Epidemiological Mapping of Canine Angiostrongylosis in Portugal: Findings from a Nationwide Prevalence Survey

TL;DR

This study maps the spread of a parasitic disease in dogs across Portugal, finding it more common in northern and central regions and linked to outdoor lifestyles and male sex.

Contribution

The study provides the first nationwide prevalence data on canine angiostrongylosis in Portugal, identifying new affected regions and risk factors.

Findings

A 1.13% prevalence of Angiostrongylus vasorum was detected in 1059 dogs across Portugal.

Higher infection rates were observed in northern and central districts, including previously unaffected areas like Leiria and Beja.

Male sex and an outdoor lifestyle were identified as significant risk factors for infection.

Abstract

Canine angiostrongylosis is a globally distributed parasitic disease that is expanding across Europe. In Portugal, epidemiological data remain scarce, despite geo-climatic conditions that are highly conducive to parasite transmission. This study aimed to detect the presence of circulating Angiostrongylus vasorum antigens in dogs across mainland and insular Portugal and to identify potential risk factors for infection. Among the 1059 dogs tested, a prevalence of 1.13% was observed, with positive cases predominantly located in the north-central regions, including previously unaffected areas. An outdoor lifestyle and male sex were identified as risk factors. These findings confirm the presence of established lungworm infection and suggest a northward spread, underscoring the importance of enhanced clinical awareness and epidemiological surveillance.

Considering the global health concern and the significant morbidity associated with canine angiostrongylosis, this study aimed to update the epidemiological profile and geographic distribution of the disease in canine populations across all continental and insular districts of Portugal, some of which were never studied before. A total of 1059 dogs were included in the study and tested for Angiostrongylus vasorum antigens using a commercial immunochromatographic assay. The overall prevalence was 1.13%. Higher infection rates were found in northern (3.9% in Viana do Castelo) and central (3.6% in Viseu and 3.8% in Lisbon) districts, and infection was reported, for the first time, in the districts of Leiria and Beja. The mild temperatures and elevated humidity levels, characteristic of Portugal’s northern and coastal regions, promote increased gastropod host activity and population density while also accelerating parasite development. The effect of wildlife reservoirs must also be considered, since higher seroprevalences were detected recently in red foxes from Portuguese northern regions. Bivariate Chi-square test analysis identified male sex and an outdoors lifestyle as risk factors. These findings confirm the enzootic presence of A. vasorum throughout the country and highlight the need for increased clinical awareness, routine screening, and the implementation of effective prophylactic strategies.

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