oxytetracycline--anhydrous and Heartwater-Disease

An Ehrlichia ruminantium culture system was utilized for the anti-rickettsial evaluation of two ethnoveterinary plants, Elephantorrhiza elephantina and Aloe marlothii. Well-established E. ruminantium cultures were incubated with the plant leaf acetone extracts and compared to oxytetracycline and untreated controls. Effectivity was established by comparing the percentage parasitised cells and the calculation of both EC50 and extrapolated EC90 in microg/ml. The plant extracts were also screened for antibacterial activity using bioautography. Elephantorrhiza elephantina and A. marlothii demonstrated anti-ehrlichial activity with an EC50 of 111.4 and 64.5 microg/ml and EC90 of 228.9 and 129.9 microg/ml, respectively. The corresponding EC50 and EC90 for oxytetracycline was 0.29 and 0.08 microg/ml. Both plants appeared to produce their inhibitory activity by a similar mechanism, unrelated to that of the tetracyclines. Both the plant acetone extracts demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus (ATCC strains).

Topics: Acetone; Aloe; Animals; Anti-Bacterial Agents; Dose-Response Relationship, Drug; Ehrlichia ruminantium; Heartwater Disease; In Vitro Techniques; Microbial Sensitivity Tests; Mimosa; Oxytetracycline; Phytotherapy; Plant Extracts

Sheep originating from an heartwater-free area were immunized by the infection and treatment method, using long-acting oxytetracycline. The animals were then exposed, together with control sheep to natural infection in an enzootic area. Tick counts were made to monitor the infestation and establish a correlation between infestation by certain tick species, in particular Amblyomma variegatum, and the occurrence of cowdriosis. In some cases of death associated with ehrlichiosis and anaplasmosis in the group immunized against cowdriosis, groups of Cowdria ruminantium were found in smears of the cerebral cortex, which leaves question marks as to the real nature of immunity to cowdriosis. Furthermore, these losses show the necessity of an integrated approach to the control of diseases of livestock in a given area. The presence of Rhipicephalus e. evertsi, formerly absent from this area, was significant in this respect.

Topics: Animals; Heartwater Disease; Oxytetracycline; Seasons; Senegal; Sheep; Sheep Diseases

Two groups of castrated male adult goats (three goats/group) were infected intravenously with the Ball 3 vaccine strain of Cowdria ruminantium and treated with long-acting oxytetracycline at the onset of clinical disease 10 days later. Five weeks post-vaccination one group was challenged with a Caribbean isolate (Gardel) and the other group with a West African isolate (Mali) of C. ruminantium. Non-vaccinated controls infected with either the Gardel or Mali isolate died. All of the vaccinated animals challenged with the Gardel strain reacted and survived. The three vaccinated animals challenged with the Mali isolate also reacted and two died of heartwater.

Topics: Animals; Brain; Fluorescent Antibody Technique; Goats; Heartwater Disease; Neutrophils; Oxytetracycline; Time Factors; Vaccination

Thirty young crossbred steers were purchased from a tick-borne disease-free farm in South Africa, shown to be serologically negative to Babesia bigemina/bovis and Cowdria ruminantium, and moved to an experimental farm where babesiosis and heartwater were known to be endemic. The animals were allowed to graze as a herd on tick-infested areas of the farm for 90 days from the beginning of April but were separated into three groups of 10 for treatment. One group received a prophylactic regime of two injections of 20 mg/kg of a long-acting oxytetracycline on days 7 and 14 after introduction, one received a regime of three similar injections on days 7, 14 and 21 and the other group remained untreated prophylactically. The animals were observed early each morning in a crush, rectal temperatures being taken daily and blood smears when clinical signs of disease occurred. When clinical disease was confirmed in individual animals appropriate therapeutic treatment was implemented. In addition tick counts were made weekly. All untreated control animals required treatment for redwater between days 23 and 32 and eight of them then contracted heartwater of which five died despite therapy. Four animals from the group receiving two injections of oxytetracycline and one receiving three injections also contracted redwater but rather later. During the initial 35 day assessment period it was noticed that the majority of Boophilus ticks failed to engorge on the oxytetracycline-treated animals. In the second phase of the trial theileriosis (T. mutans-type) became evident in many animals and appeared to precipitate new or recrudescent clinical redwater and heartwater in several of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Babesiosis; Cattle; Cattle Diseases; Delayed-Action Preparations; Disease Susceptibility; Heartwater Disease; Male; Oxytetracycline; Tick Infestations

Mice immunised against the Kwanyanga stock of Cowdria ruminantium by infection and treated with oxytetracycline proved immune to challenge on day 40 and also to a second challenge on day 125 after infection. Treatment with the experimental dithiosemicarbazone gloxazone on days 59 and 73 did not abolish immunity to challenge on day 125. No persistence of the organism in immune mice that had been challenged on day 40 could be demonstrated by subinoculating blood and liver homogenate on day 126. These results are different from findings reported elsewhere with the mouse-infective Kumm stock.

Topics: Animals; Heartwater Disease; Immunity, Active; Mice; Oxytetracycline; Rickettsiaceae; Thiosemicarbazones

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)

Topics: Animals; Cattle; Cattle Diseases; Drug Administration Schedule; Evaluation Studies as Topic; Heartwater Disease; Oxytetracycline; South Africa

Five groups of Tswana-cross castrated male cattle between 20 and 30 months of age (a total of 158 animals) were transported from a ranch in a heartwater-free area of south Botswana to a feedlot near Gaborone in the east of Botswana where heartwater is endemic. On arrival, one group was vaccinated intravenously with the Onderstepoort sheep blood heartwater vaccine, one group was vaccinated intravenously with the new Onderstepoort tick-derived heartwater vaccine and a third group was vaccinated subcutaneously with this tick-derived vaccine. Vaccine reactions were blocked with long acting oxytetracycline on the first day of fever. A fourth group had a series of injections of long acting oxytetracycline on days 0, 7, 14 and 21 after arrival, and a fifth served as untreated controls. The animals remained at the feedlot for 65 days during which time they faced a low level of challenge by Amblyomma hebraeum ticks. None contracted heartwater and so they were then challenged, together with a further group of control cattle, with a dose of the sheep blood vaccine. Some animals in all groups had severe heartwater reactions and died despite therapy, but 76.7 per cent, 64.5 per cent and 74.3 per cent of the cattle in the blood vaccine, intravenous tick vaccine and long acting oxytetracycline groups respectively were resistant to challenge, compared with 48.3 per cent of the subcutaneous tick vaccine group and 36.4 per cent of the controls. It was concluded that intravenous vaccination of susceptible adult cattle with either the blood or the tick-derived vaccine needs careful monitoring in the month after vaccination and does not necessarily result in immune animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Bacterial Vaccines; Botswana; Cattle; Cattle Diseases; Heartwater Disease; Male; Oxytetracycline; Rickettsiaceae; Ticks

Topics: Animals; Delayed-Action Preparations; Heartwater Disease; Oxytetracycline; Sheep; Sheep Diseases

Pathological lesions in untreated Angora goats infected with the Ball3 strain of Cowdria ruminantium corresponded with those previously reported. A severe nephrosis was the most prominent pathological lesion in the animals treated after the 1st day of the febrile reaction. Renal ischaemia appears to be central to the pathogenesis of the kidney lesions.

Topics: Animals; Goats; Heartwater Disease; Kidney; Lung; Lymph Nodes; Myocardium; Oxytetracycline; Spleen

A study was made of the infectivity of two mouse-adapted strains of Cowdria ruminantium in mice. The Kwanyanga strain was most virulent in Balb/C mice which died nine days after infection with homogenate of liver from infected mice. CD-1 mice were least susceptible of six strains tested. The du Plessis strain of C. ruminantium was equally virulent in all six mouse strains. The du Plessis strain in CD-1 mice was used as the basis of a drug screen to detect activity against heartwater (C. ruminantium infection) and was highly predictive when active compounds were tested in sheep infected with the Ball 3 strain of C. ruminantium.

Topics: Animals; Heartwater Disease; Imidocarb; Male; Mice; Mice, Inbred Strains; Oxytetracycline; Rickettsiaceae; Sheep; Sheep Diseases; Thiosemicarbazones

Topics: Administration, Oral; Animals; Heartwater Disease; Oxytetracycline; Sheep; Sheep Diseases

Topics: Administration, Oral; Animals; Goats; Heartwater Disease; Oxytetracycline; Pharmacology; Research; Rickettsia Infections; Sheep; Sheep Diseases