Outbreak of Type C Botulism in Birds and Mammals in the Emilia Romagna Region, Northern Italy Author(s): Francesco Defilippo, Andrea Luppi, Giulia Maioli, Dario Marzi, Maria Cristina Fontana, Federica Paoli, Paolo Bonilauri, Michele Dottori, and Giuseppe Merialdi Source: Journal of Wildlife Diseases, 49(4):1042-1046. Published By: Wildlife Disease Association DOI: http://dx.doi.org/10.7589/2013-03-072 URL: http://www.bioone.org/doi/full/10.7589/2013-03-072
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
DOI: 10.7589/2013-03-072
Journal of Wildlife Diseases, 49(4), 2013, pp. 1042–1046 # Wildlife Disease Association 2013
Outbreak of Type C Botulism in Birds and Mammals in the Emilia Romagna Region, Northern Italy Francesco Defilippo,1,4 Andrea Luppi,1 Giulia Maioli,1 Dario Marzi, 2 Maria Cristina Fontana,1 Federica Paoli,3 Paolo Bonilauri,1 Michele Dottori,1 and Giuseppe Merialdi1 1Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna (IZSLER), Brescia, Italy; 2Area dipartimentale, Sanita` Pubblica Veterinaria, AUSL Reggio Emilia, Italy; 3Agenzia Regionale Protezione Ambiente (ARPA), Italy; 4 Corresponding author (email: [email protected])
ABSTRACT: Over a 7-day period beginning 8 August 2011, a large number of wild birds of several species were found dead or with neurologic clinical signs along the shore of Crostolo stream, in the Emilia Romagna region, Italy. Twenty-eight Mallards (Anas platyrhynchos), two Hooded Crows (Corvus corone cornix), and three coypus (Myocastor coypus) were found moribund on the Crostolo stream bank, collected, and sent to Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna, Reggio Emilia Section. The cause of mortality was determined to be Clostridium botulinum type C toxin. The toxin was identified by a mouse bioassay for botulinum toxins and confirmed in bird sera and blowfly larvae (Lucilia caesar) collected from the stomachs of birds. Key words: Maggot mass, toxins, type C botulism, wild birds.
Avian botulism, mainly caused by ingestion of type C toxins produced by Clostridium botulinum, is a common cause of death for waterbirds worldwide (Na-Ri et al., 2010). We describe an outbreak of botulism that occurred in August 2011 along Crostolo stream, which flows through Reggio Emilia (44u679640N, 10u629570E) in the Emilia Romagna region, Italy. In the summer, stream flow rate is usually reduced, and as a consequence, water stagnation is observed. The highest average monthly temperature (27.3 C) and the lowest precipitation (0.00 mm) for 2011 were recorded in August; the biochemical oxygen demand was 6 mg/L, and the chemical oxygen demand was 16 mg/L. The Crostolo stream is populated commonly with waterbirds. In the late summer
of 2008, a botulism outbreak occurred involving a large number of birds. On 8 August 2011, several Mallards (Anas platyrhynchos) were found dead in the Crostolo stream. Over the following days, mortality extended to Hooded Crows (Corvus corone cornix), Little Egrets (Egretta garzetta), Common Moorhens (Gallinula chloropus), Yellow Wagtails (Motacilla flava), and several coypus (Myocastor coypus). The dead animals and the decaying carcasses were collected and destroyed promptly. From the first report of bird mortality on 8 August 2011 until the end of the phenomenon, which lasted 1 wk, 80 dead birds and 16 coypus were collected by the Provincial Veterinary Service along the banks or in the water of the Crostolo stream. Thirty-five live, sick Mallards that showed clinical signs characterized by weakness of legs and wings, inability to sustain flight, and flaccid paralysis were collected. These were sent to a wildlife rehabilitation center and given fluid and antibiotic therapy. Thirty of 35 Mallards sent to the wildlife rehabilitation center recovered completely. Twenty-eight Mallards, two Hooded Crows, and three coypus found moribund on the Crostolo stream bank were collected by the Provincial Veterinary Service and transported to Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna, Laboratory of Reggio Emilia, for diagnostic testing. None of the animals showed specific gross lesions. Maggots (third-stage larvae of Lucilia caesar
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[Szpila, 2009]) were observed in the stomach content of 20 of 28 dead Mallards. The alimentary canal was empty in the remaining birds. During postmortem examination, blood clots were collected from the hearts of all animals and maggots (if any) from their stomachs. Blood clots were centrifuged to obtain serum. Mallard sera were pooled into seven pools of four samples each to obtain sufficient material for the mouse bioassay. Sera from crows and coypus were tested individually. Maggots collected from 20 Mallard stomachs were also pooled into five pools, four samples each. Maggots were carefully washed to remove external contamination, homogenized, and submitted to overnight cold extraction (4 C) in gelatin diluent (0.2% gelatin, 0.4% Na2PO4; pH 6.4, 1:1 [w/v]). Serum samples and maggot extracts were used for mouse bioassays carried out according to Centers for Disease Control and Prevention (1998) using type E and C antitoxins. Samples of intestine, heart, kidney, liver, and brain were collected and tested for viral infectious diseases using different PCR methods: avian influenza (Spackman et al., 2002), Flavivirus genus (Manarolla et al., 2009), Usutu virus (Scaramozzino et al., 2001), and West Nile virus (Tang et al., 2006). Samples of intestine and liver were tested for Salmonella spp. using standardized methods. Liver also was cultured directly on blood agar, serum agar, and Hektoen enteric agar. All pools of sera and maggots were positive by mouse bioassay, showing typical signs of botulism during the first 12 hr after inoculation. Mice were subsequently protected by C. botulinum type C antitoxin. Virologic and bacteriologic tests were negative. The first avian botulism outbreak in Italy, reported in the late summer of 1973 in the Emilia Romagna region, involved Mallards and other ducks. Since its first description, 14 avian botulism outbreaks have been reported in seven Italian regions: Emilia Romagna, Sardinia, Lazio, Tuscany, Piedmont, Veneto, and Liguria
1043
(Table 1 and Fig. 1; Annibali et al., 2011). All of these outbreaks were characterized by the presence of conditions favorable for the growth of C. botulinum. These factors include optimal environmental conditions for spore germination and bacterial growth, suitable material or substrates that provide energy for bacterial replication, and a means of toxin transfer to birds. All of these conditions influenced the occurrence of outbreaks; however, some conditions in places (lakes, streams, and rivers) where outbreaks had occurred were significantly different compared with those of places in which no botulism outbreak occurred (Rocke, 2006). In the outbreak area in the late summer (August/September) environmental conditions were suitable for growth of C. botulinum: shallow water, increase in air and water temperature, increase in the sediment temperature, and decaying organic matter. Temperature plays a critical role in the multiplication of C. botulinum and toxin production. Temperatures at the time of the outbreak were 24.2–27.2 C, satisfying the conditions required for C. botulinum multiplication and toxigenesis (Segner et al., 1971). Additionally, the absence of precipitation in August could have enhanced the deterioration of the aquatic conditions, increasing spore germination, bacterial growth, and toxin production by C. botulinum. The source of the botulinum toxin cannot be identified; however, it is likely that the toxin was released into the food chain because of several contributory factors. Decaying vertebrate carcasses may have played a major role by providing a suitable substrate for growth of C. botulinum and production of type C toxins; decaying carcasses provide a protein-rich and anaerobic environment. The role of migratory birds in the origin of botulism outbreaks is a topic of debate. Birds can act as mechanical carriers of C. botulinum spores and can disperse them to adjacent or distant water reservoirs, where they can germinate and cause avian
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TABLE 1.
Outbreaks of avian Clostridium botulinum type C in wild birds and coypu in Italy, 1973–2011.
Location
Season and Year
Emilia-Romagna
August 1973 (first case in Italy) June 1990
Emilia-Romagna Emilia-Romagna Sardinia Sardinia Lazio Emilia-Romagna
August 1994 July 1999 August 2007 September and October 2008 August 2008
Lazio
August 2009
Liguria Veneto
August 2009 August 2009
Tuscany Sardinia Piedmont
August 2009 September 2010 August 2011
Emilia-Romagna
August 2011
a
Species affected
No. of bird deathsa
Mallard (Anas platyrhynchos)
N/A
Rock Partridge (Alectoris graeca), Pheasant (Phasianus colchicus) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Teal (Anas crecca) Mallard (Anas platyrhynchos), Teal (Anas crecca) Mallard (Anas platyrhynchos), Coot (Fulica atra)
N/A
Common Kingfisher (Alcedo atthis), Great Cormorant (Phalacrocorax carbo), Mallard (Anas platyrhynchos), Yellow Wagtail (Motacilla flava), Hooded Crow (Corvus cornix), coypu (Myocastor coypus) Mallard (Anas platyrhynchos), Little Egret (Egretta garzetta) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), coypu (Myocastor coypus) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Teal (Anas crecca) Little Egret (Egretta garzetta), Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Hooded Crow (Corvus cornix), Yellow Wagtail (Motacilla flava), Little Egret (Egretta garzetta), coypu (Myocastor coypus)
N/A N/A N/A 28 30
18 30 80 9 N/A 4 96
N/A 5 data not available.
botulism (Zdenek, 2004). Some outbreaks of avian botulism have been linked to bird migration routes (Zdenek, 2004). Every year several species of wild birds, in particular the Mallard, migrate from other European countries to Italy. Italy hosts Mallards originating from a wide geographic area: Central Europe (Germany, Austria, Poland, Czech Republic, Switzerland, French Camargue, and southern Germany), northern Europe (Denmark, Sweden, and the UK), and eastern Europe. The movement of migratory birds from these countries to Italy starts at the end of August, increases in November, and reaches a peak from December until March (Spina and Volponi, 2008). Spores of C. botulinum transported mechanically from contaminated areas may trigger outbreaks even
several months after the occurrence of the environmental contamination when the conditions became optimal for spore germination and bacterial growth. The detection of C. botulinum type C toxins in dead larvae collected in the alimentary canal of the carcasses suggests that consumption of toxin-bearing fly larvae was a likely source of intoxication in waterfowl (Shayegani et al., 1984). Fly larvae and other invertebrates are unaffected by the toxin but, as they feed on decaying matter, effectively concentrate the toxin. In this way, botulism outbreaks in waterfowl often become self-perpetuating (Duncan and Jensen, 1976; Wobeser, 1976). For these reasons, the removal of bird carcasses has been suggested as a tool to manage C. botulinum outbreaks (Evelsizer
SHORT COMMUNICATIONS
FIGURE 1. Locations of outbreaks of avian Clostridium botulinum type C in Italy, 1973–2011; number of outbreaks indicated in parentheses.
et al., 2010) since a reduction in density of toxin-laden maggots produced within bird carcasses is assumed to improve the survival rate of healthy birds. Our demonstration of C. botulinum type C intoxication in the strictly vegetarian coypu implicates water and plant contamination by infected carcasses and maggots as a source of the toxin. Further investigations are needed to gain a better understanding of the epidemiologic role of migratory birds, the effect of environmental factors, and the role of invertebrates as vectors of toxins in botulism outbreaks. This study was partially funded by EmiliaRomagna Region, Italy, COMM.07/001. LITERATURE CITED Annibali F, Fiore A, Auricchio B, Fenicia L. 2011. Il botulismo animale: recenti sviluppi di una malattia antica. In: Proceedings of the XIII Congresso Nazionale SIDiLV. Societa` Italiana di Diagnostica di Laboratorio Veterinaria, Trani, Italy, 12–14 October, pp. 138–139.
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Centers for Disease Control and Prevention. 1998. Botulism in the United States, 1899–1996. A handbook for epidemiologists, clinicians and laboratory workers. US Department of Health and Human Service: 15–21. Duncan RM, Jensen WL. 1976. A relationship between avian carcasses and living invertebrates in the epizootiology of avian botulism. J Wildl Dis 12:116–126. Evelsizer DD, Bollinger TK, Dufour KW, Clark RG. 2010. Survival of radio-marked Mallards in relation to management of avian botulism. J Wildl Dis 46:864–877. Manarolla G, Bakonyi T, Gallazzi D, Crosta L, Weissenbo¨ck H, Dorrestein GM, Nowotny N. 2009. Usutu virus in wild birds in northern Italy. Vet Microbiol 141:159–163. Na-Ri S, Seong HB, Jeong HC, Jeong HS, Yun JK, Jeong-Hee K, Gi-Eun R, Hyen MC, In-Pil M, Cheon KY. 2010. An outbreak of type C botulism in waterbirds: Incheon, Korea. J Wildl Dis 46:912–917. Rocke T. 2006. The global importance of avian botulism. In: Waterbirds around the world, Boere G, Galbraith C and Stroud D (eds.). The Stationery Office, Edinburgh, UK, pp. 422– 426. Scaramozzino N, Crance JM, Jouan A, Debriel DA, Stoll F, Garin D. 2001. Comparison of Flavivirus universal primer pairs and development of a rapid, highly sensitive heminested reverse transcription-PCR assay for detection of flaviviruses targeted to a conserved region of the NS5 gene sequences. J Clin Microbiol 39:1922– 1927. Segner WP, Hniidt CFS, Boltz JC. 1971. Minimal growth temperature, sodium chloride tolerance, pH sensitivity, and toxin production of marine and terrestrial strains of Clostridium botulinum type C. Appl Microbiol 22:1025–1029. Shayegani M, Stone WB, Hannett GE. 1984. An outbreak of botulism in waterfowl and fly larvae in New York State. J Wildl Dis 20:86–89. Spackman E, Senne DA, Myers TJ, Bulaga LL, Garber LP, Lohman K, Daum LT, Suarez DL. 2002. Development of a real-time reverse transcriptase PCR assay for type a influenza virus and the avian H5 and H7 hemagglutinin subtypes. J Clin Microbiol 40:3256–3260. Spina F, Volponi S. 2008. Atlante della Migrazione degli Uccelli in Italia. Ministero dell’Ambiente e della Tutela del Territorio e del Mare, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA) 1:190–198. Szpila K. 2009. Key for the identification of third instars of European blowflies (Diptera: Calliphoridae) of forensic importance. In: Current concepts in forensic entomology, Amendt J, Goff ML, Campobasso CP and Grassberger M (eds.). Springer, New York, New York, pp. 43–56.
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Tang Y, Hapip CA, Liu B, Fang CT. 2006. Highly sensitive TaqMan RT-PCR assay for detection and quantification of both lineages of West Nile virus RNA. J Clin Virol 36:177–182. Wobeser G. 1976. Avian botulism—another perspective. J Wildl Dis 33:181–186.
Zdenek H. 2004. An annoted checklist of pathogenic microorganisms associated with migratory birds. J Wildl Dis 40:639–659. Submitted for publication 9 March 2013. Accepted 21 May 2013.
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
DOI: 10.7589/2013-03-072
Journal of Wildlife Diseases, 49(4), 2013, pp. 1042–1046 # Wildlife Disease Association 2013
Outbreak of Type C Botulism in Birds and Mammals in the Emilia Romagna Region, Northern Italy Francesco Defilippo,1,4 Andrea Luppi,1 Giulia Maioli,1 Dario Marzi, 2 Maria Cristina Fontana,1 Federica Paoli,3 Paolo Bonilauri,1 Michele Dottori,1 and Giuseppe Merialdi1 1Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna (IZSLER), Brescia, Italy; 2Area dipartimentale, Sanita` Pubblica Veterinaria, AUSL Reggio Emilia, Italy; 3Agenzia Regionale Protezione Ambiente (ARPA), Italy; 4 Corresponding author (email: [email protected])
ABSTRACT: Over a 7-day period beginning 8 August 2011, a large number of wild birds of several species were found dead or with neurologic clinical signs along the shore of Crostolo stream, in the Emilia Romagna region, Italy. Twenty-eight Mallards (Anas platyrhynchos), two Hooded Crows (Corvus corone cornix), and three coypus (Myocastor coypus) were found moribund on the Crostolo stream bank, collected, and sent to Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna, Reggio Emilia Section. The cause of mortality was determined to be Clostridium botulinum type C toxin. The toxin was identified by a mouse bioassay for botulinum toxins and confirmed in bird sera and blowfly larvae (Lucilia caesar) collected from the stomachs of birds. Key words: Maggot mass, toxins, type C botulism, wild birds.
Avian botulism, mainly caused by ingestion of type C toxins produced by Clostridium botulinum, is a common cause of death for waterbirds worldwide (Na-Ri et al., 2010). We describe an outbreak of botulism that occurred in August 2011 along Crostolo stream, which flows through Reggio Emilia (44u679640N, 10u629570E) in the Emilia Romagna region, Italy. In the summer, stream flow rate is usually reduced, and as a consequence, water stagnation is observed. The highest average monthly temperature (27.3 C) and the lowest precipitation (0.00 mm) for 2011 were recorded in August; the biochemical oxygen demand was 6 mg/L, and the chemical oxygen demand was 16 mg/L. The Crostolo stream is populated commonly with waterbirds. In the late summer
of 2008, a botulism outbreak occurred involving a large number of birds. On 8 August 2011, several Mallards (Anas platyrhynchos) were found dead in the Crostolo stream. Over the following days, mortality extended to Hooded Crows (Corvus corone cornix), Little Egrets (Egretta garzetta), Common Moorhens (Gallinula chloropus), Yellow Wagtails (Motacilla flava), and several coypus (Myocastor coypus). The dead animals and the decaying carcasses were collected and destroyed promptly. From the first report of bird mortality on 8 August 2011 until the end of the phenomenon, which lasted 1 wk, 80 dead birds and 16 coypus were collected by the Provincial Veterinary Service along the banks or in the water of the Crostolo stream. Thirty-five live, sick Mallards that showed clinical signs characterized by weakness of legs and wings, inability to sustain flight, and flaccid paralysis were collected. These were sent to a wildlife rehabilitation center and given fluid and antibiotic therapy. Thirty of 35 Mallards sent to the wildlife rehabilitation center recovered completely. Twenty-eight Mallards, two Hooded Crows, and three coypus found moribund on the Crostolo stream bank were collected by the Provincial Veterinary Service and transported to Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna, Laboratory of Reggio Emilia, for diagnostic testing. None of the animals showed specific gross lesions. Maggots (third-stage larvae of Lucilia caesar
1042
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[Szpila, 2009]) were observed in the stomach content of 20 of 28 dead Mallards. The alimentary canal was empty in the remaining birds. During postmortem examination, blood clots were collected from the hearts of all animals and maggots (if any) from their stomachs. Blood clots were centrifuged to obtain serum. Mallard sera were pooled into seven pools of four samples each to obtain sufficient material for the mouse bioassay. Sera from crows and coypus were tested individually. Maggots collected from 20 Mallard stomachs were also pooled into five pools, four samples each. Maggots were carefully washed to remove external contamination, homogenized, and submitted to overnight cold extraction (4 C) in gelatin diluent (0.2% gelatin, 0.4% Na2PO4; pH 6.4, 1:1 [w/v]). Serum samples and maggot extracts were used for mouse bioassays carried out according to Centers for Disease Control and Prevention (1998) using type E and C antitoxins. Samples of intestine, heart, kidney, liver, and brain were collected and tested for viral infectious diseases using different PCR methods: avian influenza (Spackman et al., 2002), Flavivirus genus (Manarolla et al., 2009), Usutu virus (Scaramozzino et al., 2001), and West Nile virus (Tang et al., 2006). Samples of intestine and liver were tested for Salmonella spp. using standardized methods. Liver also was cultured directly on blood agar, serum agar, and Hektoen enteric agar. All pools of sera and maggots were positive by mouse bioassay, showing typical signs of botulism during the first 12 hr after inoculation. Mice were subsequently protected by C. botulinum type C antitoxin. Virologic and bacteriologic tests were negative. The first avian botulism outbreak in Italy, reported in the late summer of 1973 in the Emilia Romagna region, involved Mallards and other ducks. Since its first description, 14 avian botulism outbreaks have been reported in seven Italian regions: Emilia Romagna, Sardinia, Lazio, Tuscany, Piedmont, Veneto, and Liguria
1043
(Table 1 and Fig. 1; Annibali et al., 2011). All of these outbreaks were characterized by the presence of conditions favorable for the growth of C. botulinum. These factors include optimal environmental conditions for spore germination and bacterial growth, suitable material or substrates that provide energy for bacterial replication, and a means of toxin transfer to birds. All of these conditions influenced the occurrence of outbreaks; however, some conditions in places (lakes, streams, and rivers) where outbreaks had occurred were significantly different compared with those of places in which no botulism outbreak occurred (Rocke, 2006). In the outbreak area in the late summer (August/September) environmental conditions were suitable for growth of C. botulinum: shallow water, increase in air and water temperature, increase in the sediment temperature, and decaying organic matter. Temperature plays a critical role in the multiplication of C. botulinum and toxin production. Temperatures at the time of the outbreak were 24.2–27.2 C, satisfying the conditions required for C. botulinum multiplication and toxigenesis (Segner et al., 1971). Additionally, the absence of precipitation in August could have enhanced the deterioration of the aquatic conditions, increasing spore germination, bacterial growth, and toxin production by C. botulinum. The source of the botulinum toxin cannot be identified; however, it is likely that the toxin was released into the food chain because of several contributory factors. Decaying vertebrate carcasses may have played a major role by providing a suitable substrate for growth of C. botulinum and production of type C toxins; decaying carcasses provide a protein-rich and anaerobic environment. The role of migratory birds in the origin of botulism outbreaks is a topic of debate. Birds can act as mechanical carriers of C. botulinum spores and can disperse them to adjacent or distant water reservoirs, where they can germinate and cause avian
1044
JOURNAL OF WILDLIFE DISEASES, VOL. 49, NO. 4, OCTOBER 2013
TABLE 1.
Outbreaks of avian Clostridium botulinum type C in wild birds and coypu in Italy, 1973–2011.
Location
Season and Year
Emilia-Romagna
August 1973 (first case in Italy) June 1990
Emilia-Romagna Emilia-Romagna Sardinia Sardinia Lazio Emilia-Romagna
August 1994 July 1999 August 2007 September and October 2008 August 2008
Lazio
August 2009
Liguria Veneto
August 2009 August 2009
Tuscany Sardinia Piedmont
August 2009 September 2010 August 2011
Emilia-Romagna
August 2011
a
Species affected
No. of bird deathsa
Mallard (Anas platyrhynchos)
N/A
Rock Partridge (Alectoris graeca), Pheasant (Phasianus colchicus) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Teal (Anas crecca) Mallard (Anas platyrhynchos), Teal (Anas crecca) Mallard (Anas platyrhynchos), Coot (Fulica atra)
N/A
Common Kingfisher (Alcedo atthis), Great Cormorant (Phalacrocorax carbo), Mallard (Anas platyrhynchos), Yellow Wagtail (Motacilla flava), Hooded Crow (Corvus cornix), coypu (Myocastor coypus) Mallard (Anas platyrhynchos), Little Egret (Egretta garzetta) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), coypu (Myocastor coypus) Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Teal (Anas crecca) Little Egret (Egretta garzetta), Mallard (Anas platyrhynchos) Mallard (Anas platyrhynchos), Hooded Crow (Corvus cornix), Yellow Wagtail (Motacilla flava), Little Egret (Egretta garzetta), coypu (Myocastor coypus)
N/A N/A N/A 28 30
18 30 80 9 N/A 4 96
N/A 5 data not available.
botulism (Zdenek, 2004). Some outbreaks of avian botulism have been linked to bird migration routes (Zdenek, 2004). Every year several species of wild birds, in particular the Mallard, migrate from other European countries to Italy. Italy hosts Mallards originating from a wide geographic area: Central Europe (Germany, Austria, Poland, Czech Republic, Switzerland, French Camargue, and southern Germany), northern Europe (Denmark, Sweden, and the UK), and eastern Europe. The movement of migratory birds from these countries to Italy starts at the end of August, increases in November, and reaches a peak from December until March (Spina and Volponi, 2008). Spores of C. botulinum transported mechanically from contaminated areas may trigger outbreaks even
several months after the occurrence of the environmental contamination when the conditions became optimal for spore germination and bacterial growth. The detection of C. botulinum type C toxins in dead larvae collected in the alimentary canal of the carcasses suggests that consumption of toxin-bearing fly larvae was a likely source of intoxication in waterfowl (Shayegani et al., 1984). Fly larvae and other invertebrates are unaffected by the toxin but, as they feed on decaying matter, effectively concentrate the toxin. In this way, botulism outbreaks in waterfowl often become self-perpetuating (Duncan and Jensen, 1976; Wobeser, 1976). For these reasons, the removal of bird carcasses has been suggested as a tool to manage C. botulinum outbreaks (Evelsizer
SHORT COMMUNICATIONS
FIGURE 1. Locations of outbreaks of avian Clostridium botulinum type C in Italy, 1973–2011; number of outbreaks indicated in parentheses.
et al., 2010) since a reduction in density of toxin-laden maggots produced within bird carcasses is assumed to improve the survival rate of healthy birds. Our demonstration of C. botulinum type C intoxication in the strictly vegetarian coypu implicates water and plant contamination by infected carcasses and maggots as a source of the toxin. Further investigations are needed to gain a better understanding of the epidemiologic role of migratory birds, the effect of environmental factors, and the role of invertebrates as vectors of toxins in botulism outbreaks. This study was partially funded by EmiliaRomagna Region, Italy, COMM.07/001. LITERATURE CITED Annibali F, Fiore A, Auricchio B, Fenicia L. 2011. Il botulismo animale: recenti sviluppi di una malattia antica. In: Proceedings of the XIII Congresso Nazionale SIDiLV. Societa` Italiana di Diagnostica di Laboratorio Veterinaria, Trani, Italy, 12–14 October, pp. 138–139.
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