What caused the outbreak in World War Z?

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Tags

1. #archeological
2. #likely
3. #scavenging
4. #artifacts
5. #chinese
6. #basin
7. #caused
8. #start
9. #patient
10. #three
11. #under
12. #flood
13. #young
14. #however
15. #zombie
16. #movie
17. #submerged
18. #bitten
19. #gorges
20. #virus
21. #world
22. #water
23. #river