Bancroftian lymphadenopathy: a histopathologic study of fifty-eight cases from northeastern Brazil

Lymphatic filariasis: perspectives on lymphatic remodeling and contractile dysfunction in filarial disease pathogenesis

Lymphatic filariasis, one of the most debilitating diseases associated with the lymphatic system, affects over a hundred million people worldwide and manifests itself in a variety of severe clinical pathologies. The filarial parasites specifically target the lymphatics and impair lymph flow, which is critical for the normal functions of the lymphatic system in maintenance of body fluid balance and physiological interstitial fluid transport. The resultant contractile dysfunction of the lymphatics causes fluid accumulation and lymphedema, one of the major pathologies associated with filarial infection. In this review, we take a closer look at the contractile mechanisms of the lymphatics, its altered functions, and remodeling during an inflammatory state and how it relates to the severe pathogenesis underlying a filarial infection. We further elaborate on the complex host-parasite interactions, and molecular mechanisms contributing to the disease pathogenesis. The overall emphasis is on elucidating some of the emerging concepts and new directions that aim to harness the process of lymphangiogenesis or enhance contractility in a dysfunctional lymphatics, thereby restoring the fluid imbalance and mitigating the pathological conditions of lymphatic filariasis.

Bancroftian filariasis in children and adolescents: clinical–pathological observations in 22 cases from an endemic area

In areas where bancroftian filariasis is endemic, the clinical manifestations of the disease, which are often very varied, appear most frequently during early adulthood or later. In consequence, very little attention, if any, has been given to the signs and symptoms of the disease in childhood. In an attempt to fill this gap, clinical and pathological observations were made, in Brazil, on 22 children (aged 2-15 years) who were infected with Wuchereria bancrofti. There was a predominance of lymph-node involvement. In all but three (14%) of the children (who had adult parasites in their intrascrotal lymphatic vessels), the adult worms were located in the afferent or efferent vessels of draining lymph nodes, predominantly in the inguinal region. None of the patients presented with distal lymphoedema, and the adenopathy was characterized by painless, localized, lymph-node enlargement, without signs of inflammation in the overlying skin. Histologically, the alterations in the lymphatic vessels and surrounding structures were similar to those described in adult patients, and depended essentially on adult-parasite viability. The localization of the adult worms in the paediatric cases was peculiar and distinct from that observed in adult patients, in whom the adult parasites are usually found in extra-nodal lymphatic vessels. In areas endemic for bancroftian filariasis, therefore, filarial infection should be considered as a possible cause of adenopathy. For the differential diagnosis of adenopathy in young patients from endemic areas, the authors recommend the use of ultrasound and other non-invasive diagnostic tools, as alternatives to excisional biopsies, which are often unnecessary in bancroftian filariasis.

Helminth infection in populations undergoing epidemiological transition: a friend or foe?

Helminth infections are highly prevalent in developing countries, especially in rural areas. With gradual development, there is a transition from living conditions that are dominated by infection, poor sanitation, manual labor, and traditional diet to a situation where burden of infections is reduced, infrastructure is improved, sedentary lifestyle dominates, and processed food forms a large proportion of the calorie intake. The combinations of some of the changes in lifestyle and environment are expected to result in alteration of the landscape of diseases, which will become dominated by non-communicable disorders. Here we review how the major helminth infections affect a large proportion of the population in the developing world and discuss their impact on the immune system and the consequences of this for other infections which are co-endemic in the same areas. Furthermore, we address the issue of decreasing helminth infections in many parts of the world within the context of increasing inflammatory, metabolic, and cardiovascular diseases.

Lymphatic filariasis in children: clinical features, infection burdens and future prospects for elimination

Lymphatic filariasis (LF), a common parasitic infection in tropical countries, causes lymphoedema of limbs, hydrocele and acute attacks of dermato-lymphangio-adenitis. Recent advances in diagnosis have helped to recognize that LF infection is often acquired in childhood. Newly available diagnostic techniques like sensitive antigen and antibody assays, Doppler ultrasonography and lymphoscintigraphy have helped to understand the subclinical pathology caused by this infection, which was hitherto generally believed to be irreversible. Recent studies indicate that drugs used in the mass drug administration (MDA) programme under GPELF are capable of reversing the sub-clinical lymphatic damage in children and provide benefits other than interruption of transmission. Albendazole and ivermectin used in MDA are effective against soil-transmitted helminthic infections common in children in LF endemic areas. Thus MDA had other 'beyond LF' benefits in treated children including increased appetite, weight gain, greater learning ability and concentration, better school attendance and prevention of anaemia. MDA should no longer be viewed as a measure for interrupting transmission alone. Recent findings of reversibility of early lymphatic pathology in treated children indicate that both MDA and 'foot-hygiene' measures are effective strategies in preventing and managing morbidity. Programme managers should effectively utilize this information to strengthen their advocacy efforts to achieve high and sustainable coverage in MDA.

Lymphatics, tertiary lymphoid organs and the granulomas of Crohn's disease: an immunohistochemical study

BACKGROUND

Case studies in the past repeatedly suggested that the fundamental alteration in Crohn's disease occurs in the regional lymphatics of the intestine.

AIM

To evaluate the lymphatic inflammation in Crohn's disease, and to characterise lymphoid aggregates and granulomas in and surrounding lymphatics and blood vasculature.

METHODS

Forty-eight tissue blocks from 24 Crohn's disease patients and 23 tissue blocks from 23 control patients were selected. Tissue sections were immunostained with a lymphatic endothelial cell marker (D2-40), a marker for blood vasculature (FVIII), and markers for T cells (CD3), B cells (CD20) and macrophages (CD68).

RESULTS

Lymphangiectasia and lymphocytic perilymphangitis were demonstrated in all 24 patients, lymphocyte-obstructed lymphatics in seven patients, granuloma-obstructed lymphatics in nine patients and inflammatory lymphoid follicles in all 24 patients. Free-standing granulomas occurred in 19 patients, and in three further patients granulomas were in or attached to blood vascular units.

CONCLUSIONS

This study, employing immunohistochemistry, revealed, better than standard microscopy, the association of inflammation, granulomas and tertiary lymphoid follicles or organs with the lymphatic vasculature in Crohn's disease. Disease in some patients was characterised by perilymphangitis and lymphoid follicular inflammation and in others by granulomas, some of which totally obstructed lymphatics. These findings have aetiological, therapeutic and prognostic implications.

Lymphatics in human lymphatic filariasis: in vitro models of parasite-induced lymphatic remodeling

Lymphatic filariasis characterized by the dysfunction of the lymphatics can lead to severe (and often) irreversible lymphedema and elephantiasis. Decades of research in the field shows that the establishment of the adult parasites in the lymphatics triggers a cascade of events that ultimately results in tissue scarring and fibrosis. In this minireview, we focus on the studies addressing the mechanisms underlying the parasite-induced lymphatic dilatation that suggests parasite-induced lymphatic remodeling and lymphangiogenesis may be the prelude towards developing chronic and irreversible filarial pathology.

Filariasis and lymphoedema

Among the causes of lymphoedema (LE), secondary LE due to filariasis is the most prevalent. It affects only a minority of the 120 million people infected with the causative organisms of lymphatic filariasis (LF), Wuchereria bancrofti and Brugia malayi/timori, but is clustered in families, indicating a genetic basis for development of this pathology. The majority of infected individuals develop filarial-specific immunosuppression that starts even before birth in cases where mothers are infected and is characterized by regulatory T-cell responses and high levels of IgG4, thus tolerating high parasite loads and microfilaraemia. In contrast, individuals with this pathology show stronger immune reactions biased towards Th1, Th2 and probably also Th17. Importantly, as for the aberrant lymph vessel development, innate immune responses that are triggered by the filarial antigen ultimately result in the activation of vascular endothelial growth factors (VEGF), thus promoting lymph vessel hyperplasia as a first step to lymphoedema development. Wolbachia endosymbionts are major inducers of these responses in vitro, and their depletion by doxycycline in LF patients reduces plasma VEGF and soluble VEGF-receptor-3 levels to those seen in endemic normals preceding pathology improvement. The search for the immunogenetic basis for LE could lead to the identification of risk factors and thus, to prevention; and has so far led to the identification of single-nucleotide polymorphisms (SNP) with potential functional relevance to VEGF, cytokine and toll-like receptor (TLR) genes. Hydrocele, a pathology with some similarity to LE in which both lymph vessel dilation and lymph extravasation are shared sequelae, has been found to be strongly associated with a VEGF-A SNP known for upregulation of this (lymph-)angiogenesis factor.

Lymphangiogenesis and lymphatic remodeling induced by filarial parasites: implications for pathogenesis

Even in the absence of an adaptive immune system in murine models, lymphatic dilatation and dysfunction occur in filarial infections, although severe irreversible lymphedema and elephantiasis appears to require an intact adaptive immune response in human infections. To address how filarial parasites and their antigens influence the lymphatics directly, human lymphatic endothelial cells were exposed to filarial antigens, live parasites, or infected patient serum. Live filarial parasites or filarial antigens induced both significant LEC proliferation and differentiation into tube-like structures in vitro. Moreover, serum from patently infected (microfilaria positive) patients and those with longstanding chronic lymphatic obstruction induced significantly increased LEC proliferation compared to sera from uninfected individuals. Differentiation of LEC into tube-like networks was found to be associated with significantly increased levels of matrix metalloproteases and inhibition of their TIMP inhibitors (Tissue inhibitors of matrix metalloproteases). Comparison of global gene expression induced by live parasites in LEC to parasite-unexposed LEC demonstrated that filarial parasites altered the expression of those genes involved in cellular organization and development as well as those associated with junction adherence pathways that in turn decreased trans-endothelial transport as assessed by FITC-Dextran. The data suggest that filarial parasites directly induce lymphangiogenesis and lymphatic differentiation and provide insight into the mechanisms underlying the pathology seen in lymphatic filariasis.

The nematode parasites Brugia malayi and Wuchereria bancrofti are the major organisms responsible for lymphatic filariasis. Lymphatic filariasis is characterized by the dysfunction of the lymphatics that can lead to severe (and often) irreversible lymphedema and elephantiasis. Current advances in distinguishing blood vascular from lymphatic endothelial cells have allowed the direct study of the interaction between live filarial parasites and their lymphatic niche. In the quest towards understanding parasite-lymphatic endothelium interactions, we observed that the filarial antigens have a specific but differential stimulatory capacity towards the lymphatics and cause them to differentiate into tube-like vascular networks in vitro that resemble the formation of collateral lymphatics in vivo. This was a lymphatic-specific phenomenon, as the filarial parasites or antigen did not exhibit similar effects on the human umbilical vein endothelial cells. The differentiation of the lymphatic endothelial monolayers into vascular networks was not dependent on typical markers of lymphangiogenesis but rather involves the matrix metalloproteases and their inhibitors that suggest lymphatic matrix remodeling rather than rendering of the lymphatics hyper-permeable as has been postulated previously.

Micronutrient status indicators in individuals single- or double-infected with HIV and Wuchereria bancrofti before and after DEC treatment

OBJECTIVE

To identify possible associations between selected micronutrient status indicators (serum ferritin, retinol, beta-carotene, alpha-tocopherol, and the acute phase reactant alpha-1 antichymotrypsin) and infection with human immunodeficiency virus (HIV) or Wuchereria bancrofti, and to assess the effect of the antifilarial drug diethylcarbamazine (DEC) on the micronutrient status indicators in individuals positive for one or both of the two infections.

METHODS

Serum concentrations of ferritin, retinol, beta-carotene, alpha-tocopherol and the acute phase reactant alpha-1 antichymotrypsin were examined in 59 individuals with HIV, W. bancrofti infection, or both, in Tanga Region, Tanzania, before and 12 weeks after treatment with DEC.

RESULTS

HIV infection, but not W. bancrofti infection, was associated with higher serum ferritin concentrations and lower beta-carotene and alpha-tocopherol. Neither HIV infection nor W. bancrofti infection was associated with serum retinol. The four micronutrient status indicators and alpha-1 antichymotrypsin were generally lower at 12 weeks after treatment both in the DEC and the placebo groups.

CONCLUSIONS

The negative association between HIV infection and the antioxidant vitamins beta-carotene and alpha-tocopherol may be due to infection-induced oxidative stress, whereas W. bancrofti infection seemed not to be associated with oxidative stress. The drop in antioxidant vitamin concentrations after treatment may be due to oxidative stress induced by HIV progression (HIV infected) and inflammation around dead adult worms and microfilariae (W. bancrofti infected) rather than to an effect of DEC.

Chronic clinical manifestations related to Wuchereria bancrofti infection in a highly endemic area in Kenya

Clinical examinations were conducted in an effort to provide baseline data for a pilot filariasis elimination programme implemented in a Wuchereria bancrofti-endemic focus in Malindi district, Kenya. Of 186 males aged 15 years and above examined, 64 individuals (34.4%) had hydrocele, and the prevalence of the manifestation in those above 40 years old was 55.3%. The prevalence of leg lymphoedema in persons aged 15 years and above was 8.5%, with a higher rate in males (12.6%) than in females (5.7%). The overall prevalence of inguinal adenopathy was 8.6%, and males had a significantly higher (12.9%) prevalence of adenopathy than females (5.1%) (P<0.001). The data in the present study provided support for consideration of filarial infection as a possible cause of inguinal lymphadenopathy in bancroftian filariasis-endemic areas. The results of this study also indicate that lymphatic filariasis is a serious public health problem in the northern coastal areas and morbidity control programmes should be implemented to alleviate the suffering of those affected.

Lymphadenovarix in the axilla--an unusual presentation of filariasis

Clinical manifestations of lymphatic filariasis depend on the area of lymphatic involvement and the duration of infection. A 21 year old man, resident in a filariasis endemic region, presented with multiple matted lymph nodes with cystic areas forming a large mass in his left axilla. An ultrasound scan of the axilla using a 7.5 MHz transducer revealed grossly dilated lymphatics but no filarial dance sign. Fine needle (21 G) aspiration cytology (FNAC) from the dilated lymphatics and solid areas in the lymph node mass revealed multiple microfilariae in a background of reactive lymphoid cells. Peripheral blood smears revealed microfilaremia with significant eosinophilia. Diagnosis of left axillary Bancroftian lymphadenovarix was made. On the administration of oral diethylcarbamazine, the diameter of the lymphatic vessels in the lymphadenovarix reduced considerably in size and microfilaremia disappeared. We report this case because axillary lymphadenovarix is a rare presentation of filariasis. This case is also unique since microfilariae were demonstrated in the fluid aspirated from the dilated lymphatics of the lymphadenovarix in the absence of live adult worms.

Detection of lymphatic Wuchereria bancrofti in carriers and long-term storage blood samples using semi-nested PCR

The semi-nested PCR was conducted for detection of Wuchereria bancrofti in patients' blood. The primers were designed based on the repetitive DNA sequences of the parasite. The results demonstrated that the semi-nested PCR could detect as little as 0.001 fg of parasite DNA. In addition, the primers showed no PCR amplification from human and other hemoparasites such as Brugia malayi, Plasmodium falciparum and P. vivax DNAs. This technique was used for detection of 18 W. bancrofti infected blood samples with a long-term storage, the data revealed that all samples were positive. The results obtained from this study clearly indicated that the semi-nested PCR is specific, sensitive, and suitable for detection of the disease carriers.

Toward an understanding of the interaction between filarial parasites and host antigen-presenting cells

Lymphatic filarial infection, from an immunologic point of view, is one of the most complex parasite infections. Not only are there different clinical manifestations that reflect differing immune responses, but the parasite's multiple stages, each with distinct anatomic tropism, add a compartmental layer of complexity to an already complicated process. Moreover, these parasites have finely tuned immune evasion strategies that enable escape from the innate immune system. As different stages of the parasite interact with different types of antigen-presenting cells that, in turn, may play a significant role in shaping the subsequent adaptive immune response, the focus of this review is to provide insight into the interaction between filarial parasites and antigen-presenting cells with an eye toward understanding how they influence parasite antigen-driven T-cell responses.

Inflammatory antigens of Brugia malayi and their effect on rodent host Mastomys coucha

The study was aimed at identifying pro- and anti-inflammatory cytokine releasing potential of Brugia malayi adult worm fractions and their role in filarial infection and pathogenesis. THP-1 cells were incubated with soluble somatic Brugia malayi adult worm extract (BmAS) and its Sephadex G-200 fractions BmAFI, BmAFII and BmAFIII and the effect of the fractions on parasitological, immunological and lymph node parameters was assessed in Mastomys coucha. BmAFII stimulated the pro-inflammatory TNF-alpha, IL-1beta and IL-6 release; IL-10 release was insignificant. Sensitization of animals with BmAFII and subsequent intraperitoneal implantation of worms enhanced CMI response. BmAFII also increased lymph node weight and cellularity, stimulated lymph node mast cells and eliminated intraperitoneally instilled worms. BmAFI stimulated several folds more release of IL-10, whereas TNF-alpha release was negligible. Sensitization with BmAFI elicited low CMI responses, moderately stimulated mast cells and facilitated survival of implanted adult parasites. Fifty percent of naive animals exposed to BmAFI showed oedematous lymph nodes and increased node weight. NCP-bound molecules corresponding to BmAFI and II showed cytokine-stimulating potential in vitro. It is concluded that BmAFII is protective and stimulates pro-inflammatory cytokines, whereas BmAFI facilitates parasite survival and stimulates IL-10.

A produção do conhecimento científico e as políticas de saúde pública: reflexões a partir da ocorrência da filariose na cidade do Recife, Pernambuco, Brasil

O artigo discute a relação entre a produção científica sobre a ocorrência da filariose bancroftiana no Brasil e o processo de formulação e implementação da política de saúde voltada ao seu controle. Para tanto, realiza uma revisão da produção do conhecimento e das políticas específicas, no período compreendido desde a criação do Programa de Combate à Filariose, em meados do século passado, até a criação do SUS, no marco da descentralização do controle das endemias. Centrando suas observações empíricas na ambiência da cidade do Recife, espaço urbano no qual ainda prevalece a filariose, ressalta os processos institucionais e destaca o papel dos distintos atores neles envolvidos. Partindo da hipótese de que se até à primeira metade do século vinte faltavam o conhecimento científico e o desenvolvimento tecnológico para o controle do problema, a seguir, quando esses avanços são disponibilizados, outros requerimentos, agora do campo da política, irão se impor, atuando como determinantes da persistência da endemia na cidade.

The histopathology of bancroftian filariasis revisited: the role of the adult worm in the lymphatic-vessel disease

Although morphology is generally limited to static images, the histopathological features of bancroftian lymphatic disease are presented here in a way that is as dynamic as possible and closely associated with the clinical, ultrasonographic and surgical characteristics. The protean spectrum of alterations seen in the host's lymphatic vessels is discussed, and the changes caused by the live and dead worms are highlighted, as independent events. Evidence of a remodelling process, in which the lymphatic endothelial cells appear to have a key role, is provided for the first time. Despite many new pieces of information, there remain many 'blank pages' in the natural history of bancroftian filariasis.

Lymphatic filariasis-specific immune responses in relation to lymphoedema grade and infection status. I. Cellular responses

The filariasis-specific cellular responsiveness was assessed in 109 adult individuals from a Wuchereria bancrofti-endemic area in north-east Tanzania. There were 9 study groups. Five groups of individuals were negative for microfilariae (mf) and specific circulating filarial antigen (CFA) and had leg lymphoedema of varying severity ranging from early to more advanced grades (pathology groups 1-5). Another group comprised individuals with mixed grades of lymphoedema and positive for mf and/or CFA (mixed pathology group). Three asymptomatic groups consisted of individuals without leg pathology but with different infection status: (i) CFA- and mf-negative individuals, (ii) CFA-positive but mf-negative individuals, and (iii) CFA- and mf-positive individuals. Peripheral blood mononuclear cells were collected and proliferative responsiveness and secretion of interleukin (IL)-4, IL-10 and gamma interferon (IFN gamma) were measured upon stimulation with a Brugia pahangi antigen. No distinct differences in responses were observed between the 5 uninfected pathology groups. Instead, responses were associated with infection status, with generally higher proliferative activity and higher levels of IL-4 and IFN gamma in uninfected as compared to infected individuals. High levels of IL-10 were observed in asymptomatic individuals without infection and in asymptomatic CFA-positive but mf-negative individuals. Asymptomatic individuals with mf had relatively low IL-10 levels. Groups presenting with chronic pathology generally had low levels of IL-10 independently of infection status. The findings thus give no immediate indication that the measured immunological parameters are related to progression of leg pathology. However, alternative interpretations are presented which suggest a possible role of immunological reactions in development of pathology in lymphatic filariasis.

A randomized, double-blind, placebo-controlled study with diethylcarbamazine for the treatment of hydrocoele in an area of Tanzania endemic for lymphatic filariasis

Hydrocoele is common in men in Wuchereria bancrofti-endemic areas, the treatment for which is currently surgical intervention. Two community studies have recently suggested that the antifilarial drug diethylcarbamazine (DEC) may have a beneficial effect of reducing the size of hydrocoeles of filarial origin. To test this hypothesis, a double-blind, placebo-controlled study was carried out in 1998 and 1999 in an area of north-eastern Tanzania where microfilaria (mf) carrier rates and hydrocoele prevalence rates were known to be high. Ninety-eight adult male volunteers (aged > or = 15 years) with chronic hydrocoele received DEC 300 mg per day for 12 days (49 patients), or placebo (49 patients). Circumferential and ultrasonographic measurements of the scrotum, and a serum sample for measuring W. bancrofti antigen, were obtained at the onset and after 3, 6 and 12 months. Scrotal size and hydrocoele fluid volume indices were calculated. No statistically significant differences in volumetric measurements between the DEC and placebo groups were found at any of the follow-ups. Separate analyses dividing patients by antigen status, hydrocoele size or presence of thickening of the scrotal skins gave similar results. Geometric mean intensity of W. bancrofti antigen was significantly lower in the DEC group than in the placebo group (P = 0.008), indicating that lack of compliance was not a significant factor. Two months into the treatment trial, mass treatment with monthly low-dose DEC was given to the rest of the community. We conclude that DEC is not effective in reducing the size of hydrocoele of filarial origin. Interventions to replace or supplement hydrocoelectomy should be investigated.

Lymphatic filariasis: an infection of childhood

Lymphatic filariasis (LF), already recognized as a widespread, seriously handicapping disease of adults, was generally thought to occur only sporadically in children. New, highly sensitive diagnostic tests (antigen detection, ultrasound examination) now reveal, however, that LF is first acquired in childhood, often with as many as one-third of children infected before age 5. Initial damage to the lymphatic system by the parasites generally remains subclinical for years or gives rise only to non-specific presentations of adenitis/adenopathy; however, especially after puberty the characteristic clinical features of the adult disease syndromes (lymphoedema, hydrocoele) manifest themselves. Recognizing that LF disease starts its development in childhood has immediate practical implications both for management and prevention of the disease in individual patients and for the broader public health efforts to overcome all childhood illnesses. For the new World Health Organization (WHO)-supported, public-/private-sector collaboration (Global Alliance) to eliminate LF through once-yearly drug treatment, this recognition means that children will be not only the principal beneficiaries of LF elimination but also a population particularly important to target in order for the programme to achieve its twin goals of interrupting transmission and preventing disease.

Divergent roles for macrophages in lymphatic filariasis

Macrophages have long been recognized as important cells associated with filarial infection but their function as effectors and/or suppressors has not been elucidated. Recent advances in our understanding of the role that macrophages may play in lymphatic filariasis have come from in vitro studies and mouse models of filarial infection. Based on these new findings, we hypothesize that while dead or dying worms induce the 'classical' activation of macrophages and a subsequent pro-inflammatory response, live and healthy worms secrete products that induce type 2 cytokines and the differentiation of 'alternatively' activated macrophages that downregulate an inflammatory response. Thus, the balance between the 'classical' and 'alternative' activation pathways of macrophages could be an important factor in inflammatory pathology associated with filariasis.

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.

Histopathological, lymphoscintigraphical, and immunological changes in the inguinal lymph nodes of rhesus monkeys during the early course of infection with Brugia malayi

The relationship of the early lymphatic pathophysiological alterations with those of tissue inflammatory and cellular responses in the inguinal lymph nodes of Brugia malayi-infected rhesus monkeys was examined. Each of five animals was inoculated subcutaneously in the right calf with 200 third stage larvae (L3) and 5 weeks later, before the onset of patency [10 to 12 weeks postinoculation (PI)], their right inguinal nodes began to show signs of enlargement, becoming most prominent between weeks 10 to 16 PI. Histopathologically, the right nodes had eosinophilic lymphadenitis, lymphoid hyperplasia, and pronounced germinal centers. Lymphoscintigraphy using 99mTc-antimony trisulfide colloid showed pathophysiological alterations of the lymph flow rate in the right leg but not in the left leg at weeks 7 and 15 PI. In vitro blastogenesis to B. malayi antigens at week 10 PI showed the inguinal lymph node cells proliferated more vigorously than did peripheral blood cells early in infection. However, at week 24 PI both lymph node and peripheral blood cells proliferated to antigens. Flow cytometry showed an upregulation of HLA-DR+ lymphocytes in right lymph node cells from infected animals when compared to those from control animals. No changes in CD2, CD4, CD8, CD20, CD29, and CD45R cell numbers in lymph node of infected animals were seen when compared to control animals. Our results show that lymphatic pathology occurs early before the onset of patency, correlating with a marked tissue inflammatory and cellular responses of lymph node cells in B. malayi-infected rhesus monkeys. The rhesus could be an extremely useful model for understanding the evolution of pathology and pathogenesis of the disease.

Requirement for In Vivo Production of IL-4, But Not IL-10, in the Induction of Proliferative Suppression by Filarial Parasites

Loss of T lymphocyte proliferation and the emergence of a host response that is dominated by a Th2-type profile are well-established features of human filariasis. We have previously reported that adherent peritoneal exudate cells (PEC) from mice transplanted with adult Brugia malayi parasites suppress the proliferation of lymphocytes without blocking Ag-cytokine production in vitro. We now show that infection of mice with the infective larval (L3) stage of B. malayi generates a similar population of PEC. Suppressive cells are generated within 7 days of infection and mediate their effects through a nitric oxide-independent pathway. Both L3 and adult infection elicit high levels of host IL-4 whereas the microfilarial stage of the parasite induces IFN-γ production and does not generate a similar form of suppression. Production of host IL-4 was necessary to allow the generation of suppressive PEC, given that IL-4-deficient mice implanted with adult parasites failed to induce proliferative block. However, IL-10-deficient mice implanted with adult parasites resulted in T cell suppression, indicating that IL-10 is not essential for the induction of hyporesponsiveness. Neither IL-4 nor IL-10 were directly responsible for ablating cellular proliferation in vitro, as the addition of neutralizing Ab to either cytokine did not reverse the proliferative block. Thus, IL-4 produced in vivo in response to filarial L3 and adult parasites is essential for the induction of proliferative suppression but is not itself the suppressive factor.

Requirement for In Vivo Production of IL-4, But Not IL-10, in the Induction of Proliferative Suppression by Filarial Parasites

Loss of T lymphocyte proliferation and the emergence of a host response that is dominated by a Th2-type profile are well-established features of human filariasis. We have previously reported that adherent peritoneal exudate cells (PEC) from mice transplanted with adult Brugia malayi parasites suppress the proliferation of lymphocytes without blocking Ag-cytokine production in vitro. We now show that infection of mice with the infective larval (L3) stage of B. malayi generates a similar population of PEC. Suppressive cells are generated within 7 days of infection and mediate their effects through a nitric oxide-independent pathway. Both L3 and adult infection elicit high levels of host IL-4 whereas the microfilarial stage of the parasite induces IFN-γ production and does not generate a similar form of suppression. Production of host IL-4 was necessary to allow the generation of suppressive PEC, given that IL-4-deficient mice implanted with adult parasites failed to induce proliferative block. However, IL-10-deficient mice implanted with adult parasites resulted in T cell suppression, indicating that IL-10 is not essential for the induction of hyporesponsiveness. Neither IL-4 nor IL-10 were directly responsible for ablating cellular proliferation in vitro, as the addition of neutralizing Ab to either cytokine did not reverse the proliferative block. Thus, IL-4 produced in vivo in response to filarial L3 and adult parasites is essential for the induction of proliferative suppression but is not itself the suppressive factor.

[Diethylcarbamazine in the treatment of Bancroft's filariasis]

The authors presented a detailed review about the treatment 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 intriguing 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--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.

Evaluation of the Og4C3 ELISA in Wuchereria bancrofti infection: infected persons with undetectable or ultra-low microfilarial densities

The recently developed Og4C3 ELISA, which detects circulating Wuchereria bancrofti antigen, appears promising for use in epidemiological surveys, but its sensitivity is unknown in persons with ultra-low microfilarial densities. We used the Og4C3 to test the sera of 282 persons who were microfilaria-positive in 1-16 ml of blood, 18 persons who were microfilaria-negative but who had ultrasonographic or biopsy evidence of adult W. bancrofti infection, and 63 lifelong residents of a non-endemic area of Brazil. A total of 276 (97.9%) persons with detectable microfilaraemia tested positive (optical density > 0.033). At microfilarial densities of < 1, 1-30, and > 30 microfilariae per ml of blood, the sensitivity of the Og4C3 was 72.2, 97.6 and 100%, respectively (chi 2-test for trend, P < 10(-6)). The assay was positive in 66.7% of amicrofilaraemic persons with evidence of adult worm infection and in one (1.6%) of 63 residents of the non-endemic area (specificity, 98.4%). Our findings support the increasingly widespread use of the Og4C3 for field investigations and epidemiological assessments. However, the sensitivity of the assay may be low in persons who are microfilaria-negative or with densities of < 1 microfilaria per ml.

Histological evidence for adulticidal effect of low doses of diethylcarbamazine in bancroftian filariasis

The ability of diethylcarbamazine (DEC) to kill adult Wuchereria bancrofti worms was evaluated by examining lymphatic nodules formed after treatment with 4 different treatment schedules of 193 males living in the endemic area of Greater Recife, Brazil. Lymphatic nodules appeared in the spermatic cord or upper extremities in 43 of 138 microfilaraemic individuals, in 3 of 30 amicrofilaraemic patients with filarial disease manifestations, and in 1 of 25 asymptomatic amicrofilaraemic residents of the endemic area treated with DEC. Fourteen of these nodules were surgically removed 10-150 d after the start of treatment. Regardless of the DEC dosage and schedule used, all nodules contained damaged and degenerating adult worms. An exuberant granulomatous process with large numbers of eosinophils and progressive fibrosis gradually developed around the dead parasites. The mechanism(s) by which DEC killed adult W. bancrofti could not be determined.

Occurrence of living adult Wuchereria bancrofti in the scrotal area of men with microfilaraemia

To determine the frequency with which living adult Wuchereria bancrofti can be detected by ultrasound in the scrotal area of men with filarial infection, we used a 7.5 MHz transducer to perform weekly ultrasound examinations on 100 microfilaraemic men (18-34 years old) from Greater Recife, Brazil. The peculiar pattern of movement that characterizes the adult worm image on ultrasound (the filaria dance sign) was detected in the lymphatic vessels of the spermatic cord in 80 men (bilaterally in 29 men). Among 20 men with no filaria dance sign, the geometric mean microfilarial density was 68/mL, compared with 238/mL and 775/mL among those with unilateral and bilateral filaria dance signs, respectively (P = 0.0001). The lymphatic vessels of the spermatic cord appear to be a common, and perhaps the principal, site of adult W. bancrofti in men with asymptomatic microfilaraemia. Studies are needed to define the relationship between the presence of filarial worms in the scrotal area and the development of filaria-associated morbidity.

No relationship between HTLV-1 infection and filariasis--Serological study on patients with filariasis in Recife, Brazil

The seroprevalence of antibodies against human T-cell leukemia virus was determined by ELISA in 68 patients with filarial infestation living in an endemic area. The total seropositivity was 2.9% and the HTLV-1-positive cases were detected in 2 microfilaremic patients 12 and 40 years old. This value is very close to that obtained for healthy individuals in the same region and age groups. This result suggests that there is no relationship between filariasis and HTLV-1 infection as previously proposed.

A typical presentation of a parasitic infestation mimicking a metastatic carcinoma

A case of ectopic filarial infestation mimicking metastatic oesophageal carcinoma is presented. The clinical implications, pathologic features and pathogenesis of this atypical presentation are discussed.

Lymphatic filariasis: diagnosis and pathogenesis. WHO expert committee on filariasis

In the past few years, knowledge of many aspects of lymphatic filariasis, s debilitating disease with serious economic and social consequences, has increased. This article presents sections on diagnosis, pathogenesis, immunopathology and protective immunity from the recently published Expert Committee's report.