TABLE 3.

Classification of human pathogens based on damage as a function of immune response^a

Class	Pathogen	Damage as a magnitude of the immune responseb
		Weak	Intermediate	Strong
1	Legionella pneumophila	Legionnaire’s disease	None	None
	Pneumocystis carinii	Pneumonia	None	None
	Pseudallescheria boydii	Invasive sinusitis, pneumonia	None	None
	Staphylococcus epidermidis	Vascular infections	None	None
2	Adenovirus	Pneumonia, disseminated infection	Upper respiratory infection, diarrhea, hemorrhagic cystitis	None
	Alphaviruses	Encephalitis	Encephalitis	None
	Bacillus anthracis	Anthrax	Anthrax	None
	Blastomyces dermatitidis	Disseminated blastomycosis	Pneumonia	None
	Bordetella pertussis	Secondary pneumonia	Pertussis	None
	Borrelia burgdorferi	Persistence of infection with arthritis and meningitis	Lyme disease	None
	Brucella spp.	Brucellosis	Brucellosis	None
	Candida spp.	Mucocutaneous candidiasis	Vaginal candidiasis	None
	Clostridium tetani	Tetanus	Tetanus	None
	Clostridium botulinum	Botulism	Botulism	None
	Corynebacterium diphtheriae	Diphtheria	Diphtheria	None
	Cryptococcus neoformans	Meningoencephalitis	Primary complex in lung, pneumonia, meningoencephalitis	None
	Cryptosporidium spp.	Chronic diarrhea	Diarrhea	None
	Ebola virus	Hemorrhagic fever	Hemorrhagic fever	None
	Entamoeba histolytica	Amebiasis	Amebiasis	None
	Francisella tularensis	Disseminated infection	Tularemia	None
	Group B streptococcus	Invasive infection	Puerperal sepsis	None
	Haemophilus influenzae type b	Disseminated infection	Upper respiratory infection, meningitis	None
	Hemophilus ducreyi	Disseminated infection	Chancroid	None
	Hepatitis A virus	Hepatitis	Hepatitis	None
	JC virus	Hemorrhagic cystitis, ureteral stenosis, progressive multifocal leukoencephalopathy	Asymptomatic	None
	Listeria monocytogenes	Listeriosis	Listeriosis	None
	Molluscum virus	Disseminated molluscum	Molluscum contagiosum	None
	Neisseria gonorrhoeae	Disseminated infection	Urethritis, PID	None
	Neisseria meningitidis	Meningococcemia carrier state	Meningitis	None
	Paracoccidioides brasiliensis	Disseminated infection	Pneumonia	None
	Parvovirus	Aplastic and chronic anemia	Erythema infectiosum	None
	Plasmodium spp.	Malaria	Malaria	None
	Pseudomonas aeruginosa	Pneumonia, systemic infection	Diarrhea	None
	Rhinovirus	Upper respiratory infection	Upper respiratory infection	None
	Rickettsia rickettsii	Rocky mountain spotted fever	Rocky mountain spotted fever	None
	Rochalimaea spp.	Bacillary angiomatosis	Bacillary angiomatosis	None
	Rotavirus	Diarrhea	Diarrhea	None
	Streptococcus pneumoniae	Pneumonia, meningitis, pneumococcal sepsis	Pneumonia, meningitis	None
	Toxoplasma gondii	Toxoplasmosis	Cervical lymphadenopathy	None
	Trichomonas vaginalis	Trichomoniasis	Trichomoniasis	None
	Varicella-zoster virus	Disseminated infection	Varicella, dermatomal zoster	None
	Vibrio cholera	Diarrhea	Diarrhea	None
	Yersinia pestis	Septicemic, pneumonic and meningeal plague	Bubonic plague	None
3	Chlamydia pneumoniae	Pneumonia	Pneumonia	Asthma(?), atherosclerosis(?)
	Coccidioides immitis	Disseminated coccidioidomycosis	Pneumonia	Erythema nodosum, erythema multiforme
	Cytomegalovirus	Pneumonitis, hepatitis, retinitis	Mononucleosis	Guillain-Barré syndrome
	Escherichia coli O157:H7	Diarrhea	Diarrhea	Hemolytic uremic syndrome
	Epstein-Barr virus	Hairy leukoplakia, lymphoproliferative disorders	Mononucleosis	Burkitt’s lymphoma, nasopharyngeal carcinoma
	Streptococcus pyogenes	Scarlet fever, erysipelas, toxic shock syndrome	Scarlet fever, erysipelas, toxic shock syndrome	Rheumatic fever glomerulonephritis
	Hepatitis B virus	Chronic infection	Hepatitis	Hepatocellular carcinoma
	Herpes simplex virus 2	Genital herpes, disseminated herpes	Genital herpes, neonatal herpes, encephalitis	Cervical cancer
	Herpes simplex virus 1	Gingivostomatitis, esophagitis, pneumonitis	Gingivostomatitis, encephalitis	Oropharingeal carcinoma
	Histoplasma capsulatum	Disseminated histoplasmosis	Primary complex in lung	Fibrosing mediastinitis
	Human immunodeficiency virus	AIDS	AIDS	Sjogren-like syndrome(?)
	Influenza virus	Influenza	Influenza	Reye syndrome(?), Guillain-Barré syndrome, transverse myelitis
	Leishmania spp.	Visceral leishmaniasis	Leishmaniasis	Glomerulonephritis
	Measles virus	Severe measles, giant cell pneumonia	Measles	Atypical measles, SSPE
	Mycobacterium tuberculosis	Pulmonary and disseminated tuberculosis	Primary complex in lung, latent infection	Scar carcinoma, constrictive pericarditis, fibrosing mediastinitis
	Papilloma virus	Warts, condyloma acuminata, neoplasia	Warts, condyloma acuminata, neoplasia	Neoplasia
	Respiratory syncytial virus	Severe pneumonia	Pneumonia, bronchiolitis	Hyperactive airways?
	Salmonella spp.	Salmonellosis chronic carrier	Enteric fever	Reiter syndrome
	Staphylococcus aureus	Suppurative infections, toxic shock syndrome, endovascular infections	Suppurative infections, endovascular infections	Toxic shock syndrome
	Treponema pallidum	Accelerated course	Primary and secondary syphilis	Obliterative endarteritis, tertiary syphilis
	Yersinia enterocolitica	Septicemia	Enterocolitis	Reactive polyarthritis
4	Aspergillus spp.	Invasive aspergillosis	None	Allergic sinusitis, Farmer’s lung
	Vaccinia virus	Vaccinia necrosum	None	Encephalitis
5	Mycoplasma pneumoniae	Pneumonia	Pneumonia	Raynoud’s phenomenon, Guillain-Barré, erythema multiforme
	Chlamydia trachomatis	Trachoma, perinatatal infections, lymphogranulama venereum	Trachoma, perinatatal infections, lymphogranulama venereum	Reiter’s syndrome, infertility, ectopic pregnancy, spontaneous abortions
	Mumps virus	Mumps	Mumps	Diabetes(?), encephalitis
	Campylobacter jejuni	Diarrhea	Diarrhea	Reiter’s syndrome
	Poliovirus	Poliomyelitis	Poliomyelitis	Postmyelitis syndrome
	Shigella spp.	Diarrhea	Diarrhea	Reiter’s syndrome
	Trematoda spp.	Schistosomiasis	Schistosomiasis	Portal and pulmonary hypertension, bladder neoplasia
	Trypanosoma spp.	Trypanosomiasis	Trypanosomiasis	Cardiomyopathy
6	Helicobacter pylori	None associated	None associated	Gastric gastritis, carcinoma, lymphoma

^aNot a complete list of all pathogens. 

^bThe terms weak, intermediate, and strong include qualitative and quantitative aspects of the host response. For examples of weak and strong responses see Table 2. The intermediate category is the most common type of response in a healthy population and the conditions listed under this category can occur in healthy individuals. SSPE, subacute sclerosing panencephalitis; PID, pelvic inflammatory disease.