Scrub typhus is the oldest known vector-borne zoonotic infectious disease in the world which is life-threatening for all age groups as it presents acute febrile illness along with multi-organ involvements and spread with the biting of infectious ‘Trombiculid mite’ (chigger mite). The pathogen of this disease is an obligatory coccobacillus gram-negative rickettsial bacteria Orientia tsutsugamushi. Scrub typhus disease was previously confined geographically only to the Asia Pacific region (tsutsugamushi triangle), but in recent years it has crossed its limit and has spread in other countries beyond the tsutsugamushi triangle and has become more hazardous for the community. The objective of this study is to explore the scrub typhus disease outbreak trends with existing information in southern Rajasthan state, India. This study concluded that scrub typhus disease is being re-emerged again and again in various Indian geographical regions with new species of vectors. The disease has been raised in tremendous amounts in Rajasthan within the last five years especially in the hilly zone and has led to major public health problems with other zoonotic diseases.

Japanese encephalitis (JE) is a very serious public health problem in India and the conducive environment permit its emergence in non-endemic areas in the country. There are constant changes taking place in the pattern of current agricultural practices and vector breeding habitats which had far-reaching consequences on the epidemiology of JE and the severity of epidemic outbreaks today. Due to the continuous ecological changes taking place, vectors changed in their breeding dynamics, feeding, and resting behavior and started invading previously non-endemic areas. JE has recently spread to new territories due to land-use changes, including forest fragmentation and concentrated livestock production. Changes in the livestock population decreased the cattle pig ratio which enhanced the Japanese encephalitis virus (JEV) infection. This review brings forth the present widespread changes encountered that grossly impact the risk of infection in many places for the emergence of Japanese encephalitis and to address the implications for its control.

Background & objectives: Recently, the use of biodegradable and environment friendly plant-based bioinsecticides has received a great deal of attention from researchers to control insect disease vectors. The aim of this research is to determine the larvicidal efficacy of Ruta graveolens essential oil against third instar larvae of two species of mosquito (Culex pipiens and Culiseta longiareolata) and a biological model Drosophila melanogaster. Methods: Culiseta longiareolata and Culex pipiens larvae were collected from untreated areas located in Tebessa and Drosophila melanogaster, the wild strain collected from rotten apples in the Tebessa region. Ruta graveolens essential oil has been tested at different concentrations between 2.5μ/mL and 140μL/mL against third instar larvae of the three species under standard laboratory conditions according to the recommendations from the Word Health Organization. The effects were examined on mortality, growth and the main components (proteins, carbohydrates, lipids). Results: The essential oil showed larvicidal activity with LC₅₀ and LC₉₀ values (10.85μL/mL, 70.95μL/mL and 39.4μL/mL), (26μL/mL, 144.5μL/mL and 89.57μL/mL) against third instar larvae of Drosophila melanogaster, Culex pipiens and Culiseta longiareolata respectively. In addition, it disrupted the growth and several morphological malformations were observed. It also affected growth and the main components (proteins, carbohydrates, lipids). Interpretation & conclusion: The essential oil affected growth and energy reserves for all three species. The results indicated that the essential oil of Ruta graveolens has good potential as a source of natural larvicides.

Background & objectives: The emergence and re-emergence of arboviruses such as dengue, Chikungunya and Zika viruses causing morbidity and mortality around the globe are of serious concern. A safe and effective vaccine is essential to control viral transmission. The salivary proteins of the mosquito that aid in blood probing, feeding and development are immunogenic. We aimed to report a multi-epitope candidate vaccine chimera from Aedes aegyptii mosquito salivary proteins OBP 22 and OBP 10 that could confer protection against all pathogens transmitted by the vector. Methods: Linear and conformation B-cell epitopes and MHC class-I and class-II binding T- cell epitopes were predicted using bioinformatic tools. Selected B- and T-cell epitopes were chosen for designing a multiepitope vaccine construct. The chimeric construct was analyzed for its immunogenicity, TAP and proteasomal cleavage, allergenicity, and structural validation for its suitability to be used as a candidate vaccine. Molecular docking was carried out to analyze the binding interactions with TLRs molecules. Results: A chimeric multiepitope vaccine was designed with the best-selected combination of immunogenic B-cell epitope, cytotoxic and helper T-cell and gamma interferon inducing epitopes with suitable adjuvant and linkers. The interacting residues between the candidate vaccine and the TLR molecules have been identified. Interpretation & conclusion: The proposed multiepitope candidate vaccine was designed from the mosquito salivary protein OBP 22 and OBP 10. The candidate vaccine was found promising for the protection against arboviruses. Further clinical validation is warranted to prove its efficacy, safety and immunogenicity for its potential use.

Background & objectives: Robust forecasting of malaria cases is desirable as we are approaching towards malaria elimination in India. Methods enabling robust forecasting and timely case detection in unstable transmission areas are the need of the hour. Methods: Forecasting efficacy of the eight most prominent statistical models that are based on three statistical methods: Generalized linear model (Model A and Model B), Smoothing method (Model C), and SARIMA (Model D to model H) were compared using last twelve years (2008–19) monthly malaria data of two districts (Kheda and Anand) of Gujarat state of India. Results: The SARIMA Model F was found the most appropriate when forecasted for 2017 and 2018 using model-building data sets 1 and 2, respectively, for both the districts: Kheda and Anand. Model H followed by model C were the two models found appropriate in terms of point estimates for 2019. Still, we regretted these two because confidence intervals from these models are wider that they do not have any forecasting utility. Model F is the third one in terms of point prediction but gives a relatively better confidence interval. Therefore, model F was considered the most appropriate for the year 2019 for both districts. Interpretation & conclusion: Model F was found relatively more appropriate than others and can be used to forecast malaria cases in both districts.

Background & objectives: Scrub typhus or chigger borne typhus, caused by Orientia tsutsugamushi is an emerging vector-borne disease as large numbers of cases have been reported in various tropical countries. It is transmitted to humans through bites of infected chiggers (larval mites). The knowledge about the vector, its distribution, density and habitat are important so as to understand the epidemiology of scrub typhus in a given area. To control rickettsial infections, regular rodent-vector surveillance should be planned in areas where the disease transmission is occurring and it will also help to strengthen the existing entomological data related to the vector of scrub typhus in northern India. Methods: In the present study, rodent-vector surveillance was planned for one whole year, covering both mite active and non-active seasons (October 2019-December 2020) in selected areas of Chandigarh and Punjab in north India. Rodent tissues and mites were also examined for the presence of O. tsutsugamushi by nested PCR for 56 kDa gene and real-time PCR for 47 kDa outer membrane protein gene. 18S gene PCR was performed for molecular identification of mites. Results: In the surveillance, three types of ectoparasite, viz. mites, fleas and ticks were obtained in rodents. All mites found were of Laelapidae family. None of the pooled rodent tissue samples as well as mite samples were found positive for O. tsutsugamushi by nested PCR for rickettsial DNA. Interpretation & conclusion: In the present study, we did not get any evidence of carriage of O. tsutsugamushi in either mites or rodents collected and sampled in selected regions in Chandigarh and Punjab. We need to strengthen the entomological surveillance over a broader region and increase the frequency of trapping rodents to increase clarity on vector-reservoir dynamics in this geographical region.

Background & objectives: Japanese encephalitis (JE) is a major public health problem in India. The first outbreaks of JE have been reported from the North-eastern regions of Assam, particularly from the Lakhimpur district of Assam between July–August 1989. In Assam every year many people died due to JE. This study was performed to investigate the molecular epidemiology of JE in pigs in Lakhimpur district of Assam and the risk factors associated with causing Japanese encephalitis in pigs. This study will help to map out the endemic regions and to know where and when to apply the most control strategies towards the prevention and control of the disease. Methods: A total of 342 serum samples from pigs were collected from 10 organized and 20 unorganized farms from 9 blocks and recorded to age, sex and breed and tested by RT-PCR. Pig farms and the surrounding environment were studied for assessment of farm-level risk factors responsible for JEV infection in pigs. Results: Out of 342 samples tested for detection of the E gene of JEV, 14 samples were found to be positive with a prevalence rate of 4.09%. Age, sex and breed-wise higher cases were found in at the age group above 12 months, sex wise female and breed-wise local pigs. Pig farms less than 500 meters from risk factors like rice field, stagnant water source, wild bird exposure to farm and mosquito exposure at farm/ bite to pigs, found to be more numbers of JE cases. Interpretation & conclusion: Molecular epidemiology of JE in pigs, and humans; positive at Lakhimpur recommend the need for uninterrupted surveillance of this virus in pigs specially those areas where pig population is more and all risk factors are present.

Background and objectives: In America, of the 44 species of Anopheles, nine are main vectors of malaria and, of these, genetic information exists for seven. Hence, this study sought to know the gene flow and diversity of the seven principal vectors of malaria at the Americas level. Methods: For the seven species and the sequences of the mitochondrial cytochrome c oxidase I (COI) gene obtained from the GenBank and Bold System, genetic analyzes of populations and genetic structure were performed and haplotype networks and phylogenetic trees were obtained. Results: For the seven species, 1440 sequences were analyzed and 519 haplotypes were detected. The Hd and π values were higher within a continental context than by countries. Neutrality tests indicated positive and negative values with most of these being significant (p < 0.05). Phylogenetic analyses for all the species recovered three clades with no geographic pattern among them. Interpretation & conclusion: Studies suggest that native species of Anopheles from the Americas have greater haplotype diversity and low genetic differentiation due to the lack of physical barriers to impede gene flow among these populations. Moreover, all the species are interconnected by roadways. This scenario complicates the epidemiological picture of malaria in the Americas.

India’s target of malaria elimination by 2030 may not be achieved solely by detecting Plasmodium falciparum and P. vivax, the two common Plasmodium species causing infections in humans. Sporadic reports have been documented on other Plasmodium species in the country, associated mostly with travel history. A febrile patient of Indian origin (Non-resident Indian (NRI)) was diagnosed with an infection of Plasmodium ovale curtisi malaria on his arrival from Sudan. A case report from Kerala was published in December 2020 and this is second report. Due to the inaccessibility of molecular techniques for routine diagnosis, this neglected non-falciparum malaria goes undetected. For an accurate diagnosis, suspected malaria cases should be tested using PCR and other advanced methods.

Background & objectives: Scrub typhus is a neglected tropical disease common in Asia and Africa. It usually presents with non-specific symptoms like fever, rashes, and lymphadenopathy. It has a varying range of clinical picture that often leads to misdiagnosis and initiation of non-specific treatment. This disease is thus associated with high morbidity and mortality. We aim to highlight the uncommon presentations of this common disease to create awareness regarding the unusual presentations of scrub typhus. Methods: This prospective study was performed over a period of two months enrolling eleven adult patients with serological evidence of anti-scrub typhus IgM antibodies. Results: All enrolled 11 cases [5 males (45.5%) and 6 females (54.5%)] were positive for anti-ST IgM antibodies and negative for other tested microbial agents. 7/11 (63.6%) patients were admitted with a clinical diagnosis of acute encephalitis syndrome (AES as per standard WHO definition), 3/11 (27.3%) patients presented with jaundice and 1/11 (9.1%) patients presented with rashes. Two out of 7 (28.6%) AES cases had developed peripheral gangrene of extremities. Interpretation & conclusion: Scrub typhus is a common tropical disease that can have various unusual clinical presentations like meningoencephalitis, vasculitis, acute kidney injury, jaundice, MODS. It closely mimics other infective etiologies making its diagnosis difficult. A high index of suspicion and clinical awareness is required in clinical practice to identify the different presentations of this disease so that early treatment can be initiated to reduce morbidity and mortality associated with this disease.