Toxoplasmosis

Toxoplasma gondii is a protozoan parasite that infects up to a third of the world's population. Infection is mainly acquired by ingestion of food or water that is contaminated with oocysts shed by cats or by eating undercooked or raw meat containing tissue cysts. Primary infection is usually subclinical but in some patients cervical lymphadenopathy or ocular disease can be present. Infection acquired during pregnancy may cause severe damage to the fetus. In immunocompromised patients, reactivation of latent disease can cause life-threatening encephalitis. Diagnosis of toxoplasmosis can be established by direct detection of the parasite or by serological techniques. The most commonly used therapeutic regimen, and probably the most effective, is the combination of pyrimethamine with sulfadiazine and folinic acid. This Seminar provides an overview and update on management of patients with acute infection, pregnant women who acquire infection during gestation, fetuses or infants who are congenitally infected, those with ocular disease, and immunocompromised individuals. Controversy about the effectiveness of primary and secondary prevention in pregnant women is discussed. Important topics of current and future research are presented.     

Toxoplasmosis

Recent advances in understanding toxoplasmosis have been made in the areas of the basic biology of the parasite and the host-parasite interaction, especially the cellular immune response. There is new insight into the biology of the cyst stage that is responsible for meat-associated transmission of infection and for the reactivation of disease in chronically infected humans. Fewer recent advances have been made in clinical diagnosis and treatment of toxoplasmosis. The fascinating revelation that Toxoplasma gondii contains an organelle—now known as the apicoplast—that derives from an algal endosymbiont, has opened many avenues of basic investigation. An understanding of the fundamental biology of T. gondii promises future progress in prevention or treatment of toxoplasmosis.     

Toxoplasmosis in pregnancy

Pregnant women who acquire infection from Toxoplasma gondii usually remain asymptomatic, although they can still transmit the infection to their fetuses with severe consequences. Given the asymptomatic nature of most Toxoplasma infections, primary prevention in pregnant women may lower the risk of congenital toxoplasmosis. Both consumption of undercooked meat and unprotected contact with soil are independent risk factors for T. gondii seroconversion during pregnancy, while contact with cat litter may pose a risk in certain situations. However, many pregnant women lack knowledge of these risk factors. This article reviews toxoplasmosis infection in pregnancy, with an emphasis on risk factors and appropriate counseling of pregnant women.     

Toxoplasmosis in hairy-cell leukaemia

Toxoplasma serology was performed in 28 patients with hairy-cell leukaemia and was positive in eight patients (29%). In two patients (7%) reactivated toxoplasmosis was proven by either isolation of Toxoplasma gondii or by significant antibody titre rise with generation of specific IgM-antibodies. In four patients (14%), a clinical diagnosis of active toxoplasmosis was based on signs and symptoms, serologic tests, and response to specific treatment. The high proportion of patients in which active toxoplasmosis was proven or probable (six; 21%) may be related to the presence of severe monocytopenia. In patients with hairy-cell leukaemia developing fever of unknown origin and myositis, toxoplasma serology should be performed, particularly because treatment of active toxoplasmosis usually is successful.     

弓形虫病的现代治疗

弓形虫病广泛分布于世界各地 ,人群平均感染率为2 5 %～ 5 0 %。弓形虫能寄生在人及 190多种动物体内 ,严重危害人畜健康。目前 ,弓形虫病的传统治疗仍以乙胺嘧啶与磺胺嘧啶合用为主 ,虽取得一定疗效 ,但常由于抑制骨髓、损害肝功能、易出现皮疹等毒副作用而被迫停止用药。尤其是弓形虫脑炎、先性弓形虫病胎儿及免疫缺陷病人不能耐受长程治疗 ,停药后复发率高 ,根治效果差。为此 ,国内外许多学者对弓形虫病的治疗不断进行探索〔1〕,本文为其研究概述 ,为临床治疗该病提供参考。1　化学治疗1 1　大环内酯抗生素　螺旋霉素 (Ｓｐｉｒａｍｙｃ…     

Toxoplasmosis in immunosuppression and AIDS

Summary Reactivation of chronic, latent infection ofToxoplasma gondii has been observed previously in transplant patients and malignancies treated with immunosuppressive drugs. Recently it has emerged as the most common recognized central nervous system infection in acquired immunodeficiency syndrome (AIDS) patients, seen in 6–20% of all AIDS cases. It produces diffuse encephalopathy or space-occupying and necrotic lesions. Contrary to classical toxoplasmosis, the serological diagnosis is unreliable and the therapeutical response in most cases is poor.

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Toxoplasmose bei Immunsuppression und AIDS

Zusammenfassung Die Reaktivierung einer chronischen, latenten Infektion mitToxoplasma gondii wurde in jüngerer Zeit bei Transplantationspatienten und nach Behandlung von Malignomen mit Immunsuppressiva beobachtet. Neuerdings tritt die Toxoplasmose als die häufigste Infektion des Zentralnervensystems bei Patienten mit erworbenem Immundefizienz-Syndrom (AIDS) auf und wird bei 6–20% aller AIDS-Fälle beobachtet. Die Toxoplasma-Infektion führt zur diffusen Enzephalopathie oder zu raumfordernden, nekrotisierenden Läsionen. Im Gegensatz zur klassischen Toxoplasmose ist die serologische Diagnostik unzuverlässig, die meisten Fälle sprechen schlecht auf die Therapie an.