desinfection part 2

Question 1

chlorhexidine

Answer 1

• Chlorhexidine and its analogues are commonly used at concentrations below 4% as skin cleaners, teat dips and antiseptics. They are also used for cold sterilization of surgical instruments and for disinfecting equipment, barns and buildings. Chlorhexidine has broad applications in cleaning dairy equipment and in aquaculture (bacteria, viruses, fungi) Also widely used but expensive

Question 2

Sodium hydroxide alkaline desinfectants

Answer 2

• In a 2% solution of sodium hydroxide is effective against many viral and bacterial diseases.
BUT corrosive, so it has been largely replaced with less corrosive and less irritating modern disinfectants
• BUT, in emergencies NaOH can still be an option, as it is readily available and extremely effective.
• It should be used with extreme caution and under well-controlled conditions, due to the corrosive and irritating properties, and potential dangers to the environment (metal objects) and to workers.

Question 3

inorganic and organic acids

Answer 3

The INORGANIC acids most commonly used in animal disease control are sulfuric acid and hydrochloric acid. Both of these are effective against FMD virus but are also highly toxic if swallowed, highly irritating to the skin and eyes, and very corrosive to metals. Thus these acids are used only in very limited situations

• A number of ORGANIC acids with bactericidal and mild viricidal properties have disinfectant applications in animal health and food processing, as they are less toxic and less corrosive than the inorganic (metallic) acids mentioned above. Acetic, citric, lactic, formic and propionic acids are sometimes used in meat and poultry packing plants, and in calf and pig barns. These acids have also been added to animal feeds to reduce levels of Salmonella contaminations

Question 4

Formaldehyde

Answer 4

• The natural form of formaldehyde is a gas. However, formaldehyde is more readily available as a 40% aqueous solution called formalin (preservation of tissue samples).
Gaseous formaldehyde is used for the fumigation of buildings, rooms or vehicles which can be sealed. Fumigation with formaldehyde is effective against most viruses and bacteria, including Mycobacteria (used to use for disinfecting eggs too)
• Formaldehyde gas is relatively unstable and can sometimes explode. For formaldehyde fumigation to be complete, the temperature must be above 13 0C and relative humidity
must be above 70%. Spraying with hot water is sometimes necessary to achieve these conditions. For fumigation purposes, formaldehyde gas can be produced by oxidizing formalin with potassium permanganate.
• A 1-5% formalin solution is sometimes used to disinfect buildings or as a prophylactic and therapeutic foot bath for foot rot in sheep and cattle. The use of formaldehyde in disinfectant situations is declining, due to the strong, irritant odour, orrosiveness, fibrolytic properties and toxicity. Teratogenic and carcinogenic nature → prohibited in EU! – now just use the formalin for tissue preservation

Question 5

important factors in control and eredication programs

Answer 5

• Level of knowledge about cause of disease and if infectious, its transmission and
maintenance, including host range and host parasite relationship (pathogenesis and
epidemiology)
• Veterinary infrastructure - field service, diagnostic and research facilities
• Diagnostic feasibility - clinical signs, pathological changes, isolation of causal agents,
demonstration of an immune, allergic or biochemical response, epidemiological identification
of changes of a variable on a population - e.g. a production parameter
• Availability of replacement stock (select and kill only some, use supplementary vax until generation
shift)
• Producer’s views - public relations: public view of stamping out (mink 17mill culled for corona NOW)
• Public opinion - e.g. badgers and tuberculosis, brucellosis
• The disease’s public health significance
• The existence of suitable legislation with provision for compensation – allow to go through with it
and compensate the farmer – can either force farmer help to pay (their loss if they’re culled) or they
will be compensated partially by EU

• The possible ecological consequences (e.g. tsetse control – insecticides, pesticides – may kill nontargeted
organisms)
• The economic costs and availability of funds for the program. Modelling and cost/benefit analyses