Aspergillus spp

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Placentitis associated with mycotic abortion in cows

Aspergillus spp are a group of soil mould which are an aerosol cause of mycotic abortion, respiratory diseases and aflatoxicosis in cattle worldwide[1].

Species of Aspergillus which are pathogenic to cattle include:

  • Aspergillus fumigatus
  • Aspergillus terreus
  • Aspergillus flavus[2]

In affected cattle, infections with Aspergillus may be asymptomatic. In respiratory aspergillosis, respiratory symptoms such as coughing, dyspnea and hemoptysis may be apparent. In some cattle, this can be rapidly fatal as dissemination of spores occurs through the pulmonary circulation.

Mycotic placentitis, also caused by Aspergillus spp, is usually a sporadic cause of abortion affecting a small percentage of cattle in a herd. Cattle housed in the winter can experience an abortion rate of up to 30% due to mycotic placentitis, if feed or bedding is heavily contaminated with molds. Ingested mold is thought to localize in the cows' intestinal tract and then spread to the placenta through the blood. High rates of mycotic placentitis have also been correlated with heavy rainfall during the haymaking season, episodes of subclinical grain overload and with prolonged intensive antibiotic treatment.

On postmortem, affect lungs contain multiple discrete granulomas, and the disease grossly resembles tuberculosis[3].

Diagnosis is based on presenting clinical signs, supplemented with isolation and culture of Aspergillus spp' from lung or uterus of necropsied cattle. Additional tests include immunoflouresce, ELISA and PCR assays.

A differential diagnosis would include other causes of mycotic abortion such as Lichtheimia corymbifera and Mortierella wolfii[4].

Treatment may be difficult. Itraconazole (3 mg/kg, bid for 84–120 days) may be effective for valuable cattle.

References

  1. Glover AD et al (2011) Pathology in practice. Mycotic abortion. J Am Vet Med Assoc 239(3):319-321
  2. Lanier C et al' (2012) Recurrence of Stachybotrys chartarum during mycological and toxicological study of bioaerosols collected in a dairy cattle shed. Ann Agric Environ Med 19(1):61-67
  3. Merck Vet Manual
  4. Piancastelli C et al (2009) Isolation and characterization of a strain of Lichtheimia corymbifera (ex Absidia corymbifera) from a case of bovine abortion. Vet Rec 134(11):263-266