Clearing a Continent: The Eradication of Bovine Pleuropneumonia from Australia

By LG Newton and R Norris

Pleuropneumonia has had a long history in Australia. Clearing a Continent: The Eradication of Bovine Pleuropneumonia from Australia is an authoritative monograph on the history, spread, and final eradication of the disease.

Based on an enormous amount of research and archive material, the text details the background of the first outbreak, the spread through the affected states, the battle for control, as well as the persistence of the disease in northern areas long after it had been brought under control in the south. There is also vital information on vaccination.

This work is an important resource not only for those with a need for historical information on disease in Australia, but also as a reference for countries throughout the world to provide a better understanding of the behaviour of the disease.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Sep 1, 2000
• ISBN: 9780643102460

Book preview

CHAPTER I

An Overview of Pleuropneumonia in Australia

Although all three great cattle plagues of history, foot-and-mouth disease, rinderpest, and contagious bovine pleuropneumonia entered Australia, after European settlement, only the last became established. It entered at Melbourne in October 1858, in a group of five Shorthorn cattle for the Boadle farm at Darebin Creek on the outskirts of Melbourne. The disease spread, silently in the Melbourne precinct for almost a year and then in 1860 exploded across Victoria, New South Wales and Queensland to reach, the Gulf of Carpentaria, by 1864. Eventually it became endemic in the great herds of northern Australia. As the major markets were in the south, many thousands of cattle travelled, south each year to meet the demand. Some carried the disease, and so it repeatedly retraced its steps to the southern States from which it had been meanwhile eliminated. It was these incursions that, brought calls for eradication. The disease had been present for just 100 years when the Standing Committee on Agriculture in 1958 set up a sub-committee to control and consider eradication. The field program, commenced in 1961, was remarkably successful. The last, viable lesions were found in 1967 and, after five years of monitoring, mainly at, abattoirs, the country was declared free of pleuropneumonia in, 1973.

The pleuropneumonia, story is a fascinating one and some of the highlights are set out in this overview.

Pleuropneumonia in the nineteenth century

Victoria

The Port Phillip Farmers Society in Melbourne had become increasingly concerned at reports of sickness and deaths in Boadle’s herd and a meeting called in September 1859 to consider the possibility that pleuropneumonia was the cause appointed a committee to investigate. The committee enlisted the help of veterinarian John Miscamble. He carried out necropsies which confirmed pleuropneumonia and a decision was taken at a further meeting to destroy the herd and pay the owner compensation. The committee then framed a Bill designed to ‘annihilate the disease’ and presented it to the Chief Secretary, but no action was taken by the Government. On 31 July 1860, with further evidence of spread, the Society petitioned the Government seeking ‘prompt measures to arrest the ravages of the disease’. The petition was heard the next day, but it was not until 5 September that $4000 was voted for compensation for owners who had their cattle destroyed voluntarily. However, the disease gathered momentum and public pressure forced the Government to introduce legislation; the Act came into force in April 1861. Three remunerated Commissioners were appointed with increased powers but they faced an impossible task. Teamsters’ bullocks, which became infected in Melbourne, operated far and wide. Fences were often in disrepair or non-existent and sick bullocks were left on farms. Owners were generally indifferent to the disease, and the Commissioners were called in ‘only when the ravages of the disease rendered compensation a desideratum in return for which we could neither secure information, co-operation or precautions’.

The Government had little enthusiasm for the project. In retrospect, it is easy to be critical, but the Government was assailed on all sides by conflicting opinions. Disease at that time was generally thought to be due to miasmic influences or cold foggy conditions; the concept of contagion had scarcely arisen. When the disease began to spread rapidly, it behaved as a virulent epidemic. From 25 to 75 per cent of affected animals died but its virulence quickly abated and afterwards it was usually only in herds not affected earlier that it was severe. Owners resorted to many home remedies, the most diabolical of which was applying kerosene to the hair over the ribs and lighting it. Veterinarians blistered, rowelled and ‘bled animals copiously’.

It appears that Graham Mitchell, a Scottish veterinarian who practised at Donnybrook near Melbourne, was the first to inoculate cattle. When Hooper’s herd, the second to be killed, was destroyed in August 1860, Mitchell obtained a quantity of ‘virus’ (inflammatory exudate) from diseased lungs and inoculated healthy cattle which he later placed in contact with diseased animals; they remained healthy.

John Miscamble, a pioneer of inoculation, inoculated his first herd in April 1862. It was a valuable herd of which 60 had died and three or four succumbed daily. He mixed matter from the trachea and the lung surfaces on a plate and scarified the mixture into the tail tip. Losses ceased quickly, and he also became a staunch advocate of inoculation. He prepared and sold a product which he called ‘absorbent’. With Mitchell he was credited with establishing inoculation in Victoria. Mitchell was appointed Government Veterinary Surgeon in 1873 and it is due to his efforts and those of the Chief Inspector of Stock, E M Curr and his staff, that the disease was under control at the end of the century.

New South Wales

When the disease appeared in New South Wales early in 1861 the Minister for Lands appointed Alexander Bruce, pound keeper at Ten Mile Creek (now Holbrook) an Inspector of Cattle, to deal with it. Under newly introduced legislation diseased stock were to be destroyed and compensation paid, but only if owners had reported the sickness. Bruce quickly saw the futility of destruction of only visibly sick cattle, and the Government agreed that whole herds should be slaughtered. A Commission was set up to determine the limits of spread. It was agreed that if spread occurred beyond certain boundaries eradication would be impossible. Surveys revealed that it had so spread, and the Commissioners reported accordingly in January 1862. They recommended in their report the appointment of inspectors and measures to control the disease but the Government, like its Victorian counterpart, failed to act and the legislation lapsed in 1862. Some 8000 cattle had been destroyed. Bruce looked for an alternative method of control. He recognised that the cattle were generally too wild for close examination and of too little value for costly treatment; any control method therefore had to be cheap, simple and easily applied. None of the treatments used were apparently effective so he turned to inoculation. He experimented with many techniques until he settled on the insertion with a spaying needle of a thread immersed in virus. He was convinced that the disease was contagious and inoculation was the only means of control.

Queensland, Northern Territory and northern Western Australia

Cattle movements into Queensland after 1859 marked the start of some very long journeys, which eventually reached the very north of the continent. None surpassed that of nearly 5000 km in about two years by Charlie McDonald who set out from Goulburn in southern New South Wales in the mid-1880s, passed through Queensland and went, via the Gulf, generally westward to establish Fossil Downs at the junction of the Fitzroy and Margaret Rivers in the Kimberley region.

Alarmed at the rapid spread of the disease through New South Wales, the Queensland Government introduced legislation in January 1862 to prevent its entry but under pressure from pastoralists the Act was suspended in July 1862. A year later on 8 July 1863, a Mr Brooks reported to John Jardine, Police Magistrate at Rockhampton, that the disease was in his mob at Marlborough 13 km to the north. He had left Monaroo station near the Victorian border in November 1862, and sick and dead cattle were left on the track. With Edward Gregory, a veterinarian who had been appointed Inspector of Diseased Stock, Jardine proceeded post-haste to Marlborough and the disease was confirmed by necropsy of three animals. The property was quarantined and the local police constable placed in charge. Jardine returned to Rockhampton where he arranged a meeting of interested persons. They decided to destroy the rest, of the cattle and pay compensation. Jardine hurried to Brisbane to advise the Government and the Act was again brought into force in January 1864. Though it contained provisions to restrict movement of diseased cattle and for compensation for infected cattle destroyed, these measures were not enforced. A Select Committee, set up in May to enquire into the disease, recommended that prohibition on entry of cattle should be maintained, that only diseased cattle should be destroyed and that associations be set up for control of the disease by preventive and sanitary measures in each district; financial help by the Government would be necessary to defray salaries of inspectors for such work.

Other infected mobs soon followed. Jardine told the Select Committee that there were sick animals in a mob bound for the Burdekin area soon after Brooks’ cattle passed through. Other witnesses mentioned the involvement of bullock teams, some of which were wiped out. Edward Palmer later wrote that cattle on the way to the Gulf from the Clarence River area in New South Wales were affected in 1864; a mob was also held up inland from Bowen for inoculation in the same year. The disease spread out from ‘the great north road’ like branches of a tree and most of Queensland was involved by 1870.

Its northerly advance was halted temporarily until leases in the north of South Australia, now the Northern Territory, were stocked at the end of the 1870s when Queensland mobs were quickly on the move. The only access route was the one taken earlier by explorer Leichhardt just inland of the mouths of the Gulf rivers to the Roper River, which they followed along its course. The mobs could not cross the Barkly Tableland as it lacked water. Among the first were two mobs for Glencoe station north of Katherine in 1878 and 1881. The latter, which totalled 20 000 cattle, was split into 10 groups including 4000 cows from Richmond Downs where infected animals had gone earlier. Other stations to which the disease had been taken from Queensland in those early years were Wave Hill in 1883, Elsey in 1885 and Valley of Springs in 1885 and from that property to Lake Nash in 1891. The disease began to retrace its steps south from Austral Downs in bullocks that travelled via the Channel Country to Bourke in 1890 and along the Barkly stock route soon after it was opened in 1902. The early cattle into the Alice Springs district came from the south and this area seems not to have been infected until later when cattle were introduced from more northerly leases.

Pleuropneumonia was introduced into the east Kimberley area by cattle from Queensland. The first mob, destined for Ord River station in 1883 had travelled for some time with the diseased Wave Hill cattle; they could hardly have escaped infection. In 1885 the Durack mobs on their way to Argyle Station were inoculated to control the disease while they were at the McArthur River in the Gulf area. That the disease was well established in the Ord and Victoria River areas at the turn of the century was evident from lesions found at Fremantle in four shipments of bullocks, one in December 1903 and three in May 1904, from Ord River, Wave Hill and Victoria River Downs stations.

On the other hand, the West Kimberley area, which is cut off from the east by the King Leopold Range and further inland by the Great Sandy Desert, was stocked with cattle from the south-west of Western Australia in 1883. East Kimberley cattle generally moved north and east, and it was not until 1928 that the disease occurred on stations in West Kimberley. It was thought that inadvertent contact with East Kimberley cattle awaiting shipment from Derby was responsible. However, conditions for the disease seemed to be unfavourable and after spreading for a few years it apparently disappeared.

Pastoralists in Queensland who had quickly adopted inoculation in diseased herds, began to inoculate as a preventive measure. Archibald Archer, a prominent Rockhampton pastoralist was the first to inoculate. He found it successful. Preventative inoculation spread rapidly as inoculated cattle, especially working bullocks, brought better prices. Soon after P R Gordon was appointed Chief Inspector of Stock in 1872 he set aside an earmark for inoculated cattle, which won him friends among both drovers and pastoralists; some drovers insisted that cattle be inoculated before they travelled.

Gordon was instrumental in having the French scientists Germont and Loir of the Pasteur Institute in Paris, who were engaged on anthrax investigations in Sydney, visit Queensland to try to culture the organism of pleuropneumonia; and if that failed to find a better way to preserve the virus. They arrived in Brisbane in November 1889, where a laboratory had been fitted out and an area for experimental animals provided. When they were unable to grow the organism they demonstrated the collection of the ‘virus’ from the chest cavity of natural cases aseptically in glass tubes and bottles. It remained potent for at least three weeks. Then they passaged ‘virus’ through a series of healthy animals as Mitchell had done (neither they nor Gordon apparently knew of Graham Mitchell’s work) and from the large swellings that resulted they could collect sufficient of what they referred to as ‘cultivated virus’ from a single beast to inoculate about 1000 cattle.

Gordon regarded this as a great advance. Depots were set up in Rockhampton and Townsville to produce ‘cultivated virus’. Gordon managed a depot in Brisbane. In 1893 a laboratory, the first in Australia, was established in Brisbane with C J Pound in charge to cultivate ‘virus’ and carry out research. Although ticks and tick fever soon replaced pleuropneumonia as the most important disease, Pound continued to send out ‘virus’ until the Council for Scientific and Industrial Research (CSIR) vaccine became available in 1935. He found, however, that the ‘virus’ became attenuated on passage and little inflammatory exudate was produced. He then had owners and stock inspectors send ‘virus’ from natural cases to the laboratory where he examined it for contaminants, added glycerine as a preservative and despatched it to users. This was a remarkable service; in the early years ‘virus’ was despatched to all other mainland colonies for cultivation or inoculation but most was used in Queensland. More than 100 000 doses were sent out in some years.

South Australia

W S Smith, Chief Inspector of Stock of South Australia from 1954 until after pleuropneumonia was eradicated, believed the disease had entered in the latter half of 1863 via Wellington, which had been the only crossing place for stock from Victoria for many years. It penetrated rapidly into Port Augusta and the Flinders Ranges in bullock teams and by the end of 1864 was well established in the colony except for Kangaroo Island and Eyre Peninsula, which never became involved.

Southern Western Australia

No outbreaks occurred in the south-west portion of Western Australia until 1897.

Tasmania

Pleuropneumonia never occurred in Tasmania.

Federation and disease control

By the end of the nineteenth century all colonies had, or were about to have, effective disease control legislation administered under a Chief Inspector of Stock within a government department. The colonies entered into a Federation of States in 1901 but the States remained responsible for disease control within their own borders and each developed disease control legislation which regulated interstate movements. Other than for quarantine and meat inspection, there was no official co-ordination in matters of animal health and disease between the Commonwealth and States and between States until 1941. In that year, with war imminent on Australian shores, by resolution of the Australian Agricultural Council, Commonwealth and State veterinarians met to review measures to prevent entry and combat exotic disease and to deal with epidemic disease already in Australia. Thus began the Biennial Conference, which was replaced by the Commonwealth and States Veterinary Committee in 1968; the Pleuropneumonia Sub-committee became one of its several sub-committees.

Moves towards eradication in the south

Four States had moved towards eradication by the 1930s. Each used a different approach and their procedures are described separately.

Victoria

The dairy industry had become very important and legislation to improve health and hygiene standards in the industry was introduced in 1905. S S Cameron moved from Public Health to the Department of Agriculture to administer the Act and was appointed Chief Veterinary Inspector in 1906. Under the Act dairy herds were subjected to regular veterinary supervision. At the time pleuropneumonia was endemic and was detectable often only by reduced milk flow and a slight elevation of temperature. Cameron believed that affected animals never recovered and should always be destroyed. When the disease was suspected, temperatures were taken and if elevated to 40°C the animal was slaughtered and the rest of the herd inoculated and quarantined for 12 weeks. This procedure proved remarkably effective and the disease was almost eliminated by 1914.

Enlistments of veterinarians in the First World War disrupted this service. Quick firm action was not possible, and when the disease was uncovered many animals were affected and sometimes most of a herd was slaughtered. Farmers’ livelihoods were affected, they became reluctant to report sickness and clamoured for compensation. The Government was sympathetic but it took some time to find a suitable formula. In 1925, a Cattle Compensation Act was introduced to cover certain diseases, among them pleuropneumonia. After a brief period of uncertainty its terms were adopted in toto. The rigid control policy was then pursued without hesitation and by 1929 the disease was eliminated though sporadic outbreaks and sometimes severe epidemics were still caused by introduced cattle. In these cases, every effort was made to prevent contact of introduced with resident cattle and to trace their movements, to locate and check all in-contact cattle and, with the same strict policy, they were usually easily eliminated. Strangely, Victoria was the only State to use such a scheme for so long and so successfully.

The need for a reliable diagnostic test was recognised before the First World War. Johnstone, Heslop and Turner pioneered the search and in 1926 Gregory continued and extended the study of the Titse and Giese complement fixation test (CF) begun by Turner. It was used successfully in the late 1920s but positive reactions due to prior inoculation and ‘fleeting reactions’ caused difficulties.

New South Wales

Legislation in 1902 had achieved reasonably good control, but when Max Henry became Chief Veterinary Surgeon of the Department of Agriculture, New South Wales in 1923, he believed the aim should be eradication. He too believed slaughter of diseased animals was imperative. New legislation was introduced to allow owners to give an undertaking to observe quarantine in lieu of a public notice. With the stigma of public quarantine removed, owners more readily notified the disease, and it could be dealt with quickly. Lung specimens from suspected pleuropneumonia cases had to be sent to the newly opened Veterinary Research Station at Glenfield.

Henry next decentralised administration to enable more direct and faster action for disease control. In 1925, two districts were set up under the control of district veterinary officers with headquarters at Armidale and Orange. The scheme worked so well that eventually eight districts were established.

By 1927 the north and central coastal dairying districts had been free from pleuropneumonia for 10 years. To ensure their continued freedom a quarantine line was placed around the appropriate pastures protection districts and cattle were allowed to enter only with a certificate that they were not infected and had not been in contact with animals affected with pleuropneumonia. This isolated about 750000 valuable dairy cattle within the Casino-Port Macquarie Protected Area. The protected area concept proved so effective that it was subsequently applied to the Kiama-Braidwood-Kosciuzko Area. Other States later used the principle in somewhat similar circumstances.

By 1930, W L Hindmarsh bad developed a CF test at Glenfield based on the Titse and Giese technique. At first it was used to eliminate a number of outbreaks without recourse to inoculation. It was then used to eliminate endemic disease from the Sydney metropolitan dairies. From 1945 outbreaks in New South Wales were caused by introduced infected cattle.

South Australia

Procedures similar to those used in dairy herds in Victoria were used for dairy cattle in South Australia but beef cattle introduced for slaughter continued to be a problem. Many were fattened alongside dairy cows on the Adelaide Metropolitan Sewage Farm or on the irrigation farms developed for ex-servicemen around Murray Bridge. Proclamations prohibiting access by beef cattle to these areas in 1924 and 1926, respectively, ended these foci of infection. An even more important development was the proclamation in 1932 that prohibited movement of cattle south of a line from Ceduna through Quorn to just south of Broken Hill except under certain conditions. All northern and interstate cattle destined for slaughter at Adelaide or for fattening in the south-east of the State had to pass through Quorn, which was an important spelling, trans-shipping and selling centre. Under the proclamation, cattle for fattening required a permit, which provided for isolation by at least 6 m from other cattle and if disposed of within 90 days they could only be slaughtered at the Adelaide abattoir. Very few subsequent outbreaks occurred, the last was in 1952.

Western Australia

The relative isolation of the south-west of Western Australia enabled it to remain free of bovine pleuropneumonia until 1897. The first incursions were from South Australia but most resulted from East Kimberley cattle, either through abattoir saleyard contact or store stock released to farms in districts around Perth for fattening. East Kimberley cattle were not released after 1914 because of risk to local cattle but West Kimberley cattle continued to be allowed out as the disease was unknown there. Consequently, the discovery of lesions in a West Kimberley shipment in 1928 came as a shock. When eight stations were found to be affected in 1929, the disease was seen to be spreading. No cattle were allowed out for fattening but owners in the south-west, with three-quarters of the State’s beef cattle and all of its dairy cattle, feared the disease may gain a foothold there. So the Government introduced regulations in October 1929 that prohibited movement from north of 19°S latitude except for slaughter and only by sea. West Kimberley pastoralists felt themselves seriously disadvantaged and indeed they had a problem as some owners who had overlanded their cattle had to travel north through tick infested country to reach the port and those who sold store cattle were also penalised. The situation worsened in 1930, when the disease was found on 13 stations and others were of doubtful status. The matter was brought to a head when a beast from the south-west became infected through abattoir saleyard contact. It was taken up in Parliament, which resolved in favour of a Royal Commission. Max Henry, Chief Veterinary Surgeon, New South Wales, was appointed Royal Commissioner in 1931. His report after a thorough investigation, not only supported the Government’s stance but went even further in recommending that the quarantine line be moved further south to the 20°S latitude as he considered the existing line did not offer sufficient protection. The Government was still left with the dilemma of finding a solution, but the problem was solved a few years later with the CP test. The last outbreaks in the south-west were small and occurred in 1942.

Research for further progress

The beef industry in northern Australia, particularly Queensland, produced nearly all of the country’s export beef in the 1930s but it was hampered by serious disease problems. Pastoralists urged the recently formed Council for Scientific and Industrial Research (CSIR) to carry out research, but it lacked funds and facilities to do so. However a co-operative arrangement was reached between the Empire Marketing Board, the Queensland Government and the industry for funding for five years and the Stock Experiment Station at Oonoonba, Townsville, was made available by the Government. A team of CSIR scientists led by A W Turner began research on several projects, including one related to vaccines, in 1932. Initially a local strain C288 was used but it was insufficiently virulent to produce lasting immunity and was replaced by the V5 strain isolated in Victoria in 1936. The V5 strain continued to be used until the disease was eradicated. This was one of the most important developments in the fight against the disease.

Meanwhile Campbell had developed a very efficient complement fixation test (CF) test, based on the Wasserman technique, which was later adopted by many countries. The CF test was put to immediate use in Western Australia. A method for collection and preparation of large numbers of blood samples for dispatch to the laboratory 1600 km distant had first to he worked out. A few drops of chloroform proved an effective preservative. In 1934, 2200 cattle from one station were tested successfully. From then on cattle were tested each year and an inspector was stationed at Wallal in the Kimberley Division in 1938 to facilitate this.

Both Victoria and New South Wales were keen to dispense with vaccination. They believed it sometimes failed to protect, it could set up infection, it could mask carriers, and it certainly caused severe tail reactions. When the CF test became available attempts were made to eliminate outbreaks with the test alone. For a time they were successful, but both States found that in many outbreaks vaccination was essential to halt the disease. It became the policy therefore to vaccinate at the time of sampling for the CT test, destroy positive reactors and apply a second test usually not less than five months later.

Both States also endeavoured to protect themselves by increasingly stringent movement restrictions on introduced cattle. In 1942 New South Wales placed a quarantine line along the southern border of those pastures protection districts that adjoined Queensland and cattle from that State were obliged to remain north of the line for 180 days during which they could be subjected to inspection. Victoria, in turn, required cattle, other than for immediate slaughter, to stay in New South Wales or South Australia for 180 days.

The position in northern Australia

Pleuropneumonia persisted in northern Australia long after it was effectively controlled or even eradicated in the southern States. Among the important reasons for this were: size, climate, distance, land tenure, isolation and finance. Properties were often of immense size with herds of cattle of 80 000 or more. Few had fenced boundaries. Climate affected husbandry. In the dry season mobs of a thousand or more watered at bores, dams or lagoons but in the wet season they scattered widely, often to adjacent stations. To get to markets each year’s turn-off traditionally travelled a vast network of stock routes, some involving 1600 km of walking.

As early as the 1880s and 1890s these travelling mobs suffered outbreaks even though the disease had not been seen on the holding from which they came and owners resorted to inoculation to prevent infection. Until the 1950s the main vaccine usage in northern Australia was in connection with travelling cattle. The time and distance factors in marketing stimulated the development of roads and road transport to rail heads or direct to abattoirs. By 1959 some 25 per cent of Northern Territory cattle were moved by road and the percentage increased spectacularly to 76 per cent in 1965. A similar dramatic increase took place in Queensland from 2 million to 4 million between 1962 and 1966. Many people were firmly of the view that road transport, by relieving the stress and fatigue of travelling on the hoof and greatly reducing the time the animals were in close contact, contributed considerably to the success of the eradication campaign.

Disease control in the Kimberley District and the Northern Territory had been very limited before the Second World War but, after Darwin was bombed in 1942, the Northern Territory north of Birdum was placed under military control. A veterinary unit commanded by Major A C McKay was established to watch for exotic diseases and control endemic ones. Staff were located at Darwin, Halls Creek, Elliott and Alice Springs. In December 1944, McKay issued an order that all stock that travelled on Northern Territory stock routes in 1945 were to be vaccinated against pleuropneumonia. The order was modified the next year to allow his staff discretion where the disease was not endemic. That order remained until changed during the eradication campaign. It was the first move towards better control in the Northern Territory.

At the end of the War Colonel A L Rose was appointed Chief Veterinary Officer and the Animal Industry Branch, which paralleled the disease control service in the other States, was set up in 1946. Rose had long experience with pleuropneumonia in New South Wales and immediately set out improving control especially in travelling cattle. Outbreaks in travelling cattle were monitored and if necessary mobs were held up and re-vaccinated.

In Queensland in 1945 the Department of Agriculture and Stock was reorganised, and the disease control service was decentralised into five divisions each under a divisional veterinary officer with district inspectors and inspectors of stock under their control.

These developments marked the beginning of remarkable advances in disease control in northern Australia. Pleuropneumonia was the first major disease to be tackled.

A decade of decisions (1950-1960)

A number of significant events in the decade from 1950 to 1960 led to developments which culminated in a decision to eradicate pleuropneumonia.

First, a succession of heavy wet seasons from 1949 to 1951 in northern Australia greatly increased the numbers of cattle turned off and inevitably brought an increase in outbreaks, most of them in mobs from the Northern Territory and the Gulf. In 1950 nearly all stock districts in Queensland became infected. To deal with the problem the Chief Inspector made vaccination of cattle travelling into and through Queensland’s endemic, areas compulsory.

Investigations in travelling mobs in mid-1951 quickly showed two problems. The first was inefficient vaccination due to faults with both methods and materials. These were corrected relatively easily with supervised vaccination. The second problem was the holding together of cattle for some days or even weeks while mobs were assembled. As mobs were not vaccinated until they were about to travel, susceptible cattle could become infected in the interim. The answer to this was herd vaccination, but the difficulty was how to persuade owners to do it when they saw no need for it.

To overcome the latter problem in Queensland inspectors were trained in extension procedures and began work in the northern endemic area. They used information from all sources, but especially from abattoirs, to identify infected stations. These were visited and the advantages of vaccination pressed home. The response was good; vaccine distributed increased from 340 000 doses in 1951-52 to 600 000 doses in 1955-56. By 1958 some 800 stations had been visited, some of them three or four times. Outbreaks fell sharply; the last occurring in 1960.

The next stage in Queensland was the creation of a protected area in the south-east of the State where most of the dairy herds were located. This occurred in 1960 when the area east of a line from Rockhampton through Wandoan to Bonshaw on the New South Wales border was given protected status and to enter it cattle had to meet certain conditions.

The second major development occurred in unexpected circumstances with outbreaks in South Australia’s agricultural districts in 1951. On investigation the Chief Inspector found that the conditions laid down in 1932 for grazing permits had been ignored. He warned that firm action would be taken if further breaches occurred. When outbreaks occurred in 1952, the conditions were enforced and owners from Central Australia were penalised when prices fell as a consequence. Representations were immediately made to the Premier of South Australia by the Centralian Pastoralists Association.

The third major event involved New South Wales and Victoria. Carrier animals from Queensland in 1952 started the worst epidemic in New South Wales for 20 years. Infected cattle also reached Victoria where the situation was even worse — farms over almost the entire State were involved. Industry organisations in both States pressed angrily for action to prevent a recurrence.

In 1958 the Standing Committee on Agriculture appointed a Sub-committee for the control and eradication of pleuropneumonia and in 1959 it made recommendations in respect of several proposed areas:

•   in the Kimberley and Victoria River district, more information on the distribution and prevalence of the disease should be obtained, initially from abattoirs

•   in the Darwin-Gulf area, extension work and vaccination of travelling stock should continue

•   in the Barkly Tableland district additional staff and resources should be made available to expedite extension work and vaccination

•   the Gulf area of Queensland was seen as critical to eradication elsewhere in that State.

Compulsion should be resorted to, if necessary, to achieve co-operation, and additional staff and resources should be provided to enable additional areas to be given protected status as soon as possible.

Eradication

The field campaign began in Queensland in 1961 with six additional inspectors and a senior veterinarian in charge. It was an intensification of the earlier program. Vaccination was increased. In certain years more than one million cattle were vaccinated. Abattoir surveillance was increased to uncover every possible focus of infection; each year from 1961 to 1966, more than a quarter of a million lungs, mainly from northern and western cattle, were examined. M mycoides was isolated from 11 lesions only and five others returned a positive precipitin test result, all before 1965. Many CF tests were done on slaughter cattle, initially as a check on visual examination of lungs, but these placed a heavy burden on the laboratories and from 1965 only selected lots were tested. No evidence of the disease was found in 1965 and 1966 but in 1967 M mycoides was cultured from chronic lesions in single slaughter cattle from three stations in Cape York Peninsula. The precise origin of one was not determined, but follow-up tests on the other properties did not disclose infection. As the herds had been vaccinated a little earlier the possibility that the lesions were caused by the vaccine could not be discounted. This was the last evidence of the disease in Queensland — a decade of vaccination had achieved its purpose.

In the Northern Territory, a veterinary officer and four stock inspectors began operations in the Barkly Tableland district in 1961 and the next year there were six inspectors. Some pastoralists had vaccinated whole herds or animals at branding for some time. Vaccination was now supervised and some 30 000 were done under supervision each year. In 1963, the Chief Veterinary Officer, G A Letts suggested to the Sub-committee that as no evidence of pleuropneumonia had been seen in the Barkly District for four years and there had been two years of good vaccination cover, protected area status should be considered but with vaccination continuing. Similar status should be considered for the Katherine-Darwin area as the disease had not been seen there for six years and no evidence of it was found in some 11 000 cattle slaughtered at each of the new abattoirs established at Darwin and Katherine in 1963. The Sub-committee agreed and, after intensive ground and air surveys to check on cattle and boundaries, the Barkly and Katherine-Darwin Protected Areas were created in 1964. Only the Victoria River District remained infected. It had a notorious reputation for the disease and clinical cases were still seen in travelling and resident cattle in 1963. Two inspectors were stationed there in that year to assist with vaccination and in 1964 a veterinary officer was placed in Katherine to supervise abattoir and field activities. By 1967 about 75 per cent of cattle in the district had been vaccinated. Although old lesions in individual slaughter cattle were found in 1965 only one farm, Legune was of real concern. It adjoined Carlton Hill in Western Australia. Both were in the same ownership and were heavily infected. An intensive vaccination program from 1965 resulted in rapid regression of the disease and in 1967 only three sequestra were found in 600 slaughter cattle from Legune and five in more than 1100 from Carlton Hill. In his 1967-1968 Annual Report the Chief Veterinary Officer R W Gee wrote ‘in the whole of this year and in the previous six months no active cases were recorded in the field, abattoirs or quarantine properties’.

No action had been taken in the Kimberley region until 1963. Surveys were commenced then and the vaccination program began in earnest in 1964 with two inspectors supervising vaccination of young stock at branding. Surveys had shown 13 stations in East Kimberley to be infected. J Armstrong, a senior veterinary officer, was stationed at Kununurra in 1965 and rapid progress was made from that time. About half of the 200 000 cattle in the area had been vaccinated at the close of the 1966 season.

Inspection of slaughter cattle over several years had not disclosed the disease on any West Kimberley station, and it was proclaimed a protected area in 1966. Armstrong had made a traverse through the Drysdale River area in 1966. He found few cattle and no sign of disease. Nor had there been any evidence of pleuropneumonia for more than nine years in the Halls Creek area so both were made protected areas in 1967. By 1968 nearly 14 000 Carlton Hill cattle had been vaccinated since 1964 and this was reflected in very satisfactory elimination of the disease. Although 23 lung lesions were found at slaughter in some 1100 cattle, comprehensive laboratory examination revealed only one fibrous pneumonia. A positive precipitin test resulted but no pleuropneumonia organisms were cultured. Apart from Carlton Hill and Legune where only old resolving lung lesions were noted there was no evidence of pleuropneumonia anywhere in Australia in 1968.

Up to that time each State had determined its own criteria for movement within its own borders and some anomalies were apparent. So the Sub-committee called a meeting and divided the continent into three categories. Areas free from the disease were given Class 1 status; protected areas, Class 2; and infected areas Class 3. Uniform