The organization of the control operation
Movement controls on pigs
Mass culling of active disease farms
A national testing and surveillance programme
A national abattoir monitoring and testing programme
Outbreak control operations require a high level of organization across the spectrum of legislative, managerial, logistical, technical, and procedural activities. Thus, advance planning for the emergency management of disease outbreaks is the first step in effective outbreak control. The Australian AUSVETPLAN provides a useful model for such planning (Daniels 2001), encompassing plans for:
- management activities (control centres, high level coordination, information management, laboratory preparedness);Any plan for Nipah virus preparedness should comprehensively address:
- control procedures (destruction and disposal of animals, valuation and compensation, decontamination of premises);
- various livestock enterprises; and
- various known diseases.
- laboratory preparedness issues, such as biosafety, scientific skills, quality assurance, epidemiology, technology transfer (see Chapters 2, 3 and 4);The remainder of this chapter outlines the stamping-out approaches adopted in the Malaysian outbreak (Nor & Ong 2000; Ong et al. 2000; Mangkat 2001).
- diagnostic methodologies (see Chapters 3 and 4); and
- control and eradication techniques (this chapter), pig industry issues, such as farm biosecurity and herd health monitoring (see Chapter 6).
Importantly, the Department of Veterinary Services (DVS) of Malaysia had legislation in place that enabled Nipah virus to be declared as a new notifiable disease, and facilitated the control and prevention of spread of the disease by empowering the DVS to declare disease control and eradication areas. The Director of the Department of Veterinary Services in each state was thus able to prohibit the keeping, movement, sale, or slaughter of pigs, and to order the examination and destruction of infected or suspect infected animals, and the closure and destruction of premises.
A taskforce of relevant Ministers, Deputy Ministers, and Secretaries General was set up by the Cabinet. Their role was to provide policy direction, to coordinate the functions of the various Ministries and Departments involved, and to closely monitor progress. Major decisions such as the depopulation of infected zones, the demolition of pig farms, the evacuation of villagers, and the payment of compensation were made by the Cabinet Taskforce. In each affected state, special committees chaired by the Chief Minister or State Secretary were established. These committees coordinated all control operations in the state, monitored the outbreak situation, and reported to Cabinet Taskforce. In districts where major culling operations were conducted, district committees were set up to provide logistic support.
In addition, technical committees were established to carry specific activities - to act as Secretariat for the Cabinet Taskforce, to coordinate and monitor field and laboratory studies on disease investigations, to provide technical input to the culling operation, the payment of compensation, surveillance and logistics support, and public awareness and education programmes. The DVS set up a 24-hour operation room to coordinate and supervise the control operation with the state veterinary authorities, to convey DVS and Cabinet Taskforce directives to the state veterinary authorities, to provide and monitor the budget and logistic requirements of the state veterinary authorities, and to facilitate the flow of data and information to operations room and Cabinet Taskforce, and to act as a resource centre for other agencies, the media and interest groups.
After Nipah was declared as a disease under the legislation, all movement of pigs or pig meat (local, intrastate and interstate) was banned with immediate effect by cancelling all previously issued permits. Media releases and public notices were used to advise of the restrictions. The ban was enforced by increased DVS and police patrols on roads from infected areas. The movement ban was later amended to allow the movement of pigs outside declared zones to Government abattoirs, with each consignment transported under permit and escorted by DVS officers.
Infected zones of 2 km radius and buffer zones of 10 km radius were imposed around infected premises. All pigs within the buffer zone were culled over a 2-month period (a total of 901 228 pigs from 896 farms). The Department of Veterinary Services, the Department of Transport, the Army, other related government agencies and non-government organizations were involved in the culling operation. Prior to culling, farm owners were served with a notice of culling. Farmers and residents were evacuated, and the area sealed with police roadblocks. All personnel involved in the culling operation were reminded to put on personal protective equipment before entering infected areas.
The pigs were culled by shooting, and disposed of by burying in deep pits within the infected area, either on-farm or off-farm (see Figure 5). Chlorinated lime and detergents were used to disinfect premises and burial sites (see Figure 6). Evidence of infection of dogs in one outbreak area prompted a decision to shoot all stray dogs in infected areas. At the same time, peri-domestic animals and dog studies were conducted to determine possible transmission of virus through these animals.
Figure 5: Culling and disposal by shooting and burying
Figure 6: Disinfection of burial sites using chlorinated lime
The Malaysian Government approved establishments of two funds: the Humanitarian Fund - to relieve hardship caused by the loss of family members, and the Nipah Trust Fund - to provide financial assistance for the pigs culled. A committee headed by the Secretary General of Ministry of Agriculture operated the trust funds, with the day to day management entrusted to the DVS Director General.
As the culling programme neared completion, a national testing and surveillance programme was implemented to determine the Nipah status of all pig farms in Peninsular Malaysia. The programme resulted in the culling of a further 50 seropositive farms (Ong et al. 2000), and enabled a claim of freedom from Nipah virus infection in the swine population of Peninsular Malaysia.
The third phase of the Malaysian Nipah virus control and eradication programme involved ongoing monitoring of pigs sent to abattoirs. The programme incorporated a trace-back system based on ear-notch identification to allow pigs to be traced back to farms of origin. The porker class of pig was targeted for screening, as the presence of antibodies in pigs of this age denoted infection on the farm of origin within the last four months. The programme aimed to demonstrate that Nipah virus was not circulating on pig farms, and thus to restore public confidence in pork consumption.