Background Sarcocystis are intracellular protozoan parasites among the most commonly found parasites in domestic ruminants in most countries of the world. The parasite ultimately disseminates to skeletal, cardiac, and smooth muscle, that are infectious for a definitive host, acquired by eating undercooked beef or pork. Infection may be asymptomatic or a possible cause of musculoskeletal complaints and can provoke eosinophilic myositis. Rheumatoid arthritis (RA) patients may have high titres of rheumatoid factor in several parasitic diseases (Kiel, 2002 and Frank von Sonnenburg, 2011).
Objectives to evaluate the clinical presentation and serology of sarcocystosis infection in patients with non-specific rheumatic complaints and patients with rheumatoid arthritis.
Methods This study included 22 non-specific musculoskeletal patient, 21 RA patients and 10 healthy controls. They were 39 females and 4 were males with a mean age of 20.5 years. They were selected from the rheumatology and rehabilitation department in Assiut university hospital. Using the sarcocystis fusiformis antigen (Ag), prepared by sodium dodecyl sulphate polyacrylamide gel electrophoresis, serum samples of the patients and controls were tested for the presence of sarcocystis species antibodies, using Western Blot technique, ESR, ASOT, RF, ANA, CPK, CBC and differential blood count.
Results Positive reaction to sarcocystosis infection was present in 63,7% of non-specific musculoskeletal patients and 23.8% in RA patients. By the use of Western Blot technique, the most reactive bands were the wide band 23-24 kD and the deeply stained band at 26 kD. They detected several band ranges from 15-116 KD. The most reactive bands were at 116, 100, 52 and a wide band at 32 kD. High sarcocystis Ag positivity was detected in nonspecific musculoskeletal pain, while it was low in RA patients. In non-specific musculoskeletal pain, 77.3% of patients infected with sarcocystis, and they developed myositis, characterized by localized painful muscular swelling, and slight fever, with predilection to quadriceps muscle, 40,9% had arthralgia, 59.1% had arthritis mostly in knees. A positive correlation was found between Ag positivity and myositis. All the seropositive cases (20%) had eosinophilia. Sarcocystis might be an overlooked cause of unexplained eosinophilia. Three patients (13,6%) had myocarditis in and they were positive to sarcocystis Ag. One of them reacted strongly with the Ag and had associated bronchospasm. Chest infection was presented in 18,2%. Activity was measured by a moderate increase of ESR and mild decrease in haemoglobin level. In RA patients, only 9,5% had myositis with positive Ag. A statistically significant difference between the two groups was found (P<0.04).
Conclusions Sarcocystis infection may be an important cause of the non-specific rheumatic diseases and may be associated with myositis and marked elevation of Sarcocystis Ag seropositivity. Non-specific rheumatic patients must be tested for Western Blotting and eosinophila. Rheumatoid arthritis patients are less affected by sarcocystosis.
Kiel RJ (2002): Sarcosporidiosis. Medicine Journal, May 3(5):1-10.
Frank von Sonnenburg (2011): Acute Muscular Sarcocystosis among Returning Travelers, Tioman Island, Malaysia, Morbidity and Mortality. Weekly Report (MMWR)
Disclosure of Interest : None declared