Tissue parasites

LEISHMANIA
4/9/2020
prof. Mahi Ghobashy

4/9/2020
prof. Mahi Ghobashy

دورة حياة الليشمانيا
4/9/2020
prof. Mahi Ghobashy

Clinical Features:
Human leishmanial infections can result in 2 main forms of disease, cutaneous leishmaniasis and visceral leishmaniasis (kala-azar). The factors determining the form of disease include leishmanial species, geographic location, and immune response of the host. Cutaneous leishmaniasis is characterized by one or more cutaneous lesions on areas where sandflies have fed. Persons who have cutaneous leishmaniasis have one or more sores on their skin. The sores can change in size and appearance over time. They often end up looking somewhat like a volcano, with a raised edge and central crater. A scab covers some sores. The sores can be painless or painful. Some people have swollen glands near the sores (for example, in the armpit if the sores are on the arm or hand).
Laboratory Diagnosis:
Examination of Giemsa stained slides of the relevant tissue is still the technique most commonly used to detect the parasite.
Diagnostic findings
Microscopy
Isolation of the organism in culture (using for example the diphasic NNN medium) or in experimental animals (hamsters) constitutes another method of parasitilogic confirmation of the diagnosis, and in addition can provide material for further investigations (e.g., isoenzyme analysis).
Antibody detection can prove useful in visceral leishmaniasis but is of limited value in cutaneous disease, where most patients do not develop a significant antibody response
molecular (PCR) approaches. Such techniques, however, are not readily available in general diagnostic laboratories.
4/9/2020
prof. Mahi Ghobashy

TOXOPLASMA GONDII
Causal Agent:
Toxoplasma gondii that infects most species of warm blooded animals, including humans, . A single-celled parasite (a protozoan parasite ) causes a disease known as toxoplasmosis. While the parasite is found throughout the world, more than 60 million people in the United States may be infected with the Toxoplasma parasite. Of those who are infected, very few have symptoms because a healthy person's immune system usually keeps the parasite from causing illness. However, pregnant women and individuals who have compromised immune systems should be cautious; for them, aToxoplasma infection could cause serious health problems.
Geographic Distribution:
Serologic prevalence data indicate that toxoplasmosis is one of the most common of humans infections throughout the world. A high prevalence of infection in France has been related to a preference for eating raw or undercooked meat, while a high prevalence in Central America has been related to the frequency of stray cats in a climate favoring survival of oocysts and soil exposure. The overall seroprevalence in the United States among adolescents and adults, as determined with specimens collected by the third National Health and Nutrition Examination Survey (NHANES III) between 1988 and 1994, was found to be 22.5%, with a seroprevalence among women of childbearing age (15 to 44 years) of 15%.
4/9/2020
prof. Mahi Ghobashy

Definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives).
Unsporulated oocysts are shed in the cat’s feces . Although oocysts are usually only shed for 1-2 weeks, large numbers may be shed. Oocysts take 1-5 days to sporulate in the environment and become infective. Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts .
Oocysts transform into tachyzoites shortly after ingestion. These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites . Cats become infected after consuming intermediate hosts harboring tissue cysts . Cats may also become infected directly by ingestion of sporulated oocysts.
Animals bred for human consumption and wild game may also become infected with tissue cysts after ingestion of sporulated oocysts in the environment . Humans can become infected by any of several routes:

4/9/2020
prof. Mahi Ghobashy

In the human host, the parasites form tissue cysts, most commonly in skeletal muscle, myocardium, brain, and eyes; these cysts may remain throughout the life of the host
Healthy people (nonpregnant)
Healthy people who become infected with Toxoplasma gondii often do not have symptoms because their immune system usually keeps the parasite from causing illness. When illness occurs, it is usually mild with "flu-like" symptoms (e.g., tender lymph nodes, muscle aches, etc.) that last for weeks to months and then go away. However, the parasite remains in their body in an inactive state. It can become reactivated if the person becomes immunosuppressed.
Mother-to-child (congenital)
Generally if a woman has been infected before becoming pregnant, the unborn child will be protected because the mother has developed immunity. If a woman is pregnant and becomes newly infected with Toxoplasma during or just before pregnancy, she can pass the infection to her unborn baby (congenital transmission). The damage to the unborn child is often more severe the earlier in pregnancy the transmission occurs. Potential results can be
a miscarriage
a stillborn child
a child born with signs of toxoplasmosis (e.g., abnormal enlargement or smallness of the head)
Infants infected before birth often show no symptoms at birth but may develop them later in life with potential vision loss, mental disability, and seizures.
4/9/2020
prof. Mahi Ghobashy
How can Toxoplasma affect my unborn child?
If you are newly infected with Toxoplasma while you are pregnant, or just before pregnancy, then you can pass the infection on to your baby. You may not have any symptoms from the infection. Most infected infants do not have symptoms at birth but can develop serious symptoms later in life, such as blindness or mental disability. Occasionally infected newborns have serious eye or brain damage at birth

Laboratory Diagnosis:
The diagnosis of toxoplasmosis may be documented by:
Observation of parasites in patient specimens, such as bronchoalveolar lavage material from immunocompromised patients, or lymph node biopsy.
Diagnosis
A Toxoplasma-positive reaction, stained by immunofluroescence (IFA). (CDC Photo)
The diagnosis of toxoplasmosis is typically made by serologictesting. A test that measures immunoglobulin G (IgG) is used to determine if a person has been infected. If it is necessary to try to estimate the time of infection, which is of particular importance for pregnant women, a test which measures immunoglobulin M (IgM) is also used along with other tests such as an avidity test.
Diagnosis can be made by direct observation of the parasite in stained tissue sections, cerebrospinal fluid (CSF), or other biopsy material. These techniques are used less frequently because of the difficulty of obtaining these specimens.
Parasites can also be isolated from blood or other body fluids (for example, CSF) but this process can be difficult and requires considerable time.
Molecular techniques that can detect the parasite's DNA in the amniotic fluid can be useful in cases of possible mother-to-child (congenital) transmission.
Isolation of parasites from blood or other body fluids, by intraperitoneal inoculation into mice or tissue culture. The mice should be tested for the presence of Toxoplasma organisms in the peritoneal fluid 6 to 10 days post inoculation; if no organisms are found, serology can be performed on the animals 4 to 6 weeks post inoculation.
Detection of parasite genetic material by PCR, especially in detecting congenital infections in utero.
Serologic testing is the routine method of diagnosis.
Diagnostic findings Microscopy
Antibody detection
4/9/2020
prof. Mahi Ghobashy

Paragonimus westermani is the major species of lung fluke that infects humans, causing paragonimiasis. The species sometimes is called the Japanese lung fluke or oriental lung fluke. Human infections are most common in eastern Asia and in South America.
Paragonimus westermani

clonorchis sinensis

DRACUNCULUS MEDINENSIS
4/16/2020
prof. Mahi Ghobashy