Implications of the COVID-19 lockdown on dengue transmission in Malaysia

  1. Song-Quan Ong
  2. Hamdan Ahmad
  3. Ahmad Mohiddin Mohd Ngesom

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Abstract

The impact of movement restrictions during the COVID-19 lockdown on the existing endemic infectious disease dengue fever has generated considerable research interest. We compared the Malaysia weekly epidemiological records of dengue incidences during the period of lockdown to the trend of previous years (2015 to 2019) and a simulation at the corresponding period that expected no movement restrictions. We found that the dengue incidence declined significantly with a greater magnitude at phase 1 of lockdown, with a negative gradient of 3.2-fold steeper than the trend observed in previous years and 6.5-fold steeper than the simulation, indicating that the control of population movement did reduce dengue transmission. However, starting from phase 2 of lockdown, the dengue incidences demonstrated an elevation and earlier rebound by at least 4 weeks and grew with an exponential pattern compared to the simulation and previous years. Together with our data on Aedes mosquitoes from a district of Penang, Malaysia, we revealed that Aedes albopictus is the predominant species for both indoor and outdoor environments. The abundance of the mosquito was increasing steadily during the period of lockdown, and demonstrated strong correlation with the locally reported dengue incidences; therefore, we proposed the possible diffusive effect of vector that led to a higher acceleration of incidence rate. These findings would help authorities review the direction and efforts of the vector control strategy.

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  1. Version published to 10.1101/2020.07.21.214056v2 on bioRxiv
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    SciScore for 10.1101/2020.07.21.214056: (What is this?)

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    Table 1: Rigor

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    Table 2: Resources

    Software and Algorithms
    SentencesResources
    The counts of Ae. aegypti and Ae. albopictus from indoor and outdoor locations for the eight stages of the time series during partial lockdown were obtained and correlated with the weekly reported dengue incidences of Penang, Malaysia by using Spearman rank correlation at the significance level of 0.05 (SPSS 17.0, IBM Corp.).
    SPSS
    suggested: (SPSS, RRID:SCR_002865)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    In contrast to Harrington et al. [32], who argued that people, rather than mosquitoes, rapidly move the virus within and between rural communities and places due to the limitation of the flight range of female Ae. aegypti, our result of Aedes mosquitoes revealed that the element of vector dispersal plays a more crucial role in spreading the virus, when the abundance growth of the sampling locations correlated strongly with locally reported dengue incidences. We also suggest that Ae. albopictus could be the key substitution vector that contributes significantly to dengue virus circulation, and therefore, the vector control direction and strategies should be redesigned. With no specific previous entomological data about female adult Ae. albopictus in the corresponding period with lockdown, we refer to Rozilawati et al. [14] and Rahim et al. [33], who studied the seasonal abundance of Ae. albopictus in Penang by sampling eggs, the Ovitrap index, the container index (CI), the house index (HI) and the Breteau Index (BI). Their results demonstrated that the indexes of Ae. albopictus for the corresponding period of phase 2 to 4 of lockdown should be lower, in contrast to our finding that the abundance of Ae. albopictus increased steadily from phases 1 to 5. There are several reasons for the increase in Ae. Albopictus. First, as proposed by the WHO [34], the upsurge of Aedes mosquitoes may be due to the southwestern monsoon (end of May to September), which brought a higher frequency ...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • No funding statement was detected.
    • No protocol registration statement was detected.

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  3. Version published to 10.1101/2020.07.21.214056v1 on bioRxiv