News

The rapid detection of Hepatitis A virus in shellfish is becoming a reality in SEAFOODplus

By: Rosa M. Pintó, M. Isabel Costafreda and Albert Bosch

June 20. 2005

Rapid quantitative detection of pathogenic viruses in shellfish is necessary for preventing diseases, but has not been possible due to lack of reliable methods. SEAFOODplus is developing the needed methods.

Hepatitis A virus (HAV) is responsible for around half of the total number of hepatitis diagnosed worldwide and is transmitted by the faecal-oral route. As a consequence of globalization, transnational outbreaks of hepatitis A are reported with increasing frequency. Some of these outbreaks are shellfish borne.

An outbreak of hepatitis A affecting 184 people from the Valencia community, Spain, was caused in 1999 by the consumption of Peruvian coquina clams complying with EU shellfish standards. The median age of the patients was 24.6 years (range 3 – 57), and 70% of the cases occurred in individuals 20 – 34 years old.

The detection of HAV has been possible for some time both in clinical and shellfish samples by a standard reverse transcription-polymerase chain reaction (RT-PCR) procedure. However virus quantification was not possible at the time of the outbreak described above. Developments in Project 3.1 REFHEPA within SEAFOODplus will now enable the enumeration of viral genomes through real-time RT-PCR techniques.

Using this newly developed technique, it has been demonstrated that virus levels in HAV-positive frozen coquina clams related with the outbreak described ranged from 5x10²/g to 5x10⁴/g of hepatopancreatic tissue as shown on the table below.

The further standardization of real-time RT- PCR procedures now being pursued in SEAFOODplus will enable their use in a routine diagnostic context to increase the safety of shellfish delivered to the consumer.