Gerusa Dreyer

Pathogenesis of Lymphatic Disease in Bancroftian Filariasis:: A Clinical Perspective

The pathogenesis of lymphatic filariasis has been a matter of debate for many decades. Here, Gerusa Dreyer and colleagues propose a dynamic model of bancroftian filariasis, integrating clinical, parasitological, surgical, therapeutic, ultrasonographic and histopathological data. This model has profound implications for filariasis control programs and the management of the individual patient.

Bancroftian filariasis in a paediatric population : an ultrasonographic study

Little is known about lymphatic filariasis or the anatomical location of adult Wuchereria bancrofti in children. Seventy-eight children from Greater Recife, 23 microfilaria-positive and 55 microfilaria-negative in approximately 60 microL blood, underwent ultrasound examinations of the major superficial lymphatic vessels of the limbs, scrotal area (boys), and breast area (girls). The characteristic movements of adult worms, known as the filaria dance sign (FDS), were detected in 11 (14.1%) children. In 9 boys, the FDS was detected in lymphatic vessels of the scrotal area (8, ages 14-16) and the inguinal cord (1, age 11). In girls, the FDS was detected in a crural lymphatic vessel and an axillary lymph node. FDS detection was more common in boys (P = 0.06), older children (P = 0.001), and children with microfilaraemia (P = 0.05). Diffuse lymphangiectasia was visualized in 4 boys (ages 14-16) and 2 children had clinical signs of filariasis. These ultrasonographic findings associate W. bancrofti with both infection and disease in children.

Progression of lymphatic vessel dilatation in the presence of living adult Wuchereria bancrofti

Bancroftian filariasis, a mosquito-transmitted disease commonly known as elephantiasis, is caused by infection with the parasite Wuchereria bancrofti. Infection with this parasite can induce a broad array of chronic debilitating and socially stigmatizing conditions, but the pathogenesis of this morbidity remains obscure. Recent evidence indicates that in filariasis-endemic areas the primary lesion is not lymphatic vessel obstruction but, rather, dilatation. To determine the extent to which lymphatic dilatation occurs in the presence of living adult W. bancrofti, we performed longitudinal ultrasonographic measurements in 80 men (mean age 24 years) in Brazil who had a total of 107 W. bancrofti nests detectable by ultrasound. Initial mean lymphatic vessel diameter at the site of the worms was 3.4 mm (range, 0.7-11.3), and was greater in men with 2 or more nests (3.9 mm) than in those with only one nest (3.0 mm, P = 0.003). During the study period (2-35 months, mean, 13.7), lymphatic vessel diameter increased at the site of 92 (86.0%) adult worm nests. Mean rate of increase of lymphatic vessel diameter was 1.2 mm per person-year (range, 0-0.93 mm per month). In a general linear model, no factors, including treatment with antifilarial drugs, were significantly associated with rate of vessel diameter increase. Thus, lymphatic vessel dilatation progress in the presence of living adult W. bancrofti; the rate of this progression is heterogeneous. These data suggest that lymphatic dilatation will continue to progress in most infected persons even after mass treatment with currently recommended antifilarial drugs. In addition to interrupting transmission, the global programme for elimination of lymphatic filariasis should address the potential for disease progression in persons who remain infected with adult W. bancrofti.

Proposed panel of diagnostic criteria, including the use of ultrasound, to refine the concept of 'endemic normals' in lymphatic filariasis.

Summary Although living adult Wuchereria bancrofti worms can be detected by ultrasound examination of the scrotal area in approximately 80% of men infected with this filarial parasite, the location of the adult worms in the remaining 20% remains unclear. To determine this, 32 individuals who had W. bancrofti microfilaraemia but no adult worms detectable on ultrasound were treated with diethylcarbarmazine (DEC), either with a single 6 mg/kg dose (n = 13) or with a 12‐day course of 6 mg/kg per day (n = 19). They were then monitored with serial physical and ultrasound examinations. Thirteen (41%) subjects developed small, single scrotal nodules 12 h to 7 days after treatment; this rate was unaffected by the dose of DEC. No nodules were detected outside the scrotal area. All 5 men with lymphangiectasia suspected on ultrasound before treatment developed scrotal nodules, compared to 8 (29.6%) of 27 men without ultrasonographic evidence (P = 0.006). Thus, using both ultrasound and ‘provocative’ treatment with DEC, adult W. bancrofti can be detected in the scrotal area of an estimated 88% of infected men. Because no single diagnostic test for W. bancrofti infection is completely sensitive, a panel of tests, including ultrasound, is proposed to identify with greater accuracy ‘endemic normals’ for immunological and epidemiological studies.

Interdigital skin lesions of the lower limbs among patients with lymphoedema in an area endemic for bancroftian filariasis

Objectives  An estimated 15 million persons suffer from lymphoedema of the leg in filariasis‐endemic areas of the world. A major factor in the progression of lymphoedema severity is the incidence of acute dermatolymphangioadenitis (ADLA), which is triggered by bacteria that gain entry through damaged skin, especially in the toe web spaces (‘interdigital skin lesions’). Little is known about the epidemiology of these skin lesions or about patients’ awareness of them.

A Mechanism for Chronic Filarial Hydrocele with Implications for Its Surgical Repair

Background Chronic hydrocele is the most common manifestation of bancroftian filariasis, an endemic disease in 80 countries. In a prospective study, we evaluated the occurrence of intrascrotal lymphangiectasia, gross appearance/consistency of the testis, and the efficacy of complete excision of hydrocele sac in patients living in a bancroftian filariasis endemic area who underwent hydrocelectomy at the Center for Teaching, Research and Tertiary Referral for Bancroftian Filariasis (NEPAF). Methodology/Principal Findings A total of 968 patients with uni- or bilateral filarial hydrocele (Group-1) and a Comparison Group (CG) of 218 patients from the same area who already had undergone hydrocele-sac-sparing hydrocelectomy elsewhere were enrolled at NEPAF. Twenty-eight patients from the Comparison Group with hydrocele recurrence were re-operated on at NEPAF and constitute Group-2. In Group-1 a total of 1,128 hydrocelectomies were performed (mean patient age of 30.3yr and mean follow-up of 8.6yr [range 5.3–12]). The hydrocele recurrence rates in Group-1 and in the Comparison Group (mean age of 31.5 yr) were 0.3%, and 19.3%, respectively (p<0,001). There was no hydrocele recurrence in Group-2 (mean patient age of 25.1yr and mean follow-up of 6yr [range 5–6.9]). Per surgically leaking or leak-prone dilated lymphatic vessels were seen in the inner or outer surface of the hydrocele sac wall or in surrounding tissue, particularly in the retrotesticular area, in 30.9% and in 46.3% of patients in Group-1 and Group-2, respectively (p = 0.081). The testicles were abnormal in shape, volume, and consistency in 203/1,128 (18%) and 10/28 (35.7%) of patients from Group-1 and Group-2, respectively (p = 0,025). Conclusions/Significance Lymph fluid from ruptured dilated lymphatic vessels is an important component of chronic filarial hydrocele fluid that threatens the integrity of the testis in an adult population living in bancroftian filariasis endemic areas. To avoid hydrocele recurrence the authors advise complete excision of hydrocele sac and when identified, leaking or leak-prone dilated lymphatic vessels should be sutured or excised.

Dietilcarbamazina no tratamento da filariose bancroftiana

The authors presented a detailed review about the tratment of bancroftian filariasis with diethylcarbamazine. The interesting aspects about the drug discovery and the basic concepts about its pharmacology were reported in a summarised form. On the other hand, emphasis was made about the speculation done by several authors about the intringuing findings regarding its efficacy reported in the literature. Latter, it was brought the new advances about the disease, as for example, the visualization by ultrasound of living Wuchereria bancrofti adult worm on its natural host ¾ the human being. This made possible the comprehension of several paradoxical issues reported, focusing the treatment of infection using diethylcarbamazine. So far, because of the lack of ideal drug with micro and macrofilaricidal properties, together with the new understand about the disease and the new parameters for monitoring the efficacy of the drug, diethylcarbamazine has back its importance conquered at the begin of its discovery, almost fifth years ago.

Terapia complementar em área endêmica de filariose bancroftiana, pelos Clubes da Esperança

In 1997 the World Health Organization announced an ambitious project called the Global Program to Eliminate Lymphatic Filariasis, as a Public Health Problem. The program is based on two pillars: interruption of transmission and morbidity control. Experience in Recife, Brazil, an endemic area for bancroftian filariasis, showed that an innovative approach called Hope Clubs, can equip lymphedema patients with the skills, motivation, and enthusiasm to sustain effective, low-cost and convenient self-care to prevent acute skin bacterial episodes and milky urine in the case of chyluria carriers. They feel they are not alone, they regain their potential for productive work and are able to amplify these activities throughout filariasis-endemic communities.

Ultrastructural analysis of Wuchereria bancrofti (Nematoda: Filarioidea) body wall.

Bancroftian filariasis constitutes the principal mosquito-borne nematode infection of humans and the surface of adult of Wuchereria bancrofti seems to be especially important in the intricate interplay between host and parasite. The study of the parasites surface structure might help to understand the localization and function of various organelles. W. bancrofti adult worms were recovered from untreated patients during hydrocele repair surgery and studied by transmission electron microscopy. The body wall of adult parasite is composed of cuticle, hypodermis and muscular layer. Cuticle is the external layer and shows transverse cuticular striation. It is composed by an epicuticle, cortical layers, median layer, fibrous layers and basal layer. The epicuticle is the most external cuticular layer and appears as a single laminar electron-dense layer. The cortical external region is more electron-dense and granular in appearance than the inner cortical layer. Electron-dense structures, called bosses are randomly distributed filling the cuticular striation. The median layer is formed by an electron-dense and continuous thick line. The fibrous layer is subdivided in inner and external layers connected by projections. The basal layer includes a large quantity of membranous projections directed toward the hypodermis. The hypodermis is a syncytium where some cellular organelles are observed. The somatic musculature is meromyarian. The muscle fibers consist of contractile and non-contractile regions and the contractile region is composed of myofilaments separated by dense body. This is the first study of W. bancrofti adult worms obtained from untreated patients and studied by transmission electron microscopy.

A complexidade do custo socioeconômico da filariose linfática

Lack of knowledge of the socioeconomic impact of various diseases is generally one of the biggest obstacles to obtaining funds for investment in applied research and for starting to implement control programs that are needed in developing countries. The authors analyze and emphasize important aspects of the complexity of quantifying the socioeconomic impact of lymphatic filariasis. They highlight the gaps that exist within some fields of knowledge and that these gaps have still not been properly explored with regard to individuals with this disease. They bring together the data in the literature and echoes from their own experience gained through caring for patients with Bancroftian infection and disease at a tertiary referral service (NEPAF--Filariasis Care, Research and Teaching Center, Recife, Brazil). The social impact, in its broadest sense, consists of strong indications of losses of quality of life among patients. Unfortunately, this is still poorly documented and, up to a certain point, very difficult to quantify because of the very particular social abandonment of the endemic communities.