Channarong Mitmoonpitak

Rabies in Thailand

The prevalence of canine and human rabies in Thailand has decreased significantly during the last decade. This has been associated with an increasing number of human post-exposure treatments. Educational efforts, mass vaccination of dogs and cats and the use of safe and effective vaccines have all made an impact. The proportion of fluorescent antibody positive dogs, among those examined for rabies averaged 54% indicating that rabies is still a major public health threat. Canine rabies vaccination is not usually performed in animals < 3 months old. However, this study revealed that 14% of rabid dogs were < 3 months old and 42% were < or = 6 months old. This is the age group most likely to interact with humans and other dogs. Our study also supports the World Health Organizations recommendation that observing suspected rabid dogs for 10 days is an adequate and safe practice.

Survival of Naturally Infected Rabid Dogs and Cats

A total of 1820 dogs and 332 cats that appeared ill or had bitten humans or animals were observed for >or=10 days. Of these, 957 dogs and 94 cats that were confirmed to be rabid survived <10 days after admission to our institution. This study supports current recommendations that dogs and cats that are suspected of being rabid should be euthanized and examined or, if this is inappropriate, confined and observed for 10 days.

Fluorescent Antibody Test for Rabies: Prospective Study of 8,987 Brains

A prospective study of 8,987 canine, feline, human, and other mammalian brains (and one avian brain) was undertaken. The brains were analyzed for rabies antigens; two samples were obtained from each brainstem, and one sample was obtained from each hippocampus. The samples were stained with rabies conjugate and examined by use of fluorescence microscopy. There were no false-negative results. We conclude, therefore, that postexposure rabies treatment is not requisite in all cases, provided that the fluorescent antibody test is performed without delay in a laboratory experienced with the procedure and microscopy results are fluorescent negative.

Potency, sterility and immunogenicity of rabies tissue culture vaccine after reconstitution and refrigerated storage for 1 week

The economical Thai Red Cross intradermal (TRC-ID) post-exposure rabies treatment schedule is now widely used in Asia. However, directives from WHO and manufacturers mandated that the vaccine be used within 8h after reconstitution of the freeze-dried product. This limits the use of TRC-ID to large animal bite clinics that see several rabies exposed patients daily. This study demonstrated that refrigerated purified chick embryo and Vero cell rabies vaccines can be stored safely for up to 7 days after reconstitution; allowing use of this treatment regimen in clinics that see few rabies exposed subjects. A large project applying this method in a Northern Thai canine rabies endemic province is now in place.

Diffusion and fate of intramuscularly injected human rabies immune globulin

The importance of rabies immune globulin (RIG) in postexposure rabies treatment is well known and it has been emphasized that the local injection into the animal bite sites is crucial. This preliminary study used a radioisotope tracer that allows following the fate of human rabies immune globulin (HRIG) injected intramuscularly. There was significant retention and local diffusion of the immune globulin at the injection site and significant radiotracer could still be detected at the site 24 h later.

Screening of upregulated genes in suckling mouse central nervous system during the disease stage of rabies virus infection.

The pathogenesis of hydrophobia remains unclear. The aim of this study was to identify the differentially upregulated genes that correlated with disease development in an experimental mouse model to provide better understanding of pathological mechanisms in rabies. The present work employed Clontech mouse array 1.2 II containing 1,176 gene transcripts. Suckling mice were intracerebrally infected with canine rabies virus. The gene expression profiles on day 2, 4 and 6 post inoculation were followed. The results show genes whose expression increased at least twofold above the control, mock‐infected brain. The numbers of genes showing altered expression level were 29, 109 and 98 genes on day 2, 4 and 6, respectively. The genes with altered expression were classified into eight major groups, namely immune response, metabolism, receptor and transporter, growth factors, death mediated factors, transcription and translation factors, proteases, and kinases. The numbers of upregulated genes during the disease stage was much higher than during the asymptomatic stage. This suggested that direct interaction between RABV and target cells induced massive destruction of a cellular homeostasis which may lead to functional termination of the CNS.