Megacities as drivers of national outbreaks: The 2017 chikungunya outbreak in Dhaka, Bangladesh.

BACKGROUND: Several large outbreaks of chikungunya have been reported in the Indian Ocean region in the last decade. In 2017, an outbreak occurred in Dhaka, Bangladesh, one of the largest and densest megacities in the world. Population mobility and fluctuations in population density are important drivers of epidemics. Measuring population mobility during outbreaks is challenging but is a particularly important goal in the context of rapidly growing and highly connected cities in low- and middle-income countries, which can act to amplify and spread local epidemics nationally and internationally. METHODS: We first describe the epidemiology of the 2017 chikungunya outbreak in Dhaka and estimate incidence using a mechanistic model of chikungunya transmission parametrized with epidemiological data from a household survey. We combine the modeled dynamics of chikungunya in Dhaka, with mobility estimates derived from mobile phone data for over 4 million subscribers, to understand the role of population mobility on the spatial spread of chikungunya within and outside Dhaka during the 2017 outbreak. RESULTS: We estimate a much higher incidence of chikungunya in Dhaka than suggested by official case counts. Vector abundance, local demographics, and population mobility were associated with spatial heterogeneities in incidence in Dhaka. The peak of the outbreak in Dhaka coincided with the annual Eid holidays, during which large numbers of people traveled from Dhaka to other parts of the country. We show that travel during Eid likely resulted in the spread of the infection to the rest of the country. CONCLUSIONS: Our results highlight the impact of large-scale population movements, for example during holidays, on the spread of infectious diseases. These dynamics are difficult to capture using traditional approaches, and we compare our results to a standard diffusion model, to highlight the value of real-time data from mobile phones for outbreak analysis, forecasting, and surveillance.

Impact of methods for uterine incision closure on repeat caesarean section scar of lower uterine segment.

OBJECTIVE: To compare the effect of different suturing techniques in repeat caesarean section in terms of scar thickness, blood loss, operative time and scar dehiscence at the time of next caesarean section. STUDY DESIGN: A randomized double blinded trial. PLACE AND DURATION OF STUDY: Obstetrics and Gynaecology Department of Bahawal Victoria Hospital, Bahawalpur, from June 2005 to June 2010. METHODOLOGY: Ninety patients undergoing repeat caesarean section were included and randomly assigned to one of the three groups. Group A underwent one layer closure; Group B underwent two layer closure while Group C underwent modified two layer closure of the uterine incision. Ultrasonographic evaluation of the scar thickness was performed at 6 weeks post operatively and longer follow-up was done in next caesarean for scar dehiscence. Frequency percentages were obtained and compared using chi-square test with significance at p < 0.05. RESULTS: In only 2 (6.6%) of modified two layer closure cases, it was necessary to use additional haemostatic sutures, compared with 16 (53%) of one layer closure group, and 10 (33%) of the two layer closure group. At 6 weeks, the mean car thickness in group C (17.08 +1.635 mm) was significantly greater (p < 0.001) as compared to group A (13.19 + 1.32 mm) and group B (14.58 +1.18 mm). At long-term follow-up, only 1 (6%) case from group C showed the "uterine window" at the time of repeat caesarean section as compared to 3 (23%) in group A and 2 (14%) in group B. CONCLUSION: Scar thickness was significantly increased with modified two layer closure when compared with traditional one and two layer closure of lower transverse uterine incision at the time of repeat caesarean section.