Medical Parasitology Hugh B Fackrell Parasitic eukaryotes protozoa Platyhelminthes (flatworms)...
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Transcript of Medical Parasitology Hugh B Fackrell Parasitic eukaryotes protozoa Platyhelminthes (flatworms)...
Medical Parasitology
Hugh B Fackrell
Parasitic eukaryotes
protozoaPlatyhelminthes (flatworms)
Trematodes (flukes)Nematodes (roundworms)Cestodes (tapeworms)arthropods
protozoa:
most important in warmer climates do not elicit a strong antibody response
(some exceptions) diagnosed by microscopic means no vaccines humans are intermediate hosts
Protozoa - two forms
Trophozoite:
active, growing - causes disease
Cyst:
dormant, resistant form
- increases survival of protozoa and extends transmission
Intestinal & Urogenital Protozoa
Amebae Flagellates Ciliates Coccidia Microsporidia
Amebae
Sarcodina
Sarcodina: Entamoeba histolytica amoebiasis (amoebic dysentry).
only the cyst stage is infectious. disseminated amoebiasis - abscesses in the
liver, can be fatal, diagnosed serologically. person not infectious when gut contents
moving fast, cysts form when it slows down.
Sacrodina: treatment
tetracycline & diloxanide furoate. metronidazole. usually includes choloroquine.
Infections by Free Living Amaeboe
Naeglaria• Acathamoeba
Naegleria:
found in freshwater lakes or streams causes encephalitis in swimmers - can be
fatal (rare).
Acanthamoeba:
found in soil, fresh and brackish (1/2 salt) water
ubiquitous can infect contact lens not properly cared
for - infection of cornea, reduced vision. enucleation: complete removel of the
eyeball
Flagellates
Trichomoniasis: Trichomonas vaginalis - millions of cases sexually transmitted - trophozoite inhabits the
vagina and urethra. males have very little irritation. female, vagina becomes alkaline, allows the
bacteria to overgrow that are usually suppressed by acid - symptoms include odor, discharge, itching and burning.
Treatment: metronidazole, Flagyl.
Blood & Tissue Protozoa
Plasmodium Babesia Toxoplasma Sacrocystis Pneumocystis Leishmania Trypanosoma
Giardiasis: Giardia lamblia
fecal/oral transmission. the cyst form is very resistant to
destruction. infection of upper small instestine, can be
asymptomatic. most common protozoal infection in the
U.S.
Mastigophora: flagellates - con’t Gastroenteritis: diarrhea, dark, greasy, foul feces. abdomenal discomform, flatulence, anorexia, weight
loss. lasts two-three weeks followed by recovery. chronic - intermittent diarrhea. Transmission: water - treated and untreated. common in daycare centers
Trypanosomiasis:
Trypanosoma brucei gambiense (African sleeping sickness).
Trypanosoma brucei rhodesiense. South American sleeping sickness (T. cruzi). Chaga’s disease. reservoir in Africa: cattle, swine & wild animals. infected by the Tse Tse fly bite legion lymph
nodes - become lodged and form a chronic infection CNS - produce sleeping sickness coma.
Treatment: suramin sodium and pentamidine.
South American Sleeping Sickness T. cruzi: reservoir dogs, cats & wild animals. vector reduvid bugs - defecate when biting -
introduce trypanosomes. can be spread by hands from bite to eyes,
conjunctivitis. no treatment. Prevention: control insects.
Leishmaniasis: Sand flies
• a) cutaneous
• b) viscerotropuie (clinical note)
12 million cases fever, chills & sometimes gastrointestinal
involvement. bone marrow aspects - cultures also
serodiagnostic techniques.
Malaria Plasmodium vivax, P. falciparum and P. ovale. 100,000,000 cases spread by Anopheles mosquito 1 million deaths per year in the tropics and sub-tropics. life cycle of protozoa in the mosquito and the human control the transmission and the disease. infect red blood cells which burst - paroxysm chills, fever, headache, nausea and vomiting. Treatment: choloroquine & primaquine. prophylaxis in mosquito infested areas. Toxoplasmasis: Toxoplasma gondii world wide, very common domestic cats infected by eating mice, birds or raw meat and contact with the feces of other cats. not a serious illness - vague symptoms, fever, weakness, respiratory, mononucleosus-like lymphadenopathy
Pneumocystosis
Pneumocystis
Pneumocystis carinii - Thought to be a protozoan but recent RNA analysis has shown it to be a fungus.
Infections occur world wide, if symptoms occur - mild respiratory. Childhood.
Occurence Primarily AIDS Hospitalized infants who were premature and malnourished Elderly Cancer and organ transplant patients who are being treated with immunosuppressive drugs.
Pneumocystosis cont.
Respiratory Infection interstitial pneumonitis with plasma cell infiltrates
Treatment Trimethoprim - sulfamethoxazole Aerosolized pentamidine (particularly for AIDS patients)
Laboratory Diagnosis Sputum, lavage, Transbronchial aspirate, Brush biopsy, Open biopsy Microscopic - Stain appearance, Fluorescent antibody
Sporozoa Malaria: Plasmodium vivax, P. falciparum and P. ovale. 100,000,000 cases spread by Anopheles mosquito 1 million deaths per year in the tropics and sub-tropics. life cycle of protozoa in the mosquito and the human control the transmission and the disease. infect red blood cells which burst - paroxysm chills, fever, headache, nausea and vomiting. Treatment: choloroquine & primaquine. prophylaxis in mosquito infested areas. Toxoplasmosis: Toxoplasma gondii world wide, very common domestic cats infected by eating mice, birds or raw meat and contact with the feces of other cats. not a serious illness - vague symptoms, fever, weakness, respiratory, mononucleosus-like lymphadenopathy
Nematodes: Roundworms
Pinworm Roundworm Ascaris Whipworm Hookworm Threadworm etc
Coccidia
Cryptosporidiosis
Intestinal disease Zoonotic, and person-to-person
Cryptosporidium
- swallow oocyst- sporozoites released
- penetrate the brush border of intestine
mild self-limiting entercolitis watery diarrhea without blood.Remission - 10 days
High risk: veterinary personnel, homosexuals Immunocompromised - AIDS etc -50 stools per day
Coccidia cont.
Laboratory Diagnosis Fresh, or formalin-treated stool Microscopic - direct smear stain
- fluorescent antibody Oocysts - concentrated from stool of persons with diarrhea
Treatment Spiramycin in early stages of AIDS Restoration of fluid
Prevention Contaminated water supplies treated with chlorination and filtration avoid high risk sexual activities
flatworms (platyhelminthes)
arthropods
DONE!!!