Occurrence of Fungi of Public Importance in Rodents Trapped along and inside Grain Storage Facilities in Mbeya Municipal, Tanzania.

Abstract

This work was supported by the African Centre of Excellence for Innovative Rodent Pest Management and Biosensor Technology Development (ACE IRPM and BTD) at the Institute of Pest Management of the Sokoine University of Agriculture.

Abstract

Rodents act as agents for the dispersal of pathogenic entities including fungi and enable their colonization in new areas. They interact with the human environment which acts as a route for the transmission of pathogens. A total of 210 rats were trapped in and along the storage facilities in selected wards in Mbeya city. Fresh fecal samples were collected from the intestines by dissecting the abdominal part of the rodent to obtain pellets. Samples were kept in clean envelopes and preserved at -20 ⁰C at Mbeya National Research Institute (NIMR) for further laboratory analysis. Fungi were isolated by culturing in selective media and identification was done by colony morphology. Further confirmation of the isolated Aspergillus flavus was done by nested PCR to confirm the presence flR the gene in the isolates. Aflatoxigenicity of the isolated A. flavus was tested with a controlled experiment in which non-contaminated maize kernels were inoculated with the fungal spores and incubated for up to 15 days and accumulation of the aflatoxin analyzed by indirect competitive ELISA. Aspergillus fumigatus was the dominant fungal specie from the cultured samples, with a prevalence of 26% followed by Aspergillus niger and Fusarium species, both with a prevalence of 9%, Aspergillus flavus 3% and Aspergillus ochraceus 1%.  Indirect competitive ELISA was performed on 10 maize samples that were infected with A. flavus isolates, 10 maize samples free from isolates contamination, and 4 pure isolates of A. flavus to check whether the isolates were potential producers of aflatoxins. The four pure isolates had a high concentration of aflatoxin compared to the samples contaminated with A. flavus isolates. These findings justify that rodents harbor pathogenic fungi in their intestinal tracts and act as dispersal agents of the fungi to foods and other human and animal premises. Effective control measures should therefore be applied in protecting foods and premises from rodents, especially mice and rats to minimize risks of disease spread.

Keywords: Pathogenic fungi, Rodents, Aspergillosis, dispersal, and mycotoxin-producing fungi.

DOI: 10.7176/JHMN/109-05

Publication date:July 30^th 2023