Contact with pigs and cats associated with high prevalence of Toxoplasma antibodies among farmers.

Abstract

Antibodies to Toxoplasma were measured by enzyme linked immunosorbent assay (ELISA) in sera from 159 abattoir workers, 142 pig farmers, and 106 grain or berry farmers. Farmers occupationally exposed to pigs had antibodies in 53 (37%) cases, abattoir workers in 40 (25%) cases, and farmers not exposed to pigs in 24 (23%) cases. In each group antibodies were more prevalent among those who had a cat or cats in the household. Controlling for age and cat contacts changed the prevalences less than one percent. The results indicate that pig farmers might have an occupational risk of toxoplasmosis. As the prevalence of antibodies among abattoir workers was about the same as among the referent farmers, it seems unlikely that infection from Toxoplasma could be acquired by mere handling of raw meat.The Toxoplasma parasite infects many animal species. In humans, the infection is usually subclinical and in symptomatic cases the diagnosis is often missed.' After the primary infection, viable Toxoplasma cysts probably persist throughout life.2 Toxoplasma has a worldwide distribution. The prevalence of infection among adults varies greatly in different populations; up to 90% are infected in Paris and up to 50% in the United States.3 Humans are known to be infected by at least three routes: transplacental infection in congenital transmission,4 infection by the cyst through ingestion of raw meat,5 6 and infection by the oocyst from contact with infected cats or exposure to contaminated soil.' 78 Routes of infection may vary, depending on hygienic and social factors, on humidity, and on occupations, manners, and customs of inhabitants.9 10Although cats are considered to play a central part in the spreading of toxoplasmosis,'178 11 several epidemiological studies,9 1217 including some in Scandinavia,'>20 have failed to show increased prevalence of antibodies among those in contact with cats.Toxoplasma infection is highly prevalent in swine in many countries,21, but the prevalence ofantibodies to Toxoplasma in slaughtered pigs in Finland is only about 2-5% as measured by ELISA.22 We studied the prevalence of antibodies to Toxoplasma among pig farmers, grain or berry raising farmers, and abattoir workers to find possible associations with cat and pig contacts. Materials and methodsWorkers from the killing floor of six pig processing abattoirs situated in central and northern Finland were asked to participate. In today's Finnish abattoirs these workers use bare hands in contact with the flesh of the carcasses. For the sake of hygiene the use of gloves, customary for other jobs in meat processing plants, is forbidden in work on the killing floor. A total of 177 workers were asked to fill in a questionnaire and to give a blood sample for antibody testing; 159 (90%) blood samples were obtained from the abattoir workers.Similar questions were sent to 270 pig farmers and 310 farmers whose first or second line of production was either grain or berry raising. The grain or berry farmers were not involved in meat production and live...

Spontaneous abortions among veterinarians

“…Colnparisons of the prevalence of antibodies to toxoplasma among veterinarians and other workers have not suggested an increased risk, however, except for veterinarians in large-animal practice (13). They may have an increased risk through mucous membrane contact with blood or the excretions of infected animals, while helping with labor and while making field autopsies (14).…”

Risk factors for infection with Toxoplasma gondii for residents and workers on swine farms in Illinois.

“…Exposure to cats and cat feces has been considered a major risk factor for acquisition of infection. However, while several studies have concluded that exposure to cats increased the risk of T. gondii seropositivity, [19][20][21][22][23][24][25][26] other studies found no association, [27][28][29][30][31][32][33][34] and one study 35 found that possession of cats decreased this risk. Exposure to cats is not sufficient for transmission of T. gondii infection to humans; infection in cats and personal hygiene should also be evaluated.…”

“…Whereas contact with soil and gardening have been implicated as risk factors for T. gondii seropositivity, 19,26 several studies have found no association between soil contact and seropositivity. 25,34 The role of handling or consumption of raw meat in the acquisition of T. gondii infection has not always been clear. Several studies have found no association, 21,25,28,33 although some studies have identified an association between eating raw meat and T. gondii seropositivity, 32,34 and handling of raw organ meats used for pet food has been identified to increase the risk of T. gondii infection in men.…”

“…25,34 The role of handling or consumption of raw meat in the acquisition of T. gondii infection has not always been clear. Several studies have found no association, 21,25,28,33 although some studies have identified an association between eating raw meat and T. gondii seropositivity, 32,34 and handling of raw organ meats used for pet food has been identified to increase the risk of T. gondii infection in men. 20 The seroprevalence for T. gondii increases with age, 21,28,32,33,35 presumably due to accumulated opportunities for exposure.…”

“…Numerous studies have found no sex differences in T. gondii seroprevalence, 21,28,33,34 although one study found a higher seroprevalence in male farmers in Japan, and attributed this to more consumption of raw meat. 32 Rural rearing, 4,19,36,37 exposure to farm animals, 19,35 and rearing of pigs 25 have been identified as increasing the risk of human seropositivity. Two epidemiologic investigations have identified a high seroprevalence of T. gondii infection in cats inhabiting swine farms: 42% and 67%, 38,39 and infection in cats has been implicated as a risk factor for T. gondii infection in pigs.…”