Major bat-borne zoonotic viral epidemics in Asia and Africa: A systematic review and meta-analysis

Abstract

Bats are the natural reservoir host for many pathogenic and non-pathogenic viruses, potentially spilling over to humans and domestic animals directly or via an intermediate host. The ongoing COVID-19 pandemic is the continuation of virus spillover events that have taken place over the last few decades, particularly in Asia and Africa. Therefore, these bat-associated epidemics provide a significant number of hints, including respiratory cellular tropism, more intense susceptibility to these cell types, and overall likely to become a pandemic for the next spillover. In this systematic review, we analysed data to insight, through bat-originated spillover in Asia and Africa. We used STATA/IC-13 software for descriptive statistics and meta-analysis. The random effect of meta-analysis showed that the pooled estimates of case fatality rates of bat-originated viral zoonotic diseases were higher in Africa (61.06%, 95%CI: 50.26 to 71.85, l² % = 97.3, p < 0.001). Moreover, estimates of case fatality rates were higher in Ebola (61.06%; 95%CI: 50.26 to 71.85, l² % = 97.3, p < 0.001) followed by Nipah (55.19%; 95%CI: 39.29 to 71.09, l² % = 94.2, p < 0.001), MERS (18.49%; 95%CI: 8.19 to 28.76, l² % = 95.4, p < 0.001) and SARS (10.86%; 95%CI: 6.02 to 15.71, l² % = 85.7, p < 0.001) with the overall case fatality rates of 29.86 (95%CI: 29.97 to 48.58, l² % = 99.0, p < 0.001). Bat-originated viruses have caused several outbreaks of deadly diseases, including Nipah, Ebola, SARS and MERS in Asia and Africa in a sequential fashion. Nipah virus emerged first in Malaysia, but later, periodic outbreaks were noticed in Bangladesh and India. Similarly, the Ebola virus was detected in the African continent with neurological disorders in humans, like Nipah, seen in the Asian region. Two important coronaviruses, MERS and SARS, were introduced, both with the potential to infect respiratory passages. This paper explores the dimension of spillover events within and/or between bat-human and the epidemiological risk factors, which may lead to another pandemic occurring. Further, these processes enhance the bat-originated virus, which utilises an intermediate host to jump into human species.

Keywords: bat-human interface; bats; epidemic; intermediate host; outbreak; spillover; zoonotic virus.

FIGURE 1

Systematic review PRISMA flow diagram describing the selection of published articles on bat‐originated zoonotic diseases in humans in Asia and Africa, and inclusion/exclusion process used in the study

FIGURE 2

Reported countries (Asia and Africa) of Nipah, MERS, SARS and Ebola with number of studies conducted showed in the global map

FIGURE 3

Forest plot of the estimated case fatality rates of bat‐originated viral zoonotic diseases in Asian and African countries (the centre dot representing point estimates whereas grey square representing the weight of each study to the meta‐analysis)

FIGURE 4

Forest plot of the estimated case fatality rates of bat‐originated viral zoonotic diseases in human (the centre dot representing point estimates whereas grey square representing the weight of each study to the meta‐analysis)

FIGURE 5

Transmission dynamics of Nipah, MERS, SARS and Ebola between bats and humans and further transmission among humans to humans through direct contact