Soil-transmitted helminth infections remain a major public health burden in low- and middle-income countries. The traditional diagnosis by microscopic examination of fecal samples is insensitive and time-consuming. In this study, a pentaplex real-time polymerase chain reaction (PCR) was evaluated for the simultaneous detection of Ancylostoma, Necator americanus, Ascaris lumbricoides, and Strongyloides stercoralis. The results were compared with those obtained by conventional parasitological diagnostic methods. Real-time PCR was positive in 48 of 77 samples (62.3%) and microscopic examination was positive in six samples (7.8%) only (P < 0.05). In conclusion, the real-time PCR assay described in this study provides a specific and sensitive diagnostic tool for the detection of these four helminth species in epidemiological studies and monitoring of treatment programs.

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. 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 1^st–2^nd 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. 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. Lymphatic filariasis (LF) is targeted for global elimination through a strategy of repeated annual mass drug administration (MDA) to entire at-risk populations. A transmission assessment survey (TAS) is designed to evaluate whether transmission of LF is presumed to have reached a level low enough that it cannot be sustained in the absence of drug intervention and, therefore, MDA can be stopped. This multicenter operational research trial examines the value and practicality of the TAS guidelines through its implementation in 11 countries of diverse geographical and epidemiologic profiles. The field experiences support the TAS survey design methodology with particular respect to school and cluster-based sampling strategies. We found that sample sizes were age and sex representative and met the target values after factoring in estimates of non-participation rates. In 10 of 11 countries, the TAS found the number of positive cases in the evaluation unit to be no more than the statistically powered critical threshold. These results were corroborated in a follow-up TAS approximately 24 months later. We conclude the TAS is a valuable and effective tool for stopping MDA but its utility for longer-term post-MDA surveillance needs further empirical evidence and may be best supported with complementary tools and methods.

The development of antifilarial antibody responses is a characteristic feature of infection with filarial parasites. It should be possible to exploit this fact to develop tools to monitor the progress of the global program to eliminate lymphatic filariasis (LF); however, assays based on parasite extracts suffer from a number of limitations, including the paucity of parasite material, the difficulty of assay standardization and problems with assay specificity. In principle, assays based on recombinant filarial antigens should address these limitations and provide useful tools for diagnosis and surveillance of LF. The present multicenter study was designed to compare the performance of antibody assays for filariasis based on recombinant antigens Bm14, WbSXP, and BmR1. Coded serum specimens were distributed to five participating laboratories where assays for each antigen were conducted in parallel. Assays based on Bm14, WbSXP, or BmR1 demonstrated good sensitivity (>90%) for field use and none of the assays demonstrated reactivity with specimens from persons with non-filarial helminth infections. Limitations of the assays are discussed. Well-designed field studies are now needed to assess sampling methodology and the application of antibody testing to the monitoring and surveillance of LF elimination programs.

Diagnosis of human toxocariasis currently relies on serologic tests that useToxocaraexcretory-secretory (TES) antigen to detect immunoglobulin G (IgG) antibodies to the larvae. In general, however, these assays do not have adequate specificity for use in countries in which other soil-transmitted helminths are endemic. The use of recombinant antigens in these assays, however, is promising for improving the specificity of the diagnosis of toxocariasis. Toward this goal, we developed an IgG4 enzyme-linked immunosorbent assay (ELISA) involving three recombinant antigens: rTES-30USM (previously produced), rTES-26, and rTES-120. The latter two antigens were produced by reverse transcription-PCR cloning; subcloned into glutathioneS-transferase (GST)-tagged and His-tagged prokaryotic expression vectors, respectively; and expressed inEscherichia coli. The recombinant proteins were subsequently purified by affinity chromatography using GST and His-Trap resins. The diagnostic potential of each purified recombinant antigen was tested with various immunoglobulin classes (IgG, IgM, and IgE) and IgG subclasses. The IgG4 ELISA was determined to have the highest specificity and was further evaluated using a panel of serum samples. The rTES-26 IgG4 ELISA showed 80.0% (24/30 samples positive) sensitivity, and both the rTES-30USM IgG4 ELISA and rTES-120 IgG4 ELISA had 93.0% (28/30) sensitivity. Combined use of rTES-120 and rTES-30 IgG4 ELISA for the diagnosis of toxocariasis provided 100% sensitivity. The specificities of rTES-26, rTES-30USM, and rTES-120 antigens were 96.2%, 93.9%, and 92.0%, respectively. These results indicate that the development of a diagnostic test using the three recombinant antigens will allow for more-accurate detection of toxocariasis.