Diethylcarbamazine citrate-fortified salt for lymphatic filariasis elimination in India

Lymphatic filariasis (LF) is a vector-borne neglected tropical disease, causing permanent disability. The disease is debilitating and widespread, leading to tremendous productivity and economic loss. The Government of India (GOI) prioritized the elimination of LF through the annual mass drug administration (MDA) programme in 2004 and continued with a single dose of diethylcarbamazine citrate (DEC), 6 mg/kg of body weight, plus albendazole annually over a period of 5-6 years. The GOI had set the target to achieve LF elimination by 2015 and now by 2030. The progress so far has been suboptimal. Much remains to be done as about 84 per cent of the total 328 endemic districts are still under MDA. The major challenge in implementing MDA is poor compliance. It is necessary to have a feasible alternative strategy addressing the above challenge to achieve the desired goal of LF elimination. At this juncture, a well-researched approach, i.e. the use of DEC-fortified salt, also advocated by the World Health Organization, as a unique form of MDA, is proposed. As per this strategy, a low dose of DEC (0.2% w/w) is added to the cooking salt at the manufacturing facility of iodized salt and consumed by the LF-endemic communities for about two years. Many examples of successful use of this strategy for LF elimination in small- and large-scale trials have been documented in India and several other endemic countries in the world. Implementing DEC-iodine-fortified salt is a safe, less expensive, more efficient and prompt approach for achieving the elimination of LF in India. Adverse effects are none or minor and self-limiting. The DEC-fortified salt strategy can easily piggyback on the existing countrywide deployment of iodized salt under the National Iodine Deficiency Disorders Control Programme (NIDDCP), which has achieved a great success in reducing iodine-deficiency disorders such as hypothyroidism. This existing robust programme can be leveraged to launch DEC-fortified salt for the community. If implemented appropriately, this strategy will ensure the complete cessation of LF transmission within two years from its introduction. If the said strategy is implemented in 2022, it is expected that India will be able to achieve the LF elimination by 2024, much before the global target of 2030.

Dengue vector abundance and diversity of breeding habitats in Puducherry, South India

Puducherry had reported regular dengue outbreaks since 2003 with many-fold increase in number of cases every year. This study was done to assess the intensity of dengue vector breeding and diversity of breeding habitats. Aedes surveys were conducted in 8 Primary Health Centres (PHCs) representing both rural and urban areas of Puducherry district throughout the year 2012. Containers inside and outside randomly (simple) selected houses and vacant sites around houses were examined for presence of Aedes mosquitoes. The containers containing water with immature larvae were designated as positive containers (PC), while the containers holding only water were designated as wet containers and all the larvae/pupae from the positive containers were collected and entomological indices were determined using standard WHO methods. The vectors, Aedes aegypti and Ae. albopictus were encountered in the survey, with Ae. aegypti present in high numbers in urban as well as rural areas. The plastic containers were found as the most productive indoor breeding habitat as the 27.2% of the total pupae collected was contributed by plastic containers followed by flower vase (22.8%) and grinding stone (17.6%). Larval indices were found to vary throughout the year and highest indices were recorded during the months of October and November indicating the potential risk of dengue fever during this period.

Health-related quality of life among Indigenous Australians diagnosed with cancer

PURPOSE

Health-related quality of life (HRQoL) and associated factors were assessed among 155 Indigenous Australian adult cancer patients 6 months post-diagnosis.

METHODS

The Assessment of Quality of Life-4D Questionnaire was used to assess HRQoL. Differences in the median utility score among subgroups of interest were examined using nonparametric tests. Factors associated with excellent HRQoL were assessed through logistic regression.

RESULTS

Participants' mean age was 52 years (range 20-78), and the majority were female (60 %), unemployed (72 %), and recruited from outpatients clinics (64 %). Breast cancer (27 %) was the most common diagnosis. The median HRQoL score was 0.62; 14 % of participants reported excellent HRQoL (>0.90). After adjusting for age, admission status, and treatment, excellent HRQoL was more likely among participants of Torres Strait Islander origin [adjusted odds ratio (AOR) 3.68; 95 % CI 1.23-11.01], those living in regional areas (AOR 5.59; 95 % CI 1.42-22.06), and those whose main language spoken at home was not English (AOR 3.60; 95 % CI 1.08-11.99) and less likely among those reporting less contact with Indigenous people (AOR 0.23; 95 % CI 0.68-0.81).

CONCLUSION

Assessing HRQoL is important to identifying and improving the length and quality of cancer survivorship, especially in groups that have significantly poorer cancer outcomes, such as Indigenous Australians. Acknowledging the study's observational nature, we found HRQoL was lower than reported for other Australians, and we identified some socio-demographic factors that were associated with excellent HRQoL. Such assessments are an important component of identifying and evaluating appropriate interventions to improve the health and well-being of Indigenous cancer patients.

Remote chemotherapy supervision model for rural cancer care: perspectives of health professionals

Townsville Cancer Centre (TCC), a tertiary cancer centre in North Queensland, Australia, provides chemotherapy services to surrounding small rural towns using the Queensland Remote Chemotherapy Supervision model (QReCS). Under this model, selected chemotherapy regimens are administered in rural hospitals by rural based generalist doctors and nurses, under the supervision of TCC-based medical oncologists and chemotherapy competent nurses through videoconferencing. We sought to explore the perspectives of health professionals participating in QReCS. This qualitative study used semi-structured interviews with 19 participants, including nine nurses, eight doctors, one rural pharmacist and one administration officer. The interviews were recorded and transcribed. Transcripts were examined using iterative thematic analysis. Four major themes were identified from the data: (1) benefits of the model, (2) enablers of implementation, (3) operational requirements for optimal functioning and (4) disadvantages of the model. The reported benefits of the model were patient convenience, inter-professional communication across health district borders, expanded scope of practice, continuity of care and maintenance of patient safety and compliance with guidelines while delivering chemotherapy. Further improvements in the quality of training for rural nurses, coordination between urban and rural sites and between health professionals and documentation of clinical encounters would optimise the operation of the model. QReCS appears to provide many benefits to patients and health professionals and a framework for safe administration of chemotherapy in rural areas. Coordination of care, the quality of training for rural nurses as well as clinical documentation needs to improve to optimise the operation of the model.

Predatory potential of Platynectes sp. (Coleoptera: Dytiscidae) on Aedes albopictus, the vector of dengue/chikungunya in Kerala, India

Unused and discarded latex collection containers (LCCs) are the major breeding habitats of Aedes albopictus in the rubber plantations of Kerala, India. Platynectes sp. (Family: Dytiscidae) was observed to invade these habitats during the monsoon season and voraciously devour the larval instars of this major vector species of arbo-viral diseases. Field observations showed a reduction of 70.91% (p = 0.0017) and 100% in Aedes larval density, on the first and four days post release of eight beetles per LCC respectively. In laboratory, a beetle was found to devour 17.75 + 5.0 late larval instars of Ae. albopictus per day. Our findings indicate Platynectes sp. could be a potential bio-control agent against Ae. albopictus, the vector of chikungunya/dengue fevers, in rubber plantations.

Practical aspects of telehealth: doctor-patient relationship and communication

The fourth in a series of articles about the practical aspects of telehealth, this paper provides advice and information for specialists to communicate effectively with patients during a telehealth video consultation.

Practical aspects of telehealth: set-up and preparation for video consultations

The third in a series of articles about the practical aspects of telehealth, this paper gives guidance on suitable setup for video consultations, including layout of rooms, managing sound and image quality, scheduling, testing and best practice in telehealth videoconferencing.

Practical aspects of telehealth: are my patients suited to telehealth?

The first in a series of articles that demonstrate the practical aspects of telehealth, this paper provides three case studies that examine the suitability of telehealth for patients living in rural and remote areas who require ongoing specialist care.

Telerheumatology: an idea whose time has come

Australia is a vast country with one-third of the population living outside capital cities. Providing specialist rheumatologist services to regional, rural and remote Australians has generally required expensive and time-consuming travel for the patient and/or specialist. As a result, access to specialist care for remote Australians is poor. Rheumatoid arthritis is a common disease, but like many rheumatic diseases, it is complex to treat. Time-dependent joint damage and disability occur unless best evidence care is implemented. The relatively poor access to rheumatologist care allotted to nonmetropolitan Australians therefore represents a significant cause of potentially preventable disability in Australia. Telehealth has the potential to improve access to specialist rheumatologists for patients with rheumatoid arthritis and other rheumatic diseases, thereby decreasing the burden of disability caused by these diseases. Advances in videoconferencing technology, the national broadband rollout and recent Federal government financial incentives have led to a heightened interest in exploring the use of this technology in Australian rheumatology practice. This review summarises the current evidence base, outlines telehealth's strengths and weaknesses in managing rheumatic disease, and discusses the technological, medicolegal and financial aspects of this model of care. A mixed model offering both face-to-face and virtual consultations appears to be the best option, as it can overcome the barriers to accessing care posed by distance while also mitigating the risks of virtual consultation.

Medical oncology clinics through videoconferencing: an acceptable telehealth model for rural patients and health workers

BACKGROUND

Since 2007, Townsville Cancer Centre (Queensland, Australia) has provided routine and urgent medical oncology services to rural and remote communities through videoconferencing. At remote sites, patients were accompanied by doctors and other health workers. The aim of this study was to describe satisfaction of patients and rural health workers with this model of teleoncology.

METHODS

Between May 2007 and June 2010, 55 videoconferencing patients were invited to participate in a questionnaire-based telephone survey after informed consent. The survey included responses to 16 satisfaction statements using a 5-point Likert scale. Perspectives of health workers involved were recorded using open-ended questions on six themes related to telehealth.

RESULTS

Among the 50 participating cancer patients, median age was 56 years (range 28-83). Seventy-six per cent of patients thought specialist physical examination was important despite local doctors performing it. Seventy-six per cent of patients felt the presence of accompanying local health workers was not important. Seventy-eight per cent of patients preferred to be seen in Mt Isa for the first consultation through videoconferencing than travelling to Townsville. More than 80% of patients were in agreement with the rest of the satisfaction statements. Ninety-six per cent of patients were in agreement with the question relating to overall satisfaction. Eighteen health workers participated and their responses and attitudes were favourable towards telehealth.

CONCLUSION

Satisfaction with this model of care was proven to be high among both patients and health workers. Benefits perceived included effective communication between patients and specialists, reduced travel time and money expenditure, and superior specialist support for rural health workers.

DNA Barcodes indicate members of the Anopheles fluviatilis (Diptera: Culicidae) species complex to be conspecific in India

Anopheles fluviatilis, a major vector of malaria in India has been described as a complex of three sibling species members, named as S, T and U, based on variations in chromosomal inversions. Also, ribosomal DNA markers (repetitive Internal Transcribed Spacer 2 (ITS2) and 28S D3 region) were described to differentiate these three sibling species members. However, controversies prevail on the genetic isolation status of these cryptic species. Hence, we evaluated this taxonomic incongruence employing DNA barcoding, the well established methodology for species identification, using 60 An. fluviatilis sensu lato specimens, collected from two malaria endemic eastern states of India. These specimens were also subjected to sibling species characterization by ITS2 and D3 DNA markers. The former marker identified 31 specimens among these as An. fluviatilis S and 21 as An. fluviatilis T. Eight specimens amplified DNA fragments specific for both S and T. The D3 marker characterized 39 specimens belonging to species S and 21 to species T. Neither marker identified species U. Neighbor Joining analysis of mitochondrial cytochrome c oxidase gene 1 sequences (the DNA barcode) categorized all the 60 specimens into a single operational taxonomic unit, their Kimura 2 parameter (K2P) genetic variability being only 0.8%. The genetic differentiation (FST ) and gene flow (Nm ) estimates were 0.00799 and 62.07, respectively, indicating these two 'species' (S & T) as genetically con-specific intermixing populations with negligible genetic differentiation. Earlier investigations have refuted the existence of species U. Also, this study demonstrated that An. fluviatilis and the closely related An. minimus could be taxonomically differentiated by the DNA Barcode approach (K2P = 5.0%).

Invasion of toxic marine cyanobacteria in to the tsunami affected coastal villages of southern India

This documentation explores the facts about the invasion of marine cyanobacteria in to the tsunami affected coastal villages of Nagapattinam district of Tamilnadu and Karaikkal district of Pondicherry Union Territory (UT) in southern India. Water samples were collected from eight tsunami-hit coastal villages in different open water sources. The collected samples were processed for detecting marine cyanobacterial growth. Totally 110 water samples were processed, three samples were positive for the toxic cyanobacteria, Lyngbya sp., and nine for nontoxic species such as Epithemia sp.,, Johannesbaptistia pellucida, Oscillatoria princeps, Phormidium fragile, Synechocystis sp. Besides posing a public health risk because of the toxic cyanobacteria, the bloom formation by the cyanobacterial species such as Anabaena, Microcystis, Lyngbya, Plectonema, Phormidium contaminated the water bodies and deteriorated the water quality in the tsunami affected villages. The study revealed that another kind of public health risk from the invasion of toxic cyanobacteria to the costal ecosystem during the tsunami. It is necessary, in this context, that the surveillance mechanism, which is geared up during or after natural disasters, should have a provision to monitor the transportation of toxic elements/organisms from marine system to coastal/inland ecosystems and to control such organisms.

Laboratory evaluation of dimethyl phthalate treated wristbands against three predominant mosquito (Diptera: Culicidae) vectors of disease

OBJECTIVES AND MATERIALS AND METHODS: The repellent efficacy of dimethyl phthalate (DMP) treated wristband was determined against mosquitoes, viz Anopheles stephensi Liston, Aedes aegypti Linnaeus, Culex quinquefasciatus Say at two concentrations viz., 1.5 and 2.0 mg/cm2 under the laboratory conditions. DMP treated wristband had shown variable degrees of repellency impact against different mosquito species.

RESULTS

Its offered higher reduction of man landing rate against Anopheles stephensi at both concentrations of 1.5 (81.1%) and 2.0 mg/cm2 (87.0%). 79.8% and 84.8% of protection achieved against Culex quinquefasciatus at concentrations of 1.5 and 2.0 mg/cm2, respectively. 74.4 and 86.5% of reduction of man landing rates were obtained against Aedes aegypti at concentrations of 1.5 and 2.0 mg/cm2 respectively. The reduction of man-landing rate evaluations were confirmed by t-test compared between control group and each experimental group. The t-test result shows at 1.5 (p = 0.0026; t = 19.2; df = 2) as well 2.0 mg/cm2 (p = 0.0025; t = 19.8; df = 2) are extremely significant to reduce the man vector contact.

CONCLUSION

The present data suggest that DMP treated wristbands are most promising against both day and night-biting mosquitoes and significantly reducing the man-vector contact. Therefore, it could serve as a potential as means of personal protection device against insect nuisance biting and insect-borne disease when and where other kinds of personal protection measures are impossible and impracticable.

Video linked medical oncology clinics: A novel way to improve patients’ access to medical oncology services in rural Australia

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Background: To improve the access of Mt Isa patients to medical oncologists, Townsville Cancer Centre runs weekly medical oncology clinics via videolink. Aim of this study was to assess patient satisfaction, safety of chemotherapy delivery, and cost effectiveness of such technology. Methods: Between 2006 and 2008, 42 patients were seen. A questionnaire based survey was conducted by telephone to assess patient's level of satisfaction and quality of communication. Safety of chemotherapy delivery was evaluated by retrospective chart audit. Results: 25 patients completed the questionnaire. Six were new patients and the rest were for review leading to more than 90 encounters. Satisfaction: 100% of those interviewed were satisfied with the care given by the Townsville Cancer Centre. Of these 88% felt they developed a friendly relationship with the specialist. 90% felt medication could be taken without any concerns after videolink. 27% of patients interviewed felt examination was needed by the specialist, but 92% of the patients would rather see the specialist via videolink than travel to Townsville. Overall 96% felt it saved time, money and was convenient. Responses, apart from the question about the need for physical examination by the specialist, were more than 80% in agreement. Safety: 32 patients received active therapy. 60% were treated with palliative intent and the rest adjuvant. The median number of cycles was 5 (1–8). A total of 4 patients were admitted for complications- 2 for febrile neutropenia and 2 for emesis.There were no treatment related deaths. Cost effectiveness: Factors for consideration were cost of patient and specialist travel and accommodation,cost of interruption of routine clinics at specialists’ home, cost of video link apparatus and maintenance and cost of disturbance of quality of life for patients and doctors resulting from travel. Conclusions: Satisfaction with video linked clinics is high. It saves travel time for the patients and specialists and seems to be cost effective. It is safe to supervise chemotherapy administration using this technology. Therefore, this method of service delivery could be adopted by medical oncology departments to improve services to the rural and remote areas.

No significant financial relationships to disclose.

Brain dynamical disentrainment by anti-epileptic drugs in rat and human status epilepticus

In this paper, we utilize a measure of brain dynamics, namely the short-term largest Lyapunov exponent (STLmax) to evaluate the efficacy of treatment in epileptic animals and humans with known antiepileptic drugs (AED) like diazepam and phenobarbital during status epilepticus (SE). This measure is estimated from analysis of electroencephalographic (EEG) recordings at multiple brain locations in both an SE patient and a cobalt/homocysteine thiolactone SE-induced animal. Techniques from optimization theory and statistics are applied to select optimal sets of brain sites, whose dynamics are then measured over time to study their entrainment/disentrainment. Results from such analysis indicate that the observed abnormal spatio-temporal dynamical entrainment in SE is reversed by AED administration (resetting of brain dynamics). These results may provide a potential use of nonlinear dynamical measures in the evaluation of the efficacy of AEDs and the development of new treatment strategies in epilepsy.

Detection of Brugia malayi in laboratory and wild-caught Mansonioides mosquitoes (Diptera: Culicidae) using Hha I PCR assay

An Hha 1 based polymerase chain reaction (PCR) assay developed for the detection of Brugia malayi, the causative agent of Brugian lymphatic filariasis, was evaluated for its sensitivity in the laboratory and for its usefulness in measuring changes in transmission of the disease in the field. Laboratory studies showed that the new assay was highly sensitive in comparison with the standard dissection and microscopy technique. The assay can detect as little as 4 pg of parasite DNA or a single microfilaria in pools of up to 100 mosquitoes. The optimum pool size for convenience was found to be 50 mosquitoes per pool. The efficacy of PCR assay was evaluated in filariasis control programmes in operation in endemic areas of Kerala State, South India. The infection rates obtained by the Hha I PCR assay and the conventional dissection and microscopy technique were 1.2% and 1.7% respectively in operational areas and 8.3% and 4.4% respectively, in check areas, which were not significantly different (P < 0.05). Thus, the Hha I PCR assay was found to be as sensitive as the conventional technique and hence it can be used as a new epidemiological tool for assessing parasite infection in field-collected mosquitoes.

Mapping of lymphatic filariasis in India

The derivation of detailed epidemiological maps, at the relevant spatial resolution, is being increasingly recognized as vital to the effective design and implementation of successful programmes for the control of parasites and their vectors. Geographical information systems (GIS) and a recently complied database on the distribution of lymphatic filariasis in India have now been used to develop the first maps at district-level (i.e. the level at which control against this parasite will be enacted in India) of filariasis endemicity in this country. The derived maps indicate both the substantial extent as well as the marked variability in the geographical distribution of this disease in India. The causative infection and/or the symptomatic disease were detected in most (257) of the 289 districts surveyed up to 1995. Currently there may be up to 27.09 million microfilaraemics, 20.83 million cases of symptomatic filariasis, and about 429.32 million individuals potentially at risk of infection in the country. Probability mapping, based on data quantiles, clearly indicates that the risk of filarial infection in India is not constant throughout the country but exhibits strong regional trends. Filariasis in general may be a particular problem of the eastern half of the country. The results indicate the potentially vital role that GIS-based mapping approaches can play in the development of filariasis-control campaigns in India and elsewhere.

Susceptibility status of Mansonia annulifera to Brugia malayi parasites in Cherthala, Alappuzha district, Kerala

Laboratory studies conducted on Ma. annulifera collected from Cherthala region, Kerala, endemic for Brugian filariasis indicated that this species is highly susceptible to B. malayi parasites. The experimental infection index of this species was relatively higher (2.74). No significant loss of larvae during development was recorded. The extrinsic incubation period was estimated to be 8 days.

X-ray crystallographic studies of unique cross-linked lattices between four isomeric biantennary oligosaccharides and soybean agglutinin

Soybean agglutinin (SBA) (Glycine max) is a tetrameric GalNAc/Gal-specific lectin which forms unique cross-linked complexes with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal GalNAc or Gal residues [Gupta et al. (1994) Biochemistry 33, 7495-7504]. We recently reported the X-ray crystal structure of SBA cross-linked with a biantennary analog of the blood group I carbohydrate antigen [Dessen et al. (1995) Biochemistry 34, 4933-4942]. In order to determine the molecular basis of different carbohydrate-lectin cross-linked lattices, a comparison has been made of the X-ray crystallographic structures of SBA cross-linked with four isomeric analogs of the biantennary blood group I carbohydrate antigen. The four pentasaccharides possess the common structure of (beta-LacNAc)2Gal-beta-R, where R is -O(CH2)5COOCH3. The beta-LacNAc moieties in the four carbohydrates are linked to the 2,3-, 2,4-, 3,6-, and 2,6-positions of the core Gal residue(s), respectively. The structures of all four complexes have been refined to approximately 2.4-2.8 A. Noncovalent lattice formation in all four complexes is promoted uniquely by the bridging action of the two arms of each bivalent carbohydrate. Association between SBA tetramers involves binding of the terminal Gal residues of the pentasaccharides at identical sites in each monomer, with the sugar(s) cross-linking to a symmetry-related neighbor molecule. While the 2,4-, 3,6-, and 2,6-pentasaccharide complexes possess a common P6422 space group, their unit cell dimensions differ. The 2, 3-pentasaccharide cross-linked complex, on the other hand, possesses the space group I4122. Thus, all four complexes are crystallographically distinct. The four cross-linking carbohydrates are in similar conformations, possessing a pseudo-2-fold axis of symmetry which lies on a crystallographic 2-fold axis of symmetry in each lattice. In the case of the 3,6- and 2,6-pentasaccharides, the symmetry of their cross-linked lattices requires different rotamer orientations about their beta(1,6) glycosidic bonds. The results demonstrate that crystal packing interactions are the molecular basis for the formation of distinct cross-linked lattices between SBA and four isomeric pentasaccharides. The present findings are discussed in terms of lectins forming unique cross-linked complexes with glycoconjugate receptors in biological systems.

X-ray crystallographic studies of unique cross-linked lattices between four isomeric biantennary oligosaccharides and soybean agglutinin

Soybean agglutinin (SBA) (Glycine max) is a tetrameric GalNAc/Gal-specific lectin which forms unique cross-linked complexes with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal GalNAc or Gal residues [Gupta et al. (1994) Biochemistry 33, 7495-7504]. We recently reported the X-ray crystal structure of SBA cross-linked with a biantennary analog of the blood group I carbohydrate antigen [Dessen et al. (1995) Biochemistry 34, 4933-4942]. In order to determine the molecular basis of different carbohydrate-lectin cross-linked lattices, a comparison has been made of the X-ray crystallographic structures of SBA cross-linked with four isomeric analogs of the biantennary blood group I carbohydrate antigen. The four pentasaccharides possess the common structure of (beta-LacNAc)2Gal-beta-R, where R is -O(CH2)5COOCH3. The beta-LacNAc moieties in the four carbohydrates are linked to the 2,3-, 2,4-, 3,6-, and 2,6-positions of the core Gal residue(s), respectively. The structures of all four complexes have been refined to approximately 2.4-2.8 A. Noncovalent lattice formation in all four complexes is promoted uniquely by the bridging action of the two arms of each bivalent carbohydrate. Association between SBA tetramers involves binding of the terminal Gal residues of the pentasaccharides at identical sites in each monomer, with the sugar(s) cross-linking to a symmetry-related neighbor molecule. While the 2,4-, 3,6-, and 2,6-pentasaccharide complexes possess a common P6422 space group, their unit cell dimensions differ. The 2, 3-pentasaccharide cross-linked complex, on the other hand, possesses the space group I4122. Thus, all four complexes are crystallographically distinct. The four cross-linking carbohydrates are in similar conformations, possessing a pseudo-2-fold axis of symmetry which lies on a crystallographic 2-fold axis of symmetry in each lattice. In the case of the 3,6- and 2,6-pentasaccharides, the symmetry of their cross-linked lattices requires different rotamer orientations about their beta(1,6) glycosidic bonds. The results demonstrate that crystal packing interactions are the molecular basis for the formation of distinct cross-linked lattices between SBA and four isomeric pentasaccharides. The present findings are discussed in terms of lectins forming unique cross-linked complexes with glycoconjugate receptors in biological systems.

Current status of filariasis in Chavakad taluk, Trichur district, Kerala

A sample survey using parasitological, clinical and entomological indicators was carried out in all the 18 administrative units of Chavakad taluk, Trichur district, Kerala, India to assess the current filariasis situation. Cluster sampling procedure was followed to screen individuals. Both Wuchereria bancrofti and Brugia malayi species were found to be prevalent in this taluk. Microfilaria (mf) carriers with W. bancrofti were detected in eight areas while B. malayi was recorded only from one area. The two species were found to co-exist in another area. The highest infection rate registered for W. bancrofti was 1.51 while it was 0.3 for B. malayi. Infection due to W. bancrofti constituted 87.88% of the total 33 microfilaria cases. Prevalence of B. malayi was very low. Cases with clinical manifestation of filariasis were recorded in all the four areas surveyed. The present trend in the prevalence of infection (mf) and disease showed a decline in both the species when compared to earlier surveys of 1960s. At least 11 areas are still endemic for filariasis in this taluk. Although prevalence of mf was recorded for the first time in one of the areas viz., Elavalli, the rate was only 0.16%. Entomological surveys revealed the presence of 14 mosquito species, of which Culex quinquefasciatus contributed 84.85% and Mansonia 0.77%. While C. quinquefasciatus was recorded in all the 18 areas, Mansonia spp were found only in 8 areas. Only C. quinquefasciatus was found to harbour different developmental stages of W. bancrofti, with overall infection and infectivity rates of 1.94 and 0.97 respectively. The possible reason for the decline in vector density and infection in man are postulated.

Efficacy of diethylcarbamazine-medicated salt for microfilaraemia of Brugia malayi

BACKGROUND

Pilot studies in India and abroad have demonstrated the benefit of cooking salt fortified with diethylcarbamazine citrate (DEC) for the control of lymphatic filariasis. In India, DEC-medicated salt has been introduced on a commercial basis in the Cherthala region of Kerala, which is endemic for Brugia malayi (B. malayi). We studied the efficacy of DEC-medicated salt in the clearance of microfilaraemia of B. malayi.

METHODS

Eighteen cases of microfilaraemia (11 men; 7 women) were selected; 14 in the experimental group (i.e. treated with 0.2% w/w DEC-medicated salt) and the rest as the control group who were given a placebo. The consumption of salt and the status of parasitaemia were monitored till all the microfilaria carriers became negative.

RESULTS

There was a significant reduction in the density of microfilariae (intensity) among the treated individuals over a period of time. The duration required for the clearance of microfilariae ranged from 9 to 30 [mean (SD) 19.4 (1.7)] weeks. All microfilaraemics except one reported side-effects which were mild-to-moderate and persisted for a maximum period of one month.

CONCLUSION

DEC-medicated salt effectively clears microfilariae within 30 weeks in parasitaemic individuals. No 'endemic normals' reported any side-effects, though these were common among the microfilaria carriers.

Binding of the influenza A virus to cell-surface receptors: structures of five hemagglutinin-sialyloligosaccharide complexes determined by X-ray crystallography

The structures of five complexes of the X-31 influenza A (H3N2) virus hemagglutinin with sialyloligosaccharide receptor analogs have been determined from 2.5 to 2.8 A resolution by X-ray crystallography. There is well-defined electron density for three to five saccharides in all five complexes and a striking conformational difference between two linear pentasaccharides with the same composition but different linkage [alpha(2-->6) or alpha(2-->3)] at the terminal sialic acid. The bound position of the terminal sialic acid (NeuAc) is the same in all five complexes and is identical to that reported previously from the study of mono- and trisaccharides. The two oligosaccharides with NeuAc alpha(2-->6)Gal linkages and GlcNAc at the third position have a folded conformation with the GlcNAc doubled back to contact the sialic acid. The pentasaccharide with a terminal NeuAc alpha(2-->3)Gal linkage and GlcNAc at the third position has an extended (not folded) conformation and exits from the opposite side of the binding site than the alpha(2-->6)-linked molecule of the same composition. The difference between the conformation of the pentasaccharide with a 2,6 linkage and the trisaccharide 2,6-sialyllactose suggests that 2,6-sialyllactose is not, as previously believed, an appropriate analog of natural influenza A virus receptors. The oligosaccharides studied are NeuAc alpha(2-->3)Gal beta(1-->4)Glc, NeuAc alpha(2-->6)Gal beta(1-->4)Glc, NeuAc alpha(2-->3)Gal beta(1-->3)GlcNAc beta(1-->3)Gal beta(1-->4)Glc, NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc beta(1-->3)Gal beta(1-->4)Glc, and [NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc]2 beta(1-->3/6)Gal-beta-O-(CH2)5-COOCH3.

Field evaluation of biodegradable controlled release formulation of fenthion against Mansonia mosquitos

Controlled release monolithic formulation of fenthion, an organophosphorus mosquito larvicide, prepared by the physical entrapment of the active agent into biodegradable polymer matrices was evaluated against Mansonia mosquito larvae breeding in hydrophytes infested coconut husk retting ponds. Field evaluation was carried out at two application rates viz, 2.5 and 1.0 ppm. Absolute control of larval breeding was observed for 25 and 17 weeks and over 50% reduction in breeding density was observed for another 3 and 2 weeks for the respective application rates of 2.5 and 1.0 ppm. The bioassay carried out with the water samples collected from the ponds treated at 2.5 ppm against the fourth instar larvae of Mansonia annulifera showed larval mortality of more than 95% for 14 weeks and 80-95% from 15 to 25th week. The concentration of fenthion in the treated ponds was found to vary between 0.006 and 0.095 ppm during the evaluation period.

Mattancherry urban agglomeration, a diminishing focus of lymphatic filariasis in Kerala

Parasitological survey conducted recently in Mattancherry, Kerala showed a low prevalence of microfilariae (mf), with a mf rate of 1.81%, compared to that of 1956 when the mf rate was 14.7%. No brugian infection was encountered in the present investigation, though both bancroftian and brugian infections were reported earlier. Culex quinquefasciatus, the vector of bancroftian filariasis was the most predominant (93.3%) mosquito species, and its infection and infectivity rates were 0.76% and 0.54% respectively. Mansonioides spp., the vectors of brugian filariasis constituted only 0.2% of the total mosquitoes and with no infection. The overall reduction in the prevalence of mf cases and vector infection rates over the years is attributed to the continued activities of the National Filaria Control Programme. The disappearance of brugian filariasis could mainly be due to the drastic reduction in the Mansonioides breeding habitats, as a result of rapid urbanization coupled with improved socio economic conditions.

Brackish water mosquito problem of Vypeen Island, Cochin, Kerala

A preliminary study has shown that the marshy terrain and brackish water bodies associated with mangrove forests contributed profuse breeding of mosquitos in Vypeen island, causing a severe menace to the island population. A total of 14 species belonging to four genera viz, Aedes, Anopheles, Armigeres and Culex was recorded from different habitats. Culex sitiens was found to be the predominant mosquito in all the perennial breeding habitats. The extent of different habitats in the production of mosquitos, and its possible abatement, using environmental and/or biocontrol methods are discussed.

X-ray crystal structure of the soybean agglutinin cross-linked with a biantennary analog of the blood group I carbohydrate antigen

Soybean agglutinin (SBA) (Glycine max), which is a tetrameric GalNAc/Gal-specific lectin, has recently been reported to form unique, highly organized cross-linked complexes with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal GalNAc or Gal residues [Gupta, D., Bhattacharyya, L., Fant, J., Macaluso, F., Sabesan, S., & Brewer, C. F. (1994) Biochemistry 33, 7495-7504]. In order to elucidate the nature of these complexes, the X-ray crystallographic structure of SBA cross-linked with a biantennary analog of the blood group I carbohydrate antigen is reported. The structure reveals that lattice formation is promoted uniquely by the bridging action of the bivalent pentasaccharide (beta-LacNAc)2Gal-beta-R, where R is -O(CH2)5COOCH3 and the beta-LacNAc moieties are linked to the 2 and 6 positions of the core Gal. The structure of SBA complexed with the synthetic biantennary pentasaccharide has thus been determined by molecular replacement techniques and refined at 2.6 A resolution to an R value of 20.1%. The crystals are hexagonal with a P6(4)22 space group, which differs significantly from that of crystals of the free protein. In the structure, each monomeric asymmetric unit contains a Man9 oligomannose-type chain at Asn 75, with only the first two GlcNAc residues visible. The overall tertiary structure of the SBA subunit is similar to that of other legume lectins as well as certain animal lectins. However, the dimer interface in the SBA tetramer is unusual in that only one complete peptide chain is sterically permitted, thus requiring juxtapositioning of one C-terminal fragmented subunit together with an intact subunit. Association between SBA tetramers involves binding of the terminal Gal residues of the pentasaccharide at identical sites in each monomer, with the sugar cross-linking to a symmetry-related neighbor molecule. The cross-linking pentasaccharide is in a conformation that possesses a pseudo-2-fold axis of symmetry which lies on a crystallographic 2-fold axis of symmetry of the lattice. Hence, the symmetry properties of the bivalent oligosaccharide as well as the lectin are structural determinants of the lattice. The results are discussed in terms of multidimensional carbohydrate-lectin cross-linked complexes, as well as the signal transduction properties of multivalent lectins.

Characterization of sialyloligosaccharide binding by recombinant soluble and native cell-associated CD22. Evidence for a minimal structural recognition motif and the potential importance of multisite binding

CD22, a B cell-specific receptor of the immunoglobulin superfamily, has been demonstrated to bind to oligosaccharides containing alpha 2-6-linked sialic acid (Sia) residues. Previously, we demonstrated that the minimal structure recognized by this lectin is the trisaccharide Sia alpha 2-6Gal beta 1-4GlcNAc, as found on N-linked, O-linked, or glycolipid structures (Powell, L., and Varki, A. (1994) J. Biol. Chem. 269, 10628-10636). Here we utilize a soluble immunoglobulin fusion construct (CD22Rg) to determine directly by equilibrium dialysis the stoichiometry (2:1) and dissociation constant (32 microM) for Neu5Ac alpha 2-6Gal beta 1-4Glc binding. Inhibition assays performed with over 30 different natural and synthetic sialylated and/or sulfated compounds are utilized to define in greater detail specific structural features involved in oligosaccharide-protein binding. Specifically, the critical features required for binding include the exocyclic hydroxylated side chain of the Sia residue and the alpha 2-6 linkage position to the underlying Gal unit. Surprisingly, alterations of the 2-, 3-, and 4-positions of the latter residue have limited effect on the binding. The nature of the residue to which the Gal is attached may affect binding. Bi(alpha 2-6)-sialylated biantennary oligosaccharides are capable of simultaneously interacting with both lectin sites present on the dimeric CD22Rg fusion construct, giving a marked improvement in binding over monosialylated compounds. Furthermore, data are presented indicating that full-length native CD22, expressed on the surface of Chinese hamster ovary cells, is structurally and functionally a multimeric protein, demonstrating a higher apparent affinity for multiply sialylated compounds over monosialylated compounds. These observations provide a mechanism for strong CD22-dependent cell adhesion despite the relatively low Kd for protein-sugar binding.

Structural and functional-group tuning in the design of neuraminidase inhibitors

Analogues of the disaccharide alpha-NeuAc-(2-->6)-beta-D-Gal-OR have been made by modifications at C-1 and C-6 of the galactose and at C-4 of the NeuAc unit, for structure-activity relationship studies with influenza virus neuraminidase. These studies indicate that for the influenza neuraminidase, a larger aglycon at C-1 of galactose is less preferred, whereas the restriction of the rotamer orientation at C-6 of galactose in the "tg" mode favors enzyme binding. Substitution at C-4 of the NeuAc unit has the most profound effect in the influenza neuraminidase hydrolysis and inhibition. For example, azido and acetamido groups at C-4 of the NeuAc units render the sialosides resistant to neuraminidase hydrolysis. However, these derivatives are not inhibitors of the neuraminidase, indicating their lack of binding. On the other hand, a 4-amino substitution of the NeuAc unit not only renders the corresponding sialosides neuraminidase-resistant, but also makes them potent neuraminidase inhibitors. This potent inhibition indicates that the 4-amino groups in these sialosides may engage in favorable interaction with amino acids at the neuraminidase active-site. The conclusion is also supported by docking studies of the carbohydrate structures at the neuraminidase active-site.

Observation of unique cross-linked lattices between multiantennary carbohydrates and soybean lectin. Presence of pseudo-2-fold axes of symmetry in complex type carbohydrates

The tetrameric lectin from Glycine max (soybean) (SBA) has been shown to cross-link and precipitate with N-linked multiantennary complex type oligosaccharides containing nonreducing terminal Gal residues (Bhattacharyya, L., Haraldsson, M., & Brewer, C. F. (1988) Biochemistry 27, 1034-1041). In the present study, negative stain electron micrographs of the precipitates of SBA with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal Gal or GalNAc residues show the presence of highly ordered cross-linked lattices for many of the complexes. The precipitates of SBA with a "bisected" and "nonbisected" N-linked biantennary complex type oligosaccharide containing Gal residues at the nonreducing termini show similar two-dimensional patterns. However, the pattern observed for the precipitates of a tetraantennary complex type oligosaccharide with SBA is distinct from those of the two biantennary carbohydrates. Furthermore, the precipitates formed between the lectin and a synthetic O-linked biantennary ("cluster") glycoside with terminal GalNAc residues show a pattern that is different from those above. Four biantennary pentasaccharide analogs of the blood group I antigen containing beta-LacNAc moieties at the 2,3-, 2,4-, 2,6-, and 3,6-positions of the core Gal also showed ordered patterns in their precipitates with SBA. X-ray crystallographic data and mixed quantitative precipitation profiles of binary mixtures of the four analogs demonstrate that each analog possesses a unique cross-linked lattice with the protein. A common structural feature of the naturally occurring and synthetic carbohydrates that show highly organized cross-linked lattices with SBA is the presence of a pseudo-2-fold axis of symmetry in each oligosaccharide relating the terminal binding epitopes on each arm. This suggests that the symmetry features of certain naturally occurring branch chain oligosaccharides facilitate formation of highly ordered, homogeneous cross-linked complexes with specific lectins.

Observation of unique cross-linked lattices between multiantennary carbohydrates and soybean lectin. Presence of pseudo-2-fold axes of symmetry in complex type carbohydrates

The tetrameric lectin from Glycine max (soybean) (SBA) has been shown to cross-link and precipitate with N-linked multiantennary complex type oligosaccharides containing nonreducing terminal Gal residues (Bhattacharyya, L., Haraldsson, M., & Brewer, C. F. (1988) Biochemistry 27, 1034-1041). In the present study, negative stain electron micrographs of the precipitates of SBA with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal Gal or GalNAc residues show the presence of highly ordered cross-linked lattices for many of the complexes. The precipitates of SBA with a "bisected" and "nonbisected" N-linked biantennary complex type oligosaccharide containing Gal residues at the nonreducing termini show similar two-dimensional patterns. However, the pattern observed for the precipitates of a tetraantennary complex type oligosaccharide with SBA is distinct from those of the two biantennary carbohydrates. Furthermore, the precipitates formed between the lectin and a synthetic O-linked biantennary ("cluster") glycoside with terminal GalNAc residues show a pattern that is different from those above. Four biantennary pentasaccharide analogs of the blood group I antigen containing beta-LacNAc moieties at the 2.3-, 2.4-, 2.6-, and 3.6-positions of the core Gal also showed ordered patterns in their precipitates with SBA. X-ray crystallographic data and mixed quantitative precipitation profiles of binary mixtures of the four analogs demonstrate that each analog possesses a unique cross-linked lattice with the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Myiasis in filarial lymphoedema due to Chrysomyia bezziana

In patients with filarial lymphoedema of the limbs, infestation by maggots is extremely rare. We saw three patients with lymphoedema who harboured Chrysomyia bezziana in leg ulcers and in one of them 128 maggots were recovered. A course of local dressing, antibiotics and anti-inflammatory drugs resulted in healing of the wounds. Ulcers in patients with lymphoedema should be carefully tended with cleaning and dressing otherwise myiasis may supervene.

Comparison of the NPY receptors mediating vasoconstriction of the guinea-pig uterine artery and thoracic vena cava using a range of NPY analogues

The ability of analogues of neuropeptide Y (NPY) to produce direct vasoconstriction, or to antagonize NPY constrictions, was examined in isolated segments of the thoracic vena cava and the uterine artery of guinea-pigs, where NPY mediates a slow phase of sympathetic vasoconstriction. [Leu31,Pro34]NPY, NPY(13-36) and NPY(18-36) all contracted the uterine artery and the vena cava. Contractions produced by [Leu31,Pro34]NPY were similar in time course to those produced by porcine NPY (pNPY), although contractions produced by NPY(13-36) or NPY(18-36) typically were slower than pNPY contractions. In both vessels the order of potency of the agonists was pNPY > or = [Leu31,Pro34]NPY > NPY(13-36) > NPY(18-36). High concentrations (10(-5)mol.l-1) of pNPY or [Leu31,Pro34]NPY produced desensitization of contractions of the uterine artery produced by NPY(13-36). The reported NPY receptor antagonists, PYX-1 and PYX-2 (5 x 10(-6)mol.l-1), slightly reduced (by 21-47%) the magnitude of constrictions produced by exogenous pNPY (1-3 x 10(-8) mol.l-1) in both the uterine artery and the vena cava. These results show that the NPY receptors mediating slow sympathetic vasoconstriction of both the uterine artery and the vena cava are likely to be predominantly Y1 receptors, despite differences between the adrenoceptors mediating sympathetic responses in the two blood vessels.