The book The Coming Plague lists the following factors: Social changes ​ — especially the practice of having multiple sex partners — ​ led to a wave of sexually transmitted diseases, making it much easier for the virus to take hold and for one carrier to infect many other people.
तसेच, अब्जावधी डॉलरच्या जागतिक रक्‍त व्यापारामुळेही एड्‌स व्हायरस एका रक्‍तदात्याकडून कित्येक ग्राहकांच्या शरीरात पोचण्याचा मार्ग मोकळा झाला.