[Experimental infection of Sarcocystis suihominis in pig and human volunteer in Guangxi]

Abstract

Objective: To confirm existence of Sarcocystis suihominis and possible transmission cycle between human and pigs.

Methods: Based on the human-pig-human infection cycle of Sarcocystis suihominis, feces of naturally infected pigs were collected and over 10,000 sporocysts were received by flotation technique, which were mixed with fodder to infect a normal pig. Fresh pork meat containing mature sarcocysts was chopped into pieces and swallowed by a volunteer (the first author of this paper) with about 71,000 sporocysts. Symptoms and development of the parasites after infection were observed.

Results: The volunteer showed abdominal distension in about 5 hours after infection, with watery diarrhea 13 times from the 8th to 36th hour, vomiting 4 times, chilling and fever with a temperature of 38.5 degrees C, dizziness, headache, joint and muscle ache, epigastralgia, and anorexia. Un-sporized sporocysts were found in the faces 10 days after infection and sporocysts appeared on the 12th day. The average size of sporocysts was 11.9 (8.8-14.5) microm x 9.2 (7.5-12.5) microm. The infected pig showed a slight anorexia, fatigue, constipation, hair loosen in 5-8 days after infection, and returned normal on the 17th day. The average size of the sarcocysts was 299.2 (175-575 ) microm x 62.3 (30-102.5) microm. Size of bradyzoites was 11.5 (9.5-13.5) microm x 4.1 (2.8-5.0) microm. The volunteer was treated with acetylspiramycin for 15 days (0.2 g/time, 4 times/d) after 46 days of infection, and fecal examination turned negative 30 days later.

Conclusion: There is a man-pig cycle for Sarcocystis suihominis in Guangxi.