Table 1. Pathogens that are the key causes of AD.

Pathogens	Refs.
Viruses Human herpesvirus 1 (HHV-1) Human herpesvirus 2 (HHV-2) Cytomegalovirus (CMV), (HHV-3) Epstein-Barr virus (EBV), (HHV-4) Varicella-zoster virus (VZV), (HHV-5) Human herpesvirus 6 (HHV-6) Hepatitis C virus (HCV)	[3, 32] [32, 33] [3, 32] [3, 32] [3, 34] [3, 32] [35]
Bacteria Chlamydia pneumoniae Helicobacter pylori Borelia burgdorferi Treponema pallidum Porphyromonas gingivalis Fusobacterium nucleatum Prevotella intermedia and other periodontal bacteria	[36, 37] [3, 36, 37] [36, 37] [38, 39] [32, 36, 40] [40] [40]
Fungi Candida albicans	[41, 42]
Protozoa Toxoplasma gondii	[37]