Putting drug use in context. Life-lines of African American women who smoke crack.

The purpose of this exploratory study was to describe a group of African American women who smoke crack. Using aggregate data from 208 interviews with women crack smokers, we randomly selected 25 women's interview data to create the 25 life-lines. These life-lines were developed in a similar manner to the time-line analysis described by Fullilove and her colleagues (1992); we focused on events that are either extraordinarily disturbing (e.g., rape, incest, death of a child, etc.), events that are usual but often stressful (e.g., birth of a child, death of a parent, etc.), and on periods of drug use. We chose this method of analysis so as to highlight the context in which many women come to use crack cocaine. The life-lines provided a retrospective (but time-ordered) perspective and in several ways provided preliminary support for a stress-diathesis perspective.

Development of Theileria mutants (Aitong) in the tick Amblyomma variegatum compared to that of T. parva (Muguga) in Rhipicephalus appendiculatus.

A comparison was made between the development of Theileria mutans (Aitong) in adult Amblyomma variegatum ticks and the development of T. parva (Muguga) in adult Rhipicephalus appendiculatus ticks. Both batches of ticks dropped as engorged nymphs from cattle whose intraerythrocytic parasitemias were approximately 40%, and it was thus possible to make a direct comparison of the infection rates produced in their tick hosts in this experiment by the 2 species of Theileria. Ticks of the 2 batches were fed in ear bags on rabbits, and equal numbers of male and female ticks were removed daily for 5 days. The salivary glands were dissected out from these ticks, and from unfed ones in each batch, processed, and examined for Theileria parasites, which were categorized according to their morphological maturity. The A. variegatum ticks had a lower rate of infection with Theileria. Fewer parasites were observed in the ticks, and they took longer to mature. When the development of the 2 species of Theileria was compared, the major difference appeared to be that T. mutans had large Babesia-like infective particles.

Establishment of an experimental field population of Theileria lawrencei-infected ticks maintained by African buffalo (Syncerus Caffer).

A population of Rhipicephalus appendiculatus ticks infected with buffalo-derived Theileria lawrencei was established in a paddock. Two infected buffalo had been introduced into this paddock which contained a small population of Theileria-free R. appendiculatus. At intervals, successive groups of Theileria-susceptible cattle were grazed with the buffalo. Transmission of T. lawrencei from buffalo to cattle was first noted 7 to 8 months after the introduction of the buffalo, this delay being accounted for by the slow buildup of the tick population and low infection rates in ticks. A T. lawrencei challenge lethal for cattle was finally achieved 10 months after the introduction of the buffalo. The paddock was then seeded with engorged R. appendiculatus female ticks and an increase in tick population occurred. The lethal challenge was observed for a further 3 years, death of exposed cattle becoming progressively more rapid as the tick population increased. The T. lawrencei challenge establsihed in the paddock may be suitable for testing the efficacy of various T. lawrencei-immunization procedures for cattle.

Babesia divergens in splenectomised calves: immunogenicity of lyophilised plasma from an infected animal.

An experiment was carried out in which three groups of splenectomised calves were inoculated on three occasions at fortnightly intervals with lyophilised plasma from an animal reacting to Babesia divergens infection. Two weeks later these three groups of calves, together with three control groups, were challengpd with isologous, homologous or heterologous isolates of B divergens. Limited protection to isologous and homologous challenge was observed in the calves inoculated with plasma.

Babesia divergens: combination of dead and live parasites in an irradiated vaccine.

Two experiments were carried out to investigate the hypothesis that the protective effect of an irradiated Babesia divergens vaccine was due to the combined inoculation of large numbers of dead parasites and small number of live ones. In the first experiment it was demonstrated that animals receiving 10(8) parasites irradiated at 25 kilorads had more severe B divergens reactions than animals in a previous experiment which had received 10(10) parasites irradiated at 24, 28 or 32 kilorads. In the second experiment it was shown that the simultaneous inoculation of 10(10) parasites killed by irradiation at 50 kilorads and 10(8) parasites irradiated at 25 kilorads resulted in the suppression of the relatively severe reactions induced by inoculation of the 25 kilorad-irradiated parasites alone. It was also shown that the simultaneous inoculation of 10(10) parasites irradiated at 50 kilorads and 10(4) live parasites similarly suppressed the anticipated reactions of the calves. These results indicated that the hypothesis was correct under the conditions of the experiment.

Babesia divergens: the immunisation of splenectomised calves during irradiated piroplasms.

Groups of three splenectomised calves were inoculated with 1 . 2 x 10(10) Babesia divergens-infected erythrocytes irradiated at 24, 28, 32, 36 and 40 kilorads. Control calves were inoculated with 1 . 2 x 10(7) or 1 . 2 x 10(4) non-irradiated parasites. While control animals all experienced severe reactions, animals receiving blood irradiated at 24, 28 and 32 kilorads had mild reactions and were solidly immune to an homologous challenge of 1 . 1 x 10(4) Babesia-infected erythrocytes. Animals receiving parasites irradiated at 36 and 40 kilorads had limited ability to resist the challenge.

Protection of cattle against Babesia major by the inoculation of irradiated piroplasms.

Two experiments were carried out on Babesia major in splenectomised calves. In the first one, the parasite was titrated and a linear relationship was observed between infective dose (10(2)--10(7) parasites) and onset of disease. In the second experiment aliquots of 1.2 X 10(10) parasites were irradiated at doses of 24, 28, 32, 36 and 40 krads and inoculated into groups of calves, while control calves received 1.2 X 10(7) or 1.2 X 10(4) parasites. Animals which received parasites irradiated at 24 or 28 krads had mild reactions and were immune to homologous challenge. Animals receiving parasites irradiated at the higher dose levels had limited ability to resist the challenge.

Babesia divergens in splenectomised calves: titration of the infective dose.

Two experiments were carried out in which Babesia divergens was titrated in splenectomised calves. In the first experiment, a linear relationship was observed between infective dose (10(5)--10(9)) parasites) and onset of disease. In the second experiment, a similar trend was observed for infective doses of 10(2)--10(6) parasites, but 10(3) parasites appeared to be the minimum dose required to produce overt disease or resistance to homologous challenge in inoculated animals.

Investigations on Babesia motasi isolated from Wales.

A number of observations were carried out on the effect of the newly isolated parasite, Babesia motasi (Wales) on intact and splenectomised sheep and on a splenectomised goat. The parasite was not pathogenic for intact animals but caused fever and anaemia in splenectomised ones. B motasi (Wales) was also studied morphologically, morphometrically and serologically. The common form of the parasite was seen to be a double pyriform, the mean length of one side being 2.23 micrometer. It appeared to be morphometrically and serologically close to the other north European B motasi strains but distinct from B motasi (Turkey). In a limited serological survey, experience of infection with B motasi appeared to be common in sheep grazing in coastal areas of North Wales, but rare in a part of South Wales known to harbour the vector tick Haemaphysalis punctata. Transovarial transmission of B motasi by H punctata took place with facility.

Development of a prophylactic regime using Terramycin/LA to assist in the introduction of susceptible cattle into heartwater endemic areas of Africa.

As a result of a personal survey in 1982, interviewing veterinarians from Louis Trichardt to Uitenhage, it was concluded that bovine heartwater is currently regarded as the most serious tick-borne disease problem in South Africa. A combination of long-acting oxytetracycline and prednisolone is regarded as the most effective therapy. The disease is almost inevitable in unprotected young high-grade susceptible stock introduced into endemic areas such as the northern Transvaal and the Valley Bushveld of Natal and the Eastern Cape. A series of trials was conducted at Settlers, Pietermaritzburg and East London on farms representative of these areas and it was demonstrated that 4 injections of 20 mg/kg of long-acting oxytetracycline on Days 0, 7, 14 and 21 after introduction enabled such stock to be introduced without the disease occurring. A further trial was carried out on the Pietermaritzburg farm, where it was shown that the number of injections could be reduced to 3, on Days 7, 14 and 21 or Days 7, 12 and 17, or even 2 on Days 7 and 14. Two points need stressing. First, these results were obtained in areas of high heartwater endemicity. Second, in order to be confident that the regimen will be effective it is necessary to have acquired knowledge of the epidemiology of the disease at the farm. Thus in the 2nd year at Pietermaritzburg we were able to use a reduced treatment regime we knew the pattern of disease occurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Parasites of domestic and wild animals in South Africa. XLV. Helminths of dairy calves on dry-land Kikuyu grass pastures in the Eastern Cape Province.

Successive pairs of approximately 4-month-old Friesland bull calves, raised under worm-free conditions, were exposed to helminth infection for 14 days on dry-land Kikuyu grass pastures at 28-day to monthly intervals, on a coastal farm in a non-seasonal rainfall region of the Eastern Cape Province. With the exception of one pair of calves exposed for 28 days, this procedure was repeated for 28 consecutive months from December 1982 to March 1985. The day after removal from the pastures one calf of each pair was slaughtered and processed for helminth recovery and the other 21 days later. Both members of the last four pairs of calves were killed 21 days after removal from the pastures. Sixteen nematode species were recovered from the calves, and infection with Ostertagia ostertagi was the most intense and prevalent, followed by Cooperia oncophora. The calves acquired the greatest number of nematodes from the pastures from June to October of the first year and from June to August of the second year of the survey. Few worms were recovered from the tracer calves examined from November or December to March or April in each year of the survey. The seasonal patterns of infection with Cooperia spp., Haemonchus placei, Nematodirus helvetianus, Oesophagostomum spp., O. ostertagi and Trichostrongylus axei were all similar and were negatively correlated to atmospheric temperature and evaporation. Slight to moderate arrest in the development of fourth stage larvae occurred from July to September in Cooperia spp., April to July in H. placei, and August to October in O. ostertagi and Trichostrongylus spp. during the first year of the survey. Too few worms were present in the second year to determine a seasonal pattern of arrest. Species survival during the hot and windy summer months appeared to be achieved via a combination of arrested larval development and an ageing residual population of adult worms in the host, and a small extant population of infective larvae on the pastures.

Isolation of a virulent strain of Ehrlichia phagocytophila from the blood of cattle in the Isle of Man.

A blood sample from a cow in the Isle of Man caused a severe Ehrlichia phagocytophila infection when inoculated into a splenectomised calf. The parasite was passaged successively into a further splenectomised calf and then into two intact animals. One of the splenectomised calves and one of the intact animals died of the infection which was characterised by causing a sustained febrile response apparently correlated with a marked invasion of monocytes by the rickettsiae.

Quinuronium sulphate for the treatment of Babesia divergens infections of splenectomised calves.

Quinuronium sulphate was inoculated into splenectomised calves at various times in relation to artificial infection of the calves with Babesia divergens. When the drug was given one day before the parasites it had no effect on the course of the infection. However, when it was given at the time of onset of fever or haemoglobinuria, development of the infection was arrested. Two weeks after therapy, recrudescences of parasites invariably occurred. In the case of animals treated at onset of fever these recrudescences were accompanied by increasing anaemia. Treated animals resisted subsequent challenge but remained as carriers of the parasite.

Larvicidal properties against Ostertagia ostertagi of the faeces of calves treated with a sustained release formulation of morantel tartrate.

An experiment was carried out to assess the effect of morantel tartrate in the faeces of calves treated with a bolus on the survival and development of Ostertagia ostertagi eggs. Since the drug delivered from the bolus greatly reduces the nematode population in an infected animal and thus the number of eggs excreted it was necessary to mix O ostertagi eggs into the faeces of calves to which boluses had been administered. In three preliminary experiments it was shown that the methods used to extract the nematode eggs from faeces of infected cattle and remix them into faeces from uninfected cattle did not appear to affect their development into larvae or their even distribution in the faeces into which they had been remixed. The concentration of morantel tartrate lethal to O ostertagi eggs was in the range 0.0015 to 0.0025 M in vitro. It was demonstrated that the presence of the drug in the faeces of dosed calves prevented the maturation of approximately 99 per cent of O ostertagi eggs to infective larvae between days 7 and 84 after the administration of a bolus and of 75 per cent on day 91. These results help to explain the well recognised effect of the bolus in cleaning pastures of O ostertagi.

Incidence of Anoplocephala perfoliata in horses examined at an Irish abattoir.

The intestinal tracts of 363 horses were examined after slaughter at a horse abattoir. The presence or absence of Anoplocephala perfoliata and the sites of attachment were recorded. A total of 51 per cent of the horses had A perfoliata attached to the mucosa of the ileocaecal junction and/or to the caecal mucosa; 5 per cent of the horses had A perfoliata attached only to the mucosa of the ileocaecal junction, 24 per cent had A perfoliata attached only to the caecal mucosa and 22 per cent of the horses had A perfoliata attached at both sites. The degree of infestation did not appear to be influenced by the season or by the age, breed or source of origin of the horses. The lesions at the sites of attachment included congestion, oedema, ulceration, diphtheresis, mucosal thickening, eosinophil infiltration and fibroplasia. The severity of the lesions was exacerbated by increasing numbers of worms.

Exposure of cattle immunised against redwater to tick-induced challenge in the field: challenge by a heterologous strain of Babesia divergens.

Eighteen, one-and-a-half-year-old Friesian heifers and a three-year-old Friesian bull were immunised against bovine redwater by inoculation with blood infected with a known strain of Babesia divergens which had been irradiated at 30 kilorads. Three weeks later these cattle plus 10 Friesian bullocks of the same age which served as controls were introduced to a grazing area infested with ticks able to transmit infections of a heterologous strain of B divergens. The control cattle all became infected with the heterologous strain, two severely. None of the inoculated cattle became clinically affected.

Exposure of cattle immunised against redwater to tick challenge in the field: challenge by a homologous strain of B divergens.

A field trial was conducted in Northern Ireland to determine whether calves could be protected against babesiosis by the prior inoculation of irradiated blood infected with Babesia divergens; The trial involved 30 yearling calves. Ten were inoculated with infected blood from a donor calf after the blood had been irradiated at 25 kilorads, and 10 with blood irradiated at 30 kilorads. Their reactions to the inoculation were observed daily for a month. They were then released, along with a control group of 10 susceptible calves, into an area heavily infested with B divergens-infected Ixodes ricinus ticks for two months. Between 24 and 41 days after exposure all the control animals contracted babesiosis and six of them reacted severely. None of the immunised animals suffered clinical babesiosis although 14 had detectable low-level infections. The relative severity of the reactions of the groups of calves was reflected in their haematology.

Long-acting oxytetracycline prophylaxis to protect susceptible cattle introduced into an area of Kenya with endemic East Coast fever.

Two field trials were carried out in successive years at the Ngong Veterinary Farm, Kenya, in which young cattle, previously unexposed to tick-borne diseases, were introduced into an area with endemic East Coast fever while protected by a series of injections of a long-acting oxytetracycline. In 1984, 12 animals which received injections of 20 mg/kg of the drug on days 0, 7, 14 and 21 after introduction, together with 12 untreated controls, were exposed without tick control until clinical disease occurred. All 12 control animals contracted East Coast fever by day 24 and 10 of them died. Five of the 12 injected animals had detectable parasites, and one of them required antitheilerial treatment. In 1985, four groups of 10 calves were introduced. One group received injections of 20 mg/kg of oxytetracycline on days 7 and 14, one group received injections on days 7, 14 and 21, and a third group received injections on days 7, 12 and 17; the fourth group (controls) had no treatment until clinical disease occurred. By day 35 all the control animals had contracted the disease and one had died despite antitheilerial treatment. Three injections of oxytetracycline suppressed the disease so that mild reactions occurred in only four animals in each group, but two injections failed to prevent severe reactions in two animals and mild reactions in four others.(ABSTRACT TRUNCATED AT 250 WORDS)

The haematology of experimentally-induced B divergens and E phagocytophila infections in splenectomised calves.

An examination was made of the haematology of spenectomised calves experimentally infected with Babesia divergens and Ehrlichia phagocytophila, inoculated separately or simultaneously. Animals infected with both pathogens had less marked changes in their haematology than those inoculated with either pathogen separately. This appeared to result from the early elimination of the more pathogenic Babesia as Ehrlichia spread through the granulocytes. The apparent suppression of Babesia by Ehrlichia would appear to merit further investigation.

Separation and recombination of Babesia divergens and Ehrlichia phagocytophila from a field case of redwater from Eire.

A blood sample received from a field case of redwater in Eire caused simultaneous infections of Babesia divergens and Ehrlichia phagocytophila when inoculated into a splenectomised calf. Each disease agent was isolated in a separate splenectomised calf by suppressive drug treatment of the other agent, and blood stabilates were made. The disease agents were inoculated synchronously or asychronously into groups of calves, whose reactions were observed. Infection with B divergens had no effect on the severity of reaction of the calves to E phagocytophila but E phagocytophila infection tended to delay the establishment of B divergens if inoculated simultaneously or one week previously. If the inoculations were simultaneous there was also a tendency for the B divergens infection to be partially or completely suppressed. There was no evidence of recrudescence of one infective agent when the other was inoculated one month later.