First record of mass wild waterfowl mortality due to Clostridium botulinum in Brazilian semiarid

Abstract

In 2008, 270 wild birds from aquatic environments were found dead or debilitated on the banks of smaller lakes that had been formed due to the decrease in the level of the holding lake of the Sobradinho Dam located on the São Francisco River in the Caatinga of Bahia, Brazil. The outbreak occurred months after the dam's partial drainage, with the formation of puddles that accumulated decomposing organic material. Amongst the 270 individuals examined and/or found dead, the majority (50%) of the birds found belonged to the Anatidae family. The debilitated birds presented neurological clinical signs including lack of motor coordination, weakness, grave flaccid paralysis in the legs, wings, neck and eyelids, diarrhea, and dyspnea. Tissue samples of the birds were collected, as were water samples and samples of the substrate of the lakes. Zoonotic arboviroses or heavy metals were not detected. Analyses of liver and digestive tract content samples through bioassay and serum neutralization in mice revealed the presence of type C botulinic toxin in the viscerae samples, and type D in sediment samples. According to our knowledge, this is the first record of an outbreak of botulism in wild birds in natural conditions in Brazil.

Type C botulism outbreak in free-ranging waterfowl in Goiás

“…Conditions considered favorable for botulism outbreaks in waterfowl include large amounts of protein-rich organic matter, little available oxygen, high temperatures, and shallow water. The drainage of natural and artificial aquatic environments can favor the multiplication of Clostridium botulinum and the occurrence of outbreaks, as it predisposes the accumulation of organic matter and decreased oxygen availability (Lima et al 2020). Botulism outbreaks usually occur during the warmest months of the year and October is considered the warmest month of the year in the city of Quirinópolis, Goiás, which coincides with the time of the outbreak (Weather Spark 2022).…”

“…In the present study, botulinum toxin was detected in the water of the lake where the birds lived and fed. Lima et al (2020) reported an outbreak of type C botulism in wild and migratory waterfowl at the Sobradinho Dam. At that time, the level of the dam was low, which caused the Pesq.…”

“…To date, eight different botulinum neurotoxin serotypes with similar pharmacological actions have been identified and classified in A, B (Burke 1919), C (Bengston 1922), D (Gunnison & Meyer 1929), E (Gunnison et al 1936), F (Moller & Scheibel 1960), G (Gimenez & Ciccareli 1970) and H (Barash & Arnon 2014). Regarding birds, serotypes C and C/D are the most reported in outbreaks, although types E and A can also be associated with botulism outbreaks in birds (Linares et al 1994, Neimanis et al 2007, Chipault et al 2015, Badagliacca et al 2018, Lima et al 2020, Rosciano et al 2021, Rogers et al 2021, Quevedo et al 2022.…”