Figure 5.

The very strong El Niño events and viral outbreaks of CoVs and AIVs A. The recent and historic CoV outbreaks are displayed over time based on assumptions that these CoV outbreaks are not isolated events. The three recently-recorded El Niño events (blue triangles) are 1982–1983, 1997–1998, 2015–2016. Two porcine CoV outbreaks are also indicated (below the horizontal arrowed bar for time), PEDV (porcine epidemic diarrhea virus, an alphacoronavirus) and SADS-CoV (swine acute diarrhea syndrome, an alphacoronavirus) [56]. B. A historic study based on HP H5N1 AIV genome sequences in segments (blue oval circles with 8 solid bars; red, segments of the Old group; green, segments of the New group). Two genome types once had dwelled in a near-by islands (red and blue frames), the New (red) and the Old (green) groups. They were carried to China through the flyway by migratory birds seen as sampling the local populations (shared territories, green dashed frames) until the mixing population (1/4 over each other) were destroyed by the strong El Niño event in 1997–1998 (red dashed frames). The process started again after 2001 and reached its half way in 2003. The complete takeover of Old group’s territory happened after 2005. This takeover had struggled in a time period of ∼ 10 years, with matching point around 2003 (blue dashed frames). An obvious slow-down point is around 1997, a showdown by nature, the yet-strongest El Niño event in the recent history, and it was within the recovery phase, 2003 when HP H5N1 and SARS-CoV outbreaks both happened in China. This plot is reproduced based on data from reference [35], where genome segments of the old and the new groups are counted as percentages of the total.