Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

Lymphatic filariasis infects 120 million people in 73 countries worldwide and continues to be a worsening problem, especially in Africa and the Indian subcontinent. Elephantiasis, lymphoedema, and genital pathology afflict 44 million men, women and children; another 76 million have parasites in their blood and hidden internal damage to their lymphatic and renal systems. In the past, tools and strategies for the control of the condition were inadequate, but over the last 10 years dramatic research advances have led to new understanding about the severity and impact of the disease, new diagnostic and monitoring tools, and, most importantly, new treatment tools and control strategies. The new strategy aims both at transmission control through community-wide (mass) treatment programmes and at disease control through individual patient management. Annual single-dose co-administration of two drugs (ivermectin + diethylcarbamazine (DEC) or albendazole) reduces blood microfilariae by 99% for a full year; even a single dose of one drug (ivermectin or DEC) administered annually can result in 90% reductions; field studies confirm that such reduction of microfilarial loads and prevalence can interrupt transmission. New approaches to disease control, based on preventing bacterial superinfection, can now halt or even reverse the lymphoedema and elephantiasis sequelae of filarial infection. Recognizing these remarkable technical advances, the successes of recent control programmes, and the biological factors favouring elimination of this infection, the Fiftieth World Health Assembly recently called on WHO and its Member States to establish as a priority the global elimination of lymphatic filariasis as a public health problem.

Strategies and tools for the control/elimination of lymphatic filariasis.

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

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182000066646

Re-assessing the global prevalence and distribution of lymphatic filariasis.

Reports of malaria are increasing in many countries and in areas thought free of the disease. One of the factors contributing to the reemergence of malaria is human migration. People move for a number of reasons, including environmental deterioration, economic necessity, conflicts, and natural disasters. These factors are most likely to affect the poor, many of whom live in or near malarious areas. Identifying and understanding the influence of these population movements can improve prevention measures and malaria control programs.

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Malaria on the move: human population movement and malaria transmission.

Background: Phthalates are ubiquitous environmental contaminants. Because of potential adverse effects on human health, butylbenzyl phthalate [BBzP; metabolite, monobenzyl phthalate (MBzP)], di-n-b...

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Temporal trends in phthalate exposures: findings from the National Health and Nutrition Examination Survey, 2001-2010.

Lymphatic filariasis caused by Wuchereria bancrofti and Brugia malayi is an important public health problem in India. Both parasites produce essentially similar clinical presentations in man, related mainly to the pathology of the lymphatic system. Filariasis is endemic in 17 States and six Union Territories, with about 553 million people at risk of infection. The Government of India has accorded a high priority for elimination of this infection through mass chemotherapy programme (annual, single dose of Diethylcarbamazine citrate, i.e. DEC - 6 mg/kg of bodyweight, plus Albendazole repeated four to six times). This campaign has become a part of the National Vector-Borne Disease Control Programme in 2003 under the National Health Policy 2002 and aims to eliminate filariasis by 2015. We discuss here the epidemiology and current control strategy for filariasis; highlighting key issues, challenges and options in the implementation of the programme, and suggesting measures for mid-course corrections in the elimination strategy.

Lymphatic filariasis in India: Epidemiology and control measures

Context: Arthropod-borne diseases are remaining as a major public health issue in the resource-constrained settings. Mosquitoes are closely associated with mankind since time immemorial and play an important role in the transmission of many dreadful diseases like malaria, filariasis, Japanese encephalitis, dengue and yellow fever. Over the decades, vector control is an important element to minimize the vector-borne disease burden worldwide and in fact, it heavily relies upon synthetic insecticides as a mainstay. However the overuse and misuse of insecticides have led to the emergence of resistance, which undermines the potentiality of vector control. Evidence Acquisition: In order to pursue effective research pertained to this issue, a detailed search on Scopus, Medline, Google Scholar and academic premier databases has been conducted between the time periods of 1955 and 2012. Results: Over the past six decades, insecticides are serving as one of the important arsenals in the fight against vector-borne diseases to save hundreds of millions of lives. Consequently, in the last decade we have attained a remarkable success to combat with many diseases particularly malaria due to the combined effect of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). Currently, malaria mortality rates have drastically fallen by more than 25% globally, 33% in sub-Saharan Africa and over a million lives have been saved attributable to massive scale-up of LLINs and IRS. Since, both LLINs and IRS are cost-effective and robust form of interventions; they are serving as a central pillar in the National Malaria Control Programmes (NMCPs) of malaria endemic countries. Nevertheless, LLINs are easy-to-deliver, most economical and practical even in the resource-poor settings, where implementation of IRS is not feasible. The heavy reliance, recurrent and inappropriate insecticide applications are key sources for resistance which is a potential threat to the global public health. Therefore, it has to be addressed immediately to sustain the recent success of vector control, unless otherwise it would become uncertain. Conclusions: Though, development of resistance is an evolutionary phenomenon, it can be tackled judiciously by implementing appropriate and comprehensive resistance monitoring and management strategies within the framework of integrated vector management. This scrutiny recommends the following measures; (i) identification of effective novel tools for monitoring and evaluation, (ii) searching for alternative interventions to minimize the further resistance evolution as well as to preserve the efficiency of existing insecticides, (iii) exploration of next generation vector control tools in terms of nets and new classes of non-pyrethroid insecticide formulation with new mode of action, (iv) building partnership by bringing together the people actively engaged in the vector control, like public health experts, policy-makers, researchers, medical entomologists and insecticide manufacturers, could ideally pave the way to collectively address the current debacle in the near future.

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Insecticide Resistance in Insect Vectors of Disease with Special Reference to Mosquitoes: A Potential Threat to Global Public Health

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8% suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68% of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

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Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

Background
The Global Programme to Eliminate Lymphatic Filariasis (GPELF) depends upon Mass Drug Administration (MDA) to interrupt transmission. Therefore, delimitation of transmission risk areas is an important step, and hence we attempted to define a geo-environmental risk model (GERM) for determining the areas of potential transmission of lymphatic filariasis.

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Delimitation of lymphatic filariasis transmission risk areas: a geo-environmental approach

Dengue fever is re-emerging as a major scourge in south-east Asian countries, affecting about 50-100 million people and causing about 25,000 deaths annually. The Indian population as a whole is at risk of succumbing to this disease. This study genetically characterized viruses causing dengue infection in Kerala, one of the worst affected states of the country, during the disease outbreaks in 2008-2010. All four serotypes of dengue virus (DENV), DENV-1, DENV-2, DENV-3 and DENV-4, were found to be prevalent in the state. The genotypes recognized for these were III, IV, III and I, respectively. Phylogenetic analysis showed that the re-emergence of serotype DENV-4 reported in Maharashtra and Andhra Pradesh recently is spreading to different regions of the country. The circulation of all four DENV serotypes in Kerala may lead to an increase in the prevalence of more severe complications of this emerging disease, such as dengue haemorrhagic fever and dengue shock syndrome.

S. Sabesan

Papers

Lymphatic filariasis in India: Epidemiology and control measures

Insecticide Resistance in Insect Vectors of Disease with Special Reference to Mosquitoes: A Potential Threat to Global Public Health

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

Delimitation of lymphatic filariasis transmission risk areas: a geo-environmental approach

Genetic characterization of dengue viruses prevalent in Kerala State, India.