Dogs and other animals can transport pests and diseases into the country. In 2007 and 2010, New World screwworm larvae, classified as a foreign pest by USDA, “were found on a dog that had recently entered the United States from Trinidad and Tobago [and] on a dog that traveled from Venezuela to Florida,” respectively.

New World screwworm, described in USDA’s Foreign Animal Disease Preparedness and Response Plan, are:

fly larvae that infest living tissue of warm-blooded animals, causing a condition known as myiasis. Female NWS flies lay their eggs at the edges of wounds or on mucous membranes. The eggs hatch into larvae, burrow into the tissue, and continue to feed and grow. Infestations of NWS can be fatal if untreated.

NWS is currently known to exist in parts of every country in South America except Chile, and in five countries in the Caribbean.

All living warm-blooded animals, including birds, can be infested by NWS, but it occurs most often in mammals (including humans). Unlike many species of blowflies, female NWS flies will only lay eggs on living animals because NWS larvae do not feed on dead tissue or carrion.

In 2007 and 2010 “alert private veterinarian[s] detected the larvae and submitted them to the NVSL for identification.”

The screwworm used to be endemic in the southwestern United States, but were successfully eradicated using sterile insect technology, and considerable cooperative efforts of local governments, states and countries.

According to the Center for Food Security & Public Health, “the NWS likely originated in South America and moved into North America by the early 1800s.”

“The screwworm program [according to USDA] is regarded as one of the most successful animal health eradication efforts in the world . . .ensuring an abundant food supply and saving the meat and dairy industries billions of dollars in lost production. International cooperation and sterile insect technology have been instrumental in pushing the pest as far south as the Darien Gap between Panama and Colombia.”

Dr. Arnold Goldman, DVM, MPH, recently shared the following observation after he diagnosed a different larval fly in a patient in his Connecticut veterinary hospital:

While interstate trafficking in shelter dogs within the continental United States engenders humane, infectious disease and ideological concerns, international and offshore trafficking, as suggested by a recent blog post as a solution to vacant destination state shelter cages, has far more serious infectious disease considerations for the people and animals of our country.

Several foreign animal diseases, diseases present in other nations, continents or islands but not the USA, may be carried by and/or affect dogs and cats, as well as other pet species, and if introduced will have serious animal health, human health and economic consequences to the United States. Please see attached list of “reportable diseases” which USDA accredited veterinarians, i.e. those certified by USDA to assist in disease control and eradication efforts, must be familiar with for these species.

Just last week, I diagnosed a human parasitic fly, Lund’s Fly, in a dog imported from Ghana by a returning government employee (note lumps in image attached). While that fly was not reportable as it was not a “screwworm” which is, the incident illustrates what can happen with uncontrolled, emotionally driven movement of animals across international borders.

Fortunately, USDA recently cracked down on the importation of puppies from other countries under 6 months of age for sale in U.S., but clearly veterinarians should remain vigilant in their examination of their “internationally traveling” patients.

USDA announced a “Save the Date: Screwworm Program Stakeholder Meeting and Workshop Panama City, Panama May 6-8, 2015” for anyone interested in attending.