Choi and colleagues report two small outbreaks in Korea of acute toxoplasmosis in immunocompetent hosts attributed to ingestion of raw porcine viscera and meat. In the first instance, three individuals who ate raw boar meat and spleen developed unilateral blindness approximately two months later. In the second outbreak, five soldiers developed lymphadenopathy one month after eating raw meat and liver of a domestic pig. All eight patients had serological evidence of acute toxoplasmosis. Examination of a lymph node biopsy specimen from one patient revealed findings consistent with acute toxoplasmosis.
All patients received anti-toxoplasma therapy with either pyrimethamine-sulfa or pyrimethamine alone. In one patient with lymphadenopathy, treatment was terminated after one week because of the development of Stevens-Johnson syndrome for which the patient received corticosteroids. One of three patients with chorioretinitis improved and was left with 20/20 vision; the other two remained blind in one eye as a result of macular scarring.
COMMENT BY STAN DERESINSKI, MD, FACP
Newly acquired Toxoplasma infection of the immunocompetent host is asymptomatic in at least 80-90% of instances. The most common clinical manifestation in this population is nontender cervical lymphadenopathy. In most instances, the clinical course is self-limited, and treatment is not required or indicated. Some patients may go on to have persisting or fluctuating lymphadenopathy, however. In addition, a small proportion may develop a visceral complication, such as myocarditis, encephalitis, or pneumonitis. Chorioretinitis, while a common complication of congenital toxoplasmosis, is an unusual manifestation in the otherwise normal adult. Furthermore, congenital toxoplasma chorioretinitis is commonly bilateral while in the adult with acquired infection it is usually unilateral, as in the cases here. The cases reviewed here are unusual in that each outbreak was associated with different manifestations, suggesting that strains of Toxoplasma gondii may have varying tissue tropisms.
These outbreaks remind us of the importance of food as a source of infection with T. gondii. While cats and congenitally acquired infection seem to get all the publicity, most cases of toxoplasmosis are probably acquired as the result of eating undercooked meat (or viscera) containing the cyst form of T. gondii. Up to one-fourth of lamb and pork samples may contain T. gondii cysts, while their presence in beef is less common. Food, including vegetables, can also be contaminated externally, and outbreaks associated with contaminated water have also been reported. Toxoplasmosis has also been transmitted via transfusion of cellular blood products and by organ transplantation.
External contamination of food can be prevented by careful washing of hands and food. Cooking to 66°C, smoking, curing, and freezing to -20°C are each capable of rendering cysts non-infectious. Because of reports of internal contamination of eggs, these should also not be eaten uncooked. Unpasteurized milk has also been suggested as a possible source of T. gondii cysts and should, of course, be avoided. Cats commonly excrete oocysts, and care should be taken, particularly in the handling of their litter. Daily cleaning of the litter pan, however, should deny oocysts the opportunity to sporulate and thus become infectious.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content