Together with Asian Poultry Magazine we published an in-dept article (September issue) on how to prevent and cope with contamination with a strict bio-security protocol.

The threat of avian influenza (AI) or bird flu is upon us once again and is rapidly circulating while severely affecting domestic flocks all over the world.

By Daisy Roijackers Manager Regulatory Affairs and Biosecurity at Intracare.

There are two variants of AI: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). Fortunately, LPAI is the more common one and infected birds show few symptoms. LPAI has been isolated from over 100 species of wild birds. Wild waterfowl carry the virus around the globe and are the natural hosts and reservoirs.

It becomes troubling if specific LPAI types (H5 or H7) adapt to the hazardous form: HPAI. Apart from causing severe losses from high mortality, HPAI causes respiratory issues such as sneezing, coughing, mucus-filled airways, and sinus congestion.

How can wild waterfowl transmit the virus?

During the seasonal migration, the virus is transmitted over long distances. Some species can cover thousands of kilometers. The life cycle of wild waterfowl includes stopovers on water bodies. Large numbers of birds gather, especially when a stopover is crossed by multiple flight paths. This leads to the exchange of virus types, further spread, and even emergence of new variants.

In nature, water is the ideal medium to preserve AI viruses and to transmit them. Fresh water with a temperature of 22°C can retain infectivity for four days. If the water temperature decreases, the period of infectivity that can be retained increases.

On main breeding grounds for migratory birds in northern Russia the virus can be preserved throughout winter in frozen water. When the birds come back in springtime and are exposed to melted ice, they can become infected again.

How does domestic poultry become infected?

AI is an unpredictable and continuous threat. Domestic poultry can become infected through direct contact with infected birds or their droppings, contaminated materials (food, crates, people) and via dust. But fresh water is also an important transmission route.

Since the wild waterfowl spend a lot of time in lakes, rivers, water reservoirs etc. they contaminate the water with the virus types they carry. If the drinking water system in a poultry house is connected to contaminated water, this poses a major risk factor.

What about vaccination?

Vaccination still has some hurdles to overcome. First, not all countries have a vaccine available. Or the available vaccine is not compatible with the current outbreak because it is based on a different virus type. If a vaccine is only partially effective, it could reduce the clinical symptoms but not the virus replication in the birds. This could lead to a ‘silent spread’ of the virus. This is not wanted, especially since humans can get infected with AI (mainly after close contact with infected animals or environmental contamination).

What can we do?

The best protection against this devastating disease is to tighten biosecurity on the farm. Since 1g of AI virus can infect an entire flock, it is essential to remove the hiding spots for the virus in the house.

Table 1: Water quality values in Relative Light Units (RLUs) and their definition.

This applies to all surfaces in the house, such as the walls, floor, outside of the drinking lines, but also to the inside of the drinking lines. On the surfaces in the house, it is clear to see the contamination with your naked eyes.

All the contamination should be removed with a thorough foam cleaner (Intra Foamcleaner). Afterwards the surfaces may look clean, but they can still harbor millions of pathogens including AI particles.

Therefore, disinfection after cleaning is key to guarantee a safe environment for the new birds.

The broad spectrum disinfectant Intra Multi-Des GA has excellent flowability and the ability to penetrate deep into the areas where virus particles can still hide (e.g. cracks in the floor). The long-lasting residual action of the product protects the barn until the new flock arrives.

The highway for AI transmission As contaminated wild waterfowl shed the virus in open water, including drinking water reservoirs, the drinking water system may be directly connected to the contaminated water. Cleaning and disinfecting the drinking water system is important in the prevention of AI.

Unfortunately, pollution in the inside of the drinking system is not easily visible as on surfaces. Biofilm that is present inside the drinking lines does not only act as a protective layer for bacteria, but also viruses can hide in this biofilm. The biofilm protects the pathogens from environmental, physical, and chemical exposure. Therefore, just adding a disinfectant such as sodium hypochlorite (chlorine) to the drinking water is not sufficient.

Research has shown that despite the addition of water disinfectants such as sodium hypochlorite, virus particles can remain in the biofilm (Ou et al., 2011). Many disinfectants fail to remove the biofilm and once the disinfectant is not on the water, the biofilm acts as a reservoir for subsequent spreading of pathogens to susceptible birds.

Biofilm that is present inside the drinking lines does not only act as a protective layer for bacteria, but also viruses can hide in this biofilm.

How to remove the biofilm Intra Hydrocare is an ultrastabilized drinking water cleaner and disinfectant in one. It is registered according to the new Biocidal Product Registration (BPR) by the European Chemicals Agency (ECHA).

This registration includes the application to disinfect the drinking water during the cycles and to remove biofilm from the entire water system. Meaning that the last part of the water lines is also cleaned and biofilm free. This is clearly visualized in the following trial performed in Thailand. Two lines were treated with peracetic acid (line 1 and 3) and two lines were treated with Intra Hydrocare (line 2 and 4). Afterwards the water is rinsed out of the system and collected in bottles.

Figure 1 shows the result of the collected water. The water in bottles 1 and 3 is colorless, while the water in bottle 2 and 4 is polluted with biofilm. A dark color means there is more pollution. In other words, Intra Hydrocare, dosed in lines 2 and 4 was able to remove the biofilm, which is rinsed from the system into the collected water. While peracetic acid did not remove any of the biofilm.

Figure 1: Collected water. Bottles 2 and 4 have a darker color, meaning the biofilm was released from the inside of the drinking water lines and is rinsed out of the system into the bottles. Bottles 1 and 3 remain colorless, meaning that the biofilm is still present in the drinking lines.

Besides cleaning the surfaces of water lines, Intra Hydrocare disinfects the drinking water itself. Amongst many others, the efficacy of the product for AI (EN14675) has been studied. The study was passed, and it was concluded that Intra Hydrocare can inactivate bird flu for 99.99%. How to check water quality?

The quality of the drinking water can be measured with the Intra Clean Quick Scan. This is a device that measures within seconds the energy content originating from living organisms, such as bacteria, expressed in relative light units (RLU). The higher the RLU value, the worse the water quality. The ranges available in Table 1 show the definition per water quality value.

It is important not only to measure the incoming water but also the water coming out of the last nipple. Often the incoming water quality is good, but problems arise in the pipelines. Water lines are long, and in the end of the lines, the water temperature is higher. This promotes microbial growth and biofilm formation, which affects water quality.

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