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Scientists comment on a case of human-to-human case of Swine Flu reported in Spain.
Prof Ian Brown, Group Leader, Pirbright Institute, said:
“Swine influenza viruses do occasionally spillover to humans and it is not uncommon for direct links to pigs being inapparent. Detailed epidemiological enquiries will be required including a full traceability of the recent contacts of the infected person before any conclusions can be drawn on true origin and importantly onward transmission risk to other people. In general these viruses lack the capability to efficiently transmit amongst humans but genomic data when available could offer insights as to why this event happened. It should be noted elderly persons may be more vulnerable to infection especially if they have underlying conditions. The situation needs careful and urgent monitoring but without more information it would be premature to consider the risk level in Spain and wider Europe has changed.”
(from SMC Spain) María Iglesias-Caballero, Virologist at the Reference Laboratory for Influenza and Respiratory Viruses of the National Microbiology Centre – Carlos III Health Institute, said:
“We have requested serum from this patient because sometimes, as we use very sensitive diagnostic techniques, the cases are not always true infections. Serum has been requested to confirm this. That is pending.
“The samples we have available have been sent to a WHO centre and to the Centre for Research and Innovation in Catalonia (CRIC), so everything is perfectly coordinated within the network. It is true that this is a peculiar case, but it is under control. Catalonia is one of the autonomous communities that does very well in surveillance, sequencing a lot, and this is the only case we have.
“So we believe that if there really were sustained circulation, we would have detected it, and that is not the case. But even so, what we can seriously attest to is that we are monitoring it. We have coordination from the autonomous community, central government, Europe and internationally.”
(from SMC Spain) Aitor Nogales González, Senior scientist at the CSIC at the Animal Health Research Centre (CISA), National Institute for Agricultural and Food Research and Technology (INIA), said:
“It is not unusual for a swine flu virus to infect humans. Many cases go undetected because there is no epidemiological surveillance in this regard, while others go unnoticed because they are asymptomatic or because specific tests are not performed. These infections are usually mild or even asymptomatic, or cause symptoms similar to those of common flu, and are not usually transmitted between humans, or do so with very low efficiency.
“The virus responsible for the 2009 pandemic, the last influenza pandemic to date, was particularly complex, combining genetic segments from swine, avian and human influenza. Its origin was traced and it was confirmed that the jump to humans came from pigs. However, it was a virus that had been recombining and evolving for years before emerging massively in humans.
“In contrast, in the current case, pending final confirmation of the analyses and genetic sequences, the available data suggest that it is one of the swine flu variants circulating today. There is no indication, for now, that we are dealing with a particularly novel virus or one that behaves differently than expected. Therefore, the risk to the human population is considered low or very low.”
(from SMC Spain) María Montoya, Researcher in the Viral Immunology: Therapies and Vaccines group at the Margarita Salas Biological Research Center, said:
“I’m not surprised. Often, when flu is circulating, if there are no symptoms, it is not analysed in detail unless there are complications or someone goes to hospital and is tested. The fact that the patient has not had contact with animals means that they have been infected through contact with another person, who in turn may have had contact with animals or with another person in contact with animals. The thing is, flu viruses can be dangerous, they can recombine, as happened with the first pandemic of the 21st century. In addition, there may be a serious health problem in people who have a weak immune system for various reasons, both congenital and due to illness. The fact that it has been detected makes us appreciate the importance of detecting viruses that are circulating in Spain, because with this information we can be better prepared for possible complications later on.”
Declared interests
Prof Ian Brown: IB receives research funding to study avian influenza in multiple hosts. IB is a member of the UK scientific committee ‘New and Emerging Respiratory Threats Assessment Group’. IB participates in UKHSA led fora that assess the risk to human health from avian influenza viruses.
For these experts, no reply to the request for DOIs was received.