Veterinary Parasitology, 36
(1990) 343-346
343
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
Short communication
Effect of T e m p e r a t u r e on the I n f e c t i v i t y of Sarcocystis miescheriana Cysts in P o r k A. S A L E Q U E , P.D. J U Y A L a n d B.B. B H A T I A
Department of Parasitology, College of Veterinary Sciences, G.B. Pant University of Agriculture and Technology, Pantnagar-263145 (India) (Accepted for publication 16 January 1990)
ABSTRACT Saleque, A., Juyal, P.D. and Bhatia, B.B., 1990. Effect of temperature on the infectivity of Sarcocystis miescheriana cysts in pork. Vet Parasitol., 36: 343-346.
Sarcocysts of Sarcocystis miescheriana in the thigh muscles of pigs became non-infective to p u p s after heating infected pork in minute pieces at 60 ° C for 20 min, 70 ° C for 15 min and 100 ° C for 5 min. Similar pieces of infected muscle tissues, when exposed to - 4 ° C for 2 days or - 20 ° C for 1 day, became non-infective to pups. The experiment suggests that pork containing sarcocysts of S. miescheriana, and possibly of S. suihominis, requires cooking at a minimum of 70 ° C for 15 min or freezing at - 4 ° C for 2 days or - 20 ° C for 1 day for making it safe for consumption.
INTRODUCTION
The lethal effects of various temperature treatments such as cooking and freezing on the sarcocysts of Sarcocystis cruzi in beef, S. gigantea in mutton and S. levinei in the cardiac tissues of buffaloes have been reported (Fayer, 1975; Golubkov, 1978; Collins and Charleston, 1980; Srivastava et al., 1986). In order to control the transmission of sarcosporidia from intermediate hosts to the definitive hosts, particularly the species of zoonotic importance, i.e.S. hominis and S. suihominis from cattle and swine, respectively, to man, physical applications such as heating and freezing are of great significance. This communication reports the effects of heating, freezing and refrigeration on S. miescheriana from the muscles of local pigs slaughtered for human consumption in the Tarai region of Uttar Pradesh (India). MATERIALS AND METHODS
Portions of thigh muscles of local pigs were collected in polythene bags in ice from nearby slaughter houses at Rudrapur and Haldwani. The muscles
0304-4017/90/$03.50
© 1990 Elsevier Science Publishers B.V.
344
A. SALEQUE ET AL.
were processed in the laboratory. The tissues, found heavily positive ( + + + ) for mature and maturing S. miescheriana microcysts, were separated and cleaned. The intensity of microcysts in the muscles was estimated using the following parameters: light ( + ), 1-5 cysts per 2 g of muscle; moderate ( + + ), 6-10 cysts per 2 g of muscle; heavy ( + + + ), more t h a n 10 cysts per 2 g of muscle. A total of 26 puppies, of nearly 3 months of age, were maintained and fed whole boiled milk and bread during the experimental period. Parasite-free puppies were used for the experiment. All the pups were randomly divided into 13 groups (1-13). Each group had two puppies. Groups 12 and 13 served as untreated infected and uninfected controls, respectively.
Experimental design In the heating experiment, the dogs of Groups 1-5 were fed pork infected with sarcocysts exposed to different temperatures (50-100°C). The heavily ( + + + ) infected muscles in pieces of 250 g for each t r e a t m e n t were heated at temperatures of 50, 60, 70 and 100°C for 20 min, 20 min, 15 min and 5-10 min, respectively. Pups of Groups 6-11 were used for feeding the same quantity of heavily infected muscles, kept at 4 °C for 7 days, at - 4 °C for 7, 2 and 1 days and at - 20 ° C for 2 and 1 days. Pups of Group 12 were given the same quantity of freshly collected heavily infected muscles and of Group 13 uninfected muscles. The criteria for assessing the infectivity of the sarcocysts were based on the appearance of sporocysts in the faeces of the pups fed treated or untreated infected muscles. The absence of sporocysts in the faeces for 30 days proved the physical t r e a t m e n t had a lethal effect on the sarcocysts. RESULTS The results are tabulated in Table 1. The exposure of sarcocysts in muscles to 50 ° C for 20 min could not make the cysts non-infective and sporocysts were seen in the faeces of two dogs on Days 9 and 12 post infection. T r e a t m e n t at 60°C, 70°C and 100°C for 20 min, 15 min and 5-10 min, respectively, made the cysts non-infective for pups because no sporocysts were seen in the faeces for 30 days post infection. Exposure of sarcocysts in muscles to 4 ° C for 7 days did not alter the infectivity, as proved by the presence of sporocysts in the faeces on Days 12 and 13 post infection. Similarly, feeding infected pork treated at - 4 °C for only one day showed that this procedure could not make it non-infective, as sporocysts appeared on 9 day post infection in both the pups. However, exposure to - 4 ° C for 7 and 2 days and to - 2 0 ° C for 2 and 1 day rendered the sarcocysts in muscles non-infective for the pups.
EFFECT OF TEMPERATURE ON S. MIESCHERIANA INFECTIVITY
345
TABLE 1 E f f e c t o n i n f e c t i v i t y of Sarcocystis miescheriana c y s t s in p o r k ( t h i g h m u s c l e s ) a f t e r e x p o s u r e to heating and freezing Group
Temperature of e x p o s u r e ( °C )
Time of exposure
Infectivity of sarcocysts to p u p s
Remarks
20 m i n
÷
Sporocysts seen on D a y s 9 a n d 12 p o s t infection
20 15 10 5 7
min min min min days
÷
1
50
2 3 4 5 6
60 70 100 100 4
7 8 9
- 4 - 4 - 4
7 days 2 days 1 day
÷
10 11 12
- 20 - 20 Fed untreated infected pork Fed uninfected pork
2 days I day Nil
÷
13
Sporocysts seen on D a y s 12 a n d 13 post infection
Sporocysts seen on Day 9 post i n f e c t i o n in b o t h pups
S p o r o c y s t s s e e n on D a y s 9 a n d 12 p o s t infection
Nil
DISCUSSION
The results of the heating experiment showed that the exposure of thigh muscles of pigs containing sarcocysts of S. miescheriana microcysts to 70 ° C for 15 min and to 100°C for 5 min made the cyst non-infective for puppies. These findings are in close agreement with those of Gestrich and Heydorn (1974) and Fayer (1975) for S. cruzi in cattle, Golubkov (1978) for S. fusiformis in buffaloes, Collins and Charleston (1980) for S. gigantea in sheep and of Srivastava et al. (1986) for S. levinei in buffaloes. However, refrigeration at 4 ° C for 7 days did not affect the infectivity of cysts. Freezing at - 4 ° C for 27 days and at - 2 0 ° C for 1-2 days showed lethal effects on the sarcocysts. Similar observations were reported by Gestrich and Heydorn (1974) in the
346
A. SALEQUE ET AL.
case o f s a r c o c y s t s in b e e f f r o z e n a t - 20 ° C for 4 - 6 days. S r i v a s t a v a et al. (1986) h a s also s t a t e d t h a t f r e e z i n g a t - 4 ° C f o r 48 h m a d e t h e s a r c o c y s t o f S. levinei in t h e c a r d i a c m u s c l e s o f b u f f a l o n o n - i n f e c t i v e f o r t h e final h o s t . ACKNOWLEDGEMENT Thanks are due to the Dean of the College of Veterinary Sciences, and to the D i r e c t o r o f t h e E x p e r i m e n t a l S t a t i o n , f o r t h e facilities p r o v i d e d .
REFERENCES Collins, G.H. and Charleston, W.A.G., 1980. Studies on Sarcocystis sp. VII. The effect of temperature on the viability of macrocysts (Sarcocystisgigantea) of sheep. N.Z. Vet. J., 28: 189-191. Fayer, R., 1975. Effect of refrigeration, cooking and freezing on Sarcocystis in beef from retail food stores. Proc. Helminthol. Soc. Wash., 42: 138-140. Gestrich, R. and Heydorn, A., 1974. Untersuchungen zur Uberlebensdauer von Sarkosporidienzystem in Fleisch von Schlachttieren. Berl. Munch. Tierarztl. Wochenschr., 87: 475-476. Golubkov, V.I., 1978. Resistance of Sarcocystis fusiformis to some physical factors applicable to meat. Veterinariya (Moscow), 5: 89-99. Srivastava, P.S., Saha, A.K. and Sinha, S.R.P., 1986. Effects of heating and freezing on the viability of sarcocysts of Sarcocystis levinei from cardiac tissues of buffaloes. Vet. Parasitol., 19: 329-332.
(1990) 343-346
343
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
Short communication
Effect of T e m p e r a t u r e on the I n f e c t i v i t y of Sarcocystis miescheriana Cysts in P o r k A. S A L E Q U E , P.D. J U Y A L a n d B.B. B H A T I A
Department of Parasitology, College of Veterinary Sciences, G.B. Pant University of Agriculture and Technology, Pantnagar-263145 (India) (Accepted for publication 16 January 1990)
ABSTRACT Saleque, A., Juyal, P.D. and Bhatia, B.B., 1990. Effect of temperature on the infectivity of Sarcocystis miescheriana cysts in pork. Vet Parasitol., 36: 343-346.
Sarcocysts of Sarcocystis miescheriana in the thigh muscles of pigs became non-infective to p u p s after heating infected pork in minute pieces at 60 ° C for 20 min, 70 ° C for 15 min and 100 ° C for 5 min. Similar pieces of infected muscle tissues, when exposed to - 4 ° C for 2 days or - 20 ° C for 1 day, became non-infective to pups. The experiment suggests that pork containing sarcocysts of S. miescheriana, and possibly of S. suihominis, requires cooking at a minimum of 70 ° C for 15 min or freezing at - 4 ° C for 2 days or - 20 ° C for 1 day for making it safe for consumption.
INTRODUCTION
The lethal effects of various temperature treatments such as cooking and freezing on the sarcocysts of Sarcocystis cruzi in beef, S. gigantea in mutton and S. levinei in the cardiac tissues of buffaloes have been reported (Fayer, 1975; Golubkov, 1978; Collins and Charleston, 1980; Srivastava et al., 1986). In order to control the transmission of sarcosporidia from intermediate hosts to the definitive hosts, particularly the species of zoonotic importance, i.e.S. hominis and S. suihominis from cattle and swine, respectively, to man, physical applications such as heating and freezing are of great significance. This communication reports the effects of heating, freezing and refrigeration on S. miescheriana from the muscles of local pigs slaughtered for human consumption in the Tarai region of Uttar Pradesh (India). MATERIALS AND METHODS
Portions of thigh muscles of local pigs were collected in polythene bags in ice from nearby slaughter houses at Rudrapur and Haldwani. The muscles
0304-4017/90/$03.50
© 1990 Elsevier Science Publishers B.V.
344
A. SALEQUE ET AL.
were processed in the laboratory. The tissues, found heavily positive ( + + + ) for mature and maturing S. miescheriana microcysts, were separated and cleaned. The intensity of microcysts in the muscles was estimated using the following parameters: light ( + ), 1-5 cysts per 2 g of muscle; moderate ( + + ), 6-10 cysts per 2 g of muscle; heavy ( + + + ), more t h a n 10 cysts per 2 g of muscle. A total of 26 puppies, of nearly 3 months of age, were maintained and fed whole boiled milk and bread during the experimental period. Parasite-free puppies were used for the experiment. All the pups were randomly divided into 13 groups (1-13). Each group had two puppies. Groups 12 and 13 served as untreated infected and uninfected controls, respectively.
Experimental design In the heating experiment, the dogs of Groups 1-5 were fed pork infected with sarcocysts exposed to different temperatures (50-100°C). The heavily ( + + + ) infected muscles in pieces of 250 g for each t r e a t m e n t were heated at temperatures of 50, 60, 70 and 100°C for 20 min, 20 min, 15 min and 5-10 min, respectively. Pups of Groups 6-11 were used for feeding the same quantity of heavily infected muscles, kept at 4 °C for 7 days, at - 4 °C for 7, 2 and 1 days and at - 20 ° C for 2 and 1 days. Pups of Group 12 were given the same quantity of freshly collected heavily infected muscles and of Group 13 uninfected muscles. The criteria for assessing the infectivity of the sarcocysts were based on the appearance of sporocysts in the faeces of the pups fed treated or untreated infected muscles. The absence of sporocysts in the faeces for 30 days proved the physical t r e a t m e n t had a lethal effect on the sarcocysts. RESULTS The results are tabulated in Table 1. The exposure of sarcocysts in muscles to 50 ° C for 20 min could not make the cysts non-infective and sporocysts were seen in the faeces of two dogs on Days 9 and 12 post infection. T r e a t m e n t at 60°C, 70°C and 100°C for 20 min, 15 min and 5-10 min, respectively, made the cysts non-infective for pups because no sporocysts were seen in the faeces for 30 days post infection. Exposure of sarcocysts in muscles to 4 ° C for 7 days did not alter the infectivity, as proved by the presence of sporocysts in the faeces on Days 12 and 13 post infection. Similarly, feeding infected pork treated at - 4 °C for only one day showed that this procedure could not make it non-infective, as sporocysts appeared on 9 day post infection in both the pups. However, exposure to - 4 ° C for 7 and 2 days and to - 2 0 ° C for 2 and 1 day rendered the sarcocysts in muscles non-infective for the pups.
EFFECT OF TEMPERATURE ON S. MIESCHERIANA INFECTIVITY
345
TABLE 1 E f f e c t o n i n f e c t i v i t y of Sarcocystis miescheriana c y s t s in p o r k ( t h i g h m u s c l e s ) a f t e r e x p o s u r e to heating and freezing Group
Temperature of e x p o s u r e ( °C )
Time of exposure
Infectivity of sarcocysts to p u p s
Remarks
20 m i n
÷
Sporocysts seen on D a y s 9 a n d 12 p o s t infection
20 15 10 5 7
min min min min days
÷
1
50
2 3 4 5 6
60 70 100 100 4
7 8 9
- 4 - 4 - 4
7 days 2 days 1 day
÷
10 11 12
- 20 - 20 Fed untreated infected pork Fed uninfected pork
2 days I day Nil
÷
13
Sporocysts seen on D a y s 12 a n d 13 post infection
Sporocysts seen on Day 9 post i n f e c t i o n in b o t h pups
S p o r o c y s t s s e e n on D a y s 9 a n d 12 p o s t infection
Nil
DISCUSSION
The results of the heating experiment showed that the exposure of thigh muscles of pigs containing sarcocysts of S. miescheriana microcysts to 70 ° C for 15 min and to 100°C for 5 min made the cyst non-infective for puppies. These findings are in close agreement with those of Gestrich and Heydorn (1974) and Fayer (1975) for S. cruzi in cattle, Golubkov (1978) for S. fusiformis in buffaloes, Collins and Charleston (1980) for S. gigantea in sheep and of Srivastava et al. (1986) for S. levinei in buffaloes. However, refrigeration at 4 ° C for 7 days did not affect the infectivity of cysts. Freezing at - 4 ° C for 27 days and at - 2 0 ° C for 1-2 days showed lethal effects on the sarcocysts. Similar observations were reported by Gestrich and Heydorn (1974) in the
346
A. SALEQUE ET AL.
case o f s a r c o c y s t s in b e e f f r o z e n a t - 20 ° C for 4 - 6 days. S r i v a s t a v a et al. (1986) h a s also s t a t e d t h a t f r e e z i n g a t - 4 ° C f o r 48 h m a d e t h e s a r c o c y s t o f S. levinei in t h e c a r d i a c m u s c l e s o f b u f f a l o n o n - i n f e c t i v e f o r t h e final h o s t . ACKNOWLEDGEMENT Thanks are due to the Dean of the College of Veterinary Sciences, and to the D i r e c t o r o f t h e E x p e r i m e n t a l S t a t i o n , f o r t h e facilities p r o v i d e d .
REFERENCES Collins, G.H. and Charleston, W.A.G., 1980. Studies on Sarcocystis sp. VII. The effect of temperature on the viability of macrocysts (Sarcocystisgigantea) of sheep. N.Z. Vet. J., 28: 189-191. Fayer, R., 1975. Effect of refrigeration, cooking and freezing on Sarcocystis in beef from retail food stores. Proc. Helminthol. Soc. Wash., 42: 138-140. Gestrich, R. and Heydorn, A., 1974. Untersuchungen zur Uberlebensdauer von Sarkosporidienzystem in Fleisch von Schlachttieren. Berl. Munch. Tierarztl. Wochenschr., 87: 475-476. Golubkov, V.I., 1978. Resistance of Sarcocystis fusiformis to some physical factors applicable to meat. Veterinariya (Moscow), 5: 89-99. Srivastava, P.S., Saha, A.K. and Sinha, S.R.P., 1986. Effects of heating and freezing on the viability of sarcocysts of Sarcocystis levinei from cardiac tissues of buffaloes. Vet. Parasitol., 19: 329-332.
