First epidemiological data on pathogenic leptospires isolated on the Azorean islands

Area of Science:

• Veterinary Microbiology
• Zoonotic Diseases
• Island Ecology

Background:

• Leptospira interrogans serovars are pathogenic bacteria transmitted through animal reservoirs.
• Previous investigations on Leptospira in the Azores Archipelago were limited.
• Small mammals are known reservoirs for various infectious agents.

Purpose of the Study:

• To investigate the prevalence and diversity of Leptospira interrogans serovars in insectivores and rodents in the Azores.
• To identify the primary mammalian reservoirs of Leptospira on different Azorean islands.
• To assess the potential risk of leptospirosis transmission to humans and livestock.

Main Methods:

• Bacteriological culture of kidney samples from insectivores (Erinaceus europaeus) and rodents (Rattus rattus, R. norvegicus, Mus musculus).
• Serological testing for specific agglutinins against isolated Leptospira strains.
• Analysis of isolation rates and prevalence across different islands of the Azores Archipelago.

Main Results:

• Three distinct Leptospira interrogans s.l. serovars (copenhageni, icterohaemorrhagiae, ballum) were identified.
• House mice (Mus musculus) and black rats (Rattus rattus) were the major reservoirs, with isolation rates up to 88% and 33% respectively in São Miguel.
• Significant island variation in prevalence was observed, with higher rates noted in Terceira and São Miguel.

Conclusions:

• Small mammals in the Azores serve as important sylvatic reservoirs for pathogenic Leptospira.
• The identified Leptospira serovars represent a novel finding for the region.
• The prevalence and distribution suggest a potential public and livestock health risk, particularly on Terceira and São Miguel islands.