Feasibility of Onchocerciasis Elimination with Ivermectin Treatment in Endemic Foci in Africa: First Evidence from Studies in Mali and Senegal

The control of onchocerciasis, or river blindness, is based on annual or six-monthly ivermectin treatment of populations at risk. This has been effective in controlling the disease as a public health problem, but it is not known whether it can also eliminate infection and transmission to the extent that treatment can be safely stopped. Many doubt that this is feasible in Africa. A study was undertaken in three hyperendemic onchocerciasis foci in Mali and Senegal where treatment has been given for 15 to 17 years. The results showed that only few infections remained in the human population and that transmission levels were everywhere below postulated thresholds for elimination. Treatment was subsequently stopped in test areas in each focus, and follow-up evaluations did not detect any recrudescence of infection or transmission. Hence, the study has provided the first evidence that onchocerciasis elimination is feasible with ivermectin treatment in some endemic foci in Africa. Although further studies are needed to determine to what extent these findings can be extrapolated to other areas in Africa, the principle of onchocerciasis elimination with ivermectin treatment has been established

Accouchement gémellaire en milieu africain: une analyse de 10 ans dans le district de Bamako au Mali

Introduction: Le but de cette étude était de déterminer les facteurs influençant le pronostic de l'accouchement du deuxième jumeau. Méthodes: L'étude était rétrospective et a porté sur tous les cas d'accouchements gémellaires enregistrés à la maternité du Centre de Santé de Référence de la commune V du District de Bamako du 1erJanvier 2007 au 31 Décembre 2016 soit sur une période de dix ans. Résultats: Nous avons enregistré 34.899 accouchements dont 1374 accouchements gémellaires soit une fréquence de 2,54%; près de 15% étaient des primipares; 39,16% étaient référées; 69,10% et 15,5% autres sans aucun suivi prénatal. Les facteurs influençant négativement pronostic du deuxième jumeau étaient: un délai ≥ 15minutes entre les jumeaux, le recours tardif à la césarienne, la non qualification de l'accoucheur, la grossesse monochoréale, le faible poids de naissance. Par contre la parité, la réalisation de manoeuvres obstétricales n'avaient aucune influence sur le pronostic du deuxième jumeau. Conclusion: Le pronostic du deuxième jumeau est fortement influencé par un délai de naissance de plus de 15 minutes entre les jumeaux, les autres facteurs agissant comme des cofacteurs

Effect of Seasonality and Ecological Factors on the Prevalence of the Four Malaria Parasite Species in Northern Mali

Background. We performed 2 cross-sectional studies in Ménaka in the Northeastern Mali across 9 sites in different ecological settings: 4 sites have permanent ponds, 4 without ponds, and one (City of Ménaka) has a semipermanent pond. We enrolled 1328 subjects in May 2004 (hot dry season) and 1422 in February 2005 (cold dry season) after the rainy season. Objective. To examine the seasonality of malaria parasite prevalence in this dry northern part of Mali at the edge of the Sahara desert. Results. Slide prevalence was lower in hot dry than cold dry season (4.94 versus 6.85%, P=0.025). Gametocyte rate increased to 0.91% in February. Four species were identified. Plasmodium falciparum was most prevalent (74.13 and 63.72%). P. malariae increased from 9.38% to 22.54% in February. In contrast, prevalence of P. vivax was higher (10.31%) without seasonal variation. Smear positivity was associated with splenomegaly (P=0.007). Malaria remained stable in the villages with ponds (P=0.221); in contrast, prevalence varied between the 2 seasons in the villages without ponds (P=0.004). Conclusion. Malaria was mesoendemic; 4 species circulates with a seasonal fluctuation for Plasmodium falciparum

Proof-of-principle of onchocerciasis elimination with ivermectin treatment in endemic foci in Africa: final results of a study in Mali and Senegal.

BACKGROUND: Mass treatment with ivermectin controls onchocerciasis as a public health problem, but it was not known if it could also interrupt transmission and eliminate the parasite in endemic foci in Africa where vectors are highly efficient. A longitudinal study was undertaken in three hyperendemic foci in Mali and Senegal with 15 to 17 years of annual or six-monthly ivermectin treatment in order to assess residual levels of infection and transmission, and test whether treatment could be safely stopped. This article reports the results of the final evaluations up to 5 years after the last treatment. METHODOLOGY/PRINCIPAL FINDINGS: Skin snip surveys were undertaken in 131 villages where 29,753 people were examined and 492,600 blackflies were analyzed for the presence of Onchocerca volvulus larva using a specific DNA probe. There was a declining trend in infection and transmission levels after the last treatment. In two sites the prevalence of microfilaria and vector infectivity rate were zero 3 to 4 years after the last treatment. In the third site, where infection levels were comparatively high before stopping treatment, there was also a consistent decline in infection and transmission to very low levels 3 to 5 years after stopping treatment. All infection and transmission indicators were below postulated thresholds for elimination. CONCLUSION/SIGNIFICANCE: The study has established the proof of principle that onchocerciasis elimination with ivermectin treatment is feasible in at least some endemic foci in Africa. The study results have been instrumental for the current evolution from onchocerciasis control to elimination in Africa

Summary of main results.

<p>NA: not available.</p

Modified study design for the R. Faleme focus.

<p>Modified study design for the R. Faleme focus.</p

Trend in prevalence of mf in the R. Gambia focus.

*<p>Source: Diawara et al <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001825#pntd.0001825-Diawara1" target="_blank">[17]</a>.</p

Study design.

<p>Study design.</p

Location of the three study foci in Mali and Senegal.

<p>Location of the three study foci in Mali and Senegal.</p