Table 2. Infectious causes and explanations for unexplained deaths and critical illnesses cases, 1995–1998, California, Oregon, Connecticut, and Minnesota (n=34)^a,b.

Syndrome	Etiology (n)	Tests (n)
Neurologic (n=15)	Neisseria meningitidis (4)	16S rDNA PCR (2), PCR (1), EIA IgM (1)a
	Bartonella hensaelae (1)	PCR, IFA, IgG
	Bartonella spp. (2)	IFA, IgG
	Chlamydia pneumoniae (1)	MIF, IgG
	Mycoplasma pneumoniae (1)	EIA, IgM/IgG
	Cytomegalovirus (1)	EIA and IFA,IgG
	Coxsackie B (1)	EIA,IgM, viral culture
	Enterovirus (1)	EIA,IgM
	Epstein-Barr virus (1)	IFA,IgG (VCA and EA)
	Human herpes virus 6 (1)	IFA and EIA (IgM and IgG)
	Mumps virus (1)	IFA IgM, IFA and EIA, IgG
Respiratory (n=13)	Chlamydia pneumoniae (2)	MIF IgG (2), IFA, IgM
	Mycoplasma pneumoniae (4)	PCR (blood), EIA, IgM/IgG
	Streptococcus pneumoniae (2)	16S rDNA PCR (pleural fluid)
	Legionella spp. (1)	PCR (from lung)
	Adenovirus (1)	EIA and IFA, IgG
	Influenza B virus (1)	EIA and IFA, IgG
	Influenza A virus (1)	EIA and IFA, IgM, EIA (IgG)
	Human parainfluenza virus types 1 and 3 (1)	EIA and IFA, IgG
Cardiac (n=3)	Borrelia burgdorferi/Ehrlichia chaffeensis (1)	EIA/IFA flagella, IgG, Western Blot (IgG and IgM)
	Enterovirus (1)	EIA IgM
	Legionella spp. (1)	PCR (heart)
Multisystem (n=3)	Neisseria meningitidis (1)	PCR (cerebrospinal fluid)
	Adenovirus (1)	PCR (blood)
	Enterovirus (1)	IgM, EIA

^a PCR, polymerase chain reaction; EIA, enzyme immunosorbent assay; IFA, indirect immunofluorescent assay; IG, immunoglobulin; MIF, microimmunofluorescence.

^bReference 12.