Asymptomatic Carriage of C. botulinum Type D/C in Broiler Flocks as the Source of Contamination of a Massive Botulism Outbreak on a Dairy Cattle Farm

Abstract

In winter 2018, a massive type D/C cattle botulism outbreak occurred on a mixed dairy and broiler farm in France. An investigation was conducted based on the hypothesis of asymptomatic carriage in poultry. We set out to identify the source of contamination of the dairy cattle and to monitor the contamination of broilers over time, including the hatchery delivering chicks to the farm. Environmental samples were collected on the farm during the cattle outbreak (n = 40), after the outbreak for three successive broiler flocks (n = 128), and once in the hatchery delivering the chicks (n = 58). These samples were analyzed using real-time PCR after an enrichment step to detect Clostridium botulinum type D/C. The results showed contamination in the manure from the broilers raised just before the onset of the cattle outbreak (5 + /5), as well as in some of the components of the cattle ration (3 + /17). This latter contamination is likely due to the use of the same tractor bucket to remove litter from the poultry house and to prepare the cattle ration on the same day. Contamination monitoring over several months revealed continuous asymptomatic carriage in the broilers (4 + /20 and 17 + /20 cloacal swabs in 2 successive flocks), a persistence of C. botulinum type D/C in the ventilation system of the poultry house (8 + /14), and contamination of the equipment coming from the hatchery used for delivering the chicks (3 + /18). Further investigations conducted in the hatchery demonstrated contamination in the hatchery by C. botulinum type D/C (6 + /58). Comparison of samples using a multilocus variable number tandem repeat analysis showed the same profile for samples collected on broilers, cattle and in the hatchery. This study highlighted the crucial role of the implementation of biosecurity measures in mixed farms to avoid cross-contamination between production units given the potential asymptomatic carriage of poultry. This study also revealed the contamination of the poultry hatchery. Further investigations are required to better understand the role of hatcheries in the epidemiology of animal botulism.

Clostridium botulinum type C, D, C/D, and D/C: An update

“…One is the presence of animal carcasses (domestic or wild) that provide a substrate for the development of C. botulinum and production of BoNT (Le Maréchal et al, 2019). The second one is poultry manure, as poultry can be asymptomatic carriers of C. botulinum (Souillard et al, 2017(Souillard et al, , 2021. Contamination of feed or water by these two sources can occur directly with the presence of the dead animals or manure in the drinking water or in the feed.…”

“…Contamination of feed or water by these two sources can occur directly with the presence of the dead animals or manure in the drinking water or in the feed. Contamination can also occur indirectly via contaminated equipment (e.g., tractor bucket), clothing [farmer, technician, veterinarian (Souillard et al, 2017(Souillard et al, , 2021], or by airborne route (Hogg et al, 2008). Soil and feces, through intestinal carriage by animals, not only livestock but also other domestic or wild animals, can also be a source of contamination (Figure 2).…”

“…Contaminated poultry manure appears therefore to be the main vehicle of contamination of C. botulinum, with a direct or indirect link between the cattle farm and a poultry flock. The source of manure contamination is asymptomatic poultry carrying C. botulinum, and excreting it into the litter (Souillard et al, 2017(Souillard et al, , 2021. Contamination of water or feed by a dead animal is also a major source of contamination for outbreaks of bovine botulism (Galey et al, 2000;Le Maréchal et al, 2019).…”

Prevalent toxin types of Clostridium botulinum in South Korean cattle farms

“…Formidable outbreaks of type D cattle botulism have occurred in beef cattle fed chicken litter in Australia and Israel ( Egyed, 1987 ). However, diverse types of toxin, such as types A, C/D, and D/C, have been reported in related samples during outbreaks in cattle ( Frye et al, 2020 ; Hartley et al, 2009 ; Otaka et al, 2020 ; Souillard et al, 2021 ).…”

A Four-Monoclonal Antibody Combination Potently Neutralizes Multiple Botulinum Neurotoxin Serotypes C and D

“…Type C typically occurs in mammals such as dogs [ 11 , 12 , 13 ], mink [ 14 ], horses [ 15 , 16 ], and cattle [ 17 ]. BoNT/D and mosaic-type BoNT/DC botulism outbreaks are rare and are usually associated with horses [ 18 ] and cattle [ 19 , 20 , 21 ]. In cattle, outbreaks have high fatality rates [ 22 , 23 ].…”