Koi Carp disease in Indonesia - Intervet helps out!

18 March 2003

Intervet Participation in an Investigation of a Serious Disease Outbreak of Koi and Common Carp in Indonesia

A serious disease outbreak in Koi carp (Cyprinus carpio koi, an ornamental fish) and common carp (Cyprinus carpio carpio, a food fish) occurred early this year in Indonesia.  The disease started in the area of Blitar in East Java in April 2002, then spread rapidly throughout Java Island, causing very high mortality (80-90%) in both common and Koi carp.  The loss is estimated to be 50 to 80 billion Rupiahs (approximately 5 to 8 million USD).

Clinical signs in infected fish include severe gill necrosis, increased mucus production, superficial haemorrhages, fin rot and enlargement of the kidney and liver with haemorrhages and discolouration. Indonesia has not experienced a disease of this nature in the past. It was suspected that the disease was introduced through importation of koi carp from another country.

At the request of the government of Indonesia, the Network of Aquaculture Centers in Asia Pacific (NACA) organized an Emergency Disease Control Task Force Team (Task Force) to assist the local fish health authority to identify the problem and to find control measures for the disease.  The Task Force visited outbreak farms and took clinical specimens for laboratory testing.

In response to the call from NACA, Intervet participated in the investigation.  With assistance from our local company, Intervet Indonesia, we received a number of samples of both koi and common carp from the Task Force in mid-July. In the weeks that followed, Intervet Singapore and colleagues in pathology and virology at Intervet International worked very hard on the diagnosis testing.  Various methods were employed to search for the causative agent: polymerase chain reaction (PCR), in vivo passage through koi carp, virus isolation in cell lines and electron microscope examination. The Intervet team, led by Dr. Ellen Ho in Singapore, worked closely with scientists from other institutes and universities, such as the Aquatic Animal Health Research Institute in Thailand, the University of California at Davis, and the Institute of Aquaculture at the University of Stirling. Based on the detection of koi herpesvirus (KHV) by PCR, KHV might have played a role in the disease outbreak. Other agents such as parasites and bacteria might be also involved.  The Task Force has classified the outbreak as “Mass mortality of koi and common carp” until a clear association with KHV or any other specific disease can be established. 

Intervet’s active involvement in this joint investigation has been highly appreciated. A letter from Mr. Pedro Bueno, Director General of NACA, states that “NACA is pleased to acknowledge officially and express gratitude to Intervet for its participation and contribution to the Emergency Disease Control Task Force on a Serious Disease of Koi and Common Carp in Indonesia… We appreciate very much the valuable expert assistance, and your personal and keen interest, to this work and look forward to more cooperation in the future.”

Authors note:
Koi herpesvirus is a herpesvirus that is distinctly different from Herpes cyprini, the most commonly known herpesvirus in cyprinid fish.  KHV has only been identified as a pathogen of Koi and common carp since 1998.  It was found in the UK, continental Europe, the USA and Israel.  Most mortalities occur at water temperatures of 22-27°C, being very much reduced below this and there being virtually no occurrence at 30°C or above. Mortalities are very rapid and severe.  In many cases, 80-100% mortality occurs within 10 days of disease outbreak. Diagnosis is typically based on clinical observation, PCR, virus isolation, histopathology and electron microscope examination. While biosecurity measures will help, there is no effective treatment for KHV at present.

Sources of information:
NACA Newsletter. April-June 2002.
NACA Emergency Disease Control Task Force Report – Outbreak of Disease in Koi and Common Carp in Indonesia, November, 2002
OIE, 28 June 2002. Disease Information. Vol. 15, No. 26. 
Ornamental Aquatic Trade Association. Koi Herpes Virus (KHV). December 2001.