Question

Case Study #7 A ten year child is showing signs of toxoplasmosis. The physician has ordered the family and cats to be tested for the disease. Toxoplasmosis results from an infection with Toxoplasma gondii which is a parasitic protozoan that infects humans by ingestion of the infective oocysts. The oocysts are transferred by hand-to-hand contact from soil or cat litter or by ingestion of raw or partially cooked pork, mutton, or beef. Transmission may also occur through blood transfusions or organ transplantation. Cats are known to be definitive hosts for this parasite. An Enzyme Immunoassay (EIA) was run to determine antibody titers to the parasite. Patient serums samples were diluted 1:10 in the first well. Two-fold dilutions were done through Well 8. ((+) = antibody was detected / (-) = antibody not detected) Negative and positive controls confirmed the results. Well number Patient 5 6 7 Child Mom Dad Sister Fluffy Buster + N + w + + + + + + + + + + + + + + + + + + + + + + + 1. What are the titers for each of the patient samples? 2. Which patients have been exposed to Toxoplasmosis gondii? 3. What symptoms may the patient exhibit? 4. What other serological tests are used to diagnose toxoplasmosis?

Answer 1

Two fold serial dilution is done here. initial 1in 10 means 1+9ml . In the 1st tube make it 2ml+18 ml so that you can take 10 ml from 1st test tube to transfer it to 2nd test tube. Initially you give 10ml reagent to all the rest  test tubes. now serially transfer from 1st one to 2nd test tube 10 ml.i in 10 diluted mixture. MIX it. Take 10 ml from second mixture and transfer it to 3rd TT.and Go on like this.means in a 10 ml serum dilution you add 10 ml of testing reagent. in this questions they are doing 2 fold serial dilution in the rest .so upto 5 no test tube dilution will be 1in10( 1 initial given) 1in 20(2nd test tube) 1in 40(3rd TEST tube)1in 80(4th TT) and 1in 160 in 5th Test tube. so titre is 160 in child

Similarlly in mom it is 640 titre , dad 0 titre sister 320 fluffy titre 640 and buster with titre 1280

The patients having high antibody titre e.g 160 generated against T.gondii are affected by the parasite. If the antibody IGM then recent one.

most cases of toxoplasmosis in immune competent host are asynptomatic but symptoms are severe in immunocompromised host. where central nervous system are primarily affectede.g encephalopathy meningo enchephalopathy etcor cerebral mass etc occur involving motor function.

Other tests are Sabin Feldman Dye test,Indirect fluorescent antibody assay etc..