Rina Tilak

A laboratory investigation into oviposition responses of Aedes aegypti to some common household substances and water from conspecific larvae

BACKGROUND The surveillance of Dengue vector - Aedes aegypti, is routinely done by using ovitraps (a dark container filled with water and a wooden paddle/towel cloth provided as a oviposition substrate), which indicates the extent of Aedes activity in an area. METHOD The study evaluated the oviposition responses of laboratory bred gravid Aedes aegypti to commonly available household substances by use of ovitrap method. RESULTS Oviposition avoidance or deterrence was exhibited by gravid Aedes to ovitraps baited with salt, fenugreek, vinegar, lime juice, hibiscus leaves, radish and curry leaves, whereas positive oviposition response was noticed to waters from conspecific (of the same species) larvae and cumin seeds baited ovitraps. CONCLUSION The study findings may be utilized by researchers for further chemical analysis of the active ingredients of the substances found promising with a view to explore the possibility of their use by community and individuals for Aedes surveillance and control.

Emergence of Schoengastiella ligula as the Vector of Scrub Typhus Outbreak in Darjeeling: Has Leptotrombidium deliense Been Replaced?

BACKGROUND Following a suspected outbreak of scrub typhus in Kurseong, Darjeeling, the Armed Forces Medical College, Pune was requested by the National Institute of Epidemiology and the State authorities to undertake investigation of the ongoing scrub typhus outbreak and suggest containment measures. MATERIALS AND METHODS The epidemic team undertook clinical, entomological and serological studies to understand the local disease pattern and delineate high risk areas, host diversity by rodent trapping using Sherman traps, mite fauna diversity, abundance and vector species identification by phase contrast microscopy for preparation of electronic database and rodent and human serological studies by Weil Felix and PCR. RESULTS The results indicate no association of scrub typhus with age and sex (P=0.37 and 0.74 respectively). The maximum cases occurred amongst the tea garden workers (73%) in the age group of 25-44 years. The predominant clinical presentation was fever (100%) with headache (75%), lymphadenopathy (45%) and presence of eschar (76.7%). The dominant host species (50% of trapped rodents) was shrew Suncus murinus, the index animal for scrub typhus, which contributed maximally to the vector abundance (52.96%) with a chigger index of 61.56. The trombiculid mite Schoengastiella ligula was the vector species much against the expected mite vector Leptotrombidium deliense, in the area. The study found the presence and abundance of vector species which corroborated well with the occurrence of cases in the various localities within the subdivisions. CONCLUSION The study thus establishes Schoengastiella ligula as the vector of scrub typhus outbreak in Kurseong, Darjeeling. Preventive and containment measures with emphasis on reduction of man - vector contact were suggested to the state authorities to contain the outbreak.

Vector Databank in the Indian Armed Forces

BACKGROUND Medical intelligence of disease vectors deals with understanding vector distribution and control. METHODS An entomological baseline survey using standard vector sampling techniques was done as a pilot study to map the vectors of defence importance in two cantonments of Pune with a view to establish a vector databank and impart training to armed forces personnel in vector surveillance. RESULT The project trained 142 armed forces personnel in surveillance techniques in three years. Seventeen species of mosquitoes comprising of eight vector species were collected. Three other vectors viz. Rhipicephalus sanguineus, Xenopsylla cheopis and Leptotrombidium deliense are reported. CONCLUSION The study emphasizes the need for vector mapping /surveillance in each area for preventing morbidity and mortality amongst troops. It also focuses on indigenous fabrication of vector sampling tools and training of personnel for capacity building which in turn will enable such surveys to be undertaken in other units and deployment areas.

Mass scabies management in an orphanage of rural community: An experience

Scabies is an important health problem characterized by continuous transmission throughout the year. It is ubiquitous, contagious, and debilitating parasitic dermatoses, known since antiquity and having widespread distribution in the tropics. The worldwide prevalence has been estimated at about 300 million cases yearly, although it may be an overestimate.1 Scabies occurs in both sexes, at all ages, in all ethnic groups, and at all socioeconomic levels. In India, the incidence ranges from 13% to 59% in rural2 and urban areas.3 Scabies is a Latin word that simply means to scratch and is caused by the mite Sarcoptes scabiei var-hominis, and is usually associated with conditions of overcrowding, low socioeconomic standards, low level of education and poor hygiene.4 Overcrowding and sexual contacts are the most common, but not exclusive modes of transmission. The mite of scabies burrows into the outer layer of the skin (stratum corneum) and feeds on skin cells and fluids. It is this feeding action, and its products (digestive secretions and feces) that provoke an immune reaction from the body which results in itching and other symptoms of scabies. Scabies causes considerable discomfort and can result in severe secondary complications such as impetigo, cellulitis, pyoderma, bacteraemia and post-streptococcal glomerulonephritis.5–7 The study was undertaken in the Rural Health Training Centre of a medical college located at Kasurdi village, in Pune district of Maharashtra. During routine visits, three school going children of a nearby orphanage reported with the clinical symptoms suggestive of Scabies i.e. insomnia due to severe itching at night, rashes, irritability leading to school absenteeism and poor quality of life. On examination, the children were found to be having scabies. Scabies in orphanages are not uncommon but unfortunately are hard to treat because of reasons like delayed diagnosis, inadequate treatment, malnutrition, associated allergic and bacterial infections and inadequate follow-up.8 It was thus decided that all the children at the orphanage be examined and an intervention to cure all children of the orphanage be undertaken. The study thus aimed to assess the prevalence of Scabies in an orphanage in a rural village of Maharashtra State and to conduct a mass Scabies treatment and follow-up of all children and care givers. The study in addition also provided health education and trained the care givers for timely management of scabies in the setup.

Zoonotic surveillance for rickettsiae in rodents and mapping of vectors of rickettsial diseases in India: A multi-centric study

Background: The global resurgence of rickettsial diseases and their potential to impact the fitness of military personnel and inflict widespread casualties amongst civil populations has emerged as a major cause of public health concern. Absence of surveillance system, lack of awareness amongst medical fraternity to rickettsial activity along with the difficulty in diagnosis because of their protean clinical manifestations are reasons for the outbreaks of these diseases. Objectives: To determine rickettsial activity amongst rodents and study vector diversity, abundance and their distribution to enable mapping of rickettsial hotspots. Methods: Zoonotic surveillance was undertaken in six selected study areas in India - Jammu, Akhnoor, Rajouri-Poonch, Udhampur-Nagrota, Dehradun and Pune. Weil–Felix test was used for rickettsial sero-surveillance amongst rodents and standard identification keys were used for mapping vector diversity and database preparation. Results: Serological findings revealed positivity to all the three rickettsial antigens (OXK, OX19 and OX2) in Jammu, OX19 in Dehradun and OXK and OX2 positivity in Udhampur-Nagrota belt. The vector database records presence of 16 species of trombiculid mites from three important genera - Leptotrombidium, Schoengastiella and Gahrliepia with ticks from five genera and 8 species of fleas from four genera. Mite fauna of study sites has been enriched with addition of new records of mite species (five mite species at Pune, two at Akhnoor with one mite species each at Jammu and Dehradun). Conclusion: The study reveals rickettsial activity amongst rodents at Jammu, Dehradun and Udhampur-Nagrota belt. The results correlate well with the presence of vectors of scrub and tick typhus and corroborate the occurrence of outbreaks of these diseases in the respective areas.

A new ‘Hydration Protocol’ for Prevention and Management of Heat Stroke in High Endurance Military Training

Background: Rigorous exercise is a hallmark of military training and more than often gives rise to dehydration and stress related injuries. Proper hydration and carbohydrate loading can overcome dehydration and protein supplement can prevent its imminent complications. Severe dehydration gives rise to loss of fluid, electrolyte imbalance and acid base disorders and needs to be managed with correct fluids, quantitatively and qualitatively. Objectives. To develop and implement a new hydration protocolfor military endurance training in hot and humid climatic conditions. Methodology: A longitudinal pilot study was conducted amongst the under trainees in a military academy in Southern India which has a hot and humid climate throughout the year. Data was collected for all heat exhaustion and heat stroke cases admitted to the hospital A new hydration and diet protocol based on extensive review of existing and current literature was developed The protocol was divided into three parts Le. pre exercise, during exercise and post exercise. Results: Out of a total of 1200 under trainees being trained in each term of six months (both in 2014 and 2015), there were a total of 95 cases of heat exhaustion and 05 cases of heat stroke in 2014 and 48 cases of heat exhaustion and 05 cases of heat stroke in 2015. Conclusion: The results of implementation of the new protocol for endurance training is encouraging with a sharp decline in number of cases of heat exhaustion in 2015 post introduction of the new hydration and dietprotocol An appropriate selection of food andfluid, timing of intake, and supplement choices as per the new hydration protocol we developedfor the study are highly recommended for optimal health and exercise performance in military training and to prevent heat related illnesses.

Surveillance of Scrub Typhus in the fringe areas around Pune : Potential for Transmission does exist

A field based epidemiological study was undertaken to assess the potential of transmission of scrub typhus in the sylvatic and transitional (fringe) areas at ten different locations around Pune. Parameters studied included rodent trapping and identification, entomological parameters, immunological studies on rodent sera, and rodent organ impression smears. The study revealed that Rattus r rufescence, Rattus meltada, Suncus murinus and Rattus blanfordi were the predominant sylvatic rodent species. All the species showed mild to moderate infestation with trombiculid mite larvae, with Rr rufescence and S murinus showing even higher levels of infestation. Pooled rodent sera showed mild rise of OX2 in 13.9%, OX19 in 5.6% and OXK in 9.8% of the pooled sera. The rise in titres was appreciable among rodents from Lonavala, Khadakvasla, Panchet, Singhgadh and Kondhwa areas. Based on the findings of the study, certain recommendations on prevention, surveillance and epidemic investigations of scrub typhus in the Armed Forces have been submitted.