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Chlamydiosis in Sheep & Cattle

JB Kemp BVSc, Dip AH, MSc, Veterinary Inspector, Pastures Protection Board, Forbes, NSW, 2871

Contents

Summary

Introduction

Classification of Chlamydia

Characteristics

Stability and inactivation of Chlamydia

Chlamydia and infection

Serotypes

Chlamydial infections in sheep

1. Intestinal infections

2. Respiratory infections

3. Chlamydial abortions in ewes

4. Polyarthritis in lambs

Chlamydiosis in lambs in N.S.W.

1. Report in Veterinary Notes, July 1965

2. Report by Regional Veterinary Laboratory Orange, 1981

3. Report by Regional Veterinary Laboratory, Orange. 1982.

Chlamydiosis in lambs in the Forbes Pastures Protection District

1. Property A

2. Property B

Serological investigations at Cowra Agricultural Research Station (Seaman. 1983)

Chlamydial Disease concerning both sheep and cattle

Sporadic Bovine Encephalomyelitis on a Forbes Pastures Protection District property

Isolation of Chlamydia psittaci from an aborted bovine focus on a Forbes district property

Discussion

Conclusions

Acknowledgements

References.

Introduction

Chlamydiosis in cattle (Sporadic Bovine Encephalomyelitis) is not uncommon in the Forbes Pastures Protection District. However, reports of Chlamydiosis in sheep are uncommon. Investigation into this disease on three properties is reported here - two on sheep properties and one on a small cattle herd.

Classifictaion of chlamydia

Chlamydia are considered to be a distinct group of micro-organisms, placed in the Order Chlamydiales with only one genus Chlamydia. There are two species recognised (a) C. trachomatis, most strains of which affect only man, and (b) C. psittaci, which represents most of the strains affecting birds and domestic mammals.

Characteristics of Chlamydia

Like viruses, Chlamydia are obligate intracellular parasites. However, Chlamydia resemble bacteria in the composition of the cell wall, and in the possession of both RNA and DNA, and in multiplication by binary fission. Unlike bacteria, replication of Chlamydia occurs only within host cells, similar to viruses, and they can only be propagated in cell cultures, chicken embryos, or laboratory animals. (PE Shewen, - Canadian Vet. J. 21 : 2-11).

The development cycle involves small infectious forms known as elementary bodies (250-450 nm) which are phagocytosed by host cells and develop within the cytoplasm of these cells. The elementary bodies are reorganised into larger reticulate bodies (approximately 1000 nm,i.e. iu) which are non-infectious. These grow and multiply by binary fission. These then undergo a second process of reorganisation which involves intermediate forms that become elementary bodies. Then the cells that contain them rupture discharging showers of infective elementary bodies into the tissue fluids. (J Seaman, 1982)

Stability and inactiviation of chlamydial agents

Chlamydia are among the less stable micro-organisms. They are susceptible to heat. Heating at 56°C destroys infectivity within minutes. Under laboratory conditions, infectivity of most strains is lost rapidly at 37°C. However, one worker found that Chlamydia isolation from pigeons retained infectivity over a 24 hour period at 43°C, but a turkey isolate was completely inactivated during this period.

Chlamydia are susceptible to bacterial agents in general use and contact with 0.1% formalin and 0.5% phenol destroys infectivity within minutes. However, it was found that chlamydial infectivity persisted for 2 to 3 days in tap water at room temperature.

Infectivity can be preserved by storage at -70°C or lower temperatures, although some decrease in infectivity occurs on initial freezing. (Graham 1976)

Chlamydia and infection

Chlamydia psittaci is responsible for a variety of disease syndromes in animals. The organism does not appear to be very host or tissue specific. (Shewen 1980)

Exceptionally, some animals may experience severe or even fatal disease as a result of chlamydia exposure. A well balanced host-parasite relationship represents the common nature of chlamydial infection. This long-lasting inapparent or "latent" state has been documented in several species - birds, cattle, guinea pigs, sheep and man. In some cases chlamydia are excreted by the latently infected host; in other cases the organisms would be maintained in a non-infectious form. Under circumstances of stress, "carrier" animals may shed organisms in large numbers or may in fact lapse into clinical disease.

The intestinal tract is the natural habitat for chlamydiae. Inapparent enteric infections are common in ruminants and most avian species. Faecal shedding may be the most important mode of transmission. Chlamydial organisms have been isolated in the faeces of normal cattle, sheep and goats. Up to 60% of the animals in a particular herd may shed organisms for several years. The epidemiological significance of this is undetermined.

The route of transmission of Chlamydial organisms and the pathogenesis of the systemic disease are not well understood. The primary site of entry seems in general to be any mucous surface, eg. digestive tract, respiratory tract or conjunctiva, so that the common routes of infection are thought to be ingestion or aerosol. After entry of the organism into the body, a chlamydaemia develops with infection or parenchymatous tissues - liver, kidney, heart, lung and brain. The chlamydial organisms parasitise and multiply in cells of the host's reticulo-endothelial system and in various epithelial cells with the primary lesion being related to the vascular system. Later persistent infection may be established in one or more organ systems,e.g.joints, resulting in polyarthritis, and placenta resulting in abortion. (J Seaman, 1982)

A large number of strains of C. psittaci are recognised but it is not possible to consistently relate certain strains with specific diseases. Two distinct chlamydial serotypes have been demonstrated in sheep:-

Type 1 isolated from abortion, pneumonia and enteric infections, and

Type 2 associated with polyarthritis, encephalitis, and conjunctivitis.

These two groups do not cross react with each other or with avian isolates. However, the diagnostic serological test, the CFT, detects reaction to a group antigen, and such all strains are indistinguishable. In experimental infections. the route of infection largely determines the disease syndrome produced with certain strains capable of different clinical syndromes depending on the route of administration. (J Seaman, 1982)

Chlamydial infections in sheep

(1) Chlamydial Intestinal Infections

It is doubtful that the organism could be regarded as a significant cause of enteritis even though Chlamydia have been isolated from the faeces of healthy and diseased sheep in Australia. It is presumed that the intestinal tract may be a reservoir of these organisms, since the majority of sheep excreting chlamydia in their faces are clinically normal. (J Seaman, 1982)

(2) Chlamydial Respiratory Infections

Overseas reports detail experimental reproduction of pneumonia following chlamydia inoculation but evidence that this occurs as a natural event is rather weak. Most pneumonias from which chlamydia have been isolated have also involved other potential pathogens. (J Seaman. 1982)

(3) Chlamydial Abortion in Ewes

John Seaman (1983) reported Chlamydia isolation from abortion in sheep from two different flocks in N.S.W. This report confirmed earlier records (Rofe 1967; Hughes 1968) of chlamydial abortion in Australia. Seaman commented that evidence from these episodes and that from previous surveys indicate that in contrast to many other countries, the prevalence of Chlamydial abortion in sheep in Australia is low.

(4) Polyarthritis of Lambs

Polyarthritis usually affects lambs up to six months of age but has also been recorded in older sheep Seaman (1982) states that morbidity is high (50%) especially in larger rapidly growing lambs, but mortality is less than 1%. The disease is characterised by fever, stiffness, lameness, anorexia, illthriftiness, and frequently conjunctivitis. In the early stages the animal may appear stiff and most animals will "warm out" of their stiffness with forced exercise.

The ocular lesions develop from conjunctival hyperaemia, with excess clear lachrymal discharge, through follicular conjunctivitis, with discharge, becoming mucoid to purulent, to more advanced disease, probably enhanced by secondary infection, where there is extension to the cornea with oedema, vascularisation and keratitis. (Littlejohns. 1976)

The polyarthritis may involve all limbs or even the whole body. In the early stages the clinical appearance is of a generally stiff and rheumatic animal and it may be difficult or impossible to identify local areas or particular joints affected. Localisation in joints results in inflammation of the synovial membrane with extension to the joint capsule. Tendon sheaths and synovial sacs may be similarly affected.

The joint lesion is non-suppurative and progresses through predictable stages of oedema, hyperaemia and some necrosis, with excess fibrinous fluid, to more chronic stages of proliferation, thickening and contraction of periarticular tissues. Deformation is a result of these changes and there is not involvement of bone or articular cartilage.

There is some reason to suspect that the nutritional state may be one factor having a bearing on the degree to which arthritic involvement develops. On at least two occasions this form of disease has been investigated where there have been essentially similar lambs on irrigated and dry pastures on the one property on each occasion serological tests indicated a comparable incidence of chlamydial infection in the two groups, but polyarthritis was only evident in the lambs on irrigated pasture. The suggestion would be that the more rapidly growing tissues of the lambs on a higher plane of nutrition may be more susceptible to show disease due to chlamydial infection.

Minor histological lesions of inflammation and cell infiltration may be demonstrable in brain, liver, kidney, and lung during the systemic phase of the disease.

The mortality rate is usually low and the main economic loss is due to loss of production. Affected sheep are restricted in their mobility for grazing and either lose weight or fail to make normal gains. It also seems likely that animals which suffer sub-clinical disease may have their growth rate reduced. (Littlejohns. 1976)

Chlamydial polyarthritis in lambs NSW (Jackson 1965)

Jackson (1965) states that in some areas of N.S.W. in recent years a form of polyarthritis has been seen in crossbred lambs, unassociated with any obvious predisposing cause and from which no causal bacteria could be isolated.

In July, 1963, elementary bodies resembling those of a PLGV (Psittacosis lymphogranuloma venerun) type organism (ie. Chlamydia) were seen in joint smears prepared from a lamb received from the Orange district. Again, in July 1964, specimens and later a live lamb were received from a property in the Gilgandra district which had experienced lameness in lambs over many years.

Infective material was inoculated into four crossbred lambs which produced the disease as seen in the field. Fever was noticed after three days, lameness after 6 to 9 days, and recovery after 20 days. C.F. antibodies were detected in high titre in the first four lambs eight days after inoculation, had started to decline at 26 days and had reached quite low levels by eight weeks. They were negative prior to investigation.

The condition is most commonly see in crossbred lambs in good condition from 8 to 14 weeks of age but sheep of almost any age may be affected. Morbidity is variable, often low but with occasional incidences of up to 80%. The mortality is practically nil. Recovery probably occurs in 1 to 2 weeks. Economic loss is related to the loss of blood or condition in fattening lambs.

There is little or no palpable abnormality detected in the joints and post-mortem findings are unspectacular. Synovial fluid in practically all joints, sheaths and bursa is increased and discoloured but no obviously so. The presence of fibrin plaques in the joints is fairly constant.

Interlaboratory Monthly Report - Regional Veterinary Laboratory Orange. October 1981

Chlamydia, presumably psittaci were isolated from five cases during August - October 1981.

1. Ovine abortion - isolated from foetal stomach and pool of liver and lung.

2. Ovine abortion - isolated from cotyledon.

3. Ovine polyarthritis / Chlamydiosis - isolated from blood of 3 lambs.

4. S.B.E. (Sporadic Bovine Encephalomyelitis) - isolated from brain of calf.

5. S.B.E. - isolated from blood of steer.

The comment was made that this region appears to have significant chlamydial disease problems. (Webb, 1981)

1982

Throughout 1982, the Regional Veterinary Laboratory, Orange, received 13 diagnostic submissions related to chlamydia diseases in sheep. The condition was confirmed serologically on nine occasions and by isolation of chlamydia organisms on two occasions. (Seaman, 1983)

Chlamydiosis in lambs

Forbes Pastures Protection District

Property A

The first visit was made to this property on 23 June 1982. The disease occurred in a mob of 330 crossbred lambs (February to March 1982 drop.i.e.. 3 to 4 months of age). Clinical signs first showed up near the end of March (ie. 2 days after a heavy fall of rain). Six lambs died since the start of clinical signs. Nine lambs were first seen affected, then more were affected at the beginning of April.

Since 19 and 20 June 1982, a large number of lambs have been affected. On 23 June 1982, 32 lambs were showing clinical signs.

Age of affected lambs was two weeks to four months.

Lambs in another mob of 220 were showing mild clinical signs.

The lambs had been on lucerne since they were born. The area is not irrigated, but there is a lot of seepage due to a high water table.

The owner buys in first cross ewes as two tooths (Border Leicester cross) and are mated on the place with Dorset rams.

Sporadic Bovine Encephalomyelitis (S.B.E.) was diagnosed in a mob of steers from the same area about the end of 1980 on this property. No cattle have been run on the property since that time.

Clinical signs

Affected lambs show a rapid loss of condition within a few days of being affected. Lambs show lameness - some lambs hold a leg up when walking, stiffness when walking, ocular discharge, and an increased temperature (up to 41.1°C).

Post-mortem

Very little was seen at post-mortem. Kidneys were pale.

Laboratory results

Bacteriology - negative for liver, kidney, spleen and mesenteric lymph node.

Culture of bloods for Chlamydia not done due to lack of embryonating hen eggs.

Histopathology

Brain - mild non suppurative encephalitis.

Liver - mild degenerative changes of parenchyma.

Kidney - generalised increase in nononuclear and polymorph inflammatory cells beneath renal pelvis epithelium

Blood test for chlamydia - 14. lambs tested on 23 June 1982

3 negatives

3 CFTs of 10

4 CFTs of 20

2 CFTs of 40

2 CFTs of 80

Laboratory diagnosis - Chlamydial polyarthritis.

Also two live lambs submitted on 24 June 1982, to Regional Veterinary Laboratory, Orange

Lamb 1 post-mortemed (SA ON 82/1168 - 24/6/82)

Slight distention of left carpus and right stifle with an increased volume of joint fluid. The joint appeared normal. Severely inflamed conjunctivae in both eyes. Both kidneys had small (1 mm) white focal lesions in the cortices.

Bacteriology - negative.

Chlamydia isolated from pooled tissues from lamb post-mortemed (1) and from blood of lamb (2) collected 24 June 1982 - but not four later bleeds up to 12 July 1982.

Temperatures of lambs

Both febrile 40.4°C.

(Ear tag 455) Sample 1 - CFT of 40 to Chlamydia

(Ear tag 456) Sample 2 - CFT of 10 to Chlamydia

Histopathology

Liver - mild diffuse degenerative changes and moderate accumulations of mononuclear inflammatory cells.

Kidney - moderately severe focal subacute to chronic interstitial nephritis.

Heart - mild focal non-suppurative myocarditis.

Brain -mild focal non suppurative encephalitis, more severe in brain stem.

Diagnosis - Chlamydiosis.

Lamb 2 (submitted to the Laboratory on 24 June 1982). SA ON 82/1168

This lamb was bled every two days for serology and chlamydial culture.

Results of culture of chlamydia -

Culture positive on blood collected 24 June 1982 but negative on bloods collected on four occasions from 28 June 1982 to 12 July 1982.

Second visit on 7 July 1982 (two weeks after the first visit on 23 June 1982).

Nine of the 14 lambs tested on 23 June 1982 were retested.

The owner treated the original group of 32 sick lambs with Terramycin L.A. Those showing early signs showed good response three days after treatment.

Nine new cases occurred in the mob since the first visit.

Another four lambs were affected in a new mob of 180 crossbred lands (unweaned).

Results of Blood Tests

	* * * * * * DATE OF TEST * * * * *
EAR TAG NO	23/6/82 CFT titre (14 tested)	8/7/82 (15 days later) CFT titre (10 tested)
931454	10	20
455	40	to lab. (Pmd 24/6/82)
456	10	to lab.
457	80	40
458	80	20
459	20	40
460	20	40
461	-ve	-ve
462	20	20
463	40	80
464	10	40
465	-ve	lost ear tag
466	-ve	lost ear tag
467	not tested	20 new case
P.M. lamb (23/6/82)	20	Temp. 40.3°C

* 14 tested on 23/6/82

* 10 tested on 8/7/82 - 15 days later

* mothers mixed ages and lambs up to 4 months of age)

Owner seen on 29 October 1982

39 of the original group of affected lambs came right with treatment, but 3 to 4 kept getting the disease every 2 to 3 weeks till August (ie for two months since the first visit in June).

The lambs were fattened and sold out by September.

536 lambs, first cross, 2 and a half to 3 months of age, were bought at the end of September 1982, from the saleyards. Within one week of coming onto the property, One lamb had severe clinical signs of chlamydiosis and within two weeks of coming onto the property, three more lambs were affected. The lands were not treated.

In another mob that landed later, 3 were affected, 2 and a half to 3 months of age. These 5 lambs were isolated and not treated.

Visit on 9 November 1982

The owner has had a continual problem with the lambs showing symptoms of Chlamydiosis. Recently six were seen in a mob showing signs. These were from the owner's own mob. The ewes are of mixed ages as they are continually split. Affected lambs are 2 weeks to 4 months of age. There are 300 to 400 in the mob.

21 lambs tested on 9 November 1982 (SA form ON 82/2302)

Two of these showed high temperatures and acute symptoms. Two others were noted as having an eye discharge and two others noted as having swelling of the joints. The 19 not showing acute signs were those previously affected.

Visit on 16 November 1982

17 lambs bled.

9 of those appeared normal.

2 not bled on 9 November 1982 were sick and had temperatures (39.9°C and 40.4°c), another was sick and the remainder had eye discharges.

2 lambs were submitted to the Regional Veterinary Laboratory, Orange.

	* * * * DATE OF TEST * * * *
EAR TAG NO	9/11/82	16/11/82
929776	-ve	-ve
777	-ve	-ve
778	-ve	-ve (crusty eyes)
779	-ve
780	-ve	-ve
781	-ve	-ve
782	-ve	20
783	10	-ve (crusty eyes)
784	80	40
785	10	-ve
786	20	10
787	160	80 (watery eyes)
788	-ve	80
789	-ve (temp. 41.1°C stiff)	40
790	20
791	-ve
792	40
793	-ve (stiff)	-ve
794*	160 (temp. 40.5°C stiff)	80 (tucked up, illthrifty red eyes)
795	20
796	10
756	not bled	160 (t. 39.9°C)
757*	not bled	80 (t. 40.4°C. tucked up, lame)

* Ear tags 794 and 757 brought back to Orange Laboratory

Results of tests on the 2 lambs submitted to the Regional Veterinary Laboratory, Orange, on 16 November 1982

	SEROLOGY TITRE		CHLAMYDIA CULTURE
DATE BLED	Lamb 757	Lamb 794	Lamb 757	Lamb 794
9/11/82	not bled	160
16/11/82	80	80
18/11/82	160	160	-ve	+ve eyes
22/11/82	80	80	+ve eyes	+ve eyes
24/11/82	80	160
26/11/82	80	80
30/11/82	40	160
3/12/82	40	160
7/12/82	40	80	-ve	-ve
10/12/82	40	160
14/12/82	20	40
17/12/82	20	20
22/12/82	10	20
5/1/83	-ve	10
11/1/83		-ve
9/2/83		10
16/2/83		10 (post-mortemed 16/6/83)

The lambs were bled approximately twice weekly over an 8 week period at the Laboratory (John Seaman) and eye swabs taken on three occasions for Chlamydia isolation.

The titre of lamb 757 showed a maximum on 18 November 1982 and then gradually declined to negative within the next 50 days.

Lamb 794 showed a fluctuation in titre between 80 and 160 for the first 30 days, then gradually declined to a titre of 10 on 5 January 1983.

Culture results - eye swabs were taken on three occasions. Culture was positive from lamb 794 on 18 November 1982 and from both lambs on 22 November 1932 from eye swabs. Results were negative on 7 December 1982.

On 11 January 1983, the lambs were doing well.

These 2 lambs were run with 5 crossbred lambs to see if they would become infected. Up to 11 January 1983, the 5 other lambs showed no sign of disease or titres.

On 13 December 1982 owner advised -

Four lambs were affected out of a mob of 150 lambs, 2 months of age (crossbred lambs) and weaned approximately 7 days before (ie affected after stress).

On 14 January 1983 owner advised -

There were 12 more new cases in lambs, 3 months of age, crossbreds, weaned 3 weeks previously and clinical signs seen within 7 days of weaning. These lambs had no contact with the previous cases.

13 January 1983 visit made to the property

7 lambs brought back to Regional Veterinary Laboratory. Orange.

18 January 1983 (from mob reported on 14 January 1983).

7 lambs brought back to Orange from owner's property. Crossbred lambs, 3 months old, weaned 3 weeks ago. Last week 12 developed sudden onset of lameness and unthriftiness.

SAMPLE NO.	SIGNS (SA ON 83/0117)	TITRE
42	Slight watery eye discharge, slightly tucked up	20
43	Tucked up, crusty eyes	-
44	Tucked up, crusty eyes, slightly watery discharge	160
45	Lame, eyes OK	20
46	Acute case picked out by owner, red conjunctivae, watery, crusty eyes	10
47	Eyes red, very crusty	40
48	Eyes OK. Severe arthritis older sheep	10

Project on Chlamydial Disease in Sheep at Agricultural Research and Veterinary Centre, Orange

Serological and cultural examinations confirmed a chlamydial polyarthritis syndrome on the Forbes property and on a Geurie Property.

A total of 12 weaner lands were purchased (7 from Forbes for detailed pathological examinations. Nine of those lambs with positive titres were autopsied and histopath and cultural examinations undertaken.

Post-mortems

Lesions found in kidneys of all lambs with a chronic interstitial nephritis and suppurative pyelonephritis being a consistent finding.

A focal non-suppurative interstitial myocarditis was found in 6 of 9 lambs.

Mild focal non-suppurative encephalitis was found in 3 of 9 lambs.

Variable pathological changes were present in conjunctivae, joint capsule, lungs and liver.

Culture

Selected tissues from these lambs have been culture in embryonated hen eggs.

Chlamydia cultured from all tissues on two occasions and from eye swabs on two other occasions.

Remaining 5 lambs have been culture negative despite pathological lesions. It appears that the success of recovery of the chlamydia organism is related to the stage of the disease with a systemic (acute) phase early in the condition, progressing to localisation in conjunctiva, and finally disappearance of the organism with lesions remaining. (J Seaman, 1983a)

Contact with introduced lambs

Remaining 3 weaner lambs that were purchased were run with 5 normal lambs (introduced) of similar age to reproduce natural disease and monitor serological response. These lambs bled weekly for 5 months.

The original infected lambs

(previous titres of 160 and positive culture eye swabs) gave negative titres over an 8 week period.

Of the 5 introduced lambs, 4 developed titres (1 x 40, 1 x 20, and 2 x 10), but no obvious clinical disease.

Eye swabs from introduced lands

Positive culture from 2 lambs - both having negative titres at the time the positive swabs were taken and one being consistently negative over the 5 month period of bleeding.

1983

A lot of new cases showed up, estimated 50 to 60. in new season's lambs - age 2 weeks to 3 months, in several mobs (approximately 5 mobs from a total of 1500 first cross ewes). All were treated and none died. It went right through the winter and became less trouble with time.

1984

Approximately 29 lambs were affected from 6 weeks to 6 months of age - crossbred lambs from a mob of 300 lambs. They were born on the place from August to September and developed after weaning (weaned in October at 2 months of age). The disease also occurred before weaning after a cold snap. They were on lucerne, not irrigated, but there is a lot of seepage.

Once lambs get Chlamydiosis, it puts them back 1 to 2 months. It takes them from a fat salable lamb to a store lamb.

In the end, the owner didn't treat the lambs due to the time and cost of treatment of the lambs. He drafted out the affected lambs and disposed of them.

1985

Owner was seen on 2 February 1983. There has been no cases of Chlamydiosis for more than 12 months. The trouble has been only on two paddocks with access to a creek. They are now used for cropping and consist of 35 acres and 110 acres. The area has been under crop, but the sheep still go onto it. They graze the cereal crops and the stubble. The area is not irrigated but there is a lot of seepage due to a high water table. The lambs were on lucerne on these paddocks prior to the cropping and they drank from a creek (not flowing).

The disease occurs after a stress, eg. after a sudden change in weather (cold or wet). or after weaning (within 7 days). The ewes are of mixed ages and they are continually split.

On 26 August 1985, 26 rams were tested for Ovine Brucellosis and Chlamydiosis. 22 of these rams showed titres to Chlamydiosis (2 x 40, 3 x 20, and 17 x 10), but none was showing clinical signs of the disease.

Chlamydiosis in lambs

Forbes Pastures Protection District

Property B

A lamb was brought in on 30 April 1985 for post-mortem. Post-mortem showed a very severe pneumonia and pleurisy. At the Orange laboratory bacteriology culture of lung and thoracic fluid showed heavy mixed growths of Pasteurella multocida and Corynebacterium pyogenes. Cultures of liver, kidney and spleen showed mixed growths, mainly of C. pyogenes.

Histopathology of the kidney showed a moderately chronic interstitial nephritis. The laboratory commented (Chris Bourke) that these changes reflected the circulation of bacterial toxins generated by another organ.

Histopathology of the lung showed a chronic pneumonia, the lung showing large necrotic areas of suppuration.

History of the mob

There were 350 lambs in the mod. They were crossbred lambs, out of Merino by Border Leicester ewes by Dorset Horn rams. They were born from the start of February to the end of February, 1985. The lambs were marked with rubber rings about mid March. The lambs were weaned on 26 April 1985 (age: 2 months old).

The lambs were out of a mob of 310 crossbred ewes, full mouth, and had been on the property for about 3 years. They had been bought in as two tooths from Forbes Saleyards.

The ewe mob (mothers of the lambs) were on a dry block prior to lambing. When they started lambing the mob was put on lush irrigated lucerne and were left on it. They never had access to hay or dry feed. The irrigated area consists of 293 acres and is lucerne and is irrigated regularly. Irrigation is both flood and spray irrigation and the ground is wet when the sheep are put into the paddock.

The owner first noticed symptoms six weeks prior to the 1 May 1985,i.e.. approximately 20 March 1985. He first noticed the ewes dying with mastitis which he put down to the lambs not sucking them due to the stiffness of the lambs.

The first visit was made to the property on 1 May 1985. At least 12 lambs had died by this date and up to 40 lambs had been affected over the six week period up to 1 May 1985.

21 lambs were showing symptoms on 1 May 1985. Eight ewes had died in the mob from mastitis which the owner put down to the ewes not sucking.

The Veterinary Practitioner treated 5 lambs 3 weeks prior to 1 May 1985 with Oxytetracycline L.A. and all recovered except one suffering from pneumonia.

Approximately 30 other lambs were then treated with Penicillin by the owner which improved the lambs but did not cure them.

Clinical signs

Rapid loss of body weight, eye discharge, stiffness and lameness.

21 of the lambs showing clinical signs were separated out by the owner on 1 May 1985. Temperatures of 12 of these were taken and they ranged from 39.5°C to 41.3°C and averaged 40.5°C.

On 16 May 1985, over a 15 day period from 1 May 1985, 10 more lambs were injected with Terramycin L.A., which showed signs of lameness or runny eyes. The owner inspected the lambs daily and he found by treating the lambs immediately seeing the signs, that they were right the day following the injection and he couldn't tell the difference from the others. But if they are left longer, eg. 3 days, the bloom goes right off them, they lose weight, but the lameness goes.

Post-mortem of lamb on 23 May 1985

Tested for Chlamydia 1/5/85 CFT -ve

Tested for Chlamydia 23/5/85 CFT 10

Post-mortem

Showed pneumonia, kidneys showed changes in the cortex, joints in both front and back legs showed clear straw coloured fluid.

Laboratory results

Bacteriology - Cultures of Carpus, liver, kidney and spleen gave no visible growth. Culture of lung gave moderate, fixed growth including Pasteurella multocida.

Histopathology - kidney showed focal chronic interstitial nephritis. Lung showed diffuse chronic active broncho pneumonia with areas of abscessation. Liver showed diffuse, degenerative changes.

Chlamydial culture - results were negative.

Owner seen on 27 May 1985

The owner reported that there had been no more new cases for at least 10 days (and no lambs were given Terramycin injections over that period). The condition of 7 or 8 of the affected lambs had improved dramatically over the previous week and would be equivalent to the tops of the lambs in the other mob (ie. the lambs treated within the first 24 hours of sickness).

	= = = = = = = = DATE OF TEST = = = = = = = =
EAR TAG NO.	1/5/85	23/5/85	13/6/85	12/7/85	12/9/85
	18 tested	20 tested	10 tested	10 tested	11 tested
929671	40	40	10	10	20
672	10	10
673	40	40	20	-ve	10
674	40	20
675	-ve	40	40	20	20
676	-ve	10
677	10	20
678	40	40
679	10	20	20	10	10
680	-ve	10
681	10	10	-ve	-ve	10
682	10	10	10	-ve	10
683	80	40
684	20
685	40	20	20	10	20
686	20	20
687	20
688	-ve	10	10	10	10
No tag		10
No tag		40
No tag		10
No tag		10
689			-ve	-ve	-ve
690			10	-ve	10
931048					20

On 27 May 1985, 19 lambs temperatures taken - temperatures ranged from 39.4°C to 40.6°C with 40.1°C average.

11 lambs showed some signs of eye discharge. No lambs had been injected for at least 10 days.

Details of the blood tests

1/5/85 - 18 lambs tested - of the 21 showing clinical signs. Titres ranged from negative (4 lambs) to 80 (1 lamb). Cultures to chlamydia were negative (on bulked samples).

23/5/85 - 20 lambs tested. Titres ranged from 40 to 10 (no negatives). 1 lamb post-mortemed (of the 21).

13/6/85 - 10 lambs retested. The other 11 lambs had been sold for slaughter (since the last test) of the original 21 affected lambs. Titres ranged from 40 to negative (2 negative).

12/7/85 - The 10 lambs retested. Titres ranged from 20 to negative (5 negatives).

12/9/85 - The 10 lambs retested. Titres ranged from 20 to negative (1 lamb negative). A new lamb out of the original affected lambs was tested. It was the poorest of the lot and had an eye and nose discharge. Its titre was 20. It was not retested (it was low in condition 2 months prior to testing.

Blood tests on adults

17/6/85

19 of the ewes from the mob of 310 crossbreds which were the mothers of the affected lamb group were blood tested and 4 Dorset rams. Of the ewes - 1 was negative, 14 had titre of 10, 2 had titre of 20, 1 had titre of 10, 1 had titre of 160, and no clinical disease had been seen in the ewes.

Of the 4 rams tested - 1 was negative, and 3 had titre of 10.

History of ewes of affected lambs after 1 May, 1985

They were mated on 2 May 1985. They finished lambing by 6 November 1985. 340 lambs were marked and no signs of Chlamydiosis was seen in the lambs.

History of other ewes and lambs on the property

Approximately 170 crossbred ewes and 130 lambs were bought through the saleyards on 11 April 1985 (lambs 1 to 4 weeks of age). These sheep had over the fence contact with the affected mob and had no signs of disease. This mob of ewes and lambs was put in one of the flood irrigation paddocks approximately 3 weeks after the affected mob had gone.

Contact with cattle

No cattle are run on this property.

Serological investigations at Cowra agricultural research station

(Seaman, 1983)

Chlamydiosis was diagnosed in the Dorset ewe competition flock in October, 1982. All 160 ewes were bled on seven occasions from October, 1992, 10 September, 1983.

Overall, 86 of the 160 ewes developed some serological titre on at last one occasion when bled. Approximately 10% of sheep showed clinical signs of conjunctivitis and being tucked up but these were complicated by dusty conditions and drought.

The longest period that titres persisted for was nine months in one ewe but the average time seemed to be around three months. Some passing titres (10 or 20) were only seen at one bleed.

The final bleed on 5 September 1983 revealed only 19 ewes with serological titres (18 with 10 and one with a 20) none of which was considered positive. Those 19 ewes had all shown some titre on a previous bleed. On the last bleed, there were no ewes with new titres and all sheep were clinically healthy.

Seaman (1983b) regards Chlamydia Complement Fixation Test (CFT) titres of 40 or above as being positive and lower titres (10, 20) indicating passing exposure to the organism. Seaman also notes that Chlamydia are quite widespread in Australian sheep flocks and low titres of 10 or 20 are not uncommon in normal sheep.

Chlamydial disease concerning both sheep and cattle

(Littlejohns, 1976)

The common syndromes due to chlamydial infection, S.B.E. and polyarthritis of lambs, commonly occur at the same time and place. This naturally leads to suspicion that the same strain of chlamydia may be involved.

However, it was not the experience on the one property with sheep and cattle in this talk. The other two properties only had sheep.

Chlamydiosis in cattle in the Forbes Pastures Protection District

Property C

This property is 1700 acres (680 hectares) in area. It runs 30 cows plus progeny and a bull and 600 crossbred ewes. At the time of the visit, the cattle and sheep were being run separately. There was a cow mob and a separate steer and heifer mob consisting of 17 steers and heifers plus 2 cows. The steers and heifers were born on the property in July to September, 1984, were weaned at about 9 months and locked up on a 6 acre paddock with self-feeders (sodium bentonite, salt, lime, oats and cereal hay) when the weather was dry and then allowed out on a green pick of 3 paddocks just prior to the first visit on 2 July, 1985, but they still had access to the self-feeders right through to sale.

The stock were watered from dams filled by natural run-off.

A visit was made to the property on 2 July 1985 where an 11 months old Hereford cross steer was seen in lateral recumbency and was showing a slight dribbling of urine. Three days previous it was showing weakness in the hind legs and on the following day it went down. It was from a mob of 17 steers and heifers and 2 cows. They were being fed on oats and hay.

At post-mortem, there was darkening of the muscles of the hind leg close to the pelvis particularly on one side. The urinary bladder was very distended and blockage by urinary calculi was found. A considerable amount of straw coloured fluid was present in the joint capsules.

Laboratory results showed no visible organisms on smears of muscle and culture of the mesenteric lymph node joint fluid, and liver and kidney were negative. No Chlamydia was cultures from the joint fluid.

CFT for Chlamydia on the blood was 40.

On 30 August, 1985, a second visit was made to the property with a second steer showing signs of sickness. Its temperature was 39.6°C. It was humped up in the back and dopey. The whole herd was tested for Chlamydiosis and the steer gave a titre of 40. Five other animals showed titres, but were not observed to be sick. Titres of 160 (another steer), and a cow of 40, and three other animals of 10. An odd animal was hanging back in the mob. Terramycin L.A. was advised for the sick steer.

On 5 September 1985, a third visit was made to the property. One heifer was down in lateral recumbency, temperature 41°C. It was showing nasal and ocular discharge. Four other animals showed high temperatures 40.3°C to 40.7°C. They showed stiffness when walking. The five sick animals were bled and given Terramycin L.A. injections (1ml per 10 kg body weight). The heifer down had a titre of 40 CFT to Chlamydia and the others showed 3 x 10s and one negative. The heifer down was shot 2 to 3 days after the visit.

On 30 September 1985, a fourth visit was made. The cattle were continuing to have trouble with Chlamydiosis. Three more animals were injected with Terramycin L.A. that morning. They had temperatures of 40.5°c. A total of 10 of the animals had been injected. 17 animals were blood tested. Chlamydial titres ranged up to 640 (640, 2 x 320, 160, 80, 2 x 40, 2 x 20, 3 x 10, 5 negative).

The owner took temperatures and any with raised temperatures and showing clinical signs were injected. On 6 December 1985, a fifth visit was made and 11 animals were blood tested. Six animals had been sold on 14 October, 1985. The animals recovered except for one animal (a heifer, tag 52) which was still slightly depressed. Titres ranged up to 160 (160, 4 x 80, 2 x 40, 20, 10, 2 negative). (Tag 52 was dull, stiff and had a temperature of 40.5°C on 8 October 1985 when it was given its first injection).

	= = = = = = = DATE TESTED = = = = = = = =
	18 tested	5 tested	17 tested	11 tested
EAR TAG NO.	30/8/85	5/9/85	30/9/85	6/12/85
349141	160		320	sold
142	-ve		-ve	40
143	-ve	10	320	sold
144	-ve	10	40	sold
145	10		10	sold
146	-ve		10	80
147	-ve		-ve	-ve
148	-ve	-ve	10	sold
149	-ve	40	dead	dead
150	-ve	10	160	160
151	-ve		20	80
152	-ve		-ve	10
153	-ve		80	80
154 (cow)	10		-ve	-ve
155	-ve		-ve	sold
156	10		40	80
06726 (cow)	40		20	20
349182 (sick steer)	40		640	40

6 sold for slaughter on 14 October 1985.

Animals injected with only oxytetracycline.

CODE NO.	EAR TAG NO.	DATE INJECTED
1	349141
2	142	30/9/85
3	143	Sick - 5/9/85. Injected soon after. Temp. 40.7°C.
4	144	Sick - 5/9/85. Temp. 40.6 °C. Injected soon after.
5	145
6	146	30/9/85 (Temp. 40.5°C)
7	147
8	148	Sick - 5/9/85. Temp. 40.3°C. Injected soon after.
9	149	Sick and down 5/9/85. Temp. 41°C. Died.
10	150	Sick - 5/9/85. Temp. 40.5°C. Injected soon after.
11	151	30/9/85. Temp. 40.5°C.
12	152	6/12/85 and 8/10/85
13	153	Injected between 5/9 and 30/9/85 when temp. 40.7°C.
14	154
15	155	Injected before (5/9 & 30/9/85) although temp. only 39°C.
16	156
17 (cow)	06726
18 (steer)	No tag	Sick 30/8/85, temp. 39.6°C. Injected soon after.

12 of the 18 animals were injected - 10 of those showing temperatures. One of those animals died (shot) - treated late. The 18 animals included the 2 cows not injected.

Contact of cattle and lambs on Property C

The lambs are weaned at the earliest at 12 weeks of age, and put on a 200 acre paddock for fattening. The steer and heifer mob (plus the 2 cows) were put in with the lambs on the lucerne paddock in August, 1985, and were there till all the steers and heifers were sold on 13 January 1986. The lambs are kept on the lucerne paddock until sold. There was no problem of Chlamydiosis in the lambs. There were approximately 200 lambs on the lucerne at the same time as the cattle (crossbred lambs).

Test on cows - mothers of affected mob, on Property C (5/3/86)

(8 months from date of first post-mortem on the property)

Number of cows tested - 30 (another cow not tested due to being heavy in calf), plus 1 bull (Simmental - 3 years old, introduced 1984)

Chlamydial titres.

1 cow titre 160

1 cow titre 20 (previously tested 6/12/85 CFT 20 )

3 cows titre 10

1 bull titre 80

Remaining cows (25) negative titres.

All animals were healthy.

Cows are Illawarra - born on the property.

Isolation of Chlamydia psittaci from an aborted bovine foetus in the Forbes district

Seaman, Scrivener, and Cockram (1986) reported the isolation of Chlamydia psittaci from an aborted bovine foetus in a herd with a previous history of S.B.E. in the Forbes district (A.V.J. - to be published).

The abortion occurred in a group of 20 three year old cows which had been introduced when pregnant onto the farm. Another five cows in the group were found with dead full term calves in the paddock. This group was running with other cattle which had experienced a clinical episode of S.B.E. approximately 4 to 6 weeks previously.

ConclusionS

(1) Positive cultures

Positive chlamydial cultures were found in the following.

Property A -

1. 2 live lambs submitted to the Regional Veterinary Laboratory on 2 June, 1982.

(a) positive culture on pooled tissues post-mortemed on 24 June, 1982.

(b) lamb 2 - positive chlamydial culture from blood collected 24 June 1982, but none after that for testing up to 12 July 1982.

2. 2 lambs submitted to Regional Veterinary Laboratory on 16 November, 1982.

(a) one positive from eyes 9 days after submission

(b) both positive from eyes 13 days after submission

(c) one post-mortemed 7 months after submission, negative on pooled tissues.

3. From 9 lambs submitted on 18 January 1983 and post-mortemed -

2 lambs positive culture, all tissues

2 lambs positive culture, eye swabs.

(2) Chlamydial titres

Persistence of Chlamydial titres in animals was found as follows:-

Of two lambs tested at the Regional Veterinary Laboratory, from property A -

* 1 lamb went negative after 50 days (from an initial titre of 80)

* the other lamb was still showing litre of 10 after 99 days, although showed a negative titre after 63 days of testing.

Property B.

Titres of 10 and 20s were still showing after 4 months of testing in 10 out of 11 lambs tested.

Property C

High titres were still showing up in the herd 5 months after testing the first animal.(cattle)

Dorset ewe competition flock - Cowra Agricultural Research Station (J Seaman, pers. com)

Total number of ewes with titres 86/160,i.e. 53.7%.

Longest period of a titre in one ewe was 9 months.

Average time of titre in animals was approximately 3 months.

(1) Property A

Chlamydiosis was investigated on Property A close to Forbes, which experienced the disease from March 1982, to December, 1984, in crossbred lambs aged 2 weeks to 4 months. It was only seen on two lucerne paddocks on the property which had a high water table. The disease followed a stress such as weaning or cold and wet weather. The owner routinely mixed his ewe mobs together in the course of his management.

(2) Property B

Chlamydiosis was investigated in a mob of 350 crossbred lambs, February 1985 drop, on property B, on an irrigation property close to Forbes. The owner first noticed clinical signs of the disease in March, 1985. The lambs were first seen by the writer on 1 May 1985. The owner undertook a Terramycin L.A. treatment programme of the sick lambs and no more new cases of disease was seen after 17 May 1986, except for one lamb, poor in condition and with an ocular and nasal discharge seen on 12 September, 1985. All lambs were sold by the end of the year.

(3) Property C

Sporadic Bovine Encephalomyelitis was diagnosed in a small group of 18 cattle in the Forbes Pastures Protection District. An 11 months old steer was post-mortemed on 2 July 1985 and four lots of blood tests were done on the cattle from 30 August 1985 to 5 December 1985. A total of two animals died on the property (steer and a heifer). Sickness continued in new animals on the visit on 30 September 1985, but animals were healthy at the visit on 6 December 1985, except for one animal. Sick animals were injected with Oxytetracycline L.A., animals showing raised temperatures and clinical signs being treated. The animal injected on 6 December, 1985, came good a few days after, but remained poorer in condition compared with the other cattle. The remaining steers and heifers were sold in mid January 1986 (13 January, 1986). The mothers of the affected mob and a bull were tested on 5 March, 1986.

Acknowledgements

Grateful acknowledgements are made to:

1. Mr John Seaman of the Regional Veterinary Laboratory, Orange for the work done on lambs and specimens submitted to the Regional Veterinary Laboratory, and also his assistance with information on his trial at Cowra Agricultural Research Station.
2. The owners of the three properties who experienced Chlamydiosis in their animals for their assistance in the investigations.
3. The Regional Veterinary Laboratory, Orange, staff for testing samples.
4. Mrs Jayne Norrie for the typing.

References

1. Graham, DM (1976) - Proceedings No. 27. Infectious Diseases in the Twilight Zone - Post-grad. Com. in Vet. Science, p 254 - 268.
2. Jackson, AR (1965) - Veterinary Notes, NSW Dept. of Agriculture, Vol. 1, No. 1, p 3.
3. Littlejohns, I (1976) - Proceedings No. 27. Post-grad. Con in Vet Science, p 193 - 197.
4. Seaman, JT (1982) - N.S.W. Dept. of Ag. Conference Proceedings (1982) p 92. - for Veterinary Officers
5. Seaman, JT (1983a) - Progress Report to 28/2/83 - Chlamydial Diseases of Sheep - Regional Veterinary Lab. Orange - Agricultural Research & Vet. Cntre.
6. Seaman, JT (1983b) pers. com.
7. Seaman, JT; Scrivener, CJ; and Cockram, FA (1986) - Australian Veterinary Journal - to be published.
8. Seaman, JT (1985) - Aust. Vet. J. 62: 436
9. Shewen, PE (1980) - Canadian Vet. J. 21 : 2-11.
10. Webb, R (1981) - Inaugural Interlab. Monthly Report, Regional Veterinary Laboratory, Orange (October)

Other Useful Reference

Henridge, WIB - Animal Health in Australia - Vol. 1. Viral Diseases of Farm Livestock. P 76-82.