Pigs | April 2024
App Actinobacillus pleuropneunomiae (App) is a bacterium that is known to cause pleuropneumonia (inflammation of the pleura and lungs). App can be acute, peracute or chronic, and can also persist subclinically under the correct conditions. Young pigs in particular (including finishers) are more susceptible to clinical infection with App. There are at least 19 known different serogroups of App, with varying combinations of virulence factors that are one determinant of whether clinical symptoms occur. That App is known to be a causative agent can also seen in various monitoring tools, starting with the Online Monitor. In 2023, 70 per cent of App reports were about finisher pigs and 26 per cent about weaned piglets (see figure below).
1,7%
1,6%
26,3% Breeder and finisher pigs Weaned piglets Sows Suckling piglets 70,4%
Figure: Number of reports of App in the Online Monitor, by age category (for 2023)
Over a quarter of all respiratory complaints in the Online Monitor in 2023 were thought to be caused by App. If we look at the total number of health problems reported, App is stated in 8 per cent. No clear increase or decrease has been visible over the past few years. However, more reports of App are made in spring and fewer in autumn. Symptoms such as coughing, nasal discharge and other respiratory complaints, are often attributed to an App infection. App is a regular topic of conversation on the Veekijker phone line. In the second half of 2023, App ranked third among disease-specific topics in terms of the number of questions. Over 2023 as a whole, an average of 8 per cent of disease-specific questions were about App, which is the same as the eight-year average (2016-2023). The questions are mostly about serotyping, treatment of clinical symptoms caused by App, vaccination strategy and the role of App as a primary or secondary pathogen. Pathological examinations have shown us that App plays a role in the cause of death in over 7 per cent of necropsies. In the majority of these necropsies, App was responsible for causing pleuropneumonia, mainly by finishers and to a lesser extent in weaned piglets. In the second half of 2023, infection with App was the fifth most common diagnosis upon pathological examination.