Volume 21, Number 2—February 2015
CME ACTIVITY - Research
Infectious Causes of Encephalitis and Meningoencephalitis in Thailand, 2003–2005
Table 1
Classification strategy for etiology of encephalitis, Thailand, 2003–2005*
Agent | Established cause of encephalitis | Diagnostic category |
||
---|---|---|---|---|
Confirmed | Probable | Possible | ||
Bacteria | ||||
Bartonella henselae | Yes | ≥4-fold rise serum Ab titer (IFA) | ||
Haemophilus influenzae | Rare | CSF or blood culture positive CSF latex agglutination positive | ||
Mycobacterium tuberculosis | Rare | CSF culture positive | ||
Mycoplasma pneumoniae | Yes | CSF PCR positive | Serologic conversion (neg to pos) on serum Ab titer (EIA) | OP PCR positive |
Neisseria meningitidis | Rare | CSF or blood culture positive CSF latex agglutination positive | ||
Rickettsia spp. (e.g., Rickettsia conorii, Orientia tsutsugamushi) | Yes | >4-fold rise serum Ab titer | ||
Streptococcus pneumoniae | Rare | CSF or blood culture positive; CSF latex agglutination positive | ||
Treponema pallidum | Yes | CSF VDRL positive | Blood specific treponemal Ab positive | |
Other | Rare (organism dependent) | CSF or blood culture positive; CSF 16S RNA PCR positive + sequence (organism dependent) | CSF 16S RNA PCR positive + sequence (organism dependent) | Blood culture positive (organism dependent) |
Fungi | ||||
Cryptococcus spp. | Yes (in immunocompromised patients) | CSF culture positive; India ink positive; cryptococcal antigen positive | ||
Parasites | ||||
Malaria parasites | Yes | Thick or thin smear positive in presence of malarial disease | ||
Other parasites (e.g., Toxoplasma gondii) | Yes (parasite dependent) | Detection of parasites in CSF or brain | ||
Viruses | ||||
Adenoviruses | Yes (except for enteric HAdV 40, 41) | CSF PCR positive (other than HAdV 40, 41) | ≥4-fold rise serum Ab titer (EIA); OP PCR positive; CSF PCR positive for HAdV 40, 41 | |
Chikungunya virus | Rare | IgM in CSF with CHIKV PRNT titer >1:10 in CSF or serum | >4-fold rise in neutralizing Ab titers in serum | |
Cytomegalovirus (Human herpesvirus 5) | Yes (mostly in immunocompromised patients) | CSF PCR positive | ||
Dengue virus | Rare | DENV RNA in serum or CSF; DENV IgM in serum with a DENV PRNT90 titer >1:20 and a DENV PRNT90 to JEV PRNT90 titer ratio >1:4 | ||
Enteroviruses | Yes | CSF isolation in culture; CSF PCR positive | 4-fold rise Ab titer | |
Epstein-Barr virus (human herpesvirus 4) | Yes, dependent on clinical situation | CSF PCR positive (predictive value in immunocompetent hosts is unclear) | ||
Herpes simplex viruses 1 and 2 | Yes | CSF PCR positive | CSF IgM present | |
Human herpesvirus 6 | Yes | CSF PCR positive | ||
Human herpesvirus 7 | Yes (in immunocompromised patients), not well established | CSF PCR positive | ||
HIV | Yes | Serology with Western blot positive | ||
Influenza viruses | Rare | >4-fold rise serum Ab titer | OP PCR positive | |
Japanese encephalitis virus | Yes | JEV IgM in CSF; JEV IgM in serum with a JEV PRNT90 titer >1:20 and a JEV PRNT90 to DENV PRNT90 titer ratio >1:4 | JEV IgM in serum with a JEV PRNT90 titer >1:20 but a JEV PRNT90 to DENV PRNT90 titer ratio <1:4 | |
Measles virus | Yes | CSF Ab positive | >4-fold rise serum Ab titer if no recent vaccination | |
Mumps virus | Yes | CSF Ab positive | >4-fold rise serum Ab titer if no recent vaccination | |
Nipah virus | Yes | CSF PCR positive; 4-fold rise serum Ab titer | ||
PIV 1, 2, and 3 | No (PIV1, 2) Yes (PIV3) | >4-fold rise serum Ab titer (EIA); OP PCR positive | ||
Rabies virus | Yes | >1 positive test: CSF PCR positive; saliva PCR positive | IgG detected in convalescent serum | |
Rubella virus | Yes | CSF Ab positive | >4-fold rise serum Ab titer if no recent vaccination | |
Varicella-zoster virus (human herpesvirus 3) | Yes | CSF PCR positive | ||
WNV | Yes | IgM in CSF; IgM in serum with a WNV PRNT titer >1:20 and >1:4-fold higher than JEV and DENV titer | IgM in serum with a WNV PRNT title >1:20 but <1:4-fold higher than JEV and DENV titer |
*Ab, antibody; CHIKV, chikungunya virus; CSF, cerebrospinal fluid; EIA, enzyme immunoassay; IFA, immunofluorescence assay; OP, oropharyngeal swab sample; PRNT90, 90% plaque reduction neutralization test; HAdV, human adenoviruses; DENV, dengue virus; JEV, Japanese encephalitis virus; PIV, parainfluenza virus; WNV, West Nile virus. Blank cells indicate not applicable.
1These authors contributed equally to this article.
2Members are listed at the end of this article.