Filaria Journal - Most accessed articles

Lymphatic Filariasis (Elephantiasis) Elimination: A public health success and development opportunity

David Molyneux — 2003-09-09T00:00:00Z

Background: The Global Programme to Eliminate Lymphatic Filariasis, launched following World Health Assembly Resolution 50.29 (WHA 50.29), has been facilitated in its progress by new research findings, drug donations, the availability of diagnostic tools, disability management strategies to help those already suffering and the development of partnerships. The strategy recommended by the World Health Organization of annual treatment with a two-drug combination has proved safe.DiscussionUsing different approaches in several countries the elimination of lymphatic filariasis (LF) has been demonstrated to be feasible during earlier decades. These successes have been largely overlooked. However, the programme progress since 2000 has been remarkable – upscaling rapidly from 2 million treatments in 2000 to approximately 60 million in 2002. Around 34 countries had active programmes at the end of 2002. It is anticipated that there will be further expansion – but this will be dependent on additional resources becoming available. The programme also provides significant opportunities for other disease control programmes to deliver public health benefits on a large scale. Few public health programmes have upscaled so rapidly and so cost-effectively (<$0.03/treatment in some Asian settings) – one country treating 9–10 million people in a day (Sri Lanka). The LF programme is arguably the most effective pro-poor public health programme currently operating which is based on country commitment and partnerships supported by a global programme and alliance. Tables are provided to summarize programme characteristics, the benefits of LF elimination, opportunities for integration with other programmes and relevance to the Millennium Development Goals.SummaryLymphatic filariasis elimination is an "easy-to-do" inexpensive health intervention that provides considerable "beyond filariasis" benefits, exemplifies partnership and is easily evaluated. The success in global health action documented in this paper requires and deserves further support to bring to fruition elimination of lymphatic filariasis as a public health problem and health benefits to poor people. A future free of lymphatic filariasis will reduce poverty and bring better health to poor people, prevent disability, strengthen health systems and build partnerships.

Animated documentation of the filaria dance sign (FDS) in bancroftian filariasis

Sabine Mand — 2003-02-27T00:00:00Z

Background: Ultrasonography is able to detect adult Wuchereria bancrofti worms in scrotal lymphatic vessels of infected men on account of the characteristic pattern of adult worm movements, known as the filarial dance sign. Furthermore, the technique is able to delineate associated pathology, such as hydrocoele and lymphoedema, which can be diagnosed in early stages. Ultrasonography is also useful in the assessment of macrofilaricidal effects of antifilarial medication.The purpose of this study was to evaluate the usefulness of scrotal ultrasonography, in combination with a new method of digital documentation, in men infected with Wuchereria bancrofti. Methods: Ultrasonography of the scrotal areas was carried out in 33 male patients from an endemic area in Ghana using a hand-carried ultrasound system and a linear array transducer at 7.5 MHz. Wuchereria bancrofti infection was also assessed by quantification of night blood microfilaraemia and semi-quantitative detection of circulating filarial antigen. Ultrasound findings were documented by print outs and by Digital Video sequences directly exported from the ultrasound machine which were edited in Final Cut Pro 3® and exported, using QuickTime® Pro, as MPEG-1 video. Results: Worm nests, i.e. dilated lymphatic vessels with the characteristic movement patterns of worms, were found in all patients, and typical examples of larger as well as smaller nests are presented through MPEG-1 video in b- and m-modes as well as Colour Doppler and Pulse Wave Doppler images. Conclusion: In this study, the filarial dance sign is being made available on the Internet to readers through MPEG-1 video. This method allows for demonstration of movement patterns rather than static images. In addition, the pathologic ultrasonographic signs of filariasis can be rapidly relayed over great distances and may be helpful to other investigators or clinicians in the diagnosis of patients infected with Wuchereria bancrofti.

Mapping of lymphatic filariasis in Nepal

Jeevan Sherchand — 2003-03-19T00:00:00Z

Background: Human infection with Wuchereria bancrofti causes a disabling parasitic disease known as lymphatic filariasis, which is a major public health and socio-economic problem in many parts of the world. At the onset of the study, little was known of the distribution of filariasis and its current importance as a public health problem in Nepal. Methods: Epidemiological mapping was undertaken to determine the prevalence of infection by Wuchereria bancrofti in 37 districts of Nepal between July to December 2001. The study population above 15 years of age was selected, and the immunochromatographic test (ICT Filariasis) was used to screen for circulating filarial antigen (CFA). Results: The overall prevalence of lymphatic filariasis from a 4,488-sample population was 13% and 33/37 districts were found to be endemic. On the basis of geographical data, the highest number of cases was found at altitudes between 500–700 m; however, a substantial number of infected individuals were found in the highly populated Kathmandu valley, at altitudes between 900–1,500 metres where transmission appears to take place. Prevalence rates above 20% were found in 11 districts (with the highest rate of 40%), 6–19% were found in 15 districts, and 0.1–5% were in 7 districts.Information on people's knowledge, attitudes and behaviour towards filariasis was also collected by means of a structured questionnaire, which is presented and discussed in the study. Conclusions: This is the most extensive study of lymphatic filariasis undertaken to date in Nepal. The study indicates that the prevalence of infection is far greater that was previously reported and that lymphatic filariasis should be a much higher health priority than currently given.

Some observations on the effect of Daflon (micronized purified flavonoid fraction of Rutaceae aurantiae) in bancroftian filarial lymphoedema

Lalit Das — 2003-03-12T00:00:00Z

Background: Morbidity management is a core component of the global programme for the elimination of lymphatic filariasis. In a double-blind clinical trial, the tolerability and efficacy of Daflon (500 mg) + DEC (25 mg) or DEC (25 mg) alone, twice daily for 90 days, was studied in 26 patients with bancroftian filarial lymphoedema. Results: None of the patients in either drug group reported any adverse reaction throughout the treatment period (90 days). Haematological and biochemical parameters were within normal limits and there was no significant difference between the pre-treatment (day 0) and post-treatment (day 90) values. The group receiving Daflon showed significant reduction in oedema volume from day 90 (140.6 ± 18.8 ml) to day 360 (71.8 ± 20.7 ml) compared to the pre-treatment (day 0, 198.4 ± 16.5 ml) value. This accounted for a 63.8% reduction in oedema volume by day 360 (considering the pre-treatment (day 0) as 100%). In the DEC group, the changes in oedema volume (between day 1 and day 360) were not significant when compared to the pre-treatment (day 0) value. The percentage reduction at day 360 was only 9%, which was not significant (P > 0.05). Conclusion: This study has shown that Daflon (500 mg, twice a day for 90 days) is both safe and efficacious in reducing oedema volume in bancroftian filarial lymphoedema. Further clinical trials are essential for strengthening the evidence base on the role of this drug in the morbidity management of lymphatic filariasis.

Monitoring lymphatic filariasis interventions: Adult mosquito sampling, and improved PCR - based pool screening method for Wuchereria bancrofti infection in Anopheles mosquitoes

Daniel Boakye — 2007-11-29T00:00:00Z

Background: Monitoring and evaluation are essential to the successful implementation of mass drug administration programmes for LF elimination. Monitoring transmission when it is low requires both large numbers of mosquito vectors and sensitive methods for detecting Wuchereria bancrofti infections in them. PCR-based methods are preferred over classical dissections but the best protocol so far achieved detection of one L3 Wuchereria bancrofti larva in a pool of 35–50 Anopheles mosquitoes. It also lacks consistency and remains still a costly tool. Hence we decided to improve upon this to achieve detection in a pool of 100 or more by enhancing the quality of the template DNA. Prior to this we also evaluated three vector sampling methods in the context of numbers for monitoring. Methods: Human landing, pyrethrium spray and light traps catches were conducted concurrently at sites in an LF endemic district in Ghana and the numbers obtained compared. Two DNA extraction methods; Bender buffer and phenol/chloroform purification, and DNAeasy Tissue kit (Quaigen Inc) were used on pools of 25, 50, 75 100 and 150 mosquitoes each seeded with one L3 or its quivalent amount of DNA. Then another set of extracted DNA by the two methods was subjected to Dynal bead purification method (using capture oligonucleotide primers). These were used as template DNA in PCR to amplify W. bancrofti sequences. The best PCR result was then evaluated in the field at five sites by comparing its results (infections per 1000 mosquitoes) with that of dissection of roughly equal samples sizes. Results: The largest numbers of mosquitoes were obtained with the human landing catches at all the sites sampled. Although PCR detection of one L3 in pools of 25, 50 and 75 mosquitoes was consistent irrespective of the extraction method, that of one L3 in 100 was only achieved with the kit-extracted DNA/Dynal bead purification method. Infections were found at only two sites by both dissection and pool-screening being 14.3 and 19 versus 13.4 and 20.1 per 1000 Anopheles mosquitoes respectively, which were not statistically significantDiscussion and conclusionHLC still remains the best option for sampling for the large numbers of mosquitoes required for monitoring transmission during MDA programmes, when vector population densities are high and classical indices of transmission are required. One – in – 100 detection is an improvement on previous PCR pool-screening methods, which in our opinion was a result of the introduction of the extra step of parasite DNA capture using Dynal/beads. As pool sizes increase the insects DNA will swamp parasite DNA making the latter less available for an efficient PCR, therefore we propose either additional steps of parasite DNA capture or real-time PCR to improve further the pool screening method. The study also attests also to the applicability of Katholi et al's algorithm developed for determining onchocerciasis prevalence in LF studies.

Behaviour of filariae: morphological and anatomical signatures of their life style within the arthropod and vertebrate hosts

Odile Bain — 2003-12-15T00:00:00Z

This paper attempts to pinpoint the most original morphological anatomical features of the biology of filariae per se and those which are or could be important for triggering regulatory processes in the arthropod vector and uncontrolled pathogenic processes in the vertebrate hosts. The following stages are considered: the motile egg or newly-hatched larva, the microfilaria, in the lymphatic or blood vessels of its vertebrate host; the larva, its migrations and its intrasyncitial development in the hematophagous arthropod subverted as vector; its transfer to the vertebrate host, migratory properties through the lymphatic system, maturation, mating and, finally, egg laying in the tissues they reach. This synthesis is based on parasite morphological features and their functional interpretation, histological features in the different niches the filariae reach, and on quantitative analyses of filarial development at its different phases, as well as on the rare and valuable observations of living parasites in situ. Data have been drawn from various species of Onchocercidae from amphibians, reptiles, birds and mammals. These comparative analyses have revealed the major constraints to which the filariae, including those parasitizing humans, have been subjected during their evolution from their ancestors, the oviparous and heteroxenic spirurids. Emphasis is placed on mechanical events: resistance of the microfilariae to the currents in the blood or lymph vessels, regulatory processes induced in the vector mesenteron by the movements of the ingested microfilariae, transient disruption by the microfilarial cephalic hook of the vectors' tissues and cell membranes during microfilarial translocation, attachment of males to females during mating by means of 'non-slip' systems, etc. Like other nematodes, filariae are equipped with sensory organs and a locomotor system, composed of the muscles and of the original osmoregulatory-excretory cell. Any change in one of these elements will result in the destruction of the filaria, at some stage of its development. In the vertebrate host, the intravascular stages will no longer be able to resist being carried passively towards the organs of destruction such as the lymph nodes or the lungs.

The geographical distribution of lymphatic filariasis infection in Malawi

Bagrey Ngwira — 2007-11-29T00:00:00Z

Mapping distribution of lymphatic filariasis (LF) is a prerequisite for planning national elimination programmes. Results from a nation wide mapping survey for lymphatic filariasis (LF) in Malawi are presented. Thirty-five villages were sampled from 23 districts excluding three districts (Karonga, Chikwawa and Nsanje) that had already been mapped and Likoma, an Island, where access was not possible in the time frame of the survey. Antigenaemia prevalence [based on immunochromatographic card tests (ICT)] ranged from 0% to 35.9%. Villages from the western side of the country and distant from the lake tended to be of lower prevalence. The exception was a village in Mchinji district on the Malawi-Zambia border where a prevalence of 18.2% was found. In contrast villages from lake shore districts [Salima, Mangochi, Balaka and Ntcheu (Bwanje valley)] and Phalombe had prevalences of over 20%.A national map is developed which incorporates data from surveys in Karonga, Chikwawa and Nsanje districts, carried out in 2000. There is a marked decline in prevalence with increasing altitude. Further analysis revealed a strong negative correlation (R2 = 0.7 p < 0.001) between altitude and prevalence. These results suggest that the lake shore, Phalombe plain and the lower Shire valley will be priority areas for the Malawi LF elimination programme. Implications of these findings as regards implementing a national LF elimination programme in Malawi are discussed.

The Elimination of Lymphatic Filariasis: A Strategy for Poverty Alleviation and Sustainable Development – Perspectives from the Philippines

Jamie Galvez Tan — 2003-07-21T00:00:00Z

Background: Within the Philippines areas endemic for lymphatic filariasis are in regions with the highest incidence of poverty. Out of a total of 79 provinces, 39 have a higher poverty incidence than the national average and 30 of these 39 provinces are endemic for lymphatic filariasis.DiscussionRecognizing that provinces endemic for lymphatic filariasis (LF) are also the poorest provinces, the elimination of lymphatic filariasis in these areas presents significant opportunities to reduce poverty and inequalities in health. The implementation of an effective national programme for the elimination of lymphatic filariasis will provide means for sustainable development at national, local and community levels.SummaryThe elimination of lymphatic filariasis as a public health problem is a 20-year strategic plan for the world community, with the vision of all endemic communities free of transmission of lymphatic filariasis by 2020 and with the commitment to ensure the delivery of quality technologies and human services to eliminate lymphatic filariasis worldwide through a multi-stakeholder global alliance of all endemic countries. This global goal of elimination of lymphatic filariasis is a significant opportunity for partnerships – a world with less poverty through sustainable development and free from the scourge of lymphatic filariasis.

Epidemiology and psycho-social aspects Of onchocercal skin diseases in northeastern Nigeria

Ikem Okoye — 2007-12-03T00:00:00Z

Background: Observations were made on the prevalence of onchocerciasis and Onchocercal Skin Diseases (OSD); frequency of occurrence and anatomical distribution of OSD in the Hawal River Valley, an established onchocerciasis endemic focus in north-eastern Nigeria. Methods: Symptoms of OSD were diagnosed in 5 844 subjects using Rapid Assessment Method (RAM) while 1 479 of the subjects chosen from alternate households had their skin biopsies examined for active microfilariae of Onchocerca volvulus. Also, Focal Group Discussions (FGD) were conducted at the Health District levels. Results: O. volvulus was recorded in (19.0%) and OSD in (43.8%) of the subjects. The Mantel-Haenszel test for linear association showed a close agreement between onchocerciasis prevalence and the rate of OSD (χ2 = 3.93; p < 0.05). The various forms of OSD occurred in the order: CPOD (17.7%), APOD (9.9%), DPM (9.0%), LOD (7.0%) and ATR (3.1%). The overall frequency of occurrence of various symptoms of OSD on different anatomical locations showed the locations in descending order of occurrence as lower limbs (24.6%), upper limbs (21.3%), buttocks (19.9%), shoulder & neck (19.1%), abdomen and trunk (11.3%), backside (10.6), and 'other' sites (7.5%). The Focal Group Discussion (FGD) revealed the most worrisome consequences of OSD as social isolation of victims (31.3%), shame and low self esteem (22.7%) and high cost of medication (15.6%). Conclusion: It is recommended that Onchocerciasis control programmes in the Hawal River Valley and any other focus with high incidence of OSD should incorporate an aspect that would address the anxiety and depression caused by various OSD lesions since they carry lots of psycho-social implications. This would increase acceptance and compliance of the target population. The classification criteria of onchocerciasis endemicity should be based on either or both of the O. volvulus and onchocercal skin disease burden of any community and no longer on O. volvulus parasitic infection rate alone.

Contributions of different mosquito species to the transmission of lymphatic filariasis in central Nigeria: Implications for monitoring infection by PCR in mosquito pools

Audrey Lenhart — 2007-11-29T00:00:00Z

Background: Members of the Anopheles gambiae complex are important vectors of lymphatic filariasis (LF) in sub-Saharan Africa, but little is known about the relative contributions of all mosquitoes to lymphatic filariasis transmission in this area. Methods: Over a 28 month period, mosquitoes were collected from 13 villages in Plateau and Nasarawa states in central Nigeria and dissected to determine W. bancrofti infection status. Wings and legs from a subset of the mosquitoes visually identified as A. gambiae s.l. were identified by PCR as either A. gambiae s.s. or A. arabiensis. Results: A. gambiae s.s peaked in abundance during the rainy season while A. arabiensis predominated during drier parts of the year. Both species were found equally likely to be infected with the developing stages (L1-L3) of W. bancrofti (9.2% and 11.1%, respectively). Fewer A. funestus (1.1%, p < 0.001) were infected than A. gambiae s.l. Conclusion: Understanding the relative contributions of morphologically indistinguishable species to LF transmission is essential if PCR is to be performed on mosquito pools. In the study area, the use of mosquito pools composed of A. gambiae sibling species would not be problematic, as both A. gambiae s.s. and A. arabiensis contribute equally to LF transmission.