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A SCIENTIFIC REVIEW OF LEPTOSPIROSIS AND IMPLICATIONS FOR

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A SCIENTIFIC REVIEW OF LEPTOSPIROSIS AND IMPLICATIONS FORA,of,a,and,for

BIOSECURITY

    AUSTRALIA

    A SCIENTIFIC REVIEW OF LEPTOSPIROSIS

    AND IMPLICATIONS FOR QUARANTINE

    POLICY

    Biosecurity Australia

    Agriculture, Fisheries and Forestry - Australia

    ox 858 GPO B

    Canberra ACT 2601

    AUSTRALIA

ACKNOWLEDGEMENTS

    The review of Australia‟s quarantine policy for leptospirosis was prepared by Dr George Perry. Dr Robert Heard assisted with information on antibiotics and vaccination. Drs Geoff Ryan, Greg Oliver, Bernard Robinson, Judith Bourne and Robyn Martin provided editorial input. All are officers of Animal Biosecurity, Biosecurity Australia, AFFA.

    Biosecurity Australia thanks the following for assisting with editing parts of the draft document and for their support and advice:

    Emeritus Professor Solomon Faine of MediSci Consulting, Armadale, Victoria; and Dr Lee Smythe, Supervising Scientist, WHO/FAO Collaborating Centre for Reference and Research on Leptospirosis, Brisbane, Queensland.

    The electron micrograph picture of the Leptospira on the front cover of the review was copied from the International Leptospirosis Society (ILS) Website by kind permission of Dr Lee Smythe, President of the ILS and was provided by Monash University by courtesy of Prof. S Faine.

COPYRIGHT NOTICE

    Copyright ? 2000 Commonwealth of Australia.

    This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be

    reproduced by any process without prior written permission from the Commonwealth. Requests and inquiries concerning reproduction and rights should be addressed to the General Manager, Animal

    Biosecurity, Biosecurity Australia, GPO Box 858, Canberra ACT 2601.

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    TABLE OF CONTENTS

    ACKNOWLEDGEMENTS ..................................................................................................... ii

    EXECUTIVE SUMMARY ...................................................................................................... 1

1. Introduction ..................................................................................................................... 4

     National obligations ........................................................................................................ 6 2.

    a) Commonwealth ....................................................................................................... 6

    b) State / Territory ........................................................................................................ 6

    3. International Obligations ............................................................................................... 7

4. Australia’s surveillance and monitoring systems for Leptospira. ............................... 8

    a) Australia‟s disease status ......................................................................................... 8

    b) Australia‟s diagnostic capabilities ........................................................................... 8

    c) Domestic surveillance for human leptospirosis ....................................................... 9

    5. Current export and import requirements for leptospirosis ...................................... 10

    a) Export requirements for leptospirosis ................................................................... 10

    b) Current import requirements for leptospirosis ...................................................... 11

    6. Leptospirosis in Australia ............................................................................................ 13

    a) Humans .................................................................................................................. 13

    b) Animals ................................................................................................................. 13

    i. Cattle ............................................................................................................ 13

    ii. Sheep ............................................................................................................ 14

    iii. Pigs ............................................................................................................... 14

    iv. Feral Pigs ..................................................................................................... 15

    v. Dogs ............................................................................................................. 15

    vi. Cats .............................................................................................................. 16

    vii. Horses .......................................................................................................... 16

    viii Other mammals ............................................................................................ 17

7. International .................................................................................................................. 18

    a) New Zealand .......................................................................................................... 18

    i. Cattle ............................................................................................................ 18

    ii. Sheep and goats ............................................................................................ 19

    iii. Pigs ............................................................................................................... 19

    iv. Dogs ............................................................................................................. 19

    v. Horses .......................................................................................................... 20

    vi. Deer .............................................................................................................. 20

    vii. Possums ....................................................................................................... 20

    b) Europe ................................................................................................................... 21

    i. Cattle ............................................................................................................ 21

    ii. Pigs ............................................................................................................... 21

    iii. Horses .......................................................................................................... 22

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    iv. Dogs ............................................................................................................. 22

    v. Sheep ............................................................................................................ 22

    vi. Other mammals ............................................................................................ 23

    vii. Small mammals ............................................................................................ 23 c) Africa ..................................................................................................................... 24

    i. Cattle ............................................................................................................ 24

    ii. Pigs ............................................................................................................... 24

    iii. Dogs ............................................................................................................. 25

    iv. Horses .......................................................................................................... 25

    v. Other mammals ............................................................................................ 25 d) Asia ........................................................................................................................ 25

    i. Cattle ............................................................................................................ 26

    ii. Pigs ............................................................................................................... 26

    iii. Horses .......................................................................................................... 27

    iv. Small mammals ............................................................................................ 27

    v. Other mammals ............................................................................................ 27 e) North America ....................................................................................................... 27

    i. Cattle ............................................................................................................ 27

    ii. Pigs ............................................................................................................... 28

    iii. Horses .......................................................................................................... 28

    iv. Dogs ............................................................................................................. 29

    v. Small mammals ............................................................................................ 29

    vi. Other mammals and reptiles ........................................................................ 29 f) South America ....................................................................................................... 29

    i. Cattle ............................................................................................................ 29

    ii. Pigs ............................................................................................................... 30

    iii. Horses .......................................................................................................... 30

    iv. Dogs ............................................................................................................. 31

    v. Small mammals and reptiles ........................................................................ 31

    vi. Camelids ...................................................................................................... 31 g) Experimental infection in animals ......................................................................... 32 h. Infection in pinnipeds ............................................................................................ 32

    8. Leptospires .................................................................................................................... 34

    a) Serogroup australis ................................................................................................ 35

    i. L interrogans sv australis ............................................................................. 36

    ii. L interrogans sv bratislava........................................................................... 36 b) Serogroup ballum .................................................................................................. 36

    i. L borgpetersenii sv ballum .......................................................................... 36 c) Serogroup canicola ................................................................................................ 36

    i. L interrogans sv canicola ............................................................................. 36 d) Serogroup celledoni ............................................................................................... 36

    i. L weilii sv celledoni ..................................................................................... 36 e) Serogroup grippotyphosa ....................................................................................... 36

    i. L interrogans sv grippotyphosa ................................................................... 36

    f) Serogroup icterohaemorrhagiae ............................................................................. 37

    i. L interrogans sv copenhageni ...................................................................... 37

    ii. L interrogans sv icterohaemorrhagiae ......................................................... 37

    g) Serogroup pomona ................................................................................................ 37

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    i. L interrogans sv pomona ............................................................................. 37 h) Serogroup pyrogenes ............................................................................................. 38

    i. L interrogans sv zanoni ............................................................................... 38 i) Serogroup sejroe .................................................................................................... 38

    i. L borgpetersenii sv balcanica ...................................................................... 38

    ii. L borgpetersenii sv hardjo ........................................................................... 38

    iii. L interrogans sv hardjo ................................................................................ 39

    iv. L interrogans sv medanensis ....................................................................... 39

    v. L borgpetersenii sv sejroe ............................................................................ 39

    vi. L interrogans sv wolffi ................................................................................ 39 j) Serogroup tarassovi ............................................................................................... 39

    i. L borgpetersenii sv tarassovi ....................................................................... 39

    9. Epidemiology ................................................................................................................. 40

    a) Factors affecting transmission ............................................................................... 40 b) Factors affecting prevalence of leptospirosis ........................................................ 42 c) Factors affecting severity of leptospirosis in an animal ........................................ 42 d) Distribution of Leptospira species and serovars .................................................... 43

    i. Geographical distribution ............................................................................. 43

    ii. Host distribution .......................................................................................... 43

    iii. Distribution of rodents ................................................................................. 43

    10. Risk of introduction, establishment, spread and consequence ................................. 45 a) Likelihood of entry ................................................................................................ 45

    i. Animals ........................................................................................................ 45

    ii. Semen and embryos ..................................................................................... 46

    iii. Animal derived tissue cultures ..................................................................... 46

    iv. Contaminated material ................................................................................. 46 b) Likelihood of exposure .......................................................................................... 46 c) Likelihood of undesirable consequence ................................................................ 47

    i. Establishment ............................................................................................... 47

    ii. Spread .......................................................................................................... 47

    iii. Biological consequence of agent introduction and disease establishment in

    Australia ....................................................................................................... 48

    iv. Environmental consequence of agent introduction and disease establishment

    in Australia ................................................................................................... 49

    v. Economic consequence of agent introduction and disease establishment in

    Australia ....................................................................................................... 49 d) Overall risk ............................................................................................................ 50

    i. Introduction .................................................................................................. 50 e) Risk event models ................................................................................................. 52

    i. Possible entry and exposure events .............................................................. 52

    ii. Possible consequence events ........................................................................ 54

    iii. Importing dogs with sv canicola infection. .................................................. 56

    iv. Importing pigs or sheep with sv canicola infection. .................................... 57

    v. Importing dogs infected with serovars not reported in Australian animals

    (apart from sv canicola infection.) ............................................................... 58

    vi. Importing cattle with sv hardjoprajitno infection ........................................ 59

    vii. Importing livestock with sv kennewicki or mozdok infection ..................... 60

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    viii. Importing horses with leptospiral infection ................................................. 61

    ix. Live pigs infected with sg australis from Europe ......................................... 62

    x. Rodents and other small mammals .............................................................. 63

    xi. Animals or humans infected with sv lai ....................................................... 64

    xii. Semen, embryos and tissue culture cells. ..................................................... 65

    xiii. Summary of overall risk ............................................................................... 66

11. Risk evaluation .............................................................................................................. 67

     Risk reduction ............................................................................................................... 68 12.

    a) Introduction ........................................................................................................... 68

    b) Risk reduction strategies ....................................................................................... 68

    i. Serology ....................................................................................................... 69

    ii. Isolation and culture ..................................................................................... 69

    iii. Detection of leptospiral DNA ...................................................................... 70

    iv. Antibiotics .................................................................................................... 70

    v. Disinfection of premises and hygiene .......................................................... 72

    vi. Disease history ............................................................................................. 72

    vii. Vaccination .................................................................................................. 73

    viii. Rodent control and biosecurity measures to ensure isolation from carriers 73

    ix. Surveillance .................................................................................................. 73

    x. Hygiene ........................................................................................................ 74

    13. Implications for quarantine policy .............................................................................. 75

    a) Human quarantine policy ...................................................................................... 75

    b) Animal quarantine policy ...................................................................................... 75

    i. Semen and embryos ..................................................................................... 75

    ii. Animal derived tissue cultures ..................................................................... 76

    iii. Pet rodents and other small mammals ......................................................... 76

    c) Public health risks during quarantine and transport .............................................. 76

    d) Possible effects of stricter notification requirements for leptospirosis ................. 76

    14. Proposed options for export conditions ...................................................................... 78

15. OIE International Animal Health Code Leptospirosis Chapter. ............................. 80

Appendix 1 Table of Leptospira serovars sorted by serogroup and genomospecies. 83

References ............................................................................................................................... 86

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EXECUTIVE SUMMARY

    Leptospirosis is a contagious disease of animals and humans caused by the spirochaete Leptospira of which there are two forms, the pathogenic species and the non-pathogenic *(benign) species. Only the pathogenic Leptospira species are considered in this review.

    In Australia, clinical leptospirosis occurs in cattle (serovars (svs) hardjo, pomona and zanoni) and pigs (pomona, tarassovi and bratislava). Sporadic cases occur in sheep (hardjo), horses (pomona) and dogs (copenhageni and australis). Clinical cases have been reported in humans with svs australis and zanoni predominating in the tropics, and sv hardjo predominating, with some sv pomona and occasionally sv tarassovi, in the temperate regions of Australia.

    In other countries, many animal species may be infected with leptospira serovars considered exotic to Australia. Some serovars are highly pathogenic to animals or humans or both. Many exotic serovars are carried by maintenance hosts not found in Australia and consequently may not establish in Australia, despite the perceived possibility of exotic serovars adapting to new hosts and establishing in this country.

    Australian quarantine restrictions for leptospirosis are currently confined to the requirement that dogs give a negative result to an antibody test for L interrogans sv canicola despite this

    serovar having been isolated from a human in Australia. In contrast, many of Australia‟s trading partners impose import conditions for leptospirosis in most livestock species, horses, dogs, cats, and their genetic material.

    Because pathogenic leptospires interact with the host and the environment in complex ways, this review discussed a number of leptospira serovars individually. AQIS evaluated the risk associated with several different serovars, host species (including humans) and circumstances.

    Leptospirosis is not a notifiable disease of animals in some Australian States and Territories and there is evidence of lack of regulatory action where leptospirosis has been notified. This has impacted on the consequence of entry, establishment and spread of leptospirosis, which is evaluated as „negligible‟ to „low‟ except where a risk event suggests there could be serious public health risks.

    The qualitative method used to derive these risks is described in the review. The results of this evaluation are summarised in Table A.

Australia‟s acceptable level of protection is the level of protection deemed acceptable by

    Australian public health and veterinary authorities in managing the disease within their territories. Australia has limited requirements for the control of leptospirosis within its territory. Clinical disease in animals and humans generally occurs sporadically, and prevention and control of leptospirosis is not mandatory. Thus where the overall risk is assessed to be negligible or low, the imported animal or animal product satisfies Australia‟s acceptable level of protection without requiring quarantine measures to further manage the risk of leptospirosis.

     * Standard nomenclature requires that the species be written in italics, for example, Leptospira

    interrogans or L. interrogans but serovars and serogroups be written in standard text.

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    But where the overall risk is considered to be moderate or high, that is, for:

    ; semen and embryos,

    ; animal derived tissue cultures, and

    ; pet rodents and other small mammals, a quarantine measure was considered for each of the risk events.

Table A.

    Scenario Risk Importing a dog from a country with a significant stray dog problem, where Low canicola infection occurs and dogs are not routinely vaccinated (eg, most African,

    Asian or South American countries).

    Importing a dog from a country where sv canicola has not been isolated from Low dogs since the 1950‟s (eg, USA, Canada, and New Zealand).

    Importing a pig clinically infected with sv canicola (eg, Republic of South Negligible Africa).

    Importing a ram infected with sv canicola (eg, Portugal). Low Importing a dog from a country which reports dogs with antibody titres to svs Low batavia, bratislava, javanica and cynopteri, none of which has been reported in

    Australia (eg, Southeast Asia).

    Importing a dog from country where infections due to sv bim occurs (eg, the Low Carribean).

    Importing a bull infected with sv hardjoprajitno from a country where this serovar Low is endemic (eg, Ireland).

    Importing a pregnant cow with sv hardjoprajitno infection from a country where Low this serovar is endemic (eg, Ireland).

    Importing a cow shedding either of svs mozdok or kennewicki in urine (eg Low Europe or North America).

    Importing a boar shedding either of svs mozdok or kennewicki in urine (eg Low Europe or North America).

    Importing a non-pregnant racehorse for a temporary stay of 2 months for Low competition purposes (eg, North America).

    Importing a pregnant mare with foetus infected with a serovar exotic to Australia Low (eg, Europe - sv mozdok and North America sv kennewicki).

    Importing a boar with sg australis infection (eg, Europe). Low An infected carrier rat escapes from a ship and enters Australia. Low Importing an infected pet rat (eg, Asia). Moderate Animal or humans infected with sv lai enter Australia (eg, Asia). Negligible Untreated frozen semen from untested donors infected with exotic pathogenic Negligible leptospires (eg, Europe, South America)

    Importing a batch of animal vaccine containing cell lines prepared from infected Moderate animal kidneys (eg, Asia).

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    As effective antibiotics are routinely used in the processing of semen, embryos and animal derived tissue cultures, there is no need to impose additional quarantine conditions. For pet rodents and other small mammals, the proposed quarantine requirement is that these mammals must come from colonies tested free from leptospiral strains that are „exotic‟ to Australia and

    relevant to the species.

    Several of Australia‟s trading partners impose quarantine conditions for leptospirosis. Some require animals to be injected with streptomycin/dihydrostreptomycin (S/DHS) prior to export. While S/DHS is usually the most effective antibiotic for treatment of leptospirosis, it does not always sterilise infection and thus it is not an effective quarantine measure. Several countries, including Australia, no longer use S/DHS in food-producing animals as the injection causes local irritation and pain and treatment can cause residue problems in food products. In Australia, it can only be used by permit from the National Registration Authority (NRA) in food-producing animals. Because of the small demand for this antibiotic, pharmaceutical companies are not restocking their supplies and it has becoming increasingly difficult to obtain S/DHS for use in export livestock. Australia will either need to renegotiate those import conditions that require S/DHS treatment for leptospirosis or make arrangements for the importation of S/SDH specifically for use in export livestock. However, the latter option does not address the problem of managing stock treated with S/SDH then withheld from export.

Other quarantine measures for leptospirosis, including those recommended in the OIE Code,

    are also of questionable value. Australia intends to draw this to the attention of other countries and propose revised guidelines for leptospirosis in the OIE Code.

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1. Introduction

    Leptospirosis is a contagious disease of animals and humans caused by the spirochaete Leptospira of which there are two groups, the pathogenic species and the non-pathogenic (benign) species. Only the pathogenic Leptospira species are considered in this review. Over

    the years, the classification of the genus Leptospira has undergone some changes and is now

    currently classified in two ways:

    1. on the basis of agglutinating antigens into over 250 serovars contained within 23

    serogroups;

    2. on the basis of DNA studies with all 250 plus serovars placed into eight genomospecies. There are proposals for further changes to the classification system but this will not be considered in this report. There is still considerable confusion on the current taxonomy of the leptospires, largely because serovars were previously grouped into one of 2 species, interrogans and biflexa and are now grouped into a number of species. Appendix 1 lists the known pathogenic Leptospira serovars according to genomospecies and serogroups.

    The bacteria can cause polymorphic disease conditions in domestic animals, wildlife and humans. Infections range from asymptomatic or subclinical to acute and fatal. Symptoms of acute leptospirosis in animals include sudden agalactia in the lactating female, icterus and haemoglobinuria in the young, nephritis and hepatitis in dogs, and meningitis. Chronic leptospirosis can cause abortion, stillbirth, runting, and infertility. Often chronically infected animals remain as asymptomatic carriers for life with the organism localised in the kidneys and in the reproductive organs. Horses can develop periodic ophthalmia as a result of leptospirosis.

    In humans, leptospirosis can cause headaches, fever, chills, sweats and myalgia. Other symptoms may include lethargy, aching joints, and long periods of sickness. Some highly pathogenic serovars may cause pulmonary haemorrhaging and death. While mild type leptospirosis is probably the most common form of infection, they can sometimes be chronic in nature and have a „mental‟ component to their clinical manifestations.

    In Australia, clinical leptospirosis is most common in cattle (svs hardjo and pomona) and pigs (pomona). A number of other serovars have also caused disease in these two species. Sporadic cases occur in sheep (hardjo), horses (tarassovi) and dogs (copenhageni). There are no reports of clinical leptospirosis in camels although leptospira antibodies have been detected in camels. Clinical cases have been reported in humans with svs australis and zanoni predominating in the tropics, and svs hardjo predominating, with some sv pomona and occasionally sv tarassovi, in the temperate regions of Australia.

    Leptospirosis is of increasing importance as an occupational disease as intensive farming practices become more widely adopted. During 1999, those working in agricultural industries in Australia accounted for 35.3% of notifications while those working in livestock industries 1accounted for 22.9% of notifications.

    Australian quarantine restrictions for leptospirosis are currently confined to the requirement that dogs give a negative result to an antibody test for L interrogans sv canicola. This serovar

    is considered exotic to Australia despite having been isolated from a human in Australia. In contrast, several of Australia‟s trading partners impose import conditions for several leptospira serogroups in livestock species, horses, dogs, cats, and their genetic material.

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