Exponential distribution and other distributions which mimic the exponential, fit to Tanzanian data.

<p>This figure shows the Tanzanian trachoma prevalence data as a histogram in the background along with the fits of various distributions which can mimic the exponential. The black line indicates the exponential distribution fit to the data, along with the 95% confidence interval as gray shading. All the other distributions give their best fit to the data when taking on parameter values that are consistent with the exponential, as shown by their fit within the 95% confidence interval (gray shading) of the exponential curve.</p

Elimination and Eradication of Neglected Tropical Diseases with Mass Drug Administrations: A Survey of Experts

<div><p>Background</p><p>Lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths, and trachoma are the five most prevalent neglected tropical diseases in the world, and each is frequently treated with mass drug administrations. We performed a survey of neglected tropical diseases experts to elicit their opinions on the role of mass drug administrations for the elimination of these infections.</p><p>Methodology/Principal Findings</p><p>We sent an online survey to corresponding authors who had published an article about a neglected tropical disease from 2007 to 2011. Of 825 unique authors who were invited to complete the survey, 365 (44.2%) responded, including 234 (28.4%) who answered questions regarding one of the five most prevalent neglected tropical diseases. Respondents had varying opinions about the goals of programmatic activities for their chosen neglected tropical disease, with elimination or eradication identified as the most important goal by 87% of lymphatic filariasis respondents, 66% of onchocerciasis respondents, 55% of trachoma respondents, 24% of schistosomiasis respondents, and 21% of soil-transmitted helminth respondents. Mass drug administrations, other non-medication health measures, and education were generally thought to be more important for elimination than vector control, development of a new tool, or the presence of a secular trend. Drug resistance was thought to be a major limitation of mass drug administrations for all five neglected tropical diseases. Over half of respondents for lymphatic filariasis and trachoma thought that repeated mass drug administrations could eliminate infection within ten years of the initiation of mass treatments.</p><p>Conclusions/Significance</p><p>Respondents for lymphatic filariasis, onchocerciasis, and trachoma were more enthusiastic about the prospects of elimination and eradication than were respondents for schistosomiasis or soil-transmitted helminths. Mass drug administrations were generally believed to be among the most important factors for the success of elimination efforts for each of the five neglected tropical diseases, highlighting the opportunity for integrating drug distributions.</p></div

Responses to questions about drug resistance.

*<p>Chi square test.</p

Responses to questions of target population for mass drug administrations (MDAs).

*<p>Respondents were allowed to provide more than 1 response; therefore, percentages within an NTD do not sum to 100%.</p><p>†Chi square test.</p

Reasons listed as obstacles to eradication.

<p><i>P</i> = 0.22 comparing the distribution of responses between the five neglected tropical diseases.</p

Timeline for elimination and eradication for five neglected tropical diseases.

<p>Beliefs regarding the earliest time at which (A) local elimination and (B) global eradication could be achieved in a district if repeated mass drug administrations began in 2011. LF = lymphatic filariasis, Oncho = onchocerciasis, Trach = trachoma, Schisto = schistosomiasis, STHs = soil-transmitted helminths.</p

Circumstances under which local elimination of infection could occur for each of five neglected tropical diseases.

<p>Respondents were asked under what conditions elimination could occur: mass drug administrations (MDAs) using currently available drugs, MDAs plus other health measures, other health measures alone, or only if a new diagnostic test or interventional tool were developed. Alternatively, respondents could answer that elimination was not possible under any circumstances. LF = lymphatic filariasis, Oncho = onchocerciasis, Trach = trachoma, Schisto = schistosomiasis, STHs = soil-transmitted helminths.</p

Opinions about the goal of treatment programs for five neglected tropical diseases.

<p>Eradication was defined as the permanent reduction of infection to zero worldwide, not requiring any further intervention. Elimination was defined as reduction of infection to zero in a defined geographical area, requiring continued measures to prevent re-establishment of transmission. Control was defined as reduction of infection to an acceptable level, which requires continued intervention. LF = lymphatic filariasis, Oncho = onchocerciasis, Trach = trachoma, Schisto = schistosomiasis, STHs = soil-transmitted helminths.</p

Distribution parameter estimates with 95% confidence intervals.

<p>*Shape parameter for the truncated mixed exponential refers to the proportion parameter</p><p>**Shape parameter for the truncated normal and Gumbel distributions refers to the location parameter</p><p>***Parameter 3 for the generalized gamma refers to the second shape parameter</p><p>Distribution parameter estimates with 95% confidence intervals.</p

Fit of distributions, ranked by corrected Akaike Information Criteria (AIC_c).

<p>*All distributions were truncated between a prevalence of 0 and 1</p><p>Fit of distributions, ranked by corrected Akaike Information Criteria (AIC_c).</p