Ioz Disease Risk Analysis Sheets

Appendix A

IoZ disease risk analysis sheets

Summary of IoZ findings

Of the 11 hazards investigated, two were discounted as hazards with the remaining identified as carrier hazards (5) or destination and population hazards (2). Of the carrier hazards two were assigned a low risk estimation, one was assigned a low-medium risk estimation and four were estimated as being of medium risk. There was one destination and population hazard assigned a very low-low risk estimation and one of medium risk estimation.

Aspergillus fumigatus

TYPE OF HAZARD

Carrier

JUSTIFICATION OF HAZARD

Hihi may carry Aspergillus fumigatus spores in airsacs and lungs without symptoms (Converse 2007), when stressed disease, aspergillosis, can occur often resulting in death (Alley et al. 1999).

RELEASE ASSESSMENT

Aspergillus fumigatus spores are inhaled and settle out into the airsacs and lungs of hihi, where they can remain dormant, or form fungal plaques (Converse 2007).There is high likelihood of the hihi being infected when translocated as it is an ubiquitous fungus with an almost worldwide distribution (Converse 2007) which likes modified habitats (Perrott & Armstrong 2011). Tiritiri Matangi is a modified habitat, until the early 1980s it was cleared farmland, since then it has been extensively re-vegetated and is actively managed (Frost et al. 2012).

EXPOSURE ASSESSMENT

Hihi may be exposed and develop disease during the quarantine of the translocation process where they will be kept in close quarters with other hihi, as well as being stressed by capture, restraint and sampling procedures. Lowering of host immunocompetence is a factor in development of disease (Converse 2007; Alley et al. 1999). However, only birds which are part of the translocation project are likely to be affected as it is not a contagious disease. A.fumigatus spores are inhaled from the environment. Hihi can be exposed during their normal daily activities, foraging, roosting and nesting in tree cavities. There is high likelihood of the exposure occurring as A.fumigatus is an ubiquitous fungus, and is particularly fond of highly modified environments such as Bushy Park (Perrott & Armstrong 2011). Aspergillosis is a non-infectious disease with no documented transmission between animals (Converse 2007) and so dissemination is very unlikely. There is a suggestion of a seasonal bias during the winter months for development of aspergillosis in New Zealand (Cork et al. 1999).

CONSEQUENCE ASSESSMENT

There is high likelihood that at least one hihi will be infected, or may become infected due to the translocation procedure. Aspergillosis is the most commonly diagnosed cause of mortality in hihi [24.4% in wild birds, 23.6% wild and captive combined 2001-2008](Ewen et al. 2012). If it becomes a large scale problem for hihi, there would likely be failure of the translocation, as eventually occurred with the Mokoia Island population (Alley et al. 1999; Armstrong et al. 2007). Apart from failure of translocation, hihi contracting aspergillosis would have little environmental consequence, other than a reduction in ecosystem services that hihi provide as part of the New Zealand native fauna (Kelly et al. 2010).

There is low to moderate likelihood of these consequences.

RISK ESTIMATION

There is high likelihood of hihi being infected when translocated to Bushy Park. There is high likelihood of exposure during quarantine and translocation, however other birds have negligible likelihood of exposure due to the translocation of hihi. There is high likelihood of at least one hihi becoming infected, and low to moderate likelihood of population level consequences. The overall risk estimation is high.

RISK EVALUATION

The risk estimation is high, sanitary measures are justified.

OPTION EVALUATION

Practical:

In a captive situation diagnostic methods for A. fumigatus infection includes fungal culture from airsacs and airways, white blood cell count (WBCC), radiographs of respiratory system, biopsy and necropsy. In a field situation only indirect methods such as WBCC may be practical. Post mortem examinations should be carried out on all hihi found dead. Maintaining a clean, dry environment with limited vegetation which may carry spores would reduce the likelihood of greater exposure during quarantine. Current translocation protocol for the hihi includes administration of itraconazole (Sporonoxâ) (5mg/kg body weight/day) from day 3 to release from quarantine(Frost et al. 2012). This should be done, in conjunction with reduction in stress by minimising handling.

Ideal situation:

Spore counts of the permanent quarantine aviaries should be performed annually, possibly at the end of each translocation. To determine the relative differences, if any, between the source and destination sites fungal spore counts should be done at each site (see Perrott & Armstrong 2011), and management decisions taken in light of those findings. As there is a potential seasonal bias towards the winter months, it may be best to do spore counts in winter.

Alley, M.R., Castro, I & Hunter, J.E., 1999. Aspergillosis in hihi (Notiomystis cincta) on Mokoia Island. New Zealand Veterinary Journal, 47(3), pp.88-91. Available at: http://www.ncbi.nlm.nih.gov/pubmed/16032079.

Armstrong, D.P., Castro, Isabel & Griffiths, R., 2007. Using adaptive management to determine requirements of re-introduced populations: the case of the New Zealand hihi. Journal of Applied Ecology, 44(5), pp.953-962. Available at: http://doi.wiley.com/10.1111/j.1365-2664.2007.01320.x [Accessed March 9, 2012].

Converse, K.A., 2007. Aspergillosis. In N. J. Thomas, D. B. Hunter, & C. T. Atkinson, eds. Infectious Diseases of Wild Birds. Ames, Iowa USA: Blackwell Publishing Ltd., pp. 360-374.

Cork, S.C. et al., 1999. Aspergillosis and other causes of mortality in the stitchbird in New Zealand. Journal of Wildlife Diseases, 35(3), pp.481-6. Available at: http://www.ncbi.nlm.nih.gov/pubmed/10479082.

Ewen, J.G. et al., 2012. Parasite management in translocations: lessons from a threatened New Zealand bird. Oryx, FirstView, pp.1-11. Available at: href="http://dx.doi.org/10.1017/S0030605311001281.

Frost, P. et al., 2012. Bushy Park Hihi Translocation Proposal 2012. , p.28.

Kelly, D. et al., 2010. Mutualisms with the wreckage of an avifauna: the status of bird pollination and fruit-dispersal in New Zealand. New Zealand Journal Of Ecology, 34(1), pp.66-85.

Perrott, J.K. & Armstrong, D.P., 2011. Aspergillus fumigatus densities in relation to forest succession and edge effects: implications for wildlife health in modified environments. EcoHealth, 8(3), pp.290-300. Available at: http://www.ncbi.nlm.nih.gov/pubmed/22076057 [Accessed May 9, 2012].

Plasmodium relictum

TYPE OF HAZARD

Carrier

JUSTIFICATION OF HAZARD

Plasmodium relictum GRW4 associated disease has been reported as a cause of death in one hihi for the first time recently (Howe et al. 2012) and the parasite may be carried by hihi between the source and destination. The stress of translocation (capture, handling, quarantine and transport) may precipitate disease due to the parasite (Parker et al. 2012).

RELEASE ASSESSMENT

Infection with Plasmodium spp. depends on a hihi being bitten by a competent vector which has already taken a blood meal from another infected bird. Although many mosquitoes are capable of carrying the parasite in laboratory experiments, only three species have been found to be infected in a wild situation in California and Hawai’i (C.quinquefasciatus, C.tarsalis and C.stigmatasoma) (Atkinson 2008). However, there is ongoing research which suggests that there are other competent mosquito species as vectors in the south-west Pacific (Ishtiaq et al. 2008). C. quinquefasciatus is known to live on North Island, and is working down to South Island as well (Holder 1999; Tompkins & Gleeson 2006), and there are reports of avian malaria having effects on native New Zealand birds (Howe et al. 2012; Derraik et al. 2008). There is likely to be a seasonal aspect to the transmission of the parasite corresponding to the natural fluctuations in mosquito presence, and related to the breeding season for the avian host when recently fledged birds are more numerous in the population (Atkinson 2008). Hihi on Tiritiri Matangi may be exposed to Plasmodium spp. via competent vectors from introduced blackbirds (Turdus merula) and European song thrush (Turdus philomelos) which have been found to have Plasmodium spp. infections on the island (Howe et al. 2012). There is a low likelihood of the hihi being infected when translocated because the prevalence of infection and disease in hihi is apparently low.

EXPOSURE ASSESSMENT

Hihi may already be infected at the source site, and, following translocation, without medical intervention it is highly unlikely that a bird could remove the intracellular parasite, and therefore hihi will remain exposed. There is a low likelihood of dissemination of Plasmodium spp through vectors feeding on infected hihi and then on other animals because the prevalence of infection in hihi is likely to be low.

CONSEQUENCE ASSESSMENT

There is low likelihood that at least one translocated hihi will be infected when at the destination (of 261 hihi sampled between 2003 and 2006 none were positive [Ewen et al 2012]; one death in 2011 attributable to avian malaria [Howe 2012]. The biological and environmental consequences will likely be limited to the loss of a small number of hihi. Economic consequences relate to the financial input for translocation. There is a low likelihood of the occurrence of these consequences.

RISK ESTIMATION

Low likelihood of entry.

Low likelihood of exposure.

Low likelihood of consequences occurring

Overall low risk estimation.

RISK EVALUATION

Risk estimation is low, not negligible. Management measures are justified.

OPTION EVALUATION

Current gold standard detection is by blood smear evaluation for intracellular parasites in erythrocytes (Atkinson 2008), however advances in molecular detection techniques through the use of PCR have increased detection rates, although chronic infections may still be below detectable levels (Fallon et al. 2003; Atkinson 2008). Any heavily infected birds could be identified through screening of blood samples and not included in the translocated population. Birds appear to be unable to completely eliminate infection of Plasmodium spp. (Atkinson 2008) and as some infections may be undetectable even by PCR there is a possibility that infected birds may be translocated, however, screening birds with both microscopy and molecular techniques should reduce the likelihood of infected birds being moved. PCR may be unfeasible given time, expense and increased stress levels to the birds by increasing length of quarantine.

Atkinson, C.T., 2008. Avian Malaria. In C. T. Atkinson, N. J. Thomas, & D. B. Hunter, eds. Parasitic Diseases of Wild Birds. Ames, Iowa USA: Wiley-Blackwell, US., pp. 35-53.

Derraik, J.G.B. et al., 2008. Epidemiology of an avian malaria outbreak in a native bird species ( Mohoua ochrocephala ) in New Zealand. Journal of the Royal Society of New Zealand, 38(4), pp.237-242.

Fallon, S.M. et al., 2003. Detecting avian malaria: an improved polymerase chain reaction diagnostic. The Journal of Parasitology, 89(5), pp.1044-7. Available at: http://www.ncbi.nlm.nih.gov/pubmed/14627154.

Holder, P., 1999. The mosquitoes of New Zealand and their animal disease significance. Surveillance, 26(4), pp.12-15.

Howe, L. et al., 2012. Malaria parasites (Plasmodium spp.) infecting introduced, native and endemic New Zealand birds. Parasitology Research, 110, pp.913-923.

Ishtiaq, F. et al., 2008. Avian haematozoan parasites and their associations with mosquitoes across Southwest Pacific Islands. Molecular Ecology, 17, pp.4545-55. Available at: http://www.ncbi.nlm.nih.gov/pubmed/18986499 [Accessed April 23, 2012].

Parker, K.A. et al., 2012. The theory and practice of catching, holding, moving and releasing animals. In J. G. Ewen et al., eds. Reintroduction Biology: integrating science and management. Oxford, UK: Wiley-Blackwell, UK., p. 105.

Tompkins, D.M. & Gleeson, D.M., 2006. Relationship between avian malaria distribution and an exotic invasive mosquito in New Zealand. Journal of the Royal SOciety of New Zealand, 36(2), pp.51-62.

Avian poxvirus (Poxvirus avium)

TYPE OF HAZARD

Carrier

JUSTIFICATION OF HAZARD

Many native New Zealand birds are infected (Alley 2002) and multiple clades are found in New Zealand (Ha et al 2011). Not confirmed in hihi to date, but there is a possibility of subclinical infection which is carried from source to destination.

RELEASE ASSESSMENT

Avipox virus is transmissible through multiple pathways, with the most common means of infection being via biting insects which act as mechanical vectors (C. van Riper & Forrester 2007). Poxvirus can remain viable in exfoliated scabs, on perches and be passed by direct contact to an infected bird (C. van Riper & Forrester 2007; Ritchie 1995). Avian poxvirus infection can occur at all times of the year in wild birds, but in temperate areas such as North Island, New Zealand, the biting insect vector numbers tend to lead to most infections occurring in spring, summer and early autumn (C. van Riper & Forrester 2007).

Multiple factors affect transmission, the most important of which are host density, host susceptibility and vector numbers within an environment at a particular time (C. van Riper et al. 2002). A hihi could become infected from contact with other infected birds, contact with infected biological material at feeding sites (e.g. shed scabs) or through mechanical vectors. In addition, hihi could become infected from contact with contaminated mist nets or the temporary housing for quarantine screening. There is a low likelihood of the hihi being infected when translocated because infection has not to date been recorded.

EXPOSURE ASSESSMENT

If infected when translocated, the hihi may remain infected during quarantine and after release and therefore remain exposed. There is low likelihood of the exposure occurring because infection wth avian poxvirus has not to date been recorded. There is a low likelihood of dissemination through shedding the virus at the destination.

CONSEQUENCE ASSESSMENT

There is a low likelihood that at least one hihi becomes infected. Poxvirus infection manifests in two common forms, the cutaneous wart-like lesions usually seen on the non-feathered parts of the body such as the beak, feet, legs and head (C. van Riper & Forrester 2007; Ha et al. 2011; Alley et al. 2010) or, a diphtheroid form with lesions on the mucous membranes, often coalescing and forming a pseudomembrane (C. van Riper & Forrester 2007; Ha et al. 2011; Tripathy et al. 2000). The latter form is associated with high mortality (Tripathy et al. 2000). There is low likelihood of the occurrence of disease and mortality because disease has not been recorded in hihi to date. Therefore the biological, environmental and economic consequences are low and limited to effects on the viability of the reintroduction.

RISK ESTIMATION

There is low likelihood of entry.

There is low likelihood of exposure of susceptible birds

The likelihood of biological and economic consequences is low.

Overall risk estimation is low.

RISK EVALUATION

Risk estimation is low, not negligible. Sanitary measures may be justified.