Surveillance of Wuchereria bancrofti infection by anti-filarial IgG4 in urine among schoolchildren and molecular xenomonitoring in Sri Lanka: a post mass drug administration study

Abstract

Background Surveillance of hidden foci or resurgence of the bancroftian filariasis has high priority to maintain the elimination status in Sri Lanka. For the surveillance, two methods were applied in Matotagama, Matara, Sri Lanka; (i) molecular xenomonitoring (MX) by PCR to detect parasite DNA in the vector, Culex ( Cx ) quinquefasciatus and (ii) survey of anti-filarial IgG4 in urine samples from schoolchildren. Results Mosquitoes were collected monthly from index houses for 17 months (2013 to 2014) to confirm the existence of bancroftian parasite. Index houses in Matotagama had recorded microfilaria-positive cases in the recent past. Five schools were selected considering Matotagama as the catchment area and all students who presented on the day were tested for urine anti-filarial IgG4 in 2015. Wuchereria bancrofti DNA in Cx . quinquefasciatus pools were found in 14 of 17 months studied and ranged between 0 and 1.4%. The MX rate was greatly increased at least two times in the year following the driest months (March, August). A total of 735 schoolchildren were tested for urine anti-filarial IgG4. Three schools located closer to the MX area had higher positive rates, 3.4%, 3.6%, and 6.6%. Both highest positive rates of MX and urine were located in a nearer vicinity. Conclusion Monthly collections to study lymphatic filariasis (LF) transmission by MX was conducted for the first time in Sri Lanka. We observed that the filarial DNA-positive rate had an association with seasonal cycle of precipitation. More than 1% filarial DNA and > 5% anti-filarial antibody rates confirmed ongoing transmission in Matotagama. The combination of two non-invasive surveys, the urine anti-filarial IgG4 levels of schoolchildren and MX of vector mosquitoes, would be a convenient package to monitor the ongoing transmission (hotspots) of LF in the surveillance.

Dried Blood Spots (DBS): A suitable alternative to using whole blood samples for diagnostic testing of visceral leishmaniasis in the post-elimination era

“…Moreover, an effective surveillance system is essential for WHO validation/certification of VL elimination. Towards addressing such endgame challenges, an index-based surveillance approach has been proposed and implemented in endemic settings for lymphatic filariasis (LF) together with an intervention package to curb transmission [33][34]. Moreover, previous study, that implemented an index-based approach to explore the association between asymptomatic VL infection with post-kala-azar dermal leishmaniasis (PKDL) patients, provided further evidence to support this pragmatic approach for gauging residual infection since VL/PKDL transmission is highly clustered [35].…”

Deteksi Filariasis Bancrofti dengan Filariasis Test Strip (FTS) dan Perilaku Pencegahan Gigitan Nyamuk di Desa Endemis Filariasis Amban Manokwari Papua Barat

“…8 Hasil negatif ini dapat disebabkan oleh keberhasilan program MDA, 16,17 kadar antigen yang rendah pada desa dengan transmisi penularan rendah 8 dan faktor musim. 18 Rendahnya transmisi penularan berhubungan dengan keberadaan larva filaria di dalam tubuh vektor. 19 Kemampuan bertahan hidup larva filaria menjadi bentuk infektif di dalam tubuh vektor dipengaruhi oleh kemampuan bertahan hidup dan perilaku nyamuk vektor.…”

“…Penelusuran penularan dan kondisi kejadian filariasis di daerah endemis, akan lebih baik jika mengidentifikasi keberadaan antibodi filaria, dan penelusuran filaria pada tubuh vektor. 18 Sebuah penelitian di Sri Lanka menunjukkan bahwa untuk mendeteksi filaria di dalam tubuh manusia dapat menggunakan kombinasi pemeriksaan antibodi di dalam urin dan xenomonitoring larva filaria pada vektor. 18 Metode tersebut baik untuk diimplementasikan terkait faktor penularan filariasis yang komplek.…”

“…18 Sebuah penelitian di Sri Lanka menunjukkan bahwa untuk mendeteksi filaria di dalam tubuh manusia dapat menggunakan kombinasi pemeriksaan antibodi di dalam urin dan xenomonitoring larva filaria pada vektor. 18 Metode tersebut baik untuk diimplementasikan terkait faktor penularan filariasis yang komplek.…”

An update on non-invasive urine diagnostics for human-infecting parasitic helminths: what more could be done and how?

“…As an example, individuals within areas having undergone mass administration with albendazole for the treatment of ascariasis may have indeed cleared any infection, however, any diagnostic assay targeting anti- Ascaris antibodies used to assess these individuals may remain positive (Jourdan et al ., 2018). In areas where disease elimination is sought, it has been suggested that antibody-targeting assays may be appropriate for use with young children who have not yet received treatment as a means of assessing whether the transmission is still taking place (Jourdan et al ., 2018; Takagi et al ., 2019). In doing so, seroconversion rate, typically somewhere between at least 4 and 8 weeks after initial exposure, must be taken into consideration (van Grootveld et al ., 2018; Vlaminck et al ., 2019).…”