Early Diagnosis of African Swine Fever - Sample Selection and Methods
1. nasal swabs/oral fluids can be monitored for African fever antigens earlier than blood/serum.
2. nasal swabs have advantages over blood and serum in terms of sensitivity and experimental precision;
3. The advantages and disadvantages of nasal swabs versus oral fluids were unknown at the time, and the feedback received favored oral fluids as a more suitable sample for early surveillance.
With the progress of anti-African activities step by step, the author has further understanding of the selection of the above samples, now the respective advantages and disadvantages of blood/serum, oral fluid, anal swab and nasal swab in practice are reported as follows.
I. Blood/serum
1, except for sperm collection boars, other pigs blood collection compared to the above two ways, blood collection is the most physically demanding and the most stimulating to the pig.
2. The possibility of contamination spread due to blood spillage during blood sample collection and the process of bailing, bailing assistants and bailing equipment is also the greatest compared to the above two methods.
3. The biggest drawback of blood samples compared to the goal of tooth extraction is that the virus is detected later than nasal swabs or oral fluids - not suitable for early diagnosis and more unfavorable for tooth extraction.
II. Oral fluid.
1, sample collection is simple, but the premise is that pigs are only able or interested to bite the cotton rope, suspected pigs are likely to be uninterested to bite - the sample representation is not good enough.
2, cotton rope was good pigs, suspected pigs or small strong type a chewing, we hang the cotton rope in turn has become a deep kissing cross-transmission medium
3, oral fluid samples contain a variety of enzymes, if the sample test tube did not add nuclease inhibitors, then the test results are prone to false negatives.
Third, the anal swab
1, easy to sample, but the sampling staff is easy to become a vector, similar to the nasal swab sampling need to use a glove, shoe covers or out of the sterile foot basin to reduce the risk of being a vector.
2, feces with relatively low amount of poison (stomach acid will take out a lot of pathogens) - detection rate is relatively low.
Combining the advantages and disadvantages of the various samples above, combined samples will have greater advantages than single samples, such as the use of oral and nasal swabs, anal and nasal swabs.
For groups requiring frequent repetitive sampling while taking into account the goal of achieving early monitoring, low stress, low contamination or controllable, oral and nasal swabs, anal and nasal swabs combination should be a good choice.
Four, nasal swab.
1, extremely simple to sample pigs at the early stage of disease or suspected pigs - human-pig peace.
2, no abnormal pigs in the first three collection is simple, the matter is not more than three, the fourth or so pigs will put the nostrils against the bar or wall - just do not let you sample.
3、People may enter the pig pen - fattening or nursing, and contact with feces/ excrement, so you need to change disposable shoe covers and gloves to enter and leave the pen, or step into the disinfected foot basin first and wash your hands before you leave the sampling pen area.
