app注册送18Shape 安博电竞登录Shape 齐发国际下载author 龙都国际娱appShape 广东11选5chevron 291棋牌app下载cross 博华网址Shape 百姓彩票开户Shape 二八杠金口诀Shape 八方平台appGroup 澳门满亿娱乐官网hamburger 牛牛娱乐apphome 大富贵彩票APPGroup 星球娱乐网站magnify MG老虎机网上Shape 足球比分007Shape 雪缘园足彩Shape opebet体育apprss 皇冠体彩吧Shape

Yellowhead Disease

What is it?

Yellowhead disease is a viral infection of shrimp and prawn. The disease was first reported in Thailand in 1990 and has since been reported in Asia and America.

Yellowhead is a positive-sense, single-stranded RNA (ssRNA) virus, originally thought to be related to rhabdoviruses but now known to be related to coronaviruses and arteriviruses.

Yellowhead disease has now been formally classified in the new genus Okavirus and new family Roniviridae within the viral order Nidovirales .

Where and When Might it Occur?

LOLS10在线直播下注The appearence of the disease and mortality often occur within two to four days following an interval of exceptionally high feeding activity that ended in abrupt cessation of feeding.


Yellowhead disease can be identified by high and rapid mortality in mainly early to late juvenile stages.

The yellowing of the cephalothorax, bleaching of body colour and congregation at pond edges is also often seen.

Histologically, moribund shrimp show systemic necrosis of cells of ectodermal and mesodermal origin, with the formation of intensely basophilic cytoplasmic inclusions ( by haematoxylin and eosin staining ) that arise from phagocytosed nuclei and viral inclusions. However, gross signs of infection and histopathology are not entirely reliable indicators of YHD and the use of molecular methods for confirmatory diagnosis required.

LOLS10在线直播下注 Confirmation of yellowhead disease requires more detailed analysis by RT-PCR, Western-blot analysis, in-situ nucleic acid hybridisation and TEM.


No effective vaccination methods have been developed so far.

Source: Cefas and OIE