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From KELOLAND

According to Russ Daly, �ձ�av��Ƶ Extension veterinarian, the New World Screwworm had been in the U.S. in the past, but eradication efforts using sterilized male flies (the females of the species only mate once in their lifecycle) drove the insect out of North America.

But now it is coming back. The NWS has been identified in Mexico and other nations to the south, and Daly speculates that this could be the result of slackening of the use of sterilized males, and perhaps more likely, increased movement of livestock from place to place.

“[The NWS] develops from the fly eggs that are deposited in that animal,” explained Daly. “This particular fly and its eggs, instead of liking the dead tissue (like normal maggots) — it likes the living tissue.”

Daly explained that even something as small as an insect bite on an animal can be enough to attract a fly to lay its eggs.

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Cat Death Losses Due to Highly Pathogenic Avian Influenza in South Dakota

Veterinarians and laboratory diagnosticians are fielding reports of death losses in cat populations linked to avian influenza infections.

Beginning in 2022, an H5N1 subtype of highly pathogenic avian influenza virus caused death losses in domestic turkeys and chickens in South Dakota and elsewhere in the United States, an outbreak that continues. The highly pathogenic avian influenza virus causes respiratory and multiple organ failure in affected birds, typically appearing as increased numbers of dead birds in large commercial operations, as well as smaller backyard flocks. Deaths in wild birds, typically migrating waterfowl but also other bird species, have been observed at the same time, as well as spillover of the virus into mammals, such as raccoons, foxes, skunks and other species.

In spring 2024, the highly pathogenic avian influenza virus began , causing drops in milk production and other signs of illness. Unlike infections in other species, widespread death losses have not been associated with highly pathogenic avian influenza infections in dairy cows.

About the same time as its emergence in dairy cows, the highly pathogenic avian influenza virus was implicated in deaths of domestic cats in the vicinity of affected farms. Most affected cats showed neurologic signs, such as tremors or seizures, for a short period of time before dying.

Since that time, three cases of substantial death losses in groups of outdoor domestic cats in South Dakota have been described. In each of these cases, there has been no apparent link to dairy cows, other livestock or domestic poultry.

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Please note the following changes to the billing for animal rabies testing specimens sent to the South Dakota Animal Disease Research and Diagnostic Laboratory.

Human Exposure to Wildlife

Effective Sept. 1, 2023, South Dakota Game, Fish and Parks will only pay testing fees for wildlife animal species that have posed a risk of human exposure to rabies. This includes live wildlife species that have bitten, scratched or otherwise exposed a person or persons. In the past, this department had paid testing fees for all wildlife species, regardless of human exposure risk.

Human Exposure to Domestic Animals

The South Dakota Department of Health will continue to pay testing fees for domestic animal species that have posed a risk of human exposure to rabies.

Animal-Only or No Exposure

Animal specimens for rabies testing that have exposed other animals or have not exposed either people or animals will be billed to the submitting clinic, regardless of whether the specimen comes from a wildlife or domestic animal species.

Prior to testing, veterinarians and submitters need to fill out the rabies submission form completely and with appropriate detail about human exposures. Information from this form is used to contact people with possible exposures and ensure they get prompt, appropriate treatment should the specimen test positive for rabies. Supplying sufficient detail on the submission form also ensures that testing fees are appropriately charged.

Please call the Animal Disease Research and Diagnostic Laboratory at 605-688-5171 with questions.

To learn more:

As part of an investigation of reproductive losses in an American bison herd, faculty and staff at �ձ�av��Ƶ's Animal Disease Research and Diagnostic Laboratory characterized for the first time persistent infection with Bovine Viral Diarrhea Virus, as well as a novel bosavirus in bison.

Following reproductive problems in a bison herd during the 2018-19 calving season, investigators collected samples from the breeding herd as well as four animals with failure to thrive. Serology, virus isolation, metagenomic sequencing and pathology was performed.

All 26 animals examined serologically had titers to BVDV Type 1 (range 1:512 to 1:8192, with 17 with titers greater than 1:1000) and BVDV Type 2 (range 1:64 to 1:8192, with seven greater than 1:1000), despite the lack of recent BVDV vaccination. Metagenomic sequencing on pooled nasal swabs and serum identified coinfection of BVDV and bovine bosavirus. The BVDV genome was most similar to the BVDV type 1a vaccine strain Oregon C24V with 92.7% identity in the coding region. Bosavirus was also identified but its clinical significance is unknown.

Pathology examination did not reveal any gross lesions. On histopathology, two BVDV-positive animals had lymphoid depletion in the ileocecal valve lymphoid region. A female PI bison had a decrease in primary follicles in the ovary, and a male PI bison showed evidence of decreased spermatogenesis in the testes.

Serum from these same animals collected two months later remained positive for BVDV and bosavirus, with one animal coinfected with both BVDV and bosavirus. These results suggest that both viruses can persistently infect bison. While the etiological significance of bosavirus infection is unknown, the ability of BVDV to persistently infect bison has implications for BVDV control and eradication programs.

Investigators from �ձ�av��Ƶ on the project included Angela Pillatzki, Ben Hause and Chris Chase. They can be contacted at 605-688-5171 for more information.