Anthrax

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bacillus anthracis spores under light microscopy
Epistaxis commonly seen in cattle which have died from anthrax

Anthrax is a pathogenic zoonotic notifiable bacterial disease of cattle that causes cattle disease and deaths worldwide.

Anthrax is caused by Bacillus anthracis and infections in cattle often result in sporadic outbreaks characterised by acute septicemia with a high fatality rate, often accompanied by hemorrhagic lymphadenitis[1]. This disease is still endemic in many regions in developing countries[2].

In dogs, humans, horses, and pigs, it is usually less acute. Humans become infected by butchering sick animals, handling raw meat or contact with infected animals[3].

Clinical signs

Affected cattle often present with fever, anorexia, epistaxis, dyspnea, ataxia and sudden death. Affected herds show acute clinical cases interrupted by relatively long, mostly dormant phases[4].

Postmortem findings are consistent with generalized vasculitis, with engorgement of spleen and liver. Rigor mortis is frequently absent or incomplete.

Diagnosis

Diagnosis can be suggested by clinical findings but accurate laboratory assessment is required by bacterial culture, immunoflourescence and PCR assays[5].

A differential diagnosis would include Clostridium spp infections, bloat, lightning strike, Leptospira spp, Anaplasma spp and bracken fern poisoning.

Treatment

The use of long-acting broad-spectrum antimicrobial therapy is required in valuable cattle. This would include tetracyclines, gentamicin, amoxycillin, enrofloxacin or ceftiofur.

Government-regulated vaccination schedules are usually implemented with modified live vaccines[6]. Vaccination has been highly effective in preventing anthrax on farms, specifically if given prior to the season in which outbreaks generally occur[7].

Rapid detection and reporting, quarantine and burning or burial of suspect and confirmed cases is usually mandatory[8].

References

  1. Merck Vet Manual
  2. Scarlata F et al (2010) The return of anthrax. From bioterrorism to the zoonotic cluster of Sciacca district. Infez Med 18(2):86-90
  3. Chakraborty A et al (2012) Anthrax outbreaks in Bangladesh, 2009-2010. Am J Trop Med Hyg 86(4):703-710
  4. Pilo P & Frey J (2011) Bacillus anthracis: molecular taxonomy, population genetics, phylogeny and patho-evolution. Infect Genet Evol 11(6):1218-1224
  5. Ndiva Mongoh M et al (2007) Characterization of an outbreak of anthrax in animals in North Dakota: 243 cases (2005) Bov Prac 41:101–109
  6. Ndiva Mongoh M et al (2008) A Review of Management practices for the control of anthrax in animals: The 2005 anthrax outbreak in North Dakota — Case study. Zoonoses Pub Health 55:279–290
  7. Ndiva Mongoh M et al(2008) Risk factors associated with anthrax outbreak in animals in North Dakota, 2005: A retrospective case-control study. Public Health Rep 123:352–359
  8. Chikerema SM et al (2012) Temporal and spatial distribution of cattle anthrax outbreaks in Zimbabwe between 1967 and 2006. Trop Anim Health Prod 44(1):63-70