Comparison of Immunochromatographic Test (ICT) and Filariasis Test Strip (FTS) for Detecting Lymphatic Filariasis Antigen in American Samoa, 2016

Circulating filarial antigen (Ag) prevalence, measured using rapid point-of-care tests, is the standard indicator used for monitoring and surveillance in the Global Program to Eliminate Lymphatic Filariasis. In 2015, the immunochromatographic test (ICT) was replaced with the filariasis test strip (FTS), which has higher reported sensitivity. Despite differences in sensitivity, no changes in recommended surveillance targets were made when the FTS was introduced. In 2016, we conducted lymphatic filariasis surveys in American Samoa using FTS, which found higher Ag prevalence than previous surveys that used ICT. To determine whether the increase was real, we assessed the concordance between FTS and ICT results by paired testing of heparinised blood from 179 individuals (63% FTS-positive). ICT had 93.8% sensitivity and 100% specificity for identifying FTS-positive persons, and sensitivity was not associated with age, gender, or presence of microfilariae. Based on these findings, if ICT had been used in the 2016 surveys, the results and interpretation would have been similar to those reported using FTS. American Samoa would have failed Transmission Assessment Survey (TAS) of Grade 1 and 2 children with either test, and community prevalence would not have been significantly different (4.1%, 95% CI, 3.3–4.9% with FTS vs. predicted 3.8%, 95%, CI: 3.1–4.6% with ICT).

Incidence of filariasis in clinically diagnosed primary vaginal hydrocele

Background: Lymphatic filariasis is caused by a mosquito-borne parasite affecting roughly 100 million people round the world. There is consensus that hydrocele is the most frequent clinical manifestation of bancroftian filariasis. In endemic areas, about 40% of men are suffering from testicular hydrocele. With this background, the present study was aimed to find the incidence of filariasis in clinically diagnosed primary vaginal hydrocele.Methods: A hospital based prospective, cross-sectional study was conducted with 60 patients diagnosed clinically as primary vaginal hydrocele coming to the department of surgery, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pimpri, Pune, to assess the incidence of filariasis.Results: Anti-filarial antibody and circulating filarial antigen in serum were detected in 5 (8.3%). Out of 60 patients and anti-filarial antibody was detected in hydrocele fluid of 2 (3.3%) patients. 2 patients out of these 5 showed microfilaria in peripheral blood smear and eosinophilic infiltrates in histopathological examination of sac.Conclusions: In 5 out of 60 cases both anti-filarial antibody and circulating filarial antigen in serum are positive thus proving that incidence of filarial hydrocele is 8% in clinically diagnosed primary vaginal hydrocele which is supposed to be idiopathic. Even though these cases have presented as clinically primary vaginal hydrocele, they are found to be filarial hydrocele after analysis of serum and hydrocele fluid. So, it is advised that all cases of clinically diagnosed primary vaginal hydroceles should be investigated for filariasis and if not, may lead to recurrence in these cases.

Circulating filarial antigen detection in brugian filariasis

SUMMARYHuman lymphatic filariasis (LF) is a major cause of disability globally. The success of global elimination programmes for LF depends upon effectiveness of tools for diagnosis and treatment. In this study on stage-specific antigen detection in brugian filariasis, L3, adult worm (AW) and microfilarial antigenaemia were detected in around 90–95% of microfilariae carriers (MF group), 50–70% of adenolymphangitis (ADL) patients, 10–25% of chronic pathology (CP) patients and 10–15% of endemic normal (EN) controls. The sensitivity of the circulating filarial antigen (CFA) detection in serum samples from MF group was up to 95%. In sera from ADL patients, unexpectedly, less antigen reactivity was observed. In CP group all the CFA positive individuals were from CP grade I and II only and none from grade III or IV, suggesting that with chronicity the AWs lose fecundity and start to disintegrate and die. Amongst EN subject, 10–15% had CFA indicating that few of them harbour filarial AWs, thus they might not be truly immune as has been conventionally believed. The specificity for antigen detection was 100% when tested with sera from various other protozoan and non-filarial helminthic infections.

Mid-arm and epitrochlear lymphadenopathy: a clinico-radiological surprise

An 18-year-old man presented with multiple subcutaneous nodules over the anteromedial aspect of his right lower arm. Based on findings of sonography, histopathology, circulating filarial antigen test, and therapeutic response to diethylcarbazine, a diagnosis of filarial lymphadenopathy affecting mid-arm nodes and epitrochlear lymph nodes was made.

Transplacental transfer of filarial antigens fromWuchereria bancrofti-infected mothers to their offspring

SUMMARYObjective.Maternal infection has been considered to be a risk factor for filarial infection in offspring. In order to examine the influence of maternal infection in neonates, we have determined the prevalence of circulating filarial antigen (CFA) and anti-filarial antibodies in 119 maternal and corresponding cord blood samples collected from an area endemic for bancroftian filariasis.Method.Prevalence of antigenaemia was detected using Og4C3 circulating filarial antigen enzyme-linked immunosorbent assay. The presence of microfilariae was determined by filtration of a 1 ml sample through a Nuclepore membrane. Antibody isotypes (IgG, IgM, and IgE) to filarial antigen (Setariadigitataantigenic extract) were determined by enzyme linked immunosorbent assay (ELISA).Results.Microfilariae were detected in 14 cases (11·8%), whereas the Og4C3 assay could detect filarial antigen in 44·5% of pregnant mothers. Interestingly, 24·5% of samples born from CFA-positive mothers were found positive for CFA. None of the cord samples from CFA-negative mothers were found positive for CFA. No significant difference was observed in prevalence of filarial-specific IgG, IgM and IgE antibodies in CFA-positive and negative mothers. IgG antibody was detected in 60·5% of maternal and 21·8% of cord samples. IgG antibody in the cord does not differ with the antigen status of the mother. In contrast IgM and IgE antibody prevalence was significantly higher in cord from infected mothers than non-infected mothers (11·3%vs0 for IgM, 24·5%vs3·03% for IgE).Conclusion.Our study demonstrates the transplacental transfer of circulating filarial antigen from mother to cord. Filaria-specific IgM and IgE antibodies were higher in cord blood from infected mothers than from non-infected mothers. The findings of the study provide additional circumstantial evidence for pre-natal sensitization to filarial antigens developedin utero.