| Rabies, caused by rabies virus (RABV), is a zoonotic disease that causes acute inflammation of the brain in warm-blooded animals and humans with 100% mortality. The majority of death occurs in Asia, with 95% of human cases found in India and China. In China, rabies raised a severe issue in public health for its increasing number of cases each year. To make the situation worse, little animal rabies data is available. To identify the virus carrier rate of domestic dogs and provide reliable date for making an appropriate surveillance measure of animal rabies, we investigate animal rabies over a period of 11 years on national level in China.(1) Animal rabies surveillanceThis study is a retrospective survey on rabies cases from 2004 to 2014, which involved 17 provinces and municipalities.Collected and received the animal samples including:(i) Brain samples of suspected rabies animals (ii) Dog brain tissue and saliva samples collected randomly from serious rabies epidemic provinces. Analyzed the status and characteristics of animal rabies according to these accumulated data from 2004 to 2014 was used in this study.An average of 76.92%(the numbers of positive samples/the numbers of submitted samples,100/130) animals brain tissue samples from suspected animal were rabies virus positive confirmed by both FAT and RT-nPCR.9454 dogs from 7 provinces without clinic symptom have been tested since 2004, mean infection rate of rabies was 0.33%(CI 0.2-0.5%). Analysis of the results of the two groups (suspected animals and random collected dogs) showed that epidemiological data obtained from monitoring random collected dogs was less informative in comparison with that obtained from monitoring rabies-suspected animals. Saliva of domestic dogs has been used for rabies surveillance in China for years because this method is easy to operation. Our laboratory have received and tested dog saliva samples in rural area since 2007 to investigate the positive rate of the saliva from apparent health dogs. The result showed that the positive rate of saliva samples were 0.21%(CI 0.1～ 0.3%).However, the evaluation of healthy-looking dogs’ virus carrier rate in saliva cannot reflect the rabies epidemic situation.(2) Molecular epidemiological study of RABVTo further characterize the variation of rabies virus, reverse transcription polymerase chain reaction was performed on RABV street strains for the complete N gene and G gene.4 clades of strains were made in this study as in the earlier study, marking Asian 1, Asian 2, Arctic-related and Comopolitan strains. Asian 1 clade consists of isolates from 22 provinces of China. Asian 2 clade is mainly comprises isolates from 12 provinces. Arctic-related clade mainly isolated from the raccoon dogs and dogs in Inner Mongolia. Comopolitan clade consists of isolates from different area of China. Sequence comparison and phylogenetic analysis from the origin of brain tissues showed that steppe-type viruses, closely related to strains reported in Russia and Mongolia. None had been identified previously in China. The viruses from Xinjiang and Inner Mongolia clustered separately into two lineages showing their different geographical distribution.Conclusions:(1) It is the first investigation on the animal rabies on country level in China.(2) Investigated the characterization and circulating of steppe-type RABV in China.(3) The investigation indicates Arctic-related clade had been spread from the raccoon dogs to the dogs.(4) National Agriculture Ministry revised a new version of rabies surveillance strategy according to this study. This new strategy focuses on the suspected animals rather than the pathogenetic animals. |
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