From the sanitary point of view, businesses have also improved the health of the herds by focusing mainly on the control of three diseases and in the improvement of the biosecurity programmes. The viral diseases that are considered to have most impact in the North American industry are porcine circovirus (PCVAD), porcine respiratory and reproductive syndrome (PRRS) and the swine influenza virus (SIV).
In the last three years the USA has suffered an epidemic of wasting which has been partly associated with the introduction of new strains of porcine circovirus. This epidemic was first characterised by a significant increase in mortality in animals of over ten weeks old and also in an increase in pigs with poor body condition. Fortunately for the country the presence of the epidemic coincided with the launch of the first commercial vaccines for porcine circovirus type 2 in growing pigs. These vaccines have surpassed all expectations and their effect is reflected in the improvement of productive parameters at a national level where the expectations of the census on finishing pigs were surpassed by 4% during winter 2007. The vaccines have improved not only the mortality parameters but also the growth parameters in populations that were affected subclinically. The subclinical role of the circovirus type 2 was not appreciated until the vaccine started to be used extensively. Nowadays the circovirus vaccine in growing animals is considered to be an essential tool for the producer and its use has become a normal part of vaccination programmes.
PRRS is without doubt the disease that has the biggest economic impact in the USA. Producers and veterinarians have learnt to manage the disease, and a good production can generally be obtained even when the disease is present. However, lateral infections that are often caused by new strains continue to make it difficult to predict production as it is difficult to predict the virulence of these new strains. Many farms particularly in the Midwest zone, suffered severe outbreaks in the winter of 2007/08. In most cases they were new strains for the farms in question. The strains involved in the outbreaks, which cause the greatest number of miscarriages and important increases in mortality in sows, newly born piglets and weaned pigs, appear to be related to each other and are considered to have high virulence and transmissibility. As a result of this, the producers are seriously considering adapting air filter technology in sites 1, Of course this is not cheap but it is considered to be worth it given the cost of an outbreak of PRRS. Air filter technology is already working effectively in many insemination centres and the challenge is now to adapt this technology to sites 1. Furthermore, there is more and more conclusive information on how easily the PRRS virus moves through the air, and it has been detected in samples of air at distances of over 3km (Dee, 2008, recent studies).
The swine influenza virus has also become more important in recent years. Since 1999 a change has been observed in the epidemiology of this disease with the appearance of new subtypes of the virus with highly varying strains which contain genes not only of a porcine origin but also from avian and human origins. There are various subtypes that have appeared including the new variants H1N1, H3N2, H1N2 and most recently H2N3. Many of the infections associated with these new types of influenza are considered to be severe and can cause death both in sows and in growing animals. Commercial vaccines have not been very effective due in part to the challenge involved in fighting against the high number of new subtypes and strains. The subject of influenza is in itself a sensitive issue due to the implications it has for public health.
Furthermore, in the last few years producers have invested substantial sums of money in improving the biosecurity of their systems. Many daily biosecurity practices have been improved and significant sums have been put into transport and personal training. Despite all this investment, the appearance of diseases has not been totally stopped, so now more drastic measures are being considered such as the implementation of filters in sites 1.
Without a doubt, the USA is betting on swine production and looking at the exports market, so the sanitary state and the profitability of the industry are two key points to maintain in the future.
- Recent update on swine health in Asian swine industries 01-Feb-2010 (8 years 10 months 10 days ago)
PRRS: Transmission via indirect routes (2/2)23-Dec-2008 9 years 11 months 18 days ago
PRRS: Transmission via direct and indirect routes (1/2)26-Nov-2008 10 years 15 days ago
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19-Jul-2010Dinesh BogatiThe burning topic of swine flu has threaten all the farmers not only in USA but also in all over the world. To escape from health hazard all the farmer must be trained such as critical care jobs for the betterment of farmers and all the domestic animals.