{"id":22157,"date":"2020-10-05T18:06:06","date_gmt":"2020-10-05T18:06:06","guid":{"rendered":"https:\/\/todaysveterinarypractice.com\/?p=22157"},"modified":"2022-04-05T15:29:07","modified_gmt":"2022-04-05T15:29:07","slug":"the-state-of-heartworm-incidence-in-the-united-states","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/parasitology\/the-state-of-heartworm-incidence-in-the-united-states\/","title":{"rendered":"The State of Heartworm Incidence in the U.S."},"content":{"rendered":"

Changes in weather patterns. Lapses in preventive medication compliance. Pet relocation. These factors and more were cited in a recent survey of U.S. veterinarians as factors contributing to the rise and fall of heartworm incidence in their practice areas.<\/span><\/p>\n

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The Heartworm Hotline<\/b> column is presented in partnership between Today\u2019s Veterinary Practice<\/i><\/b> and the American Heartworm Society<\/b> (heartwormsociety.org<\/span><\/a>). The goal of the column is to communicate practical and timely information on prevention, diagnosis, and treatment of heartworm disease, as well as highlight current topics related to heartworm research and findings in veterinary medicine.<\/span><\/p>\n

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To help veterinary professionals, shelter personnel, and pet owners understand heartworm trends in their areas, the American Heartworm Society (AHS) began tracking U.S. heartworm incidence in January 2002. Since then, the AHS Heartworm Incidence Survey has been conducted every 3 years, using heartworm testing data submitted by veterinary practices, reference laboratories, and animal shelters. Following the analysis of survey results, a U.S. heartworm incidence map is generated to provide a visual representation of the spread and severity of heartworm infections.<\/span><\/p>\n

The AHS released the results of the most recent survey, which reflects testing results from the 2019 calendar year. Just under 6000 veterinary practices and shelters submitted data from more than 5.5 million pets. The 2019 map (<\/span>FIGURE 1<\/b><\/span>) was unveiled in April 2020.<\/span><\/p>\n

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Figure 1. Heartworm incidence in the continental U.S. and Hawaii based on the 2019 AHS Heartworm Incidence Survey. Courtesy American Heartworm Society.<\/p><\/div>\n

How Many Pets in the U.S. Are Heartworm-Positive?<\/h2>\n

While it is possible to use the survey data to make rough projections regarding heartworm prevalence, it is impossible to know exactly how many pets in the U.S. are infected with heartworms at any given time. An important factor is that heartworm diagnosis requires one or more blood tests that must be conducted in a veterinary clinic and\/or reference laboratory, which limits diagnoses to patients seen in clinics and animal shelters. Dogs and cats not seen by veterinarians and\/or not tested for heartworms during annual veterinary visits may be infected but go unrecognized for years. Unfortunately, the lack of veterinary care translates to a lack of heartworm prevention, and these pets are among those most likely to be positive, infecting mosquitoes and other dogs in the neighborhood.<\/span><\/p>\n

While acknowledging these important caveats, the AHS hypothesized a conservative estimate of heartworm prevalence via the following calculations:<\/span><\/p>\n