Filariasis Research Articles

Filarial parasite infection prevalence in field-caught mosquitoes from Connecticut, United States.

Filarial nematodes are parasitic roundworms transmitted by mosquitoes that can cause morbidity and mortality for their human and animal hosts. The filariae community, specifically infection prevalence of heartworm, Dirofilaria immitis (Filarioidea: Onchocercidae) (Leidy), and its primary mosquito vector species, has not been described in Connecticut since 1977. In light of the recent invasion and establishment of an important filariasis vector, Aedes albopictus (Diptera: Culicidae) (Skuse), we used molecular-based sequencing methods to identify filarial species infecting field-caught mosquitoes in Connecticut, United States. The filarial parasites identified include D. immitis, Aproctella sp., and Setaria sp. (Filarioidea: Setariidae). The total minimum infection rate for D. immitis for all mosquito species tested in 2020 was 0.97 [0.56 to 1.56] and in 2021 was 1.48 [0.93 to 2.24]. Aedes albopictus had the highest infection prevalence compared to other species during both years. We determined a low but persistent mosquito infection prevalence for D. immitis and suggest that Ae. albopictus is likely to be the primary vector in the region. Aproctella sp. and Setaria sp. had lower burdens compared to D. immitis. Persistent mosquito infection with filarial parasites, particularly in invasive species, poses a risk to veterinary and public health.

Profiling the broad antibody diversity of lymphatic filariasis immune antibody repertoire by deep sequencing.

Lymphatic filariasis is caused by infections of thread-like filarial worms, namely Wuchereria bancrofti, Brugia Malayi and Brugia timori. However, in-depth analysis of the antibody repertoire against Lymphatic filariasis is lacking. Using high-throughput sequencing of antibody repertoires, immunome analysis of IgG (LG) and IgM (LM) repertoires were studied. Despite significant differences between LG and LM in V(D)J gene usage, IGHV4-34, IGHV6-1, IGHD3-10 and IGHJ4 were preferred in both repertoires. The CDR3 in the LG repertoire showed a longer length than LM. Higher SHM level were observed in LG sequences and presence of oligoclonal sequences indicates the extent of clonal expansion. The prevalence of rare clonotypes in LM repertoire depicts the high clonal diversity when compared to LG repertoire. Monoclonal antibodies against closely related parasitic infections were present within the LG repertoire suggesting that immune repertoires may not be as exclusive and biased against the target infection as initially thought. The characterization of the immune repertoire can provide critical insight into the antibody response patterns in disease state, antibody generation process during infections and future antibody designs.

Molecular detection of parasites and host preference in wild-caught Culicoides biting midges (Diptera: Ceratopogonidae) in Chiang Mai and Nakhon Si Thammarat Provinces, Thailand.

Culicoides biting midges (Diptera: Ceratopogonidae) have been reported as potential vectors for haemoparasites. Information about host-vector-parasite specificity is required to confirm their status. Here, molecular detection of haemosporidians, Leishmania, trypanosomatids, and filarial nematodes in biting midges was conducted to understand their potential role as vectors, and their host preference was determined. Wild-caught biting midges were collected from six different localities of Chiang Mai and Nakhon Si Thammarat provinces, Thailand. A total of 6,578 individual Culicoides (170 males, 6,408 females) comprising 15 species of six sub-genera and two groups were collected. Also, 738 parous females and 29 engorged females were examined for parasites and host blood meals, respectively. Culicoides arakawae, C. mahasarakhamense, C. peregrinus and C. innoxius in Chiang Mai province, and C. innoxius and C. peregrinus in Nakhon Si Thammarat province were the most dominant species. Leucocytozoon spp., Leucocytozoon caulleryi and Plasmodium juxtanucleare were identified in five Culicoides species including C. mahasarakhamense, C. arakawae, C. oxystoma, C. fulvus, and C. guttifer. This study is the first record of L. caulleryi in the biting midge C. arakawae in Thailand. Blood meal analysis revealed that Culicoides primarily fed on cattle (17/29, 58.6%), followed by chickens (10/29, 34.5%), and humans (2/29, 6.9%). Our findings confirmed the existence of several Culicoides species in Thailand, which might be potential vectors for transmission of haemosporidians (Leucocytozoon and Plasmodium). Information from host blood meal analyses underlined their preference for large mammals, followed by domestic chickens. More anthropophilic Culicoides species remain to be discovered.

Litomosoides sigmodontis microfilariae-induced eosinophil ETosis is dependent on the canonical inflammasome pathway.

Granulocytes exert several effector mechanisms, including the release of DNA traps during ETosis. While bacteria-induced ETosis has been linked to the non-canonical inflammasome pathway, the role of the inflammasome activation during ETosis in response to extracellular pathogens has not been investigated. The current study demonstrates that microfilariae (MF) of the rodent filarial nematode Litomosoides sigmodontis induce eosinophil ETosis via the canonical inflammasome pathway. The absence of key components of the canonical inflammasome, including gasdermin D, caspase-1, the adaptor molecule ASC, or AIM2 (double-stranded DNA sensor) prevents MF-induced DNA release in murine eosinophils. While AIM2 activation is not affecting other effector mechanisms such as reactive oxygen species generation and nuclear membrane collapse, it appears to be critical in mediating the release of DNA from the cell during the later stages of ETosis. Finally, the findings on inflammasome-dependent ETosis in response to MF are confirmed in human eosinophils.

Integrating post-validation surveillance of lymphatic filariasis with the WHO STEPwise approach to non-communicable disease risk factor surveillance in Niue, a study protocol.

Lymphatic filariasis (LF), a mosquito-borne parasitic disease caused by three species of filarial worms, was first detected in Niue, a small Pacific Island nation of approximately 1,600 people, in 1954. After extensive efforts involving multiple rounds of Mass Drug Administration, Niue was validated by the World Health Organization (WHO) as having e4liminated LF as a public health problem in 2016. However, no surveillance has been conducted since validation to confirm infection rates have remained below WHO's elimination threshold. WHO has encouraged an integrated approach to disease surveillance and integrating LF post-validation surveillance (PVS) with existing surveys is an anticipated recommendation of the upcoming WHO LF-PVS guidelines. This paper describes a protocol for the implementation of an integrated approach to LF-PVS in Niue as cost-efficient and operationally feasible means of monitoring the disease in the population. The LF-PVS will be implemented as part of a planned national population-based WHO STEPwise approach to non-communicable disease (NCD) risk factor surveillance (STEPS) in Niue. Integration between the LF-PVS and STEPS will occur at multiple points, including during pre-survey community awareness raising and engagement, when obtaining informed consent, during the collection of demographics, risk factor, and location data, and when collecting finger-prick blood samples (for glucose as part of the STEPS survey and LF as part of the LF-PVS). The primary outcome measure for LF transmission will be antigen positivity. Microfilaria slides will be prepared for any antigen-positive cases. Dried blood spots will be prepared for all participants for Multiplex Bead Assays-based analysis to detect anti-filarial antibodies. We estimate a total sample size of 1,062 participants aged 15-69, representing approximately 66% of the population. The results of this study will provide insight into the status of LF in Niue and evaluate the advantages, challenges, and opportunities offered by integrated approaches to disease surveillance.

Asymptomatic Malaria Infection and Hidden Parasitic Burden in Gabonese Schoolchildren: Unveiling Silent Co-Infections in Rural and Urban Settings.

This study aimed to determine the prevalence of co-infection with malaria and intestinal parasites and assess its association with anemia in school-aged children from rural and urban settlements in Gabon. This cross-sectional study involved afebrile school children recruited at schools between May and June 2021. Blood and stool samples were collected from participants whose parents or legal guardians provided informed consent to participate in the study. Hemoglobin concentration (Hb) was measured using a HemoCue photometer (HemoCue 201, HemoCue, Angelholm, Sweden). Giemsa-stained blood films were examined to detect malaria parasites and any filarial infections, while the merthiolate-iodine concentration (MIC) method was used to identify intestinal parasitic infections (IPI). A total of four hundred and seventy (470) school-aged children were successfully enrolled in this study. The observed prevalence values were as follows: malaria infection at 69.6%, IPIs at 19.1%, filaria at 5.1%, Schistosoma infection at 15.0%, and anemia at 29.0%. Co-infections of malaria with IPIs, filaria, and Schistosoma were present in 12.3%, 4.7%, and 6.6% of the children, respectively. Malaria and filaria infections were associated with residing in Lastourville city (p < 0.05) and were also correlated with age (p < 0.05), whereas IPIs were associated with male gender and living in the city of Lastourville. Anemia was linked to malaria infection (p < 0.05) and was more prevalent among children living in rural areas. The findings of this study indicate that malaria, IPIs, and Schistosoma infections continue to pose a significant public health problem in the study area, even though only malaria infection appeared to be associated with anemia. Nevertheless, these results highlight the need for implementing control measures to reduce the prevalence of malaria, IPIs, filaria, and Schistosoma, particularly in Lastourville.

First record of Culex pipiens (Diptera: Culicidae) in Alberta: expanding distributions and ecotype patterns in a western Canadian province.

Culex pipiens is an invasive mosquito found in temperate regions globally. It is considered among the most important disease vectors worldwide and is responsible for the transmission of a range of pathogens, including West Nile virus, avian malaria, Saint Louis encephalitis, and filarial worms. Throughout its northern temperate range, this mosquito is found in 2 ecotypes: form pipiens and form molestus. In Canada, this mosquito was previously thought restricted to the Pacific coast of British Columbia and the eastern provinces of Ontario, Quebec, and the Maritimes. Through routine mosquito surveillance and targeted trapping for Cx. pipiens, we detected this mosquito in 2 Albertan municipalities earlier than suggested by species distribution modeling based on climate change data. We confirmed the identity of putative Cx. pipiens specimens using DNA sequencing and found that alleles associated with form molestus were present, but at a low frequency compared to alleles associated with form pipiens. Furthermore, we compared the frequency of ecotype-related alleles in Alberta to elsewhere in North America and found a general trend of increased form pipiens in more northern latitudes, similar to previously reported results. We discuss our findings in the context of vector-borne disease activity in Canada, particularly West Nile virus.

Large-scale production of Mansonella perstans infective larvae from engorged Culicoides milnei.

Mansonella perstans is transmitted by Culicoides species and affects hundred millions of inhabitants in about 33 countries in sub-Saharan Africa. It is known that Mansonellosis due to Mansonella perstans do not result in a clear clinical picture, but down-regulates the immunity of patients predisposing them to other diseases like tuberculosis, HIV and malaria or damping vaccine efficacy. However, research about novel drugs against this filarial nematode is missing because of the lack of parasite material. Previous studies have developed in vitro culture systems using infective stage 3 larvae (L3), but these life stages are difficult to obtain and thus the performance of in vitro cultures is restricted and does not allow large-scale testing of drugs or even infection experiments in animal models. Therefore, we aim to establish a platform for the large-scale production of M. perstans infective larvae from engorged Culicoides milnei. Culicoides species were caught in Yangom (Yabassi Health District) in the Littoral Region of Cameroon following a blood meal on six microfilariae-positive donors with different microfilaraemic loads over one year. Engorged midges were reared in the insectarium for up to 14 days and L3 were isolated from the different body parts. In summary, 13,658 engorged Culicoides were collected and reared in the laboratory. We observed an overall predicted survival of 78.5%. Out of the 8,123 survived midges, 7,086 midges belong to C. milnei, from which 2,335 were infected leading to a recovery of 6,310 L3. Moreover, we found the highest survival rates of midges during the early dry season in December with moderate temperatures (23-25°C) and low (2-4mm) or no rainfall. In addition, we observed that midges that fed on donors with high microfilarial loads showed increased mortality. We revealed suitable conditions for the collection and maintenance of engorged Culicoides midges allowing the large-scale production of M. perstans L3. This procedure will provide a platform to produce sufficient parasite material that will facilitate in vitro cultures and the establishment of a murine model of M. perstans, which is important for in-depth investigation of the filarial biology and screening of novel drugs that are effective against this ivermectin-resistant nematode.

Confirming non-endemicity of podoconiosis in Guatemala and in Idukki District in Kerala (India): a comparison of two approaches potentially suitable for other neglected tropical diseases

BackgroundPodoconiosis is an underreported lymphoedema whose distribution is uncertain at global level and within endemic countries. Previous work has identified countries with historical evidence of podoconiosis, but which do not currently report cases. Podoconiosis may persist in these countries or have been eliminated due to socioeconomic development. Here we describe two different approaches used to clarify podoconiosis endemicity status in Guatemala and in Idukki District (Kerala State, India).MethodsTwo different epidemiological approaches were used by different research teams, determined by the available resources and contextual factors in the two settings. In Guatemala, where lymphoedema cases are routinely recorded in the health information system, 102 municipalities with suspected cases, historical evidence of podoconiosis, high poverty rates, or environmental suitability for the disease were visited. Active case searches were conducted from July 2016 to October 2018, and suspected cases were clinically examined to confirm or rule out podoconiosis. In Idukki, where lymphoedema cases were not routinely recorded, a population-based prevalence survey for lymphoedema was conducted from September to December 2022, covering 13,664 individuals aged 15 years and older.ResultsBoth approaches were effective at clarifying podoconiosis endemicity. In Guatemala, 20 cases with lower limb swelling were investigated. Podoconiosis was ruled out in all cases, and filarial lymphoedema was suspected in three. In Idukki District, 105 cases of lower limb swelling were identified. None was confirmed to have podoconiosis, with post-surgical lymphoedema and hypertension being the most common diagnoses. Active filarial infection was identified in two cases in Idukki District.ConclusionsThese investigations provide evidence that podoconiosis is currently non-endemic in Guatemala and in Idukki District in India. They also demonstrate that population-based surveys and targeted case searches both provide effective ways to explore disease endemicity in areas where this is uncertain. The most appropriate approach depends on a combination of contextual and research-based factors, including evidence for endemicity, resources available, and geographical, population, and health system factors.

Bat microfilariae in the cityscape: a transmission tale between bats, mites, and bat flies

Litomosoides includes filarial nematodes capable of infecting various vertebrate species. While Litomosoides has been extensively studied in rodents, research on its association with bats remains limited. The transmission dynamics of this parasite are complex, involving moving between different invertebrate hosts before reaching the final host. Most investigations concerning microfilariae have concentrated on their morphological characteristics, with scant attention paid to ecological aspects, particularly in human-altered landscapes. This study represents the first known documentation of Litomosoides in bats within an urban environment. It investigates their response to urbanization in their interaction with the synanthropic bat Artibeus jamaicensis and its ectoparasites. The objective was to explore the influence of urban landscapes on Litomosoides prevalence in synanthropic hosts. Blood samples were collected along urban–rural gradients, and parasite presence was confirmed through direct observation in blood smears and PCR. Phylogenetic analysis based on the mitochondrial cytochrome c oxidase subunit 1 gene (COX1), which exhibited robust support values, indicates that the microfilaria found in A. jamaicensis is closely related to Litomosoides chandleri. However, it also suggests the possibility of an unidentified, and therefore potentially new, species within the genus Litomosoides. Additionally, Litomosoides DNA was detected in Periglischrus iheringi (Acari: Spinturnicidae) and in the bat fly Trichobius intermedius collected from the bat. The parasite sequences obtained from these three interacting species exhibited a genetic distance as low as 0.002. The highest prevalences were recorded in forested areas (28.6%) compared with urban areas (21.2%). However, within the urban landscape, prevalence varied from 3.8% to 21.2%, being highest in densely built-up areas. Analysis of the urban landscape suggested that the prevalence of Litomosoides in A. jamaicensis is the result of a multifactorial and synergistic process involving ectoparasite load, host abundance, and the extent of impervious surfaces (NDBI).

A footworm in the door: revising Onchocerca phylogeny with previously unknown cryptic species in wild North American ungulates

Onchocerca is an important genus of vector-borne filarial nematodes that infect both humans and animals worldwide. Many Onchocerca spp., most of medical and veterinary health relevance, are the focus of a variety of diagnostic and molecular research. However, despite the importance of these parasites, there is growing evidence of previously unexplored genetic diversity of these nematodes, particularly among wild ungulate hosts in North America. These understudied parasites prevent us from comprehending the evolutionary history of the genus Onchocerca, monitoring potential One Health threats, and improving our filarioid diagnostic capabilities. In order to fill these knowledge gaps, we identified five uncharacterized Onchocerca lineages and compared them with other well-known filarioid species using single and concatenated gene regions (i.e., nd5, cox1, 12S, 18S, 28S, hsp70, MyoHC, rbp1). Phylogenetic analyses revealed that the novel Onchocerca lineages of wild North American ungulates segregate into two clades. One clade comprised Onchocerca lineages II, IV, and V and other species found mainly in domestic animals and humans, and the second comprised Onchocerca lineages I and III and other species from a variety of hosts including cervids, bovids, and equids. The formation of two clearly separate clades supports the idea of at least two independent expansion events of ancestral Onchocerca spp. into the North American continent via the Bering land bridge. Cophylogenetic analysis shows evidence of ancestral Onchocerca spp. of Bovidae host-switching to wild Cervidae and giving rise to the novel Onchocerca spp. Lastly, pairwise analysis confirms informative molecular markers of diagnostic relevance in both mitochondrial and nuclear gene regions of filarioid nematodes. The overall information provides greater context to the genus Onchocerca and emphasizes the need to discover, characterize, and monitor neglected parasites, especially those of wildlife origin.

Sequencing and Analysis of Wolbachia Strains from A and B Supergroups Detected in Sylvatic Mosquitoes from Brazil.

Wolbachia are endosymbiotic bacteria that infect a wide range of arthropods and filarial nematodes, often manipulating host reproduction. The efficacy of Wolbachia-based interventions for dengue and chikungunya control has been validated through numerous field studies in recent years. This study aimed to investigate the diversity and prevalence of Wolbachia infections in sylvatic mosquitoes from two locations in Recife, Brazil. Multiple mosquito species were screened for Wolbachia using both target marker gene amplification coupled with Sanger sequencing and whole-genome sequencing (WGS) approaches. Phylogenetic analyses were conducted to classify Wolbachia strains into supergroups and assess their evolutionary relationships. Results revealed the presence of Wolbachia in eleven mosquito species examined, with different infection rates. Both supergroups A and B of Wolbachia strains were identified, with Aedes albopictus showing co-infection by both supergroups through the WGS approach. We also detected indirect evidence of Wolbachia horizontal transmission among mosquitoes and other distant host orders. This study provides valuable insights into the distribution and diversity of Wolbachia in sylvatic mosquitoes from Brazil and adds new important data about Wolbachia detection through target marker gene amplicon coupled with Sanger sequencing and WGS methods, highlighting its complementarity to ascertain the presence of Wolbachia in mosquito samples.

Epidemiology of Mansonella perstans and Loa loa: Prevalence and Specific Risk Factors in Njombe-Penja Health District, Littoral Region of Cameroon

Aim: This epidemiological survey aimed to determine the prevalence and specific risk factors of Mansonella perstans and Loa loa infections in the Njombe-Penja Health District of Cameroon. This region is endemic for filarial infections, posing significant public health burden. Study Design: A cross-sectional study was conducted among 360 participants, representing various occupational groups and areas of settlements. Place and Duration of Study: The study was conducted in the Njombe-Penja Health District of the Littoral Region of Cameroon. Recruitment of participants, biological samples collection and questionnaire administration was done over a period of 1 month (July 2023). Methodology: Fifty microliters (50 µL) of peripheral blood was collected using capillary tubes, and analyzed for microfilarial presence and load. Structured questionnaires were used to collect data on demographic characteristics, exposure to risk factors, and preventive practices. Descriptive statistics, Chi-square tests with p-values, and odds ratios were calculated to identify significant associations. Results: The results showed a prevalence of 45.8% for M. perstans and 19.4% for L. loa, with higher infection rates among farmers, especially those working in the large scale banana farming sector, and those living near water bodies (P = .002, OR = 3.15). Poor environmental sanitation (P = .004, OR = 2.75), and low monthly income (&lt; 50,000 CFA) (P = .001, OR = 2.32), were also significantly associated with increased infection risk. Although 70.0% of participants were aware of the diseases, only 50.0% could identify key symptoms. Preventive measures like using bed nets and insect repellents were linked to a lower risk of infection (P =.003, OR = 2.10). Conclusion: Mansonella perstans and L. loa infections are highly prevalent in the district, driven by occupational exposure, socioeconomic factors, and environmental risks. Interventions should focus on improving sanitation, enhancing public health education, and expanding healthcare access.

Molecular detection of Potential Novel Mansonella species (Filarioidea: Onchocercidae) in equine and Culicoides enderleini from Africa

A new genotype of a filarial worm from the Mansonella genus was determined in three donkeys from Algeria, as well as from four horses and two Culicoides enderleini biting midges from Senegal. Phylogenetic analysis based on the ITS1 and rRNA 5S genes shows similar results clustering this filarial worm within the genus Mansonella with low identity with all known Mansonella species. Further research should be performed to characterise this Mansonella sp. and assess its prevalence in African countries.

Genetic characterization of immune adaptor molecule MyD88 in Culex pipiens complex (Diptera: Culicidae) mosquitoes from China.

Mosquitoes of the Culex (Cx.) pipiens complex are vectors of severe diseases including West Nile fever by West Nile virus, Japanese encephalitis by Japanese encephalitis virus, and Lymphatic filariasis by filarial nematode Wuchereria bancrofti. As a major portion of mosquito immune system, the Toll pathway implicates in response against infections of mosquito-borne pathogens and biocontrol agents. The genetic diversity of immune-related molecules is expected to be a feasible and effective introduction to expand our knowledge of the mosquito-microbe interplay. However, a comprehensive description is currently lacking regarding the genetic characteristic of the Toll pathway molecules in Cx. pipiens complex mosquitoes. In the present study, genetic changes in Cx. pipiens complex MyD88 (Myeloid differentiation primary response protein 88) were analyzed as a precedent for the Toll pathway molecules in this taxon. MyD88 is a critical adaptor of the pathway transducing signals from TIR-containing receptors to downstream death domain-containing molecules. Our results revealed that adaptive selection has influenced the genetic changes of the molecule, giving rise to acceleration of diversity at a number of amino acid sites. The adaptively selected sites lie in the death domain, intermediate domain, and C-terminal extension. The characteristics of the genetic changes shed insights into the prominent molecular-level structural basis and the involvement strategy of the adaptor in the arms race against exogenous challenges. This finding would be beneficial for further exploration and deeper understanding of the mosquitoes' vectorial capacity and facilitating the effectiveness and sustainability of the biocontrol agents.

Evaluation of the In2care Mosquito Station against Culex quinquefasciatus mosquitoes (Diptera: Culicidae) under semifield conditions.

Culex quinquefasciatus is an important mosquito vector responsible for the transmission of filarial worms, arthropod-borne viruses like Oropouche, St. Louis encephalitis, and West Nile and protozoans that cause avian malaria. Due to insecticide resistance documented in Cx. quinquefasciatus populations worldwide, integrated vector management programs can benefit from new strategies to control this species. The In2Care Mosquito Station (In2Care station), a commercially available dissemination station containing pyriproxyfen (PPF) and Beauveria bassiana spores, has been shown to be effective against skip-ovipositing Aedes aegypti and Aedes albopictus in previously conducted semifield and field trials. To determine the potential of Cx. quinquefasciatus adult females to autodisseminate PPF and if the In2Care station could be used for Cx. quinquefasciatus control, we assessed its efficacy in a semifield setting against wild Cx. quinquefasciatus. We found that the In2Care station was attractive to gravid Cx. quinquefasciatus females, with a significantly higher percentage of egg rafts laid in the In2Care station compared to alternative ovipots. Adult females successfully autodisseminated PPF from the In2Care station to surrounding ovipots, leading to a significant increase in mosquito emergence inhibition. Additionally, adult Cx. quinquefasciatus exposure to B. bassiana spores significantly reduced mosquito survivorship. These results suggest that the In2Care station may be effective against Cx. quinquefasciatus in addition to Ae. aegypti and Ae. albopictus. Additional field evaluations are needed to assess impacts at the population level.

Internalization of macromolecules into filarial parasites – Possible operation of host’s anti-fecundity immunity inside adult filarial nematodes

ObjectivesImmune effector mechanisms operating against large extracellular systemic pathogens, such as adult stages of filarial nematodes, are not clearly understood. The only immune effect on the adult worms appears to be directed towards embryos in adult worms. The role of IL-4 or TLR-4 in immune responses that inhibit embryogenesis in adult filarial worms has been well-documented. This host’s immune responses that control embryogenesis (anti-fecundity immunity) are considered critical and were addressed in the current study. The current investigation demonstrated the possible operation of anti-adult immunity that could be functional against large stage adults. MethodsAdult filaria worms were pulsed with macromolecules such as Concanavalin A, Human immunoglobulins, and Rabbit immunoglobulins for 6 hrs, and entry of these molecules was demonstrated using flow cytometry. Filaria worms were also preincubated with Latrunculin A, an endocytic inhibitor, to explain if macromolecules enter by endocytosis. ResultsUsing the flow cytometry approach, we could show the entry of immunoglobulins into the uterine cavity of female Setaria digitata, a cattle-dwelling filarial parasite. Immunoglobulins were observed to bind to the surface of intrauterine stages of female worms. We also demonstrated the presence of bovine immunoglobulins in different embryonic stages in situ. ConclusionsOverall, experimental evidence demonstrates the existence of the host’s immune molecules inside large-stage adult parasites. However, future studies are directed to understand the functional aspect of the presence of these effector molecules inside the adults.

Differences of in vitro immune responses between patent and pre-patent Litomosoides sigmodontis-infected mice are independent of the filarial antigenic stimulus used.

Lymphatic filariasis and onchocerciasis are neglected tropical diseases and cause significant public health problems in endemic countries, especially in sub-Saharan Africa. Since the human parasites are not viable in immune-competent mice, animal models have been developed, among them Litomosoides sigmodontis which permits a complete life cycle in BALB/c mice, including the development of patent infections with circulating microfilariae (Mf, the worm's offspring). To investigate the immunomodulatory properties of helminths in vitro, antigenic extracts can be prepared from different life cycle stages of the L. sigmodontis model, including adult worms, but the methods to prepare these antigens differ between research groups. This study analyzed whether different centrifugation methods during the preparation of an antigenic extract, the gender of used worms, or the different fractions (soluble or pellet) altered filarial-specific CD4+ Tcell responses. These cells were isolated from pre-patent or patent/chronic infected mice, hence those without and those with Mf, respectively. Ex vivo immune responses were compared at these two different time points of the infection as well as the parasitic parameters. Worm burden and cell infiltration were elevated in the thoracic cavity (TC) and draining mediastinal lymph nodes at the pre-patent stage. Within the TC, eosinophils were significantly up-regulated at the earlier time point of infection which was further reflected by the eosinophil-related eotaxin-1 levels. Regarding the production of cytokines by re-stimulated CD4+ T cells in the presence of different antigen preparations, cytokine levels were comparable for all used extracts. Our data show that immune responses differ between pre-patent and patent filarial infection, but not in response to the different antigenic extracts themselves.

Entomological assessment in 'hotspots' of four lymphatic filariasis endemic districts, Central Nepal during post-MDA surveillance.

Annual mass drug administration (MDA) is the main strategy to interrupt the transmission of lymphatic filariasis (LF) in the community. The main aim of monitoring the MDA program, for its effectiveness and interruption of LF is the post-MDA surveillance using antigen survey in children born after MDA. The latest technique of new research suggests that xenomonitoring is an effective tool for monitoring LF intervention. The objective of this study was to assess the W. bancrofti infection/or infectivity in vector mosquitoes by xenomonitoring during post-MDA surveillance. A descriptive cross-sectional study was conducted in the hotspots of selected four districts of Central Nepal. A gravid trap technique was used for sampling mosquitoes. Infection/or infectivity was determined via the dissection of vector mosquitoes. Anopheles, Aedes, Armigerus and Culex species were collected from hotspots of four endemic districts, two from the hilly region (Lalitpur and Dhading) and two from Terai region (Bara and Mahottari) of Central Nepal. A total of 4450 mosquitoes belonging to four genera, Anopheles, Culex, Armigeres, and Aedes were collected from four hotspots. The distribution of Culex quinquefasciatus was found to be the highest, 88.9% (n=3955/4450) followed by Cx. vishnui (4.5%), Armigeres sp (5.8%), An. culicifascies (0.2%), Aedes spp (0.8%). The proportion of female mosquitoes trapped is significantly higher. A total of 3344 parous Cx. quinquefasciatus mosquitoes were dissected for any larval stage of W. bancrofti. We could not find any filarial infection in dissected mosquito samples. We conclude that the gravid trap is an efficient tool for the collection of gravid Cx. quinquefasciatus mosquitoes for xenomonitoring studies of filariasis endemic regions. Vector composition indicated a maximum number of vector mosquitoes of lymphatic filariasis were trapped compared with the other three species. Distribution and density of Cx. quinquefasciatus was found highest in four hotspots of endemic districts. None of the Cx. quinquefasciatus dissected were found to be infected by larval forms of filaria. Since the low levels of infection persistence in the human population in these hot spots, vector infection and infectivity can't be ignored. Microscopic xenomonitoring at a low level of infection persistent is less likely to be efficient so molecular xenomonitoring along with a large sample should be required in each of the hot spots of the districts. Additionally, area is receptive so further vector control intervention should be required to reduce the risk of resurgence of infection.

Updated annotation and meta-analysis of Brugia malayi transcriptomics data reveals consistent transcriptional profiles across time and space with some study-specific differences in adult female worm transcriptional profiles.

Genomics, transcriptomics, and proteomics have significantly advanced our understanding of obligately host-associated microbes, where interrogation of the biology is often limited by the complexity of the biological system and limited tools. This includes the causative agents of many neglected tropical diseases, including filarial nematodes. Therefore, numerous transcriptomics studies have been undertaken on filarial nematodes. Most of these transcriptomics studies focus on Brugia malayi, which causes lymphatic filariasis and is a laboratory model for human filarial disease. Here, we undertook a meta-analysis of the publicly available B. malayi transcriptomics data enabling the direct cross comparison of samples from almost a dozen studies. This reanalysis highlights the consistency of transcriptomics results across many different studies and experimental designs from across the globe for over a decade of research, across many different generations of a sequencing technology, library preparation protocols, and differential expression tools. Males and microfilariae across samples had similar expression profiles. However, female samples were clustered into two differential expression patterns that were significantly different from one another. Largely, we confirm previous results for all studies reanalyzed including tissue-specific gene expression and anti-Wolbachia doxycycline treatment of microfilaria. However, we did not detect previously reported differential expression upon in vitro or in vivo treatment with ivermectin, albendazole, and DEC, instead identifying a consistent lack of transcriptomic change upon exposure to these anthelminthic drugs. Updated annotation has been provided that denotes poorly supported genes including those overlapping rRNAs.