Toxoplasmosis By : Suhad Azzam

Toxoplasmosis Toxoplasmosis is one of the zoonotic diseases. Etiologic agent = Toxoplasma gondii. Etiologic agent = Toxoplasma gondii Toxoplasmosis is one of the best known zoonotic diseases among physicians, veterinarians and the public. The etiologic agent, Toxoplasma gondii, is a coccidian protozoan pathogen of humans and a variety of animal species. In all hosts, the organism enters a chronic, persistent phase following acute infection, and this persistence leads to the potential for reactivation of clinical disease at a later date (a particularly serious problem in AIDS patients). Cats play a critical role in the life cycle and maintenance of the organism in nature. Cats are, in fact, the only definitive host in which T. gondii can undergo sexual reproduction to produce infectious oocysts/sporozoites. However, humans can be infected with Toxoplasma gondii by 3 different mechanisms, only one of which is direct contact with cat feces. Therefore, the overall role of cats in the epidemiology of human exposure to T. gondii needs to be viewed from a basis in fact, not fear.

Historical Facts--Toxoplasmosis T.Gondii was first discovered in 1908 in Tunis within the tissue of the gondi, in the same year it was also described in Brazil in rabbits. Rediscovered in 1935 in the brain tissue of guinea pigs. In 1939 it was found as the cause of encephalitis in a 31 day old infant. In 1969 infective cysts were detected in the stools of cats. T. gondii constructing daughter scaffolds within the mother cell

Host Intermediate host Mainly domestic and wild cats. Human, birds, pigs, rodents, and sheep.

Toxoplasma gondii, Life-cycle

The protozoa multiplies sexually in the cat’s intestinal and asexually in a many mammals and even birds. Infective stage: Oocyst full of sporocyst. Zoiocyst full of bradyzoites.

Toxoplasma gondii ACUTE PHASE CHRONIC PHASE Immunity + Tachyzoites: rapidly dividing forms Immunity - Bradyzoites: slowly dividing forms ACTIVATION

Toxoplasmosis oocyst Tachyzoite stage

Transmission Transmission of infection: 1: Congenital . 2: Acquired : 3: Reactivation of infection Immunocompromised e.g. AIDS Immunosuppression e.g. drugs

Congenital toxoplasmosis Transmission of T. gondii to the fetus generally only occurs during an acute infection of the mother, not during latency. Fetal infection is one of the greatest fears of toxoplasmosis and is probably the situation in which veterinarians and physicians are most often called upon for advice by clients/patients. Unfortunately, the time for clients/patients to ask questions and learn about the disease should be before becoming pregnant, but too often questions arise only after the fact. (Hence, the importance of on-going client/patient education as part of your practice/professional activity.) There are about 400-4,000 cases of congenital toxoplasmosis in the U.S. yearly. Transmission of T. gondii to the fetus generally only occurs during an acute infection of the mother, not during latency (see below regarding HIV mothers). Therefore, risk of congenital infection of a fetus is restricted to those mothers who are actively infected during pregnancy, or within 6-8 weeks immediately prior to conception. Confirmation of acute infection during or immediately prior to pregnancy is based upon detection of anti-Toxoplasma IgM antibodies. However, this is not fool-proof system. A (-) IgM titer has a 100% predictive value against recent infection, but a (+) titer has a much lower predictive value for recent infection, because anti-Toxoplasma IgM titers can remain elevated for 2-6 months. Using a combination of IgM assays improves the predictive value for recent infection to 80%. Congenital infection can also be diagnosed by detection of anti-Toxoplasma IgM, IgA or IgE antibodies in the fetus/neonate or detection by immunoblot of specific IgG antibodies in the newborn that are not present in the mother's serum. If a woman has IgG Ab to T. gondii, this is evidence of past infection and she should not be at risk for congenital transmission to her baby (as long as she is also not HIV [+] or otherwise immunosuppressed). Women with AIDS may be able to reactivate their infection with subsequent infection of their fetus. Overall, estimates suggest that 50-70% of women in the U.S. are at risk (previously uninfected) for infection with T. gondii during pregnancy.

Congenital Toxoplasmosis

Symptoms Infection is usually asymyomatic in healthy individuals. In acute infection: Lymphadenitis is the most common in humans. Flu-like symptoms (Headache, fever, muscle pain) the infection is generally self limited & symptom usually resolve in few months.

Symptoms Causes Encephalitis, hiptitis, for immunosuppressed patients and people infected with (AIDS). Congenital neurological defects in infants. Abortion. In chronic infections: visual problems or blindness may occur over time.

Diagnosis Biopsy of humans. (ELISA) Enzyme-Linked Immuno sorbent Assays. (IFAT) Indirect Fluorescent Antibody tests.

Diagnostics Serology. Direct identification of parasite from peripheral blood, amniotic fluid or in tissue.

Treatment of Toxoplasmosis Usually not required. Sulfadiazine and pyrimethamine are two drugs widely used to treat toxoplasmosis in humans. Patients allergic to sulfa drugs may take Clindamycin, Clarithromycin, Azithromycin.

Prevention & Control Hands should be washed after contact with raw meat or in contact with soil. Vegetables should be washed well . Avoid undercooked meats. •If you are owned by a cat – Keep it inside if possible. – Don’t feed it raw meat. –Avoid cat for pregnant women.

Geographic Distribution Worldwide Infection is more common in warm climates and lower altitudes than cold climates and mountainous regions. 750 human deaths per year make it the 3rd most common lethal food poisoning. It is common where raw meat is served. 18

Seroprevalence of Toxoplasma gondii among infertile women attending in vitro fertilization center, Gaza strip, Palestine In the present study, the seroprevalence of Toxoplasmia gondii in Palestinian women was determined through antenatal screening. The study included 1954 Palestinian women records which were reviewed and analyzed statistically from 2000-2005 , Those women attended In vitro fertilization center in Gaza complaining from infertility and abortion. Anti-Toxoplasma, IgM antibodies were assayed using an enzyme linked immunosorbent assay (ELISA). Positive results were found in 7.9% for T. gondii, A high significant infection rate was observed in year 2003 (P = 0.001) for T. gondii. A clear variation with statistical significance was observed in the seroprevalence for all the studied pathogens regarding year of collection and age of women. The study indicated that T. gondiiis still constitute a public health problem among pregnant women and considered one of the abortion factor.

Seroprevalence and associated risk factors of toxoplasmosis in pregnant women in Hebron district, Palestine To measure the prevalence of toxoplasmosis, 204 pregnant women were tested for IgG and IgM antibodies to Toxoplasma gondii using an enzyme-linked immunoassay. The study was conducted in Hebron district during the year 2005. The seroprevalence of IgG antibodies to T. gondii was 27.9% from rural areas (36.8%) had IgG antibodies to T. gondii than urban women (21.4%). Possible routes of infection were contaminated soil, drinking rainwater and eating raw vegetables rather than eating uncooked meat or contact with cats. The prevalence of previous abortion was 37.3%, with a slight (but not statistically significant) association with toxoplasmosis .

Seroprevalence and risk factors for Toxoplasma infection in pregnant women in Jordan. To determine the seroprevalence and risk factors for toxoplasmosis among pregnant women in Jordan, sera from 280 pregnant women were tested during the period January 2000- May 2001. Blood samples were taken after the first antenatal visit. Serum was separated and tested for Toxoplasma IgG antibodies using an indirect fluorescent antibody. Seroprevalence gradually increased with age, from 31.7% at 15-24 years to 90.0% at 35-45 years. Regression analysis showed that seroprevalence of toxoplasmosis is positively correlated with age and residence. Consumption of undercooked meat and contact with soil were significant risk factors.

Seroprevalence of Toxoplasma antibodies among individuals tested at hospitals and private laboratories in Beirut. This is a retrospective study targeting information related to IgG and IgM anti-T. gondii antibodies among females tested at different hospitals and private laboratories in Beirut. The vast majority (around 96%) of the tested population were females with age ranging between 16 yrs and 40 yrs (i.e. mostly females at childbearing age). The seroprevalence of IgG anti-T. gondii antibodies determined on 3516 sera from hospital laboratories and private laboratories was 62.2% . The IgM anti-T. gondii antibodies determined on 3426 sera from hospital laboratories and private laboratories was 6.8%. Based on this seroprevalence study, exposure to toxoplasm infection is considered high among the Lebanese population and it increases with advanced age. This current information reflects the endemicity of this disease in Lebanon.

Anti-Toxoplasoma gondii antibodies among volunteer blood donors in eastern Saudi Arabia. A cross-sectional study was conducted to evaluate the risk factors of Toxoplasma gondii in 100 volunteer blood donors at blood bank. . A required data were taken through a designed questionnaire. Five ml. venous blood samples .Anti-Toxoplasma antibodies were evaluated by using ELISA. The results showed that 40 volunteers (40%) were positive for anti-T. gondii IgG antibodies. . These findings highlight the prevalent T. gondii among blood donors and focused on the risk factors. It was recom-mended that blood donors should be free from Toxoplasma antibodies.

Toxoplasma gondii seropositivity and co-infection with TORCH pathogens in high-risk patients from Qatar. This study included 1,857 patients between 2005 and 2008. Logistic regression was used to evaluate factors associated with Toxoplasma gondii seropositivity. Among 823 women of childbearing age, 35.1% and 5.2% tested positive for T. gondii IgG and IgM, respectively. Three infants < or = 6 months of age (0.8% of 353) were congenitally infected.