A Research Agenda for Helminth Diseases of Humans: Diagnostics for Control and Elimination Programmes

Diagnostic tools appropriate for undertaking interventions to control helminth infections are key to their success. Many diagnostic tests for helminth infection have unsatisfactory performance characteristics and are not well suited for use in the parasite control programmes that are being increasingly implemented. Although the application of modern laboratory research techniques to improve diagnostics for helminth infection has resulted in some technical advances, uptake has not been uniform. Frequently, pilot or proof of concept studies of promising diagnostic technologies have not been followed by much needed product development, and in many settings diagnosis continues to rely on insensitive and unsatisfactory parasitological or serodiagnostic techniques. In contrast, PCR-based xenomonitoring of arthropod vectors, and use of parasite recombinant proteins as reagents for serodiagnostic tests, have resulted in critical advances in the control of specific helminth parasites. The Disease Reference Group on Helminths Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR) was given the mandate to review helminthiases research and identify research priorities and gaps. In this review, the diagnostic technologies relevant to control of helminth infections, either available or in development, are reviewed. Critical gaps are identified and opportunities to improve needed technologies are discussed

Epidemiological assessment of continuing transmission of\ud lymphatic filariasis in Samoa

Ongoing transmission of lymphatic filariasis (LF) was assessed in five Samoan villages by measuring microfilaraemia (Mf), circulating filarial antigen (CFA) and antibody prevalence. Compared to the other villages, Fasitoo-Tai had a significantly higher Mf prevalence (3·2%), CFA prevalence (14·6%) and antibody prevalence in children (62·0%) (P<0·05). Puapua had a significantly lower CFA prevalence (2·5%), no detectable Mf-positive individuals and significantly low antibody prevalence in children (7·9%) (P<0·05). Siufaga, previously believed to be LF-free, recorded >1% CFA prevalence and a high antibody prevalence in children (46·6%). Overall, antibody prevalence in children appeared to reflect the transmission dynamics in the villages and, in Siufaga, identified an area of ongoing transmission. The Filariasis Cellabs Enzyme-Linked Immunosorbent Assay (CELISA), based on recombinant antigen Bm14, to detect antibodies, could potentially be a promising diagnostic tool for inclusion in future surveillance in the South Pacific

Lymphatic filariasis in Oceania

Lymphatic filariasis caused by the mosquito-transmitted helminth parasite Wuchereria bancrofti is an important problem in Oceania. Of the 33 countries and territories included in this review, 24 have been found to be endemic for this disease at some time in the past, and 18 of these were classified as endemic at the start of the Global Programme to Eliminate Lymphatic Filariasis in 2000. After the implementation of large mass drug administration campaigns and (to a lesser extent) vector control over the last 15 years, only ten Oceania countries and territories were still considered to have ongoing transmission of lymphatic filariasis in 2015. Through a systematic literature search and review, we identified 79 individual studies of filariasis in Oceania that were published in 70 papers between 1995 and 2015. Data on mosquito (by species) and human infection prevalence using all currently available diagnostic tests, as well as estimates of acute and chronic filariasis morbidity, were extracted from these publications and tabulated in chronological order by country and outcome measure, noting sampling method and sample size in order to evaluate study quality and precision. No studies were identified from Micronesia; most studies in Melanesia and Polynesia were found from Papua New Guinea (PNG) (30) and French Polynesia (16), respectively. All other countries in Melanesia and Polynesia were represented by 1–7 studies except Wallis and Futuna. The systematic review identified 19 published studies of mosquito infections and 62 of human infections but only 3 on acute morbidity (all from PNG in the 1990s) and 11 on chronic morbidity. Since Oceania has a diverse set of mosquito vectors, published reviews of relative efficiencies of different mosquito genera were examined to shed light on their transmission dynamics and hence the potential for elimination of filariasis in Oceania. The review indicates the need for collation of unpublished reports and studies in addition to more geographically representative studies of remaining filariasis infection distribution, as well as quantification of the disability (acute attacks, lymphoedema, elephantiasis and hydrocoele) that will remain once transmission is interrupted, in order to plan for services to alleviate these lifelong effects