Equine dermatitis outbreak associated with parapoxvirus.

Parapoxviruses (PPV) cause skin and mucous membrane lesions in several animal species, and of the five recognized PPVs, at least three are zoonotic. Equine PPV (EqPPV) is the sixth one initially described in humans in the United States and later in a severely sick horse in Finland in 2013-2015. In 2021-2022, a large-scale pustulo-vesicular pastern dermatitis outbreak occurred in horses all over Finland. This study aimed at analysing the outbreak, identifying and describing the causative agent, describing clinical signs, and searching for risk factors. EqPPV was identified as a probable causative agent and co-infections with several potentially pathogenic and zoonotic bacteria were observed. Histopathologically, suppurative and ulcerative dermatitis was diagnosed. Due to the lack of specific tests for this virus, we developed a novel diagnostic EqPPV-PCR with sensitivity of 10 copies/reaction. Based on a large proportion of the genome sequenced directly from clinical samples, very little variation was detected between the sequences of the case from 2013 and the cases from 2021 to 2022. Based on an epidemiological survey, the main risk factor for pastern dermatitis was having racehorses. Approximately one third of the horses at each affected stable got clinical dermatitis, manifesting as severe skin lesions. Skin lesions were also occasionally reported in humans, indicating potential zoonotic transmission. Case stables commonly reported attendance at race events before acquiring the disease. Survey also identified differences in practises between case and control stables. Taken together, these results enable a better preparedness, diagnostics, and guidelines for future outbreaks.

No Substantial Histopathologic Changes in Mops condylurus Bats Naturally Infected with Bombali Virus, Kenya.

We found similar mild perivascular inflammation in lungs of Bombali virus-positive and -negative Mops condylurus bats in Kenya, indicating the virus is well-tolerated. Our findings indicate M. condylurus bats may be a reservoir host for Bombali virus. Increased surveillance of these bats will be important to reduce potential virus spread.

Sarcocystis calchasi in a captive Patagonian conure (Cyanoliseus patagonus) in Finland.

Sarcosystis calchasi is an emerging pathogen causing encephalitis in many avian species and has been documented in North America, Germany and Japan. In November 2019, a captive Patagonian conure (Cyanoliseus patagonus), kept in a zoological aviary in Finland, was euthanized due to acute respiratory distress. At necropsy, histopathological examination revealed numerous parasitic tissue cysts in the skeletal muscles and myocardium, chronic moderate multifocal lymphoplasmacytic and histiocytic meningoencephalitis and acute moderate multifocal purulent pneumonia caused by aspiration of foreign material. By light and transmission electron microscopy, tissue cysts had structures typical of Sarcocystis organisms. The ultrastructure of the cyst wall was compatible with S. calchasi and Sarcocystis columbae. S. calchasi-specific semi-nested polymerase chain reaction testing resulted in amplification of the internal transcribed spacer (ITS) gene, which had 100% identity with S. calchasi ITS sequences. This is the first report of S. calchasi in Fennoscandia and of a naturally-occurring S. calchasi infection in a captive psittacine bird in Europe. Our finding suggests that captive psittacine birds kept in outdoor facilities may be at risk of S. calchasi infection throughout the Holarctic.

Severe Spontaneous Atherosclerosis in two Korat Breed Cats is Comparable to Human Atherosclerosis.

Atherosclerosis is a chronic inflammatory vascular disease and the leading cause of mortality in humans worldwide. In most domestic animal species, however, primary atherosclerosis is of little clinical relevance. Cats are considered to be atheroresistant and, to our knowledge, spontaneous atherosclerosis has not been reported in cats. Here we report the clinical and histopathological findings in two related cats of the Korat breed that presented with clinical signs of heart failure. In both cases, the clinical signs appeared in adulthood, were progressive and led to death. At necropsy, severe atherosclerotic lesions were present in large and medium-sized arteries and were characterized by the formation of a fibrous cap and a lipid core, which contained a particularly large accumulation of cholesterol crystals, as indicated by the presence of many cholesterol clefts. The lesions closely resembled those of advanced human atherosclerosis. There were no underlying diseases or medical treatments that could have predisposed to the atherosclerosis in these two genetically related cats. A genetic predisposition to human-like atherosclerosis in the local Korat cat population is suspected.

Infection with Possible Novel Parapoxvirus in Horse, Finland, 2013.

A horse in Finland exhibited generalized granulomatous inflammation and severe proliferative dermatitis. After euthanization, we detected poxvirus DNA from a skin lesion sample. The virus sequence grouped with parapoxviruses, closely resembling a novel poxvirus detected in humans in the United States after horse contact. Our findings indicate horses may be a reservoir for zoonotic parapoxvirus.

Early Trichinella spiralis and Trichinella nativa infections induce similar gene expression profiles in rat jejunal mucosa.

Trichinella spiralis causes a significantly higher parasite burden in rat muscle than Trichinella nativa. To assess whether the difference in infectivity is due to the early intestinal response, we analyzed gene expression changes in the rat jejunum during Trichinella infection with a whole-genome microarray. The rats were euthanized on day five of infection, and their jejunal mucosa was sampled for microarray analysis. In addition, intestinal histology and hematology were examined. Against our expectations, the gene expression changes were similar in both T.nativa- and T. spiralis-infected groups. The two groups were hence pooled, and in the combined Trichinella-infected group, 551 genes were overexpressed and 427 underexpressed when compared to controls (false discovery rate ≤ 0.001 and fold change at least 2 in either direction). Pathway analysis identified seven pathways significantly associated with Trichinella infection (p < 0.05). The microarray data suggested nonspecific damage and an inflammatory response in the jejunal mucosa. Histological findings, including hyperemia, hemorrhage and a marked infiltration of inflammatory cells, supported the microarray data. Trichinella infection caused complex gene expression changes that indicate a host response to tissue damage in the mucosa of the jejunum, but the changes were not notably dependent on the studied species of Trichinella.

The different infectivity of Trichinella spiralis and Trichinella nativa in rat does not solely localize to enteral or parenteral phase.

Rats are selective hosts for Trichinella nativa; infection levels in their muscles remain low when compared to Trichinella spiralis. To identify in which phase of the life cycle the selective responses take place, rats were infected perorally (p.o.) and intravenously (i.v.) with T. spiralis and T. nativa. Six rats were placed in each group; three rats served as uninfected controls. The infection intensities were examined 5 or 6 weeks after the infection. T. spiralis muscle larva burden was 57 times higher compared to that of T. nativa after p.o. inoculation (mean larvae per gram ± SD, 1,243 ± 378.9 vs. 22 ± 21.5). In i.v. inoculation, 12 times more T. spiralis larvae reached the muscle than with T. nativa. Also, in vitro newborn larva (NBL) production at day 6 postinfection was analyzed for parasites originating from both rat and mouse. The mean number of in vitro-produced NBL of rat-origin T. spiralis during 24 h was 70 (95 % CI, 65-75) and of T. nativa, 23 (95 % CI, 21-24). Intriguingly, this difference was less obvious with mouse-origin female Trichinella. NBL production of mouse origin T. spiralis was 57 (95 % CI, 51-62) and T. nativa, 29 (95 % CI, 26-31). Intestine histology at day 40 post p.o. infection, serological response, and weight dynamics were indistinguishable between the Trichinella species but differed from controls. Our results show that the defense against T. nativa is not solely enteral in rats but may partly be explained by different reproduction processes for the two Trichinella species in rat.

Sylvatic Trichinella spp. infection in Finland.

Although human infections caused by Trichinella sp. have not been reported in Finland for several decades and Trichinella sp. infection in pork has become virtually extinct in the last decade, sylvatic Trichinella spp. infection is still highly prevalent in Finland. Muscle digestion of 2,483 carnivorous wild animals from 9 host species during 1999-2005 showed 617 positive animals (24.8%). Molecular identification from 328 larval isolates revealed 4 different endemic Trichinella species, i.e., T. nativa, T. spiralis, T. britovi, and T. pseudospiralis. Seven percent of the infected animals carried mixed infections. Trichinella nativa was the most common species (74%), but T. spiralis was identified in 12%, T. britovi in 6%, and T. pseudospiralis in 1% of the animals. Host species showed different sample prevalence and Trichinella species distribution. Geographical distribution also varied, with the southern part of the country having significantly higher percentages than the northern part. Infection density was dependent on both the infecting Trichinella species and the host species. Trichinella spiralis was discovered in areas with no known domestic infection cases, indicating that it can also occur in the sylvatic cycle. Raccoon dogs and red foxes are the most important reservoir animals for T. spiralis , as well as for the sylvatic Trichinella species in Finland.

A nonhealing ulcerative skin lesion associated with Trichinella nativa infection in a cat.

Trichinella spp. can infect various domestic and wild species, including companion animals. Infection occurs because of the ingestion of raw meat (e.g., infected prey). In experimental studies, cats have been found to be a very susceptible host to infection by Trichinella spp.; naturally occurring feline infections have also been reported. However, clinically apparent disease seems to be a rare manifestation of this infection in cats. The skin biopsy of an 8-year-old, neutered, male, domestic cat revealed an inflammatory granulation tissue that surrounded a well-preserved cyst that contained a Trichinella sp. larva. Distinct seropositive reaction against Trichinella spp. antigens was demonstrated by enzyme-linked immunosorbent assay and Western blot. Immunohistochemistry, by using serum from the infected cat as the source of antibody, showed strong immunostaining of Trichinella spp. larvae. During a 1-year follow-up, a postexcisional local tissue reaction was observed. This manifested as a firm, poorly circumscribed subcutaneous mass adjacent to the eye, which demonstrated clinical features and histopathologic findings indicative of chronic inflammation associated with granulation tissue and fibrodysplasia. Digestion of the muscle biopsy revealed one Trichinella sp. larva, which was identified by multiplex polymerase chain reaction as Trichinella nativa. To the authors' knowledge, this is the first documented case of trichinellosis in a cat with a nonhealing ulcerative skin lesion as the main clinical manifestation of the infection.