While our focus is decidedly on avian flu these past few weeks, it wasn't very long ago we were following an outbreak of Swine Variant influenza in the upper Midwest (see MMWR: Investigation Into H3N2v Outbreak In Ohio & Michigan - Summer 2016) linked to state and county fairs.
Since the influenza subtypes that commonly circulate in swine (H1, H2 & H3) are also the same as have caused all of the human pandemics going back 130 years (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?), swine influenza viruses are watched carefully for signs of jumping to humans.
This undoubtedly happens far more often than we know, but since swine influenza infections in humans look like human flu, and testing for swine variant viruses is fairly uncommon around the world, we don't often hear about it.
The Netherlands' The National Institute for Public Health - RIVM
is reporting a recent severe infection with an H1N1v (swine variant) virus in a patient with swine exposure.
The patient has now recovered. Direct contacts of the patient were monitored for 10 days, but no signs of transmission were detected. First the report from RIVM, then I'll return with a bit more.
Patient ill by swine flu
Two weeks ago in a patient with severe flu symptoms by the laboratory found that this is caused by a swine flu virus. This type of flu virus (Influenza A (H1N1)) has been coming for decades in pigs in Netherlands where the mild complaints. It is now found in a patient. Previously this infection in 1986 and 1993 in humans. That this occurs more frequently is not excluded.
The patient was recently in a stable with swine. Influenza of animal origin is a notifiable disease in people. As a precaution, the direct contacts of the patient 10 days followed and investigated if they received complaints that can fit (mild) flu. From this monitoring research of the public health service found that there are no other people have been infected with this swine flu virus. The patient has since been restored.
This infection with the swine flu virus has no connection with the avian flu virus (H5N8) that recently at water birds is found.
Flu virus in animals
There are several types of flu viruses. Some virus types occur mainly in people for, while other more in animals, such as swine flu and bird flu. These different variants of flu virus spread mainly within their own species. In rare cases, an animal flu virus to humans. The virus is then generally not or only very limited transferred to other people.
Disease symptoms in humans
The disease symptoms after infection with an animal flu virus similar to those of the flu in people. The complaints are generally mild: fever, nasal stuffiness, colds, sore throat, cough, headache and muscle pain. Sometimes the complaints expired with for example a more serious pneumonia.
In addition to scattered cases in the United States, we've recently seen reports of swine variant infections in both Brazil and China. The WHO's most recent Risk assessment for swine flu reads:
1. What is the likelihood that additional human cases of infection with swine influenza viruses will occur? Influenza A(H1N2) and A(H3N2) viruses circulate in swine populations in many regions of the world. Depending on geographic location, the genetic characteristics of these viruses differ. Most human cases are exposed to swine influenza viruses through contact with infected swine or contaminated environments. Human infection tends to result in mild clinical illness. Since these viruses continue to be detected in swine populations, further human cases can be expected.
2. What is the likelihood of human-to-human transmission of swine influenza viruses? No case clusters have been reported. Current evidence suggests that these viruses have not acquired the ability of sustained transmission among humans, thus the likelihood is low.
3. What is the risk of international spread of swine influenza viruses by travellers? Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as these viruses have not acquired the ability to transmit easily among humans.