Loiasis is a filarial infection endemic in the rainforest zone of west and central Africa particularly in Cameroon, Gabon, Republic of Congo, and Democratic Republic of the Congo. Repeated treatments ...with ivermectin have been delivered using the annual community directed treatment with ivermectin (CDTI) approach for several years to control onchocerciasis in some Loa loa-Onchocerca volvulus co-endemic areas. The impact of CDTI on loiasis parasitological indicators is not known. We, therefore, designed this cross sectional study to explore the effects of several rounds of CDTI on parasitological indicators of loiasis.
The study was conducted in the East, Northwest and Southwest 2 CDTI projects of Cameroon. Individuals who consented to participate were interviewed for ivermectin treatment history and enrolled for parasitological screening using thick smears. Ivermectin treatment history was correlated with loiasis prevalence/intensity. A total of 3,684 individuals were recruited from 36 communities of the 3 CDTI projects and 900 individuals from 9 villages in a non-CDTI district. In the East, loiasis prevalence was 29.3% (range = 24.2%-34.6%) in the non-CDTI district but 16.0% (3.3%-26.6%) in the CDTI district with 10 ivermectin rounds (there were no baseline data for the latter). In the Northwest and Southwest 2 districts, reductions from 30.5% to 17.9% (after 9 ivermectin rounds) but from 8.1% to 7.8% (not significantly different after 14 rounds) were registered post CDTI, respectively. Similar trends in infection intensity were observed in all sites. There was a negative relationship between adherence to ivermectin treatment and prevalence/intensity of infection in all sites. None of the children (aged 10-14 years) examined in the East CDTI project harboured high (8,000-30,000 mf/ml) or very high (>30,000 mf/ml) microfilarial loads. Individuals who had taken >5 ivermectin treatments were 2.1 times more likely to present with no microfilaraemia than those with less treatments.
In areas where onchocerciasis and loiasis are co-endemic, CDTI reduces the number of, and microfilaraemia in L. loa-infected individuals, and this, in turn, will help to prevent non-neurological and neurological complications post-ivermectin treatment among CDTI adherents.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Onchocerciasis causes a considerable disease burden in Africa, mainly through skin and eye disease. Since 1995, the African Programme for Onchocerciasis Control (APOC) has coordinated annual mass ...treatment with ivermectin in 16 countries. In this study, we estimate the health impact of APOC and the associated costs from a program perspective up to 2010 and provide expected trends up to 2015.
With data on pre-control prevalence of infection and population coverage of mass treatment, we simulated trends in infection, blindness, visual impairment, and severe itch using the micro-simulation model ONCHOSIM, and estimated disability-adjusted life years (DALYs) lost due to onchocerciasis. We assessed financial costs for APOC, beneficiary governments, and non-governmental development organizations, excluding cost of donated drugs. We estimated that between 1995 and 2010, mass treatment with ivermectin averted 8.2 million DALYs due to onchocerciasis in APOC areas, at a nominal cost of about US$257 million. We expect that APOC will avert another 9.2 million DALYs between 2011 and 2015, at a nominal cost of US$221 million.
Our simulations suggest that APOC has had a remarkable impact on population health in Africa between 1995 and 2010. This health impact is predicted to double during the subsequent five years of the program, through to 2015. APOC is a highly cost-effective public health program. Given the anticipated elimination of onchocerciasis from some APOC areas, we expect even more health gains and a more favorable cost-effectiveness of mass treatment with ivermectin in the near future.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
...of the donation, OCP instituted a new strategy of chemotherapy in combination with vector control. In 2010, the third midterm evaluation of APOC advised the JAF that it would be premature to ...close the Programme in 2015 given the perspective of onchocerciasis elimination. ...in 2011, JAF reaffirmed its endorsement for the Programme to pursue the elimination of onchocerciasis in Africa as well as co-implementation of preventive chemotherapy interventions for other selected neglected tropical diseases (NTDs) in the context of increased support to community-level health systems strengthening.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
...of this population-based approach, the disability weights for visual impairment, blindness, and troublesome itch have changed considerably and should better reflect our ideas and beliefs as a ...society of what constitutes health. According to our updated estimates, skin disease is now the most important contributor to the burden of onchocerciasis, rather than eye disease. ...the true disease burden of onchocercal skin disease (and the burden averted by APOC) is still larger than we estimate here, as our updated estimates do not include disfiguring skin disease, or other sequelae potentially associated with onchocerciasis, such as epilepsy 14 and head-nodding syndrome 15.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The use of alternative (or complementary) treatment strategies (ATSs) i.e. differing from annual community-directed treatment with ivermectin (CDTI) is required in some African foci to ...eliminate onchocerciasis by 2025. ATSs include vector control, biannual or pluriannual CDTI, better timing of CDTI, community-directed treatment with combinations of currently available anthelminthics or new drugs, and ‘test-and-treat’ (TNT) strategies requiring diagnosis of infection and/or contraindications to treatment for decisions on who to treat with what regimen. Two TNT strategies can be considered. Loa-first TNT, designed for loiasis-endemic areas and currently being evaluated using a rapid test (LoaScope), consists of identifying individuals with levels of Loa microfilaremia associated with a risk of post-ivermectin severe adverse events to exclude them from ivermectin treatment and in treating the rest (usually >97%) of the population safely. Oncho-first TNT consists of testing community members for onchocerciasis before giving treatment (currently ivermectin or doxycycline) to those who are infected. The choice of the ATS depends on the prevalences and intensities of infection with Onchocerca volvulus and Loa loa and on the relative cost-effectiveness of the strategies for the given epidemiological situation. Modelling can help select the optimal strategies, but field evaluations to determine the relative cost-effectiveness are urgently needed.
Great strides have been made toward onchocerciasis elimination by mass drug administration (MDA) of ivermectin. Focusing on MDA-eligible areas, we investigated where the elimination goal can be ...achieved by 2025 by continuation of current practice (annual MDA with ivermectin) and where intensification or additional vector control is required. We did not consider areas hypoendemic for onchocerciasis with loiasis coendemicity where MDA is contraindicated.
We used 2 previously published mathematical models, ONCHOSIM and EPIONCHO, to simulate future trends in microfilarial prevalence for 80 different settings (defined by precontrol endemicity and past MDA frequency and coverage) under different future treatment scenarios (annual, biannual, or quarterly MDA with different treatment coverage through 2025, with or without vector control strategies), assessing for each strategy whether it eventually leads to elimination.
Areas with 40%-50% precontrol microfilarial prevalence and ≥10 years of annual MDA may achieve elimination with a further 7 years of annual MDA, if not achieved already, according to both models. For most areas with 70%-80% precontrol prevalence, ONCHOSIM predicts that either annual or biannual MDA is sufficient to achieve elimination by 2025, whereas EPIONCHO predicts that elimination will not be achieved even with complementary vector control.
Whether elimination will be reached by 2025 depends on precontrol endemicity, control history, and strategies chosen from now until 2025. Biannual or quarterly MDA will accelerate progress toward elimination but cannot guarantee it by 2025 in high-endemicity areas. Long-term concomitant MDA and vector control for high-endemicity areas might be useful.
...of the donation, OCP instituted a new strategy of chemotherapy in combination with vector control. In 2010, the third midterm evaluation of APOC advised the JAF that it would be premature to close ...the Programme in 2015 given the perspective of onchocerciasis elimination. ...in 2011, JAF reaffirmed its endorsement for the Programme to pursue the elimination of onchocerciasis in Africa as well as co-implementation of preventive chemotherapy interventions for other selected neglected tropical diseases (NTDs) in the context of increased support to community-level health systems strengthening.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
...of this population-based approach, the disability weights for visual impairment, blindness, and troublesome itch have changed considerably and should better reflect our ideas and beliefs as a ...society of what constitutes health. According to our updated estimates, skin disease is now the most important contributor to the burden of onchocerciasis, rather than eye disease. ...the true disease burden of onchocercal skin disease (and the burden averted by APOC) is still larger than we estimate here, as our updated estimates do not include disfiguring skin disease, or other sequelae potentially associated with onchocerciasis, such as epilepsy 14 and head-nodding syndrome 15.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Objective As part of a baseline data collection for assessing the impact of the African Programme for Onchocerciasis Control, to evaluate the diethylcarbamazine (DEC) patch test in ...determining the endemicity of onchocerciasis.
Method A total of 226 untreated children aged 3–5, living in four selected endemic foci, in Cameroon, Gabon and Central African Republic, were tested. Observed graded skin reactions to the patch were analysed and compared with the prevalence of onchocercal nodules and reactive skin disease in the corresponding community.
Results The proportion of children who tested positive ranged from 25.0% to 77.1%. The values were closely correlated with the prevalence of nodules, i.e. the level of endemicity for onchocerciasis.
Conclusion The DEC patch test, which has been so far used only in West African foci of onchocerciasis, can also constitute a valuable tool to evaluate the levels of endemicity of onchocerciasis in Central Africa, and to follow‐up the intensity of transmission of Onchocerca volvulus.
Objectifs Evaluation du pansement à la diéthylcarbamazine dans le cadre de la collecte de données de base pour l’évaluation de l'impact du Programme Africain de lutte contre l'Onchocercose.
Méthodes 226 enfants non traités de 3 à 5 ans, vivant dans quatre foyers endémiques sélectionnés au Cameroun, au Gabon en la République Centrafricaine ont été testés. Les degrés de réaction cutanée au patch ont été analysés et comparés à la prévalence des nodules onchocerquiens et des lésions cutanées réactives dans la communauté correspondante.
Résultats La proportion d'enfants testés positifs variait de 25,0% a 77,1%. Les valeurs étaient fortement corrélées avec la prévalence de nodules i.e. le niveau d'endémicité de l'onchocercose.
Conclusions Le test au patch DEC qui n'avait jusque làété utilisé que dans les foyers d'onchocercose ouest‐africains, peut aussi constituer un outil utile pour évaluer les niveaux d'endémicité de l'onchocercose en Afrique centrale et pour le suivi de l'intensité de la transmission de O. volvulus.
Objetivo Como parte de la recolección de datos de base para valorar el impacto del Programa Africano para el Control de la Oncocercosis, se pretendía evaluar la prueba del parche de dietilcarbamazina como herramienta para estimar la endemicidad de la oncocercosis.
Método Se realizó la prueba a 226 niños no tratados, con edades comprendidas entre los 3 y 5 años, viviendo en cuatro focos endémicos seleccionados en Camerún, Gabón y la República Central Africana. Se analizaron las reacciones cutáneas observadas frente al parche y se compararon con la prevalencia de nódulos de oncocercosis y de piel reactiva en la comunidad correspondiente.
Resultados La proporción de niños que dieron positivos estaba entre el 25.0% al 77.1%. Los valores estaban cercanamente correlacionados con la prevalencia de nódulos, es decir, el nivel de endemicidad para oncocercosis.
Conclusión La prueba del parche de dietilcarbamazina, que hasta ahora solo se ha utilizado en focos de oncocercosis del África Occidental, también podría constituirse en una herramienta valiosa para evaluar los niveles de endemicidad de oncocercosis en África Central, así como para hacer un seguimiento de la intensidad de transmisión de O. volvulus.
A three-year randomized, controlled, double-blind trial was conducted in Cameroon to determine whether ivermectin, given at three-monthly intervals and/or at high doses (800
μg/kg), had a greater ...effect on adult
Onchocerca volvulus than standard doses (150
μg/kg annually). As several patients complained of transitory subjective visual problems after treatment, some of them being of an unexpected type, we organized two series of detailed ophthalmological examinations to evaluate whether they were associated with ocular lesions. Analysis showed that these complaints were significantly more frequent in the two groups treated with high doses of ivermectin than in the reference group. In the ophthalmological examinations, the only differences recorded between the groups were a lower prevalence and mean number of microfilariae in the anterior chamber in the groups treated three-monthly, and, at the first examination round, a higher prevalence of early lesions of the iris in the group treated at high doses annually. These findings do not allow us to explain the cause of the transitory ocular complaints, nor why they were more frequent in the groups treated at high doses. However, one may conclude that using doses of ivermectin higher than the standard one should be considered with caution.
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