Health status of lymphatic filariasis assessed from patients using seven domains five levels (7D5L) instrument

Health status is the standardized description of health condition of individuals either normal or ill due to diseases and is presented as multidimentional profiles. In an effort to develop an indicator to assess the impact of morbidity intervention against lymphatic filariasis (LF), we assessed the health status of seven different clinical manifestations (health states) of LF from the patient's perspective. One hundred and seventy-four filarial patients either with hydrocele or lymphoedema were involved in the study. Acute episode of adenolymphangitis (ADL) among chronic patients was considered as co-morbidity. Severity levels, focusing on physical, mental and social dimensions of health were defined and quantified, using seven domains and five levels (7D5L) instrument, an extended form of EuroQol (5D3L). All the seven domains of health are affected by filarial disease, with the levels of severity varying with health states. The mean severity score of ADL (25.8) was significantly higher compared to lymphoedema (10.7) and hydrocele (6.9) (P<0.05). In males, the mean score of lymphoedema (11.6) was significantly higher in comparison to hydrocele (P<0.05). The severity scores increase with the progression of filarial disease but independent of gender. The health states of LF were further classified based on the percentage of severity according to International Classification of Functioning, Disability and Health (ICF) on impairments. Lymphoedema grade 4 (oedema with skin changes) and ADL were ranked as severe. The importance of these findings is discussed in view of priority setting and evaluating the morbidity management under Global Programme for Elimination of Lymphatic Filariasis (GPELF).

Operational feasibility of lot quality assurance sampling (LQAS) as a tool in routine process monitoring of filariasis control programmes

Lot quality assurance sampling (LQAS) with two-stage sampling plan was applied for rapid monitoring of coverage after every round of mass drug administration (MDA). A Primary Health Centre (PHC) consisting of 29 villages in Thiruvannamalai district, Tamil Nadu was selected as the study area. Two threshold levels of coverage were used: threshold A (maximum: 60%; minimum: 40%) and threshold B (maximum: 80%; minimum: 60%). Based on these thresholds, one sampling plan each for A and B was derived with the necessary sample size and the number of allowable defectives (i.e. defectives mean those who have not received the drug). Using data generated through simple random sampling (SRSI) of 1,750 individuals in the study area, LQAS was validated with the above two sampling plans for its diagnostic and field applicability. Simultaneously, a household survey (SRSH) was conducted for validation and cost-effectiveness analysis. Based on SRSH survey, the estimated coverage was 93.5% (CI: 91.7-95.3%). LQAS with threshold A revealed that by sampling a maximum of 14 individuals and by allowing four defectives, the coverage was >or=60% in >90% of villages at the first stage. Similarly, with threshold B by sampling a maximum of nine individuals and by allowing four defectives, the coverage was >or=80% in >90% of villages at the first stage. These analyses suggest that the sampling plan (14,4,52,25) of threshold A may be adopted in MDA to assess if a minimum coverage of 60% has been achieved. However, to achieve the goal of elimination, the sampling plan (9, 4, 42, 29) of threshold B can identify villages in which the coverage is <80% so that remedial measures can be taken. Cost-effectiveness analysis showed that both options of LQAS are more cost-effective than SRSH to detect a village with a given level of coverage. The cost per village was US dollars 76.18 under SRSH. The cost of LQAS was US dollars 65.81 and 55.63 per village for thresholds A and B respectively. The total financial cost of classifying a village correctly with the given threshold level of LQAS could be reduced by 14% and 26% of the cost of conventional SRSH method.

Physical and psychosocial burden due to lymphatic filariasis as perceived by patients and medical experts

Patients with lymphatic filariasis (LF) face considerable physical, psychological and social disabilities. Morbidity management and control are important components of the Global Programme to Eliminate Lymphatic Filariasis. But information on the various disabilities caused by LF is scanty. We measured the severity levels of seven health states of LF in the physical and psychosocial domains of health from the perspective of patients and medical experts, using a 7-domain 5-level (7D5L) descriptive system. Adenolymphangitis had the highest severity levels in all domains of health followed by lymphoedema grade 4 (L4), lymphoedema grade 3 (L3), hydrocele grade 2 (H2), lymphoedema grade 2 (L2), lymphoedema grade1 (L1) and hydrocele grade 1 (H1). People with higher grades of lymphoedema and hydrocele had more severe psychosocial problems than physical ones. Severity levels assessed by medical experts were lower than those reported by sufferers. These findings indicate that LF has considerable impact on the physical, mental and social domains of health. Morbidity management programmes should be broadened to include counselling, rehabilitation and health education to manage the psychosocial problems caused by LF.

Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2.2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11-15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60-70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.

The dynamics ofWuchereria bancroftiinfection: a model-based analysis of longitudinal data from Pondicherry, India

This paper presents a model-based analysis of longitudinal data describing the impact of integrated vector management on the intensity ofWuchereria bancroftiinfection in Pondicherry, India. The aims of this analysis were (1) to gain insight into the dynamics of infection, with emphasis on the possible role of immunity, and (2) to develop a model that can be used to predict the effects of control. Using the LYMFASIM computer simulation program, two models with different types of immunity (anti-L3 larvae or anti-adult worm fecundity) were compared with a model without immunity. Parameters were estimated by fitting the models to data from 5071 individuals with microfilaria-density measurement before and after cessation of a 5-year vector management programme. A good fit, in particular of the convex shape of the age-prevalence curve, required inclusion of anti-L3 or anti-fecundity immunity in the model. An individual's immune-responsiveness was found to halve in ~10 years after cessation of boosting. Explanation of the large variation in Mf-density required considerable variation between individuals in exposure and immune responsiveness. The mean life-span of the parasite was estimated at about 10 years. For the post-control period, the models predict a further decline in Mf prevalence, which agrees well with observations made 3 and 6 years after cessation of the integrated vector management programme.

Novel label-free DNA sensors based on poly(3,4-ethylenedioxythiophene)Electronic Supplementary Information (ESI) available: Experimental details and sensor response for various sensors listed in Table 2. Cyclic voltammograms confirming the increase in resistance due to the duplex formation between the probe and target DNA in conducting polymer matrix. See http://www.rsc.org/suppdata/cc/b3/b316794a/

We report on the design and development of a novel label-free DNA sensor based on conducting poly(3,4-ethylenedioxythiophene) for the direct detection and quantification of target ssDNA.

Inferences on the common mean of several normal populations based on the generalized variable method

This article presents procedures for hypothesis testing and interval estimation of the common mean of several normal populations. The methods are based on the concepts of generalized p-value and generalized confidence limit. The merits of the proposed methods are evaluated numerically and compared with those of the existing methods. Numerical studies show that the new procedures are accurate and perform better than the existing methods when the sample sizes are moderate and the number of populations is four or less. If the number of populations is five or more, then the generalized variable method performs much better than the existing methods regardless of the sample sizes. The generalized variable method and other existing methods are illustrated using two examples.

Treatment seeking behaviour and costs due to acute and chronic forms of lymphatic filariasis in urban areas in south India

Previous estimates on the economic burden of lymphatic filariasis (LF) in India and elsewhere were primarily based on studies in rural areas. We investigated the treatment costs due to acute and chronic forms of LF in urban areas, where nearly one-third of the affected people live. Almost 98% of the patients with acute episodes of adenolymphangitis (ADL) underwent treatment and 49% of chronic patients also received treatment. The average treatment cost per ADL episode (n = 108) was Rs 22.21 +/- 53.84 (US dollars 0.46 +/- 1.12). The overall (n = 200) treatment costs incurred by a chronic patient per visit were Rs 16.71 +/- 62.36 (US dollars 0.35 +/- 1.30); for those who paid (n = 98) they were Rs 34.10 +/- 85.90 (US dollars$ 0.71 +/- 1.79). These costs are considerably higher than in rural areas. Government health centres and private practitioners were important sources of treatment. Treatments received from private practitioners were considerably more expensive than those from government health facilities. The cost of medicine accounted for 44% and 50% of the total expenditure on treatment for acute and chronic disease patients, respectively. The medical personnel from these treatment sources need to be trained on the new morbidity management methods, which are likely to be more effective than the current methods of treatment.

Cost-effectiveness of the use of vector control and mass drug administration, separately or in combination, against lymphatic filariasis

The costs and effects of two intervention strategies for the control of bancroftian filariasis-annual mass drug administrations (MDA) with a combination of diethylcarbamazine and ivermectin, with or without integrated vector control (VC)-were estimated in rural villages in South India. The aim was to compare the cost-effectiveness of MDA alone with that of MDA plus VC. Control of the local vector, Culex quinquefasciatus, was based on the application of polystyrene beads to cesspits, the treatment of drains with larvicidal Bacillus sphaericus and the stocking of wells with larvivorous fish. An itemized cost menu was used to cost MDA and MDA + VC, retrospectively. The annual transmission potential was used to assess the direct outcome of the disease-control methods, whereas the prevalence and intensity of microfilaraemia were used as indicators of the impact of each method. The per-capita costs were 1.49 U.S. dollars for two rounds of MDA, 1.70 U.S. dollars for 2 years of VC and, therefore, 3.19 U.S. dollars for 2 years of MDA + VC. Integration of VC with MDA did not appear to be cost-effective: it cost an estimated 1.80 U.S. dollars to stop an infective mosquito biting a villager using MDA alone but 3.32 U.S. dollars to achieve the same result using MDA + VC. Similarly, the cost to reduce the prevalence of microfilaraemia in a three-village group by 1% was only 96.62 U.S. dollars for MDA alone but 201.16 U.S. dollars when vector control was integrated. The implications of these results for the control and elimination of filariasis in Indian village communities, and the options for sharing and minimizing costs, are discussed.

Statistical methods for establishing equivalency of a sampling device to the OSHA standard

Occupational Safety and Health Administration (OSHA) regulations allow the use of an alternative sampling device for exposure monitoring provided the device has been demonstrated to be equivalent to the standard device. For example, the OSHA standard allows the use of an alternate cotton dust sampler that is equivalent to the Lumsden-Lynch vertical elutriator (VE); also, OSHA defines the accuracy of the monitoring device for measuring airborne chemicals such as benzene and sulfur dioxide. Typically, the OSHA criterion is that 90% of the readings of the sampling device should be within +/- 25% of the readings obtained by the standard device or within +/- 25% of the actual airborne chemical concentration. This article proposes two statistical tests for establishing that an alternative measuring device of airborne chemicals or dust is equivalent to the OSHA standard. The statistical tests are illustrated using an example.