Episodic adenolymphangitis and lymphoedema in patients with bancroftian filariasis

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

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 PlusMinus; 18.8 ml) to day 360 (71.8 PlusMinus; 20.7 ml) compared to the pre-treatment (day 0, 198.4 PlusMinus; 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.

Impact on the quality of life of lymphoedema patients following introduction of a hygiene and skin care regimen in a Guyanese community endemic for lymphatic filariasis: A preliminary clinical intervention study

BACKGROUND: Hygiene and skin care are effective and important interventions in the management of lymphoedema secondary to lymphatic filariasis. We analyzed the impact on the quality of life that education and introduction of a designated nurse had on lymphoedema patients in a community that was endemic for lymphatic filariasis. METHODS: Patients' life quality was assessed using a Dermatology Life Quality Index (DLQI) questionnaire. At the same time they received education on appropriate hygiene, skin care techniques and simple exercises that encourage lymph drainage. A designated nurse was provided with educational materials and treatments. The DLQI life quality measure was repeated one year later. RESULTS: The DLQI improved for all patients and reported acute attacks were reduced. A paired t-test showed the improvement in DLQI to be highly significant (P = < 0.0001). CONCLUSIONS: A nurse-led service combined with patient education in communities endemic for lymphatic filariasis is an effective intervention in improving the quality of life of patients with lymphoedema.

Preadult stage parasites and multiple timed exposure to infective larvae are involved in development of limb edema in Brugia malayi-infected Indian leaf monkeys (Presbytis entellus)

The pathogenesis of filarial limb edema is not known. The role of parasitological variables and parasite-mediated phenomena in the development of limb edema was investigated in the Presbytis entellus-Brugia malayi model. Infection was initiated with subcutaneous inoculation of infective third-stage larvae (L(3)), and the animals were reexposed to different doses of L(3) at the prepatent, patent, and diminishing microfilaremia (0 to 5% of peak microfilaremia count) stages of infection. A large L(3) inoculum size and repeated inoculation in the ankle region during the prepatent, patent, and diminishing microfilaremia stages of infection were found to be necessary for reproducible induction of limb edema. The preadult stage of the parasite was found to be the most potent inducer of limb edema, followed by L(5) and L(4). The presence of the proinflammatory cytokines tumor necrosis factor alpha, interleukin-1beta, and interleukin-6 in edema fluid in the leg receiving the parasite challenge indicated that the limb edema development was due to parasite-mediated cytokine responses. The absence of bacterial infection or anti-streptolysin O titer in the edema fluid and blood indicated that bacterial infection is not necessary for the development of limb edema.

Lymphatic filariasis of the ovary and mesosalpinx

We report 2 cases of filariasis, one in the ovary and the other in the mesosalpinx. In the first case, the patient underwent panhystrectomy and in the second case, right ovarian cystectomy with right salpingectomy were performed under general anaesthesia. Histopathology showed adult filarial worms in the dilated lymphatics of the right ovary, in the first case and in the mesosalpinx, in the second case. Both patients presented with complaints related to gynecological problems and not filariasis. Reports of filariasis in the literature and possible treatments and prevention strategies are also discussed.

Transmission intensity and the immunoepidemiology of bancroftian filariasis in East Africa

Previous attempts to determine the interactions between filariasis transmission intensity, infection and chronic disease have been limited by a lack of a theoretical framework that allows the explicit examination of mechanisms that may link these variables at the community level. Here, we show how deterministic mathematical models, in conjunction with analyses of standardized field data from communities with varying parasite transmission intensities, can provide a particularly powerful framework for investigating this topic. These models were based on adult worm population dynamics, worm initiated chronic disease and two major forms of acquired immunity (larval- versus adult-worm generated) explicitly linked to community transmission intensity as measured by the Annual Transmission Potential (ATP). They were then fitted to data from low, moderate and moderately high transmission communities from East Africa to determine the mechanistic relationships between transmission, infection and observed filarial morbidity. The results indicate a profound effect of transmission intensity on patent infection and chronic disease, and on the generation and impact of immunity on these variables. For infection, the analysis indicates that in areas of higher parasite transmission, community-specific microfilarial rates may increase proportionately with transmission intensity until moderated by the generation of herd immunity. This supports recent suggestions that acquired immunity in filariasis is transmission driven and may be significant only in areas of high transmission. In East Africa, this transmission threshold is likely to be higher than an ATP of at least 100. A new finding from the analysis of the disease data is that per capita worm pathogenicity could increase with transmission intensity such that the prevalences of both hydrocele and lymphoedema, even without immunopathological involvement, may increase disproportionately with transmission intensity. For lymphoedema, this rise may be further accelerated with the onset of immunopathology. An intriguing finding is that there may be at least two types of immunity operating in filariasis: one implicated in anti-infection immunity and generated by past experience of adult worms, the other involved in immune-mediated pathology and based on cumulative experience of infective larvae. If confirmed, these findings have important implications for the new global initiative to achieve control of this disease.

Wolbachia bacteria in filarial immunity and disease

Lymphatic filarial nematodes are infected with endosymbiotic Wolbachia bacteria. Lipopolysaccharide from these bacteria is the major activator of innate inflammatory responses induced directly by the parasite. Here, we propose a mechanism by which Wolbachia initiates acute inflammatory responses associated with death of parasites, leading to acute filarial lymphangitis and adverse reactions to antifilarial chemotherapy. We also speculate that repeated exposure to acute inflammatory responses and the chronic release of bacteria, results in damage to infected lymphatics and desensitization of the innate immune system. These events will result in an increased susceptibility to opportunistic infections, which cause acute dermatolymphangitis associated with lymphoedema and elephantiasis. The recognition of the contribution of endosymbiotic bacteria to filarial disease could be exploited for clinical intervention by the targeting of bacteria with antibiotics in an attempt to reduce the development of filarial pathology.

Acute adenolymphangitis due to bancroftian filariasis in Rufiji district, south east Tanzania

A longitudinal prospective surveillance for acute adenolymphagitis (ADL) was carried out in three villages in Rufiji district. A sample population of 3000 individuals aged 10 years and above was monitored fortnightly for a period of 12 months. The annual incidence of ADL was found to be 33 per 1000 population and was significantly higher in males than females (52.7/1000 and 18.7/1000 respectively). ADL episodes were more frequent in the age group of 40 years and above. Individuals with chronic manifestations seemed to be more vulnerable to ADL attacks with 62.2% of the total episodes occurring in this group. Furthermore, individuals with lymphoedema experienced more frequent acute episodes compared to those with hydrocele and 'normal exposed'. ADL episodes ranged from one to five per annum and the majority of the affected (60.4%) experienced a single episode. The average duration of an ADL episode was 8.6 days and in 72.5% of the episodes the affected individuals were incapacitated and unable to do their normal activities for an average duration of 3.7 days. The physical incapacitation associated with ADL episodes emphasizes the significance of lymphatic filariasis as a major public health problem of substantial socio-economic consequences.

Development of rapid assessment procedures for the delimitation of lymphatic filariasis-endemic areas

Lymphatic filariasis caused by Wuchereria bancrofti is a major public health problem in 73 tropical and subtropical countries including India. Delimitation of endemic areas is essential to plan control operations. The current method of night blood survey (NBS) for delimitation is cumbersome, time-consuming and expensive. Therefore, there is a need to develop assessment procedures which can rapidly delimit endemic areas. For this purpose we evaluated three procedures: direct interviewing of key informants using structured questionnaires, an indirect method of a self-administered questionnaires to key informants and physical examination by health workers for the presence of chronic filarial disease. Thirty rural communities in a filariasis-endemic region in Cuddalore district in Tamil Nadu State in southern India constituted the study population. The determination of filariasis endemicity in the village communities assessed by the above procedures was compared in terms of rapidity, specificity, sensitivity and cost with the microfilaria rate and disease rate obtained by night blood sample survey and clinical examination by physicians. Prevalence score, control preference score and weighted mean number of cases with filarial disease per village were calculated using the key informant questionnaire techniques. While the prevalence and control preference score showed low sensitivity and moderate specificity, weighted mean number of cases showed high sensitivity and moderate specificity in identifying endemic villages. The prevalence of disease as determined by the physical examination of a sample population by health workers was highly sensitive in identifying communities endemic for filariasis. The degree of association between the disease rates estimated by physician and trained health workers was significant (r = 0.56; P < 0.05). These observations suggest that the weighted mean number of cases per village obtained through key informant techniques may be considered at a primary level to crudely identify endemic areas, followed by physical examination by health workers for filariasis, since it is relatively cheap and rapid.

Bacteriological studies of blood, tissue fluid, lymph and lymph nodes in patients with acute dermatolymphangioadenitis (DLA) in course of 'filarial' lymphedema

Filarial lymphedema is complicated by frequent episodes of dermatolymphangioadenitis (DLA). Severe systemic symptoms during attacks of DLA resemble those of septicemia. The question we asked was whether bacterial isolates can be found in the peripheral blood of patients during the episodes of DLA. Out of 100 patients referred to us with 'filarial' lymphedema 14 displayed acute and five subacute symptoms of DLA. All were on admission blood microfilariae negative but had a positive test in the past. Blood bacterial isolates were found in nine cases, four acute (21%) and five subacute (26%). In 10 acute cases blood cultures were found negative. Six blood isolates belonged to Bacilli, four to Cocci and one was Sarcina. To identify the sites of origin of bacterial dissemination, swabs taken from the calf skin biopsy wounds and tissue fluid, lymph and lymph node specimens were cultured. Swabs from the calf skin biopsy wound contained isolates in nine (47%) cases. They were Bacilli in nine, Cocci in three, Acinetobacter and Erwinia in two cases. Tissue fluid was collected from 10 patients and contained Bacilli in four (40%) and Staphylococci in three (30%). Lymph was drained in four patients and contained isolates in all samples (100%). They were Staphylococcus epidermis, xylosus and aureus, Acinetobacter, Bacillus subtilis and Sarcina. Three lymph nodes were biopsied and contained Staphylococcus chromogenes, xylosus, Enterococcus and Bacillus cereus. In six cases the same phenotypically defined species of bacteria were found in blood and limb tissues or fluids. In the 'control' group of patients with lymphedema without acute or subacute changes all blood cultures were negative. Interestingly, swabs from biopsy wound of these patients contained isolates in 80%, tissue fluid in 68%, lymph in 70% and lymph nodes in 58% of cases. In healthy controls, tissue fluid did not contain bacteria, and lymph isolates were found only in 12% of cases. This study demonstrates that patients with acute episodes of DLA reveal bacteremia in a high percentage of cases. Diversity of blood and tissue bacterial isolates in these patients points to a breakdown of the skin immune barrier in lymphedema and subsequently indiscriminate bacterial colonization of deep tissues and spread to an blood circulation.

Screening of army soldiers for Wuchereria bancrofti infection in the metropolitan Recife region, Brazil: implications for epidemiological surveillance

Between 1989 and 1995, blood surveys were performed for Wuchereria bancrofti infection in several barracks of the Brazilian army in the metropolitan Recife region. For initial screening, 60 microliters of capillary blood were examined for microfilaria. All men who tested positive had microfilaria quantified by filtration of venous blood through a polycarbonate membrane. Of 23,773 men screened, 585 (2.5%) had microfilaria (mf). Microfilarial density ranged from < 1-8706 mf/ml of blood. Thirteen individuals had ultra-low microfilarial densities (1 mf/11 ml of blood). Characterization of 174 autochthonous cases made it possible to map 8 new districts in 4 cities within metropolitan Recife region where transmission of W. bancrofti was previously unknown. Routine screening of soldiers in the military may provide important surveillance data for national programmes to eliminate transmission of W. bancrofti.

The relationship between infection and disease in Wuchereria bancrofti infection in Ghana

The relationship between infection and clinical disease in Wuchereria bancrofti infection was investigated in a community-based study in different endemic areas in Ghana. At the individual level, there was no association between acute adenolymphangitis and infection (microfilaraemia) status. There was a negative association between infection status and lymphoedema/elephantiasis, but a positive association with hydrocele; however, the intensity of infection was negatively associated with both elephantiasis and hydrocele. The community prevalence of infection was strongly associated with the prevalence of clinical filariasis (especially hydrocele). There was a strong positive association between the prevalence of infection in males and the odds of a case of hydrocele being microfilaraemic, suggesting that there is no acquired immunity to reinfection in cases of hydrocele. The pathophysiologies of elephantiasis and hydrocele may therefore differ from one another, and require further investigation.

Epidemiology of acute filarial episodes caused by Wuchereria bancrofti infection in two rural villages in Tamil, Nadu, south India

This year-long study investigated the epidemiology of acute filarial episodes due to Wuchereria bancrofti in 2 rural villages in south India. The annual incidence of 96.5 episodes/1000 population was significantly higher in males (108.5) than females (84.1) an strongly age dependent. First occurrence of acute disease was observed in 0.86% of the population, and the average duration of each episode was 3.6 +/- 2.0 d. Although more than half (63.5%) of the affected individuals suffered only 1 episode, a few experienced as many as 8 over the one-year period. Individuals with chronic disease were more prone to acute attacks, with 82.9% of the total episodes occurring in this group. No seasonal pattern was observed in the frequency of episodes. Probit analysis showed that the number of episodes per affected person was dependent on sex and chronic condition. Swelling of lymph nodes in the inguinal region and fever were the most common symptoms of acute disease. The high incidence and resulting debility observed in this study suggest that acute episodes are a significant health problem associated with lymphatic filariasis. There is clearly a need for more studies on this acute form of filarial disease to aid the understanding of the aetiology and epidemiology of acute episodes, in planning appropriate control interventions, and in evaluating the resulting health burden.

Re-assessing the global prevalence and distribution of lymphatic filariasis

This paper estimates the global burden of lymphatic filariasis based on a review of the published literature on infection and disease surveys. A method for aggregating and projecting prevalence data from individual studies to national, regional and global levels, which also facilitates the estimation of gender and age-specific burdens, is presented. The method weights in favour of the larger, and hence presumbably more reliable, studies and relies on estimated empirical relationships between gender, age, infection and disease in order to correct studies with incomplete data. The results presented here suggest that although the overall prevalence of filariasis cases is 2.0% globally (approximately totalling 119 million cases), the disease continues to be of considerable local importance, particularly in India and Sub-Saharan Africa. Estimates by age and gender clearly show that, unlike other helminth infections, filariasis is mainly a disease of the adult and older age-classes and appears to be more prevalent in males. This work suggests that the derivation of more accurate estimates of the burden of filariasis will require a better understanding of both the epidemiology and the spatial aspects of infection and disease. It also suggests that filariasis is preventable based on a geographically targeted strategy for control.

Natural history, trend of prevalence and spectrum of manifestations of Bancroftian filarial disease in Pondicherry (South India)

The study examines the changes in the disease parameters of lymphatic filariasis over a period of time based on three surveys during 1957, 1986 and 1992 in Pondicherry, South India. The overall prevalence of filarial disease in the three surveys was 4.7, 6.7 and 9.9% respectively. It was significantly higher in males (1957:5.3%; 1986:13.7%; 1992:18.8%) when compared to females (1957:3.8%; 1986:2.3%; 1992:2.7%) in all the three surveys (P <0.05). The overall prevalence of acute adenolymphangitis declined from 1.0 in 1957 to 0.2 in 1986 and 0.04% in 1992. While the prevalence of hydrocele showed an increasing trend from 2.7 in 1957 to 11.9 in 1986 and 17.3% in 1992, the prevalence of lymphoedema (1.9 in 1957; 1.9 in 1986 and 1.8% in 1992) was stable over the same period. The prevalence of disease was relatively higher in all age groups of both male and female population in 1992 when compared either to 1957 or 1986. Similarly a monotonic increase in the prevalence of hydrocele was observed in all age groups in 1992 when compared to previous surveys. The implications of the changes in prevalence of the chronic manifestations when compared to the changes in the acute manifestations over a period of 35 years are discussed.