The Chikungunya Virus Epidemic in La Réunion
How France’s national blood authority, EFS, acted quickly to protect the safety of platelets during an epidemic.
Pandemic Preparedness is Essential to Protect the National BloodSupply
Even in countries with the most advanced blood systems, the blood supply remains vulnerable to new infectious diseases. Each year brings a new threat from diseases such as Avian flu, West Nile, Dengue Fever or the current Chikungunya virus crisis in the Indian subcontinent. The Etablissement Français du Sang, or EFS, which is in charge of blood collection and preparation in France, must constantly monitor the worldwide incidence of infections. During a pandemic of a blood-borne disease, when large numbers of people become infected at once, it is especially difficult to maintain the supply of safe blood products. Recent experience in the overseas department of La Réunion during the Chikungunya virus epidemic demonstrates the difficulties faced by local blood authorities during a national health emergency.
Viruses Spread Across Borders Quickly
Today, deadly viruses can move easily to Europe as travelers return from infected areas. Though some individuals will become ill, many more may experience few or no symptoms, and never recognize that they have been infected. Also, these diseases are spread by migrating animals such as birds, or even mosquitoes trapped inside imported flowers and bamboo plants.
Unfortunately, these new threats can be difficult to recognize when they first appear as there may be no existing tests, and infected blood may slip into the blood supply. French blood donors must pass a detailed medical history questionnaire and are then tested to ensure they are free of particular infections such as HIV and hepatitis. To achieve an even higher level of safety, the EFS has evaluated a newer type of technology called pathogen inactivation, or PI. PI treatment can kill harmful organisms such as viruses and bacteria, similar in concept to routine pasteurization of milk and other dairy products. When PI is in use, infectious threats can be neutralized even before infected donors are identified.
Chikungunya Virus Epidemic in La Réunion: Impact on the Local Blood Supply
In late 2005, the EFS faced an unexpected challenge to the national blood supply when La Réunion became the epicenter of an explosive regional outbreak of Chikungunya virus. Spread by the bite of infected mosquitoes, the disease causes flu-like symptoms including severe headache, fever, nausea, and joint pain. In fact, the curious name is Swahili for ‘that which bends up’ because of the stooped posture of victims suffering from sore joints. In contrast to earlier epidemics, in this outbreak the Chikungunya virus had undergone genetic changes and become more infectious and caused more serious disease such as bleeding, hepatitis, meningitis and fetal infection. The death rate from this infection was estimated to be 1 per 1,000 infected patients.
By April 2006, this island in the Indian Ocean had an epidemic, with over 250,000 infections out of a total population of approximately 750,000. With one in three inhabitants already infected, and the remaining two-thirds at risk, EFS officials concluded that local blood donors were not safe (i.e., free of Chikungunya virus) without significant changes to standard blood collection and processing. Though implementation of new donor screening questions has often been used as a first line of response during epidemics, this simple precaution was not an option for La Réunion’s blood centers.
For two blood components, plasma and red blood cells, temporarily importing units from metropolitan France was the most practical solution, but the third blood component, platelets, could not be imported because of the transportation time.
Making Local Blood Safe: A New Pathogen Inactivation technology for Platelets
The INTERCEPT Blood System is designed to inactivate most harmful pathogens, including emerging viruses such as West Nile and Dengue fever, as well as parasites that cause malaria and Chagas’ disease. In addition, the treatment also inactivates white blood cells and bacteria present in donated blood, which can be harmful to the blood recipient.
The EFS made a rapid decision to implement INTERCEPT in La Réunion to avoid critical shortages of platelets. Even though the process was not yet widely used in France, the process has been extensively studied by EFS Alsace under the direction of Prof. J.P. Cazenave, and personnel from Strasbourg traveled immediately to La Réunion to ensure that installation and training were successful.
Since then, the system has been used to treat over 1,500 units of platelets that otherwise might not have been available to the island hospitals.
Chikungunya Virus Spreads to Europe
Chikungunya cases have now been identified in six European countries, including over 700 cases in France. These infections were diagnosed in travelers returning from the Indian Ocean, a popular tourist destination. Eurostat estimates that in 2004, over 1.4 million people traveled from Madagascar, Mauritius, Mayotte, La Réunion and Seychelles to the European mainland.
With the recognition that infections were being imported came concern about the possibility of a local Chikungunya epidemic within Europe. The Asian tiger mosquito that spreads the disease, Aedes albopictus, has been found in a number of areas including the South of France and Corsica.
At a March 2006 meeting in Stockholm, the European Centre for Disease Prevention and Control concluded that there is a risk for Chikungunya transmission in Europe, though the risk is difficult to determine and would probably be limited to certain regions. The group of experts also stressed the need to broaden the risk assessment to vector-borne diseases in general like West Nile and Dengue fever.
A Role for Pathogen Inactivation in Routine Blood Safety
European blood centers need a method that can kill harmful organisms in donated blood so that viruses and parasites can be prevented from infecting blood recipients. Since August 2006, EFS Alsace, under the direction of Prof. Cazenave, a leading blood expert and member of the Académie Nationale de Médecine, has treated 100% of its platelet supply with the INTERCEPT system with no impact on daily operations or the supply of platelets. In fact, treating physicians in the hospitals supplied by EFS Alsace have observed a reduced number of acute transfusion reactions after using these treated platelets.
Prof. Cazenave says: “We know that there is a risk for a pandemic to strike Europe, but we won’t know what infection, where or when until it is already happening. It might not be Chikungunya, but it could be Avian influenza, it could be something else. We know our patients will continue to need transfusions. The challenge for blood centers is to plan for how we can continue to supply safe blood during a national health emergency like an epidemic.”
“But pathogen inactivation is critical to blood safety at all times, not just during an epidemic. We already use pathogen inactivation treatment for France’s plasma. However, for platelets and red blood cells, we currently rely on a range of other tests to detect a limited number of diseases. We can decide to add additional tests only when we know the problem. However, we will never be able to test for all the things that might be in each blood donation. Pathogen inactivation treatment inactivates the widest spectrum of infections from viruses, parasites and bacteria.”