Import risk analysis: Llamas (Lama glama) and alpacas (Vicugna ...

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37. Screwworm and other myiasis infestations 37.1. HAZARD IDENTIFICATION 37.1.1. Aetiological agent Myiasis is a disease caused by the invasion of the tissues or open cavities (e.g. external ears, mouth, nares) of animals by dipteran larvae (Acha & Szyfres 1987). There are many species of fly that cause myiasis and camelids are susceptible to attacks from these. The fly and blowfly species that (Wernery & Kaaden 2002) list as infesting camelids are: Cochliomyia hominivorax, Phormia spp., Calliphora spp., Phaenicia and Lucilia spp. The nasal bot fly usually associated with cervids, Cephenemyia spp. (family Oestridae) is also listed (Wernery & Kaaden 2002). Other flies that could cause opportunistic myiasis infestations in camelids include: Dermatobia hominis, (Acha & Szyfres 1987) and Wohlfahrtia spp. 37.1.2. OIE list New World screwworm (Cochliomyia hominivorax) is listed under diseases of multiple species (OIE 2009). 37.1.3. New Zealand status Cochliomyia hominivorax is listed as an unwanted, notifiable organism. The following species are listed as exotic: Calliphora albifrontalis, C. auger, C. imperialis, and C. nociva. Atherigona poecilopoda, A. excisa and A. orientalis are listed as unwanted (Ministry of Agriculture & Forestry 2009). Cephenemyia spp. (cervid nasal bot fly), Dermatobia spp. and Wohlfahrtia spp. are not listed, but are considered to be exotic. 37.1.4. Epidemiology The New World screwworm fly (NWS) Cochliomyia homnivorax is an obligate parasite of warm-blooded animals, including humans and rarely birds. It is a blowfly of the family Calliphoridae, but unlike most other species of blowfly, screwworms lay their eggs at the edges of wounds on living mammals or at their body cavities. The eggs hatch within 24 hours and the larvae (maggots) that are screw-shaped burrow into the wound in a characteristic screwworm fashion. This results in severe tissue destruction and infested wounds emit an odour that is highly attractive to other gravid female flies (Acha & Szyfres 1987). If untreated, the destructive activity of the larvae may lead to the death of the animal within a very short time. 142 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand
The larvae reach maturity about 4-8 days after hatching from the egg and leave the wound, falling to the ground into which they burrow and pupate. Adult flies emerge from the pupae in 1 week (at 28�C) to 2 months time dependent on temperature and humidity (Acha & Szyfres 1987; Ausvetplan 1996). Freezing or sustained soil temperatures of 8°C or less kill the pupae (Merck 2006). The optimal temperature range for the fly is 20-30�C and this has had a major influence on their distribution. Flies will not move at temperatures below 10�C, and in the range 10-16�C they are very sluggish and probably will not mate. At no stage in the fly's lifecycle is it resistant to freezing and over-wintering in frost areas does not occur (Ausvetplan 1996). The NWS fly is endemic in parts of Central and South America as far south as Argentina. It has been eliminated from the USA, Mexico and several Central American countries, where it was previously endemic, by use of the sterile insect technique. NWS has never established in Australia. Dermatobia hominis, the tropical warble fly, lives in humid forested areas and is one of the most important parasites of cattle in Latin America, where it is distributed between southern Mexico and northern Argentina (Acha & Szyfres 1987). Larval stages are found in many hosts, including humans (Soulsby 1968). The adult fly fastens its eggs to different types of insects of which 49 (mostly mosquitoes and muscoid flies) have been described as vectors of D. hominis in Latin America. These vectors then transport the eggs to warmblooded hosts where they hatch as the insect vector feeds. The warble fly larvae penetrate the skin of the animal within a few minutes of hatching and remain in the subcutaneous tissue for 4-18 weeks (Acha & Szyfres 1987) where they form ‘warbles’ which are connected by breathing holes through the skin to the air. When mature, the larvae leave the host and drop to the ground, burrow, and pupate (Soulsby 1968). The gray flesh fly, Wohlfahrtia vigil causes cutaneous myiasis in North America. Larval stages are maggot-like in appearance and are adapted to maintain an attachment to living tissues with strongly developed oral hooks. Wohlfahrtia vigil is larviparous i.e. it deposits larvae (not eggs) on healthy, uninjured skin of suitable hosts. Larvae penetrate the unbroken skin and form a boil-like swelling. Development to the infective third-larval stage is usually completed in 9-14 days. The parasites then drop to the ground and pupate, approximately 11-18 days later, depending on temperature. W. magnifica occurs in the European and African Mediterranean area, the Middle East, Russia and China. The fly is attracted to open wounds and, being larviparous, deposits larvae in these wounds. It is an important disease of sheep in southern parts of Russia (Acha & Szyfres 1987). The following larval dipterans are often referred to as facultative myiasis-producing flies: Musca domestica (the house flies), Calliphora, Phaenicia, Lucilia, and Phormia spp. (the blowflies or bottleflies) and Sarcophaga spp. (the flesh flies). Their adult stages are synanthropic flies, i.e. they are often associated with human dwellings and readily fly from faeces to food. Larval stages are usually associated with skin wounds of any animal that has become contaminated with bacteria or with a matted hair coat contaminated with faeces. In facultative myiasis, the adult flies are attracted to a moist wound, skin lesion, or soiled hair coat. As adult female flies feed in these sites, they lay eggs. The eggs hatch, MAF Biosecurity New Zealand Import risk analysis: Llamas and alpacas from specified countries ● 143
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Import risk analysis: Llamas (Lama
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MAF Biosecurity New Zealand Pastora
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CONTENTS Executive Summary 1 1. Int
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Acronyms CDC United States Centers
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Executive Summary This risk analysi
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1. Introduction The importation of
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Figure 1. The risk analysis process
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Following public consultation on th
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Disease agent Foot and mouth diseas
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Disease agent PROTOZOA Eimeria alpa
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Bacteria, rickettsias and spirochae
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McKenna PB (2009). An updated check
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6. African horse sickness virus 6.1
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7. Bluetongue virus 7.1. HAZARD IDE
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8. Borna virus 8.1. HAZARD IDENTIFI
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8.2.2. Risk estimation Since entry
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It has been suggested that as many
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Therefore, since the the consequenc
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Givens MD, Heath AM, Brock KV, Brod
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10. Bovine herpesvirus type 1 10.1.
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10.2.2. Exposure assessment Importe
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Bartha A, Haidu G, Aldassy P, Paczo
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11. Epizootic haemorrhagic disease
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12. Eastern equine encephalitis vir
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13. Equine herpesvirus type 1 13.1.
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13.2.2. Exposure assessment Assumin
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Davison AJ, Erberle R, Hayward GS,
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1993). According to Fowler (1992),
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Veterinary Authorities should requi
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15. Louping-ill virus 15.1. HAZARD
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16. Rabies virus 16.1. HAZARD IDENT
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� Rabies is a serious zoonotic di
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17. Vesicular stomatitis virus 17.1
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incubation period of the disease. T
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quarantined with protection from in
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Pharo HJ (1999). Vesicular stomatit
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18.1.5. Hazard identification concl
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necessarily be competent vectors, a
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20. Bacillus anthracis 20.1. HAZARD
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20.3. RISK MANAGEMENT 20.3.1. Optio
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21. Brucella spp. 21.1. HAZARD IDEN
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21.2.4. Risk estimation Since entry
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Gilsdorf MJ, Thoen CO, Temple RM, G
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References References marked * were
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Serological tests include the compl
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with negative results using the com
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24. Coxiella burnetii 24.1. HAZARD
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� Although quarantine is not suit
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25. Leptospira serovars 25.1. HAZAR
Page 99 and 100: immune response is a low titre that
Page 101 and 102: Retention of this empty Chapter, wi
Page 103 and 104: 26. Mycobacterium bovis 26.1. HAZAR
Page 105 and 106: 26.3. RISK MANAGEMENT 26.3.1. Optio
Page 107 and 108: References References marked * were
Page 109 and 110: without any measures for detecting
Page 111 and 112: References References marked * were
Page 113 and 114: Animals become septicaemic a few ho
Page 115 and 116: 29. Salmonella spp. 29.1. HAZARD ID
Page 117 and 118: animals and sporadic cases of salmo
Page 119 and 120: Hansen KR, Nielsen LR, Lind P (2006
Page 121 and 122: Camelidae diseases, or as transmitt
Page 123 and 124: 32. Trypanosoma spp. 32.1. HAZARD I
Page 125 and 126: T. evansi and T. vivax occur in Sou
Page 127 and 128: 5. Animals to be imported could be
Page 129 and 130: (Kittelberger et al 2002) and is th
Page 131 and 132: � The role of an IHS is to specif
Page 133 and 134: 34. Internal parasites 34.1. HAZARD
Page 135 and 136: 34.1.4.2. Trematodes The following
Page 137 and 138: 34.2.4. Risk estimation Since entry
Page 139 and 140: 35. Mites, lice and fleas 35.1. HAZ
Page 141 and 142: 35.2. RISK ASSESSMENT 35.2.1. Entry
Page 143 and 144: N.B. This measure reflects the curr
Page 145 and 146: Hard ticks (Ixodidae) have a lifecy
Page 147 and 148: 1. Camelids could be treated with p
Page 149: the Eastern Cape and North-West Pro
Page 153 and 154: exploration, debriding and flushing
Page 155 and 156: a. all animals have been re-examine
Page 157 and 158: 38. Weeds and seeds 38.1. HAZARD ID
Page 159 and 160: edding materials include wood shavi
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