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This article was published in 1962
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.

Contagious Bovine Pleuro-Pneumonia

CONTROL IN QUEENSLAND

R.S. STRANGER, B.V.Sc., Divisional Veterinary Officer, Townsville

Contrary to popular belief, Contagious Bovine Pleuro-pneumonia is not widespread in Queensland. However, there still are regions in which the disease is enzootic, such as:—

1. The Gulf Areas.
2. The Lower Peninsula Areas.
3. The Channel Country.
4. The North Coast Hinterland.

Even in these areas it is not widespread, but restricted to scattered pockets of infection.

Control measures have varied over the years, but during the last 10 years they have hinged on vaccination programmes. Outbreaks in travelling stock are now very rare indeed, due to enforced inoculations prior to travel.

The following table indicates how the increasing use of V5 Strain vaccine has had a profound effect in reducing the incidence of C.B.P.P.

Year	Number of Doses of C.P.P. Vaccine Distributed in Qld.	Number of Outbreaks
1951-52	345,700	45
1952-53	375,050	21
1953-54	392,228	13
1954-55	393,875	7
1955-86	605,400	10
1956-57	663,675	10
1957-58	625,000	2
1958-59	509,000	3

The big "smashes" that once were a feature of many outbreaks, and involving up to 10 per cent. and 15 per cent. of affected mobs, are a thing of the past.

These results are important in that the chances of introducing the disease to free areas have been reduced markedly, even though not eliminated.

In Queensland, C.B.P.P. control can be divided into the follow ing categories:—

1. Control of active outbreaks; leading to complete elimination.
2. General preventive control in the enzootic areas.
3. Eradication.

CONTROL OF ACTIVE OUTBREAKS

Control of active outbreaks varies according to the size of the property and type of management. Properties within the Protected Area are either small, beef cattle holdings or dairy farms. Properties are well improved and effective control of the whole herd can be exercised, with the result that "clean" musters are the rule rather than the exception.

Generally speaking, the following routine, with some variations depending on circumstances, is adopted:—

1. Confirmation of diagnosis by submission of samples to the laboratory. However, if the investigating officer is satisfied as to the diagnosis, he institutes quarantine proceedings immediately. All in contact properties are made a buffer area and "stand-still" orders issued.
2. All clinical cases are destroyed.
3. Cattle on the affected property are then blood sampled for the C.F. test, and inoculated. Any further active cases are destroyed when signs of pleuro-pneumonia manifest themselves.
4. All reactors to the C.F, test are forwarded to meatworks for slaughter.
5. Cattle on all in-contact properties are inoculated, and are only permitted out of the buffer area subsequent to an inspection which reveals no clinical cases to be present.
6. An effort is made to trace the origin of the cattle responsible for the outbreak, and the history of any recently introduced stock is investigated. Properties on which stock have had contact with such infected mobs are quarantined, blood sampled for C.F. testing, or inoculated.
7. Quarantine restrictions may be lifted not less than six months after the appearance of the last active case, but not before the herd has given two clean C.F. tests at an interval of 28 days.

In sparsely settled areas, elimination of C.B.P.P. after outbreaks is very difficult. On these properties cattle are run without any effective means of control because of:—

(a) The large areas of the holdings (up to 4,000 square miles). Stocking rate varies from five to eight beasts per square mile up to 10 to 15 beasts per square mile.

(b) Lack of improvements such as fences and yards. In areas such as the far South-West of Queensland, handling of cattle is rarely carried out and, when done, broncho yards are used. No crush work is done in this area. In other areas crushes are available because of necessary tick treatment. In most of the enzootic areas, however, clean musters are impossible to effect.

Generally speaking, control measures in these circumstances involve:—

1. Confirmation of diagnosis.

2. Quarantine.

3. Vaccination in some cases.

4. Destruction of clinical cases.

5. Frequent inspections.

6. Release from quarantine six months after the appearance of the last clinical case, subject to an inspection revealing no further clinical cases.

TRAVELLING STOCK

Methods of control vary according to circumstances.

FAT CATTLE

Clinical cases are destroyed. Providing there is no chance of contact with other cattle along the route they are following the mob is allowed to proceed to the nearest rail-head for trucking to meatworks for immediate slaughter.

Vaccination may be enforced, depending on the distance from the meatworks.

STORE CATTLE

Control measures depend on:—

(a) Distance from destination or rail-head. If they are nearing their destination they are allowed to proceed, and the recipient property is then quarantined. If near a rail-head, they may be permitted to proceed to the recipient property by rail, and again the property of destination is quarantined. In either case, re-inoculation at the first available yards may be enforced.

(b) If the mob is a considerable distance from a rail-head or their destination, quarantine restrictions depend on feed and water supply. Generally speaking, re-inoculation at the first available yards is enforced. Restrictions are lifted after a period free from the appearance of clinical cases, and subject to inspection.

Circumstances often occur in which sampling for C.F. testing and re-inoculation cannot be carried out.

PREVENTIVE CONTROL WITHIN THE ENZOOTIC AREA

This is partly regulatory and partly voluntary.

Regulatory

This applies to travelling cattle mainly. During the past 10 years cattle were permitted to travel through, or from, the enzootic area, subject to inoculation. This inoculation has been carried out by owners, or agents, and in many cases by Department officers.

In addition, any fat cattle which were on the road more than 28 days between the property of origin and rail-head were required to be inoculated prior to travel.

This compulsory vaccination has been very effective in reducing the number of outbreaks in travelling stock in Queensland. As a matter of fact, there has not been a reported outbreak in travelling stock in Queensland for some years. However, outbreaks can occur due to chronic carriers becoming active cases following breakdown of sequestrated lesions.

Voluntary

The voluntary side of C.B.P.P. control is attended to by extension officers who are specially trained Stock Inspectors of the Department, Up to, and including, 1960, four of these officers were seconded for this type of work. Their main aim was to visit each property within the enzootic area, with a view to inducing the management to institute a programme of preventive inoculations. Generally, bi-annual inoculation of the whole herd was advised; or inoculation of weaners into the weaner paddock; or vaccination of all calves over the age of four months.

These men concentrated on properties where meatworks' examinations indicated that the disease was smouldering. Commonwealth Inspectors at meatworks forwarded monthly reports of the numbers of active cases, sequestra, and adhesions in the various mobs. Armed with this information, it then became the task of the extension officer to induce these people to inoculate their herds.

ERADICATION

1961 was the inaugural year of the National Bovine Pleuropneumonia Control and Eradication Project.

The immediate aims of the campaign are:—

1. To extend the Free Area northwards along the coast and Westwards to the Barrier Fence and, later on, to the Channel Country. The Alpha-Springsure area is the first region destined for eradication.

2. To supervise the inoculation of all store cattle travelling from, or through, the enzootic area. Prior to 1961, inoculation of travelling mobs was left to the owners or managers. By this supervision, we can be sure that a greater percentage of travelling stock is inoculated effectively.

3. To intensify extension activities, especially in the Gulf and Peninsula Areas.

4. To intensify follow-up extension visits to properties where meatworks' returns indicate that Pleuro. is smouldering. A further step forward was taken at meatworks, in that samples were taken of all active cases and sequestra, and forwarded to the laboratory for culture, C.F. and precipitin tests.

5. To experiment with crush-side tests in the field.

With regard to the Alpha-Springsure Area, all lungs from this region were palpated for evidence of C.B.P.P. by men especially appointed to carry out this work. In addition, blood samples were collected from all cattle from this area slaughtered during the killing season.

Results

1. No active cases, or sequestra, were found at slaughter.

2. Of nearly 3,500 sera collected only one was positive to the C.F. test. The animal from which this sample was taken had normal lungs. The only inference from this is that the animal was a vaccinate, or had had some contact previously with C.B.P.P. However, the whole herd was subsequently blood sampled, and all samples were negative to the C.F. test.

With regard to the scheme on a State-wide basis, 165,000 store cattle were inoculated during the five months it was in progress of these, 135,000 were supervised by departmental officers. The 20 per cent. not inoculated under supervision involved mobs where supervision would have entailed unjustifiable delay, or originated from poorly accessible properties which involved considerable travelling distance.

Meatworks' Findings

Of approximately 300,000 animals slaughtered at northern meatworks, seven suspect active cases were discovered, together with 46 sequestrum-like lesions. Only one active case was confirmed in the laboratory, while only two sequestra were found to be viable. Properties from which viable lesions were found were placed in quarantine. In the Protected Area, quarantine will be dealt with as discussed earlier, but in the sparsely settled areas an inoculation programme will be insisted upon prior to lifting of quarantine restrictions.

Approximately 3,000 adhesions (1 per cent.) were found. Properties with a high incidence of adhesions all had histories of C.B.P.P. outbreaks. Many of them have had inoculation programmes in progress for some years.

Extension: Voluntary Control

Prior to 1961, 146 properties had inoculation programmes in progress.

During 1961, 811 properties were visited by Extension Officers and, as a result, 79 holdings began an inoculating programme. Most of those 79 were in the S.E. Zone of the Enzootic Area, which is destined for inclusion in the Protected Area in the near future.