ANIMALS Exotic pest and disease focus for companion vets

This article describes a number of exotic as the Terrestrial Animal Health Code help rule out any suspected exotic, new pests or diseases affecting dogs or cats (World Organisation for Animal Health, or emerging diseases. that may be encountered in imported 2013). However, WTO members can companion . It also describes the choose to adopt measures that result in Exotic disease case notes for measures in place to ensure biosecurity a higher level of protection than that veterinarians in practice threats are managed effectively. provided by international standards, Following are details of imported pests provided these are supported by an IRA. The Ministry for Primary Industries and diseases that may present in first- (MPI) ensures New Zealand’s plants, MPI’s IRA for cats, dogs, and canine opinion companion animal veterinary animals and natural resources remain semen was published in November 2009 practice. Cases of three of these diseases free from harmful pests and diseases. and provides the scientific basis for the (all of which are notifiable under the Our biosecurity system includes: measures currently applied to imported Biosecurity Act 1993) have recently been • pre-border measures (import health companion animals. This document is diagnosed in New Zealand: ehrlichiosis, standards – IHSs) that detail the publicly available at www.mpi.govt.nz/ leishmaniasis, and brown dog ticks. testing and inspection of animals document-vault/2796. Attending veterinarians and pathologists required before importing them; worked closely in partnership with MPI • border measures, including Post-border controls to investigate and manage these cases. inspection and quarantine, carried New Zealand’s exotic pest and disease control measures are among the best Ehrlichia canis – Canine monocytic out on arrival or soon after arrival at ehrlichiosis registered Transitional Facilities; and in the world, although no system can eliminate all risk. Maintaining our Worldwide situation: E. canis is • post-border surveillance to inform animal health status also requires reliable widespread in tropical and semi-tropical investigation and response to systems to investigate and respond to regions. This intracellular bacterium biosecurity threats. suspect incursions of exotic disease. is transmitted by the brown dog tick, Practising veterinarians seeing and Rhipicephalus sanguineus. There are Pre-border and border reporting unusual signs and events no reports of natural transmission by controls underpin New Zealand’s animal disease any other means. Import risk analysis (IRA) is a surveillance system (Tana, 2014). New Zealand context: E. canis testing is scientific discipline that transparently MPI’s Investigation and Diagnostic not a requirement of New Zealand’s IHS accommodates known facts, knowledge Centre (IDC) at Wallaceville manages for dogs because the vector is not present gaps and uncertainty (Vose, 2008; World the investigation of, and initial response here. The endemic tick Haemaphysalis Organisation for Animal Health, 2010). to, any suspected exotic animal disease longicornis may feed on dogs, but is not MPI uses IRA to identify pre-border or pest, as well as new or emerging an Ehrlichia vector. At present, owing to hazards such as pathogens that may be syndromes. Animal Incursion the lack of any vector, E. canis is unlikely associated with imported animals, and to Investigators are veterinarians with to become established in New Zealand, assess the likelihood and consequences postgraduate training in epidemiology so it is important to ensure that ticks that of introducing those hazards. IRA and/or pathology, and relevant further could be vectors are not introduced on also informs control measures to training in exotic diseases and pests. They imported cats and dogs (MPI, 2009). manage the identified risks, and helps are supported by expert bacteriologists, communicate the risks to others (Cobb & Clinical presentation: Acute infection virologists, immunologists and MacDiarmid, 2014). is characterised by fever, generalised parasitologists at MPI’s Animal Health lymphadenopathy, splenomegaly and As a signatory to the World Trade Laboratory (AHL) and Plant Health and thrombocytopenia. New Zealand Organisation (WTO) Agreement Environment Laboratory (PHEL). veterinarians are unlikely to see acute on the Application of Sanitary and Veterinary Incursion Investigators cases because sick animals should Phytosanitary Measures, New Zealand respond to calls to the MPI pest and not have been cleared to leave their can employ control measures to imported disease hotline (0800 809 966), typically country of origin. Some dogs that animals, but these measures must from farmers, veterinarians or veterinary recover from the acute phase can remain not be applied arbitrarily, or result in pathologists. MPI investigators are subclinically infected for months or discrimination between countries where willing to hear and discuss any cases years, during which they may clear the similar conditions prevail, or constitute and concerns, however insignificant organism, remain infected or develop a disguised restriction on trade (World they may seem at first, to maximise the chronic disease. It is therefore more Trade Organisation, 1995). WTO likelihood of detecting exotic diseases. likely that chronic-stage infection members agree to base their control They are not concerned if cases under could be presented to a veterinarian measures on international standards, discussion turn out to be false alarms, in New Zealand. Chronic infection is guidelines and recommendations, such and are happy to provide consultancy to characterised by progressive weight loss,

4 Surveillance 43 (2) 2016 bleeding disorders and renal failure. Diseased dogs also have impaired to identify the organism to level. Clinical findings may also include immunity. This is thought to be caused Treatment options: Leishmaniasis can anaemia, splenomegaly, interstitial by the parasite, as decreased cellular be treated but is not considered curable. pneumonitis, ocular lesions (e.g., anterior immunity coincides with escape Treatment with meglumine antimoniate uveitis, hyphema – see Figure 1) and and replication of Leishmania from and allopurinol is the preferred option meningitis (McQuiston, 2014). macrophages. Sick dogs are likely to have for most stages of the disease, but high levels of parasitaemia and spread Laboratory findings and confirmation: meglumine antimoniate is not available the protozoan back to the sandfly vector. Routine bloodwork in chronic- for veterinary use in New Zealand and Dogs with healthy immune systems stage E. canis infection will typically importation requires ACVM approval. will experience a lag of weeks to years identify a non-regenerative anaemia, Successful treatment results in decreased between exposure and development of thrombocytopenia, lymphocytosis parasitaemia, but treated dogs are still disease (Solano-Gallego et al., 2009). and neutrophilia. Serum considered carriers (Solano-Gallego During this time individuals will often biochemistry changes often include et al., 2009). be seronegative, because the parasite is azotaemia, hyperglobulinaemia and adapted to hide within macrophages. hypoalbuminaemia (McQuiston, 2014). Exotic ticks Conversely, clinically ill dogs usually have Parasites seen within lymphocytes in Worldwide situation: Recent estimates high antibody titres. acute-stage infection are rare in chronic are that 390 of the 900 species of tick stage ehrlichiosis. Ehrlichia infection Laboratory findings and confirmation: across the world can infest people and can be confirmed by PCR testing; IFAT IFAT testing at the MPI AHL may their companion animals (Heath and testing is unhelpful on its own as titres confirm a diagnosis in the face of Hardwick, 2011). Many carry a variety of in dogs that have cleared infection may a suitable travel history, suspicious blood-borne pathogens. Their ability to remain high for many years. clinical signs, or presence of suspicious vector exotic diseases is the reason that organisms on cytology. PCR on blood all exotic tick species are notifiable under Treatment options: Doxycycline therapy and lymph-node aspirates is performed the Biosecurity Act 1993. at 10 mg/kg for 28 days is sufficient to sterilise chronic infection (Neer et New Zealand context: al., 2002). There is a potential onward Only 11 species of transmission risk associated with tick are present in bone marrow transplants and blood New Zealand. Most transfusions, so chronically infected parasitise wild birds, animals should not be used as donors. but one, the cattle tick Haemaphysalis Leishmania infantum – Canine longicornis, is associated leishmaniasis with domestic animals. Worldwide situation: The protozoan Despite stringent parasite Leishmania infantum is found IHS measures against in more than 70 countries, including ticks, there have been southern Europe (especially Spain), increasing numbers of exotic tick interceptions Africa, Asia, South and Central America Figure 1: Anterior uveitis and bleeding disorders such as (where it is called L. chagasi) and epistaxis and hyphema are potential sequelae to chronic at the border in sporadically in the US. Ehrlichia canis infection. Photo: K Gelatt, www.merck.com recent years and at least 17 species have New Zealand context: Import been identified and requirements for dogs do not eradicated. Most of these include testing for L. infantum parasitic hitchhikers because New Zealand does not have originate from Australia, phlebotomine sandflies, which are the Pacific Islands, Asia the primary vectors of the disease and North America and necessary for completion of the (Heath and Hardwick, parasite’s life cycle. 2011). Most commonly Clinical presentation: Dogs may they are carried into present with skin lesions, generalised New Zealand on lymphadenomegaly, progressive people or dogs and weight loss, muscular atrophy, exercise they can also arrive intolerance, decreased appetite, lethargy, with imported goods splenomegaly, polyuria and polydypsia, (Loth, 2005). ocular lesions, epistaxis, onychogryphosis The two most commonly Figure 2: Lymph node aspirate showing macrophages containing (overgrowth and curling of the nails), intercepted exotic ticks lameness, vomiting and diarrhoea. characteristic intracellular Leishmania infantum amastigotes (arrows) with characteristic perpendicularly-orientated on dogs are the brown Cytology of enlarged lymph nodes kinetoplasts. Photo: Rebecca Cairns & Janice Thompson, dog tick (Rhipicephalus reveals the characteristic organisms Gribbles Veterinary Pathology. Scale bar: 20μ. sanguineus) and the (Figure 2). Surveillance 43 (2) 2016 5 paralysis tick (Ixodes holocyclus). Both commonly in dogs than cats, and more are present in Australia: R. sanguineus is than 70 species of can serve as common in the north and also found in intermediate hosts. the west and east, while I. holocyclus is New Zealand context: New Zealand confined to the eastern seaboard. is free of D. immitis but has Clinical presentation: In the veterinary three potential vector mosquito clinic these ticks may not be easy to spot. species ( notoscriptus, Culex Although engorged, adult female brown quinquefasciatus and Aedes australis), dog ticks can reach 12 mm in length, the so stringent IHS measures are in place larval and nymph stages can be as small against heartworm in dogs.

as 1 mm. Common areas of attachment 2mm In regions where there is a high are the dog’s ears, neck and shoulders, density of infested dogs, cats can also and larvae can also be found on the belly be infested with D. immitis. However, and flank. Cats are not the preferred host Figure 3: Dorsal view of a semi-engorged cats are aberrant, dead-end hosts for many tick species and are less likely Rhipicephalus sanguineus (brown dog tick), showing the visible eyes either side of the because microfilaraemia is uncommon to carry ticks. scutum that can distinguish this species from and the parasite rarely undergoes the New Zealand cattle tick. Photo: Qing Hai There is a possibility that a dog or cat Fan, MPI. final maturation in cats (McSporran, infested with I. holocyclus could present 1994). Therefore IHS measures are not with tick paralysis caused by the potent necessary for imported cats (MPI, 2009). neurotoxins in the tick’s saliva. Clinical Clinical presentation: Infested animals signs include a rapid ascending flaccid may be sub-clinical. Mild and often muscular paralysis that can manifest transitory respiratory signs can occur as a progressive deterioration in the 3–4 months post-infestation, when the ability to vocalise, coordinate the hind juvenile worms arrive in the lungs. Later, limbs, breathe or eat (Barker et al., when the animals harbour mature worms 2014). Affected cats may also become in the pulmonary vasculature, they extremely anxious. may exhibit signs such as intermittent Laboratory findings and confirmation: vomiting, lethargy, anorexia, coughing, Tick species are distinguished by their episodic dyspnoea, epistaxis, or syncope. morphological characteristics: see Ascites can be seen in some animals, Figures 3, 4 and 5. These are guides owing to right-sided congested heart only and confirmation of species failure. Two to five years after infestation requires microscopic examination. If the death of adult heartworms can lead to

you find a tick on an animal and you 2mm acute respiratory distress, which may be are not confident that it is a cattle tick, fatal (Guerrero 2012). please call the exotic disease and pest Laboratory findings and confirmation: hotline and discuss the case with one of Figure 4: Dorsal view of Ixodes holocyclus The suspicion of heartworm disease in our veterinarians. (Australian paralysis tick). Note the distinctive a dog or cat in New Zealand would be darker colouration of the first and fourth pairs of Treatment: Removal of brown dog ticks legs. Photo: Qing Hai Fan, MPI. based initially on clinical presentation and acaracide treatment of the dog and a relevant importation history. and its place of residence are adequate Findings that could support diagnosis control measures. include thoracic radiography (patchy parenchymal infiltrates, enlarged caudal For cases of tick paralysis associated lobar arteries), echocardiology (parallel with I. holocyclus, early administration hyperechoic lines in the right heart of tick antitoxin serum can result in and pulmonary arteries, indicating improvement of clinical signs within the heartworm cuticle), routine 6–12 hours. Tick paralysis can be fatal: an haematology (eosinophilia, basophilia) Australian survey showed that death was and biochemistry (hyperglobulinaemia) the outcome in 5 percent of cases and was (Figure 6). usually due to paralysis of the respiratory muscles (Atwell, 2008). Antigen-based diagnostic tests give negative results during the initial Dirofilaria immitis – Heartworm pneumonitis syndrome as circulating Worldwide situation: Heartworm antigen and microfilaria are not (Dirofilaria immitis) is present in most 2mm present until 5–6 months or more after countries with temperate, semitropical infestation (Ferasin, 2005). Antigen- or tropical climates, including Australia, Figure 5: Dorsal view of a fully engorged test sensitivity can be low for cats North America, Latin America and Haemaphysalis longicornis (New Zealand cattle because unisex infections are common southern Europe. It is seen more tick). Photo: Qing Hai Fan, MPI. and they rarely have mature worm

6 Surveillance 43 (2) 2016 burdens; sensitivity can also be low in upon them to help keep it free of exotic Heath AC, Hardwick S (2011). The role dogs with light D. immitis infestations pests and diseases. of humans in the importation of ticks to New Zealand: a threat to public health and (Guerrero, 2012). Antibodies are usually If you suspect a notifiable disease or if biosecurity. New Zealand Medical Journal present by five months and can be used you would like to discuss a case with 124(1339), 67–82. to confirm antigen test results, but titres a colleague who has exotic disease persist for several months after worm Atkins C (2015). Overview of Heartworm expertise, please call MPI’s exotic disease Disease (Dirofilariasis). In:The Merck Veterinary death so they are not a reliable indication and pest hotline. Manual. http://www.merckvetmanual.com/ of active infestation. mvm/circulatory_system/heartworm_disease/ Treatment options: Ivermectin and other References overview_of_heartworm_disease.html Accessed 26 April 2016. macrocyclic lactone drugs are effective Anonymous (2009). Cats, dogs and canine semen against larval worms, but not against from all countries – Final import risk analysis. Loth L (2005). Review of exotic tick interceptions Science and Risk Assessment, Ministry for mature adults (Ferasin, 2005). There is in New Zealand since 1980. Surveillance 32(3), Primary Industries, November 2009. www.mpi. 7–9. currently no satisfactory treatment for govt.nz/document-vault/2796 mature heartworm infestations. Arsenical McQuiston JH (2014). Ehrlichiosis and drugs can be used to treat adult worms Anonymous (2013). Ehrlichiosis and Related Infections. In: The Merck Veterinary Anaplasmosis: Zoonotic Species (2013). Iowa . http://www.merckvetmanual.com/mvm/ in dogs, but this must be done with Manual State University. http://www.cfsph.iastate.edu/ generalized_conditions/rickettsial_diseases/ caution as complications with pulmonary Factsheets/pdfs/ehrlichiosis.pdf. Accessed 26 ehrlichiosis_and_related_infections.html embolism can occur. April 2016. Accessed 26 April 2016. The adult heartworm lifespan in cats Atwell R., Campbell FE, Evans EA (2001). Neer TM, Breitschwerdt EB, Greene RT, Lappin is shorter than dogs (usually about Prospective survey of tick paralysis in dogs. MR (2002). Consensus Statement on Ehrlichial two years), so spontaneous recovery Australian Veterinary Journal 79, 412–418. Disease of Small Animals from the Infectious is possible. Many cats are managed Barker SC, Walker AR, Campelo D (2014). Disease Study Group of the ACVIM. Journal of Veterinary Internal Medicine 16: 309–315. conservatively with restricted activity and A list of the 70 species of Australian ticks; corticosteroid therapy, and 25–50 percent diagnostic guides to and species accounts Solano-Gallego L, Koutinas A, Miró G, Cardoso of (paralysis tick), of them may survive with this approach Ixodes holocyclus Ixodes L, Pennisi MG, Ferrer L, Bourdeau P, Oliva G, cornuatus (southern paralysis tick) and Baneth G (2009). Directions for the diagnosis, (Guerrero, 2012). Rhipicephalus australis (Australian cattle tick); clinical staging, treatment and prevention of and consideration of the place of Australia in canine leishmaniosis. Veterinary Parasitology Discussion the evolution of ticks with comments on four 165, 1–18. New Zealand’s geographical isolation and controversial ideas. International Journal of Parasitology 44, 941–953. Tana T (2014). The MPI Animal General robust biosecurity systems ensure that Surveillance Program. Surveillance 41(2), 5–8. incursions of exotic diseases are rare. No Cobb SP, MacDiarmid SC (2014). Animal Health Risk Analysis. In: Encyclopedia of Meat Sciences Vose, D (2008). Risk analysis: A quantitative international border is impenetrable and rd nd guide (3 Ed.). Chichester: John Wiley & Sons. occasionally veterinary practitioners may (2 ed.), Dikeman M and Devine D, Eds. Elsevier, be presented with an unusual case with London, pp. 27–32. World Organisation for Animal Health (2010). an exotic disease differential diagnosis. Ferasin L, Knight D (2005). Filarial infections. Handbook on import risk analysis for animals In: Shaw SE, Day MJ (eds) -borne and animal products: Volume 1 Introduction Vets who work with companion animals, and qualitative risk analysis. Second Edition. livestock and wildlife are the eyes Infectious Diseases of the Dog and Cat. Lippincott, Williams and Wilkins, Baltimore, Paris: World Organisation for Animal Health. and ears of MPI’s animal biosecurity pp. 51–61. http://www.oie.int/doc/ged/D6586.PDF Accessed surveillance system and the country relies 26 April 2016. World Organisation for Animal Health (OIE) (2015). Chapter 2.1. Import risk analysis. In: Terrestrial Animal Health Code, 24th Ed. Paris: World Organisation for Animal Health, pp. 75–79. http://www.oie.int/index. php?id=169&L=0&htmfile=chapitre_import_risk_ analysis.htm Accessed 26 April 2016. World Trade Organization (1995). Agreement on the Application of Sanitary and Phytosanitary Measures. www.wto.org/english/tratop_e/sps_e/ spsagr_e.htm Accessed 26 April 2016.

Thomas Rawdon Principal Adviser Surveillance and Incursion Investigation (Animals and Marine) Investigation and Diagnostic Centres and Response Directorate Ministry for Primary Industries [email protected] Figure 6: Feline heartworm (Dirofilaria immitis) disease – lateral thoracic radiograph showing enlarged caudal lobar pulmonary arteries. Photo: www.merckvetmanual.com.

Surveillance 43 (2) 2016 7 Eve Pleydell Senior Adviser Response Investigation and Diagnostic Centres and Response Directorate Ministry for Primary Industries [email protected]

Kelly Buckle Veterinary Pathologist Surveillance and Incursion Investigation (Animals and Marine) Investigation and Diagnostic Centres and Response Directorate Ministry for Primary Industries [email protected]

Chris Rodwell Senior Adviser Response, Investigation and Diagnostic Centres and Response Directorate Ministry for Primary Industries [email protected]

Stephen Cobb Manager-Biosecurity Risk Analysis (Animals and Aquatic) Biosecurity Science, Food Science and Risk Assessment Ministry for Primary Industries [email protected]

8 Surveillance 43 (2) 2016