The probability of infection by low pathogenic avian influenza (LPAI) through eating contaminated raw poultry meat or raw table eggs is “negligible”, according to estimates from the European Food Safety Authority (EFSA).
EFSA said there is a high level of uncertainty on the transmission pathways for poultry and wild birds due to the limited number of studies. Avian influenza viruses are either high or low pathogenic viruses (HPAI and LPAI). A few of them such as A(H5N1) and A(H7N9) is known to cause severe disease and death in humans.
There is no evidence that avian influenza can be transmitted to humans through eating contaminated poultry. Thorough cooking of poultry meat will destroy the virus. Epidemiological evidence suggests infection in humans occurs rarely and only after very close contact with infected animals.
“It is, therefore, likely that a high dose of the virus may be needed to initiate an infection and that a readily accessible entry route for avian influenza viruses does not exist in humans. The risk of avian influenza virus transmission to humans via food could increase if significantly higher virus titers or a change in virus distribution in poultry tissues were reported,” said EFSA.
The European Commission asked EFSA to assess the risk for transmission of LPAI viruses of subtypes H5 and H7 via raw poultry meat and table eggs to poultry and other captive birds leading to infection and onward virus transmission to animals and humans.
EFSA said the assessment is a qualitative estimation of the theoretical probability of transmission by assessing the biological plausibility of the events to occur and not the actual probability in the EU in 2018.
Raw poultry meat
There are three steps in determining the presence of LPAIV in raw poultry meat or raw table eggs before an individual is exposed: surveillance and ante-mortem inspection of live animals, inspection of meat or table eggs during the food chain and preservation of the virus in these products in the chain, according to the assessment.
The report indicated it was unlikely that a bird with LPAIV in muscle tissue would not be detected via surveillance or ante-mortem inspection in commercial holdings.
An INFOSAN study in 2005 found common preservation processes such as freezing and refrigeration do not substantially reduce the concentration or viability of HPAI viruses in contaminated meat. A 2017 EFSA avian influenza scientific opinion revealed LPAI viruses can also survive for a long period at low temperatures.
There is a lack of data on the proportion and frequency of raw and undercooked poultry meat although it is expected to be rare. Cross-contamination of cooked poultry meat with infected raw meat could modify the probability of exposure.
The combined probability of exposure and subsequent LPAIV infection via raw poultry meat is negligible for humans exposed via consumption based on the low concentration that could be present in raw poultry meat and acid-lability of the virus.
The probability of LPAIV transmission from an individual infected via raw poultry meat is also negligible for commercial poultry and humans.
“With regard to the oral route, it has been considered in this assessment that human exposure can occur by consuming raw poultry meat, but also by consuming undercooked poultry meat or meat cooked at temperatures not suitable for the inactivation of LPAIV present in meat due to consumption habits or due to the lack of temperature control and monitoring during the cooking process,” according to the assessment.
Raw table eggs
The combined probability of exposure and subsequent LPAIV infection via raw table eggs is negligible for commercial poultry and humans based on the assumed low concentration inside the egg and acid-lability of the virus.
The probability of transmission from an individual infected via raw table eggs containing LPAIV is also negligible for commercial poultry and humans.
It is unlikely that a bird laying eggs with LPAIV inside would not be detected via surveillance or ante-mortem inspection in commercial holdings.
The combinations of time–temperature at the maximum values would not be able to influence/reduce the preservation of LPAIV inside a table egg in any steps of the food chain.
There are no data on the proportion of eggs used in meals that include raw eggs in their preparation or are consumed raw, but it is expected to be a very small fraction of the total number of table eggs consumed in the EU, according to the assessment.
High-risk practices include consumption of raw eggs or production of sauces or dishes that require them like Hollandaise sauce, mayonnaise, Caesar salad dressing, deserts (e.g. tiramisu, zabaglione), homemade ice cream or beverages (milkshakes, smoothies, eggnog) but these are increasingly being made with pasteurized eggs. Home cooking is another scenario for exposure to raw table eggs.
“Although the presence of LPAIV in raw poultry meat and table eggs is very unlikely to negligible, there is in general a high level of uncertainty on the estimation of the subsequent probabilities of key steps of the transmission pathways for poultry and wild birds, mainly due to the limited number of studies available, for instance on the viral load required to infect a bird via raw poultry meat or raw table eggs containing LPAIV,” concluded EFSA.
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