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The parasite Toxoplasma gondii IS capable of infecting most mammals 1ncluding man. In humans, toxoplasmosis 1s usually asymptomatic but may have serious consequences for pregnant women or immuno-comprom1sed patients. Contact with infected cats and cat litter, contaminated soil and Infected meat are risk factors for toxoplasmosis. Although the prevalence of Toxoplasma in pig production has declined significantly dunng the past 30 years, it has recently been suggested that a large part of human cases of toxoplasmosis may be ascribed to meat, mcluding pork and pork products. Moreover, perinatal screening of pregnant women and infants for Toxoplasma has proven to be of limited value. This has ra1sed the question of how to survey for Toxoplasma· in humans or meat? Therefore, the role of meat, including pigs and pork, as a risk factor for human toxoplasmosis was assessed by the Danish Meat Association . The release assessment showed that outdoor-reared p1gs as well as sows and boars were at higher risk of infection with Toxoplasma. With respect to exposure, consumption of mildly cured pork products and inadequately heat-treated pork were associated with increased nsk. Knowledge on elimination or surv1val of Toxoplasma in cured pork products IS sparse, wh1ch IS unsatisfactory g1ven current trends toward lower salt content and lower cooking temperatures. It was concluded that, aside from consumption of raw pork, wh1ch IS rare in Denmark and not recommended for other reasons, certain m1ldly cured ready-to-eat pork products, that have not been heat-treated, may const1tute a nsk for toxoplasmosis, if not frozen prior to manufacturing. Information on the effects of cunng on surv1val of Toxoplasma in meat is sparse and therefore deserves further research. However, most of the pork used for manufacturing m Denmark onginates from p1gs ra1sed mdoors and for log1st1c reasons it is frozen prior to processmg, thereby reducing the risk for human toxoplasmosis. Introduction Toxoplasma gondit IS a ubiquitous protozoan parasite that can infect most mammals, including man. The mam sources of infect1on for humans are contact w1th Infected cats or cat litter, contaminated so1l or ingestion of undercooked infected meat. The prevalence of Toxoplasma in pig production has declined s1gmficantly during the past 30 years, and especially in finisher pigs ra1sed Indoors seroprevalences are now typically below 5% (see Tenter et al. , 2000, for review) Th1s decline is mainly attributed to more intensive housmg systems especially m Europe and hence reduced exposure to Toxoplasma from cats and the environment (Tenter et al. , 2000). However, recently a European mult1-centre study on Toxoplasma has suggested that 30-60% of human cases of toxoplasmosis may li.le ascribed to meat, including pork and pork products, albeit with substantial variation between centres as regards the type of meat involved (Cook et al , 2000). Other studies have also md1cated an assoc1at1on between the risk of acquiring Toxoplasma and consumption of undercooked pork or certain cured pork products (e g Buffolano et al , 1996, Kapperud et al. , 1996). However, the question remains what is the role of meat, and m part1cular pork, for human toxoplasmosis? To address this quest1on, a risk assessment was conducted by the Damsh Meat Association . The aim was to assess the nsk for human toxoplasmosis assoc1ated with pork and pork products. The nsk assessment followed the guidelines 1ssued by Codex Alimentanus and OlE and contained the following steps. Ses 10n 3· V•rusos. parasites, other pathogens Safepork 2007Verona (Italy) 195 • Hazard Identification • Release assessment • Exposure assessment • Consequence assessment • Risk estimation Finally, we provide some suggestions for risk management. Hazard identification Toxoplasma is, amongst others, a meat-borne infection that can cause serious disease 1n unborn children or immuno-suppressed patients. Like in many other European countries w1th Intensive p1g production, Toxoplasma is found at a low prevalence (3%) in Damsh fimsher pigs (Lmd et al., 1994). However, it cannot be excluded that some cases of human toxoplasmosis in Denmark can be ascribed to pork. Therefore, Toxoplasma was considered a relevant hazard. Release assessment To date, serology is the qu1ckest and most-often used method of testing p1gs for Toxoplasma, being a good ind1cator for the burden of Toxoplasma in a p1g (Dubey et al. , 1995). Toxoplasma seroprevalence in pigs in Europe is generally low (i.e. $5%) in finisher p1gs that are ra1sed indoors. Higher prevalences have been found in outdoor-reared pigs (Fehlhaber et al., 2003; Kijlstra et al., 2004; Venturini et al., 2004), and the highest prevalences are found 1n sows and boars (Tenter et al, 2000). Exposure assessment Due to expens1ve bioassay methods and not yet validated DNA methods, only limited data ex1st on occurrence of Toxoplasma 1n raw, unprocessed pork. Evidence stems largely from human casecontrol studies showing that toxoplasmosis m1ght be associated with, amongst others, consumption of raw pork (e.g. Cook et al., 2000). In a recent comprehensive study, Dubey et al. (2005) found Toxoplasma 1n 0.4% of 2,094 fresh pork samples purchased in reta1l outlets 1n the US. Toxoplasma in pork will survive refrigeration at 4°C but not at ooc (Hill et al., 2006). Toxoplasma does not mult1ply in fresh or refngerated meat. Processing methods with a well-documented effect of elimmat1ng Toxoplasma in meat are freezing and heat-treatment (cook1ng, fry1ng). Freezmg at12°C for 24 hours (e.g. Kotula et al., 1991 ; Smith, 1991 ), or heating to a core temperature of 61 oc for at least 1 m1nute (e.g. Dubey et al. , 1990; Dubey, 2000) will 1nact1vate Toxoplasma In addition, Toxoplasma tissue cysts can be eliminated us1ng radiation techniques (Smith, 2001 ) or highpressure processmg (Lindsay et al. , 2006). In contrast, knowledge on elimination or surv1val of Toxoplasma 1n cured pork products (salted, smoked, dned or fermented meat) IS sparse. Th1s 1s unsatisfactory g1ven current trends toward lower salt content and lower cooking temperatures Among curing procedures, the effect of salting is best-documented Salt concentrations of <::6% eliminate Toxoplasma in pork, whereas Toxoplasma may survive at lower salt concentrations (Dubey, 1997) Cunng of pork lo1ns w1th 2% sod1um chlorate or <::1.4% potass1um or sodium lactate for at least 8 hours prevented transmission to cats (Hill et al , 2004; H1ll et al., 2006). The very few stud1es that looked at survival of Toxoplasma in dried, smoked and/or fermented pork did not detect v1able Toxoplasma (Sommer et al. , 1965, Warnekulasuriya et al., 1998). Consequence assessment Seronegative pregnant women and 1mmuno-compromised patients are the ma1n risk groups for toxoplasmosis Dependmg on the time of infection, congenital Toxoplasma infect1on may result 1n abortions or b1rth of mfants w1th clin1cal s1gns (transmiSSIOn dunng early pregnancy) or birth of Infants with subclinical 1nfect1ons, resulting 1n nervous disorders or eye problems later 1n life (transmiSSion during late pregnancy). Immuno-suppressed patients (e.g AIDS patients) may show severe clinical symptoms such as encephalitis 196 afopork 2007Voronn (Italy) Session 3: V1ruso , par s1tcs, oth r pathogen

Risk assessment for Toxoplasma gondii in the Danish pig industry