Mass gathering events are associated with major public health challenges. The 2014 Lancet Series on the new discipline of mass gatherings medicine was launched at the World Health Assembly of Ministers of Health in Geneva in May, 2014. The Series covered the planning and surveillance systems used to monitor public health risks, public health threats, and experiences of health-care providers from mass gathering events in 2012 and 2013. This follow-up Review focuses on the main public health issues arising from planned mass gathering events held between 2013 and 2018. We highlight public health and research data on transmission of infectious diseases and antibioticresistant bacteria, mass casualty incidents, and non-communicable diseases, including thermal disorders. In the events discussed in this Review, the combination of a large influx of people, many from countries with outbreakprone infectious diseases, with a high degree of crowd interactions imposed substantial burdens on host countries' health systems. The detection and transmission of antibiotic-resistant bacteria in pilgrims attending the Kumbh Mela and the Hajj raise concern of possible globalisation from mass-gathering religious events. Priorities for further investments and opportunities for research into prevention, surveillance, and management of these public health issues are discussed. Search strategy and selection criteriaWe searched PubMed, Embase, Cochrane Library, and Google Scholar for English language papers that were published from a.zumla@ucl.ac.uk disorders. Priorities for further investments and oppor tunities for research into prevention, surveillance, and management of communicable and noncom municable diseases, thermal disorders, and mass casualty incidents are discussed.

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is causing a severe global health emergency owing to its highly infectious nature. Although the symptoms of SARS-CoV-2 are well known but its impact on nasopharyngeal microbiome is poorly studied. The present cross-sectional study was intended to understand the perturbation in the nasopharyngeal microbiome composition within the infected (n=63) and non-infected (n=26) individuals using 16S rRNA gene based targeted amplicon sequencing and their association with host types and the prevalence of opportunistic pathogens at the stage of infection. The results confirmed that number of OTUs were significantly (p < 0.05) decreased in the SARS-CoV-2 infected individuals in comparison to non-infected individuals. Pairwise Wilcoxon test showed a significant (p<0.05) increase in the abundance of Proteobacteria in infected individuals compared to non-infected ones and vice-versa for Fusobacteria and Bacteroidetes. Similarity percentage (SIMPER) analysis showed the increment in the abundance of opportunistic pathogens ( Haemophilus , Stenotrophomonas , Acineobacter , Moraxella , Corynebacterium I , Gemella , Ralstonia , and Pseudomonas ) involved in secondary infection. Furthermore, this study highlighted the microbial community structure of individuals within and across the families. Further, we also assessed the microbiome associated with host types (age and genders) and COVID-19 conditions (symptomatic and asymptomatic). The data suggested that the host types/conditions during the COVID-19 infection are potential factors in enrichment of specific bacterial communities in upper respiratory tract.

Marcha, thiat, dawdim, hamei, humao, khekhrii, chowan, and phut are traditionally prepared dried starters used for production of various ethnic alcoholic beverages in North East states of India. The surveillance of mycobiome associated with these starters have been revealed by culture-dependent methods using phenotypic and molecular tools. We identified Wickerhamomyces anomalus, Pichia anomala, Saccharomycopsis fibuligera, Pichia terricola, Pichia kudriavzevii, and Candida glabrata by ITS-PCR. The diversity of yeasts and molds in all 40 samples was also investigated by culture-independent method using PCR-DGGE analysis. The average distributions of yeasts showed Saccharomyces cerevisiae (16.5%), Saccharomycopsis fibuligera (15.3%), Wickerhamomyces anomalus (11.3%), S. malanga (11.7%), Kluyveromyces marxianus (5.3%), Meyerozyma sp. (2.7%), Candida glabrata (2.7%), and many strains below 2%. About 12 strains of molds were also identified based on PCR-DGGE analysis which included Aspergillus penicillioides (5.0%), Rhizopus oryzae (3.3%), and sub-phylum: Mucoromycotina (2.1%). Different techniques used in this paper revealed the diversity and differences of mycobiome species in starter cultures of India which may be referred as baseline data for further research.

Marcha and thiat are traditionally prepared amylolytic starters use for production of various ethnic alcoholic beverages in Sikkim and Meghalaya states in India. In the present study we have tried to investigate the bacterial and fungal community composition of marcha and thiat by using high throughput sequencing. Characterization of bacterial community depicts phylum Proteobacteria is the most dominant in both marcha (91.4%) and thiat (53.8%), followed by Firmicutes, and Actinobacteria. Estimates of fungal community composition showed Ascomycota as the dominant phylum. Presence of Zygomycota in marcha distinguishes it from the thiat. The results of NGS analysis revealed dominance of yeasts in marcha whereas molds out numbers in case of thiat. This is the first report on microbial communities of traditionally prepared amylolytic starters of India using high throughput sequencing.

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Significant morbidity and potential mortality following dengue virus infection is a re-emerging global health problem. Due to the limited effectiveness of current disease control methods, mosquito biologists have been searching for new methods of controlling dengue transmission. While much effort has concentrated on determining genetic aspects to vector competence, paratransgenetic approaches could also uncover novel vector control strategies. The interactions of mosquito midgut microflora and pathogens may play significant roles in vector biology. However, little work has been done to see how the microbiome influences the host's fitness and ultimately vector competence. Here we investigated the effects of the midgut microbial environment and dengue infection on several fitness characteristics among three strains of the primary dengue virus vector mosquito Aedes aegypti. This included comparisons of dengue infection rates of females with and without their normal midgut flora. According to our findings, few effects on fitness characteristics were evident following microbial clearance or with dengue virus infection. Adult survivorship significantly varied due to strain and in one strain varied due to antibiotic treatment. Fecundity varied in one strain due to microbial clearance by antibiotics but no variation was observed in fertility due to either treatment. We show here that fitness characteristics of Ae. aegypti vary largely between strains, including varying response to microflora presence or absence, but did not vary in response to dengue virus infection.

Kumbh Mela is one of the largest religious mass gathering events (MGE) involving bathing in rivers. The exponential rise in the number of devotees, from around 0.4 million in 1903 to 120 million in 2013, bathing in small specified sites can have a dramatic impact on the river ecosystem. Here, we present the spatiotemporal profiling of bacterial communities in Godavari River, Nashik, India, comprising five sites during the Kumbh Mela, held in 2015. Assessment of environmental parameters indicated deterioration of water quality. Targeted amplicon sequencing demonstrates approximately 37.5% loss in microbial diversity because of anthropogenic activity during MGE. A significant decrease in phyla viz. Actinobacteria, Chloroflexi, Proteobacteria, and Bacteroidetes was observed, while we noted substantial increase in prevalence of the phylum Firmicutes (94.6%) during MGE. qPCR estimations suggested nearly 130-fold increase in bacterial load during the event. Bayesian mixing model accounted the source of enormous incorporation of bacterial load of human origin. Further, metagenomic imputations depicted increase in virulence and antibiotic resistance genes during the MGE. These observations suggest the striking impact of the mass bathing on river ecosystem. The subsequent increase in infectious diseases and drug-resistant microbes pose a critical public health concern.