Thursday, June 29, 2017

South Africa Rejects Vaccination to Control Bird Flu


The arrival of HPAI H5N8 to South Africa last week has set off alarm bells among local poultry producers, and while only two South African farms have been confirmed infected, there are already calls to introduce a poultry avian flu vaccine.
While attractive to farmers who fear losing their flocks - and a mainstay of China's poultry industry - poultry vaccines bring with them some serious drawbacks (see MPR: Poultry AI Vaccines Are Not A `Cure-all’).
First, while vaccines can often protect poultry against illness - with increasingly diverse and rapidly evolving avian flu viruses - they cannot always prevent infection.  The end result being that subclinical infections can go undetected, and AI viruses continue to circulate.
That can not only allow viruses to spread stealthily, it can also put human health at risk (see Zhong Nanshan's 2009 comments in Chinese expert issues new bird flu warning).
And secondly, the use of poorly matched or improperly administered vaccines can actually drive the evolution of `vaccine escape' viruses (see cites below), which may account for some of the past decade's growing diversity of avian influenza in China.
The HPAI Poultry Vaccine Dilemma
Study: Recombinant H5N2 Avian Influenza Virus Strains In Vaccinated Chickens
         EID Journal: Subclinical HPAI In Vaccinated Poultry – China

Lastly, vaccinated poultry may not be readily accepted by foreign markets, since it hinders testing for the virus.  All good reasons why South Africa's DAFF has decided for now against using AI vaccines to control H5N8 in South Africa.
The following excerpts come from today's Media Briefing by Minister Senzni Zokwana.
29 JUNE 2017

The Department, in its alert notification, called for all chicken keepers to observe basic biosecurity measures in order to prevent contact with wild birds. This can be achieved in commercial farms by improving biosecurity and in free range farms by simply removing feed and water from where it attracts wild birds.
Despite the warnings, the disease still managed to get into our flocks. Two cases, one in a broiler breeder farm in Villiers and another in an egg laying farm in Standerton, were reported since 22nd of June. Both these farms are in the Mpumalanga province. There seems to have been confusion with the location of one farm which is near Villiers, as its closest town. I confirm that this farm is on the Mpumalanga side of the provincial boundary. No cases have been reported so far in the Free State, or in any other province.
Our team of veterinarians has swiftly responded to this threat. We have placed the affected farms under quarantine and the affected birds have been euthanised and the eggs destroyed. Approximately two hundred and sixty thousand (260 000) birds have been culled.
Section 19 of the Animal Diseases Act, gives the Director Animal Health the legal mandate to compensate for any animals or birds killed by the state pursuant to any disease control measure. The Director of Animal Health will consider each case on its own merit.

There have been several calls to permit vaccination against the disease; I have been advised by my team of experts that this will not be in the best interest of both the country and the producers. Vaccination of birds will create an endemic situation, affect surveillance efforts and affect our export certification because all our trade partners only want products from a country that is free of avian influenza where vaccination is not practised.
In order to contain the disease, our team called for the ban on the sale of live chickens to manage the further spread. This triggered a nation-wide concern since a number of livelihoods had been affected. However this measure was imposed in the interest of the country and the poultry producers at large, and I can assure you that it was not taken lightly.
My team has since met with the Poultry Producers and have devised a solution that will provide the desired disease management outcomes and improve traceability, while ensuring that micro businesses continue with their operations.
The buyers or sellers of more than 5 live chickens for any purpose other than direct slaughter at a registered abattoir will be subjected to the following conditions:
  1. The sellers of live chickens, including commercial farmers, as well as the traders who buy and resell these chickens must register with the Poultry Disease Management Agency (PDMA). The Director Animal Health, of the DAFF has authorised the PDMA to register and keep records of all parties selling and buying live chickens. The PDMA is an independent organization and all information about the trade of live chickens will be kept strictly confidential.
  2. Only registered sellers and buyers are allowed to trade and it is the responsibility of both the seller and the buyer to ensure that their counterpart is registered.
  3. Farmers may only sell live chickens certified as healthy by a veterinarian or Animal Health Technician.
  4. Traders may only sell healthy chickens and must keep records as prescribed.
  5. Sellers and buyers registering with the PDMA would have to sign an undertaking to adhere to the required control measures.
These conditions apply to sellers of live broiler chickens, live spent layer hens, live spent breeder birds, point of lay pullets and any chickens that may fall into these categories. The conditions also apply to any buyers and traders who buy more than 5 live chickens that fall into the above categories.
All stakeholders are implored to comply with the registration and other requirements that are designed to allow the trade of live chickens to continue without compromising animal health. Depending on the level of compliance that is achieved with these conditions, the Director Animal Health will review future requirements for blanket bans.
         (Continue . . . .)

This is the first serious intrusion of HPAI H5 into the southern hemisphere, and while the number of farms affected remains small, the long-term impact remains a big unknown. 

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