New Jersey Department of Agriculture

Memo

To: Veterinarians

From: Nancy E. Halpern, D. V. M. State Veterinarian

Date: September 25, 2007

Re: Case of Screwworm in Mississippi

As APHIS VS has determined that larvae found in a canine patient in Kiln, Mississippi, have been identified as screwworm. Screwworm is considered a foreign animal disease (FAD). The United States officially eradicated the screwworm in 1982 using the sterile insect technique.

Kiln is approximately 20 miles west of Gulfport, Mississippi and close to the Gulf Coast. The dog was imported from Trinidad and entered the country through the Miami airport on Thursday, September 13. The dog was in Miami for approximately 4 hours and the dog stayed in its carrier in the car during this time. The dog was then taken by car to Mississippi. On September 16th, the 16-year old dog was presented to the Picayune Animal Clinic with bilateral globe rupture as a result of the larval infection. Both eyes and approximately 20 larvae were surgically removed. The Mississippi State Veterinarian was contacted and three larvae were submitted to NVSL for identification, which were identified as larval screwworm, Cochliomyia hominivorax. The animal has been isolated to the owner's home since September 18. A verbal quarantine was initiated by the State Veterinarian on September 20 at 3:00 p.m. and remains in effect.

VS is conducting an epidemiological investigation and working closely with Mississippi on this investigation. APHIS VS has notified OIE of the detection.

A screwworm infestation is caused by larvae of the fly Cochliomyia hominovirax. These larvae can infest wounds of any warm-blooded animal, including human beings. Additionally the adult females may lay eggs near the nostrils of all warm blooded animals, where they hatch and nearly invisible larvae migrate into the nasal passages and feed on living tissue throughout the head, including the brain. The screwworm fly is about twice the size of a regular house fly and can be distinguished by its greenish-blue color and its large reddish-orange eyes. Infestations can occur in any open wound, including cuts, castration wounds, navels of newborn animals, and tick bites. The wounds often contain a dark, foul-smelling discharge. Screwworm larvae distinguish themselves from other species by feeding only on the living flesh, never dead tissue. Once a wound is infested, the screwworm can eventually kill the animal or human, literally eating it alive.

All animal owners and workers should be aware of the possibility of screwworm infestation in their animals. Any foul smelling wound oozing a dark liquid which contain fly larvae should suggest a screwworm problem. These wounds should be quickly brought to the attention of their veterinarian so that suspected larvae can be collected and submitted to the New Jersey Department of Agriculture Animal Health Laboratory. Larvae can be placed in a container with 70% alcohol to preserve them for identification.

If you have a suspect case of screwworm, please contact the Division of Animal Health at (609) 292-3965. By quickly identifying any screwworm larvae, appropriate steps can be taken to prevent a return to the 1950's and the enormous losses which the livestock industry sustained due to screwworm infestations.