Outbreak of botulism type B in a dairy cattle herd: clinical and epidemiological aspects

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

Clostridium botulinum is the main causative agent of botulism, a neurological disease encountered in humans as well as animals. Nine types of botulinum neurotoxins (BoNTs) have been described so far. Amongst these "toxinotypes," the A, the B and E are the most frequently encountered in humans while the C, D, C/D and D/C are mostly affecting domestic and wild birds as well as cattle. In France for instance, many cases and outbreaks are reported in these animal species every year. However, underestimation is very likely at least for avifauna species where the detection of dead animals can be challenging. Knowledge about BoNTs C, D, C/D, and D/C and the diseases they cause in animals and humans is still scarce and unclear. Specifically, the potential role of animal botulism outbreaks in cattle and poultry as a source of human illness needs to be further assessed. In this narrative review, we present the current knowledge about toxinotypes C, D, C/D, and D/C in cattle and poultry with, amongst various other aspects, their epidemiological cycles. We also discuss the zoonotic potential of these toxinotypes and some possible ways of risk mitigation. An adapted and effective management of botulism outbreaks in livestock also requires a better understanding of these less common and known toxinotypes.

Human and animal botulism surveillance in France from 2008 to 2019

Botulism is a human and animal neurological disease caused by the action of bacterial neurotoxins (botulinum toxins) produced by bacteria from the genus Clostridium. This disease induces flaccid paralysis that can result in respiratory paralysis and heart failure. Due to its serious potential impact on public health, botulism is a closely monitored notifiable disease in France through a case-based passive surveillance system. In humans, this disease is rare, with an average of 10 outbreaks reported each year, mainly due to the consumption of contaminated foods. Type B and to a lesser extend type A are responsible for the majority of cases of foodborne botulism. Each year, an average of 30 outbreaks are recorded on poultry farms, about 20 cases in wild birds and about 10 outbreaks in cattle, involving a large number of animals. Mosaic forms C/D and D/C in birds and cattle, respectively, are the predominant types in animals in France. Types C and D have also been observed to a lesser extent in animals. With the exception of botulinum toxin E, which was exceptionally detected throughout the period in wild birds, the types of botulism found in animal outbreaks are different from those identified in human outbreaks over the last ten years in France and no human botulism outbreaks investigated have been linked to animal botulism. In line with the One Health concept, we present the first integrative approach to the routine surveillance of botulism in humans and animals in France.

Public Health Risk Associated with Botulism as Foodborne Zoonoses

Botulism is a rare but severe neurological disease in man and animals that is caused by botulinum neurotoxins (BoNTs) produced by Clostridium botulinum and atypical strains from other Clostridium and non-Clostridium species. BoNTs are divided into more than seven toxinotypes based on neutralization with specific corresponding antisera, and each toxinotype is subdivided into subtypes according to amino acid sequence variations. Animal species show variable sensitivity to the different BoNT toxinotypes. Thereby, naturally acquired animal botulism is mainly due to BoNT/C, D and the mosaic variants CD and DC, BoNT/CD being more prevalent in birds and BoNT/DC in cattle, whereas human botulism is more frequently in the types A, B and E, and to a lower extent, F. Botulism is not a contagious disease, since there is no direct transmission from diseased animals or man to a healthy subject. Botulism occurs via the environment, notably from food contaminated with C. botulinum spores and preserved in conditions favorable for C. botulinum growth and toxin production. The high prevalence of botulism types C, D and variants DC and CD in farmed and wild birds, and to a lower extent in cattle, raises the risk of transmission to human beings. However, human botulism is much rarer than animal botulism, and botulism types C and D are exceptional in humans. Only 15 cases or suspected cases of botulism type C and one outbreak of botulism type D have been reported in humans to date. In contrast, animal healthy carriers of C. botulinum group II, such as C. botulinum type E in fish of the northern hemisphere, and C. botulinum B4 in pigs, represent a more prevalent risk of botulism transmission to human subjects. Less common botulism types in animals but at risk of transmission to humans, can sporadically be observed, such as botulism type E in farmed chickens in France (1998-2002), botulism type B in cattle in The Netherlands (1977-1979), botulism types A and B in horses, or botulism type A in dairy cows (Egypt, 1976). In most cases, human and animal botulisms have distinct origins, and cross transmissions between animals and human beings are rather rare, accidental events. But, due to the severity of this disease, human and animal botulism requires a careful surveillance.

The new Israeli feed safety law: challenges in relation to animal and public health

The Israeli feed safety legislation, which came to prominence in the early 1970s, has undergone a major change from simple feed safety and quality regulations to a more holistic concept of control of feed safety and quality throughout the whole feed production chain, from farm to the end user table. In February 2014, a new law was approved by the Israeli parliament, namely the Control of Animal Feed Law, which is expected to enter into effect in 2017. The law is intended to regulate the production and marketing of animal feed, guaranteeing the safety and quality of animal products throughout the production chain. The responsibility on the implementation of the new feed law was moved from the Plant Protection Inspection Service to the Veterinary Services and Animal Health. In preparation for the law's implementation, we have characterized the various sources and production lines of feed for farm and domestic animals in Israel and assessed the current feed safety challenges in terms of potential hazards or undesirable substances. Moreover, the basic requirements for feed safety laboratories, which are mandatory for analyzing and testing for potential contaminants, are summarized for each of the contaminants discussed. © 2016 Society of Chemical Industry.

Short communication: Attempts to identify Clostridium botulinum toxin in milk from three experimentally intoxicated Holstein cows

Three adult lactating Holstein cows were injected in the subcutaneous abdominal vein with 175 ng/kg of body weight of Clostridium botulinum type C toxin (451 cow median toxic doses) to determine if this botulinum toxin crosses the blood-milk barrier. Whole blood (in sodium heparin) and clotted blood serum samples were taken at 0 min, 10 min, and 3, 6, 9, and 12 h postinoculation. Milk samples were taken at 0 min and at 3, 6, 9 and 12 h postinoculation. All samples were tested for the presence of the toxin using the mouse bioassay and immunostick ELISA test. The immunostick ELISA identified the toxin in whole blood and the mouse bioassay identified the toxin in serum at all times examined in all 3 animals. Toxin was not identified by either detection method in milk samples collected from the 3 animals. From these results, it appears that Clostridium botulinum type C toxin does not cross from the blood to the milk in detectable concentrations.

Cattle immune response to botulinum type D toxoid: Results of a vaccination study

Cattle botulism is a food-borne intoxication caused by the ingestion of preformed botulinum neurotoxins (BoNT) of serotypes B, C, or D. Protection in cattle against botulinum intoxication is based on the presence of specific serum neutralizing antibodies upon exposure. Outbreaks in vaccinated cattle have raised concerns about vaccine quality and efficacy. To this end, three different immunization protocols and the effect of maternal anti-BoNT/D antibodies, at the priming dose, were analyzed in 2-month-old dairy calves. Based on previously determined protective anti-BoNT/D antibody levels analyzed in field outbreaks, the immune response to type D toxoids was analyzed using an in-house ELISA system. Here we show that using the current vaccination strategy of using a priming dose in 2-month-old calves followed by booster doses after 4 weeks and annually thereafter, did not result in continuous protective levels of anti-BoNT/D antibodies. As a result of this vaccination protocol, only 15-31% of cattle in parities 1-3 were protected at the time of the annual booster. Vaccination study in calves indicated that adding a 6-month booster dose to the current protocol resulted in continuous protective levels of anti-BoNT/D antibodies well above the cut-off protective levels. The presence of maternally derived anti-BoNT/D antibodies did not interfere with the immune response to toxoids that can be administered to 2-month-old calves.

Quantitative analysis of levels of serum immunoglobulin G against botulinum neurotoxin type D and association with protection in natural outbreaks of cattle botulism

The recent outbreaks of cattle botulism in vaccinated Israeli dairy cattle prompted us to determine vaccine efficacy and reasons for vaccine failure. Analysis of clinical signs, feeding practice, vaccination history, and epidemic curves enabled us to define a study population in two outbreaks, where high doses of Clostridium botulinum neurotoxin type D (BoNT/D) were evenly consumed by the affected animal groups. Attack rates among unvaccinated 6- to 24-month-old heifers were 96% (55/57) and 85% (53/62). The attack rates in vaccinated parity 1, 2, and >or=3 cows were 40.4% (21/52), 14.3% (4/28), and 5.6% (3/54), respectively. Vaccine efficacies for these cow groups were 52.5%, 83.2%, and 93.4%, respectively. In younger, unvaccinated 2- to 6-month-old calves, presumably protected by maternal antibodies, the attack rate was 24% (17/71). These differences correlated with significant differences in levels of specific anti-BoNT/D antibody in serum by an enzyme-linked immunosorbent assay (ELISA). The ELISA performance for predicting protection was analyzed by receiver operating characteristic analysis and was found to be highly significant, with an area under the curve of 0.941 (standard error, 0.034; 95% confidence interval, 0.875 to 1.008; P < 0.000). No animals with serum ELISA unit levels above 0.33 were affected in these exposed groups. At this cutoff level, the specificity of the ELISA was 100%, sensitivity was 67%, and accuracy was 92%. We concluded that botulinum toxoids can confer adequate protection against natural exposure to lethal doses of BoNT/D; however, the vaccination protocols should be optimized. Our in-house ELISA system will enable us to optimize vaccination protocols in the animal population.

Esporos e toxinas de Clostridium botulinum dos tipos C e D em cacimbas no Vale do Araguaia, Goiás

Foram avaliadas a ocorrência e distribuição de esporos e toxinas de Clostridium botulinum tipos C e D em 300 cacimbas empregadas como bebedouro de bovinos em 130 propriedades rurais localizadas em 12 municípios do Vale do Araguaia, Estado de Goiás. A presença de esporos foi determinada indiretamente pelo cultivo em meio de cultura, seguido da inoculação e neutralização em camundongo das amostras de sedimento do interior das cacimbas, e do solo superficial e fezes de bovinos, coletadas ao seu redor. A presença de toxina foi avaliada diretamente pela inoculação em camundongo do sedimento filtrado das cacimbas, também seguida da neutralização em camundongo com antitoxinas C e D. A presença de esporos de C. botulinum foi significativamente maior (p<0,05) nas fezes de bovinos (31%), quando comparadas com os resultados das amostras de solo superficial (19%) e dos sedimentos (10%). Foram detectadas toxinas botulínicas dos tipos C, D, ou classificadas como pertencentes ao complexo CD, em seis amostras (2%) das 300 cacimbas. Das 130 propriedades trabalhadas, em 122(93,85%) foram encontrados esporos ou toxinas de Clostridium botulinum em pelo menos uma das variáveis pesquisadas, enquanto somente 8(6,15%) não apresentaram qualquer contaminação A idade e profundidade das cacimbas estiveram associadas com a freqüência de detecção de esporos e toxinas. Assim, quanto mais velhas e rasas, maior a freqüência do isolamento de esporos e toxinas. A contaminação das cacimbas do Vale do Araguaia goiano com esporos e toxinas do Clostridium botulinum tipos C e D demonstra o risco potencial permanente e crescente para a ocorrência da intoxicação botulínica de origem hídrica nos bovinos.

Application of PCR for Detection of Clostridium botulinum Type D in Bovine Samples

Diagnosis of botulism in cows is obtained by detecting the neurotoxin and/or Clostridium botulinum in the suspected animal. The standard method for detecting the toxin is the mouse bioassay. However, in recent years, the use of mice has become very costly and inconvenient in some facilities, and public pressure has been increasing to find alternatives to live animal bioassays. In this manuscript, we describe the use of the polymerase chain reaction (PCR) procedures in the diagnosis field cases of bovine type D botulism. Bovine samples from clinical cases diagnosed as C. botulinum type D according by clinical symptoms and bioassay resulted in expected PCR product ( approximately 497 bp) similar to the C. botulinum type D NCTC 8265 strain while the gene product was confirmed by sequence data.

Natural Clostridium botulinum type C toxicosis in a group of cats

Clinical signs of botulism were observed in a group of eight cats, four of which died, after being fed pelican carrion. Clostridium botulinum type C was isolated from one cat. The microorganism and its toxin were found in the pelican. This is apparently the first report of natural botulism in cats.