Knowledge, attitudes and practices during a community-level ivermectin distribution campaign in Guatemala. (1/592)

Community acceptance and participation are essential for the success of mass ivermectin chemotherapy programmes for onchocerciasis (river blindness). To explore the local understanding of the purpose of ivermectin and willingness to continue taking the drug, we performed questionnaire surveys in four communities with hyperendemic onchocerciasis after each of three ivermectin treatment rounds. More than 100 respondents participated in each KAP survey, representing the heads of 30% of the households in each community. The respondents rarely stated that the goal of the ivermectin treatment programme was to prevent visual loss. Instead, they said they were taking the drug for their general well-being, to cure the onchocercal nodule (filaria), or to cure the microfilaria, a term newly introduced by agents of the treatment programme. The principal reason identified for refusal to take ivermectin was anxiety about drug-related adverse reactions, and there were marked differences between communities in acceptance of treatment. In one community over 50% of residents initially refused to take ivermectin, although participation rates improved somewhat after programmatic adjustments. We recommend that ivermectin distribution programmes establish surveillance activities to detect where acceptance is poor, so that timely and community-specific adjustments may be devised to improve participation.  (+info)

Maintaining compliance to ivermectin in communities in two West African countries. (2/592)

We have investigated various aspects related to managing wide-scale ivermectin distribution schemes within randomized controlled trials in communities where onchocerciasis is endemic. Multiple logistic regression analysis of determinants of compliance to five doses of ivermectin in 589 people in Sierra Leone showed independent significant associations with leopard skin depigmentation, the severity of side effects of treatment, fulfilling the exclusion criteria for treatment, and long-term residence in the community. These results are useful for tailoring health promotion messages in Sierra Leone, but the associations may differ in other West African societies. In Nigeria 1847 people were interviewed about various subjective responses, including itching. None of these showed clear improvement after three years of ivermectin treatment. Positive comments about treatment were generally non-specific and similar in the placebo and ivermectin groups. Negative comments were usually related to adverse reactions, especially itching and rash, and were more common after ivermectin. The lack of any benefit attributable to ivermectin that is discernible to its recipients may make it difficult to maintain the high compliance rates needed for long periods if mass dosing programmes are to have a lasting impact on onchocerciasis. In addition, no consistent effects of ivermectin were found by measuring visual acuity, height, weight or haematocrit in comparison with placebo. This may indicate that evidence of clinical impact is very slow to develop and is hard to measure using simple objective methods after only three doses of treatment. At present it seems that parasitological, entomological and detailed ophthalmological or dermatological methods are required to demonstrate the impact of ivermectin treatment in the medium-term.  (+info)

Ivermectin distribution using community volunteers in Kabarole district, Uganda. (3/592)

Ivermectin mass distribution for the control of onchocerciasis in Uganda began in 1991. This report describes a community based ivermectin distribution programme covering two foci in the Kabarole district which have an estimated 32,000 persons infected and another 110,000 at risk. Through nodule palpation in adult males, 143 villages were identified where nodule prevalence exceeded 20%. Skin snips were also taken from a sample of the population to measure changes in community microfilarial load (CMFL) with treatment. The delivery programme was integrated into the district health management structure, and used community volunteers supervised by medical assistants from adjacent health facilities for annual ivermectin distribution campaigns. After initial efforts by the community to support distributors in-kind proved inadequate, ivermectin distributors earned money retailing condoms as part of the social marketing component of district STD/AIDS programme. Reduction in the CMFL ranged from 40-62% twelve months after the second ivermectin treatment in three villages, and from 69-84% six months after the fourth round of treatment in two villages. After four years of treatment, 85% of eligible persons were receiving ivermectin from community volunteers in each treatment cycle. Drop out rates among volunteers did not exceed 20% over the four years reported here. The direct cost of treatment was US $0.29 per person. Among the reasons for low per-person treatment costs were the strong supervisory structure, the presence of health centres in the foci and a well developed and capable district Primary Health Care management team.  (+info)

Comparison of serological and parasitological assessments of Onchocerca volvulus transmission after 7 years of mass ivermectin treatment in Mexico. (4/592)

OBJECTIVE AND METHOD: To compare the utility of an ELISA using 3 recombinant antigens with that of the skin biopsy to estimate incidence of infections in a sentinel cohort of individuals living in an endemic community in southern Mexico during a set of 11 subsequent ivermectin treatments. RESULTS: The apparent community prevalence of infection and microfilarial skin infection before and after 11 treatments with ivermectin plus nodulectomy were 78% and 13%, and 0.68 mf/mg and 0.04 mf/mg, respectively, as measured by skin biopsy. Of a group of 286 individuals participating in all surveys, a sentinel cohort of 42 mf and serologically negative individuals had been followed since 1994. The annual percentage of individuals becoming positive in this cohort was 24% (10/42), 28% (9/33), 0%, and 4.3% (1/23) in 1995, 1996, 1997 and 1998, respectively. Likewise, the incidence in children 5 years and under (n = 13) within this sentinel cohort was 15% (2/13), 18% (2/11), 0% and 11% (1/9), respectively. All individuals became positive to both tests simultaneously, indicating that seroconversion assessed infection incidence as accurately as skin biopsy in the sentinel group. CONCLUSION: Incidence monitoring of a sentinel cohort provides an estimation of the parasite transmission in the community; it is less costly than massive sampling, and a finger prick blood test might be more acceptable in some communities.  (+info)

Disposition of ivermectin and cyclosporin A in CF-1 mice deficient in mdr1a P-glycoprotein. (5/592)

The pharmacokinetics and hepatic metabolism of [3H] ivermectin (IVM) and [3H]cyclosporin A (CSA) were investigated in a subpopulation of the CF-1 mouse stock naturally deficient in mdr1a p-glycoprotein (PGP). A survey of key drug-metabolizing activities in liver fractions from PGP-deficient (-/-) or wild-type (+/+) animals indicated the two subpopulations are not different in hepatic metabolic activity and capacity. Intravenous pharmacokinetics of CSA were identical between the two groups, and results from microsomal incubations indicated similar biotransformation of IVM and CSA in liver. Intestinal excretion of [3H]IVM and [3H]CSA was enhanced in PGP (+/+) animals. Absence of PGP resulted in higher blood concentrations of IVM after oral dosing, suggesting enhanced absorption of IVM in (-/-) mice. Concentrations of [3H]IVM and [3H]CSA were always greater in the brains of (-/-) mice compared with (+/+) mice after either i.v. or oral administration. In contrast, liver concentrations of either compound were not different between (+/+) and (-/-) animals after an i.v. dose. These results show the PGP (-/-) and (+/+) subpopulations of CF-1 mice are useful for studying the role of mdr1a PGP in systemic exposure and tissue disposition of PGP substrates in the absence of metabolism differences.  (+info)

Effect of anthelmintic treatment on sexual maturation in prepubertal beef heifers. (6/592)

Heifers treated with ivermectin at weaning have been reported to reach puberty at a younger age and lighter weight than untreated heifers. We tested the hypothesis that heifers administered ivermectin would respond with earlier follicular development and a greater LH response to a 1-mg estradiol-17beta challenge (E2C) than untreated heifers. Fall-born Angus heifers (n = 32) were randomly assigned on 284 +/- 9 d of age (215.5 +/- 20.8 kg) to receive ivermectin (IVR) or albendazole (ALB), IVR + ALB, or to remain as untreated controls (CONT). Each group (n = 8) was housed separately in adjacent pens throughout the trial and managed to gain .8 kg/heifer on a ration containing 13.2% CP, 58.8% TDN, and 49.9% DM. The CONT heifers received an additional 2.27 kg/heifer of corn silage and 1.59 kg/heifer of corn daily to maintain ADG at comparable levels. Individual body weight was recorded weekly, and nematode eggs per gram (EPG) of feces were measured every 21 d. Ultrasonography was performed on alternate days starting 2 wk prior to E2C to characterize follicular wave patterns. Follicles were separated into classes (C1 [3 to 5 mm], C2 [6 to 9 mm], and C3 [10 mm]) and sizes (largest [LF], second [SLF], third [TLF], and fourth largest follicles [FLF]). The sizes of the regressing dominant follicle 1 (DF1) and the progressing dominant follicle 2 (DF2) were also determined. Serum concentrations of LH were determined from hourly jugular blood samples collected 8 to 24 h after injection of E2C. The IVR + ALB treatment group had more C3 follicles than ALB and CONT (P < .07). The IVR-treated heifers had larger TLF than ALB and CONT (P < .04). The IVR- and IVR + ALB-treated heifers had larger FLF and DF2 than ALB and CONT (P < .1). Least squares means for DF2 were 9.5 +/- .5, 8.0 +/- .4, 9.5 +/- .3 and 8.3 +/- .3 mm, for IVR, ALB, IVR + ALB and CONT, respectively (P = .02 for treatment effect). The E2C-induced serum LH concentration did not differ with respect to treatment. We conclude that heifers administered IVR display increased follicular development, supporting our earlier investigations regarding reduced age at puberty in heifers treated with IVR near weaning.  (+info)

Chemical control of Haematobia irritans with 0.5% topical ivermectin solution in cattle. (7/592)

A field trial was conducted to evaluate the efficacy of a topical formulation of ivermectin administered at the dose of 500 micrograms/kg against horn flies (Haematobia irritans) in cattle. Eighty-eight cattle in four herds naturally exposed to horn flies were used in the trial. Replicates were formed of two herds. Within replicates, one herd was randomly allocated to the untreated control and the other to the ivermectin treatment group. Horn fly counts were taken on the treatment day (Day 0) and on Days 7, 14, 21, 28, and 35 post-treatment. There were no horn flies on any cattle in the treatment group, whereas all the control cattle were continuously infested by horn flies on each examination day.  (+info)

Long-term persistence of cellular hyporesponsiveness to filarial antigens after clearance of microfilaremia. (8/592)

The persistence of parasite-specific cellular hyporesponsiveness after clearance of blood microfilariae (mf) was studied in 18 individuals who had been treated with a single dose of ivermectin, diethylcarbamazine, or a combination 2-3 years previously and who had initially cleared their parasitemia. At recruitment into the present study, 50% were again mf+ and 50% remained mf-. There were no significant differences between the mf+ and mf- groups in the amount of interferon-gamma (IFN-gamma) produced by peripheral blood mononuclear cells in response to adult or microfilarial antigens, although IFN-gamma production in response to purified protein derivative was greater in the mf+ group (geometric mean [gm] = 3,791 pg/ml; P = 0.02) than in the mf- group (gm = 600 pg/ml). These data suggest that although microfilaremic individuals may temporarily regain the ability to produce IFN-gamma to parasite antigens post-treatment, they subsequently revert to a state of hyporesponsiveness to mf-containing antigens that appears to be independent of the recurrence of microfilaremia and the response to nonparasite antigens.  (+info)