Vector-borne diseases are a significant, growing problem in human and veterinary medicine. These illnesses are transmitted by arthropod vectors, and companion animals may be their reservoir for other animals and people.
The emergence of vector-borne diseases may be driven by several factors, including climate change, deforestation, land-use change, urbanisation, human population growth and migration, habitat fragmentation, animal movements and biodiversity loss (11). These factors may influence the emergence of biological vectors of infectious and parasitic diseases in areas previously free from them. This is confirmed by, for example, changes in the geographical distribution of important tick vectors, such as
Poland is a country where vector-borne diseases such as babesiosis (caused by
The aim of the study was to monitor the occurrence of vector-borne diseases in dogs arriving in or returning to Poland from areas where these diseases are endemic.
The study was conducted in the years 2021–2023. It included 497 anaemic dogs of different breeds aged from 6 months to 14 years. The sex distribution was 297 male and 200 female dogs. The dogs which came to Poland from Ukraine totalled 184: 16 in 2021, 141 in 2022, and 27 in 2023. Other animals returned to the country from spring or summer holidays spent in Croatia (96 dogs: 28 in 2021, 31 in 2022 and 37 in 2023), Turkey (79 dogs: 8 in 2021, 42 in 2022 and 29 in 2023), Italy (48 dogs: 26 in 2022 and 22 in 2023), Bulgaria (42 dogs: 19 in 2021, 16 in 2022 and 7 in 2023), Albania (36 dogs: 3 in 2021, 20 in 2022 and 13 in 2023) and Romania (12 dogs: 1 in 2021, 8 in 2022 and 3 in 2023) (Table 1).
Non-indigenous and travelling dogs screened for vector-borne diseases, by country of origin or destination
Country | Number of examined dogs | Number of dogs protected against ectoparasites | Number of infected dogs | Number of infected dogs protected against ectoparasites |
---|---|---|---|---|
Ukraine | 184 | 36 | 39 | 4 |
Croatia | 96 | 72 | 7 | 2 |
Turkey | 79 | 65 | 16 | 3 |
Italy | 48 | 42 | 6 | 1 |
Bulgaria | 42 | 30 | 4 | 1 |
Albania | 36 | 31 | 4 | 0 |
Romania | 12 | 8 | 3 | 0 |
Total | 497 | 284 | 79 | 11 |
In anamnesis, information was obtained about any anti-ectoparasite prophylaxis which had been sought for the animals. This had been administered to 36 of the dogs from Ukraine and 72 dogs spending holidays in Croatia, 65 having been in Turkey, 42 in Italy, 30 in Bulgaria, 31 in Albania and 8 in Romania.
The animals demonstrated different clinical symptoms (Table 2). Haematological examination revealed anaemia in all dogs and thrombocytopaenia in 413 of them (Table 3). Blood was collected from all animals for molecular testing to analyse for selected vector-borne diseases (babesiosis, anaplasmosis, ehrlichiosis, haemotropic mycoplasmosis, leishmaniasis, hepatozoonosis and bartonellosis). The study was conducted in accordance with the Directive of the European Parliament on the protection of animals used for scientific purposes (Directive 2010/63/EU), and all owners of the dogs agreed to their inclusion in the study. Blood sampling was a part of the clinical procedure and no local ethics committee approval was required.
Clinical signs observed in non-indigenous and travelling dogs with vector-borne diseases
Identified pathogen | Number of infected dogs | Number of dogs with the particular clinical sign | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Apathy | Fever | Pale mucus membranes | Icterus | Lameness/muscle pain | Gastroenteric problems | Neurological signs | Discolouration of the urine | Dermatological signs | Epistaxis | ||
27 | 27 | 19 | 23 | 4 | 0 | 10 | 0 | 24 | 0 | 0 | |
2 | 2 | 2 | 2 | 0 | 0 | 0 | 0 | 2 | 0 | 0 | |
20 | 20 | 11 | 6 | 0 | 4 | 3 | 1 | 0 | 0 | 4 | |
15 | 15 | 8 | 15 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
7 | 7 | 5 | 6 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | |
4 | 4 | 3 | 3 | 0 | 2 | 1 | 0 | 0 | 1 | 2 | |
3 | 3 | 1 | 3 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | |
No infection | 418 | 379 | 306 | 361 | 16 | 4 | 83 | 4 | 0 | 2 | 0 |
Total | 497 | 458 | 356 | 420 | 20 | 12 | 98 | 5 | 26 | 4 | 6 |
P-value | 0.002 | 0.078 | 0.016 | 0.540 | 8.517 × 10−5 | 0.999 | 0.581 | 2.200 × 10−16 | 0.121 | 1.369 × 10−5 |
Haematological disorders observed in non-indigenous and travelling dogs with vector-borne diseases
Identified pathogen | Number of infected dogs | Number of dogs with the particular haematologicaldisorder | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Anaemia | Thrombocytopaenia | Normal PLT | Leukocytosis | Leukopaenia | Normal WBC | ||||||
27 | 27 | 27 | 0 | 2 | 21 | 4 | |||||
2 | 2 | 2 | 0 | 1 | 1 | 0 | |||||
20 | 20 | 20 | 0 | 3 | 1 | 16 | |||||
15 | 15 | 9 | 6 | 10 | 0 | 5 | |||||
7 | 7 | 7 | 0 | 2 | 0 | 5 | |||||
4 | 4 | 4 | 0 | 0 | 1 | 3 | |||||
3 | 3 | 1 | 2 | 3 | 0 | 0 | |||||
1 | 1 | 0 | 1 | 1 | 0 | 0 | |||||
No infection | 418 | 418 | 343 | 75 | 26 | 19 | 373 | ||||
Total | 497 | 497 | 413 | 84 | 48 | 43 | 406 | ||||
P-value | - | 0.191 | 0.191 | 1.807 × 10−7 | 1.949 × 10−10 | 2.200 × 10−16 |
PLT – platelet count; WBC – white blood cell count
Each sample was labelled with a unique number without details of the owner of the dog. All blood samples were analysed in a BIONOTE Vcheck M10 analyser (VetExpert, Poland), which isolated whole blood DNA and amplified the DNA of
Primers and PCR conditions for detection and identification of
Pathogen | Primers | Target gene | Amplicon size (base pairs (bp)) | PCR conditions | Reference |
---|---|---|---|---|---|
EHR 521: (5′-TGT AGG CGG TTC GGT AAG TTA AAG-3′) |
16S RNA | 247 bp | 35 cycles: denaturation at |
Pancholi |
|
BAB GF2: (5′-GTC TTG TAA TTG GAA TGA TGG-3′) |
18S RNA | 559 bp | 50 cycles: denaturation at |
Adaszek and Winiarczyk (3) | |
d3: (5′-TCC GTT CCC ACA ACA-CCA GC- 3′) |
P18/BgTRAP | 182 bp | 50 cycles: denaturation at |
Fukumoto |
|
BART-LC-GEN-F: (5′-ATG GGT TTT GGT CAT CGA GT-3′) |
Citrate synthase | 250 bp | 40 cycles: denaturation at |
Staggemeier |
|
HepF: (5′-ATA-CAT-GAG-CAA-AAT-CTC- AAC-3′) |
18S RNA | 666 bp | 34 cycles: denaturation at |
Inokuma |
|
SYBR_TGA ACG ATG AA-3′) |
16S RNA | 103 bp | 40 cycles: denaturation at |
Willi |
|
N13A(5′-AAC TTT TCT GGT CCT CCG GG-3′) |
kinetoplast DNA minicircle | 120 bp | 40 cycles: denaturation at |
Francino |
The size of the groups recommended using Fisher’s exact test to evaluate the effectiveness of ectoparasite prevention. The null hypothesis assumed that the two categorical variables are independent,
Molecular tests revealed the presence of vector-borne pathogens in 79 dogs. The most commonly diagnosed infection was
The majority of infected animals presented typical symptoms of specific vector-borne diseases (Table 2). The performed haematological examinations revealed anaemia (in all 79 dogs), thrombocytopaenia (in 70 dogs), leukopaenia (in 24 dogs) and leukocytosis (in 22 dogs). In 33 dogs from this group (41.8%), the white blood cell count was within the reference range. Relating this result to the group of animals in which no vector-borne infection was found by molecular testing and in 373 of which a leukocyte count in the reference range was found (89.2%), it can be concluded that this difference was statistically significant (P-value = 2.200 × 10−16).
Most of the sick dogs (n = 39) came from Ukraine. Of these, 15 were infected with
Results of vector-borne disease pathogen isolation and amplification from samples of non-indigenous and travelling dogs by country of origin or destination
Country | Number of dogs infected with the particular pathogen | ||||||||
---|---|---|---|---|---|---|---|---|---|
Total | |||||||||
Ukraine | 15 | 0 | 12 | 1 | 0 | 0 | 8 | 3 | 39 |
Croatia | 6 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 7 |
Turkey | 0 | 0 | 4 | 0 | 3 | 1 | 4 | 4 | 16 |
Italy | 1 | 0 | 2 | 2 | 0 | 0 | 1 | 0 | 6 |
Bulgaria | 2 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | 4 |
Albania | 1 | 1 | 0 | 0 | 0 | 0 | 2 | 0 | 4 |
Romania | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 3 |
Total | 27 | 2 | 20 | 4 | 3 | 1 | 15 | 7 | 79 |
Only four of the positive animals from Ukraine had received prophylaxis against ectoparasites in the previous three months. Of the animals that became infected while on holiday, only two dogs had received prophylaxis against ectoparasites before travelling to Croatia, three before travelling to Turkey, one to Italy and one to Bulgaria, and none had before travelling to Albania or Romania (Table 6).
The effectiveness of ectoparasite prevention and probability of infection in the group of protected non-indigenous and travelling dogs
Country | Number of protected and infected dogs | Number of non-protected and infected dogs | Number of protected and non-infected dogs | Number of non-protected and non-infected dogs | P-value | 95 % confidence interval | Odds ratio |
---|---|---|---|---|---|---|---|
Ukraine | 4 | 35 | 32 | 113 | 0.115 | 0.097–1.260 | 0.405 |
Croatia | 2 | 5 | 70 | 19 | 0.009 | 0.009–0.747 | 0.111 |
Turkey | 3 | 13 | 62 | 1 | 2.845 × 10−11 | 9.562 × 10−5–4.478 × 10−2 | 0.005 |
Italy | 1 | 5 | 41 | 1 | 2.062 × 10−5 | 1.123 × 10−4–1.262 × 10−1 | 0.007 |
Bulgaria,Romania and Albania | 1 | 10 | 61 | 18 | 2.007 × 10−5 | 6.752 × 10−4–2.415 × 10−1 | 0.031 |
Total | 11 | 68 | 266 | 152 | 2.200 × 10−16 | 0.042–0.184 | 0.092 |
The effectiveness of ectoparasite prevention was verified using the F test, in which for all countries except Ukraine, H0 was rejected (confidence intervals ≠ 1), and the P-values indicate that there were statistically significant differences between the groups. For the data collected in this study, the odds ratios suggest that the probability of infection is between 0.11 and 0.005 lower in the group of protected dogs (Table 6).
The results of our studies indicate that both the increased frequency of tourist trips with pet dogs to countries where vector-borne diseases are endemic and the influx of immigrants with their dogs from Ukraine to Poland may constitute risk factors for the occurrence of a wider range of diseases than covered in this report and diseases considered exotic in this country.
It is commonly known that the countries which the study dogs visited or from which they originated are endemic areas for vector-borne diseases. It is confirmed by numerous literature data. In Ukraine, such pathogens as
In Italy, the vector-borne pathogens most frequently affecting dogs include
In Bulgaria, antibodies to
Since the beginning of the war in Ukraine, the Polish–Ukrainian border has been crossed by millions of refugees, mostly women and children, very often with pets (26). After the Russian aggression against Ukraine, to facilitate refugees’ passing through the border with pets, the Chief Veterinary Officer temporarily simplified the procedure for dealing with animals translocated for non-commercial purposes and accompanying refugees entering the EU from Ukraine through the Polish border (17). This procedure was designed to control rabies and focused on ensuring effective vaccination against it in dogs, cats and ferrets and tracking the identity (
While infection with
So far, data on the occurrence of these diseases in dogs in Poland are fragmentary. The first cases of hepatozoonosis caused by
A single case of canine leishmaniosis in Poland has been described so far. A three-year-old stray female dog was admitted to a veterinary clinic for generalised skin lesions and lethargy. Canine leishmaniosis was confirmed by several diagnostic methods: cytology (impression smears from skin lesions and fine-needle aspiration from lymph nodes), histopathology (skin biopsies) and serology (ELISA and IFAT) (41). As no history of the dog was available, it was assumed that the dog was infected somewhere in southern Europe (18).
The presence of
Suspicion of vector-borne diseases is based on information obtained from the owners during the anamnesis, clinical examination and additional tests. Haematological examination may show abnormalities characteristic of some of the nosological entities in question. They include anaemia, thrombocytopaenia and leukopaenia in the course of babesiosis (4, 42, 48, 54), thrombocytopaenia in the course of anaplasmosis, ehrlichiosis and bartonellosis (6, 40, 45), and anaemia in the course of haemotropic mycoplasmosis (46). These data overlap with our observations; however, it should be noted that the dogs in which no vector-borne diseases were found by molecular testing also presented symptoms of anaemia (it was a criterion for inclusion in the study) and, in the majority of animals, symptoms of thrombocytopaenia. The only statistically significant difference observed in haematological examinations between the infected and uninfected dogs was the leukocyte count. In the group with negative results of PCR tests for vector-borne diseases, only 10.8% of the dogs had abnormal leukocyte counts, compared to 58.2% of the infected dogs. A definitive diagnosis of vector-borne diseases must therefore be supported in each case by more sensitive diagnostic methods.
Undoubtedly, a factor contributing to the development of vector-borne diseases is omission of proper protective measures against ectoparasites. Only 11 (13.9%) of the 79 studied infected dogs had benefited from ectoparasite prevention measures, and 68 (86.1%) of those 79 had not been protected. These data were statistically significant. Currently, there are numerous medications on the veterinary products market that reliably prevent ectoparasite infestations. They are available in different versions: spot-on, tablets, collars,
Our observations and the above review of the literature indicate that although vector-borne diseases occur in dogs in Poland, that the number of their cases is increasing in the country undoubtedly has its main factor in the migration crisis and increasingly frequent trips of owners with their dogs to areas of endemic infectious and parasitic diseases. Among dogs returning from holidays and arriving in Poland from abroad, constant screening for these diseases using analytic techniques that can detect several pathogens simultaneously and quickly seems to be crucial for their early recognition and introduction of appropriate therapy.
Since many vector-bone diseases are zoonoses, their proper monitoring and adequate prevention against ectoparasites in dogs are also important elements of human health protection.