Wuchereria bancrofti

Wolbachia are symbiotic endobacteria that infect the majority of filarial nematodes, including Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus. Recent studies have suggested that Wolbachia are necessary for the reproduction and survival of filarial nematodes and have highlighted the use of antibiotic therapy such as tetracycline/doxycycline as a novel method of treatment for infections caused by these organisms. Before such therapy is conceived and implemented on a large scale, it is necessary to assess the prevalence of the endosymbiont in W. bancrofti from different geographical locations. We present data from molecular and electron microscopic studies to provide evidence for Wolbachia symbiosis in W. bancrofti microfilariae collected from two districts (Bankura and Birbhum) of West Bengal, India.

Entomological investigations were conducted in four remaining lymphatic filariasis endemic provinces of Panay Island, The Philippines to determine mosquito species present in these areas and to identify host preference and biting activity of Aedes (Finlaya) poicilius Theobald, primary vector of nocturnal periodic Wuchereria bancrofti in The Philippines. Sampling techniques targeted nocturnally active mosquito species using a carabao-baited trap (CBT) and human-landing collection (HLC), the latter taking place from 06:00 to 12:00 pm. A total of 25,536 mosquitoes comprising 42 species and 7 genera were collected from CBT, whilst HLC acquired 6,486 mosquitoes comprising 28 species and 5 genera. Three known or potential vectors of human filarial were collected, namely, Aedes poicilius, Culex quinquefasciatus and Mansonia uniformis. The peak landing (biting) activity for Ae. poicilius was between 09:00 and 11:00 pm. Comparisons between CBT and HLC yields showed this species to be more zo...

Background and Aim: Lymphatic filariasis, also known as elephantiasis, still remains a problem in Indonesia. The primary causative species of this disease are the filarial worms Wuchereria bancrofti and Brugia spp. This study was conducted to identify the diversity of species and behavior of mosquitoes and to determine the mosquitoes that could be potential vectors of filariasis.

Materials and Methods: Mosquito samples derived from Hulu Sungai Utara (HSU) district in the 2017 multicenter study conducted in Indonesia were used in this cross-sectional study. The diversity of mosquito species was analyzed using the Shannon–Wiener diversity index. Mosquitoes were identified based on their species, and their DNA was isolated by polymerase chain reaction (PCR). Transcription-insulated isothermal PCR method was used to detect microfilariae/filaria larvae in the mosquitoes.

Results: Biodiversity was found in 14 species of mosquitoes belonging to five genera. The maximum number of mosquitoes was recorded from the species Mansonia dives, Culex vishnui, Culex quinquefasciatus, and Mansonia uniformis. W. bancrofti infection was detected in M. uniformis at an infectivity rate of 0.3% (n=311).

Conclusion: To the best of our knowledge, this is the first report of M. uniformis species as a vector of W. bancrofti in HSU district, Indonesia. More efficient and accurate studies are required to aid in the lymphatic filariasis elimination programs in this subregion.

The monitoring and evaluation of lymphatic filariasis (LF) has largely relied on the detection of antigenemia and antibodies in human populations. Molecular xenomonitoring (MX), the detection of parasite DNA/RNA in mosquitoes, may be an effective complementary method, particularly for detecting signals in low-level prevalence areas where Culex is the primary mosquito vector. This paper investigated the application of a household-based sampling method for MX in Tamil Nadu, India. MX surveys were conducted in 2010 in two evaluation units (EUs): 1) a hotspot area, defined as sites with community microfilaria prevalence ≥1%, and 2) a larger area that also encompassed the hotspots. Households were systematically selected using a sampling interval proportional to the number of households in the EU. Mosquito pools were collected and analyzed by real-time polymerase chain reaction (qPCR). Two independent samples were taken in each EU to assess reproducibility of results. Follow-up surveys w...

The objective of this study was to develop a site directed geographic information system (GIS) map of lymphatic filariasis (LF) in Gampaha District, Sri Lanka as a guide for targeted control activities. Epidemiological and entomological screening of LF was carried out in nine pre-identified endemic areas in Gampaha District, using night blood screening and pool-screening PCR-ELISA. In total, 1,073 subjects (286 children, 787 adults) from 9 sites were examined. Positive cases were detected at 2 sites, with prevalence rates of 0.5% (Hekiththa) and 3.4% (Peliyagoda); the prevalence of microfilaria (mf) among adult Culex quinquefasciatus mosquitoes surveyed was 30%. The overall prevalence of mosquitoes with L1-L2 larvae of W. bancrofti ranged from 0% to 8.31% using dissection and point estimates of infection prevalence, and ranged from 0 to 32.4% using PCR-ELISA. The largest number of human cases was found at altitudes of 2.5-3.5 min highly populated areas, where transmission appears to...

The Global Program to Eliminate Lymphatic Filariasis has been implemented to reduce human microfilaremia to levels low enough to break the transmission of the disease by using single annual doses of albendazole in combination with diethylcarbamazine or ivermectin. Many veterinary helminth parasites have developed resistance against both albendazole and ivermectin. Resistance to albendazole in veterinary nematodes is known to be caused by either of two single amino acid substitutions from phenylalanine to tyrosine in parasite beta-tubulin at position 167 or 200. We have developed assays capable of detecting these single nucleotide polymorphisms (SNPs) in Wuchereria bancrofti, and have applied them to microfilaria obtained from patients in Ghana and Burkina Faso. One of the SNPs was found in worms from untreated populations in both locations. Worms from treated patients had significantly higher frequencies of these mutations. These findings indicate that a beta-tubulin allele associat...

Wuchereria bancrofti is also known as Bancroft's filarial, and the diseases and conditions associated with it are known as Bancroft's filariasis or elephantiasis. Wuchereria bancrofti is thought to have originated in the second millennium BC. This parasite appears to have spread over time as people traveled around the world exploring and relocating. When early explorers visited Polynesia in the 17th and 18th centuries, they learned about bancroftian filariasias. In Charleston, South Carolina, an epidemic caused by Wuchereria bancrofti died out around 1930. The infection is thought to have been brought to the United States by African slaves sent to Charleston. Morphology of Wuchereria bancrofti Microfilariae. The average microfilaria is 240 to 300 m long, with a thin and delicate sheath surrounding the organism. The body contains numerous nuclei. The cephalic or anterior end is blunt and round. The posterior or tail end culminates in a point devoid of nuclei. This is an important feature that distinguishes it from other sheathed microfilariae. Adults Wuchereria bancrofti Adult Wuchereria bancrofti worms are white and thread-like in appearance. Females are typically larger than males, measuring 40 to 100 mm versus 20 to 40 mm. Epidemiology of Wuchereria bancrofti W. bancrofti can be found in both subtropical and tropical climates. In the Eastern Hemisphere,

A pilot study of lymphatic filariasis was conducted in two contiguous villages of Patna district in Bihar situated at the side of the river Ganges, known to be endemic for lymphatic filariasis, to study present status of transmission parameters of filariasis. Of the 1872 persons examined, 8.4% were found asymptomatic but microfilaraemic. Morbidity pattern due to filarial infection showed an increase with advancement of age and significantly high in males as compared to female (p < 0.001). Acute and chronic filarial disease was observed as 0.5% and 9% respectively. Microfilaria was found in 10% of acute and 11.2% of chronic filarial cases. The Mf rate was found to be 9.9% in males and 9.0% in females respectively. The parasite species was identified as W. bancrofti. The vector fauna surveyed show highest prevalence of vector species of Cx. quinquefasciatus (43%) in both domestic as well as predomestic area in the community. Other species like Cx. vishnui and Ma. uniformis were als...

Entomological investigations were conducted in four remaining lymphatic filariasis endemic provinces of Panay Island, The Philippines to determine mosquito species present in these areas and to identify host preference and biting activity of Aedes (Finlaya) poicilius Theobald, primary vector of nocturnal periodic Wuchereria bancrofti in The Philippines. Sampling techniques targeted nocturnally active mosquito species using a carabao-baited trap (CBT) and human-landing collection (HLC), the latter taking place from 06:00 to 12:00 pm. A total of 25,536 mosquitoes comprising 42 species and 7 genera were collected from CBT, whilst HLC acquired 6,486 mosquitoes comprising 28 species and 5 genera. Three known or potential vectors of human filarial were collected, namely, Aedes poicilius, Culex quinquefasciatus and Mansonia uniformis. The peak landing (biting) activity for Ae. poicilius was between 09:00 and 11:00 pm. Comparisons between CBT and HLC yields showed this species to be more zo...

Wolbachia are intracellular α-proteobacteria, closely related to Rickettsia, that infect various arthropods and filarial parasites. In the present study, the cDNA encoding the aspartate aminotransferase (AspAT) of Wolbachia from the human pathogenic filarial parasite Onchocerca volvulus (Ov-WolAspAT) was identified. At the amino acid level, the identity of the Ov-WolAspAT was 56% to Rickettsia prowazekii AspAT and 54% to the AspAT of the nitrogen-fixing bacterium Sinorhizobium meliloti, but the highest degree of identity was found to the putative AspAT of Wolbachia from Brugia malayi and Drosophila melanogaster (85%). All of these bacterial AspATs are members of the AspAT subclass Ib. A 35 kDa fragment of the Ov-WolAspAT was expressed in Escherichia coli, and immunolocalization using polyclonal antibodies against this antigen revealed that Ov-WolAspAT is present in a considerable proportion of the Wolbachia from O. volvulus, as well as in the endobacteria of several other filarial parasites. Western blot analysis using recombinant Ov-WolAspAT as antigen showed that IgG1 antibodies were present in 70 (51%) individuals living in areas endemic for O. volvulus, B. malayi or Wuchereria bancrofti and no IgG4 or IgE antibodies were found. Among 40 sera of persons from Uganda and Liberia who were putatively not infected with human filarial parasites, 11 (28%) individuals presented IgG1 antibodies, while none of the 33 sera from healthy Europeans and none of the 14 sera from patients with proven Rickettsia or Brucella infections reacted with the antigen. These results also show that an intracellular protein of Wolbachia endobacteria (WolAspAT) acts as antigen in human filariasis.

Background Recent data from Ghana indicates that after seven rounds of annual mass drug administration (MDA) there is still sustained transmission albeit at low levels in certain areas where Anopheles melas, An. gambiae s.s., Mansonia and Culex species are the main biting mosquitoes. Anopheles gambiae s.l. and An. funestus are the known vectors in Ghana and a recent report indicated that An. melas could transmit at low level microfilaraemia. However, because An. melas is not found everywhere there was the need to determine whether any of the other culicine species could also be playing a role in the transmission of LF. Methods Indoor mosquitoes collected once a month for three months using pyrethrum spray catches in six communities within the Kommenda-Edina-Eguafo-Abirem (KEEA) District, Central Region of Ghana were morphologically identified, dissected and examined for the presence of W. bancrofti. Additionally, stored mosquito samples collected during previous years in 8 communiti...

Entomological investigations were conducted in four remaining lymphatic filariasis endemic provinces of Panay Island, The Philippines to determine mosquito species present in these areas and to identify host preference and biting activity of Aedes (Finlaya) poicilius Theobald, primary vector of nocturnal periodic Wuchereria bancrofti in The Philippines. Sampling techniques targeted nocturnally active mosquito species using a carabao-baited trap (CBT) and human-landing collection (HLC), the latter taking place from 06:00 to 12:00 pm. A total of 25,536 mosquitoes comprising 42 species and 7 genera were collected from CBT, whilst HLC acquired 6,486 mosquitoes comprising 28 species and 5 genera. Three known or potential vectors of human filarial were collected, namely, Aedes poicilius, Culex quinquefasciatus and Mansonia uniformis. The peak landing (biting) activity for Ae. poicilius was between 09:00 and 11:00 pm. Comparisons between CBT and HLC yields showed this species to be more zo...

Few studies have documented the interruption of onchocerciasis and Lymphatic Filariasis (LF) by integrated chemotherapy in Uganda. The study describes the interruption of transmission of the two diseases co-endemic in Obongi focus, north western Uganda. Base line data for Onchocerciasis and LF were collected in 1994 and 2006, respectively. Annual mass drug administration for onchocerciasis (Ivermectin) and Lymphatic Filariasis (Ivermectin + albendazole) was conducted for 20 and 6 years, respectively. Thereafter, assessments by skin snip, larval searches in rivers and human landing catches were performed. Children <10 years were screened for IgG4 antibodies using Ov16 ELISA technique in 2013. LF Pre-TAS and TAS1 were conducted in sentinel sites. ITN coverage and utilization for the implementation unit was also reported. Onchocerciasis treatment coverage was <80% but improved with the introduction of CDTI in 1999. While for LF, effective coverage of >65% was achieved in the s...

Lymphatic filariasis (LF) is a chronic nematode infection transmitted by mosquitoes and in sub-Saharan Africa it is caused by Wuchereria bancrofti. The disease was targeted for global elimination by 2020 using repeated community-wide mass drug administration (MDA) distributed in endemic areas. However, recently, there has been a growing recognition of the potential role of including vector control as a supplement to MDA to achieve elimination goal. This study was carried out to determine mosquito abundance and transmission of bancroftian filariasis on Mafia Islands in Tanzania as a prerequisite for a search for appropriate vector control methods to complement the ongoing MDA campaign. Mosquitoes were collected indoor and outdoor using Centre for Disease Control (CDC) light and gravid traps, respectively. Collected mosquitoes were identified based on their differential morphological features and Anopheles gambiae complex and An. funestus group were further identified to their respect...

In the present study we examined the utility of measuring antigen-specific soluble immune complexes (ICs) for the differential diagnosis and therapeutic monitoring of Bancroftian filariasis. Antigen-specific ICs were detected in significantly elevated levels in 90% of lymphatic filarial subjects suffering from disease manifestations, and very low levels in 8–10% of microfilaria (MF) carriers. The high incidence of antigen-specific ICs in the circulation of filarial subjects with clinical manifestations in contrast to the negligible presence in MF carriers facilitates serological differentiation of these two important stages of lymphatic filarial infection. A sudden spurt in circulating levels of antigen-specific ICs was recorded in all MF carriers on diethylcarbamazine (DEC) therapy, and the magnitude of the increase correlated positively with the pretreatment levels of circulating MF. Thus, it is evident from the present study that circulating ICs (CICs) are potential serological markers for both the differential diagnosis of filarial infection and therapeutic monitoring of MF carriers. J. Clin. Lab. Anal. 21:114–118, 2007. © 2007 Wiley-Liss, Inc.

Background The epidemiological knowledge on acute condition of lymphatic filariasis is essential to understand the burden and issues on management of the disease. Methods A one year long longitudinal prospective surveillance of acute adenolymphangitis (ADL) was carried out in rural population of Orissa, India. Results The annual incidence of ADL per 1000 individuals is 85.0, and is slightly higher (P > 0.05) in male (92.0) than in female (77.6). A steady rise in the incidence of ADL episodes along with the age is recorded. The distribution indicates that persons with chronic disease are more prone to ADL attacks. The average number of episodes per year is 1.57 (1.15 SD) per affected person, and is gender dependent. Duration of the episode varies from 1 to 11 days with mean duration of 3.93 (1.94 SD) days. The chronic disease is the significant predictor for the duration of the episode. The data show that fever and swelling at inguinal regions are most common symptoms. Conclusion The incidence, frequency and duration of ADL episodes in this community are similar to that of other endemic areas. As the loss due to these ADL episodes is substantial, it should be considered while further estimating the burden due to lymphatic filariasis. The disability and loss caused by chronic forms of filariasis is higher, and the additional incapacity caused by the ADL episode, majority of which occur among chronic filariasis patients, further poses the burden on individuals and their families. Hence, morbidity management measures to prevent ADL episodes among endemic communities are to be implemented.

Lymphatic filariasis is a vector-borne health problem that has been focally endemic in Egypt for centuries. The chief vectors of transmission are Culicinae species. Control measures in the form of mass drug administration of DEC citrate treatment have been implemented in Nile delta for almost a decade. This study aimed to identify the prevalent mosquito species in endemic areas in Giza and Qualioubiya governorates and to monitor Wuchereria bancrofti infection by detecting the parasite DNA in collected mosquitoes. Adult mosquitoes were collected using light traps hung indoors. Microscopic examination was performed to identify and examine the morphologic characters of mosquitoes. Female Culex mosquitoes were subjected to semi-nested PCR to detect filarial DNA targeting repetitive DNA sequences (pWbl2 repetitive region) specific for W. bancrofti. The results revealed 3 species of mosquitoes Culex pipiens, Culex pusillus and Culex quinquefasciatus with the predominance of Culex pipiens ...

To determine whether albumin is present on adult worms of Wuchereria bancrofti, thin sections of resin-embedded parasites were incubated with a specific antiserum to human albumin. With the exception of the epicuticle, all layers of the cuticle and the ...

Growing evidence suggest that secondary bacterial, mainly streptococcal, infections contribute significantly to recurrent episodes of acute adenolymphangitis (ADL) of filarial origin. We examined the role of group A streptococci in the progression of lymphedema in Polynesian patients with filariasis-related ADL (22 cases) or chronic pathology (10 cases), or with erysipela (10 patients) and, as controls, in 20 healthy adults. Antistreptolysin O (ASLO) and anti-streptodornase B (ASDB) titers were systematically determined in parallel to parasitological and biochemical tests. ASLO and ASDB assays were positive in 100% of erysipela, 75% of filarial ADL as compared to 50% of chronic pathology and 39% of healthy controls. Interestingly, by opposition to ASLO titers which were not significantly different between the four groups, ASDB titers were higher in ADL (p = 0.019) and erysipela (p = 0.002) than in controls. These results support the hypothesis that recurrent streptococcal infections...

A loop-mediated isothermal amplification (LAMP) assay was developed for the diagnosis of Theileria lestoquardi infection. The primers were designed based on the clone-5 sequence of T. lestoquardi. The specificity and sensitivity of the assay were established. Analysis of the specificity showed that the selected LAMP primers amplified the target sequence from T. lestoquardi DNA successfully, while no amplification was seen with DNA from Theileria annulata, Theileria ovis, Babesia ovis, Anaplasma ovis, or ovine genomic DNA. The specificity of the LAMP product was further confirmed by restriction digestion and sequencing. The sensitivity of the LAMP assay was analyzed in comparison to PCR resulting in a detection limit of 10 fg/μl of plasmid DNA containing the clone-5 sequence. The suitability for utilizing the LAMP assay in the field for the diagnosis of T. lestoquardi infection was tested on 100 field samples collected in Sudan and compared with results obtained by PCR. The relative specificity and sensitivity of the established LAMP assay was determined to be 92.1% and 87.5%, respectively, indicating that it may be regarded as an alternative molecular diagnostic tool to PCR which could be used for epidemiological surveys on T. lestoquardi infection.

The specific laboratory diagnosis of filariasis depends either on the demonstration of circulating microfilaria in the peripheral blood or various stages of the parasite in tissue sections. Various morphological characteristics of the parasite will normally assist in its identification to the genus and specific level. Concentration techniques, especially those using the polycarbonate membrane filtration of a ml or more of heparinised blood, can detect the parasite in those with very low microfilaria counts. Serological techniques using the indirect fluorescent assay with microfilaria and adult worm antigens can assist in confirming a clinical suspicion of filaria infection when the parasite is not demonstrable. The development and use of specific monoclonal antibodies for the detection of circulating antigens in the enzyme-linked immunosorbent assay will probably increase the specificity of the assay. Presently available specific DNA probes for filariasis are probably not as useful ...

Entomological investigations were conducted in four remaining lymphatic filariasis endemic provinces of Panay Island, The Philippines to determine mosquito species present in these areas and to identify host preference and biting activity of Aedes (Finlaya) poicilius Theobald, primary vector of nocturnal periodic Wuchereria bancrofti in The Philippines. Sampling techniques targeted nocturnally active mosquito species using a carabao-baited trap (CBT) and human-landing collection (HLC), the latter taking place from 06:00 to 12:00 pm. A total of 25,536 mosquitoes comprising 42 species and 7 genera were collected from CBT, whilst HLC acquired 6,486 mosquitoes comprising 28 species and 5 genera. Three known or potential vectors of human filarial were collected, namely, Aedes poicilius, Culex quinquefasciatus and Mansonia uniformis. The peak landing (biting) activity for Ae. poicilius was between 09:00 and 11:00 pm. Comparisons between CBT and HLC yields showed this species to be more zo...

To assess the clinical findings associated with detection of adult Wuchereria bancrofti worms on ultrasound, 186 schoolchildren in a filariasis-endemic area of Haiti underwent physical and ultrasonographic examinations. The filaria dance sign (FDS) of adult W. bancrofti was detected in the inguinal and crural lymphatics of 28 (15%) children. FDS detection was more common in older children (P = 0.003) and in those with a history of inguinal lymph node inflammation (P = 0.002) or crural lymphadenopathy on physical exam (P = 0.01). Twenty-five FDS-positive children were reexamined after three annual cycles of mass treatment for lymphatic filariasis (LF). The total number of adult worm nests detected by ultrasound decreased from 29 to 4 (P </=0.0001). FDS and lymphangiectasia were detected in the intrascrotal (N = 3) and inguinal (N = 1) lymphatic vessels of three postpubescent boys. This study demonstrates clinical and subclinical findings of LF in FDS-positive children.