Ovarian Filariasis: Diagnosis by detection of microfilariae in follicular fluid, a case report.

Filariasis is a common parasitic infection in India. It is rare to find neglected cases of Filariasis nowadays. We reported the presence of microfilaria species in the follicular fluid of an egg donor undergoing an ovum pick up procedure. She was a 23-year-old egg donor who underwent stimulation using the GnRH antagonist protocol. Antagonist protocol is one of the standard protocols used for controlled ovarian hyperstimulation as a part of the IVF/ICSI(in-vitro fertilization / intracytoplasmic sperm injection) procedure where GnRH antagonist (cetrorelix) is used to suppress the endogenous LH surge. Her baseline investigations were normal, with no significant history suggestive of any worm infestations. During the ovum pickup procedure, follicular fluid revealed the presence of worm-like structures suggestive of larvae of some parasites. The follicular fluid was sent to the microbiology department along with the blood sample to confirm the parasite species. The parasite was found to be the larvae of W. Bancroft. The oocytes were of poor quality and were discarded. The patient was treated with Diethylcarbamazine citrate. There are so many reports about scrotal Filariasis, but rare literature quotes ovarian Filariasis.

Morphological and genetic variation of Wuchereria bancrofti microfilariae in carriers in Thailand, Lao PDR and Myanmar: evaluation using Giemsa-stained thick blood films.

There is geographical variation in the morphology and genetics of Wuchereria bancrofti, the major cause of human lymphatic filariasis. This study aims to compare morphological and genetic variation of W. bancrofti microfilariae recovered from carriers in Lao PDR, Myanmar and Thailand. Six morphological parameters (body length, cephalic space length and width, length of head to nerve ring, body width at nerve ring, Innenkȍrper length and number of column nuclei between the cephalic space and nerve ring) were evaluated from microfilariae in Giemsa-stained thick blood films. A portion of the cytochrome c oxidase subunit 1 gene of mitochondrial DNA was sequenced and analysed. Wuchereria bancrofti microfilariae showed a wide variation in their morphology and morphometry among three countries. Phylogenetic analysis confirmed that all microfilariae belonged to W. bancrofti. Higher mutation frequencies were observed in samples from Myanmar, relative to Thailand and Lao PDR. This study highlights the morphological disparities of microfilariae and genetic variability within W. bancrofti among three geographical locations. We found that reported morphometric differences between localities were less clear-cut than previously thought. Further studies are needed to determine the microfilarial periodicity in Lao PDR.

Association of a PD-L2 Gene Polymorphism with Chronic Lymphatic Filariasis in a South Indian Cohort.

Lymphatic filariasis (LF) is a parasitic infection, caused by three closely related nematodes, namely Wuchereria bancrofti, Brugia malayi, and Brugia timori. Previously, we have shown that lysate from B. malayi microfilariae induces the expression of interleukin (IL)-10 and programmed death-ligand (PD-L) 1 on monocytes, which lead to inhibition of CD4+ T-cell responses. In this study, we investigated associations of IL-10 and programmed cell death (PD)-1 pathway gene polymorphisms with clinical manifestation in LF. We evaluated the frequency of alleles and genotypes of IL-10 (rs3024496, rs1800872), IL-10RA (rs3135932), IL-10RB (rs2834167), PD-1 (rs2227982, rs10204525), PD-L1 (rs4143815), PD-L2 (rs7854413), and single-nucleotide polymorphisms (SNPs) in 103 patients with chronic pathology (CP), such as elephantiasis or hydrocele and 106 endemic normal (EN) individuals from a South Indian population living in an area endemic for LF. Deviations from the Hardy-Weinberg equilibrium were tested, and we found a significant difference between the frequency of polymorphisms in PD-L2 (rs7854413; P < 0.001) and IL-10RB (rs2834167; P = 0.012) between the CP and the EN group, whereas there were no significant differences found among IL-10, IL-10RA, PD-1, and PD-L1 SNPs. A multivariate analysis showed that the existence of a CC genotype in PD-L2 SNP rs7854413 is associated with a higher risk of developing CP (OR: 2.942; 95% confidence interval [CI]: 0.957-9.046; P = 0.06). Altogether, these data indicate that a genetically determined individual difference in a non-synonymous missense SNP of PD-L2 might influence the susceptibility to CP.

Comparison of the Impact of Annual and Semiannual Mass Drug Administration on Lymphatic Filariasis Prevalence in Flores Island, Indonesia.

We compared the impact of annual and semiannual mass drug administration (MDA) on the prevalence of Brugia timori and Wuchereria bancrofti in Flores Island. Two villages (Paga, B. timori only; Lewomada, co-endemic) received annual MDA with diethylcarbamazine/albendazole and a larger village (Pruda, co-endemic) received semiannual MDA. Infection parameters (microfilariae [Mf], antibodies to recombinant filarial antigen BmR1 [Brugia Rapid (BR)], and a test for W. bancrofti antigenemia [immunochromatographic test (ICT)]) were assessed before and after treatment. The crude Mf prevalence in Pruda decreased after five semiannual treatments from 14.2% to 1.2%, whereas the Mf prevalence in the other two villages decreased after three annual treatments from 3.9% to 0% and from 5% to 0.3%, respectively. ICT positivity prevalence in Pruda and Lewomada decreased from 22.9% and 6.5% to 7% and 0.8%, respectively, whereas BR antibody prevalence in Pruda, Lewomada, and Paga decreased from 28.9%, 31.7%, and 12.5% to 3.6%, 4.1%, and 1.8%, respectively. Logistic regression analysis indicated that that Mf, BR, and ICT prevalence decreased significantly over time and that for the Mf and ICT outcomes the semiannual treatment had higher odds of positivity. Model-adjusted prevalence estimates revealed that apparent differences in treatment effectiveness were driven by differences in baseline prevalence and that adjusted prevalence declined more rapidly in the semiannual treatment group. We conclude that in this setting, annual MDA was sufficient to reduce Mf prevalence to less than 1% in areas with low to moderate baseline prevalence. Semiannual MDA was useful for rapidly reducing Mf prevalence in an area with higher baseline endemicity.

Immunodiagnostic potential of Wuchereria bancrofti L1 antigen-based filarial immunoglobulin G4 detection assay.

Background: After mass drug administration to eliminate human lymphatic filariasis, there is a need for surveillance to detect the measurable endpoint of the program. Methods: An immunodominant seroreactive clone, WbL1, was identified through immunoscreening of a Wuchereria bancrofti L3 complementary DNA expression library. Recombinant WbL1 (rWbL1) was analysed with sera from W. bancrofti patients. Diagnostic evaluation was carried out by developing an enzyme-linked immunosorbent assay (ELISA) to detect the filarial-specific antibodies in various categories of filarial sera samples against recombinant WbL1 (rWbL1) protein. Results: Performance parameters of the test in terms of immunoglobulin G (IgG) and IgG4 detection displayed significant sensitivity and specificity values up to 77% and 100%, respectively. Our results showed filarial antibodies against rWbL1 to be highly reactive with microfilaremic and clinical filarial sera samples compared with the endemic and non-endemic control sera samples. Reasonably satisfactory performance of the test was also confirmed from the multicentric evaluation of an anti-WbL1 IgG4 detection ELISA. This test was found to be minimally reactive with other nematode parasites and protozoan infections. Conclusions: The anti-WbL1 IgG4 detection test can be considered as a field test for initial screening and epidemiological monitoring of filarial infections in filariasis-endemic areas.

Circulating filarial antigen detection in brugian filariasis.

Human 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.

Prevalence of lymphatic filariasis in a tea garden worker population of Dibrugarh (Assam), India after six rounds of mass drug administration.

BACKGROUND & OBJECTIVES: Lymphatic filariasis (LF) is endemic in the state of Assam and mass drug administration (MDA) programme for LF elimination is being implemented in the state since 2004. A study on prevalence of microfilaria (mf), disease endemicity and vector infection was carried out in a tea garden population of Dibrugarh, Assam (India) to assess the effect of ongoing MDA programme on elimination of LF. METHODS: Finger prick thick blood smears (20 mm3) were made from individuals aged ≥2 yr old during night blood survey in between 2000-0000 hrs during the period of November 2012 to February 2013. Blood smears were dehaemoglobinised, stained with Giemsa and examined under microscope for presence of mf. Indoor resting mosquitoes were collected during 0600-1000 hrs and female Culex quinquefasciatus were dissected and examined under microscope for larval forms of the parasite. RESULTS: A total of 634 blood smears were collected and screened for mf and 47 (7.41%) individuals were found microfilaraemic, with predominance of males (74.5%). Highest mf rate (20.0%) was seen in the males of 30-39 yr age group while in females, age group of 10-19 yr recorded maximum mf rate (5.48%). Entomological collection and dissection of Cx. quinquefasciatus revealed presence of larval stages of the parasite and infection and infectivity rates recorded were 13.20 and 3.70%, respectively. Chronic clinical manifestations in the form of elephantiasis and hydrocele were recorded in 33 (5.73%) subjects of the 575 examined. INTERPRETATION & CONCLUSION: Mass drug administration data showed six rounds of MDA with drug distribution coverage in between 63.42 and 95.93% in the study population. Out of 634 individuals examined 47 were found microfilaraemic giving an overall infection rate of 7.41%. Mosquito vector infection and infectivity rates were 13.20 and 3.70%, respectively. Presence of high mf rate, vector infectivity rate and clinical cases in the study population after six rounds of MDA warrants concerted efforts to be made for effective implementation and monitoring of MDA for success of LF elimination programme.

Evidence for stopping mass drug administration for lymphatic filariasis in some, but not all local government areas of Plateau and Nasarawa States, Nigeria.

An average of six annual rounds of ivermectin and albendazole were distributed in Plateau and Nasarawa States, Nigeria, to eliminate lymphatic filariasis. From 2007 to 2008, population-based surveys were implemented in all 30 local government areas (LGAs) of the two states to determine the prevalence of Wuchereria bancrofti antigenemia to assess which LGA mass drug administration (MDA) could be halted. In total, 36,681 persons from 7,819 households were examined for filarial antigen as determined by immunochromatographic card tests. Overall antigen prevalence was 3.05% (exact upper 95% confidence interval [CI] = 3.41%) with an upper 95% CI range by LGA of 0.50-19.3%. Among 3,233 children 6-7 years of age, overall antigen prevalence was 1.71% (exact upper 95% CI = 2.19%), too high to recommend generally halting MDA in the two-state area. However, based on criteria of < 2% antigenemia among persons > 2 years of age, stopping MDA was recommended for 10 LGAs.

Bacillus sphaericus in the adults of Culex quinquefasciatus mosquitoes emerged from treated larvae and its effect on development of the filarial parasite, Wuchereria bancrofti.

Bacillus sphaericus is a bio-control agent effective against Culex quinquefasciatus, the vector of bancroftian filariasis. Apart from its larvicidal effect, there are reports of reduced infection of filarial parasites in mosquitoes exposed to it. In the present study, adults of Cx. quinquefasciatus emerged from B. sphaericus treated larvae were fed on blood samples positive for microfilariae of Wuchereria bancrofti and examined at various time intervals to assess the infection level. The rate of infection was reduced from 95% on day 1 post-feeding to 75% on day 13, when fed with blood sample containing 41 mf/20 µl. The mean parasite burden was also reduced from 4.9 per mosquito on day 1 to 2.15 on day 13. When fed with another sample (30 mf/20 µl), the infection was reduced from 100% on day 1 to 80% on day 13. Reduction in parasite burden was 4.0 to 1.75. Abnormally developed second-stage larvae of the parasite were seen in treated mosquitoes. Thus, the results indicated adverse effect of B. sphaericus treatment on infection and development of the filarial parasite in mosquitoes. The possible reason for the parasite regulation was studied through the assessment of the carryover of the bacterium as well as its toxins to the surviving mosquitoes. The presence of B. sphaericus was determined through plating of homogenate of survived mosquitoes on NYSM agar. Toxic protein was detected through immunoblotting. The bacterium as well as its 41.9-kDa toxic protein was found to be transmitted from larvae to adults and affected the parasite development, directly by the toxin or indirectly by eliciting humoral immune response of the mosquito.

Filariasis presenting as multiple subcutaneous nodules: a rare case report.

Filariasis presenting as multiple subcutaneous nodules is very rare and only a very few cases are reported in the literature. Microfilaria bancrofti is known to occur in different sites like breast, thyroid, lymph nodes, liver, lungs and body fluids, however, in contrast to the other filarial species, its occurrence in soft tissues is rarely reported. Conventional method of diagnosis of filariasis is by demonstration of microfilaria in peripheral blood smear which may be diurnal or nocturnal. The various species are differentiated by the morphological features like presence or absence of sheath, granules and nuclear arrangement in the tail end. We hereby report an unusual case of Wuchereria bancrofti infestation diagnosed on biopsy of subcutaneous nodule in a patient whose initial clinical presentation was of urticarial rashes over the upper extremities. In differential diagnosis of various subcutaneous nodular masses the possibility of filarial granuloma must be kept and a careful search should be done for adult worm or microfilaria in the serial tissue sections.

Crucial epitopes of Wuchereria bancrofti abundant larval transcript recognized in natural infection.

Lymphatic filariasis is a tropical disease, with over 40 million people seriously incapacitated due to lymphangitis and elephantiasis. Over 99% of infections are caused by the nematode Wuchereria bancrofti. Expressed sequence tag (EST) analysis of filarial genome identified novel infective larval (L3) stage-specific antigen, abundant larval transcript (ALT-2), which was shown to be highly essential for parasite establishment and survival in the host. The unique structural features and immunological characteristics of ALT-2 indicate the presence of critical motifs that needs to be explored in natural human infection for understanding and management of the disease. In order to dissect the epitopes of ALT protein recognized in humans, eight peptides spanning the entire protein sequence were selected based on in-silico epitope prediction and synthesized. Analysis of the reactivity of W. bancrofti ALT-2 synthetic peptides with clinical sera (n = 40) from endemic areas identified epitopes recognized by putatively immune sera, of which two comprise the highly variable acidic domain (21-60). Interestingly, our study also revealed crucial epitopes recognized by microfilaremic (MF) sera with significantly high IgG4 isotype (p < 0.001), implicated in immunomodulation. The epitope peptides identified were highly specific for MF sera and, thus, have the potential to be exploited as diagnostic markers.

Vector transmission heterogeneity and the population dynamics and control of lymphatic filariasis.

A long-standing gap in lymphatic filariasis epidemiology is quantifying the potential effect that heterogeneous infection processes occurring in the major mosquito vector genera may have on parasite transmission and control. Although previous studies have focussed on examining the forms of the density dependent mechanisms regulating larval infection in various mosquito genera, there has been little work done thus far in investigating how such differential processes might interact with density-dependent processes occurring in other stages of the parasite life cycle to influence overall transmission dynamics between areas exposed to different transmitting vector populations. Here, we explore the impact that differences in vector genus-related larval infection dynamics may have on filariasis transmission and control using newly derived parasite transmission models incorporating the forms of the density-dependent processes regulating larval infection in the two major vectors transmitting filariasis, viz. culicine and anopheline mosquitoes. The key finding in this work is that filarial infection thresholds, system resilience, transmission dynamics and parasite response to control efforts, can all be influenced by the prevailing transmitting mosquito genus. In particular, we show that infection thresholds may be raised, system resilience to perturbations lowered and effects of repeated mass treatments in eliminating infection enhanced in anopheline filariasis compared to culicine filariasis, as a direct result of the occurrence and action of multiple positive density-dependent mechanisms influencing infection in this vector-parasite system, such as the "facilitation" function regulating larval infection dynamics in the vector and the inverse probability function governing adult worm mating in the host. These findings indicate that anopheline filariasis may be easier to eradicate than culicine filariasis for a given precontrol infection level, although the actual intensity of interventions required to achieve eradication may in fact be similar to that for culicine filariasis because of the higher infection levels generated as a result of the "facilitation" process in Anopheles transmission areas.

Microfilariae in lymph node aspirate associated with metastatic gastric carcinoma: a case report.

BACKGROUND: Microfilariae of Wuchereria bancrofti inhabit peripheral blood, and nocturnal periodicity is observed in the Indian subcontinent. However, microfilariae have been reported in various tissues and organs by needle aspiration cytology in atypical cases. Occasionally, they were detected in cases with some diseases including malignancy. CASE: A 55-year-old man presented with complaints of weakness, abdominal distention and anorexia for 3 months. He had pain in the upper abdomen, passage of blackish stool and an episode of hemoptysis later on. A provisional diagnosis of gastric carcinoma with cirrhosis and ascites was made. Aspiration cytology of the left supraclavicular lymph node revealed a microfilaria in the background of malignant cells. Biopsy of the antral mass confirmed the diagnosis of gastric carcinoma. CONCLUSION: Detection of a microfilaria with malignant cells in the lymph node aspirates in a case of gastric carcinoma as an incidental finding is being reported for the first time. It may be due to its transmigration along with metastatic emboli in an immunosuppressed state.

Ecological meta-analysis of density-dependent processes in the transmission of lymphatic filariasis: survival of infected vectors.

The survival rate of infected vectors represents one of the fundamental components that influence the transmission dynamics of mosquito-borne diseases. Despite the occurrence of a number of studies investigating mosquito survival after infection with filarial worms, there remains conflicting evidence from both laboratory and field experiments as to the existence and mechanism for parasite-induced mortality among filarial mosquitoes. Here, we used a mixed effects meta-analytical framework to combine the data from all available vector-human host blood feeding experiments to evaluate the evidence for the impact of parasite load on the mortality rates of the three major lymphatic filariasis transmitting mosquito genera, Culex, Aedes, and Anopheles mosquitoes, over the extrinsic incubation period of parasitic infection. The results show that, despite the application of this approach, or in the case of Anopheles using a convention fixed effects logistic regression analysis supplemented with additional survival analysis of longitudinal data, no strong association between mortality rate and microfilariae (mf) uptake for either of the three mosquito genera is apparent in the combined data. Instead, a key finding is that study effects played a more crucial role in determining the levels of mortality observed in these experimental studies. This was most revealing in the case of Culex, given that the largest single study in terms of both the number of data points and range of mf intensities, in contrast to smaller studies, showed a significant positive association between mf intensity and mortality, indicating that in this genus at least, the detrimental effect of infection may be manifested only at the highest mf intakes. Although no density dependence in vector mortality was also observed for Aedes, possibly because of the use of restricted human mf intensity range in previous studies, an intriguing finding was that a significantly higher overall mortality was observed for this genus over mfintake ranges that produced much less corresponding mortality in Culex and Anopheles. The results also indicate that currently very little can be said about the survival rate of Anopheles mosquitoes infected with filarial worms because of the striking paucity of data for this genus. Further studies, using standardized methods and covering an appropriate range of mf uptake intensities and using study frameworks that allow the design and comparison of data from both experimental and field experiments, are clearly indicated if we are to reliably quantify the likely effect of filarial infection on vector survival.

Expression of defensin, cecropin, and transferrin in Aedes aegypti (Diptera: Culicidae) infected with Wuchereria bancrofti (Spirurida: Onchocercidae), and the abnormal development of nematodes in the mosquito.

The temporal expression of defensin, cecropin and transferrin was assessed in Aedes aegypti naturally refractory to Wuchereria bancrofti upon infection with this worm, in parallel to analysis of filarial development in the insect. Compared to controls, transcription of defensin and cecropin was higher in infected mosquitoes as soon as 2h post infection and peaked before 48h. Transferrin transcription was higher in infected mosquitoes at 24h, and at 48h was almost leveled to controls. At 72h and 7 days post infection, levels of all transcripts in infected insects decreased gradually and were similar to controls in most cases. Worm development in A. aegypti was visually abnormal from the beginning of infection. Here, we report, for the first time, the up-regulation of endogenous immune molecules in A. aegypti infected with W. bancrofti and provide a description of the worm development inside the insect. The specificities of A. aegypti-W. bancrofti model compared to other mosquito-filaria systems are discussed.

Plasma vascular endothelial growth Factor-A (VEGF-A) and VEGF-A gene polymorphism are associated with hydrocele development in lymphatic filariasis.

Hydrocele is a build-up of fluid in the scrotal regions of a proportion of men infected with the filarial nematode Wuchereria bancrofti. Vascular endothelial growth factors (VEGF) are major mediators of vascular permeability and angiogenesis in the development and progression of many diseases, making them candidates in hydrocele development. We assessed the role of VEGF-A genetic polymorphisms in hydrocele development in a cohort of lymphatic filariasis patients from Ghana. Three VEGF-A promoter polymorphisms were examined. The C/C genotype at -460 was significantly higher in hydrocele patients ([P = 0.0007], OR = 3.8 [95% CI = 1.9-8.2]) than in non-hydrocele patients. Furthermore, plasma levels of VEGF-A were significantly higher in subjects with the C/C genotype than in those with other genotypes. Also, a positive correlation (R(2) = 0.412, P = 0.026) was observed between plasma VEGF-A and stage of hydrocele. The data suggest that the C polymorphism at -460 is a genetic risk factor for hydrocele development in lymphatic filariasis.