Botulism among penned pheasants and protection by vaccination with CI toxoid

Botulism in Cattle: A Case Report of an Outbreak in Sardinia (Italy)

Clostridium botulinum is the main causative agent of botulism in humans and animals. The ingestion of the botulinum neurotoxin, usually types C and D, has been shown to produce disease (neurological symptoms) in most botulism cases in cattle. We report an outbreak in Southern Sardinia that involved a livestock farm with 120 animals, 39 of which died. The aim of this report is to describe the course of this outbreak and the progression of symptoms up to the death of some animals; we also describe the therapeutic approach applied in this case and the analytical techniques used to diagnose the disease. Finally, we emphasize the importance of promptly proceeding with the sampling of several matrixes when a suspicion of botulism arises.

Botulism in Wild Birds and Changes in Environmental Habitat: A Relationship to be Considered

Simple summary

Human activities, even those aimed at improving a natural area, can interfere with wildlife and their environment, potentially leading to some changes. In this paper, a botulism outbreak which occurred in waterfowls in a nature reserve after a conservative action is reported. In particular, an artificial pond was created in order to improve the environment of waterfowls, but gray mullets (Mugil cephalus) settled in the pond and proliferated. Fish mortality was observed during summer, leading to an accumulation of decaying organic material, thus creating the optimal conditions for Clostridium botulin growth and toxin production. In the same period, the botulism outbreak with flaccid paralysis and sudden mortality rapidly occurred in waterfowls. The toxin mosaic type C/D was identified as responsible for the disease outbreak. The outbreak rapidly resolved after the removal of the fish carcasses, highlighting the importance of a correct management for any action in natural contexts. In conclusion, before considering any activity in wildlife habitats, it is important to assess first its possible impact on wildlife.

Abstract

Any human activity, even if aimed at the improvement of a natural area, can potentially affect wildlife, leading to possible short-term or long-term changes due to the human–wildlife interaction. In this study, a botulism outbreak which occurred in waterfowl in a nature reserve after a conservative environmental action is reported. More than 180 different species of wild birds, including seventy waterfowl species, live in the area. The wildlife reserve rangers built an artificial pond equipped with draining canals in the wetland in order to improve the environment of waterfowl species and to facilitate their supply of food. Then, presumably due to tidal rides, gray mullets (Mugil cephalus) arrived from the sea and settled in the pond. The number of fishes gradually increased, and several fishes died with a peak of mortality in the summer of 2017, creating a great amount of decaying organic material and the optimal conditions for Clostridium botulinum growth and toxin production. A botulism outbreak then occurred rapidly and was characterised by flaccid paralysis and sudden mortality of the birds. Seven mallard ducks (Anas platyrhynchos), 4 common teals (Anas crecca), 1 garganey (Anas querquedula), 2 wood sandpipers (Tringa glareola), 1 little egret (Egretta garzetta), 1 little grebe (Tachybaptus ruficollis), and 4 Eurasian coots (Fulica atra) were found dead. Interestingly, the toxin identified as responsible for the disease outbreak was the mosaic of type C and D toxins (C/D type). The prompt removal of the fish carcasses led to a rapid resolution of the outbreak of the disease, highlighting the relevance of a correct management for any action in environmental contexts. The conclusion is that any human activity in wildlife habitats should be carefully considered in order to assess the possible impacts and to quickly identify the possible risks of changes in wildlife population.

Identification and characterization of Clostridium botulinum group III field strains by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS)

Animal botulism is primarily due to botulinum neurotoxin (BoNT) types C, D or their chimeric variants C/D or D/C, produced by Clostridium botulinum group III, which appears to include the genetically indistinguishable Clostridium haemolyticum and Clostridium novyi. In the present study, we used matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI TOF MS) to identify and characterize 81 BoNT-producing Clostridia isolated in 47 episodes of animal botulism. The instrument's default database, containing no entries for Clostridium botulinum, permitted reliable identification of 26 strains at the genus level. Although supplementation of the database with reference strains enhanced the instrument's ability to identify the neurotoxic strains at the genus level, resolution was not sufficient to recognize field strains at species level. Characterization by MALDI TOF confirmed the well-documented phenotypic and genetic differences between Clostridium botulinum strains of serotypes normally implicated in human botulism (A, B, E, F) and other Clostridium species able to produce BoNTs type C and D. The chimeric and non-chimeric field strains grouped separately. In particular, very low similarity was found between two non-chimeric type C field strains isolated in the same outbreak and the other field strains. This difference was comparable with the differences among the various Clostridia species included in the study. Characterization by MALDI TOF confirmed that BoNT-producing Clostridia isolated from animals are closely related and indistinguishable at the species level from Clostridium haemolyticum and Clostridium novyi reference strains. On the contrary, there seem to be substantial differences among chimeric and some non-chimeric type C strains.

Evidence for a natural humoral response in dairy cattle affected by persistent botulism sustained by non-chimeric type C strains

Bovine botulism is a sporadic acute disease that usually causes catastrophic losses in the herds. The unusual clinical evolution of a persistent mild outbreak in a dairy herd, prompted us to characterize the neurotoxin gene profile of the strain involved and to evaluate whether seroconversion had occurred. Diagnosis was based on mild classical symptoms and was supported by PCR and bacteriological findings, which revealed the involvement of a non-mosaic type C strain. An in-house ELISA was developed to detect antibodies to botulinum neurotoxin type C and its performance was evaluated in a vaccination study. Fifty days after the index case, fecal and serum samples were collected from the 14 animals of the herd and screened for Clostridium botulinum and anti-botulinum neurotoxin antibodies type C, respectively. The in-house developed ELISA was also used to test 100 sera samples randomly collected from 20 herds. Strong ELISA reactions were observed in 3 convalescent and 5 asymptomatic animals involved in the studied outbreak. The ELISA-positive cows all tested positive for non-mosaic C. botulinum type C in the feces and the same strain was also detected in the alfalfa hay, suspected to be the carrier source. Ten out of the 100 randomly collected sera tested positive for anti-botulinum neurotoxin type C antibodies: 7 had borderline values and 3 from the same herd showed titers three times higher than the cut-off. We concluded that type C botulism in cattle may occur with variable severity and that prolonged exposure to sublethal doses of botulinum neurotoxin C may occur, resulting in detectable antibodies.

Protective effect of botulinum C/D mosaic toxoid against avian botulism

Avian botulism is a paralytic disease caused by a toxin produced by Clostridium botulinum type C. Since type C isolates from cases of avian botulism produced a neurotoxin consisting of a mosaic form of parts of type C and D neurotoxins, we examined the antitoxin titers in the convalescent sera of botulism-affected birds which belonged to family Anatidae. ELISA using the C/D mosaic neurotoxin as an antigen revealed that the antibody was detected in the sera at 2 weeks, but not at 5 weeks after the onset, suggesting that the antibody only appeared for a short period in the convalescent phase. However, we failed to detect the antibody titers with anti-chicken IgG instead of anti-duck IgG. We therefore examine the immunological properties of IgG among different families and species. The results revealed that different species of IgG in the same family exhibited strong cross-reactivity. Ducks immunized once with the toxoid together with a commercial oil-adjuvanted vaccine were found to develop sufficient antibody to protect against a challenge with a lethal toxin dose. The ELISA titers did not correspond to the neutralization titers in the sera of immunized ducks at the early stage during immunization. These findings suggest that the neutralizing titer was more useful than the ELISA titer for evaluating the protection against the toxin, but the ELISA technique may be applicable for detecting the occurrence of botulism.

Occurrence and distribution of Vibrio spp., Listonella spp., and Clostridium botulinum in the Seto Inland Sea of Japan

The distribution of Vibrio species in samples of surface water, bottom water (water 2 m above the sediment), and sediment from the Seto Inland Sea was studied. A simple technique using a membrane filter and short preenrichment in alkaline peptone water was developed to resuscitate the injured cells, followed by plating them onto TCBS agar. In addition, a survey was conducted to determine the incidence of Clostridium botulinum in sediment samples. Large populations of heterotrophs were found in surface water, whereas large numbers of total vibrios were found in bottom water. In samples from various water sampling regions, high counts of all bacterial populations were found in the inner regions having little exchange of seawater when compared with those of the open region of the inland sea. In the identification of 463 isolates, 23 Vibrio spp. and 2 Listonella spp. were observed. V. harveyi was prevalent among the members of the Vibrio genus. Vibrio species were categorized into six groups; an estimated 20% of these species were in the so-called "pathogenic to humans" group. In addition, a significant proportion of this group was hemolytic and found in the Bisan Seto region. V. vulnificus, V. fluvialis, and V. cholerae non-O1 predominated in the constricted area of the inland sea, which is eutrophic as a result of riverine influence. It was concluded that salinity indirectly governs the distribution of total vibrios and analysis of variance revealed that all bacterial populations were distributed homogeneously and the variance values were found to be significant in some water sampling regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid method for purification of Clostridium botulinuh type C neurotoxin by High Performance Liquid Chromatography (HPLC )

The culture supernatant of Clostridium botulinum type C, concentrated by addition of RNA, acid precipitation and subsequent protamine treatment was used as starting material for rapid purification of L toxin (mol. wt. ca. 500K) and M toxin (mol. wt. ca. 350K) of C1 neurotoxin by ion-exchange chromatography on a Mono S column by fast performance liquid chromatography (FPLC). L and M toxins were highly purified further by gel permeation chromatography through a TSK G3000SW column at pH 6.0 by high performance liquid chromatography (HPLC). Purified S toxin (mol. wt. ca. 150K, Cl neurotoxin without a nontoxic component) was then obtained from L toxin rapidly by gel permeation chromatography at pH 7.3 through a TSK G3000SW column by HPLC. Purified S toxin was also obtained rapidly from M and L toxins by ion-exchange chromatography on a Mono Q column at pH 8.0 using an FPLC system. The purified preparations of L, M and S toxins gave single bands on conventional polyacrylamide gel electrophoresis, and had specific activities of 2.8, 6.7, and 14-21 × 10⁷ LD₅₀/mg N, respectively, in mice. On immunoelectrophoresis, purified S toxin gave a single arc against anti-crude toxin serum. The yield of toxicity as L and M toxins was 73.1% (32.5% as L toxin and 40.6% as M toxin) from the protamine-treated concentrated culture supernatant. The recovery of toxicity as S toxin from purified L or M toxin was almost 100% (97.6-100% of L toxin and 97.5% of M toxin). These procedures provide a rapid method for purifying L and M toxins, which have stable toxicities. The method will also be very useful for rapid preparation of the toxic component (S toxin) of C1 neurotoxin, which is unstable, in small amounts from the L and M toxins just before its use in experiments.