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Biomedical subjects

T M Craig

Publications and source records attributed to T M Craig.

At least 73 records · Page 4Linked to original sources
PubMed1984

Control of cyathostome infections in mares treated at parturition with ivermectin.

Six mares were treated on the day of parturition with an intramuscular injection of 0.2 mg kg-1 ivermectin and placed in a pasture free of equine parasites as soon as possible after foaling. The mares and their foals were compared with a similar group of untreated mares and foals on an adjoining pasture. The experimental data was derived from mare and foal fecal egg counts, foal necropsies and pasture larval counts. Ivermectin administered to mares on the day of parturition, when combined with movement to parasite-free pastures, significantly lowered the cyathostome (small strongyle) egg production for 4 months. This reduced cyathostome exposure was reflected in lower worm-burdens in their foals for 5 months. The results indicate that ivermectin will effectively control equine strongyles when mares and their foals are moved to parasite-free pastures.

Animals↗
PubMed1984

The role of specific immunoglobulins in antibody-dependent cell-mediated cytotoxicity assays during Babesia bovis infection.

A stabilate prepared from Babesia bovis-infected Boophilus microplus ticks was used to infect intact adult cattle. Whole sera and immunoglobulin fractions from representative sera were tested by complement fixation (CF), indirect fluorescent antibody (IFA), and antibody-dependent cell-mediated cytotoxicity (ADCC) assays. The last test utilized 51Cr-labeled chicken erythrocytes coated with Babesia bovis antigen as targets. Mononuclear cell preparations, obtained from peripheral blood of normal donors and consisting of lymphocytes with 2--6% large monocytes, were used as the source of effector cells. Antibody activity was detected by all tests between 14 and 16 days following infection. Specific IgM and IgG1 were reactive in both CF and IFA tests, although the development of high titers was attributable to IgG, alone. The ADCC activity was restricted to IgG1 fractions and was greater in those sera or fractions with greater CF activity. No activity was demonstrated in IgG2 fractions by any test used.

Animals↗
PubMed1984

Efficacy of triclabendazole against Fasciola hepatica and Fascioloides magna in naturally infected calves.

Twenty calves (8 to 12 months old), naturally infected with Fasciola hepatica and Fascioloides magna, were obtained from Brazoria, Tex. They were randomly allotted to 3 treatment groups. One group (6 calves) was given the carrier without drug, the 2nd group (7 calves) was treated with triclabendazole at 6 mg/kg of body weight, and the 3rd group (7 calves) was treated with triclabendazole at 12 mg/kg. All treatments were administered as a drench. Calves given triclabendazole (either dosage level) had a 100% reduction in F hepatica burden as compared with the untreated controls. Both treatment doses also appeared to have detrimental effect on F magna infections. Viability of all flukes was determined on the basis of movement, color, and tegumental integrity. Clinical toxic reactions were not observed in the treated calves.

Animals↗
PubMed1984

Efficacy of ivermectin against Dirofilaria immitis microfilariae in naturally infected dogs.

Ivermectin, given in a single subcutaneous dose of 200 micrograms/kg, was evaluated for its efficacy against Dirofilaria immitis microfilariae in a trial with naturally infected dogs. Sodium thiacetarsamide (2.2 mg/kg) was administered twice daily for 2 days to 2 groups of 10 dogs. Two weeks later, 1 group was treated with ivermectin, and the other group was given the vehicle. Microfilariae were not detected (by blood sample concentration techniques) in 90% of the dogs 21 days after they were treated with ivermectin. Microfilariae were not detected in samples of any dog at days 28 and 35. However, 1 dog (not the one positive at day 21) had a detectable microfilaria at day 42. One dog with pretreatment ascites, exercise-induced cough, and high microfilaremial count was anorectic and depressed 2 days after treatment with ivermectin; the clinical signs were resolved 4 days later.

Animals↗
PubMed1984

Effects of Onthophagus gazella F (Coleoptera: Scarabaeidae) on free-living strongyloids of equids.

Effects on the recently introduced dung-burying beetle, Onthophagus gazella F, on free-living stages of equine strongyles were determined on a Texas pasture. Two populations of O gazella (22 and 44 pairs) were exposed to 1-kg deposits of equine dung containing 545,000 strongyle eggs for 31 days near the end of the beetle's activity season. Weekly dung and pasture samples were taken from these plots and from control plots from which beetles were excluded to recover developing larvae. Significant differences did not occur among the 3 treatments (P less than 0.05).

Animals↗
PubMed1984

Vertical migration of infective larvae of equine strongyles in sandy clay loam.

The migration of infective strongyle larvae through sandy clay loam soil was determined by evaluating the burial of horse dung as a method of reducing parasitism in horses. Equine feces containing 325 strongyle eggs/g of feces were buried at depths of 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0, and 30.0 cm below the pasture surface in sandy clay loam soil. Herbage samples were taken periodically from above the buried feces and were analyzed to determine the maximum vertical migration of infective larvae. The greatest distance of migration was 20 cm which occurred 31 days after the feces were buried. However, the number of larvae reaching the herbage from this depth represented only 0.0004% of the eggs initially buried.

Animals↗
PubMed1983

Hypocholesterolemia and hypocortisolemia in acute and terminal Babesia bovis infections.

Sera from Babesia bovis-infected cross-bred cows and purebred steers were evaluated throughout the course of acute Babesia bovis infection for cholesterol and cortisol concentrations. Cholesterol and cortisol values of surviving cattle became markedly reduced (less than 50% of normal values) during the acute phase of the disease, Days 10-15 postinoculation, and returned to essentially normal values by the end of the 35 day experimental period. The combined control group values were approximately 2.98 mM/l cholesterol and 0.085 mM/l cortisol throughout the experimental period. The results suggest that if normal synthesis of cholesterol by hepatocytes or other tissues is not maintained, then cholesterol-derived compounds such as cortisol may not be produced at levels adequate to protect against the effects of stress and cell damage during the disease process.

Animals↗
PubMed1983

Transmission of equine cyathostomes (Strongylidae) in central Texas.

After foaling, 6 mares and their foals were placed on equine parasite-free pastures. Observations of fecal nematode eggs and pasture larvae indicated peak cyathostome egg production occurred in late August and early September, with greatest numbers of larvae on the forage appearing during October. Two foals were necropsied for parasitologic evaluations at approximately 155 days of age. Both had approximately 100,000 adult cyathostomes, mostly Cylicostephanus longibursatus, Cylicocyclus nassatus and Cyathostomum catinatum. However, there were nearly 7 times more cyathostome larvae (189,004) in the foal necropsied in October, during the autumn rise in pasture larval populations, than in the foal examined in September (27,354).

Animals↗
PubMed1983

Efficacy of ivermectin in controlling Strongyloides westeri infections in foals.

Twenty-eight foals whose dams were treated IM with ivermectin (200 micrograms/kg of body weight) on the day of parturition were compared with 35 foals whose dams were administered only the vehicle. The effect of ivermectin on the vertical transmission of Strongyloides westeri and foal heat diarrhea was determined by a comparison of results obtained in the 2 groups. Foals from treated mares had significantly fewer S westeri eggs per gram of feces from 17 to 28 days postpartum. There were no differences observed in the frequencies of severity of foal heat diarrhea between the treated and control groups. In another experiment, using the same foals, 32 foals were treated IM with ivermectin (200 micrograms/kg) at 21 days of age and were compared with 31 foals administered only the vehicle. Significantly fewer S westeri eggs were recovered from the ivermectin-treated foals on day 26 to day 32, the completion day of the trial.

Animals↗
PubMed1983

Ultrastructure of Babesia bovis sexual stages as observed in Boophilus microplus cell cultures.

Propagation of Babesia bovis in a Boophilus microplus cell line resulted in the appearance of the sexual stage of the parasite normally found only within tick intestine. These sexual stages, which possessed spike-like projections containing microtubules, were present in the medium and within cultured cells. Other ultrastructural characteristics of this sexual stage are described.

Animals↗
PubMed1982

The bovine immune response to tick-derived Babesia bovis infection: serological studies of isolated immunoglobulins.

A cryopreserved stabilate was prepared from Babesia bovis-infected Boophilus microplus ticks. The stabilate was used to infect a group of mature Bos taurus-Bos indicus cows. The survivors of the initial infection were rechallenged with the homologous stabilate 65 days later. All cows reacted parasitologically after primary challenge, and most responded serologically. With the exception of two cows, those not responding serologically died of acute babesiosis. The two that survived the primary challenge, but did not produce detectable antibody, died after secondary challenge. All serologically-positive cows survived the secondary challenge. Complement fixation and indirect fluorescent antibody tests were performed on all cows' sera and, in addition, immunoglobulin fractions were prepared and analyzed from selected sera. Both IgM and IgGl were important in the initial response. A secondary IgM response was noted by complement fixation assays. No activity was detected in any IgG2 fraction.

Animals↗
PubMed1982

Clinical and serological evidence of bovine babesiosis and anaplasmosis in St. Lucia.

One hundred fifty-nine Holstein calves were imported into St. Lucia from the U.S.A. An outbreak of babesiosis occurred 17 days post-arrival, and an outbreak of anaplasmosis occurred 5 months after importation. Sera obtained 3, 6, and 12 months post-importation revealed a high prevalence of IFA titres to Babesia bovis and B. Bigemina 3 months after arrival and an increase in titres to Anaplasma marginale 6 months after arrival. Sera obtained from native cattle from several places on the island indicated infection rates of 80, 65 and 64% with A. marginale, B. bigemina and B. bovis, respectively. The rapid card test only indicated a 25% prevalence of infection of native cattle by A. marginale. This low prevalence was probably due to deterioration of serological activity during shipment.

Anaplasma↗
PubMed1981

Serological prevalence of bovine babesiosis in Guyana.

The serological prevalence of bovine babesiosis in Guyana was determined utilising the indirect fluorescent antibody (IFA) and the complement fixation (CF) tests. Babesia bigemina IFA and CF antibody activity was detected in 80% and 40% respectively of the sera from native cattle while IFA and CF antibody activity to Babesia bovis was observed in 61% and 16% of the sera. The prevalence of antibody was compared between calves less than 6 months of age and mature cattle. There was little difference between the CF and IFA tests for B. bigemina in the calves but the prevalence of IFA antibody activity to B. bovis in calves and to B. bovis and B. bigemina was greater in adult cattle. Examination of sequential serum samples from imported calves revealed that CF antibody activity appeared earlier but by day 51 following exposure to natural infection the prevalence of antibody as determined by both tests was the same.

Animals↗