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Notifiable swine diseases in South Africa: Potential future risks, diagnosis and surveillance techniques

By Dr. Gary Bührmann, Chief State Veterinarian, Boland Veterinary Services, Western Cape Province on behalf of the Pig Vet Society
First let’s look at the definition of notifiable diseases since in South Africa they are usually called controlled diseases in terms of Animal Diseases Act 35 of 1984.  This is a disease where the State steps in, in an attempt to control it due to its’ infectivity and the high economic and health impact it would have on the country’s animal and human population, should it be allowed to continue unchallenged. They are exotic diseases not presently occurring in the country.  This may be a first time occurrence or it may previously have been eradicated from South Africa and this is a re-occurrence.In the true sense of the word a notifiable disease is one already present or endemic in South Africa, but one must still notify the Department of Agriculture (DoA) of new outbreaks to monitor incidence and spread. The state may step in if necessary or if it is felt that individuals are acting irresponsibly and are not attempting to contain it’s spread.
Lets briefly take a “trip down memory lane” to review what the illegal introduction of exotic diseases into South Africa has cost the country in the last few years.
In March 2004 PRRS (Porcine Reproductive and Respiratory Syndrome) broke out in the Cape flats spreading eventually to 144 holdings resulting in the death or culling of some 14 600 pigs and costing the state approximately R11,6 million  by it’s termination in October 2005.
This was followed in July 2005 by an outbreak of CSF (Classical Swine Fever) in the Worcester district of the Western Cape resulting in the death and culling of some 1 531 pigs belonging to 101 owners and costing the state another R1,9 million in compensation.
However, this paled into insignificance compared to the devastation the disease has ultimately caused in the Eastern Cape where ±460 000 pigs have been culled belonging to some 120 000 owners and costing the state at least R300 million in compensation costs. This however, excludes the cost of personnel and maintaining roadblocks on all the provincial borders from August 2005 until April 2007 which has amounted to probably in excess of R500 million! Thus the total economic damage as a result of the introduction of this one exotic disease into South Africa is in the region of R900 million — an amount we most certainly cannot afford!
Looking at the combined epidemiology of the introduction of both diseases into South Africa it would appear that both arrived in the country most probably off ships (fishing trawlers) via our poorly animal health regulated and policed harbours. The contaminated pork was illegally removed from the harbours (Cape Town for PRRS and Eastern Cape for CSF) as galley waste and found it’s way as swill, fed  illegally to pigs in informal settlements, and from here it was but a natural “jump” to end up in commercial units on the borders of these areas. Feeding of raw swill is illegal according to the Animal Diseases Act 35 of 1984 and may only be fed if “boiled for at least 60 minutes”.

International perspective on exotic diseases

If one investigates the priority and “fear” the introduction of notifiable diseases instills in various countries we see the utmost cautionary and stringent biosecurity measures being implemented to protect them:
The Australian Quarantine Inspection Services (AQIS) has a Generic Import Risk Analysis (IRA) for pork and in relation to the following disease agents the unrestricted risk of entry, establishment and/or spread was assessed as being too high to meet Australia’s ALOP (Appropriate Level of Protection):

  • Foot-and-mouth disease virus
  • African swine fever virus
  • Classical swine fever virus
  • Rinderpest virus
  • Swine vesicular disease virus
  • Aujeszky’s disease virus
  • Porcine reproductive and respiratory syndrome virus
  • Trichinellosis (Trichinella spiralis)
  • Nipah virus
  • Post-weaning multisystemic wasting syndrome (Porcine circovirus type 2)
  • Teschen (DEFRA)

Their (IRA) Report describes the procedures followed to identify and assess the quarantine risks associated with imports to Australia of pig meat. It presents recommendations in relation to proposed quarantine measures sufficient to ensure that Australia’s Appropriate Level of Protection (ALOP) is maintained. Biosecurity Australia released a Methods Paper that sets out the approach to the method for undertaking the risk analysis:

  • It outlines the release and exposure pathways, and the outbreak scenarios considered to be of importance in assessing the risk associated with the importation of pig meat.
  • It identifies the major exposure pathways for disease introduction through waste from households and waste from food service establishments.
  • Four groups of animals that may be directly exposed to uncooked pig meat scraps were identified and included feral pigs, backyard pigs, pigs in small commercial enterprises and susceptible species that will eat meat, i.e. dogs, cats and rodents.
  • The IRA also examines the consequences of spread to large commercial piggeries and other animals such as horses and cattle although this is not considered a pathway for direct exposure.

In conclusion, this IRA Report recommends that import of pork be permitted subject to:

  • Certain conditions depending on the health status of the exporting country or zone.
  • Risk management measures include such things as country or zone freedom.
  • Testing of the carcass, cooking, freezing, curing, canning and removal of certain tissues or parts of the carcass (removal of the head and neck, deboning).
  • For many countries seeking access that have both the diseases PRRS and PMWS, only cooked or cured deboned pig meat would be permitted, subject to those countries meeting all other requirements.
  • Or Biosecurity Australia will consider any other measures suggested by stakeholders that provide an equivalent level of phytosanitary protection.

Under EU Legislation the general guidance on EU import and transit rules for live animals and animal products from third countries falls under the Food and Veterinary Office (FVO) and since April 2006 the key provisions of the Directive, which domestic legislation implements are:

  • Animal health status and control, diagnostic capabilities, reporting  systems, surveillance, BSE, traceability, etc.
  • Residues monitoring, additives
  • Food safety standards, national authority standards/capacity
  • Import controls — borders
  • Veterinary and health certification standards with legislation, welfare standards, etc.

The OIE has a  Regional Commission for Europe which amongst other issues focuses on
live animal and food smuggling which they divide into unintentional (small amounts for personal use/seasonal movements) or intentional (avoid international trade rules due to economic issues) and they control these by:

  • Ensuring partnership between veterinary services and customs
  • Cooperation between national, provincial and international governments
  • Training assistance and capacity
  • Information flow between authorities and public.

Finally the DEFRA (Department of  Environment Food & Rural Affairs) of the UK facilitates the following to prevent these diseases entering their country:

  • International disease monitoring — monitor occurrence of major animal disease outbreaks worldwide as an early warning to assess the risk these events may pose to the UK.
  • SGDIA — Surveillance Group on Diseases and Infections of Animals — develops UK Veterinary Surveillance strategy.
  • Veterinary surveillance: List of published RADAR (Rapid Analysis and Detection of Animal-related Risks) veterinary surveillance reports.
  • Veterinary surveillance: Pigs — Everyone who keeps pigs must be either registered with Defra or the appropriate devolved administration. All pigs over one year old which move from the farm and all pigs under one year old going to the slaughterhouse must be identified. This can be by a slapmark on the shoulders, an eartag or an ear tattoo. We also collect information about the numbers and types of pigs during a census of farmers in June every year.
  • Diagnostics — veterinary labs
  • Biosecurity — publications, border and internal.

In comparison how does South Africa compare and what measures do we have in place?
1. AQIS – Animal quarantine Inspection Services implemented by the DoA which comprises Harbours (NPA — National Port Authority) and Airports (ACSA — Airport Company South Africa).
2. AQIS – Animal and plant inspection services at all our borders.
3. Presently there is an investigation in progress by the DoA to ascertain the level of biosecurity at all our ports of entry into the country.
4. SAPPO has in addition appointed a  private investigator to monitor and check all our main high risk harbours at least every six months.
So based on what we have at our disposal in South Africa what are:

1. POTENTIAL FUTURE RISKS

Having had an overview of what the International and local South African authorities have in place to combat exotic new diseases entering their countries, in spite of these seemingly adequate measures, there still always remains a potential future risk and so we need to pre-empt such entry scenarios to remain prepared:
A. Legal imports — all meat and live pigs enter under cover of a permit issued by the DoA and with conditions equivalent to EU standards, and the products are tested post arrival and so we would not regard this as a major risk route.
B. Airports — although controls are not that watertight, the volumes entering off the planes is very small and most of the products are cooked, so this is probably not a major risk area and accessibility to the waste food by potential swill feeders is relatively difficult.
C. Harbours — they still remain our highest and most serious risk area throughout the country due to illegal imports via smuggling, economics to avoid stringent protocols, bribes, no  enforcement of  NPA protocol (although on paper it appears good), lack of customs control and complete absence of any Veterinary Officials in our harbours to enforce controls on animal/animal product entry into South Africa.
When one views the structures and documentation it appears as if we have all entry routes well protected by the NPA. As cited in the Government Gazette, Vol. 446, No. 23715, 8 August 2002 in the General Notice 1409 of 2002 , their  White Paper on National Ports Policy contained in Provisions of the Constitution states that “commercial ports should fall within the exclusive competence of National Government and its structures”, not para-statals as is now the situation.
Excerpts from the NPA website highlight:

  • Identification of Significant Issues Concerning Waste.
  • Ports will conduct an inventory to determine who is producing waste, and the nature of waste being produced. Particular care will be taken to identify sources, types and quantities of hazardous waste, and to ensure that such waste is disposed of in accordance with this policy.
  • Tenants and operators will be required to cooperate with the NPA in this exercise, by providing the data required for the inventory. As a minimum, the information that they will be required to disclose is as follows:

(i) Nature of wastes generated
(ii) Amounts of each different types of waste generated within a  specific period, and
(iii) Method of disposal
• Waste from shipping, including quayside maintenance
Spent oil and lubricants : Paint  Solvents and waste detergents : Waste from ship maintenance activities : Sewage : Galley waste : Sweepings from hatches  and engine rooms : Slops from holds and tanks : Spilt cargo : Ballast water : General domestic waste : medicinal/medical waste : Spent batteries.
•  Waste collection areas for ship waste
Clearly designated areas will be located in each port, and equipped with skips or other appropriate containers, to acceptance of general, domestic            waste. The location of these areas will be indicated by large yellow signs with words “WASTE RECEPTION POINT FOR SHIP GENERATED WASTE” in English and appropriate foreign languages. Signs should be of the same size and design in all ports.
Although this all looks good in theory we see and have experienced a major problem with the enforcement of all these requirements by the NPA. This leaves a large hole in our first line of defence against incoming exotic viruses! Should the DoA not be  playing a primary function here seeing as it is their interests that are needing to be protected for the sake of agriculture in the country?

What do we have in place In South Africa?

The Western Cape (2004) and DoA have Animal Diseases Control Contingency Plans in place which include all the major exotic diseases which could in the future potentially pose a threat to South Africa. Obviously this list is not exhaustive but the principles for prevention, detection and control of any exotic disease outbreak would encompass the implementation of very similar contingency methods. These include immediate intensive and extensive implementation within the first 24 hours of for example movement controls, quarantines, establishment of a disaster management control centre, personnel mobilisation, logistics, etc.
Is this enough or is it going to be a knee jerk reaction to something they should have prevented getting here in the first place?
2. DIAGNOSTICS
Diagnostics always play a vital role in the detection of a new disease and hence have to be of the highest standard to avoid incorrect diagnoses or missing new previously unknown exotics. We have at our disposal the OVI (Onderstepoort Veterinary Institute) who have IDEXX ELISA test kits available for some of these Exotic diseases e.g.. CSF, PRRS, FMD, ASF at the FMD Laboratory. The PCR tests are very difficult to validate but these will become more accessible with time, although viral culture will always remain the “golden standard” as far as confirming the presence of a new virus.
Unfortunately at this stage our PVL (Provincial Veterinary Laboratories) are very limited in their diagnostic capabilities as far as exotic diseases are concerned e.g. only PRRS and CSF (IDEXX) and private laboratories are usually restricted due to low volumes and the economics.
The OIE Reference Labs are available in emergencies and have been used on both previous occasions to confirm the diagnoses of PRRS and CSF e.g. Weybridge.
3. SURVEILLANCE TECHNIQUES
In South Africa we can confidently assure the local farmers that we are continually and intensively monitoring the country to detect any new exotic disease as early as possible, if  they should arrive announced on our shores and find its way to our pigs or for that matter any other animal population. The methods we have in place include:

  • SAPPO’s annual survey which has been running for approximately the last nine years and has culminated in the testing for FMD, ASF, CSF, Ps Rabies (Aujesky’s), TGE, SI, PRRS, and Br.suis amongst others, on random imports/exports and regular annual surveys averaging regularly 1 420 (3×440 kits) from 80 to 100 farms per year. In 2006 due to the expansion of the surveillance project by the DoA 6000 samples mainly from commercial piggeries were tested, all coming back negative for all exotic diseases tested.
  • Provincial and national surveys involve the testing of at least 20 properties per month per province with ±20 samples collected per property. This equates to ±2000 properties or 40 000 samples per year mainly on communal or informal holdings or farms.  At the moment this only covers CSF and PRRS, but samples are stored in a serum bank for future use.
  • Local animal health technicians (AHT) or veterinarians on farm doing inspections and sampling will also detect other diseases clinically, which ultimately gives one the earliest warning of the presence of a new disease on a farm and is probably your most important “first line of detection”.

In spite of all the above which may instill a degree of assurance in us about the low risk of an exotic disease escaping our detection, ultimately though PREVENTION IS BETTER THAN CURE and this requires a concerted effort by all role players in the animal production industry in South Africa to get involved in issues such as:

  • Public awareness of the dangers to human and animal health and economic loss as a consequence of the inadvertent introduction of an exotic disease.
  • INCINERATORS at harbours and airports are an option which should be lobbied for to prevent any foreign waste food leaving these ports
  • National versus provincial veterinary services should have a clear role distinction and the DoA should prioritise control at the ports and have permanent Animal Health officials on duty at all high risk entry points. This is vitally important and needs urgent attention!
  • Auctions can play an extremely important role as control and monitoring points for all pigs which are not usually seen by any AHT or Veterinarian.
  • NPHS — National Pig Health Scheme — I believe is the one of the ways forward to ensure that every holding, no matter how small is visited by a knowledgeable pig veterinarian as this “old hands-on tried and tested scheme” has proved it’s efficacy before and can be worth more than it’s weight in gold in protecting us from another exotic disease outbreak in the future!

Notifiable swine diseases will thus always pose a future risk, so we need to use all means at our disposal to “look carefully, so we don’t miss anything”.  Even more importantly, let’s try and stop them before they leave our harbours again and get into our pigs!

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