Chrysomya bezziana (Old World screw-worm)
Index
- Pictures
- Identity
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Diseases Table
- Distribution Table
- History of Introduction and Spread
- Introductions
- Risk of Introduction
- Pathogen Characteristics
- Habitat List
- Host Animals
- List of Symptoms/Signs
- Climate
- Latitude/Altitude Ranges
- Notes on Natural Enemies
- Pathway Causes
- Pathway Vectors
- Economic Impact
- Environmental Impact
- Risk and Impact Factors
- References
- Contributors
- Distribution Maps
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Top of page| Picture | Title | Caption | Copyright |
|---|---|---|---|
| Oviposition | Chrysomya bezziana (Old World screw-worm); oviposition - females laying eggs on a wounded steer. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Adults mating | Chrysomya bezziana (Old World screw-worm); pair copulating. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Oviposition | Chrysomya bezziana (Old World screw-worm); females ovipositing on wounded steer. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Early stage of myiasis | Chrysomya bezziana (Old World screw-worm); wound myiasis - early stage of myiasis, with second and early third instar larvae of C.bezziana in a feeding aggregation. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Third instar larvae | Chrysomya bezziana (Old World screw-worm); mature third instar larvae in a bovine wound. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Final instar larvae | Chrysomya bezziana (Old World screw-worm); larvae evacuating the wound after completing feeding. | ©DrJ. Philip Spradbery-All Rights Reserved | |
| Myiais | Chrysomya bezziana (Old World screw-worm); myiais of navel of new-born buffalo calf. Papua New Guinea. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis of bovine scrotum following castration. Papua New Guinea. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis of sheep's rectum. Port Moresby, Papua New Guinea. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis of sheep's vulva. Papua New Guinea. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis of dog. Port Moresby, Papua New Guinea. | ©Dr D.P.A. Sands-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis of a cat (Felis catus). Port Moresby, Papua New Guinea. | ©Dr J. Philip Spradbery-All Rights Reserved | |
| Myiasis | Chrysomya bezziana (Old World screw-worm); myiasis in human eye orbit. | ©Dr John Niblett-All Rights Reserved | |
| Infested sheep | Chrysomya bezziana (Old World screw-worm); imported Australian sheep with C.bezziana myiasis. Muscat, Sultanate of Oman. | ©Dr J. Philip Spradbery-All Rights Reserved |
Identity
Top of pagePreferred Scientific Name
- Chrysomya bezziana Villeneuve, 1914
Preferred Common Name
- Old World screw-worm
International Common Names
- English: Old World screwworm; Old World Screw-worm fly; screw worm
English acronym
- OWS
- OWSWF
Summary of Invasiveness
Top of pageThe first specimens of Chrysomya bezziana were recovered from myiases on cattle hosts in the Congo, Central Africa in 1909 (Rovère, 1910). The endemic distribution of C. bezziana includes much of central Africa from Sierra Leone in the west to Kenya in the east and to northern South Africa, and probably widespread in Ethiopia and the Horn of Africa. In the Middle East, C. bezziana is endemic to Saudi Arabia, Iran, United Arab Emirates and Sultanate of Oman (Spradbery and Kirk, 1992; Spradbery et al., 1992) and has been accidentally introduced to Yemen, as well as Bahrain and Kuwait, the latter two countries through shipments of livestock passing the Gulf of Oman en route to ports in the Persian Gulf (Kloft et al., 1981). In 1996, a major outbreak occurred in Iraq, exacerbated by a lack of veterinary response due to United Nations sanctions on the country prevailing at that time. The only live incursion into Australia by C. bezziana was recorded in 1988, when a number of adult flies were recovered in an electrocutor trap aboard a livestock vessel that had just returned from delivering live cattle to Brunei (Rajapaksa and Spradbery, 1989).
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Diptera
- Family: Calliphoridae
- Genus: Chrysomya
- Species: Chrysomya bezziana
Notes on Taxonomy and Nomenclature
Top of pageGlobally, there are two Screw-worm fly species, the Old World SWF (OWS) (Chrysomya bezziana) and the New World SWF (NWS) (Cochliomyia hominivorax) (Spradbery, 1994). The genus Chrysomya contains 11 described species, many of which are important in forensic and medical criminal taxonomy (James, 1947). C. bezziana is the only species in the genus of primary medical importance and is distributed in sub-Saharan Africa, Middle East, Indian subcontinent, SE Asia and New Guinea, where the larvae parasitize warm-blooded animals including livestock and humans. Chrysomya bezziana was first described by Professor Mario Bezzi of Turin, based on material collected from cattle in the Belgian Congo (now CDR) who identified them as Chrysomya megacephala, but later they were correctly identified as a new species by Joseph Villeneuve de Janti, and named Chrysomya bezziana, in honour of Professor Bezzi (Villeneuve, 1914).
Distribution Table
Top of pageThe distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Last updated: 10 Jan 2020History of Introduction and Spread
Top of pageChrysomya bezziana was first described from adults reared from larvae collected in cattle myiases in Kitoboli and Dolo, Belgian Congo (now CDR) by Joseph Rovère, a doctor and veterinarian (Villeneuve, 1914). The endemic distribution of C. bezziana includes much of tropical Africa, Arabia and the Middle East, the Indian subcontinent and SE Asia as far east as New Guinea. Introductions are made possible by the movement of host animals. For example, live sheep exports from Australia to Middle East ports resulted in sheep becoming infested at the port of Muscat in the Sultanate of Oman when unloading animals, followed by their subsequent offloading in Bahrain and Kuwait (Kloftet al., 1981). C. bezziana has been recorded in Australia on one occasion when a returning livestock vessel docked at Darwin after delivering cattle to Brunei. An electrocutor trap was set up on board the vessel after it had cleared customs and quarantine and 7 adult C. bezziana were subsequently captured (Rajapaksa and Spradbery, 1989). A passenger aboard a commercial flight from Sri Lanka to Kuala Lumpur in Malaysia was found to have a C. bezziana infestation (Pillai and Ramalingan, 1984). The accidental introduction of C. bezziana to Iraq in 1996 (Abdul Rassoul et al., 1996; Al-Izzi et al., 1999; Hall et al., 2001; Siddig et al., 2005) resulted in its rapid dispersal throughout the Tigris and Euphrates river systems with approximately 60,000 cases reported in livestock and humans within 2 years, with a mortality rate of 1 per cent in livestock (Spradbery and El-Dessouky, 1998).
Introductions
Top of page| Introduced to | Introduced from | Year | Reason | Introduced by | Established in wild through | References | Notes | |
|---|---|---|---|---|---|---|---|---|
| Natural reproduction | Continuous restocking | |||||||
| Bahrain | Oman | 1970s | Animal production (pathway cause) | Yes | Kloft et al. (1981) | Via live sheep exports to Gulf ports from Australia via Oman | ||
| Iraq | 1996 | Yes | Hall et al. (2001); Siddig et al. (2005) | |||||
| Kuwait | Oman | 1970s | Animal production (pathway cause) | Yes | Kloft et al. (1981) | Via live sheep exports to Gulf ports from Australia via Oman | ||
| Qatar | Oman | 1970s | Animal production (pathway cause) | Yes | Kloft et al. (1981) | Via live sheep exports to Gulf ports from Australia via Oman | ||
| Yemen | 2007 | Yes | Robinson et al. (2009) | |||||
Risk of Introduction
Top of pageThe most likely route for an incursion of Chrysomya bezziana to a new location is via an infested host animal, be it livestock or human. However, adult flies have been intercepted in passenger aircraft and returning livestock vessels arriving in Australian ports (Rajapaksa and Spradbery, 1989). C. bezziana remains present in Bahrain, Kuwait, Iraq and Yemen where it was accidentally introduced, but no further countries have experienced incursions resulting in successful colonization. Australia maintains an official state of awareness and preparedness with respect to a potential C. bezziana incursion (Animal Health Australia AUSVETPLAN, 2007).
Pathogen Characteristics
Top of pageDetailed descriptions of life stages and their morphology in C. bezziana and associated species are given in Spradbery (2002a) and geographical races of C. bezziana are described in Wardhana et al. (2012a).
Eggs: The egg is white, 1.25 mm long and 0.26 mm in diameter with a cylindrical shape, rounded at both ends with the anterior end more tapered. The eggs are laid in a mass of three or more layers thick, glued together in parallel, giving the appearance of a shingled roof.
Larvae: 1st, 2nd and 3rd instar larvae are white to cream coloured 1.6 mm, 3.5-5.5 mm and 6.1-15.7 mm long, respectively, with characteristic bands of spines on most segments. The thorn-like spines are black with a single point. Prominent mouth hooks and heavily sclerotized peritreme surrounding the posterior spiracles with three slit-like openings.
Pupae: Colour changes from deep pink to dark brown as the larval skin changes into the puparium shell through sclerotization. Puparia are characterized by their barrel-shape and retaining many of the external morphological characters of the final stage larva such as spines and spiracles.
Adult fly: The adult fly is 8-12 mm in length and green to blue in colour.
Host Animals
Top of page| Animal name | Context | Life stage | System |
|---|---|---|---|
| Bos indicus (zebu) | Domesticated host, Wild host | Cattle & Buffaloes: All Stages | |
| Bos taurus (cattle) | Domesticated host, Wild host | Cattle & Buffaloes: All Stages | |
| Bubalus bubalis (Asian water buffalo) | Domesticated host, Wild host | Cattle & Buffaloes: All Stages | |
| Canis familiaris (dogs) | Domesticated host, Wild host | ||
| Capra hircus (goats) | Domesticated host, Wild host | Sheep & Goats: All Stages | |
| Cervidae | Wild host | ||
| Elephas maximus | |||
| Gallus gallus domesticus (chickens) | Domesticated host | Poultry: Young poultry|Poultry/Mature female|Poultry/Cockerel|Poultry/Mature male | |
| Homo sapiens | |||
| Loxodonta africana | |||
| Ovis aries (sheep) | Domesticated host, Wild host | Sheep & Goats: All Stages | |
| Panthera leo (lion) | |||
| Sus scrofa (pigs) | Domesticated host, Wild host | Pigs: All Stages |
List of Symptoms/Signs
Top of page| Sign | Life Stages | Type |
|---|---|---|
| General Signs / Cyanosis, blue skin or membranes | Sign | |
| General Signs / Inability to stand, downer, prostration | Sign | |
| General Signs / Swelling mass penis, prepuce, testes, scrotum | Sign | |
| Nervous Signs / Dullness, depression, lethargy, depressed, lethargic, listless | Sign | |
| Pain / Discomfort Signs / Skin pain | Sign | |
| Reproductive Signs / Paraphimosis or priapism, inability to retract penis | Sign | |
| Reproductive Signs / Phimosis | Sign | |
| Skin / Integumentary Signs / Alopecia, thinning, shedding, easily epilated, loss of, hair | Sign | |
| Skin / Integumentary Signs / Foul odor skin, smell | Sign | |
| Skin / Integumentary Signs / Parasite visible, skin, hair, feathers | Sign | |
| Skin / Integumentary Signs / Skin erythema, inflammation, redness | Sign | |
| Skin / Integumentary Signs / Skin necrosis, sloughing, gangrene | Sign | |
| Skin / Integumentary Signs / Skin ulcer, erosion, excoriation | Sign | |
| Urinary Signs / Dysuria, difficult urination, stranguria | Sign |
Climate
Top of page| Climate | Status | Description | Remark |
|---|---|---|---|
| A - Tropical/Megathermal climate | Preferred | Average temp. of coolest month > 18°C, > 1500mm precipitation annually | |
| Af - Tropical rainforest climate | Preferred | > 60mm precipitation per month | |
| Am - Tropical monsoon climate | Preferred | Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25])) | |
| As - Tropical savanna climate with dry summer | Preferred | < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25]) | |
| Aw - Tropical wet and dry savanna climate | Preferred | < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25]) | |
| B - Dry (arid and semi-arid) | Tolerated | < 860mm precipitation annually | |
| C - Temperate/Mesothermal climate | Tolerated | Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C |
Latitude/Altitude Ranges
Top of page| Latitude North (°N) | Latitude South (°S) | Altitude Lower (m) | Altitude Upper (m) |
|---|---|---|---|
| 35 | 27 |
Notes on Natural Enemies
Top of pageA species of Syrphophagus (Hymenoptera: Encyrtidae), a generalist parasitoid of fly puparia, was accidentally introduced to laboratory cultures of Chrysomya bezziana in Papua New Guinea in 1975 (Spradbery, unpublished observations). No other parasitoids of C. bezziana have been reported. General insect predators such as birds may take adult C. bezziana in the field but no observations have been reported. Rats have been recorded feeding on mature C. bezziana larvae after they dropped from infested cattle (Spradbery, unpublished observations).
Pathway Causes
Top of page| Cause | Notes | Long Distance | Local | References |
|---|---|---|---|---|
| Animal production | Movements of infested humans, stock or wildlife | Yes | Yes | Spradbery, 1994 |
Pathway Vectors
Top of page| Vector | Notes | Long Distance | Local | References |
|---|---|---|---|---|
| Aircraft | Adults | Yes | Rajapaksa and Spradbery, 1989 | |
| Livestock | OWS Larvae via live sheep trade; OWS Adults via returning, empty livestock ships | Yes | Yes | Kloft et al., 1981; Rajapaksa and Spradbery, 1989 |
Economic Impact
Top of pageIn Zimbabwe (Rhodesia) Chrysomya bezziana is, with the exception of the tsetse fly, Glossina morsitans, the most important insect pest of cattle, horses, dogs and other domestic animals (Cuthbertson, 1933). When the tick control programme broke down during the 1973-1978 guerilla war in Rhodesia, more than 300,000 livestock were lost, the majority due to C. bezziana infestations (Norval, 1978). C. bezziana is considered a major obstacle to large-scale beef production in Malaysia (Basset and Kadir 1982). The economic impact of the 1996 Iraq incursion included an estimated FAO/AOAD budget at the time of US$8,555,000 to counter the invasion (Spradbery and El-Dessouky, 1998). The cost of a C. bezziana incursion resulting in the establishment of the pest in Australia was estimated as high as $AUD900 million per annum a decade ago (Kwabena Anaman in Spradbery, 2002b). The social impact of livestock production losses is matched by the misery of human infestations caused by C. bezziana, especially among children and the aged and infirm. The adverse impacts on wildlife would also be considerable.
Environmental Impact
Top of pageImpact on Habitats
Generally low, if any, measureable adverse impacts on habitat.
Impact on Biodiversity
Because of its wide host range, Chrysomya bezziana is unlikely to have a major impact on biodiversity although, in the United States, the New World Screw-worm fly species killed 80 per cent of fawns of one species of deer, the white-tailed deer (Odocoileus virginianus texanus) in some years (Fuller, 1962). The introduction of livestock breeds naïve for screw-worm fly into endemic areas such as Antipodean sheep to India and Papua New Guinea can be catastrophic for the new arrivals (Basset and Kadir, 1982; Spradbery, unpublished observations).
Risk and Impact Factors
Top of page Invasiveness- Invasive in its native range
- Proved invasive outside its native range
- Has a broad native range
- Is a habitat generalist
- Tolerant of shade
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Benefits from human association (i.e. it is a human commensal)
- Fast growing
- Has high reproductive potential
- Host damage
- Negatively impacts agriculture
- Negatively impacts human health
- Negatively impacts animal health
- Negatively impacts livelihoods
- Transportation disruption
- Parasitism (incl. parasitoid)
- Pathogenic
- Highly likely to be transported internationally accidentally
- Difficult/costly to control
References
Top of pageAbdul Rassoul MS; Ali HA; Jassim FA, 1996. Notes on Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), first recorded from Iraq. Bulletin of the Iraq Natural History Museum, 8:113-115.
Al-Izzi MAJ; Al-Taweel AA; Jassim FA, 1999. Epidemiology and rearing of Old World screwworm, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) in Iraq. Iraqi Journal of Agriculture, 4:153-160.
Animal Health Australia, 2007. Disease Strategy: Screw-worm fly (Version 3). Australian Veterinary Emergency Plan (AUSVETPLAN), Edition 3. Canberra, ACT, Australia: Primary Industries Ministerial Council, 60 pp.
Beckett S; Spradbery JP; Urech R; James; P; Green P; Welch M, 2014. Old World Screw-worm Fly: Risk of Entry into Australia and Surveillance Requirements. Report for Animal Health Australia. Canberra, Australia: Animal Health Australia, 192 pp.
Fuller G, 1962. How screwworm eradication will affect wildlife. The Cattleman, 48:82-84.
James P; Wardhana A; Brown G; Urech R, 2014. Chemical containment and eradication of screw-worm incursions in Australia. Report to Meat and Livestock Australia. Sydney, Australia: Meat and Livestock Australia, 37 pp.
James PJ; Green PE; Urech R; Spradbery JP, 2005. Chemicals for control of the Old World screw-worm fly Chrysomya bezziana in Australia. Report to Department of Agriculture Fisheries and Forestry. Canberra, Australia: Department of Agriculture Fisheries and Forestry, 40 pp.
Mahon RJ, 2002. The Malaysian project - entomological report. In: Proceedings of the Screw-worm Fly Emergency Preparedness Conference, Canberra, Australia, November 2001., Australia: Agriculture, Fisheries and Forestry - Australia, 140-151.
Ng KH; Yip KT; Choi CH; Yeung KH; Auyeung TW; Tsang AC; Chow L; Que TL, 2003. A case of oral myiasis due to Chrysomya bezziana. Hong Kong Medical Journal, 9:454-456.
Norris KR; Murray MD, 1964. Notes on the screw-worm fly Chrysomya bezziana (Diptera: Calliphoridae) as a pest of cattle in Papua New Guinea. CSIRO Division of Entomology Technical Paper No. 6. Melbourne, Australia: CSIRO, 26 pp.
OIE Handistatus, 2002. World Animal Health Publication and Handistatus II (dataset for 2001). Paris, France: Office International des Epizooties.
OIE Handistatus, 2003. World Animal Health Publication and Handistatus II (dataset for 2002). Paris, France: Office International des Epizooties.
OIE Handistatus, 2004. World Animal Health Publication and Handistatus II (data set for 2003). Paris, France: Office International des Epizooties.
OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (data set for 2004). Paris, France: Office International des Epizooties.
OIE, 2009. World Animal Health Information Database - Version: 1.4. World Animal Health Information Database. Paris, France: World Organisation for Animal Health. http://www.oie.int
Rovere J, 1910. Etude de larvae cuticoles appartenant au genre Chrysomyia, observées au Congo Belge. Bulletin Agricole du Congo Belge, 1:26-35.
Spradbery JP, 1992. Studies on the prepupal and puparial stages of the Old World screw-worm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae). CSIRO Division of Entomology Technical Report No. 49., Australia: CSIRO, 24 pp.
Spradbery JP, 2002. A Manual for the Diagnosis of Screw-worm Fly. CSIRO Division of Entomology Publication, 2nd edition. Canberra, ACT, Australia: Agriculture, Fisheries and Forestry - Australia, iii + 70 pp.
Spradbery JP, 2002. The Screwworm Fly Problem: A Background Briefing. In: Proceedings of the Screw-worm Fly Emergency Preparedness Conference, Canberra, Australia, November 2001., Australia: Agriculture, Fisheries and Forestry - Australia, 114-119.
Spradbery JP; El-Dessouky F, 1998. Emergency Assistance for Screw-worm Fly Control in Iraq and the Middle East Region. Report on a mission to the Republic of Iraq and neighbouring countries for the Food and Agriculture Organisation of the United Nations. FAO Project code: TCP/IRQ/6611. Italy, Rome: FAO, 34 pp.
Villeneuve J, 1914. Etude sur quelques types de myodaires supérieurs. Revue Zoologique et Botanique Africaine, 3:429-441.
Wardhana AH, 2006. Chrysomya bezziana Penyebab myiasis pada hewan dan Mausia: permasalahan dan penanggulangannya. Wartazoa, 16:146-159.
Wardhaugh KG; Mahon RJ, 2002. Insecticides as an integral part of the sterile insect technique for the control of Old World screw-worm fly, Chrysomya bezziana. In: Proceedings of the Screw-worm Fly Emergency Preparedness Conference, Canberra, Australia, November 2001., Australia: Agriculture, Fisheries and Forestry - Australia, 103-110.
Distribution References
CABI Data Mining, 2001. CAB Abstracts Data Mining.,
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Ng KH, Yip KT, Choi CH, Yeung KH, Auyeung TW, Tsang AC, Chow L, Que TL, 2003. A case of oral myiasis due to Chrysomya bezziana. In: Hong Kong Medical Journal, 9 454-456.
Rovere J, 1910. (Etude de larvae cuticoles appartenant au genre Chrysomyia, observées au Congo Belge). In: Bulletin Agricole du Congo Belge, 1 26-35.
Contributors
Top of page21/07/15 Original text by:
Dr J. Philip Spradbery, XCS Consulting Pty Ltd, GPO Box 2566, Canberra, ACT 2600, Australia.
Distribution Maps
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