The genetics of ivermectin resistance in Caenorhabditis elegans. (9/284)

The ability of organisms to evolve resistance threatens the effectiveness of every antibiotic drug. We show that in the nematode Caenorhabditis elegans, simultaneous mutation of three genes, avr-14, avr-15, and glc-1, encoding glutamate-gated chloride channel (GluCl) alpha-type subunits confers high-level resistance to the antiparasitic drug ivermectin. In contrast, mutating any two channel genes confers modest or no resistance. We propose a model in which ivermectin sensitivity in C. elegans is mediated by genes affecting parallel genetic pathways defined by the family of GluCl genes. The sensitivity of these pathways is further modulated by unc-7, unc-9, and the Dyf (dye filling defective) genes, which alter the structure of the nervous system. Our results suggest that the evolution of drug resistance can be slowed by targeting antibiotic drugs to several members of a multigene family.  (+info)

Comparative cost-effectiveness of ivermectin versus topical organophosphate in feedlot yearlings. (10/284)

A replicated-pen field trial was performed under commercial feedlot conditions in western Canada to determine the cost-effectiveness of administering ivermectin to yearling beef cattle upon entry to the feedlot after the grazing season, and to establish the level of trichostrongylid gastrointestinal parasite infection in this population, as estimated by fecal egg counts. Six thousand eight hundred and eighty-three, mixed breed, yearling steers were randomly allocated upon arrival at the feedlot to one of 2 experimental groups as follows: Ivermectin, which received topical ivermectin (0.5%) at the rate of 1.0 mL/10 kg body weight; or Fenthion, which received topical fenthion (20%) at the rate of 12 mL/295 kg body weight. There were 15 pens in each experimental group. Final weight, weight gain, average daily gain, and dry matter intake to gain ratio were significantly (P < 0.05) improved in the Ivermectin group as compared with the Fenthion group. There were no significant (P > or = 0.05) differences in initial weight, days on feed, or daily dry matter intake between the experimental groups. The geometric mean fecal egg counts at the time of allocation were 14.7 eggs/5 g and 16.6 eggs/5 g for the Ivermectin and Fenthion groups, respectively (P > or = 0.05). There were no significant (P > or = 0.05) differences in morbidity or mortality between the experimental groups. In the economic analysis, the significant improvements in feedlot performance in the Ivermectin group resulted in a net economic advantage of $4.20 CDN per animal.  (+info)

A case of presumed ocular toxocariasis in a 28-year old woman. (11/284)

This is a case of presumed ocular toxocariasis in a 28-year old woman complaining of a sudden onset of nasal side field defect of the right eye. The patient had been suffering from uveitis for ten months. Fundoscopic examination of the right eye showed a rhegmatogenous retinal detachment. Furthermore, a retinochoroidal granulomatous lesion was observed nearby the tear site. Scleral buckling, cryotherapy, and gas injection(SF6, pure gas, 0.7 cc) were conducted. Mebendazole was prescribed for one month at 25 mg/kg per body weight daily. Even though the interventions resulted in the recovery of the field defect, anti-Toxocara IgG and IgE titer levels did not decrease when checked three months after the treatment ended. This is the first confirmed serological ocular toxocariasis case in Korea. Uveitis may be a clinical presentation prior to retinal detachment of a person with toxocariasis.  (+info)

Pharmacokinetics of UMF-078, a candidate antifilarial drug, in infected dogs. (12/284)

The pharmacokinetics of the filaricidal benzimidazole compounds UMF-078 and UMF-289 were evaluated in beagle dogs experimentally infected with Brugia pahangi. Twenty-four infected microfilaremic beagles were selected and randomly allocated into 4 treatment groups of 6 dogs each: oral (PO) UMF-078, PO UMF-289 (the HCl salt form of UMF-078), intramuscular (IM) UMF-078, and untreated controls. Equivalent doses of 50 mg/kg of the free base were given twice a day for 3 days to the 3 groups of treated dogs. Oral absorption is rapid compared with IM dosing; the absorption half-life (K01-HL) for the IM treatment is approximately 14 hr compared with 1 and 2 hr for the PO regimen of salt and free base forms, respectively. The elimination half-lives (K10-HL) for the PO regimens are 13 and 15 hr for the salt and free base forms, respectively. Because of sustained absorption following IM dosing, the K10-HL is prolonged. In contrast to oral administration, IM dosing of UMF-078 provides sustained, relatively low plasma drug levels, with good tolerance and efficacy.  (+info)

Multilocular pyogenic hepatic abscess complicating ascaris lumbricoides infestation. (13/284)

A 74-year-old man was admitted to our hospital with frequent right flank pain. The multiple multilocular hepatic abscesses were revealed by computed tomography. Radiographs following a barium meal showed a linear filling defect in the ileum consistent with ascariasis. One day after treatment with pyrantel pamoate, an Ascaris was passed in the stool. The pyogenic hepatic abscesses gradually healed with both antibiotics and continuous drainage. After 2 months, he was discharged. In this case, the pyogenic hepatic abscesses were thus considered to have been caused by an inflammation which spread through the portal vein.  (+info)

Endocrine studies in ivermectin-treated heifers from birth to puberty. (14/284)

Continuous treatment with ivermectin from birth to puberty advanced sexual maturation by 3.7 wk in Holstein heifers grazing pastures naturally infected with nematodes. Every 14 d jugular blood samples were taken from birth to 45 wk of age from all heifers. No differences in serum FSH, estradiol, or thyroxine levels were observed during the trial between the treated and untreated group. Mean LH levels were diminished in untreated heifers 4 wk before the first estrus and the amplitude of LH pulses was augmented in treated heifers when puberty was reached. Serum IGF-I levels increased from birth to 22 wk of age and then reached a plateau in both groups, but levels were consistently higher in treated heifers from 26 wk of age onward. Body weight gain was retarded in parasitized heifers and IGF-I values were positively correlated with body weight only during the first 20 wk of life. We suggest that enhanced prepubertal IGF-I levels in conjunction with increased prepubertal LH levels and pubertal LH pulse amplitude might be involved in the accelerated somatic maturation and in puberty advancement observed in ivermectin-treated heifers.  (+info)

Treatment of cutaneous larva migrans. (15/284)

Cutaneous larva migrans caused by the larvae of animal hookworms is the most frequent skin disease among travelers returning from tropical countries. Complications (impetigo and allergic reactions), together with the intense pruritus and the significant duration of the disease, make treatment mandatory. Freezing the leading edge of the skin track rarely works. Topical treatment of the affected area with 10%-15% thiabendazole solution or ointment has limited value for multiple lesions and hookworm folliculitis, and requires applications 3 times a day for at least 15 days. Oral thiabendazole is poorly effective when given as a single dose (cure rate, 68%-84%) and is less well tolerated than either albendazole or ivermectin. Treatment with a single 400-mg oral dose of albendazole gives cure rates of 46%-100%; a single 12-mg oral dose of ivermectin gives cure rates of 81%-100%.  (+info)

Epidemiology and control of enterobiasis in a developmental center. (16/284)

OBJECTIVE: To determine if enterobiasis could be controlled in a developmental center. DESIGN: Population-based study. Annual screening of all residents by perianal swabs for enterobiasis and on admission or discharge. Treatment of infected residents and their contacts with mebendazole, 100 mg orally, with two doses given 14 days apart. MAIN OUTCOME MEASURES: The number of residents with enterobiasis and the cost of the program. RESULTS: The prevalence of enterobiasis fell rapidly and progressively, from 21% before mass medication to 1% after 3 years. CONCLUSION: Mass medication of residents with enterobiasis and their contacts was beneficial, harmless, and cost effective.  (+info)