The impact of the climate on the epidemiology of Dirofilaria immitis in the pet population of the Canary Islands

In the last 15 years, a slight increase in heartworm can be confirmed in most autonomous communities, with decreasing prevalences or similar values only in Aragon, Catalonia, Valencian Community, Madrid and Castilla y León.

“in the last 15 years a slight increase in heartworm can be confirmed in most of the autonomous communities, with decreasing prevalences or with similar values only in Aragon, Catalonia, Valencian Community, Madrid and Castilla y León.”

In the Canary Islands, prevalences have remained similar or with slight oscillations during the last 20 years, although the presence of the parasite is reported for the first time in Lanzarote.

“the prevalences have remained similar or with slight oscillations during the last 20 years [9,12,27,28,29], although the presence of the parasite is reported for the first time in Lanzarote.”

Dogs living indoors showed significantly lower prevalences because they are less exposed to vector mosquitoes.

“Regarding habitat, dogs living indoors showed significantly lower prevalences, as shown in other similar studies [8,9,11,12,13,19]. As has been pointed out in previous studies, animals that live indoors are less exposed to the presence of vector mosquitoes and, thus, prevalences are lower.”

In the Canary Islands, previous research has shown higher prevalence in the past, demonstrating that prevalence has gradually decreased over the years, probably due to prevention campaigns by veterinarians.

“In the Canary Islands, previous research has shown higher prevalence in the past, demonstrating that prevalence has gradually decreased over the years, probably due to prevention campaigns carried out by”

A previous study in the Canary Islands demonstrated hyperendemic status, showing feline seroprevalence of 18.1%, with disparity by island from 0% in El Hierro to 24.1% in Tenerife.

“Moreover, a previous study carried out in the Canary Islands demonstrated the hyperendemic status of the islands, showing a seroprevalence of 18.1%, although a remarkable disparity was found when evaluating the results by island separately, which ranged from 0% in El Hierro to 24.1% in Tenerife [18].”

On Gran Canaria, feline seroprevalence was 18.3% in 2004, 21.3% in 2016, and 22.9% in 2022, demonstrating a slow but constant increase in feline seroprevalences.

“Moreover, on the island of Gran Canaria, a seroprevalence of 18.3% was recorded in cats in 2004 [119], so the results of the latest studies being 21.3% in 2016 [18] and 22.9% in 2022 [17] demonstrates a slow but constant increase in feline seroprevalences [120].”

In Spain, only epidemiological studies of feline heartworm have been published in the Canary Islands, Madrid, Barcelona and Zaragoza.

“in Spain, there are only published epidemiological studies in the Canary Islands, Madrid, Barcelona and Zaragoza (10–14).”

The highest antibody seroprevalences appear in areas of the southern peninsula, the Mediterranean regions, and the Canary Islands.

“The highest antibody seroprevalences appear in areas of the southern peninsula and the Mediterranean regions, as well as the Canary Islands”

No statistically significant differences in antibody seroprevalence were found based on sex.

“No statistically significant differences were found based on sex, as has been published in previous studies (12, 13, 27).”

In the subtropical climate of the Canary Islands, the present results show a slight increase in antibody seroprevalence, from 18.1 to 19.2%.

“the present results show a slight increase in the antibody seroprevalence, from 18.1 to 19.2% (7, 12).”

The prevalence of Dirofilaria spp. in cats varies from 0 to 33% across Europe.

“The prevalence of Dirofilaria spp. in cats varies from 0 to 33% across Europe [11, 30–40].”

The present results report the first epidemiological data on feline D. immitis in Madrid.

“Regarding cats, the present results report the first epidemiological data on feline D. immitis and demonstrate the presence of feline heartworm in Madrid.”

In cats, a great variability in prevalences by age ranges can be observed when the results are compared with other studies.

“In cats, a great variability in the prevalences by age ranges can be observed when the results were compared with other studies [7, 14–16, 29].”

The prevalences obtained for dirofilariosis in this study maintain similar values with respect to areas evaluated in the last 5-6 years, such as Barcelona, Madrid, Salamanca, or the Canary Islands.

“the prevalences obtained in this study maintain similar values with respect to the areas that had been evaluated in the last 5–6 years, such as Barcelona, Madrid, Salamanca, or the Canary Islands”

Other epidemiological studies found no significant gender differences in Dirofilaria infections, while others did.

“although other epidemiological studies found no significant differences (9, 14, 34), these differences were also observed in others (7, 8, 70).”

The efficacy of preventive measures against D. immitis has been observed in Gran Canaria with a constant decrease of prevalences across 15 years.

“The efficacy of the preventive measures against D. immitis has been observed in Gran Canaria with a constant decrease of the prevalences across 15 years (8, 70, 75).”

Previous epidemiological studies have obtained different results when dogs were assessed by age, with statistical significance between age groups in some studies but not in others.

“Previous epidemiological studies have obtained different results when the dogs were assessed by age, finding statistical significance between age groups in some epidemiological studies of vector-borne diseases but not in others (8, 9, 46).”

Studies investigating anti-D immitis antibodies in cats show that the rate of exposure to infection is much higher.

“studies investigating anti-D immitis antibodies in cats show that the rate of exposure to infection is much higher.”

Climatic differences in humidity levels have a great impact on the risk of exposure for susceptible hosts.

“Adequate preventive treatment covering the whole of the transmission season is crucial for effective prevention, and a year-round approach is often the best option because of climatic differences in humidity levels having a great impact on the risk of exposure for susceptible hosts, as discussed earlier. 16”