Uncertainty and sensitivity analysis of the basic reproduction number of diphtheria: a case study of a Rohingya refugee camp in Bangladesh, November-December 2017

Ryota Matsuyama; Andrei R Akhmetzhanov; Akira Endo; Hyojung Lee; Takayuki Yamaguchi; Shinya Tsuzuki; Hiroshi Nishiura

doi:10.7717/peerj.4583

Uncertainty and sensitivity analysis of the basic reproduction number of diphtheria: a case study of a Rohingya refugee camp in Bangladesh, November-December 2017

PeerJ. 2018 Apr 2:6:e4583. doi: 10.7717/peerj.4583. eCollection 2018.

Authors

Ryota Matsuyama^{1

2}, Andrei R Akhmetzhanov^{1

2}, Akira Endo^{1

3}, Hyojung Lee^{1

2}, Takayuki Yamaguchi^{1

2}, Shinya Tsuzuki^{1

2}, Hiroshi Nishiura^{1

2}

Affiliations

¹ Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
² Japan Science and Technology Agency, Core Research for Evolutional Science and Technology, Saitama, Japan.
³ London School of Hygiene & Tropical Medicine, University of London, London, UK.

Abstract

Background: A Rohingya refugee camp in Cox's Bazar, Bangladesh experienced a large-scale diphtheria epidemic in 2017. The background information of previously immune fraction among refugees cannot be explicitly estimated, and thus we conducted an uncertainty analysis of the basic reproduction number, R₀.

Methods: A renewal process model was devised to estimate the R₀ and ascertainment rate of cases, and loss of susceptible individuals was modeled as one minus the sum of initially immune fraction and the fraction naturally infected during the epidemic. To account for the uncertainty of initially immune fraction, we employed a Latin Hypercube sampling (LHS) method.

Results: R₀ ranged from 4.7 to 14.8 with the median estimate at 7.2. R₀ was positively correlated with ascertainment rates. Sensitivity analysis indicated that R₀ would become smaller with greater variance of the generation time.

Discussion: Estimated R₀ was broadly consistent with published estimate from endemic data, indicating that the vaccination coverage of 86% has to be satisfied to prevent the epidemic by means of mass vaccination. LHS was particularly useful in the setting of a refugee camp in which the background health status is poorly quantified.

Keywords: Bangladesh; Basic reproduction number; Corynebacterium diphtheriae; Diphtheria; Epidemiology; Mathematical model; Outbreak; Refugee; Statistical estimation; Vaccination.

Grants and funding

The present study was financially supported by the Japanese Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research (KAKENHI) numbers for Hiroshi Nishiura: 16KT0130, 16K15356, and 17H04701, Ryota Matsuyama with 16H06581, and Shinya Tsuzuki with 17H06487. Hiroshi Nishiura received funding from the Japan Agency for Medical Research and Development, JSPS Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers, The Telecommunications Advancement Foundation, Inamori Foundation, and the Japan Science and Technology Agency (JST) Core Research for Evolutional Science and Technology (CREST) program (JPMJCR1413). Akira Endo was supported by The Nakajima Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.