BackgroundData on encephalitis in Thailand have not been completely described. Etiologies remain largely unknown. We prospectively analyzed 103 Thai patients from 27 provinces for the causes of encephalitis using clinical, microbiological and neuroimaging indices; caseswithout a diagnosis were evaluated for autoimmune causes of encephalitis.MethodsPatients with encephalitis and/or myelitis were prospectively studied between October 2010 and August 2012. Cases associated with bacterial, rickettsial and mycobacterial diseases were excluded. Herpes viruses 1-6 and enteroviruses infection was diagnosed using PCR evaluation of CSF; dengue and JE viruses infection, by serology. The serum of test-negative patients was evaluated for the presence of autoantibodies.Results103 patients were recruited. Fifty-three patients (52%) had no etiologies identified. Twenty-five patients (24%) were associated with infections. Immune encephalitis was found in 25 (24%); neuropsychiatric lupus erythematosus (4), demyelinating diseases (3), Behcet’s disease (1) and the remaining had antibodies to NMDAR (5), ANNA-2 (6), Yo (2), AMPA (1), GABA (1), VGKC (1) and NMDA coexisting with ANNA-2 (1). Presenting symptoms in the autoimmune group included behavioral changes in 6/25 (versus 12/25 in infectious and 13/53 in unknown group) and as psychosis in 6/25 (versus 0/25 infectious and 2/53 unknown). Seizures were found in 6/25 autoimmune, 4/25 infectious and 19/53 unknown group. Two patients with anti-ANNA-2 and one anti-Yo had temporal lobe involvement by magnetic resonance imaging. Two immune encephalitis patients with antibodies to NMDAR and ANNA-2 had ovarian tumors.ConclusionsAutoantibody-associated encephalitis should be considered in the differential diagnosis and management algorithm regardless of clinical and neuroimaging features.

BackgroundHerpes simplex virus (HSV) is the most common cause of sporadic encephalitis worldwide. The high mortality rate (70–80 %) of herpes simplex encephalitis (HSE) can be reduced to 20–30 % by antiviral therapy. However, normocellular CSF can lure physicians to look for non-infectious causes, resulting in delayed treatment. This study aimed to investigate, characterize and differentiate HSE patients, with normocellular and pleocytosis CSF, according to neuroimaging patterns, underlying disease, CSF viral load and clinical outcome. Patients with proven (by PCR positive CSF) or presumed viral infections of the CNS admitted to King Chulalongkorn Memorial Hospital between January 2002 and 2011 were analyzed.ResultsHSV was detected in the CSF of 43 patients but only 23 patients had encephalitis. Among these 23 patients, 6 cases (26.1 %) had normal CSF WBC (<5 cells/mm3). One patient in this normocellular CSF group had HIV infection. Although this patient had low CD4 counts (<200 cells/mm3), the peripheral WBC counts showed only mild leukopenia. The CSF HSV viral load in the pleocytosis group was higher than the normocellular group, with an average of 12,200 vs 3027 copies/ml respectively. There was no correlation between the viral load and the clinical outcome. With respect to neuroimaging, 4 (66.7 %) patients in the normocellular group had unremarkable/non-specific results.ConclusionsNormocellular CSF in HSE is not rare, and can be seen in normal as well as immunocompromised hosts. Clinicians should not exclude CNS infection, especially HSE, merely based on the absence of CSF pleocytosis and/or unremarkable neuroimaging study.

BackgroundThe incidence of autoimmune encephalitis has risen globally. There are two general categories of disease-associated antibodies that can be tested for: neuronal surface and intracellular. However, testing both groups of autoantibodies are costly. This study aims to identify differences between groups by comparing clinical presentations, radiological findings and CSF profile of patients, and determine if any parameters are indicative of one group of autoantibodies over another. Additionally, we aim to report the local incidence of less common groups of disease-associated antibodies as well.MethodsSeventy-seven records of autoimmune encephalitis/encephalomyelitis patients admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between October 2010 and February 2017 were reviewed. Patients with infections or those with classic central nervous system demyelinating features were excluded.ResultsOf 77 patients, 40% presented with neuronal surface antibodies and 33% had intracellular antibodies. The most common autoantibody detected in each group was anti-NMDAr antibody (25/31, 81%) and anti-Ri antibody (7/25, 28%) respectively. In the neuronal surface antibody group, behavioral change was the most common complaint (45%), followed by seizures (39%) and abnormal movements (29%). In the latter group, seizure was the most common presenting symptom (32%), followed by motor weakness (20%), behavioural change (16%) and abnormal movements (16%). Patients with neuronal surface antibodies were younger (35 vs 48 years old, p = 0.04) and more likely to present with behavioral change (45% vs 16%, p = 0.02). Mortality rate was higher in the intracellular group (16% vs 3.2%, p = 0.09). No differences were detected in magnetic resonance imaging (MRI) and CSF profile.ConclusionsIn the early stages of the disease, both groups have comparable clinical outcomes. Although there were significant differences in age and percentage of patients with behavioral change, both groups of autoimmune encephalitis still shared many clinical features and could not be distinguished based on MRI and CSF profiles. Therefore, we recommend that patients with features of autoimmune encephalitis should be screened for both the neuronal surface and intracellular antibodies regardless of clinical presentation.

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Food poisoning or gastroenteritis is a common diagnosis for individuals who have nausea, vomiting and diarrhea after ingestion of fish. When also manifesting neurological symptoms, these are blamed on puffer fish poisoning, but ciguatera fish poisoning (CFP) can also manifest only with gastroenteritis, without neurological complications and remain undiagnosed. We report patients who fulfilled criteria of CFP suffering from severe GI disturbances, neurological manifestations, compromised cardiovascular status and autonomic dysfunction. All recovered within 1-3 days with supportive treatment. There were two small outbreaks: one in Bangkok in 2007 (2 patients) and another (2009) in Phuket (4 patients). All patients consumed the same unidentified fish portion and had severe GI symptoms. One had acute ventilatory failure requiring intubation whereas the remaining had neurological disturbances consisting of paresthesia, severe vertigo and ataxia. Absence of reflex tachycardia was noted in all patients who had severe volume depletion and shock. The most severe patient could be extubated within 24 hours and was discharged in 48 hours. All of the remaining recovered completely within 48 hours. Severe abdominal pain, nausea and vomiting and autonomic dysfunction in the form of bradycardia in the presence of hypotension were seen. Dramatic recovery within 48 hours occurred in all cases. None of the fish considered to have been responsible was available for testing. Physicians should be aware of CFP intoxication in the differential diagnosis of gastroenteritis-like syndromes after eating seafood.

From 2013 to 2018, the Thai Red Cross Emerging Infectious Disease–Health Science Center (TRC-EID-HS), in collaboration with the Department of Disease Control (DDC) and the Ministry of Public Health (MOPH) Thailand, conducted encephalitis surveillance. A total of 1700 cerebrospinal fluid (CSF) samples from patients with encephalitis were tested by a predesigned multiplex PCR. Diagnosis was made in 318 cases (18.7%), 86 (27%) of which were caused by Epstein–Barr virus (EBV), 55 (17.3%) by enteroviruses (EV), 36 (11.3%) by varicella–zoster virus (VZV), 31 (9.7%) by cytomegalovirus (CMV), 25 (7.8%) by herpes simplex virus type 1 (HSV-1), and 20 (6.3%) by human herpesvirus 6 (HHV-6). Results were compared with 3099 CSF samples from patients with encephalitis collected between 2002 to 2012, which were tested by specific PCR assays. Diagnosis was made in 337 (10.9%) of these cases, and 91 (27%) were CMV, 79 (23.4%) were VZV, 72 (21.4%) were EBV, 39 (11.6%) were EVs, 39 (11.6%) were HSV-1, 33 (9.8%) were HSV-2, and 2 (0.6%) were Dengue virus (DENV). The change in the pattern toward EVs as a major cause of viral encephalitis was unexpected, and a change in viral neurotropism may be responsible.

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In 2014, two unusual peaks of H1N1 influenza outbreak occurred in Nakhon Ratchasima Province, in Thailand. Among 2,406 cases, one of the 22 deaths in the province included a 6-year-old boy, who initially presented with acute necrotizing encephalopathy. On the other hand, his sibling was mildly affected by the same influenza virus strain, confirmed by whole-genome sequencing, with one silent mutation. Absence of acute necrotizing encephalopathy and other neurological illnesses in the family and the whole province, with near identical whole viral genomic sequences from the two siblings, and an absence of concomitant severe lung infection (cytokine storm) at onset suggest nonpermissive infection as an alternative pathogenetic mechanism of influenza virus.