OPTO435 Microbiology II Gamal El-Hiti

1. OPTO435 Microbiology II Gamal El-Hiti

2. Protozoa Lecture Eight

3. Learning Outcomes OPT435 L08 – W10

4. Protozoa  Protozoa are a diverse group of unicellular organisms that was introduced in 1818.  They defined as single-celled organisms with animal-like behaviors.  Reproduction is generally by binary fission, although in some protozoal species, sexual reproduction occurs as well.  Only a few of the many tens of thousands of protozoan species are pathogenic and cause infections in human. OPT435 L08 – W10

5. Protozoa  These pathogens are of two general kinds.  Those that parasitize the intestinal and urogenital tracts.  Those that parasitize blood cells and tissues.  Protozoal infections are common in the developing tropical and subtropical regions. OPT435 L08 – W10

6. Protozoa OPT435 L08 – W10

7. Toxoplasma gondii  Toxoplasma gondiiis a single-celled parasite.  It can cause toxoplasmosis.  More than 60 million people in the US may be infected with the Toxoplasma parasite.  Very few infections lead to symptoms because the immune system usually prevents the parasite from causing illness.  Toxoplasma infection causes serious health problems for pregnant women and individuals with compromised immune systems. OPT435 L08 – W10

8. Toxoplasma gondii OPT435 L08 – W10

9. Toxoplasma gondii  Life cycle of Toxoplasma gondii  The only known definitive hosts for Toxoplasma gondiiare domestic cats.  Unsporulated oocysts are shed in the cat’s feces.  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. OPT435 L08 – W10

10. Toxoplasma gondii  These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites.  Cats become infected after consuming intermediate hosts harboring tissue cysts.  Animals bred for human consumption and wild game may also become infected with tissue cysts after ingestion of sporulated oocysts in the environment.  Human can become infected by any of several routes such as: OPT435 L08 – W10

11. Toxoplasma gondii  Eating undercooked meat of animals harboring tissue cysts.  Consuming food or water contaminated with cat feces.  Blood transfusion or organ transplantation.  Transplacentally from mother to fetus.  Diagnosis is usually achieved by serology.  Diagnosis of congenital infections can be achieved by detecting T. gondii DNA in amniotic fluid using molecular methods such as PCR. OPT435 L08 – W10

12. Toxoplasma gondii OPT435 L08 – W10

13. Toxoplasma gondii OPT435 L08 – W10

14. Toxoplasma gondii  Symptoms of toxoplasmosis  People who have toxoplasmosismay feel flu symptoms with swollen lymph glands or muscle aches and pains that last for a month.  Severe toxoplasmosis could cause damage to the brain, eyes or other organs.  Symptoms of ocular toxoplasmosis include blurred vision, pain, redness or tearing.  A small percentage of infected newborns have serious eye or brain damage at birth. OPT435 L08 – W10

15. Toxoplasma gondii  Treatment and prevention of toxoplasmosis  Once a diagnosis of toxoplasmosis is confirmed, treatment should be considered, if necessary.  In healthy woman who is not pregnant, treatment usually is not needed.  If symptoms occur, they typically go away within a few weeks to months.  For pregnant women or persons who have weakened immune systems, medications are available to treat toxoplasmosis.  OPT435 L08 – W10

16. Toxoplasma gondii  Risk factors for Toxoplasma  Cook food to safe temperatures (62–73 C).  Do not sample meat until it is cooked.  Freeze meat for several days before cooking greatly reduce chance of infection.  Peel or wash fruits and vegetables thoroughly before eating.  Do not eat raw or undercooked oysters or mussels contaminated with Toxoplasma.  Ensure the cat litter box is changed daily.  OPT435 L08 – W10

17. Toxoplasma gondii  Do not drink unpasteurized goat's milk.  Wash cutting boards, dishes and hands with hot soapy water after contact with raw meat that might be contaminated with Toxoplasma gondii. Wear gloves during any contact with soil or sand because it might be contaminated with cat feces that contain T. gondii.  Teach children the importance of washing their hands to prevent infection by T. gondii. OPT435 L08 – W10

18. Toxoplasma gondii OPT435 L08 – W10

19. Acanthamoeba  Acanthamoeba is a genus of amoebae.  Acanthamoeba is one of the most common protozoa in soil.  Frequently found in fresh water.  The cells are small, usually 15 to 35 μm in length and oval to triangular in shape when moving.  Acanthamoeba can form metabolically inactive cysts which are resistant to the changes in temperature and pH levels. OPT435 L08 – W10

20. Acanthamoeba  Life cycle of Acanthamoeba spp.  Acanthamoeba has only two stages, cysts and trophozoites, in its life cycle. OPT435 L08 – W10

21. Acanthamoeba  No flagellated stage exists as part of the life cycle.  The trophozoites replicate by mitosis (nuclear membrane does not remain intact).  The trophozoites are the infective forms, although both cysts and trophozoites gain entry into the body through various means.  Entry can occur through the eye, the nasal passages to the lower respiratory tract,   or ulcerated or broken skin. OPT435 L08 – W10

22. Acanthamoeba  When Acanthamoeba spp. enters the eye it can cause severe keratitis in otherwise healthy individuals, particularly contact lens users.  When it enters the respiratory system or through the skin, it can invade the CNS by hematogenous dissemination causing granulomatous amebic encephalitis (GAE) or disseminated disease, or skin lesions in individuals with compromised immune systems. OPT435 L08 – W10

23. Acanthamoeba OPT435 L08 – W10

24. Acanthamoeba  Advanced Acanthamoebakeratitis causes a white ring to cover the iris and redness in the white of the eye.  Although people who do not use contact lenses can also become infected. OPT435 L08 – W10

25. Acanthamoeba  Poor contact lens hygiene may increase the risk of Acanthamoeba entering the eye.  However, contact lens wearers who practice proper lens care can also develop infection.  Prevention is always the best approach, because Acanthamoeba keratitis can be extremely difficult to treat.  In fact, sometimes these infections require a corneal transplant, which is a serious surgical procedure. OPT435 L08 – W10

26. Acanthamoeba  Symptoms of Acanthamoeba keratitis  A red painful eye infection, especially if the discomfort does not improve with treatment.  Irritated eyes lasting for an unusually long period of time after removal of contact lenses.  Foreign body sensation  Tearing  Light sensitivity  Blurred vision OPT435 L08 – W10

27. Acanthamoeba  Risk factors of Acanthamoeba keratitis  Use of tap water in cleaning and disinfecting contact lenses.  Swimming with contact lenses in the eyes, especially in fresh water lakes and rivers. Acanthamoeba keratitis has also been isolated from virtually all water sources such as from pools to hot tubs to showers.  Failure to follow lens care instructions and poor compliance. OPT435 L08 – W10

28. Acanthamoeba  Lens care guide  Wash hands before handling contact lenses.  Rub and rinse the surface of the contact lens before storing.  Use only sterile products recommended by your optometrist.  Use fresh solution each time the lens is placed in the case.  Replace lenses in the prescribed schedule.  Never swap lenses with someone else. OPT435 L08 – W10

29. Acanthamoeba OPT435 L08 – W10

30. Demodex mites  Demodex mites and Blepharitis  Demodex is a genus of tiny parasitic mites usually does not cause any symptoms.  It lives on the domestic dogs.  Around 65 species of Demodex are know.  Two species have been identified in human as eyelash mites and blepharitis.  Treatment involves eyelid hygiene regimen.  Supplemental treatment with oral medicine may be required. OPT435 L08 – W10

31. Demodex mites OPT435 L08 – W10