Filariasis linfática / Lymphatic filariasis

Las filariasis linfáticas son un grupo de enfermedades causadas por nematodos de la familia Filaroidea que precisan de vectores para su transmisión. El número de infectados se estima en 120 millones a nivel mundial, encontrándose dos tercios de los afectados en Asia. Las manifestaciones clínicas de la enfermedad son variadas (astenia, fiebre, linfedema, etc.) y van a depender de la presencia de gusanos adultos en los vasos linfáticos, la respuesta inmune del huésped y su respuesta endosimbiótica de la bacteria Wolbachia. La confirmación diagnóstica se realiza mediante la detección y visualización de las microfilarias en la sangre o en la piel. El tratamiento farmacológico se basa principalmente en el uso de dietilcarbamazepina. En las especies donde se ha demostrado la presencia de la bacteria endosimbiótica Wolbachia también se recomienda doxiciclina

Lymphatic filariasis is a group of diseases caused by nematodes of the family Filarioidea which require vectors for their transmission. The number of people infected globally is estimated at 120 million, two thirds of which are in Asia. The clinical manifestations of this disease are varied (asthenia, fever, lymphedema, etc.) and will depend on the presence of adult worms in lymph vessels, on the immune response of the host, and on the endosymbiotic response to Wolbachia bacteria. Diagnosis is confirmed by detection and visualization of microfilariae in blood or skin. Drug treatment is mainly based on the use of diethylcarbamazine. Doxycycline is also recommended in species in which the presence of Wolbachia endosymbiotic bacteria has been proven

Lymphatic filariasis and onchocerciasis.

Lymphatic filariasis and onchocerciasis are parasitic helminth diseases that constitute a serious public health issue in tropical regions. The filarial nematodes that cause these diseases are transmitted by blood-feeding insects and produce chronic and long-term infection through suppression of host immunity. Disease pathogenesis is linked to host inflammation invoked by the death of the parasite, causing hydrocoele, lymphoedema, and elephantiasis in lymphatic filariasis, and skin disease and blindness in onchocerciasis. Most filarial species that infect people co-exist in mutualistic symbiosis with Wolbachia bacteria, which are essential for growth, development, and survival of their nematode hosts. These endosymbionts contribute to inflammatory disease pathogenesis and are a target for doxycycline therapy, which delivers macrofilaricidal activity, improves pathological outcomes, and is effective as monotherapy. Drugs to treat filariasis include diethylcarbamazine, ivermectin, and albendazole, which are used mostly in combination to reduce microfilariae in blood (lymphatic filariasis) and skin (onchocerciasis). Global programmes for control and elimination have been developed to provide sustained delivery of drugs to affected communities to interrupt transmission of disease and ultimately eliminate this burden on public health.

A randomized clinical trial to compare the efficacy of three treatment regimens along with footcare in the morbidity management of filarial lymphoedema.

The progression of lymphoedema to elephantiasis associated with increased incidence of episodic adeno-lymphangitis (ADL) is of great concern, as it causes physical suffering, permanent disability and economic loss to lymphatic filariasis patients. This randomized clinical trial aimed to assess the efficacy in terms of reduction of oedema and ADL frequency of three treatment regimens among lymphoedema patients from Orissa, India. The regimens were: (I) oral penicillin--one tablet of 800 000 U penicillin G potassium twice daily for 12 days--repeated every 3 months for 1 year; (II) diethylcarbamazine--6 mg/kg bodyweight for 12 days-repeated every 3 months for 1 year; and (III) topical antiseptic, i.e. betadine ointment. Foot care was part of all regimens. All three drug regimens are efficacious in reducing oedema and frequency of ADL episodes. Although the efficacy was slightly higher in regimen I, the difference was not significant. About half of all patients had reduced oedema after the 90 days of treatment, with oedema reduction of 75-100% in 20%. A major proportion of the remaining patients had oedema reduced by less than 25%. The proportion of people whose oedema reduced was slightly but not significantly lower in regimen II. anova revealed that lymphoedema reduction varied according to grade; being greatest at grade 1 lymphoedema, followed by grade 2. All three regimens significantly reduced ADL frequency after 1 year of treatment. This may be because of foot care as well as use of antibiotics. The estimated costs of treatment per patient for a period of 3 months are US$2.4, 1.5 and 4.0 respectively for regimen I, II and III. Thus affordable treatments with simple antibiotics and foot care can give substantial relief to the patients and reverse early lymphoedema.

Treatment costs and work time loss due to episodic adenolymphangitis in lymphatic filariasis patients in rural communities of Orissa, India.

OBJECTIVE: To determine the economic loss in terms of treatment costs and loss of productive time because of acute episodes of adenolymphangitis (ADL) caused by lymphatic filariasis (LF) in a rural population of coastal Orissa, India. METHODS: Data on expenditure on treatment and loss of work along with other epidemiological information were collected through a 1-year surveillance of 113 acute episodes of ADL from 72 individuals of the study population (5.42%). The activity patterns of patients for 24 h of one episode were documented, and data on age- and sex-matched controls were also collected. Standardized Z-test, paired t-test, logistic and multiple regressions were used. RESULTS: Those patients who did incur expenses spent Indian Rupees 92 on average (approximately US$ 1.85) on each episode. The ADL episodes curtailed the productive activity of patients. Patients (88%) were unable to attend to any economic activity compared with 47% of controls who had no history of disease. Similarly during 55% of episodes, females (vs. 8% of controls) could not attend to any domestic work. The mean number of hours spent on economic or domestic activities was significantly lower among patients. Disease status and sex had significant influence on total absenteeism from gainful employment; and similarly, age, family type and disease status influenced total domestic work hours among women. CONCLUSIONS: The results demonstrate the extent of the economic burden caused by acute LF and provide justification for strengthening the ongoing LF elimination programme.

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 in the Caribbean region: the opportunity for its elimination and certification.

In order to support the case for a certification of elimination of lymphatic filariasis (LF) in some Caribbean countries, we compared the prevalence of circulating Wuchereria bancrofti antigen in communities in Guyana, Suriname, and Trinidad. For the study, we assayed school children in six communities in Guyana, five communities in Suriname, and three communities in Trinidad for the prevalence of circulating W. bancrofti antigen, using a new immunochromatographic test for LF. We also assayed adults in these three countries, with a special focus on Blanchisseuse, Trinidad, where mass treatment for LF elimination had been carried out in 1981. The prevalences of W. bancrofti circulating antigen found in the school children populations ranged from 1.7% to 33.2% in Guyana and were 0.22% overall in Suriname and 0.0% in Trinidad. Among adults in two Guyana communities the prevalences were 16.7% and 32.1%. The results were all negative from 211 adults in communities in the north, center, and south of Trinidad, as well as from 29 adults in Suriname. The data suggest that contrary to reports of LF endemicity from the World Health Organization, LF may no longer be present in Trinidad and may be of very low prevalence in Suriname. Trinidad and Tobago and other Caribbean nations proven negative could seek to be awarded a certificate of LF elimination. In Suriname the small localized pocket of infected persons who may serve as a reservoir of LF infection could be tested and appropriately treated to achieve LF elimination. Such LF-positive countries as Guyana should access new international resources being made available for LF elimination efforts. An adequate certification program would help identify which countries should seek the new LF elimination resources.

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.

[Studies on the recurrent attacks of acute adenolymphangitis due to Malayan filariasis].

OBJECTIVE: To explore the role of filarial and bacterial infections in the recurrent attacks of acute adenolymphangitis due to malayan fialriasis. METHODS: 1. To observe the seasonal fluctuation of acute attacks by performing monthly follow-up on patients with history of acute attacks in recent years. 2. To study the relationship between bacterial infection and filarial adenolymphangitis by performing bacteria culture and anti-streptolysin O test. 3. To investigate the variation of acute attacks by controlling filariasis transmission or by treating patients with a history of recurrent acute attacks. RESULTS: 1. The peak of acute attacks in patients coincided with the peak of vector transmission season. 2. Of the 97 cases examined by bacteria culture, 90 cases were negative; of the 255 cases examined by anti-streptolysin O test, the titres in 94.1% (143/152) of the cases with first attack and simple adenolymphangitis were within normal limits, however, the titres in 27.2% (28/103) of the cases complicated with elephantiasis were increased. 3. The acute attack rate of adenolymphangitis per year reduced significantly in cases with first attack and simple adenolymphangitis after effective control of filariasis transmission. 4. There was no evidence of the reduction of acute attacks by treating patients with DEC alone. CONCLUSION: In malayan filariasis endemic areas, the main causes of recurrent attacks of acute adenolymphangitis might be the repeated filarial infections due to the persistence of filariasis transmission.

Acute attacks in the extremities of persons living in an area endemic for bancroftian filariasis: differentiation of two syndromes.

The natural history of lymphatic disease in human filariasis remains unclear, but recurrent episodes of acute lymphangitis are believed to constitute a major risk factor for the development of chronic lymphoedema and elephantiasis. Prospective analysis of 600 patients referred to the filariasis clinic of the Centro de Pesquisas Aggeu Magalhães/FIOCRUZ in Recife, Brazil, indicated that 2 distinct acute syndromes accompanied by lymphangitis occur in residents of this filariasis-endemic area. One syndrome, which we call acute filarial lymphangitis (AFL), is caused by the death of adult worms. It is relatively uncommon in untreated persons, usually is asymptomatic or has a mild clinical course, and rarely causes residual lymphoedema. The second syndrome, of acute dermatolymphangioadenitis (ADLA), is not caused by filarial worms per se, but probably results from secondary bacterial infections. ADLA is a common cause of chronic lymphoedema and elephantiasis in Recife as well as in other areas of Brazil where lymphatic filariasis is not present. The syndromes of AFL and ADLA can be readily distinguished from each other by simple clinical criteria.

The epidemiology of acute adenolymphangitis due to lymphatic filariasis in northern Ghana.

A study to investigate the socioeconomic impact of lymphatic filariasis was conducted in a rural community in northern Ghana. The incidence, severity, and duration of acute adenolymphangitis (ADL), as identified by local terminologies and confirmed using World Health Organization diagnostic criteria, were investigated. Local terminologies were found to be highly specific and sensitive for diagnosing ADL (sensitivity = 0.978, specificity = 0.980). The incidence of ADL was 95.9 per 1,000 per annum among adults more than 10 years of age, being much higher in females than in males. Among those with elephantiasis and other chronic filarial symptoms, there was no clear relationship between the stage of chronic lymphedema and the incidence of ADL. The incidence of ADL was found to be closely related to the rainfall pattern. The design of the study, its findings, and the public health implications of the findings are discussed in this paper.

A preliminary study of filariasis related acute adenolymphangitis with special reference to precipitating factors and treatment modalities.

Episodic adenolymphangitis (ADL) is one of the important clinical manifestations of lymphatic filariasis. Recurrent ADLs contribute to the progress of the disease and also have important socioeconomic implications since they cause significant loss of man days. The present study was conducted in order to identify the precipitating factors responsible for ADL attacks and also to examine the different modalities of treatment. Sixty-five individuals with filariasis related ADL attacks, who are residents of Alleppey district (endemic for Brugia malayi) were studied. All efforts were taken to identify the precipitating factors for ADLs in these individuals. They were hospitalized for a period of five days or more. All of them received symptomatic antipyretic/antiinflammatory therapy and topical antibiotic/antifungal treatment of the affected limbs. They were then randomly allocated to one of the following four regimens: group I - symptomatic alone; group II - symptomatic plus antibiotics; group III - symptomatic followed by diethylcarbamazine citrate (DEC) and group IV - symptomatic plus antibiotic followed by DEC. Patients in groups III and IV received DEC every three months up to one year. There was a significant relationship between the number of ADL attacks and the grade of edema. Presence of focus of infection in the affected limb could be identified in 28 of the 65 patients. In the majority of patients (48) response to treatment was rapid (resolution in less than five days). Neither antibiotics nor DEC (given at intervals of three months) appeared to alter the frequency of ADL attacks. On the otherhand simple hygienic measures combined with good foot care and local antibiotic/antifungal cream application (where required), were effective in reducing the number of ADL attacks.

[Experimental infection of periodic Brugia malayi in man].

We described the results of ten-year observations on the clinical manifestations, pathology, immunity to filariasis and aetiological biology of filariae in three volunteers (first author and his family members) who were inoculated experimentally with infective larvae of periodic Brugia malayi in 1981 and without use of any antifilariasis drugs. Microfilariae were first detected at 41 and 46 weeks after inoculation in two subjects and remained detectable in a small number until 8 and 8.5 years after infection. Eosinophilia occurred mainly before and at the initial stage of microfilaremia. The increase in the lymphocytes to some extent was observed at 2-156 weeks after infection. Biopsy at inoculation site 6 weeks after inoculation showed the lymph node with the infiltration of inflammatory cells, mainly eosinocytes, lymphocytes and monocytes. Lymphangiotasis and lymphostasis were observed in both limbs and pelvic regions by lymphangiogram taken 11 weeks after inoculation. Antibody against B. malayi first appeared at 2-5 weeks after infection and reached the highest at 12-56 weeks and thereafter declined gradually. Two subjects turned to be antibody free 10 years after infection. E-rosette forming lymphocytes became lower than normal at 11 weeks and recovered to normal within 10 years after infection.

Bancroftian lymphangitis in northeastern Brazil: a histopathological study of 17 cases.

The histological features in 17 patients (3 males and 14 females) with bancroftian lymphangitis, apparently not associated with lymphadenitis, are described. Degenerative alteration in the worms and a severe inflammatory process were observed in the great majority of the cases. The patterns of tissue reaction varied, including exudative, infiltrative and granulomatous lesions. Eosinophils were present, usually in great numbers. Thirteen out of 14 female subjects showed involvement of the breast lymphatics, and in two of these cases microfilariae were found in addition to adult worms. The breast parenchyma was in general spared. In men, lymphatics of the epididymis were affected; in one case, the patient was submitted for surgical castration for prostatic cancer and intact filarial worms without tissue reaction were incidentally detected in peritesticular lymphatics.