Background Vitamin-D deficiency is linked to a wide range of chronic and infectious diseases. Body of literature suggested that the prevalence of this deficiency can have geographical variation. Although vitamin D deficiency is frequently reported in the South Asian population, the scarcity of systematic reviews and meta-analysis means the true extent of the disease and the underlying factors causing it are poorly characterized. Methods A systematic search was performed using two databases (PubMed and Scopus) and one search engine (Google Scholar) for original studies on the South Asian population (published from January 1, 2001, to December 31, 2019). Following the search, a random effect meta-analysis was performed to calculate population-level weighted average, the pooled prevalence of deficiency, and heterogeneity of vitamin D among different countries and genders; in addition to South Asia as a whole. Results Our study, based on our selection criteria was narrowed down to a total of 44,717 participants; which spanned over 65 studies from five South Asian countries. Overall, the pooled prevalence of deficiency was 68% [95% CI: 64 to 72%] with significant heterogeneity (I2 = 98%; p = 0.00). The average level of vitamin D ranged from 4.7 to 32 ng/mL, with a weighted mean of 19.15 ng/mL (weighted standard deviation 11.59 ng/mL). The highest prevalence of vitamin D deficiency was found in Pakistan (73%;95% CI: 63 to 83%) followed by Bangladesh (67%; 95% CI: 50 to 83%), India (67%; 95% CI: 61 to 73%), Nepal (57%; 95% CI: 53 to 60%) and Sri Lanka (48%; 95% CI: 41 to 55%), respectively. This finding indicated a high degree of heterogeneity among the population. (I2 = 98.76%), Furthermore, a gender-wise analysis suggested that in South Asia, the prevalence of vitamin D deficiency was higher in females than males. Conclusion Our findings reveal highly prevalent and variable vitamin D deficiency among the adults of different South Asian countries. Findings from this review would be helpful to generate hypotheses and explore the factors affecting the inter-country variability, alongside strengthening evidence for governments to prioritize mitigation strategies in this region.

Background: Thalassaemia is a potentially life-threatening yet preventable inherited hemoglobin disorder. Understanding local socio-cultural context and level of public awareness about thalassaemia is pivotal for selecting effective prevention strategies. This study attempted to assess knowledge and perceptions about thalassaemia among college students in Bangladesh. Methods: A supervised cross-sectional survey was conducted on 1578 college students using a self-administered structured questionnaire. The survey took place from 15 February 2018 to 17 March 2018 in the Jamalpur district in Bangladesh. Besides the attitude-related questions, the study asked a total of 12 knowledge-related questions, which were scored on a scale of 0-12 points. Results: Over two-thirds (67%) of the college students had never heard of thalassaemia. The urban-rural dichotomy was observed among those familiar with the term; (46.4% from urban vs. 25.8% from rural colleges). A similar pattern was observed for knowledge score; 5.07 ± 1.87 for students from the urban colleges compared to 3.69 ± 2.23 for rural colleges. Students from the science background had the highest knowledge score (5.03 ± 1.85), while those from arts and humanities background scored lowest (3.66 ± 2.3). Nearly 40% of the students were not sure or did not want to be a friend of a thalassaemia patient. Whereas 39% either declined or remained hesitant about helping thalassaemia patients by donating blood. However, most of the respondents (88%) showed a positive attitude towards 'premarital' screening to prevent thalassaemia. Conclusions: This study has identified critical knowledge gaps and societal misperceptions about thalassaemia. A better understanding of these aspects will be pivotal for disseminating thalassaemia related information. As the first study of this kind in Bangladesh, findings from this study has generated baseline data that would contribute to developing effective intervention strategies in Bangladesh and other countries with a comparable socio-cultural setting.

Dengue is a mosquito-borne viral disease commonly reported in the tropical regions of the world. The presence of two mosquito vectors (Aedes aegypti is highly urban, while A. albopictus is less urban) throughout the year makes dengue fever an endemic disease in a number of countries. Among the predicting variables, a rise of temperature and rainfall have shown to be associated with the number of dengue cases [1]. While relatively less emphasized compared to the climatic factors, mass movement is particularly important during large-scale outbreaks. This article presents a case based on the available data from the 2019 outbreak in Bangladesh, where the dengue fever was initially concentrated in Dhaka, the capital city. Dhaka is one of the most crowded megacities in the world, with over 19 million people distributed over 453 square km (spatial density of 41,000/square km) [2]. It is a hub of all key administrative, educational, and industrial activities in Bangladesh. Hence, a considerable proportion of the Bangladeshi population prefers to live in the city for better income, quality education, and better facilities overall. The 2019 dengue outbreak in Dhaka was the most intense since the emergence of dengue outbreaks in late the 1990s in Bangladesh [3]. According to Directorate General of Health Services (DGHS), Bangladesh, a total of 100,201 confirmed dengue cases were admitted in hospitals between January and December 2019; 51,179 cases were reported in Dhaka city and 49,022 across the rest of Bangladesh [4]. This implies a 10-fold increase in hospitalized cases compared with the largest outbreak before 2019. Since the first major outbreak in 2000, all four serotypes (DEN-1-4) were reported in Dhaka city until 2003, a with higher prevalence of DEN-3 serotype. After a hiatus (2013-2016), DEN-3 serotype re-emerged in 2017, and this serotype has been reported to be the most frequently identified during the 2019 outbreak [5,6]. Anecdotal evidence from medical practitioners suggests that dengue patients manifested with a spectrum of atypical symptoms in the 2019 outbreak, which can be related to serodiversity of the viral strains. A recently published nationwide seroprevalence study (2014-2015) showed that 24% of participants had past history of dengue infection in Bangladesh [7]. Seropositivity of the infected individuals was largely confined to three big cities, namely Dhaka, Chittagong, and Khulna, indicating that circulation of dengue virus was not high in the semi-urban and rural areas of Bangladesh [7]. Notably, all major dengue outbreaks in Bangladesh showed a tendency to remain confined mostly in Dhaka city [7], and the 2019 outbreak showed the same trend PLOS NEGLECTED TROPICAL DISEASES