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Parasitology Research Jan 2013Lymphatic filariasis (LF) is a disabling and disfiguring disease resulting from a mosquito-borne parasitic infection. It is a major public health problem in many... (Review)
Review
Lymphatic filariasis (LF) is a disabling and disfiguring disease resulting from a mosquito-borne parasitic infection. It is a major public health problem in many countries with a warm climate. Research and control activities have mainly focused on LF in rural areas where it also has its major impact. However, with rapid and unplanned growth of cities in the developing world, there is a need also to consider LF transmission and control in urban settings. Here, we review currently available knowledge on urban LF and the environmental and socio-economic basis for its occurrence. Among the three parasite species causing LF in humans, only Wuchereria bancrofti has been documented to have a significant potential for urban transmission. This is primarily because one of its vectors, Culex quinquefasciatus, thrives and proliferates excessively in crowded city areas with poor sanitary, sewerage and drainage facilities. For this reason, urban LF also often shows a marked focality in distribution, with most cases clustered in areas inhabited by the less privileged city populations. More knowledge on urban LF is needed, in particular on its socio-economic and human behavioural context, on the potential for transmission in regions where other LF vector species predominate, and on rapid methods for identification and mapping of risk areas, to provide a strong evidence base for its control.
Topics: Animals; Culex; Disease Vectors; Ecosystem; Elephantiasis, Filarial; Humans; Socioeconomic Factors; Urban Population; Wuchereria bancrofti
PubMed: 23239094
DOI: 10.1007/s00436-012-3226-x -
Tropical Medicine & International... Nov 2014Several cases of lymphatic filariasis (LF) have been reported in non-endemic countries due to travellers, military personnel and expatriates spending time in and... (Review)
Review
OBJECTIVE
Several cases of lymphatic filariasis (LF) have been reported in non-endemic countries due to travellers, military personnel and expatriates spending time in and returning from endemic areas, as well as immigrants coming from these regions. These cases are reviewed to assess the scale and context of non-endemic presentations and to consider the biological factors underlying their relative paucity.
METHODS
Cases reported in the English, French, Spanish and Portuguese literature during the last 30 years were examined through a search of the PubMed, ProMED-mail and TropNet resources.
RESULTS
The literature research revealed 11 cases of lymphatic filariasis being reported in non-endemic areas. The extent of further infections in recent migrants to non-endemic countries was also revealed through the published literature.
CONCLUSIONS
The life-cycle requirements of Wuchereria and Brugia species limit the extent of transmission of LF outside of tropical regions. However, until elimination, programmes are successful in managing the disease, there remains a possibility of low rates of infection being reported in non-endemic areas, and increased international travel can only contribute to this phenomenon. Physicians need to be aware of the signs and symptoms of lymphatic filariasis, and infection should be considered in the differential diagnosis of people with a relevant travel history.
Topics: Adult; Aged; Animals; Child; Disease Transmission, Infectious; Elephantiasis, Filarial; Emigrants and Immigrants; Endemic Diseases; Female; Humans; Male; Middle Aged; Togo; Travel; Wuchereria bancrofti
PubMed: 25145445
DOI: 10.1111/tmi.12376 -
Clinical Microbiology and Infection :... Jul 2011Lymphatic filariasis (LF) and onchocerciasis are parasitic nematode infections that are responsible for a major disease burden in the African continent. Disease symptoms... (Review)
Review
Lymphatic filariasis (LF) and onchocerciasis are parasitic nematode infections that are responsible for a major disease burden in the African continent. Disease symptoms are induced by the immune reactions of the host, with lymphoedema and hydrocoele in LF, and dermatitis and ocular inflammation in onchocerciasis. Wuchereria bancrofti and Onchocerca volvulus, the species causing LF and onchocerciasis in Africa, live in mutual symbiosis with Wolbachia endobacteria, which cause a major part of the inflammation leading to symptoms and are antibiotic targets for treatment. The standard microfilaricidal drugs ivermectin and albendazole are used in mass drug administration programmes, with the aim of interrupting transmission, with a consequent reduction in the burden of infection and, in some situations, leading to regional elimination of LF and onchocerciasis. Co-endemicity of Loa loa with W. bancrofti or O. volvulus is an impediment to mass drug administration with ivermectin and albendazole, owing to the risk of encephalopathy being encountered upon administration of ivermectin. Research into new treatment options is exploring several improved delivery strategies for the classic drugs or new antibiotic treatment regimens for anti-wolbachial chemotherapy.
Topics: Africa; Albendazole; Animals; Elephantiasis, Filarial; Filaricides; Humans; Ivermectin; Onchocerca volvulus; Onchocerciasis; Symbiosis; Wolbachia; Wuchereria bancrofti
PubMed: 21722251
DOI: 10.1111/j.1469-0691.2011.03586.x -
Revista Da Associacao Medica Brasileira... 2007The rupture or fistulization of lymph vessels into the urinary system, known as chyluria (milky urine), is caused mainly by bancroftian filariasis. On rare occasions... (Review)
Review
The rupture or fistulization of lymph vessels into the urinary system, known as chyluria (milky urine), is caused mainly by bancroftian filariasis. On rare occasions chyluria may also be caused by neoplasia, lymphatic malformation, abdominal trauma, as well as other infectious diseases such as tuberculosis. The authors proposed general guidelines to manage patients suffering from milky urine in Bancroftian filariasis endemic and non-endemic areas. They emphasized the importance of a careful diagnostic process accomplished using screening procedures, evaluating a detailed history of illness and performing a careful physical examination, targeting on the most suitable diagnostic tools for each case. In addition, they emphasized the need to manage the patient from a broader perspective, which goes beyond the medical aspect, involving also social and nutritional contexts. In the great majority of cases, controlling chyluria is fundamentally based on patient education and adjustment to a low lipid, high protein diet in addition to increased fluid intake.
Topics: Animals; Chyle; Diagnosis, Differential; Diet; Humans; Urinary Fistula; Urine; Wuchereria bancrofti
PubMed: 17952358
DOI: 10.1590/s0104-42302007000500025 -
Infection, Genetics and Evolution :... Dec 2014Wuchereria bancrofti (Wb) is the most widely distributed of the three nematodes known to cause lymphatic filariasis (LF), the other two being Brugia malayi and Brugia... (Review)
Review
Wuchereria bancrofti (Wb) is the most widely distributed of the three nematodes known to cause lymphatic filariasis (LF), the other two being Brugia malayi and Brugia timori. Current tools available to monitor LF are limited to diagnostic tests targeting DNA repeats, filarial antigens, and anti-filarial antibodies. While these tools are useful for detection and surveillance, elimination programs have yet to take full advantage of molecular typing for inferring infection history, strain fingerprinting, and evolution. To date, molecular typing approaches have included whole mitochondrial genomes, genotyping, targeted sequencing, and random amplified polymorphic DNA (RAPDs). These studies have revealed much about Wb biology. For example, in one study in Papua New Guinea researchers identified 5 major strains that were widespread and many minor strains some of which exhibit geographic stratification. Genome data, while rare, has been utilized to reconstruct evolutionary relationships among taxa of the Onchocercidae (the clade of filarial nematodes) and identify gene synteny. Their phylogeny reveals that speciation from the common ancestor of both B. malayi and Wb occurred around 5-6 millions years ago with shared ancestry to other filarial nematodes as recent as 15 million years ago. These discoveries hold promise for gene discovery and identifying drug targets in species that are more amenable to in vivo experiments. Continued technological developments in whole genome sequencing and data analysis will likely replace many other forms of molecular typing, multiplying the amount of data available on population structure, genetic diversity, and phylogenetics. Once widely available, the addition of population genetic data from genomic studies should hasten the elimination of LF parasites like Wb. Infectious disease control programs have benefited greatly from population genetics data and recently from population genomics data. However, while there is currently a surplus of data for diseases like malaria and HIV, there is a scarcity of this data for filarial nematodes. With the falling cost of genome sequencing, research on filarial nematodes could benefit from the addition of population genetics statistics and phylogenetics especially in dealing with elimination programs. A comprehensive review focusing on population genetics of filarial nematode does not yet exist. Here our goal is to provide a current overview of the molecular epidemiology of W. bancrofti (Wb) the primary causative agent of LF. We begin by reviewing studies utilizing molecular typing techniques with specific focus on genomic and population datasets. Next, we used whole mitochondrial genome data to construct a phylogeny and examine the evolutionary history of the Onchocercidae. Then, we provide a perspective to aid in understanding how population genetic techniques translate to modern epidemiology. Finally, we introduce the concept of genomic epidemiology and provide some examples that will aid in future studies of Wb.
Topics: Animals; Elephantiasis, Filarial; Evolution, Molecular; Genetic Variation; Humans; Molecular Epidemiology; Molecular Typing; Phylogeny; Prevalence; Wuchereria bancrofti
PubMed: 25176600
DOI: 10.1016/j.meegid.2014.08.018 -
Parasite Immunology Aug 2014The immune responses to filarial parasites encompass a complex network of innate and adaptive cells whose interaction with the parasite underlies a spectrum of clinical... (Review)
Review
The immune responses to filarial parasites encompass a complex network of innate and adaptive cells whose interaction with the parasite underlies a spectrum of clinical manifestations. The predominant immunological feature of lymphatic filariasis is an antigen-specific Th2 response and an expansion of IL-10 producing CD4(+) T cells that is accompanied by a muted Th1 response. This antigen-specific T-cell hyporesponsiveness appears to be crucial for the maintenance of the sustained, long-standing infection often with high parasite densities. While the correlates of protective immunity to lymphatic filariasis are still incompletely understood, primarily due to the lack of suitable animal models to study susceptibility, it is clear that T cells and to a certain extent B cells are required for protective immunity. Host immune responses, especially CD4(+) T-cell responses clearly play a role in mediating pathological manifestations of LF, including lymphedema, hydrocele and elephantiasis. The main underlying defect in the development of clinical pathology appears to be a failure to induce T-cell hyporesponsiveness in the face of antigenic stimulation. Finally, another intriguing feature of filarial infections is their propensity to induce bystander effects on a variety of immune responses, including responses to vaccinations, allergens and to other infectious agents. The complexity of the immune response to filarial infection therefore provides an important gateway to understanding the regulation of immune responses to chronic infections, in general.
Topics: Animals; Brugia; CD4-Positive T-Lymphocytes; Disease Models, Animal; Elephantiasis, Filarial; Humans; Immunity, Cellular; Interleukin-10; Wuchereria bancrofti
PubMed: 24134686
DOI: 10.1111/pim.12081 -
Parasites & Vectors Sep 2021Lymphatic filariasis (LF) is a parasitic disease caused by the worms Wuchereria bancrofti, Brugia malayi, or Brugia timori. It is a tropical and subtropical illness that... (Review)
Review
Lymphatic filariasis (LF) is a parasitic disease caused by the worms Wuchereria bancrofti, Brugia malayi, or Brugia timori. It is a tropical and subtropical illness that affects approximately 67 million people worldwide and that still requires better diagnostic tools to prevent its spread and enhance the effectiveness of control procedures. Traditional parasitological tests and diagnostic methods based on whole protein extracts from different worms are known for problems related to sample time collection, sensitivity, and specificity. More recently, new diagnostic tools based on immunological methods using recombinant antigens have been developed. The current review describes the several recombinant antigens used as tools for lymphatic filariasis diagnosis in antigen and antibody capture assays, highlighting their advantages and limitations as well as the main commercial tests developed based on them. The literature chronology is from 1991 to 2021. First, it describes the historical background related to the identification of relevant antigens and the generation of the recombinant polypeptides used for the LF diagnosis, also detailing features specific to each antigen. The subsequent section then discusses the use of those proteins to develop antigen and antibody capture tests to detect LF. So far, studies focusing on antibody capture assays are based on 13 different antigens with at least six commercially available tests, with five proteins further used for the development of antigen capture tests. Five antigens explored in this paper belong to the SXP/RAL-2 family (BmSXP, Bm14, WbSXP-1, Wb14, WbL), and the others are BmShp-1, Bm33, BmR1, BmVAH, WbVAH, BmALT-1, BmALT-2, and Wb123. It is expected that advances in research with these antigens will allow further development of tests combining both sensitivity and specificity with low costs, assisting the Global Program to Eliminate Lymphatic Filariasis (GPELF).
Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Brugia; Elephantiasis, Filarial; Helminth Proteins; Humans; Immunoglobulin G; Sensitivity and Specificity; Wuchereria bancrofti
PubMed: 34526120
DOI: 10.1186/s13071-021-04980-3 -
Memorias Do Instituto Oswaldo Cruz 1987
Comparative Study
Topics: Animals; Brazil; Circadian Rhythm; Disease Vectors; Elephantiasis, Filarial; Filariasis; Histamine H1 Antagonists; Humans; Microfilariae; National Health Programs; Wuchereria bancrofti
PubMed: 2908187
DOI: 10.1590/s0074-02761987000800070 -
Ethiopian Journal of Health Sciences Mar 2020Lymphatic filariasis (LF) is a neglected tropical disease (NTD) vectored by mosquito; and people in rural areas are mostly at risk of infection. Pooling prevalence data... (Review)
Review
BACKGROUND
Lymphatic filariasis (LF) is a neglected tropical disease (NTD) vectored by mosquito; and people in rural areas are mostly at risk of infection. Pooling prevalence data across the six geo-political zones of Nigeria is expected to provide a clearer insight into the burden of the disease as this information could guide towards planning eradication programmes.
METHODS
Search for pertinent literature was done on Google Scholar, African Journal Online (AJOL) and PubMed databases using relevant keywords. Studies on the prevalence of LF due to Wuchereria bancrofti in Nigeria were selected and reviewed. Prevalence data from the different states were further organized into the six geopolitical zones and analyzed.
RESULTS
Of the 36 states in Nigeria, prevalence data were available only for 19 states. Furthermore, in the six geopolitical zones, North-West had the highest disease burden (44 per 10 000) of Years Lived with Disability (YLD), while North-Central (4 per 10 000) had the lowest disease burden.
CONCLUSION
Result are largely attributed to the prevailing conditions in the different zones. In view of ensuring a successful control plan and eventual eradication of the disease, a comprehensive national survey in every state should be carried out using more sensitive tools.
Topics: Animals; Cost of Illness; Filariasis; Humans; Nigeria; Prevalence; Wuchereria bancrofti
PubMed: 32165820
DOI: 10.4314/ejhs.v30i2.18 -
Parasite (Paris, France) Sep 2008The author discusses the significance, implications and limitations of Manson's work. How did Patrick Manson resolve some of the major problems raised by the filarial... (Review)
Review
The author discusses the significance, implications and limitations of Manson's work. How did Patrick Manson resolve some of the major problems raised by the filarial worm life cycle? The Amoy physician showed that circulating embryos could only leave the blood via the percutaneous route, thereby requiring a bloodsucking insect. The discovery of a new autonomous, airborne, active host undoubtedly had a considerable impact on the history of parasitology, but the way in which Manson formulated and solved the problem of the transfer of filarial worms from the body of the mosquito to man resulted in failure. This article shows how the epistemological transformation operated by Manson was indissociably related to a series of errors and how a major breakthrough can be the result of a series of false proposals and, consequently, that the history of truth often involves a history of error.
Topics: Animals; Culicidae; Filariasis; Humans; Insect Vectors; Parasitology; Wuchereria bancrofti
PubMed: 18814729
DOI: 10.1051/parasite/2008153495