Comparison of non-fever detection samples: oral and nasal swabs & oral fluids & nasal and anal swabs
Unlike European countries where the action of complete extermination of the source is different, major domestic pig organizations and institutions engaged in professional technical services have established and implemented the strategy of tooth extraction in the face of NHF. The long term impact of this strategy is right or wrong regardless, for practitioners in the snow and wind, how to stop the bleeding and even survival is the immediate priority.
The success of tooth extraction is inextricably linked to the setting of the program, the layout of the hardware, the daily rehearsals, the flexibility of the decision makers and the details on the ground. The important foundation of the above activities is to know where that enemy who does not act quickly is, and we continue to communicate about the selection of an appropriate early monitoring sample.
Regarding sample selection for early diagnosis, the author has described in "Early diagnosis of African swine fever - sample selection and methods".
1. the advantage of nasal swabs over blood and serum in terms of sensitivity and experimental precision.
2. nasal swabs/oral fluids can be monitored for non-fever antigens earlier than blood/serum.
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, the author has further understanding on the selection of the above samples and now reports the advantages and disadvantages of nasal swab, oral fluid and blood/serum in practice.
Nasal swab.
1, sampling of pigs at the early stage of disease or suspected pigs is extremely simple - human pigs are at peace with each other.
2, no abnormal pigs in the first three collection is simple, but only three things, the fourth or so pigs will put the nostrils against the bar or wall - just do not let you sample.
3, personnel may enter the pig pen - fattening or nursing, and contact with feces/excretions, etc., 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 leaving the sampling pen area.
Oral fluids.
1, sample collection is simple, but the premise is that pigs are 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 by good pigs, suspected pigs or small strong type of a chewing, we are hanging 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 include nuclease inhibitors, then the test results are prone to false negatives.
Blood/serum
1, except for sperm collection boars, blood collection from other pigs is the most physically demanding and the most stimulating for pigs compared to the above two methods.
2、The possibility of contamination transmission due to blood spillage during blood sample collection as well as the preservation process, preservation assistants and preservation equipment is also the highest compared to the above two methods.
3. The biggest drawback of blood samples is that the virus is detected later than nasal swabs or oral fluids compared to the target of tooth extraction - not suitable for early diagnosis and not conducive to tooth extraction.
Anal swab
1, easy to sample, but the sampler can easily become a vector, similar to nasal swab sampling requires the use of gloves, shoe covers or disinfected foot basin at the exit to reduce the risk of being a vector.
2, fecal carriage of toxins is relatively low (stomach acid will take out a lot of pathogens) - detection rate is relatively low.
