Heartworm infection in domestic dogs in Canada, 1977-2016: Prevalence, time trend, and efficacy of prophylaxis.

Dirofilaria immitis (heartworm) is a mosquito-borne parasite that primarily infects domestic and wild canids. The objectives of this study were to i) determine if there has been a temporal change in prevalence of heartworm infection among domestic dogs in Canada from 1977 to 2016; ii) explore the spatial extension of heartworm across Canada using choropleth maps; and iii) assess the efficacy of preventive drugs using the estimated "Attributable Fraction Exposed." Heartworm surveys that collected data from 1977 to 2010 and serological laboratory data from 2007 to 2016 were analyzed. The data depicted a decrease in heartworm prevalence, both nationally and provincially, from 1977 to the early 2000s. However, an increase in prevalence was identified for tested dog populations in Manitoba and Quebec from 2007 to 2016. Chemoprophylaxis was associated with an estimated 93.0% [95% confidence interval (CI): 92.85, 93.3] reduction of heartworm infections in domestic dogs in Canada from 1977 to 2010.

[1]  S. Hewitt,et al.  2017 , 2017, Les 25 ans de l’OMC: Une rétrospective en photos.

[2]  Robert B. Lund,et al.  Forecasting United States heartworm Dirofilaria immitis prevalence in dogs , 2016, Parasites & Vectors.

[3]  Katherine E. Bishop-Williams,et al.  Mapping rural community and dairy cow heat stress in Southern Ontario: A common geographic pattern from 2010 to 2012 , 2016, Archives of environmental & occupational health.

[4]  D. Stone,et al.  A Survey of Canine Heartworm Awareness in Grenada, West Indies , 2015, Journal of applied animal welfare science : JAAWS.

[5]  J. Diaz,et al.  Risk factors for human heartworm infections (dirofilariasis) in the South. , 2015, The Journal of the Louisiana State Medical Society : official organ of the Louisiana State Medical Society.

[6]  A. Daugschies,et al.  Climate suitability for the transmission of Dirofilaria immitis and D. repens in Germany. , 2014, Veterinary parasitology.

[7]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[8]  Chetan Tiwari,et al.  Five Essential Properties of Disease Maps , 2012 .

[9]  J. Lachin.  Power and sample size evaluation for the Cochran–Mantel–Haenszel mean score (Wilcoxon rank sum) test and the Cochran–Armitage test for trend , 2011, Statistics in medicine.

[10]  C. Genchi,et al.  Dirofilarial infections in Europe. , 2011, Vector borne and zoonotic diseases.

[11]  S. Martin,et al.  Veterinary Epidemiologic Research , 2009 .

[12]  Olaf Berke,et al.  Exploratory disease mapping: kriging the spatial risk function from regional count data , 2004 .

[13]  Olaf Berke,et al.  Choropleth mapping of regional count data of Echinococcus multilocularis among red foxes in Lower Saxony, Germany. , 2001, Preventive veterinary medicine.

[14]  S. Martin,et al.  Canine heartworm testing in Canada: are we being effective? , 2000, The Canadian veterinary journal = La revue veterinaire canadienne.

[15]  I. Dohoo.  Application of Quantitative Methods in Veterinary Epidemiology , 1998 .

[16]  D. Rizzo,et al.  Canine Heartworm Disease , 1989 .

[17]  J. Fortin,et al.  Temperature requirements for the development of Dirofilaria immitis in Aedes triseriatus and Ae. vexans. , 1981 .

[18]  J. Slocombe.  Heartworm in dogs in Canada in 1977. , 1978, The Canadian veterinary journal = La revue veterinaire canadienne.

[19]  B. Gladen,et al.  Estimating prevalence from the results of a screening test. , 1978, American journal of epidemiology.