拟穴青蟹(Scylla paramamosain)血卵涡鞭虫病的流行病学分析

为解析拟穴青蟹(Scylla paramamosain)血卵涡鞭虫病的流行病学特征,于2012年4—11月采用跟踪监测和实地调查的方法,结合病原分离鉴定及病蟹的病理学观察,统计分析了浙江省温州地区养殖拟穴青蟹血卵涡鞭虫病的流行情况。结果表明,患病拟穴青蟹的肝胰腺、肌肉、鳃等组织病理显示有大量血卵涡鞭虫侵染,并能用PCR方法快速检出。温州地区养殖拟穴青蟹血卵涡鞭虫病在每年5—11月均有发生,7—9月为集中发病时间,死亡高峰出现于8—9月之间,年份间(2010—2012)与发病率无相关性,而不同月份对病害的发生有极显著影响(P0.01)。不同发育阶段以脱壳期的发病率相对较高,发病蟹的规格主要以50g以下的幼蟹和250g以上的成蟹为主。拟穴青蟹血卵涡鞭虫病的发生与水温(r=0.756)和盐度(r=0.631)变化关系较密切,夏、秋季节受梅雨、台风影响而引起水温和盐度的剧烈变化可能是暴发血卵涡鞭虫病的诱发因素。

EPIDEMIOLOGY ANALYSIS OF HEMATODINIUM sp. DISEASE IN SCYLLA PARAMAMOSAIN

This study reports clinical and epidemiological characteristics of Hematodinium sp. infection in swimming crab Scylla paramamosain populations in Wenzhou, China, between April and November in three years (2010-2013). The infection in the crabs was detected by both species-specific PCR and microscopic examination. Epidemiological data show that the infection occurred between May and November, and the prevalence of infection was higher in summer time and peaked in August. The prevalence was positively correlated with temperature (r = 0.756) and salinity (r = 0.631). This trend was similar year to year. In addition, our data show that the infections occurred in all sizes and life stages of the crabs. Juvenile crabs in body weights <50g and adults >250g, and moult-stage crabs were found more susceptible to Hematodinium sp. infection. The study suggests risk of Hematodinium sp. infection in swimming crab is high in hot months as heavy rain or tropical storm may result in sharp changes in water temperature and salinity, to which preventative measure shall be made.