophylactic treatment. Differences between the two breeds are probably related to differences in grazing patterns. Marked variation in abundance and the time of onset of peak activity of I. rubicundus occurred over the years. Tick numbers were high in 1993 and 1995, but very low in 1992. In 1993, peak activity occurred earlier (April) than during the other years (June or July). These differences are related to differences in prevailing environmental conditions that influence tick activity in a complex manner. Heightened humidity and lower temperatures during the early stages of seasonal activity of the tick (April or May), normally result in peak abundance of ticks on hosts at that time.

Successful prophylaxis of paralysis, induced in small stock by feeding female Ixodes rubicundus, is dependent on the accurate determination of the commencement of seasonal activity by the tick. The commencement of this activity was recorded for 11 consecutive years on a farm in the south-western Free State, South Africa, and for shorter periods on other farms, some of these in regions with markedly colder climates. The colder the mean minimum atmospheric temperatures during the 2 months preceding the start to tick activity, the earlier it commenced. This could differ by 4 weeks from year to year on the same farm. In a region with a low effective temperature activity commenced between 3-8 weeks earlier than in a region with a higher effective temperature.

A study was conducted to compare the species of adult ixodid ticks on Friesian and Bonsmara cattle and their seasonal dynamics. Between five and ten animals of each breed were kept on natural False Upper Karoo vegetation, typical of the south-western Free State. Between May 1990 and October 1991, the animals were examined once or twice a month for the presence of adult ticks which were removed, counted and identified. Six species of ixodid ticks were recorded. The species composition on the two cattle breeds was remarkably similar. Ixodes rubicundus was dominant (55-57.7% of all ticks collected), followed by Hyalomma marginatum rufipes (28.9-31.5%) and Rhipicephalus punctatus *6.2-6.7%). Only small numbers of Hyalomma truncatum, Rhipicephalus evertsi evertsi and Rhipicephalus gertrudae were recorded. Almost twice as many ticks were collected from Friesian as from Bonsmara cattle. Ixodes rubicundus showed a typical winter-activity period. The other species were either active mostly during the warmer months, or their numbers were to low to determine any seasonal pattern. Apart from information on the diversity of ticks which infest cattle in the region, the study has also shown a greater resistance by Bonsmara cattle (a mixed Bos taurus/Bos indicus breed) to tick infestation. Bos indicus cattle can play an increasingly important role in integrated tick-management practices in southern Africa.

Hyalomma ticks were collected from Merino and black-headed Dorper sheep and their attachment preferences determined. The preferred site of attachment for Hyalomma marginatum rufipes on both Dorper and Merino sheep was the anogenital and inguinal areas (75-76%). On Dorper sheep, H. truncatum attached predominantly to the anogenital and inguinal areas (67.7%). On Merino sheep, most adults of this species attached to the feet (26%). Almost equal percentages also attached to the anogenital/inguinal and brisket areas (21.6 and 22.9%, respectively). These differences should be considered when pour-on acaricides are applied to different breeds of sheep.

An outbreak of lameness amongst Merino lambs, associated with the presence of Hyalomma ticks, was investigated on a farm in the south-western Free State, South Africa. The purpose was to follow the progress of the condition and to determine the extent of involvement of the two Hyalomma species which occur in the region. The flock of experimental sheep (n = 460) ranged free in natural veld under extensive farming conditions. During September and October 1993, adult ewes and lambs in this flock were examined at weekly intervals to determine tick identity, abundance and attachment-site preferences on lame and unaffected animals. Lameness occurred only among lambs, of which 68 were affected during the 8-week period. Hyalomma ticks tended to aggregate and mean numbers of ticks/aggregation were significantly higher on lame lambs (mean = 11.3) than on either the unaffected lambs (mean = 6.9) or the ewes (mean = 7.1). Most tick aggregations (72.4%) on the lame lambs occurred on the lower legs and feet, 34 out of 55 of these on the fetlocks or interdigital clefts. Hyalomma truncatum dominated (> 97%) on all animals examined. Only 15.8% of the Hyalomma marginatum rufipes recovered from the lame animals were attached to the legs. At two other localities at which H. marginatum rufipes was more abundant, or even dominant, few ticks attached to the lower legs or feet. Those that did were mostly H. truncatum (> 90%). Both H. marginatum rufipes and H. truncatum may attach to the same ventral and anogenital body regions, but H. truncatum has a tendency to attach also to the feet and lower legs. Although attachment of one or a few ticks in the axillar region or upper legs may cause lameness in sheep, the attachment of ticks to the interdigital clefts and fetlocks almost always causes lameness. The latter condition is more likely to occur in regions where H. truncatum dominates.

Detachment rhythms of immature Karoo paralysis ticks (Ixodes rubicundus) from their natural host, the rock elephant shrew (Elephantulus myurus), were investigated under laboratory and natural conditions. Larvae and nymphs detach mainly during the day. Peak detachment always occurred after the commencement of artificial as well as natural light cycles. The detachment of larvae appears to be more synchronous than that of nymphs, with a larger percentage of larvae detaching over a shorter period of time. The detachment rhythms of I. rubicundus are strongly correlated with the activity patterns of their hosts. This enhances not only the survival, but also the dispersion and host contact of subsequent stages.

Engorgement, mass at repletion and moulting success of immature Ixodes rubicundus after sequential infestations of their natural hosts, rock elephant shrews (Elephantulus myurus), were investigated under laboratory conditions. The reaction of E. myurus is characterized by inefficient or non-existent anti-tick immunity which enables immature I. rubicundus to attach and engorge successfully and ensures a high moulting success rate.

A suspended-net technique was used to capture blackflies attracted to and engorging on Dorper and Merino sheep on irrigated pastures. Two bait animals of each breed were restrained individually in wire-mesh enclosures located within four larger pens, each containing nine more animals of the same breed. Nets were suspended partly over the restrained animals and blackflies were collected at the end of 2-hour or longer periods. Mean numbers of blackflies captured in association with Merino (73.3/h) and Dorper sheep (89.1/h) did not differ significantly. Numbers of captured blackflies correlated (rho = 0.8361) with levels of irritation shown by sheep. Engorgement on Merinos was significantly (p = 0.009) higher than on Dorpers. Percentage engorgement was low, mostly below 10% on Merinos and below 5% on Dorpers. When high wind speeds and high saturation deficits (associated with temperatures in the mid-thirties) occurred, the success of capture was impaired. The technique is useful for quantifying the abundance of irritating blackflies in the immediate proximity of smallstock under experimental conditions.

Four to 10 Dorper sheep on each of 12 farms in the Cape Province and 3 farms in the Orange Free State were examined for adult ixodid ticks at approximately 2- to 4-weekly intervals over periods varying from 4 to 18 months, commencing during January, February or April 1989. The farms in the Cape Province were located in the north-west, south-west and south of the province. Those in the Orange Free State were situated in the north-east and in the south. The sheep in the Cape Province harboured 10 species of ixodid ticks and the seasonal abundances of Ixodes rubicundus, Rhipicephalus evertsi evertsi, Rhipicephalus gertrudae and Hyalomma truncatum were determined. The animals in the Orange Free State were infested with 7 tick species and the seasonal abundances of I. rubicundus, R. evertsi and Hyalomma marginatum rufipes were determined.

One hundred and seventeen scrub hares, Lepus saxatilis, were examined for ixodid ticks in various regions of the Cape Province. They were infested with 18 tick species and the seasonal abundances of the immature stages of Amblyomma hebraeum, Amblyomma marmoreum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum and all stages of Rhipicephalus oculatus and the adults of a Rhipicephalus sp. (near R. oculatus) were determined. Seventy-two scrub hares on 3 farms in the Orange Free State harboured 10 ixodid tick species and the seasonal abundances of the immature stages of H. marginatum rufipes and Hyalomma truncatum and all stages of Rhipicephalus punctatus were determined. Thirty Cape hares, Lepus capensis, examined in the northern Cape Province harboured 5 tick species and the seasonal abundances of the immature stages of H. marginatum rufipes and H. truncatum were determined. Thirty-four Cape hares examined in the south-western Orange Free State carried 6 tick species and the seasonal abundance of immature H. marginatum rufipes was determined on these animals. Twenty-eight Smith's red rock rabbits examined on 2 farms in the south-western Orange Free State were infested with 7 tick species.

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.

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.