Anti-rabies virus IgM in serum and cerebrospinal fluid from rabid dogs.

An anti-rabies IgM antibody capture radio immunoassay was used to test serum and cerebrospinal fluid from 37 dogs held in quarantine for suspicion of rabies. Rabies was confirmed in dogs that died by mouse inoculation and subsequent examination of mouse brains by fluorescent antibody technique to detect rabies antigen. The mean counts per minute (CPM) of iodinated anti-rabies gamma globulin coupled IgM rabies antibody in CSF and serum from rabid dogs were significantly higher than in CSF and serum from non-rabid dogs. Mean CPM from rabid dogs was greater in CSF than in sera, in contrast with non-rabid dogs, from which mean cpm was higher in sera than CSF, suggesting that antibody may have been synthesized in the CSF. To evaluate this test further, a dog was infected by rabies virus, and serial serum and CSF specimens were collected until the time of death. IgM anti-rabies antibody developed in the CSF and serum 29 days following infection, and rose just before the dog died of rabies on day 34. The rabies MAC RIA is potentially useful as a diagnostic method in quarantined dogs with rabies-like illness. Perhaps more importantly, it may be applied to better understand the immunopathogenicity of rabies.

Intense transmission of Japanese encephalitis virus to pigs in a region free of epidemic encephalitis.

Epidemic Japanese encephalitis recurs annually in the northern provinces of Thailand, but in the southern provinces cases of human encephalitis are rare. We investigated transmission of Japanese encephalitis virus (JEV) to pigs in southern Thailand. Blood specimens from one hundred young pigs at abattoirs in three southern provinces were tested for JEV hemagglutination inhibiting (HAI) antibodies. Seventy-four percent were positive. Ten seronegative sentinel pigs were placed at five locations in one southern province. Seven of the ten pigs developed JEV HAI and JEV IgM ELISA antibodies within two weeks of placement. JEV was isolated from all seven seroconverting sentinel pigs from blood specimens collected 3 to 11 days after placement. Fifteen light-trap mosquito collections at the five locations all included known JEV vectors, some in large numbers. We conclude that there is intense transmission of JEV to pigs in southern Thailand despite the rare occurrence of human encephalitis in the same region.