AHS releases new heartworm incidence survey results

The American Heartworm Society (AHS) has announced the results of its 2019 Heartworm Incidence Survey, and its conclusions are clear: The “big picture” of heartworm disease in the United States hasn’t changed, and preventive pet care remains vital even amid the public health crisis facing the country.

AHS conducts its nationwide heartworm incidence survey every three years, using data from animals tested over the previous 12 months. Nearly 6,000 U.S. veterinary practices and shelters participated in the 2019 survey, amounting to more than 5.5 million heartworm tests. Those data were used to compile a new heartworm incidence map depicting the locations and prevalence of heartworm disease throughout the country in 2019.

No state was heartworm-free, according to this year’s findings, but some stood out among the rest. The five states with the highest heartworm incidence in 2019—all of which have been in the top tier since the AHS began tracking data in 2001—were Mississippi, Louisiana, South Carolina, Arkansas and Alabama.

“When veterinarians compare the 2016 heartworm incidence map to the 2019 map, it’s clear that the big picture hasn’t changed,” AHS President Chris Duke, DVM, says in an announcement on the AHS website. “The Southeast remains a hotbed for heartworm infection, but states in the Northeast, Midwest, and West have continued to see many cases as well.” Those states include Texas, Tennessee, Georgia, North Carolina and Oklahoma, which round out the top 10 states for the highest heartworm incidence.

The survey also polled veterinarians for their opinions on trends noted in the previous three years. Here’s what they found:

• 11% of surveyed veterinary practices and shelters reported no heartworm cases, compared with 13% three years ago.
• 26% of practices and shelters said they saw an upward trend in heartworm incidence, while 16% noted a downward trend and 57% of saw no change.
• Those who reported an upward trend were most likely to cite “an influx of heartworm-positive patients into their practice area” and “poor compliance” as the causes.
• Those who noted a decrease in heartworm incidence cited “improved preventive compliance among users” and “more owners giving heartworm preventives.”
• 82% of survey respondents said they follow AHS guidelines on heartworm prevention, testing and treatment.

While the spread of COVID-19 has limited the ability of veterinary practices to conduct routine patient health screenings, the AHS stresses that this should not mean lapses in heartworm preventive administration.

“The need for heartworm prevention is more important than ever,” Dr. Duke says. “Prevention continues to be one of the most important recommendations veterinary practitioners can recommend for patient care, and avoiding gaps in year-round prevention is essential.”