Fasihah Taleo

Transmission assessment surveys (TAS) to define endpoints for lymphatic filariasis mass drug administration: a multicenter evaluation.

Background Lymphatic filariasis (LF) is targeted for global elimination through treatment of entire at-risk populations with repeated annual mass drug administration (MDA). Essential for program success is defining and confirming the appropriate endpoint for MDA when transmission is presumed to have reached a level low enough that it cannot be sustained even in the absence of drug intervention. Guidelines advanced by WHO call for a transmission assessment survey (TAS) to determine if MDA can be stopped within an LF evaluation unit (EU) after at least five effective rounds of annual treatment. To test the value and practicality of these guidelines, a multicenter operational research trial was undertaken in 11 countries covering various geographic and epidemiological settings. Methodology The TAS was conducted twice in each EU with TAS-1 and TAS-2 approximately 24 months apart. Lot quality assurance sampling (LQAS) formed the basis of the TAS survey design but specific EU characteristics defined the survey site (school or community), eligible population (6–7 year olds or 1st–2nd graders), survey type (systematic or cluster-sampling), target sample size, and critical cutoff (a statistically powered threshold below which transmission is expected to be no longer sustainable). The primary diagnostic tools were the immunochromatographic (ICT) test for W. bancrofti EUs and the BmR1 test (Brugia Rapid or PanLF) for Brugia spp. EUs. Principal Findings/Conclusions In 10 of 11 EUs, the number of TAS-1 positive cases was below the critical cutoff, indicating that MDA could be stopped. The same results were found in the follow-up TAS-2, therefore, confirming the previous decision outcome. Sample sizes were highly sex and age-representative and closely matched the target value after factoring in estimates of non-participation. The TAS was determined to be a practical and effective evaluation tool for stopping MDA although its validity for longer-term post-MDA surveillance requires further investigation.

Molecular differentiation of Treponema pallidum subspecies in skin ulceration clinically suspected as yaws in Vanuatu using real-time multiplex PCR and serological methods.

We developed a TaqMan-based real-time quadriplex polymerase chain reaction (PCR) to simultaneously detect Treponema pallidum subspecies pallidum, T. pallidum subsp. pertenue, and T. pallidum subsp. endemicum, the causative agents of venereal syphilis, yaws, and bejel, respectively. The PCR assay was applied to samples from skin ulcerations of clinically presumptive yaws cases among children on Tanna Island, Vanuatu. Another real-time triplex PCR was used to screen for the point mutations in the 23S rRNA genes that have previously been associated with azithromycin resistance in T. pallidum subsp. pallidum strains. Seropositivity by the classical syphilis serological tests was 35.5% among children with skin ulcerations clinically suspected with yaws, whereas the presence of T. pallidum subsp. pertenue DNA was only found in lesions from 15.5% of children. No evidence of T. pallidum subsp. pertenue infection, by either PCR or serology was found in ∼59% of cases indicating alternative causes of yaws-like lesions in this endemic area.

Challenges and key research questions for yaws eradication

Yaws is endemic in west Africa, southeast Asia, and the Pacific region. To eradicate yaws by 2020, WHO has launched a campaign of mass treatment with azithromycin. Progress has been made towards achievement of this ambitious goal, including the validation of point-of-care and molecular diagnostic tests and piloting of the strategy in several countries, including Ghana, Vanuatu, and Papua New Guinea. Gaps in knowledge need to be addressed to allow refinement of the eradication strategy. Studies exploring determinants of the spatial distribution of yaws are needed to help with the completion of baseline mapping. The finding that Haemophilus ducreyi causes lesions similar to yaws is particularly important and further work is needed to assess the effect of azithromycin on these lesions. The integration of diagnostic tests into different stages of the eradication campaign needs investigation. Finally, studies must be done to inform the optimum mass-treatment strategy for sustainable interruption of transmission.

Metaanalysis of the Performance of a Combined Treponemal and Nontreponemal Rapid Diagnostic Test for Syphilis and Yaws

A combined treponemal and nontreponemal rapid diagnostic test was found to have good sensitivity and specificity for both syphilis and yaws. The performance of both the treponemal and nontreponemal test components was strongly associated with the rapid plasma reagin titer.

Application of the Filariasis CELISA Antifilarial IgG4 Antibody Assay in Surveillance in Lymphatic Filariasis Elimination Programmes in the South Pacific

Elimination of lymphatic filariasis (LF) in the Pacific Island Countries and Territories (PICT) has been defined as <0.1% circulating filarial antigen (CFA) prevalence in children born after the implementation of successful mass drug administrations (MDAs). This research assessed the feasibility of CFA and antibody testing in three countries; Tonga, Vanuatu, and Samoa. Transmission is interrupted in Vanuatu and Tonga as evidenced by no CFA positive children and a low antibody prevalence and titre. Transmission is ongoing in Samoa with microfilaraemic (Mf) and CFA positive children and a high antibody prevalence and titre. Furthermore, areas of transmission were identified with Mf positive adults, but no CFA positive children. These areas had a high antibody prevalence in children. In conclusion, CFA testing in children alone was not useful for identifying areas of residual endemicity in Samoa. Thus, it would be beneficial to include antibody serology in the PICT surveillance strategy.

Tropical leg ulcers in children: more than yaws

The management of yaws has changed in recent years. Mass treatment with oral azithromycin has replaced intramuscular benzathine benzylpenicillin. Treponemal and non-treponemal serology (equivalent to TPHA and RPR) point-of-care blood testing is now available. In addition, recent studies in yaws endemic regions have shown that a significant number of leg ulcers in children which are clinically suggestive of yaws are caused by Haemophilus ducreyi. It is noteworthy that the World Health Organization has also set the ambitious goal to eliminate yaws by 2020.

Integrated Mapping of Yaws and Trachoma in the Five Northern-Most Provinces of Vanuatu.

Yaws and trachoma are targeted for eradication and elimination as public health problems. In trachoma-endemic populations mass administration of azithromycin can simultaneously treat yaws. We conducted a population-based prevalence survey in the five northernmost provinces of Vanuatu, where trachoma and yaws are suspected to be co-endemic. Clinical signs of trachoma were evaluated using the WHO simplified grading system, and skin examination with a serological rapid diagnostic test used to identify yaws. We enrolled 1004 households in 59 villages over 16 islands, and examined 3650 individuals of all ages for trachoma. The overall adjusted prevalence of trachomatous inflammation-follicular (TF) in 1–9 year-olds was 12.0% (95% Confidence Interval: 8.1–16.7%), and the overall adjusted prevalence of TT in those aged 15 years and greater was 0.04% (95% CI 0–0.14%). In multivariate analysis, the odds of children having TF was 2.6 (95% CI = 1.5–4.4) times higher in households with unimproved latrines, and independently associated with the number of children in the household (OR 1.3, 95% CI = 1.0–1.6 for each additional child). We examined the skin of 821 children aged 5–14 years. Two children had yaws, giving an estimated prevalence of active yaws in those aged 5–14 years of 0.2% (95% CI = 0.03–0.9%). Mass treatment with azithromycin is recommended in these provinces. Given the apparent low burden of yaws, integration of yaws and trachoma control programmes is likely to be useful and cost-effective to national programmes.

Sanitation and water supply coverage thresholds associated with active trachoma: Modeling cross-sectional data from 13 countries

Background Facial cleanliness and sanitation are postulated to reduce trachoma transmission, but there are no previous data on community-level herd protection thresholds. We characterize associations between active trachoma, access to improved sanitation facilities, and access to improved water sources for the purpose of face washing, with the aim of estimating community-level or herd protection thresholds. Methods and findings We used cluster-sampled Global Trachoma Mapping Project data on 884,850 children aged 1–9 years from 354,990 households in 13 countries. We employed multivariable mixed-effects modified Poisson regression models to assess the relationships between water and sanitation coverage and trachomatous inflammation—follicular (TF). We observed lower TF prevalence among those with household-level access to improved sanitation (prevalence ratio, PR = 0.87; 95%CI: 0.83–0.91), and household-level access to an improved washing water source in the residence/yard (PR = 0.81; 95%CI: 0.75–0.88). Controlling for household-level water and latrine access, we found evidence of community-level protection against TF for children living in communities with high sanitation coverage (PR80–90% = 0.87; 95%CI: 0.73–1.02; PR90–100% = 0.76; 95%CI: 0.67–0.85). Community sanitation coverage levels greater than 80% were associated with herd protection against TF (PR = 0.77; 95%CI: 0.62–0.97)—that is, lower TF in individuals whose households lacked individual sanitation but who lived in communities with high sanitation coverage. For community-level water coverage, there was no apparent threshold, although we observed lower TF among several of the higher deciles of community-level water coverage. Conclusions Our study provides insights into the community water and sanitation coverage levels that might be required to best control trachoma. Our results suggest access to adequate water and sanitation can be important components in working towards the 2020 target of eliminating trachoma as a public health problem.

Complete Genome Sequences of 11 Haemophilus ducreyi Isolates from Children with Cutaneous Lesions in Vanuatu and Ghana.

ABSTRACT Haemophilus ducreyi causes chancroid and has recently been shown to be a significant cause of cutaneous lesions in tropical or subtropical regions where yaws is endemic. Here, we report the draft genome assemblies for 11 cutaneous strains of Haemophilus ducreyi, isolated from children in Vanuatu and Ghana.

Relationships between psychosocial distress and diet during pregnancy and infant birthweight in a lower-middle income country: “Healthy mothers, healthy communities” study in Vanuatu

Abstract Background: Maternal stress during pregnancy is associated with birth outcomes, including birthweight. Exposure to natural disasters during pregnancy provides a model to study these relationships. However, few studies assess both stress and diet, which might have interactive effects. Furthermore, most are conducted in high-income countries. Patterns might differ in low- and middle-income countries (LMICs). Aim: To study relationships between stress and diet during pregnancy, and infant birthweight, following a natural disaster in a lower-middle income country. Subjects and methods: In 2015, the island nation of Vanuatu suffered a Category 5 cyclone. Three months later, the authors assessed hardship due to the cyclone, distress, and dietary diversity among 900 women, including 187 pregnant women. Of these, 70 had birth records available. Multivariate linear regression was used to analyse relationships between cyclone exposure and infant birthweight among this sub-sample. Results: Neither hardship nor dietary diversity predicted birthweight. Distress was a robust predictor, explaining 8.5% of variance (p = 0.012). There were no interactive relationships between distress and other exposure variables. Conclusions: Maternal distress following a natural disaster has important implications for maternal and child health. In LMICs, low birthweight remains a pressing public health concern. Distress during pregnancy might represent one underlying risk factor.