CoChat
Sign Up
Cited by 53Parasitic Diseases Research and TreatmentHelminth infection and controlResearch on Leishmaniasis Studies

Prevalence of canine heartworm ( Dirofilaria immitis ) disease in dogs of central Portugal

Open access
Vieira, Ana Luísa, Vieira, Maria João, Oliveira, João Manuel, Simões, Ana Rita, Diez-Baños, Pablo, Gestal, Juan·2014·Parasite
DOI 10.1051/parasite/2014003PMC PMC3927308
Open this paper in CoChat — free accountOpen PDF

Abstract

The aim of the present study was to determine the prevalence and risk factors concerning Dirofilaria immitis infection in dogs from Figueira da Foz, located in the central region of Portugal. In the period between November 2009 and January 2011, 304 blood samples were obtained from dogs over 1 year of age, with no previous history of heartworm prevention or diagnosis. Every blood sample was analyzed using varied laboratory techniques (direct microscopic evaluation of a fresh blood sample, the modified Knott technique, and the ELISA antigen detection test - IDEXX Snapp®). In the samples in which microfilaremia was detected, a histochemical technique using acid phosphatase staining was applied to identify the species of microfilariae. A total prevalence of 27.3% (83 out of 304) was found. We also found that 73.5% of all positive cases (61 out of 83) were microfilaremic, and 26.5% were occult infections (22 out of 83). By means of a histochemical technique Dirofilaria immitis was identified in 96.7% of microfilaremic samples. A multivariate model allowed us to identify the following risk factors for the presence of heartworm disease: age between 4 and 9 years, dogs living in a rural environment, large breed dogs, and living outdoors. This study shows for the first time the high prevalence of heartworm disease in a central area of Portugal and emphasizes the importance of systematic screening for this disease, as well as the need to prevent it in dogs in this area.

AI snapshot

Written from the paper’s full text.

TL;DR

This cross-sectional study found a high prevalence of canine heartworm (*Dirofilaria immitis*) in Figueira da Foz, central Portugal, with 27.3% of 304 dogs testing positive. It identifies age 4–9 years, rural environment, large breed, and living outdoors as multivariate risk factors.

Key findings

  • Overall prevalence was 27.3% (83/304; 95% CI 22.4%–32.7%). Among positive dogs, 73.5% (61/83) were microfilaremic and 26.5% (22/83) had occult infections.
  • Diagnostic test prevalences were 19.4% (59/304) by direct smear, 20.1% (61/304) by modified Knott, and 25.7% (78/304) by Snapp® IDEXX antigen test; sensitivities were 71.7%, 73.5%, and 94%, respectively, with 100% specificity for all three.
  • Acid phosphatase histochemical staining identified *D. immitis* in 96.7% (59/61) of microfilaremic samples.
  • Multivariate risk factors were age 4–9 years (OR = 1.65; 95% CI 1.21–2.25; p < .01), rural environment (OR = 15.29; 95% CI 1.93–121.35; p < .05), large breed (OR = 14.31; 95% CI 1.30–157.34; p < .05), and living outdoors (OR = 37.02; 95% CI 3.39–403.91; p < .001). The study also reported that 64% of positive dogs were asymptomatic.

Methods

  • Cross-sectional survey conducted from November 2009 to January 2011 in 18 contiguous parishes of Figueira da Foz, Portugal. A total of 304 dogs over 1 year of age with no previous heartworm prevention or diagnosis were sampled: 247 privately owned dogs and 57 from an animal rescue shelter.
  • Blood samples were analyzed by direct microscopic evaluation of fresh blood, modified Knott technique, and ELISA antigen detection (IDEXX Snapp®). Microfilaremic samples underwent acid phosphatase histochemical staining for species identification. Clinical signs, history, and physical examination findings were recorded.
  • Statistical analysis used SPSS 18.0, chi-square tests, McNemar test, Kappa agreement, and a multivariate model; significance was set at p < 0.05.

Limitations

  • The paper states that information on the distribution and prevalence of *Dirofilaria immitis* in Portugal is incomplete and that more studies are needed; it does not include a dedicated limitations section.
  • Evident from the design: the study is limited to one county in central Portugal and uses dogs presented to a veterinary clinic or from one shelter, so findings may not be representative of all dogs in the region or country.
  • Evident from the diagnostics: microfilarial tests cannot detect occult infections, and the antigen test has reported sensitivity of 84% and may miss low parasite burdens, low-fertility infections, prepatent infections, or male-only infections. The multivariate confidence intervals for rural environment, large breed, and living outdoors are very wide, indicating imprecise effect estimates.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1051/parasite/2014003

Cites

39 of 39 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 30 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    In multivariate analysis, large breed dogs was a risk factor for heartworm disease (OR = 14.31; CI95% 1.30-157.34; p < .05).

    “A multivariate model identified the following risk factors for the presence of heartworm disease: age between 4 and 9 years (OR = 1.65; CI95%: 1.21–2.25; p < .01), dogs living in a rural environment (OR = 15.29, CI95%: 1.93–121.35; p < .05), large breed dogs (OR = 14.31; CI95%: 1.30–157.34; p < .05), and living outdoors (OR = 37.02; CI95%: 3.39–403.91; p < .001).”
    • Also stated in: § Abstract · plain
      “A multivariate model allowed us to identify the following risk factors for the presence of heartworm disease: age between 4 and 9 years, dogs living in a rural environment, large breed dogs, and living outdoors.”
    Quote in the paperSubstantial claim
  • Findingown data

    In bivariate analysis, hunting dogs had a prevalence of 36.2% (p < .05).

    “The following risk factors were therefore determined: dogs aged between 4 and 9 years old (37.8%), medium breed dogs (34.7%), dogs living in a rural environment (38%), dogs living outdoors (37.7%), watchdogs (52.2%), and hunting dogs (36.2%) (p < .05), whereas no significant differences were found related to ownership, pure versus mixed breed, sex or hair length.”
    Quote in the paperSubstantial claim
  • Findingown data

    In multivariate analysis, living in a rural environment was a risk factor for heartworm disease (OR = 15.29; CI95% 1.93-121.35; p < .05).

    “A multivariate model identified the following risk factors for the presence of heartworm disease: age between 4 and 9 years (OR = 1.65; CI95%: 1.21–2.25; p < .01), dogs living in a rural environment (OR = 15.29, CI95%: 1.93–121.35; p < .05), large breed dogs (OR = 14.31; CI95%: 1.30–157.34; p < .05), and living outdoors (OR = 37.02; CI95%: 3.39–403.91; p < .001).”
    • Also stated in: § Abstract · plain
      “A multivariate model allowed us to identify the following risk factors for the presence of heartworm disease: age between 4 and 9 years, dogs living in a rural environment, large breed dogs, and living outdoors.”
    Quote in the paperSubstantial claim
  • Findingown data

    Specificity was 100% for the three diagnostic techniques employed.

    “Specificity was 100% for the three techniques employed.”
    Quote in the paperNot a substantial claim
  • Findingown data

    Cardiac auscultation abnormalities were found in 48.8% of the dogs examined (p < 0.05).

    “The most common physical examination findings in this study were cough (38%), low body condition index (38.2%), increased capillary repletion time (66.7%), cardiac (48.8%), and pulmonary (66.6%) auscultation abnormalities, cardiac murmur (48.7%), and abdominal distention (48.1%). All these findings showed a significantly higher prevalence (p < 0.05).”
    Quote in the paperNot a substantial claim
  • May combine two claims. 13
  • Classified as probably not a substantial claim. 10

  • May combine two claims.

    Findingown data

    The Snapp IDEXX test demonstrated a much higher diagnostic capability, with a substantial level of agreement (Kappa = 0.958).

    “The Snapp IDEXX® test demonstrated a much higher diagnostic capability, with a substantial level of agreement (Kappa = 0.958).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The direct smear test and the modified Knott technique showed the same ability to perform the diagnosis, with no statistical differences (p = 1).

    “The direct smear test and the modified Knott technique showed the same ability to perform the diagnosis, with no statistical differences (p = 1) and a high level of agreement with the dogs’ status of Dirofilaria immitis infection (Kappa = 0.781 and 0.801, respectively).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Five positive samples (6%) tested negative on the Snapp IDEXX test but positive on the modified Knott test and were identified as Dirofilaria immitis by histochemical staining.

    “Five of the positive (6%) samples tested negative when using the Snapp© IDEXX test but tested positive on the modified Knott test and were identified as belonging to D. immitis species by histochemical staining (acid phosphatase activity).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    A high percentage of occult infections is not uncommon and has been previously reported by several studies.

    “This high percentage of occult infections is not uncommon and was previously reported by several studies [23, 25, 39].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [23] McCall, 2008, Veterinary Parasitology source

      Not checked in the free run.

    • cites [25] Meriem-Hind, 2009, African Journal of Agricultural Research

      Not checked in the free run.

    • cites [39] Schrey, 1998, Waltham Focus

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The long parasite development in dogs (7-9 months) and the fact that many infected dogs are asymptomatic for months or years make it difficult to establish a curve during the year for prevalence.

    “Although the period of transmission is restricted to a period of the year because of the relationship of the life of the vector with the weather, the long parasite development in dogs (7–9 months) and the fact that many of the infected dogs are asymptomatic for months or years makes it difficult to establish a curve during the year for prevalence [23] (Figure 1).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] McCall, 2008, Veterinary Parasitology source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Many studies have reported that commercial serological kits have low sensitivity when parasite burdens are low, when worms show low fertility, when microfilariae persist after death of adult females, in prepatent infection, or in male-only infection.

    “Many studies have reported that commercial serological kits have low sensitivity when parasite burdens are low (one to five Dirofilaria immitis adult females), when the worms show low fertility, when the presence of microfilariae persists for 1 to 3 years after the death of adult females, prepatent infection or only male infection [23].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] McCall, 2008, Veterinary Parasitology source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Larger dogs seem to be more attractive for mosquitoes and spend more time outdoors.

    “In agreement with other studies, larger dogs seem to be more attractive for mosquitoes and spend more time outdoors [28, 48].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [28] Montoya, 1998, Veterinary Parasitology source

      Not checked in the free run.

    • cites [48] Yaman, 2009, Journal of Helminthology source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    In this study, living in a rural environment and living outdoors are important risk factors, and the activity of the dog is also a relevant health risk.

    “In this study, living in a rural environment and living outdoors are important risk factors and the activity of the dog is also a relevant health risk. Hunting dogs and watch dogs show higher prevalence.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The pathophysiological response to heartworm infection is mainly due to the presence of adult worms of Dirofilaria immitis in the pulmonary arteries and right ventricle of the heart.

    “The pathophysiological response to heartworm infection is mainly due to the presence of adult worms of Dirofilaria immitis in the pulmonary arteries and right ventricle of the heart [8, 17].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [8] Cringoli, 2001, Veterinary Parasitology source

      Not checked in the free run.

    • cites [17] Kramer LH. 2009. Pathogenesis of Dirofilaria spp. Infections, in Proceedings of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 116–123.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    In Europe, the highest prevalence of heartworm has been reported in Mediterranean countries such as Italy, France, Greece, and Spain.

    “In Europe, the highest prevalence has been reported in Mediterranean countries such as Italy, France, Greece, and Spain [30].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [30] Morchón, 2012, Frontiers in Physiology source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The epidemiological status of dirofilariasis is currently undergoing rapid evolution.

    “The epidemiological status of dirofilariasis is currently undergoing rapid evolution.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [40] Símon, 2009, Trends in Parasitology source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The study was approved by the Ethics Committee of the Clinicão - Veterinary Hospital and all dogs' owners signed an informed consent document.

    “This study was approved by the Ethics Committee of the Clinicão – Veterinary Hospital and all of the dogs’ owners signed an informed consent document.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Dirofilaria immitis is a parasitic nematode infection responsible for canine and feline cardiopulmonary dirofilariasis.

    “Dirofilaria immitis (Leidy, 1856) [18] is a parasitic nematode infection responsible for canine and feline cardiopulmonary dirofilariasis.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] Leidy, 1856, Proceeding of the Academy of Natural Sciences of Philadelphia

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Dirofilaria immitis is a zoonotic parasitic disease mainly located in temperate, tropical, and subtropical areas of the world.

    “It is a zoonotic parasitic disease mainly located in temperate, tropical, and subtropical areas of the world [27, 30]”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [27] Montoya, 2010, Parasitology Research source

      Not checked in the free run.

    • cites [30] Morchón, 2012, Frontiers in Physiology source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In Portugal, a case of human ocular dirofilariasis and two cases of Dirofilaria immitis infection in humans have been reported.

    “In Portugal, a case of human ocular dirofilariasis was reported [15], and two cases of D. immitis infection in humans were reported in Portugal as a consequence of surgical removal and histological examination of larval lung nodules [1].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [15] Gouveia de Almeida, 2011, Acta Medica Portuguesa source

      Not checked in the free run.

    • cites [1] Araújo, 1996, Parassitologia

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Different species of culicid mosquitoes belonging to the genera Culex, Aedes, and Anopheles have been implicated in the transmission of Dirofilaria immitis, allowing its intermediate stage to complete its life cycle.

    “Different species of culicid mosquitoes belonging to the genera Culex, Aedes, and Anopheles, among others, have been implicated in the transmission of this parasite, allowing for its intermediate stage to complete its life cycle [6, 30].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [6] Cancrini G, Kramer LH. 2001. Insect vectors of Dirofilaria spp , in Heartworm Infection in Humans and Animals. Simón F, Genchi C, Eds. Ediciones Universidad Salamanca: Salamanca, Spain. p. 63–76.

      Not checked in the free run.

    • cites [30] Morchón, 2012, Frontiers in Physiology source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Weather is a critical factor because of the climate requirements (high relative humidity and higher than 15 °C average temperature) of the intermediate hosts.

    “Weather is a critical factor because of climate requirements (high relative humidity, and higher than 15 °C average temperature) of the intermediate hosts [28].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [28] Montoya, 1998, Veterinary Parasitology source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The canine heartworm antigen test kit used had sensitivity of 84% (78-89), specificity of 97% (84-100), and accuracy of 86% (81-90).

    “All samples of canine blood were tested for detection of Dirofilaria immitis circulating antigen using a canine antigen test kit (Canine Heartworm Antigen Test Kit, IDEXX Laboratories, Germany) with sensitivity of 84% (78–89), specificity of 97% (84–100), and accuracy of 86% (81–90) [2].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Atkins, 2003, Journal of the American Veterinary Medicine Association source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Heartworm infection is a severe and life-threatening disease.

    “Heartworm infection is a severe and life-threatening disease.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [8] Cringoli, 2001, Veterinary Parasitology source

      Not checked in the free run.

    • cites [17] Kramer LH. 2009. Pathogenesis of Dirofilaria spp. Infections, in Proceedings of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 116–123.

      Not checked in the free run.

19 of 19

  • The paper relies on this without support.

    Occult infections could arise due to low parasite burdens, prepatent infection by young adults, infections by aging adult females with impaired fertility, infections with male-only parasites, or immune response from the host against microfilariae.

    “These infections could arise due to several causes: low parasite burdens, prepatent infection by young adults, infections by aging adult females with impaired fertility, infections with male-only parasites, or immune response from the host against microfilariae.”

  • The paper relies on this without support.

    The climate and socioeconomic life in the region with farming activity (rice culture) provide suitable conditions for development of culicid mosquitoes, vectors of Dirofilaria.

    “The climate and socioeconomic life in the region with farming activity (rice culture) provide suitable conditions for development of culicid mosquitoes, vectors of Dirofilaria.”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • In central coastal regions of Portugal, canine heartworm prevalence has been reported at 15.1%, while in the central region it ranged from 8.8 to 27.3%.

    “Other studies have reported prevalence of 15.1% in the central coastal regions of Portugal, while in the central region, prevalence ranged from 8.8 to 27.3% [12,13,14]”

    From What has happened to heartworm disease in Europe in the last 10 years? (2022) · cites this paper as [13]

  • According to Vieira et al., canine heartworm prevalence in the centre and northeast of Portugal was 2.1%.

    “According to Vieira et al. [13], the prevalence in the centre and northeast of the country was 2.1%.”

    From What has happened to heartworm disease in Europe in the last 10 years? (2022) · cites this paper as [13]

  • In Portugal, feline prevalence studies demonstrate important presence of D. immitis in cats, with seroprevalence of 15% in centre Portugal in 2009-2010, highest seroprevalences in Aveiro and Viseu (18.7 and 17.6%), 4.8% in southern Portugal, and 3.5% on Madeira.

    “In Portugal, feline prevalence studies are relatively recent, but demonstrate the important presence of this parasite in the cats living in the country. The seroprevalence of samples collected in the centre of Portugal in 2009 and 2010 was 15% [13], the highest feline seroprevalences being found in Aveiro and Viseu (18.7 and 17.6%, respectively). Later, Maia et al. [121] reported a prevalence of 4”

    From What has happened to heartworm disease in Europe in the last 10 years? (2022) · cites this paper as [13]

  • Canine dirofilariosis due to D. immitis is known to be endemic and widely distributed in Portugal, with prevalence ranging between 0.9 and 27.3% in mainland regions to over 30% in Madeira Island.

    “Canine dirofilariosis due to D. immitis is known to be endemic and widely distributed in Portugal, with prevalence ranging between 0.9 and 27.3% in mainland regions to over 30% in Madeira Island [22–25]”

    From Molecular characterization of Dirofilaria spp. circulating in Portugal (2017) · cites this paper as [23]

Cites

Flagged first, then by citations

Research works printed but not linked: 15

  1. Araújo, 1996, Parassitologia, 38, 366
  2. Bargues M. 2009. Culicid vector characterization by means of molecular haplotyping, in Proceedings of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 116–123.
  3. Cancrini G, Gabrielle S. 2009. Global warming: effects on abundance and distribution of Dirofilaria natural vectors, in Proceedings of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 98–106.
  4. Datz, 2003, Compendium, 25, 30
  5. Genchi C, Guerrero J, McCall J, Venco L. 2007. Epidemiology and prevention of Dirofilaria infection in dogs and cat, in Proceedings of First European Dirofilaria Days, 22–25 February. Genchi C, Rinaldi L, Cringoli G, Eds. Zagreb, Croatia. p. 145–162.
  6. Hoch, 2008, Compendium Continuing Education Veterinary, 30, 133
  7. Leidy, 1856, Proceeding of the Academy of Natural Sciences of Philadelphia, 8, 2
  8. McCall J. 2009. Update American Heartworm Society Canine guidelines, with emphasis on the role of doxycycline in adulticidal therapy, in Proceeding of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 44–166.
  9. McCall J, Genchi C, Kramer L, Guerrero J, Dzimianski M, Mansour A, McCall S, Grandi G, Carson B. 2012. Role of doxycycline treatment in preventing heartworm disease, killing adult heartworms and blocking heartworm transmission, in Proceeding of Third European Dirofilaria Days, 21–22 June. Genchi G, Kramer L, Genchi C, Eds. Parma, Italy. p. 25.
  10. Morchón R, Simón F, González-Miguel J, Mellado I. 2009. Relationship Dirofilaria /hosts: cellular and molecular mechanisms of the heartworm disease vascular pathology, in Proceedings of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 116–123.
  11. Osório, 2010, European Mosquito Bulletin, 28, 187
  12. Ribeiro, 1983, Jornal da Sociedade de Ciências Médicas de Lisboa, 147, 143
  13. Schrey, 1998, Waltham Focus, 8, 23
  14. Símon F, Gonzalez-Miguel P, Kartashev V, Morchon R, Carretón E, Montoya-Alonso J. 2012. Human dirofilariosis: what is changing?, in Proceeding of Third European Dirofilaria Days, 21–22 June. Genchi G, Kramer L, Genchi C, Eds. Parma, Italy. p. 22–23.
  15. Venco L. 2009. New insight into heartworm disease management: from old legends to the present looking to the future, in Proceeding of Second European Dirofilaria Days, 16–18 September. Morchón R, Simón F, Montoya JA, Genchi C, Eds. Salamanca, Spain. p. 107–115.

Cited by

Sorted by citations

Related

Authors
Vieira, A. L., Vieira, M. J., Oliveira, J. M., Simões, A. R., Diez-Baños, P., & Gestal, J.
Affiliations
  • Escola Universitária Vasco da Gama (PT)
  • Universidade de Santiago de Compostela (ES)
Corresponding author
Vieira, Ana Luísa
ORCID
Venue
Parasite
Publisher
EDP Sciences
Published
2014
Volume
21
Pages
5
ISSN
  • 1252-607X (ISSN-L)
  • 1776-1042
DOI
10.1051/parasite/2014003
PMC
PMC3927308
OpenAlex
W2158274215
Cited by
53
References
38
Citations by year
2026: 5 · 2025: 1 · 2024: 5 · 2023: 7 · 2022: 7 · 2021: 6 · 2020: 7 · 2019: 4 · 2018: 3 · 2017: 1 · 2016: 5 · 2015: 2
FWCI
1.87
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Parasite (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, other-oa)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, cc-by)
  • LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, other-oa)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Hispana (submittedVersion, cc-by)
  • Repositorio institucional da Universidade de Santiago de Compostela (University of Santiago de Compostela) (submittedVersion, other-oa)
  • RUNA. Repositorio Institucional del Sergas (Servicio Gallego de Salud (SERGAS)) (submittedVersion, other-oa)
Funders
Fundação para a Ciência e a Tecnologia (/2009)
Topics
  • Health Sciences › Medicine › Infectious Diseases › Parasitic Diseases Research and Treatment
  • Health Sciences › Veterinary › Small Animals › Helminth infection and control
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Research on Leishmaniasis Studies
Keywords
canine heartworm disease, Dirofilaria immitis, prevalence, risk factors, dogs, microfilaremia, occult infection, acid phosphatase staining, Figueira da Foz, Central Portugal, rural dogs, large breed dogs, disease screening
MeSH terms
Animals, Dirofilaria immitis, Dirofilariasis, Disease Reservoirs, Dog Diseases, Dogs, Female, Insect Vectors, Male, Microfilariae, Models, Biological, Culicidae, Portugal, Risk Factors, Rural Health, Seasons, Urban Health, Prevalence, Parasitemia

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review