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Impact of long-term treatment with ivermectin on the prevalence and intensity of soil-transmitted helminth infections.

Moncayo AL, Vaca M, Amorim L, Rodriguez A, Erazo S, Oviedo G, Quinzo I, Padilla M, Chico M, Lovato R, Gomez E, Barreto ML, Cooper PJ - PLoS Negl Trop Dis (2008)

Bottom Line: There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes.Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR = 0.06, 95% CI 0.03-0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11-0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection.The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia, Universidad San Francisco de Quito, Diego Robles y Via Interoceanica S/N, Cumbaya, Quito, Ecuador.

ABSTRACT

Background: Control of soil-transmitted helminth (STH) infections relies on the periodic and long-term administration of anthelmintic drugs to high-risk groups, particularly school-age children living in endemic areas. There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes. The current study investigated the impact of 15 to 17 years of treatment with the broad-spectrum anthelmintic ivermectin, used for the control of onchocerciasis, on STH prevalence and intensity in school-age and pre-school children.

Methods and findings: A cross-sectional study was conducted in communities that had received annual or twice-annual ivermectin treatments and geographically adjacent communities that had not received treatment in two districts of Esmeraldas Province in Ecuador. Stool samples were collected from school-age children and examined for STH infection using the Kato-Katz and formol-ether concentration methods. Samples were collected also from pre-school children and examined by the formol-ether concentration method. Data on risk factors for STH infection were collected by parental questionnaire. We sampled a total of 3,705 school-age children (6-16 years) from 31 treated and 27 non-treated communities, and 1,701 pre-school children aged 0-5 years from 18 treated and 18 non-treated communities. Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR = 0.06, 95% CI 0.03-0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11-0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection. Reduced prevalence and intensities of T. trichiura infection were observed among children not eligible to receive ivermectina, providing some evidence of reduced transmission of T. trichiura infection in communities receiving mass ivermectin treatments.

Conclusion: Annual and twice-annual treatments with ivermectin over a period of up to 17 years may have had a significant impact on T. trichiura infection. The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis. The addition of a second anthelmintic drug such as albendazole may be useful for a long-term effect on A. lumbricoides infection.

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Related in: MedlinePlus

Age-prevalence and age-intensity for Ascaris lumbricoides (graphs A and B, respectively) and Trichuris trichiura (C and D, respectively) for school-age children treated (open circles) or not treated (closed circles) with ivermectin.Shown are mean values and 95% confidence intervals.
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pntd-0000293-g001: Age-prevalence and age-intensity for Ascaris lumbricoides (graphs A and B, respectively) and Trichuris trichiura (C and D, respectively) for school-age children treated (open circles) or not treated (closed circles) with ivermectin.Shown are mean values and 95% confidence intervals.

Mentions: Ivermectin treatment was associated with a significant reduction in the prevalence of infection with any STH parasite (62.8% treated vs. 86.3% untreated children; adj. OR 0.27, 95% CI 0.15–0.47, P<0.001) The age-prevalence and age-infection intensity profiles for A. lumbricoides and T. trichiura infections in treated and non-treated children are shown in Figure 1. There were trends of age-associated declines in the prevalence and intensity of both infections. The prevalence (treated 48.9% vs. non-treated 57.3%, adjusted OR 0.96, 95% CI 0.45–2.05, P = 0.92) and intensity (GM infection intensity, treated 30.2 vs. untreated 33.7 epg; adjusted RR 1.51, 95% CI 0.81–2.82, P = 0.19) of A. lumbricoides infection was not different between children from ivermectin-treated and non-treated communities across the age groupings (Figure 1A and B) (Table 2 and 3). Both the prevalence (treated 31.1% vs. non-treated 81.5%, adjusted OR 0.06, 95% CI 0.03–0.14, P<0.001) and intensity (GM infection intensity, treated 3.9 vs. untreated 132.0 epg; adjusted RR 0.28, 95% CI 0.11–0.70, P = 0.007) of T. trichiura infection were greater in non-treated compared to treated school children at all age groups (Figure 1C and D) (Table 2 and 3). Ivermectin treatment did not appear to reduce the prevalence of hookworm infection and, in fact, the prevalence was significantly greater in treated compared to non-treated children (treated 14.8% vs. non-treated 3.9%, adjusted OR 5.53, 95% CI 1.81–16.86, P = 0.003) (Table 2).


Impact of long-term treatment with ivermectin on the prevalence and intensity of soil-transmitted helminth infections.

Moncayo AL, Vaca M, Amorim L, Rodriguez A, Erazo S, Oviedo G, Quinzo I, Padilla M, Chico M, Lovato R, Gomez E, Barreto ML, Cooper PJ - PLoS Negl Trop Dis (2008)

Age-prevalence and age-intensity for Ascaris lumbricoides (graphs A and B, respectively) and Trichuris trichiura (C and D, respectively) for school-age children treated (open circles) or not treated (closed circles) with ivermectin.Shown are mean values and 95% confidence intervals.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553482&req=5

pntd-0000293-g001: Age-prevalence and age-intensity for Ascaris lumbricoides (graphs A and B, respectively) and Trichuris trichiura (C and D, respectively) for school-age children treated (open circles) or not treated (closed circles) with ivermectin.Shown are mean values and 95% confidence intervals.
Mentions: Ivermectin treatment was associated with a significant reduction in the prevalence of infection with any STH parasite (62.8% treated vs. 86.3% untreated children; adj. OR 0.27, 95% CI 0.15–0.47, P<0.001) The age-prevalence and age-infection intensity profiles for A. lumbricoides and T. trichiura infections in treated and non-treated children are shown in Figure 1. There were trends of age-associated declines in the prevalence and intensity of both infections. The prevalence (treated 48.9% vs. non-treated 57.3%, adjusted OR 0.96, 95% CI 0.45–2.05, P = 0.92) and intensity (GM infection intensity, treated 30.2 vs. untreated 33.7 epg; adjusted RR 1.51, 95% CI 0.81–2.82, P = 0.19) of A. lumbricoides infection was not different between children from ivermectin-treated and non-treated communities across the age groupings (Figure 1A and B) (Table 2 and 3). Both the prevalence (treated 31.1% vs. non-treated 81.5%, adjusted OR 0.06, 95% CI 0.03–0.14, P<0.001) and intensity (GM infection intensity, treated 3.9 vs. untreated 132.0 epg; adjusted RR 0.28, 95% CI 0.11–0.70, P = 0.007) of T. trichiura infection were greater in non-treated compared to treated school children at all age groups (Figure 1C and D) (Table 2 and 3). Ivermectin treatment did not appear to reduce the prevalence of hookworm infection and, in fact, the prevalence was significantly greater in treated compared to non-treated children (treated 14.8% vs. non-treated 3.9%, adjusted OR 5.53, 95% CI 1.81–16.86, P = 0.003) (Table 2).

Bottom Line: There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes.Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR = 0.06, 95% CI 0.03-0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11-0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection.The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia, Universidad San Francisco de Quito, Diego Robles y Via Interoceanica S/N, Cumbaya, Quito, Ecuador.

ABSTRACT

Background: Control of soil-transmitted helminth (STH) infections relies on the periodic and long-term administration of anthelmintic drugs to high-risk groups, particularly school-age children living in endemic areas. There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes. The current study investigated the impact of 15 to 17 years of treatment with the broad-spectrum anthelmintic ivermectin, used for the control of onchocerciasis, on STH prevalence and intensity in school-age and pre-school children.

Methods and findings: A cross-sectional study was conducted in communities that had received annual or twice-annual ivermectin treatments and geographically adjacent communities that had not received treatment in two districts of Esmeraldas Province in Ecuador. Stool samples were collected from school-age children and examined for STH infection using the Kato-Katz and formol-ether concentration methods. Samples were collected also from pre-school children and examined by the formol-ether concentration method. Data on risk factors for STH infection were collected by parental questionnaire. We sampled a total of 3,705 school-age children (6-16 years) from 31 treated and 27 non-treated communities, and 1,701 pre-school children aged 0-5 years from 18 treated and 18 non-treated communities. Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR = 0.06, 95% CI 0.03-0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11-0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection. Reduced prevalence and intensities of T. trichiura infection were observed among children not eligible to receive ivermectina, providing some evidence of reduced transmission of T. trichiura infection in communities receiving mass ivermectin treatments.

Conclusion: Annual and twice-annual treatments with ivermectin over a period of up to 17 years may have had a significant impact on T. trichiura infection. The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis. The addition of a second anthelmintic drug such as albendazole may be useful for a long-term effect on A. lumbricoides infection.

Show MeSH
Related in: MedlinePlus