What are the symptoms of African classical swine fever? How to detect which pig is sick?

Speaking of African classical swine fever, everyone is no stranger to it now, because it has been more than 10 months since it was first introduced into China in August last year, and now all farmers have some understanding of it. What are the symptoms of African classical swine fever? How to detect which pig is sick?

What are the symptoms of African classical swine fever?

African classical swine fever is a malignant infectious disease with high fever, high resistance and high mortality. Once the disease occurs in the farms involved, the highest mortality rate of pigs will reach 100%, so it poses a great threat to farmers. As there is no effective treatment vaccine, once the disease in the farm basically no remedial measures, can only go into the maximum possible to reduce the loss, then it is particularly important to detect abnormalities in advance.

The spread of African classical swine fever virus is generally divided into three stages. the first stage is the incubation period. after the virus spreads into the farm and comes into contact with pigs, it will not get sick immediately, and it is no different from normal pigs. The incubation period is usually 3 to 7 days, and then enter the second stage.

The second stage is the onset period, which begins with a high fever, followed by anorexia, laziness and weakness, and purplish-red plaques on the body, which is usually about 3 to 4 days, and then enters the third stage.

The third stage is the pig death stage, before the pig death, the cyanosis (purple) area is further expanded, especially behind the ear, abdomen and back, and the body temperature will drop before death, which is the biggest difference from other similar diseases.

Second, how to detect which pig is sick?

1. If you are testing in a whole group, of course it is the most accurate, and you can clearly know which one is infected or not. But pay attention to one problem, when the whole group sampling, there is a greater chance of cross-infection, must be careful not to reuse the tool, personnel do not cross touch the pig, especially the mouth and nose. But in fact, it is more difficult to achieve complete non-crossover.

2. If you are checking some pigs (and avoid crossing in the process), there are three principles recommended:

① smokes pigs with poor health.

The ② pig house is near the door and the wall (pigs that are easy to contact with the outside world, such as places where people come in and out frequently, places where rats are more frequented, etc.)

③ sampling part of each small area (compared to a material trough can be regarded as a small area)

3. Note that if the test results are negative, but show related symptoms every 4-5 days or so, it may be because the test is just infected, the virus content in the body is low, and the test is insensitive. These conditions need to be re-examined. (it is also possible to eliminate the pig according to suspected cases without testing, because in the event of infection, these testing processes increase the risk of transmission. The operation process of elimination should be sterilized throughout the process)

4. The common types of samples that we can detect.

(1) if you are an etiological test sample (test antigen), then draw porcine auricular vein or anterior vena cava anticoagulant blood, it is recommended to collect anterior vena cava blood, good operation. Total 5ml (stored with EDTA anticoagulant tube).

(2) if it is a serological test sample (detection of antibody), then the pigs with different course of disease should be collected and marked respectively to avoid sample confusion affecting the experimental results. Such as anticoagulant blood collection, aseptic blood collection 3~5mL, room temperature for 12 hours, collect serum, put a sterilized penicillin vial or sample tube, seal, mark and submit for examination.

5. Collection methods of other samples:

(1) Collection of nasal juice: the secretion on the nasal mucosa was dipped with a sterilized cotton swab and placed in a sterilized test tube.

(2) Collection of spleen, lymph node, liver, lung and other parenchyma organs: spleen is the preferred organ, followed by lymph nodes. The spleen and lymph nodes with pathological changes or no obvious changes seen by the naked eye should be within the range of collecting samples. Tissue samples with a diameter of about 1cm were cut off by aseptic operation and added to PBS solution containing 100 μ g / mL penicillin and streptomycin. 4 ℃ was stored and transported for inspection.

(3) in addition, diseased pig feces, dead piglets, aborted fetuses and ticks can also be submitted for examination.

Generally speaking, pigs with African swine fever are easily confused with other diseases if they are not carefully identified. through clinical anatomy, it is found that African swine fever is similar to blue ear disease and acute classical swine fever. Other pig diseases can be easily identified by dissection of diseased pigs.