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„Approved”
on methodical conference
department of infectious diseases and epidemiology
„____” ____________ 200 р.
Protocol № _____
Chief of Dept., professor __________ V.D. Moskaliuk
METHODOLOGICAL INSTRUCTIONS
to a fifth year student of the Faculty of Medicine
on independent preparation for practical training
Topic: TOXOPLASMOSIS
Subject:
Major:
Educational degree and qualification degree:
Year of study:
Hours:
Assistant professor
Infectious Diseases
Medicine
Specialist
5
2
Sydorchuk A.S.
Topic: TOXOPLASMOSIS
1. Lesson duration: 2 hours
2. Aims of the lesson:
3.1. Students are to know:
 Etiology and epidemiology of a toxoplasmosis;
 Pathogenesis and pathological anatomy;
 Classification of a toxoplasmosis;
 The clinical characteristic of different kinds of a toxoplasmosis;
 Laboratory methods of examination at toxoplasmosis;
 Complications, which are observed at a toxoplasmosis;
 Differential diagnostics of a toxoplasmosis;
 Medical tactics;
 Preventive and antiepidemic measures in the locus.
3.2. Students are to be able:
• to question a patient in order for obtaining of information on disease history and
epidemiologic anamnesis;
• to perform clinical examination of a patient;
• to formulate and to substantiate the diagnosis of toxoplasmosis;
• to prepare a plan of additional patient examination;
• to evaluate results of laboratory examination;
• to make differential diagnosis to distinguish between similar diseases;
• to prescribe adequate pathogen and etiotropic treatment.
3.3. Students are to acquire the following skills:
 to conduct clinical examination of a toxoplasmosis patient;
 to formulate and substantiate a clinical diagnosis;
 to prepare a plan of paraclinic patient examination;
 to evaluate results of paraclinic patient examination;
 to organize hospitalization and treatment of a toxoplasmosis patient;
 to plan and organize prophylactic measures against toxoplasmosis.
4. Advice to the student:
Infectious agent of Toxoplasmosis is Toxoplasma gondii, a protozoal disease.
Toxoplasmosis infection is asymptomatic in 80% of people. The most common sign in
symptomatic patients is enlarged lymph nodes, especially around the neck. The illness
may mimic glandular fever with other symptoms of muscle pain, intermittent fever and
malaise.
Dormant infection persists for life and can reactivate in the immunosuppressed person.
More serious disease can develop or reactivate in immunosuppressed patients with
brain, heart or eye involvement, pneumonia and occasionally death. Cerebral
toxoplasmosis or chorioretinitis are frequent complications of AIDS when the
lymphocyte CD4 cell count drops below 100 / cu mm. Acute toxoplasmosis in
pregnant women can affect the unborn child. In early pregnancy brain damage as well
as liver, spleen and eye disorders may occur. Infection in late pregnancy may result in
persistent eye infection through life. Toxoplasmosis acquired after birth usually results
in no symptoms or only a mild illness.
Method of diagnosis
Infection may be diagnosed by visualisation of the protozoa in biopsy material or
serology. Serological results require careful interpretation and should preferably be
performed and discussed with a reference laboratory. In general, toxoplasma-specific
IgG antibody appears two to three weeks after acute infection, peaks in six to eight
weeks and often persists lifelong. Presence of toxoplasma-specific IgM antibody
suggests infection within the last two years. False positive IgM results are common and
should always be repeated before final interpretation. They are common in
autoimmune disease. Presence of IgA antibodies is said to correlate with acute
infection. Testing paired sera taken two weeks apart is often helpful as is IgG antibody
avidity testing. A specific PCR performed on amniotic fluid may determine if a foetus
has become infected.
Incubation period
The incubation period is uncertain but probably ranges from 5–23 days. Public health
significance and occurrence Toxoplasmosis occurs worldwide in mammals and birds.
Infection in humans is common. Infections during pregnancy may lead to severe
complications for the foetus. Primary or reactivated lesions may lead to severe
complications in immunosuppressed patients.
Reservoir The main host is the domestic cat. Cats acquire the infection mainly
through eating small infected mammals including rodents and birds, and rarely from
the ingestion of infected cat faeces. Only young felines harbor the parasite in the
intestinal tract, where the sexual stage of the life-cycle takes place resulting in the
excretion of oocysts in faeces for 10–20 days. Many other intermediate hosts including
sheep, goats, rodents, cattle, swine, chicken and birds may carry an infective stage of
T. gondii encysted in their tissues. This occurs more commonly in muscle and brain.
Tissue cysts remain viable for long periods.
Mode of transmission
Adults most commonly acquire toxoplasmosis by eating raw or undercooked meat
infected with tissue cysts. Consumption of contaminated, unpasteurised milk has also
been implicated. Children may become infected by ingestion of oocysts in dirt or
sandpit sand after faecal contamination by cats, particularly kittens, or other animals.
The infection may also be transmitted through blood transfusion and organ
transplantation. Transplacental transmission may occur when a woman has a primary
infection during pregnancy.
Period of communicability
Toxoplasmosis is not transmitted from person to person spread except in-utero.
Oocysts spread by cats sporulate and become infective one to five days later. They may
remain infective in water or moist soil for over a year. Tissue cysts in meat remain
infective for as long as the meat is edible and undercooked.
Susceptibility and resistance
Everyone is susceptible to infection. About 75% of women of childbearing age are
susceptible. Immunity is thought to be life long however patients undergoing
immunosuppressive therapy, in particular for haematological malignancies, or patients
with AIDS, are at high risk of developing illness from reactivated infection.
Control measures
Preventive measures
No immunisation is available. Pregnant women and immunosuppressed people should
be advised to:
• cook meat thoroughly (until no longer pink) and avoid uncooked cured meat products
• not consume unpasteurised milk or its products
• wash all raw fruit and vegetables carefully before eating
• wash hands thoroughly before meals and after handling raw meat
• delegate the cleaning of cat litter trays to others wherever possible and if this is not
possible, gloves should be worn during cleaning and hands washed well afterward
• cat litter trays should be emptied daily and regularly disinfected with boiling water to
dispose of the oocysts before they become infective.
Cats should only be fed with dry, canned or boiled food and should be discouraged
from hunting and scavenging. However, direct contact with cats is rarely the cause of
infection. Cats are generally infected as kittens and only excrete the oocysts for two
weeks after their original infection.
Sandpits should be covered when not in use to stop cats defecating in the pit.
Control of case
Isolation of patient is not required. Specific anti-protozoal treatment may be indicated
in immunosuppressed persons, infections during pregnancy, or where there is eye or
other organ involvement. Specialist advice should be sought. Immunosuppressed
persons may also require prophylactic treatment for the duration of their
immunosuppression. Infants who acquire an infection before birth may require
prolonged treatment to reduce the risk of ongoing active infection. Children of
mothers with evidence of previous immunity more than six months prior to conception
are not at risk. Primary infection in pregnancy is rare although up to one third of these
infections result in transplacental spread to the developing foetus. Primary infection in
pregnancy can cause serious foetal disease. Infection in the first trimester results in a
low foetal infection rate (15%) but a higher risk of serious disease. Infection later in
pregnancy results in a higher infectionrate but generally less severe disease. Diagnosis
and treatment during pregnancy appears to reduce the effects on the baby. False
positive IgM antibody test (and less commonly IgG) results do occur and treatment
should never begin without further testing. Where infection of the mother is confirmed,
treatment is indicated. Amniocentesis with PCR testing can be carried out to determine
whether transmission to the foetus has occurred.
5. Control questions:
1. Give the characteristic of the originator of toxoplasmosis.
2. Who is a source of an infection contamination at toxoplasmosis?
3. Name possible mechanisms and paths of transfer of an toxoplasmosis.
4. Name the basic phases of a pathogeny of toxoplasmosis.
5. Clinical forms of toxoplasmosis and their feature.
6. Name possible complications of toxoplasmosis.
7. With what diseases it is necessary to differentiate toxoplasmosis?
8. List the basic criteria for an establishment of the diagnosis:
"toxoplasmosis ".
9. What principles of antibacterial therapy of toxoplasmosis.
10. Pathogenetic treatment of toxoplasmosis.
6. REFERENCES.
А. Basic:
Infectious disiseases /Edited by: prof. E. Nikitin, prof. M. Andreychyn.-Ternopil
«Ukrmedknyga», 2004.-364 p.
Б. Adding:
1. The Merck Manual of Diagnosis and Therapy.-Merck Sharp, 1987.-2696 p.
2. Reese R.E. A Practical Approach to Infectious Diseases-Boston-Toronto: Little,
Brown&Company, 1986.-782 p.
3. Ellner P.D., Neu H.C. Understanding Infectious Diseases – Mosby Year Book,
1992.- 343 p.