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.
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.
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?
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.
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.
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.
Starting this month, the Global Network will be presenting a round-up of articles on neglected tropical diseases (NTDs). Check back every month for the latest. To suggest an article, you may post a comment below.
PLoS Neglected Tropical Diseases – Published to PubMed 3/12/15 Julie R. Harris, Caitlin M. Worrell, Stephanie M. Davis, Kennedy Odero, Ondari D. Mogeni, Michael S. Deming, Aden Mohammed, Joel M. Montgomery, Sammy M. Njenga, LeAnne M. Fox, David G. Addiss
“In countries with endemic soil-transmitted helminth infections, deworming medications are widely available from multiple sources, including over the counter. However, in many countries, national programs already provide deworming medications in mass drug administrations to primary school students, as part of World Health Organization recommendations. Evaluations of the effectiveness of such medications at reducing worm burden in children is based solely on the national program’s distribution schedules, primarily because little is known about how frequently deworming medications are obtained from other sources. We investigated sources of deworming medications received by children in a Kenyan slum, finding that more than half of school-aged and preschool-aged children received deworming medications outside of a national school-based deworming program. These drugs were received from multiple sources, including chemists, healthcare centers, and at schools, via the efforts of non-governmental organizations. These data strongly indicate a need to collect data on all sources of deworming medications when evaluating the effectiveness of national school-based deworming programs.”
PLoS Neglected Tropical Diseases – Published to PubMed 3/23/15 Violeta Jimenez, Huub C. Gelderblom, Rebecca Mann Flueckiger, Paul M. Emerson, Danny Haddad
“Trachoma, the world’s leading infectious cause of blindness, is scheduled for elimination by 2020. Reaching this elimination target depends on successful implementation of the SAFE strategy (Surgery, Antibiotics, Facial cleanliness, and Environmental improvements). Annual mass antibiotic distributions are key to breaking the cycle of transmission in a community. However, it is not clear how many annual mass treatments need to be carried out in order to achieve elimination. Our study analyzes the effect of mass antibiotic distribution on different baseline prevalence levels of trachoma, in order to assess factors that affect the success of reaching elimination goals. We find that the prevailing belief, which suggests that 3 annual mass treatments can achieve local elimination of trachoma at prevalences between 10–30%, and 5 annual mass treatments for districts above this benchmark, is probably incorrect. In fact, much longer intervals may be required with “business as usual” programmatic strategies, which often include skipped years of treatment. Districts with high prevalence levels may require more intense treatment strategies to eliminate trachoma. Intensified recommendations must be implemented without delay in order to reach the 2020 elimination deadline.”
PLoS Neglected Tropical Diseases – Published to PubMed 3/19/15 Kaylee Myhre Errecaborde, William Stauffer, Martin Cetron
“The United Nations High Commission for Refugees (UNHCR) has estimated that over 40 million people are currently displaced and have variable access to health care in the country in which they reside. Populations displaced by conflict are largely disenfranchised, and high prevalence of neglected tropical diseases (NTDs) has been documented. NTDs generally affect the least advantaged people in poor societies—populations with little voice or representation. These already susceptible people become even more vulnerable when forced from their communities as internally displaced persons (IDPs), refugees, or forced migrants. To further complicate matters, many of these people of concern are under 18 years old. Children experience the greatest risk and suffer the most consequences of NTDs. As marginalized populations flee from conflict or environmental catastrophe, they are often burdened with insidious NTDs ranging from asymptomatic to overt and debilitating disease. Many suffer from chronic consequences such as malnutrition, growth stunting and developmental delays, inhibiting chances for sustainable livelihoods and making it less likely that they will successfully overcome the adversity.”
PLoS Neglected Tropical Diseases – Published to PubMed 3/25/15 Louise Lu, Chengfang Liu, Linxiu Zhang, Alexis Medina, Scott Smith, Scott Rozelle
“Soil-transmitted helminths (STHs) are parasitic intestinal worms that infect more than two out of every five schoolchildren in rural China, an alarmingly high prevalence given the low cost and wide availability of safe and effective deworming treatment. Understanding of local knowledge, attitudes, and practices regarding STHs in rural China has until now, been sparse, although such information is critical for prevention and control initiatives. This study elucidates the structural and sociocultural factors that explain why deworming treatment is rarely sought for schoolchildren in poor villages of rural China with persistently high intestinal worm infection rates. In-depth, qualitative interviews were conducted in six rural villages in Guizhou Province; participants included schoolchildren, children’s parents and grandparents, and village doctors. We found evidence of three predominant reasons for high STH prevalence: lack of awareness and skepticism about STHs, local myths about STHs and deworming treatment, and poor quality of village health care. The findings have significant relevance for the development of an effective deworming program in China as well as improvement of the quality of health care at the village level.”