NTD Article Round-Up

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The Global Network will be presenting a round-up of articles on neglected tropical diseases (NTDs). Check back regularly for the latest studies. To suggest an article, you may post a comment below.

1. Associations between School- and Household-Level Water, Sanitation and Hygiene Conditions and Soil-Transmitted Helminth Infection among Kenyan School Children

Parasites and Vectors – Published August 7, 2015 Freeman MC, Chard AN, Nikolay B, Garn JV, Okoyo C, Kihara J, Njenga SM, Pullan RL, Brooker SJ, Mwandawiro CS

Soil-transmitted helminths, a class of parasitic intestinal worms, are pervasive in many low-income settings. Mass treatment, typically administered through schools, with yearly or biannual drugs is inexpensive and can reduce worm burden, but reinfection can occur rapidly. Access to and use of sanitation facilities and proper hygiene can reduce infection, but rigorous data are scarce. Among school-age children, infection can occur at home or at school, but little is known about the relative importance of WASH in transmission in these two settings.  We explored the relationships between school and household water, sanitation, and hygiene conditions and behaviors during the baseline of a large-scale mass drug administration programme in Kenya. We assessed several WASH measures to quantify the exposure of school children, and developed theory and empirically-based parsimonious models.  Results suggest mixed impacts of household and school WASH on prevalence and intensity of infection. WASH risk factors differed across individual worm species, which is expected given the different mechanisms of infection.  No trend of the relative importance of school versus household-level WASH emerged, though some factors, like water supply were more strongly related to lower infection, which suggests it is important in supporting other school practices, such as hand-washing and keeping school toilets clean.

2. Should the Goal for the Treatment of Soil Transmitted Helminth (STH) Infections Be Changed from Morbidity Control in Children to Community-Wide Transmission Elimination?

PLoS Neglected Tropical Diseases – Published August 20, 2015 Roy M. Anderson, Hugo C. Turner, James E. Truscott, T. Déirdre Hollingsworth, Simon J. Brooker

This article examines the feasibility of reaching the World Health Organization goal of mass drug administration coverage for 75% of those at-risk of soil-transmitted helminths. It weighs alternative goals to achieve morbidity control and the elimination of transmission.

We are still a long way from the 2020 target of 75%. Even if this target is reached, will it be enough to eliminate transmission and the disease arising from heavy infections with STH? If not, how should the guidelines be changed to push towards morbidity control, and ideally, the eventual elimination of transmission?

3. Impact of Community Mass Treatment with Azithromycin for Trachoma Elimination on the Prevalence of Yaws

PLoS Negelcted Tropical Diseases – Published August 4, 2015 Marks M, Vahi V, Sokana O, Chi KH, Puiahi E, Kilua G, Pillay A, Dalipanda T, Bottomley C, Solomon AW, Mabey DC

Yaws is a bacterial infection closely related to syphilis. The WHO has launched a worldwide campaign to eradicate yaws by 2020. This strategy relies on mass treatment of the whole community with the antibiotic azithromycin. Mass treatment with the same antibiotic is also recommended by WHO to treat the eye condition trachoma, but with a lower dose. This study assesses the impact of a trachoma control programme in the Solomon Islands on yaws. Following a single round of mass treatment the number of yaws cases fell significantly compared to before treatment. The findings suggest that mass treatment with the lower dose of azithromycin is also effective as a treatment for yaws. In countries where both yaws and trachoma are found it may be possible to develop an integrated strategy for both conditions.

4. Nodding Syndrome May Be Only the Ears of the Hippo

PLoS Neglected Tropical Diseases – Published August 13, 2015 Joseph Francis Wamala, Mugagga Malimbo, Floribert Tepage, Luswa Lukwago, Charles Lukoya Okot, Robert O. Cannon, Anne Laudisoit, Robert Colebunders

Epidemiological studies suggest a strong association between NS and onchocerciasis.  In this paper, the authors argue in favor of expanding the research on NS to include the study of all forms of epilepsy in onchocerciasis-endemic regions and to investigate in well-designed intervention studies whether ivermectin, with or without larviciding rivers, is able to decrease the incidence of epilepsy in onchocerciasis-endemic regions. APOC estimates there are currently 36 million people with onchocerciasis. Therefore, if 1% (equivalent to the approximate excess prevalence over non-endemic areas) were to develop epilepsy, the number of excess cases of epilepsy due to onchocerciasis would be on the order of 360,000. The authors hypothesize that most of this excess in prevalence of epilepsy is potentially preventable by increasing the coverage of ivermectin treatment and by maintaining it over many years. If it is confirmed that OV increases the risk of epilepsy, this will be an additional argument to strengthen onchocerciasis elimination plans.

5. Historical Perspective and Risk of Multiple Neglected Tropical Diseases in Coastal Tanzania: Compositional and Contextual Determinants of Disease Risk

PLoS Neglected Tropical Diseases – Published August 4, 2015 Frederick Ato Armah, Reginald Quansah, Isaac Luginaah, Ratana Chuenpagdee, Herbert Hambati, Gwyn Campbell

In the past decade, research on neglected tropical diseases (NTDs) has intensified in response to the need to enhance community participation in health delivery, establish monitoring and surveillance systems, and integrate existing disease-specific treatment programs to control overlapping NTD burdens and detrimental effects. In this paper, we evaluated the geographical distribution of NTDs in coastal Tanzania. We also assessed the collective (compositional and contextual) factors that currently determine risks to multiple NTDs using a cross sectional survey of 1253 individuals in coastal Tanzania. The results show that the effect size in decreasing order of magnitude for non-binary predictors of NTD risks is as follows: NTD comorbidities > poverty > educational attainment > self-reported household quality of life > ethnicity. Compositional (biosocial and sociocultural) factors explained more variance at the neighborhood level than at the regional level, whereas contextual factors, such as access to health services and household quality, in districts explained a large proportion of variance at the regional level but individually had modest statistical significance, demonstrating the complex interactions between compositional and contextual factors in generating NTD risks. NTD risks were inequitably distributed over geographic space, which has several important policy implications. First, it suggests that localities of high burden of NTDs are likely to diminish within statistical averages at higher (regional or national) levels. Second, it indicates that curative or preventive interventions will become more efficient provided they can be focused on the localities, particularly as populations in these localities are likely to be burdened by several NTDs simultaneously, further increasing the imperative of multi-disease interventions.

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