20 diseased crabs (Eriocheir sinensis) with the classical symptom of HPND and obvious hydrops in inner cavity of the diseased crab were collected on October 2015 from Yangcheng Lake Modern Agriculture Development Company, Suzhou, China.
It had been reported that the hepatopancreas colour of HPND caused by infection of microsporidian Hepatospora eriocheir changed from golden yellow, light yellow to almost white from light to heavy infection.
The epidemiological investigation of HPND was carried out, 10% to 20% mortality rate occurred on most of farms by investigating famers in Suzhou city.
Healthy crabs were fed with the sampled diseased crabs for 30 days, or injected with the filtered fluid prepared from hepatopancreas homogenate of the diseased crabs followed by raising for 30 days, there was no sign or symptom of HPND in the treated crabs, suggesting that the diseased crabs sampled from the farms were not infected by virus or microsporidian.
The results of raising crabs with different pH values of water showed that no death and no symptoms of HPND in crabs were found in the crabs raised in the water of pH 8.0- pH 9.0, the mortality rate of crabs raised in the water of pH 9.5 reached to 40% (P<0.01) while at pH 10 all the crabs were died (Figure 6).
No death and no symptoms of HPND in crabs were found after 20 days by raising in water with different concentrations of avermectin (diluted 10, 100 and 1000 times of working concentration according to manufacturer's instructions), however, a little toxic and side effects of avermectin were appeared on the crabs.
sinensis hepatopancreas albinism was often occurred in some farms of Suzhou city, the symptoms of the diseased crab was very similar with HPND, electron microscope observation showed that no pathogens were found in tissues or cells of diseased crabs, which indicated that E.
But crabs with symptom of hepatopancreas necrosis were not found when crabs were raised in water with different concentrate of avermectin, suggesting that HPND of crab might be induced by water of high pH value.