Enhanced efficacy of sequential administration of Albendazole for the clearance of Wuchereria bancrofti infection: Double blind RCT

Till today, there is no effective treatment protocol for the complete clearance of Wuchereria bancrofti (W.b) infection that causes secondary lymphoedema. In a double blind randomized control trial (RCT), 146 asymptomatic W. b infected individuals were randomly assigned to one of the four regimens for 12 days, DEC 300 mg + Doxycycline 100 mg coadministration or DEC 300 mg + Albendazole 400 mg co-administration or DEC 300 mg + Albendazole 400 mg sequential administration or control regimen DEC 300 mg and were followed up at 13, 26 and 52 weeks post-treatment for the clearance of infection. At intake, there was no significant variation in mf counts (F(3,137)=0.044; P=0.988) and antigen levels (F(3,137)=1.433; P=0.236) between the regimens. Primary outcome analysis showed that DEC + Albendazole sequential administration has an enhanced efficacy over DEC + Albendazole co-administration (80.6 Vs 64.7%), and this regimen is significantly different when compared to DEC + doxycycline co-administration and control (P<0.05), in clearing microfilaria in 13 weeks. Secondary outcome analysis showed that, all the trial regimens were comparable to control regimen in clearing antigen (F(3, 109)=0.405; P=0.750). Therefore, DEC + Albendazole sequential administration appears to be a better option for rapid clearance of W. b microfilariae in 13 weeks time. (Clinical trials.gov identifier – NCT02005653)

Effect of a single dose of diethylcarbamazine, albendazole or both on the clearance of Wuchereria bancrofti microfilariae and antigenaemia among microfilaria carriers: A randomized trial.

Background. Lymphatic filariasis is a major vector-borne parasitic disease. The global programme to eliminate lymphatic filariasis was launched in 1997 and currently over 570 million people are covered under it in 48 countries. Mass annual single-dose drug administration of diethylcarbamazine (DEC), co-administrated with albendazole for 5–6 years and mass distribution of diethylcarbamazine-fortified salt are the two strategies for elimination of filariasis. Methods. Asymptomatic volunteers residing in Puducherry, India were screened for microfilaria (mf) by examining nocturnal thick blood smears. Those testing positive were randomly assigned to receive a single dose of DEC (6 mg/kg body weight) or albendazole 400 mg or both. Participants were hospitalized for 5 days. Membrane filtration count was used to assess microfilaraemia and ELISA (Og4C3) assay to measure circulating filarial antigens (CFA). Measurements were done before treatment and at 1, 2 and 3 years post-treatment. Viability of the adult worms was assessed by looking for the filarial dance sign (FDS) using ultrasound examination of the scrotum in men with hydrocele. Results. Fifty-four microfilaraemic individuals were studied. The mf prevalence started decreasing only by day 180 posttreatment in the DEC group but much earlier in the other two groups (day 30 in the albendazole and day 90 in the DEC with albendazole group). The decrease in mf was marginal (17.6%, 26.3% and 27.8%, respectively) by the end of year 1 posttreatment, but significant (96.7%, 78.6% and 93.3%, respectively) by the end of year 2 post-treatment (p<0.05). By the end of year 3, the level decreased to 80% in the DEC, 90% in the albendazole and to 100% in the DEC and albendazole groups. However, the mf intensity decreased © The National Medical Journal of India 2010 Vector Control Research Centre, Department of Health Research (ICMR), Indira Nagar, Puducherry 605006, India S. L. HOTI, S. P. PANI, P. VANAMAIL, K. ATHISAYA MARY, L. K. DAS, P. K. DAS Correspondence to S. L. HOTI; slhoti@yahoo.com significantly (by 39%; p<0.05) by day 7 post-treatment in both the DEC and DEC with albendazole groups, but only by day 30 in the albendazole group. In all the drug groups, the prevalence as well as intensity of CFA returned to pretreatment levels by the end of year 3 post-treatment. Conclusion. Annual single-dose administration of all the 3 drug regimens significantly reduced antigenaemia levels. There were no significant differences in the efficacy and overall pattern of CFA clearance between the 3 drug regimens.

Predominant Learning styles adopted by AIMST University students in Malaysia.

Introduction: An assortment of learning styles is adopted by medical students. Some like to learn by seeing, some by hearing and some by demonstration. Understanding their preferred learning styles as visual, auditory, read-write or kinesthetic learners will help improve the teaching methods adopted. Objective and Goal: role of the educator necessitates making the most of each teaching opportunity by understanding the characteristics of the learning audience and incorporating demonstrated principles of adult educational design, with a focus on collaborative learning and variety in presentation techniques. The goal is to provide student oriented education, producing efficient doctors. Design and participants: A cross-sectional study among 214 medical students of the AIMST University, conducted in 2008. Main outcome measures were: 1. Learning style {visual (V), auditory (A), readwrite( R), kinesthetic (K)} 2. Preferred study practice (alone, in pairs or in groups). Results and Discussion: Preference for different learning styles were, visual (V) 9%, auditory (A) 28%, reading/writing (R) 38% and kinesthetic (K) 35%. 51.4 % of the total 214 students preferred a single mode of information presentation (either V, A, R, or K). Of the 104 students (48.6 % of the total 214 ) who preferred multiple modes of information presentation, some preferred two modes (bimodal, 25%), some preferred three modes (tri-modal, 12%), and some preferred four modes (quadri-modal, 67%). Practical implications: With growing interest in learning styles, an awareness of students’ preferences will be of particular value in designing course delivery strategies which combine an appropriate mix of lectures, Problem based learning (PBL) sessions and practical hours. Originality/value: Multiplicity exists in the learning styles of students and the accomplishment of teaching goals is based on the ability to understand the complexity and to use the knowledge of these differences to balance these disparities among the students in a class.

The plight of chronic filarial lymphoedema patients in choice of health care and health care providers in Pondicherry, India.

Lymphatic filariasis has a wide spectrum of clinical manifestations with asymptomatic parasite carriers at one end and irreversible lymphoedema of extremities at the other. Irreversible lymphoedema of extremities is one of the disabling conditions that drive the affected patients to seek treatment from various systems of medicines and health care providers. This study attempts to map the care seeking pattern and behaviour of patients with chronic filarial lymphoedema of lower limbs in an urban area. Consecutive filarial lymphoedema patients from the VCRC filariasis clinic were recruited for the study. A pre-tested semi-structured questionnaire was used for interrogation of the patients. A total of 56 lymphoedema patients participated in the study. Majority (94.6%) of the patients sought medical management only. There was no difference (P>0.05) between the proportion of patients attending government (37.5%) and private (44.3%) medical care facilities There was also no difference in the proportion of patients' first consultations in private or government health care facilities. About 57.1% patients approaching governmental institutions opted for primary/secondary health care system. No particular sequential pattern of seeking health care was observed and the 56 study subjects followed 40 treatment-seeking routes by switching from one care provider to the other. The causes of not coming to the clinic for further check-up were 'no acute attacks' (30.4%), 'reduction in oedema volume' (21.7%), 'advised treatment being taken at home' (26.1%) and 'loss of daily wages' (21.7%). The study highlights the need to involve the private medical sector in morbidity management of filarial lymphoedema and to make governmental health facilities more accessible and user-friendly.

Locomotor disability in bancroftian filarial lymphoedema patients.

Disability prevention in cases with lymphatic filarial disease has been a research priority in view of the current programme on global elimination of lymphatic filariasis. This is also important for estimation of disease burden, impact evaluation, developing strategy for morbidity management and rehabilitation for lymphoedema patients in the endemic countries. In this communication, we are presenting the results of quantification of functional limitations of lower extremities with lymphoedema caused due to bancroftian filariasis by objective assessment of movement of joints and power of muscles in the affected legs. A total of 81 consecutive lymphoedema patients attending a filariasis clinic in Pondicherry urban locality were recruited for the study. Assessment for restriction of movement of joints and loss of power of muscles was carried out as in Manual for doctors to evaluate permanent physical impairment, prescribed by an expert group of WHO and Ministry of Health, Govt. of India on evaluation for permanent disability. Of the cases assessed, 40% in grade-I, 55% in grade-II, 77.3% in grade-III and 94.7% in grade-IV lymphoedema cases had functional limitations either in joint movements or power of muscles or both. The effective loss of locomotor/function (combined loss of joint movement and power of muscles in %) increased with stage of lymphoedema (grade-I-4.3+7.4, grade-II-7.0+8.4, grade-III-15.4+14.8 and grade IV- 33.2+22.8). The degree of loss varied significantly between the grades (P< 0.0001). The methodology used in this study can be adapted to evaluate the impact of the morbidity management component of strategy for Elimination of Lymphatic Flariasis (ELF) programme. This study will also enable researchers for fine-tuning the method for estimating disease burden and, to develop and evaluate strategies for morbidity management/rehabilitation of filarial lymphoedema patients.

Kinetics of microfilaraemia & antigenaemia status by Og(4)C(3) ELISA in bancroftian filariasis.

BACKGROUND & OBJECTIVE: Bancroftian filariasis caused by Wuchereria bancrofti is endemic in many parts of India. In recent years diagnosis of W. bancrofti infection has been revolutionized with the availability of filarial antigen tests, which is important in monitoring success of chemotherapy. We carried out this study to measure microfilariaemia and antigenemia levels in bancroftian microfilariae (mf) carriers at 1 yr follow up after chemotherapy, in lymphoedema patients and in endemic controls from a filariasis endemic area in Tamil Nadu State using Og(4)C(3) ELISA to identify the best marker to assess success of chemotherapy. METHODS: Serum samples were collected from 30 bancroftian microfilaremic (Mf) carriers pre-treatment and at sequential intervals (7,30,60,90,180 and 365 days) following treatment with diethylcarbamazine (DEC:6mg/kg body weight, single dose), 30 lymphoedema patients (without treatment) at periodic intervals, and 68 control subjects (24 endemic normal subjects in filariasis endemic area in Tamil Nadu State, 24 non-endemic normal subjects residing in Chandigarh, India; 5 brugian filariasis, 5 endemic control subject in brugian filariasis endemic area and 10 other disease controls). The circulating antigen of W. bancrofti was measured quantitatively using Og(4)C(3) ELISA kit. RESULTS: In Mf carriers, there was no significant difference in microfilariae count in pre- and post-treatment (PT) samples till day 30 while significant differences were observed in pre- and sequentially collected post-treatment (PT) samples day 60 to 180 (P<0.001), day 365 (P<0.005). However, there was no significant difference in antigenaemia levels between pre-treatment (day 0) and PT samples collected on day 7 onwards till day 365. Though of the 19 patients who could be followed up till 365 days PT, 4 (21%) were amicrofilaraemic, none became antigen negative. No significant difference was found in antigenaemia levels in sequentially collected samples from lymphoedema patients. Significant differences were observed in antigenaemia levels in samples collected at the start of study in mf carriers as compared to lymphoedema patients and endemic normal subjects (P<0.001). Subjects (non-endemic control) residing in filariasis free area (24), brugian endemic area (5), B.malayi infected patients (5) and patients with other parasitic diseases (10) were found antigen negative. INTERPRETATION & CONCLUSION: Annual single dose of DEC therapy alone may not result in complete clearance of infection and detection of antigenaemia rather than microfilaraemia may be taken into consideration as an indicator of successful chemotherapy. The study supports the earlier view that filarial antigenaemia is relatively common in amicrofilaraemic and asymptomatic subjects in endemic areas and further studies are needed to determine the clinical significance, prognosis and effective management of such infections in endemic areas.

Tolerability and efficacy of a three-age class dosage schedule of Diethylcarbamazine citrate (DEC) in the treatment of microfilaria carriers of Wuchereria bancrofti and its implications in mass drug administration (MDA) strategy for elimination of lymphatic filariasis (LF).

A six-age class dosage schedule of Diethylcarbamazine (DEC) of 50mg (1-2 years), 100mg (3-4 years), 150mg (5-8 years), 200mg (9-11 years), 250mg (12-14 years) and 300mg for above 14 years is being adopted for annual single dose MDA for LF elimination treat Wuchereria bancrofti microfilaria carriers. In order to increase the community compliance as well as to make the distribution easier during MDA, a revised 3 age class dosage schedule of 100mg (2-4 years), 200mg (5-14 years) and 300mg for above 14 years was evaluated for its tolerability and efficacy. By this change, it was observed that the 4-8 years age class is receiving 50 mg higher and 11-14 years age class is receiving 50mg lesser dose compared to the earlier class schedule. Therefore, the safety aspect in the age class of 4-8 years and efficacy component in the age class of 11-14 years were assessed. Apparently "healthy" asymptomatic microfilaraemic volunteers between the age class of 4-8 and 11-14 years were recruited for the study. The incidence of side reaction in the 4-8 years age class was 50.0% with 150mg dose and 66.7% with 200mg (P>0.05). No life threatening adverse reactions was observed in any dosage schedule. Fever, headache and myalgia, the predominant adverse reactions were mild and similar in both schedules. The mean intensity of the three major specific adverse reactions (fever, headache and myalgia) also did not differ significantly (P>0.05). For the purpose of LF elimination, efficacy in terms of reduction in mean microfilaria load is important. In the 11-14 year age class considerable reduction in the geometric mean density (GMD) was observed by day 90 and 180 post-therapy in both groups (250mg group and 200mg group) compared to pre-therapy level. By day 360 post-therapy, the difference was statistically not significant (P>0.05) (reduction of 72.2% in 250mg and 69.6% reduction in 200mg). The reductions in GMD were statistically significant when compared to pre-therapy levels in both the old (250mg) and new (200mg) doses. Thus, three- age class dosage schedule is as safe and efficacious as the six- age class schedule.

Tolerability and efficacy of single dose diethylcarbamazine (DEC) alone or co-administration with Ivermectin in the clearance of Wuchereria bancrofti microfilaraemia in Pondicherry, South India.

The tolerability and efficacy of single dose DEC (12mg/kg body weight) or co-administration of DEC (6mg/kg body weight) with Ivermectin (200 or 400 mcg/kg of body weight) was studied in 60 asymptomatic W. bancrofti microfilariae (Mf) carriers following a double blind randomized design. The drugs were tolerated well. The incidence of adverse reactions of DEC (85.0%), DEC + Ivermectin 200mcg (95.0%) and DEC + Ivermectin 400mcg (100%) did not vary significantly (P>0.05). The mean score of adverse reaction intensity due to DEC + Ivermectin 200mcg (1.41) was significantly higher compared to DEC (0.61) (P<0.05). However, there was no significant difference between and DEC +Ivermectin 400mcg (0.89) and DEC + Ivermectin 200mcg (1.41) and DEC + Ivermectin 400mcg and DEC. The major adverse reactions were fever, headache and myalgia in all groups. The incidence and intensity of the adverse reactions were maximum between 24 to 48 hours of post therapy. The haematological and biochemical parameters did not vary significantly between pre and 7-day post therapy values in any of the study groups (P>0.05). Efficacy was measured in terms of proportion of cases clearing microfilaraemia completely and reduction in geometric mean parasite density in comparison to pre therapy levels. At the end of one year, DEC with Ivermectin 400mcg group showed significantly higher efficacy in complete clearance of Mf (94.4%) than that of DEC with Ivermectin 200mcg (60.0%) or DEC alone (52.6%) (P<0.05). However, no significant difference was observed in reduction of geometric mean Mf density (99.9%, 99.7%, 99.5% respectively). In all the groups, the tolerability and efficacy of the drugs were independent of host age and gender.

Comparison of an immunochromatographic card test with night blood smear examination for detection of Wuchereria bancrofti microfilaria carriers.

BACKGROUND: At present, two diagnostic tests--Og4C3 ELISA and an immunochromatographic card test (ICT)--are available to detect circulating filarial antigens of Wuchereria bancrofti in serum/whole blood samples collected during the day. We aimed to assess the sensitivity of the new format card test 'NOW ICT Filariasis' in detecting microfilaria carriers of W. bancrofti in comparison with conventional microscopic techniques and Og4C3 ELISA. METHODS: A total of 200 persons were selected from two villages following a quota sampling design (100 in each village). The required number of houses was selected using a systematic sampling procedure with a random start of the first household. Blood samples were taken from all the available persons in each selected house until the quota of 100 was reached. The new format ICT test, Og4C3 ELISA and night blood smear examination for microfilaria were carried out following standard procedures. RESULTS: The sensitivity of the new format ICT test was 100% among microfilaria carriers (detected by both early and late readings). The kappa statistic measure of agreement between the two readings of all the samples (n =200) tested was 0.811 (p<0.05). The new format test also reported 25% of microfilaria-negative individuals as being positive for circulating filarial antigens. However, the diagnostic lines were not stable beyond 10 minutes (particularly in the case of amicrofilaraemic persons). Though there was an overall agreement between the results of ICT and Og4C3 tests (kappa =0.612; p< 0.05), the sensitivity of the Og4C3 test was lower than that of ICT. CONCLUSION: The new format ICT test is highly sensitive in detecting microfilaria carriers in endemic communities. Improvement in the format to provide stable diagnostic lines, specificity of the format and cost of the test kit are to be considered before its large-scale use.

The preferential site of adult Wuchereria bancrofti: an ultrasound study of male asymptomatic microfilaria carriers in Pondicherry, India.

BACKGROUND: The traditional method of detection of microfilaria in night blood specimens for the diagnosis of Wuchereria bancrofti infection is being replaced with circulating filarial antigen in day blood specimens, which has a high sensitivity. However, both methods are indirect tests to detect the presence of adult worms in vivo. Localization of adult worms in vivo in their natural habitat may help in understanding better the end-point of drug treatment, the adulticidal action of antifilarial drugs, and in locating the site of lymphatic pathology. We used ultrasound examination to assess the preferential location of adult worms in an area endemic for lymphatic filariasis. METHODS: Ultrasound examination was done in 36 asymptomatic male carriers of Wuchereria bancrofti microfilaria to detect the location of adult worms. Both sides of the scrotum (root of the scrotum, epididymis, spermatic cord, testis and the adjoining area), lymphatic vessels and inguinal, popliteal, axillary and epitrochlear lymph nodes were examined using a 7.5 MHz probe in real-time B mode. RESULTS: The 'filaria dance sign (FDS)' suggesting the presence of adult worms was observed in 22 carriers (61%). The preferential site of location of the adult worms was the intrascrotal juxtatesticular lymphatic vessels in 'nests' along the lymphatic vessels of the epididymis, spermatic cord and paratesticular region. The number of nests varied between 1 and 4 with a mean size of 0.3 cm2. In 95% of cases, localization of the worms was unilateral. The mean microfilaria (SD) count-positive cases for those with the filarial dance sign (264 [199]) was significantly higher (p<0.05) than for the negative cases (171 [196]). CONCLUSION: Ultrasound visualization of adult worms of Wuchereria bancrofti in vivo is possible and confirms the concept that the worms have their own territory and reside in 'nests'. The preferential site of localization of the adult worms in men is the intrascrotal juxtatesticular lymphatic vessels.

Detection of day blood filarial antigens by Og4C3 ELISA test using filter paper samples.

BACKGROUND: The launching of the global filariasis elimination programme has necessitated the use of highly sensitive and specific diagnostic tests. The Og4C3 monoclonal antibody-based ELISA test has been found to be highly specific and sensitive for the diagnosis of filariasis using night blood samples. However, it requires a serum sample which poses problems of transport and storage. Collection of blood samples on filter paper the will greatly circumvent these problems. Therefore, we evaluated the utility of the Og4C3 assay on filter paper samples collected during daytime. METHODS: Blood samples were collected from 63 microfilariae (mf) carriers during different time periods in a day on filter paper discs as well as venous blood for sera. The mf carriers and chronic (hydrocele n = 20; lymphoedema n = 120) and acute filariasis (adenolymphangitis n = 39) patients were from the endemic areas and the non-endemic normals were from Uthagamandalam district of Tamil Nadu, India. The filarial antigens in the samples were determined using the Og4C3 filarial antigen assay as per the manufacturer's instructions (JCU TrapBio, Australia). The sensitivity of the assay on sera and filter paper samples collected during night and also on filter paper samples collected during different time intervals of the day were compared with those of the membrane filtration technique, which was used as a gold standard. RESULTS: The geometric mean titre of the sera samples collected during night was 11 units/ml for non-endemic normals and 601.2 units/ml for mf carriers. The specificity of the assay on sera samples collected during night was 100% and the sensitivity 96.8% and the positive and negative values were 100% and 95.2%, respectively. The antigen positivity of the filter paper samples collected during morning hours was 93.3% while it was 76.6% and 86.7% for afternoon and evening hours. A significant association was observed between antigenaemia levels and mf density in the blood samples collected during the night. CONCLUSION: The samples collected on filter paper during the day can be used as an alternative to sera samples for detection of filarial antigens employing Og4C3 ELISA. Also, samples collected during morning hours yield a higher positivity. The assay when applied to serum samples will be useful especially when quantitative results are required.

Factors influencing response to lymphonodovenous shunt in filarial lymphoedema.

BACKGROUND: Although several studies have been published on lymphonodovenous shunt, there are no objective data either on the outcome of lymphoedema or on various parameters likely to influence the results. METHODS: A trial of lymphonodovenous shunt was carried out in 75 patients with unilateral filarial lymphoedema. The primary aim of the trial was to identify a cohort of responders as against non-responders and to correlate the outcome with various factors such as age, gender, duration and preoperative grade of lymphoedema, number of preoperative attacks of adenolymphangitis, operative impression of the lymph node, effect of venous reflex and type of nodovenous anastomoses. Change in oedema volume was measured objectively by water displacement method using the normal limb as a control. RESULTS: There was no operative mortality. Predominant postoperative complications included wound haematoma (8.5%), wound infection (13.6%) and transient lymphorrhoea (13.6%). In the immediate postoperative period, a reduction of 25%-50% in the oedema volume was recorded in 46.7% of cases and of more than 50% in 17.3% cases. The difference in response with respect to the type of lymphonodovenous shunt was not statistically significant, although the end-to-side type of shunt showed marginally better results. The response was significantly higher in patients with preoperative oedema volume more than 2 L. There was a significant reduction in postoperative attacks of adenolymphangitis, irrespective of the reduction in oedema volume. Of the 75 patients, 22 showed regression of oedema volume to preoperative or higher levels in the postoperative phase. A majority (21/22) could be identified as non-responders within 3 months of surgery. CONCLUSION: The best results of lymphonodovenous shunt were seen in patients with large-volume lymphoedema. The results are better when combined with early excisional surgery. Other factors did not significantly affect the outcome. Non-responders could be identified within 3 months after surgery. Even in patients who did not respond well, a significant decrease in the frequency of adenolymphangitis attacks was observed. Higher initial oedema volume and history of higher frequency (25-50 per year) of adenolymphangitis attacks can be considered as indicators for good response to lymphonodovenous shunt.

Intestinal geohelminthiasis in the developing world.

Intestinal parasitic helminths such as roundworms (Ascaris lumbricoides), hookworms (Ancylostoma doudenale and Necator americanus) and whipworm (Trichuris trichiura) are common in the developing world. Strongyloides stercoralis, though not so common, also contributes to health problems. The prevalence of intestinal worm infestation in India varies from 5% to 76%, which is similar to that in other developing countries. These parasitic infestations are acquired by ingestion, inhalation or penetration of the skin by the infective forms. Ascaris causes many intestinal and respiratory symptoms and plays an important role in precipitating protein-energy malnutrition in undernourished children. Hookworms cause anaemia and hypoproteinaemia. In areas where hookworm infestation is endemic, 90% of pregnant mothers are anaemic. Trichuriasis as a causative agent of human disease has only recently gained attention. Heavy infestation with T. trichiura can result in severe colitis and significant blood loss. This in turn can lead to impaired cognitive functions which are reversible on treatment. Though not as widely prevalent as the other geohelminths in India, Strongyloides stercoralis infestation can be fatal in debilitated and immunosuppressed children. So far, the impact of these parasites on the health of children has been underestimated and concentrated efforts to minimize the worm load and its consequences have not been given due importance in our health policies. This article reviews the pathophysiology, clinical impact and control options of the most commonly prevalent geohelminths in the developing world.

Rapid assessment procedures (RAP) for lymphatic filariasis.

BACKGROUND: New strategies are emerging for control of filariasis in terms of chemotherapy and vector control. Field application of these tools requires mapping and prioritization of filaria-endemic areas and quantification of the infection/ disease burden. Available procedures are time-consuming, costly and have poor sensitivity. Therefore, rapid assessment procedures need to be developed to assess the disease burden as well as monitor and evaluate control programmes. METHODS: Data collected on different variables from 25 areas in India and elsewhere were used. The relationship between prevalence of human infection and vector infection rate was analysed quantitatively. Due to lack of independent samples, only qualitative analysis was carried out between other epidemiological variables such as infection and disease prevalence in relation to age, gender and manifestation. RESULTS: There was a significant positive correlation between vector infection rate and infection prevalence in humans, suggesting that vector infection can be used as an indicator in the rapid assessment of infection prevalence. Scatter plots showed that community screening may be limited to the age group of 11-30 years for infection prevalence and 20-50 years for disease prevalence. Further, clinical surveys may be limited to only hydrocele prevalence which may be sufficient to predict the total disease. This can also be used as an alternative method by the community itself for delimiting endemic areas. CONCLUSIONS: Vector infection rate may be used as an indicator for rapid assessment of human infection. Alternatively, blood smear examination could be limited to the age group of 11-30 years. For a rapid survey of the diseases, males in the age group of 20-50 years could be examined only for hydrocele.

Tropical vaginal hydroceles: are they all filarial in origin?

Hydrocele of the tunica vaginalis testis has been conventionally used as an absolute indicator of filarial disease in most clinical surveys. The prevalence of filarial etiology in 100 consecutive hydroceles was studied using clinical, parasitological, histopathological and immunological parameters. Filarial etiology could be proved in 57% of hydrocele cases using major criteria: presence of microfilaria in hydrocele fluid, presence of chyle in hydrocele fluid, demonstration of adult worm in tunica, ratio of fluid antibody titer to serum antibody titer more than 2 and presence of filarial antigen in hydrocele fluid. The results of other tests in these 57 cases were used to define the minor criteria. In the other 43 cases, based on the minor criteria, 12 hydroceles could be classified as likely to be due to filariasis and the rest were probably non-filarial. Thus only 69% of hydroceles were definitely or probably filarial.

Clinical manifestations of bancroftian filariasis with special reference to lymphoedema grading.

We report on some aspects of progression of chronic disease and its association with acute manifestations with special reference to grades of lymphoedema in bancroftian filariasis. These analyses were based on the clinical history and clinical findings of 1300 individuals at the time of their first visit to the filariasis clinic at a centre in south India. The mean number of adenolymphangitis (ADL) attacks in one year was 4.9 +/- 1.7, 5.5 +/- 0.9 and 10.4 +/- 3.2 in patients with grade I, grade II and grade III lymphoedema respectively. The mean duration of oedema was 47.4 +/- 5.9 days, 6.2 +/- 0.5 and 8.6 +/- 0.9 yr in patients with grade I, grade II and grade III lymphoedema respectively. These findings suggest that the progression of lymphoedema from one grade to the next in bancroftian filariasis is associated with increased frequency of ADL attacks.

Micro-spatial variation in filarial disease and risk of developing disease associated with microfilaremia in urban situation.

Clinical and parasitological surveys were carried out concurrently during 1986 in Pondicherry. The analyses showed that there was no significant micro-spatial variation in prevalence of total diseases (acute and chronic) and the manifestations such as hydrocele and lymphedema in the different zones and stations of Pondicherry urban area, a stable endemic area. Analyses on different filariometric indices in different stations showed a significant correlation between disease and mf prevalence (r = 0.4106; p = 0.037). The prevalence of disease and hydrocele in microfilaremic individuals (9.4% and 20.0% respectively) was higher compared to that observed in amicrofilaremic persons (6.4% and 11.2% respectively). The relative risk (RR) of parasite carriers developing disease (any manifestations) was marginally higher compared to amicrofilaremic persons (1.18). However, the RR of developing hydrocele manifestation due to microfilaremia was much greater (1.5) compared to amicrofilaremic persons. The attributable risk (AR) due to microfilaremia for developing hydrocele was 0.05. This suggests that although the risk is high in mf carriers, there might be alternate ways of developing disease without the infected person becoming microfilaremic. The limitations of point prevalence data on understanding complex dynamics of infection and disease are discussed.