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Highly Pathogenic Avian Influenza (H5N8) outbreak
Highly Pathogenic Avian Influenza (HPAI – also known as Bird Flu) has recently been confirmed in South Africa in the Eastern Free State (Villiers), Mpumalanga (Standerton) and Gauteng (Boksburg) provinces. It is the same H5N8 HPAI virus that caused an outbreak in Harare, Zimbabwe, a few weeks ago. HPAI is an extremely serious disease which can kill up to 100% of chickens in an infected house within 3 days. Some HPAI strains are able to infect other animals and people, although this specific strain is not known to cause disease in humans.
The disease spreads very rapidly and is most commonly introduced to chickens via:
- 1. Wild water birds: shed the virus in their droppings, virus is introduced by stepping in infected droppings and carrying them into chicken house.
- 2. Open Water sources: used for drinking water or in cooling pads.
- 3. Contaminated manure/ equipment / people / vehicles / animals and infected chickens (culls).
Signs of the disease include:
- 1. A sudden increase in mortalities.
- 2. A large number of birds showing respiratory signs and depression
The main aim of this document is to highlight the critical measures that SHOULD be in place on all farms to minimize the risk of introducing the disease. (Please refer to the DAFF Contingency Plan; the Avimune HPAI VCD and other HPAI literature for more information.)
Implement the following as a matter of extreme importance and urgency. Prevention by stringent biosecurity and auditing thereof to ensure that there are no breaks in the biosecurity protocol are the only ways to limit the risk the disease poses to your farm. There is NO vaccine and NO treatment:
- 1. Eliminate introduction from wild birds or free-ranging domestic birds
- a. Bird proof all houses.
- b. Keep doors closed.
- c. All free-range / outdoor poultry must be moved indoors
- d. Staff must not come into contact with any poultry or any free-range birds (includes ducks or any other birds which are outdoors.
- e. Ensure that feed silo lids are closed at all times and feed spillage must be thoroughly cleaned immediately to discourage the entry of wild birds onto site
- 2. Eliminate introduction from open water sources
- a. Seal (bird proof) all reservoirs and water tanks immediately.
- b. Implement effective chlorination of drinking water and water used for cooling pads:
- i. pH of water must be 6.5 to 7.0 for chlorination to be effective. Acidification must be done if the pH is too high.
- ii. Add hypochlorite (chlorine) to reach a 2ppm level.
- iii. Monitor effectivity of chlorination with an electronic ORP (oxidation reduction potential) meter on a daily basis. Target = 650 and 700mV.
- 3. Eliminate introduction via personnel
- a. The ideal is to introduce two pairs of boots – an outside pair and an inside pair (different colors). This inside pair must not leave the poultry house.
- b. Double disinfect boots by using two sets of boot dips: Two wet boot disinfectants or a combination of a wet followed by a dry boot disinfectant must be implemented.
- c. A brush must be available at the first foot dip so that any manure / mud / organic material stuck to the bottom of a boot can be brushed off into the foot-dip, taking care not to splatter these solids onto overalls.
- i. It is strongly advised that all personnel shower and change into dedicated clothes before entering a poultry house.
- ii. If this is not possible, every house attendant must have 2 pairs of 2 different color overalls and 2 pairs of 2 different color boots: Change into under clothes (e.g. PT-shorts and T-shirts) and site overalls which are a different color (e.g. red) and boots (e.g. white). At control room or at door of house, use double foot dip and take off site overalls (red) and boots (white), changing into house overalls (blue) and boots (black). Store outside clothes and boots in control room. After changing into house clothes, staff again use double foot dip (between control room and house or even one at door of house if no control room) before walking around in house.
- d. It is advised to use “Dwala Type A2″ Hydrated Lime to spread on concrete walkways and other high traffic areas.
- e. Ensure that all wild bird nests and droppings are cleaned and removed from the vicinity of the houses. Disinfect areas where bird droppings occur after cleaning.
- 4. Eliminate introduction by visitors or external service providers
- a. Immediately stop any non-essential movement of people or vehicles onto or off your site or farm. Any essential visitors and all managers should follow the same protocol as for staff below.
- b. Movement of the catching team between houses and between farms is regarded as high risk contact. Catching broilers at the end of the production cycle is inevitable; however, it is crucial to ensure that ALL biosecurity measures remain in place and that there is no contact between catching team personnel and houses which are not slaughtered yet. The catching or thinning of birds during the cycle at ages younger than regular slaughter age at the end of the production cycle, is discouraged. A potential introduction of disease onto farms and into poultry houses can be disastrous.
- c. Feed trucks and other essential vehicles must be disinfected (ideally through a spray race) with a glutaraldehyde disinfectant at the maximum recommended concentration. Let the vehicle drive forward half a meter to ensure spraying the part of the tyres which were in contact with ground during initial disinfection.
- d. Feed truck drivers must not exit truck. Feed truck assistant to shower / change into farm protective clothing and ride on the outside to the site to offload feed.
- e. Maintenance, rodent control and electrical contractors’ equipment must be fumigated or disinfected onto sites.
- f. When delivering biological samples to laboratories, ensure that personnel do not return to poultry houses on the same day.
- 5. Eliminate introduction via equipment
- a. Immediately stop any non-essential movement of equipment onto or off your site or farm. This include potential hazardous and contaminated catching crates.
- b. All equipment / egg trays / trolleys / etc. must be fumigated using an effective formalin based fumigation chamber or disinfected onto sites / houses.
- 6. Eliminate introduction via cull bird buyers at depletion
- a. Completely separate the cull buyer equipment and on farm equipment. Ideally use own farm catching crates and transfer to the cull buyer away from the farm.
- b. Disinfect all equipment back onto the farm
Please contact us immediately if anything is unclear or if you need contacts for suppliers of any of the equipment / items mentioned above. Please be aware that we have to limit our own movement and only perform essential visits for the sake of our clients and the industry.
The Avimune Team
Infection in brooding period (from 1 day of age) up to 4 weeks of age: Respiratory disease and “False Layers” and lower egg production at older age. The disease is characterized by rapid spreading and high morbidity, generally without secondary complications. Clinical manifestations: Respiratory symptoms that last~10 days. Sometimes nephritis is also observed. Mortality: 3-20% House-to-house spread may take several days (3-6 days). Exposure to IBV during the first 3 weeks of age can cause “false layers” in up to 25% of adult hens.
– In most severe cases egg production: 70-85% instead of 93-95%
– No other apparent clinical signs
Infection in the growing period (4 weeks of age to 18 weeks of age): respiratory disease.
Infection in the laying period (18 weeks up to 75 weeks of age): IB can cause respiratory disease, drop in egg production and egg quality.
Melamine contains 66% nitrogen by mass and is also a metabolite of cyromazine, a pesticide. It is formed in the body of mammals who have ingested cyromazine. It has been reported that cyromazine can also be converted to melamine in plants.
Lori 0. Lim, Susan J. Scherer, Kenneth D. Shuler, and John P. Toth. Disposition of Cyromazine in Plants under Environmental Conditions J. Agric. Food Chem. 1990, 38, 860-864
FAO report on Cyromazine:
Melamine use as non-protein nitrogen (NPN) for cattle was described in a 1958 patent and a study in 1978 Ruminant feed compositions, Robert W. Colby and Robert J. Mesler Jr., U.S. Patent No. 2819968, 1958 Melamine as a dietary nitrogen source for ruminants”, G.L.Newton and P.R.Utley, Journal of Animal Science, vol.47, p1338-44, 1978, Abstract Melamine by itself is nontoxic in low doses, but when combined with cyanuric acid it can cause fatal kidney stones due to the formation of an insoluble melamine cyanurate. Chronic exposure may cause cancer or reproductive damage. Eye, skin and respiratory irritant.” However, the toxic dose is on a par with common table salt with an LD50 of more than 3 grams per kilogram of bodyweight.
Cyromazine is a triazine insect growth regulator used as an insecticide and an acaricide. It is a cyclopropyl derivative of melamine. Cyromazine works by affecting the nervous system of the immature larval stages of certain insects. In veterinary medicine, cyromazine is used as a ectoparasiticide
Citation, Larvadex, Trigard, Vetrazin,
|Cyromazine Compound ID||47866|
|Molecular Weight||166.1838 [g/mol]|
|Melamine Compound ID||7955|
|Molecular Weight||126.11994 [g/mol]|
|Urea Compound ID||1176|
|Molecular Weight||60.05526 [g/mol]|
Biofilm appearance can differ from situation to situation and can have different colors including red, green, brown, cream, and clear. Many people that have experienced the problem and have seen the biofilm refer to it as “snot”. Places to examine for the presence of slime to determine if a biofilm problem exists includes regulators, filters, filter housing, medicator pumps, inside the water reservoir on evaporative cooling systems, and the water pipe itself.
Water pressure drop may also be an indicator of a biofilm problem as the buildup restricts the flow of water through filters and water lines. Another method of detecting biofilm problems would be to test chlorine (Cl) concentrations at the beginning and end of the water line. Microorganisms in biofilms will absorb or bind some of the Cl reducing the Cl concentration at the end of the line. Oxidative reduction potential (ORP) will also decrease down the water line if biofilm and/bacteria are present. The ORP is a measure of water oxidation levels in millivolts (mV) and higher levels are normally associated with better bactericidal properties. If a problem is suspected, a bacterial analysis of the well water and water lines should be conducted to determine the presence of bacteria.
According to the Merriam-Webster’s Medical Dictionary a biofilm is “a thin usually resistant layer of microorganisms (as bacteria) that form on and coat various surfaces (as of catheters or water pipes)”. The slime that these bacteria produce protects them from many sanitizers and disinfectants so that even farms that have water line maintenance programs can still have biofilm issues. Biofilms will acquire the chemical characteristics of the surrounding water environment and will accumulate microorganisms such as bacteria and viruses if they are present in the water and left untreated. These bacteria could be present from flock to flock unless the biofilm is completely removed. Biofilms can also reduce the effectiveness of medications, disinfectants, and make it difficult to conduct water analysis.