Criteria for a Good Disinfectant

What are the criteria for a good disinfectant?

Composition: how many groups of disinfectants are combined within the product? And : is there a synergy between the different groups? As an example, quaternary ammonia compounds or QAC will work in synergy with aldehydes and significantly increase the efficacy. The QAC will allow the aldehyde to penetrate better in order to do their work (kill) in every crack , pore or microscopic hole. The QAC alone would not kill naked viruses nor spore bacteria. The aldehyde alone would have penetration difficulties. Together, they can do the whole job. (Combining single chain QAC with double chain QAC even enlarges their spectrum!). Finally, the product should carry buffering agents (preventing chemical incompatibilities) , stabilisers (in Europe, the shelf life should be on the label by means of an expiration date) , sequestering agents (allowing to work in hard water) and wetting agents (allowing to work in presence of organic matter). Last but not least the disinfectant should have a certain residual effect (preventing early re-contamination).

• Efficacy: bactericide, funghicide and virocide. This means you need a disinfectant (a -cide, not a -static !) that KILLS all bacteria, funghi , viruses and spores and leaves no room for acquiring resistance (or you will need to rotate). The disinfectant should equally do this job in presence of organic material. The AOAC standard testings are done with 5% organic matter and in 400 ppm hard water. Check if the label claims hard to kill viruses such as PCV2. For North America, an EPA claim for PRRS is advised.
• Versatility: ideally, the disinfectant should be ready to use for spraying, foaming (requiring a foam lance) and fogging (it should include the right carriers for hot or cold fogging).
• Safety: for people, animals and equipment. The latter means it should NOT be corrosive. To be safe for the environment, it should also be bio-degradable and hence not contain any heavy metals (like tin ).
• Cost efficient: this is not the cost per gal or Litre, but the cost DILUTED i.e; the cost / Litre x the dilution. The dilution is determined by the presence of active ingredients. Always check how many grams / Litre, oz/gal or % active ingredients the disinfectant contains !
• Stocking density: there are standards for stocking densities. Overshooting them may result in lower growth, more disease pressure and abnormal behaviour (cannibalism). Also the climate will determine the density.
• Prevention and extermination of rodents and insects: rodents don't only harm your farm (like eating insulation), they also contaminate the feed and spread diseases like Leptospirosis, Salmonella, Dysentry,
• Blood sucking and biting insects also spread diseases. Manure and wet feed leftovers are the ideal breeding ground for flies.