Parasit Flashcards
Giardia Interstinalis Diagnosis
- cysts in the faeces -duodenal fluid/ biopsy may demonstrate trophozoites
- ELISA and IF
Trichomonas vaginalis Diagnosis
-microscopic examination of genital secretions
Trypanosoma brucei gambiense Diagnosis
-examination of lymph node aspirates blood, bone marrow, or in late stage- CSF
Leishmania donovani Diagnosis
- identification of amastigote in tissue (bone marrow, liver, spleen, lymph nodes, blood)
- PCR
Leishmania Tropica Diagnosis
- skin test and detection of anti-leishmanial antibodies by immune- fluorescence
- PCR
Entamoeba histolytica Diagnosis
- finding trophozoites & cyst in stool
- EIA
- PCR (for comparative analysis)
Ancantamoeba spp Diagnosis
-examination of brain tissue, skin, cornea
examination of CSF -PCR-based techniques
Naegleri flowleri Diagnosis
-examination of CSF and tissue
Plasmodium spp. Host
Definitive Host: female mosquito Intermediate Host: human
1. Sporogony- female mosquito (sexual cycle) 2. Schizogony- human (asexual cycle)
Toxoplasma Gondii Host
Definitive Host: human Intermediate Host: cat
Cryptosporidium Parvum Host
Definitive Host: contaminated water Intermediate Host: human
Giardia Interstinalis Clinical Features
Acute giardiasis:
Incubation 5-6 days & last for 1-3 weeks Symptoms: diarrhea, abdominal pain, bloating, nausea, vomiting.
Chronic giardiasis: Symptoms are recurrent & malabsorption & debilitation may occur
Trichomonas vaginalis Clinical Features
In women symptomatic:
-vaginitis w. purulent discharge, small hemorrhagic spots, vaginal pH above 5, ab pain, dysuria & dyspareunia, pain when sex
In male asymptomatic: -urethral discharge, pain during urination, mild itching and burning after sex, prostatitis
Trypanosoma brucei gambiense Clinical Features
African sleeping
sickness: 3 stages -early phase > fever, headache, joint pain & itching
-2nd phase > parasite crosses blood-brain barrier & infects CNS >symptoms: Confusion, sensory disturbances, poor coordination, disturbance of sleep cycle> coma
No treatment>fatal
Leishmania donovani Clinical Features
2 main forms of disease: 1! cutaneous 2!visceral (kala-azar) Visceral Leishmaniasis: -incubation period varies, 1-2 weeks up to several -fever
- weight loss
- enlarged spleen & liver -some have swollen glands -blood tests are abnormal (low blood counts) -important opportunistic infection in areas where it coexists with HIV
Leishmania Tropica Clinical Features
Cutaneus Leishmaniasis:
1 or more cutaneus lesions on areas from flybit. Look like volcano & can be painful or painless. Swollen glands near the sore
Entamoeba histolytica Clinical Features
Intestinal Amoebiasis
-may be asymptomatic
-ab pain, diarrhea, malaise, weight loss
-appendicitis
-dysentery
Extraintestinal Amoebiasis Secrete histolysin > help to invade submucosal tissue -invade RBC
-can be carried to liver> hepatic amoebiasis/ hepatitis -secondary!other organs may be invaded
Ancantamoeba spp Clinical Features
-granulomatous amebic encephalitis (GAE)! especially in individuals with compromised immune systems -ocular keratitis! infecting wearers of soft contact lenses- amoeba can survive in the space between the lens and the eye
Naegleri flowleri Clinical Features
-Acute primary amebic meningoencephalitis (PAM) it presents with severe headache and other meningeal signs, fever, vomiting
Giardia Interstinalis Life Cycle
- ingestion of cysts from water or food
- in small intestine>excystation> releasing trophozoites (each cyst produces 2)> multiply (longitudinal binary fission) -encystation when moving down colon -cyst in faeces
Trichomonas vaginalis Life Cycle
- resides in female genital tract or male urethra & prostate
- binary fission
- transmitted by sexual intercourse (humans are the only known host)
Trypanosoma brucei gambiense Life Cycle
- Parasite ingested by tsetsefly when taking a bloodmeal.
- multiply in fly in gut & salivary glands -Takes 3 weeks
- next bloodmeal> ing est metacyclic trypomastigotes in humans
- multiplies by binary fission
Leishmania donovani Life Cycle
-ingestion by vector of amastigote> becomes promastigote in gut, multiply by longitudinal
binary fission
-sandfly introduces promastigote in human blood when it bites -macrophages engulf the promastigote > revert to intracellular amastigote -reproduction of amastigotes by longitudinal binary fission
Leishmania Tropica Life Cycle
-ingestion by vector of amastigote> becomes promastigote in gut, multiply by longitudinal
binary fission
-sandfly introduces promastigote in human blood when it bites -macrophages engulf the promastigote > revert to intracellular amastigote -reproduction of amastigotes by longitudinal binary fission
Entamoeba histolytica Life Cycle
- excystation in small intestine > release trophozoites > migrate to large intestine
- multiply > binary fission > produce cysts (encystation) -both stages are passed in the faeces
Ancantamoeba spp Life Cycle
- found in soil; fresh, brackish, and sea water; sewage…
- replicate by mitosis (trophozoites are infective stage)
- believed to enter the body through lower respiratory tract, ulcerated skin and invade CNS -cysts and trophozoites are found in tissue
Naegleri flowleri Life Cycle
- has three stages, cysts, trophozoites, & flagellated forms
- the trophozoites replicate by promitosis
- found in fresh water, soil…
- Trophozoites infect humans by entering olfactory neuroepithelium & reaching the brain! where inflammation occurs = death
Plasmodium spp. Life Cycle
Human- Schizogony
1. exoerythrocytic schizogony
-parasites undergoes asexual multiplication in the liver
-inside hepatocyte, sporozoite develops into trophozoite
-after 1-2 weeks, trophozoite nucleus divides, followed by division of the cytoplasm -thousands of merozoites produced!rupture from cell!enter blood circulation! invade red blood cells
2. erythrocytic schizogony
-inside erythrocyte, the merozoite grows to the early trophozoite stage- the signet ring stage
-this form develops into the mature trophozoite stage!undergoes multiple fission into schizonts!produces a new generation of merozoites in each erythrocyte (gametocytes)
Mosquito- Sporogony
-mosquitos ingest gameotocytes during blood meal!undergo a sporogonic cycle yielding sporozoites
- in p.vivax and p.ovale, a dormant stage (hypnozoites) can persist in the liver!causes relapses weeks/ years later
Toxoplasma Gondii Life Cycle
-oocysts are only present in the definitive host!passed in faeces!ingested by humans and other intermediate hosts
-oocysts develop into tachyzoites (rapidly multiplying trophozoite form of t.gondii)
-they divide rapidly in cells, causing tissue destruction and spreading the infection
-tachyzoites localize to muscle tissues and the CNS where they convert to tissue cysts, or bradyzoites
!animal-to-human (zoonotic) transmission !foodbourne transmission !mother-to-child (congenital) transmission
Cryptosporidium Parvum Life Cycle
- c.parvum and c.hominis occur in humans -cryptosporidium is found in soil, food, water, or surfaces that have been contaminated with infected human or animal faeces
- a person becomes infected by swallowing cryptosporidium parasites
- cryptosporidium lives in the intestine of infected humans or animals
transmission: -person to person -animal to human -foodbourne -waterbourne - has three stages, cysts, trophozoites, & flagellated forms
- the trophozoites replicate by promitosis
- found in fresh water, soil…
- Trophozoites infect humans by entering olfactory neuroepithelium & reaching the brain! where inflammation occurs = death
Plasmodium spp. Clinical Features
Incubation Period: 7-30 days Shorter periods!p.falciparum Longer periods!p.malariae
Most frequent symptoms: -fever and chills, sweats -headache
-myalgias, arthralgias -weakness
-nausea and vomiting -splenomegaly
-anemia, thrombocytopenia
“Cold” Stage: 15-60min, cold, shivering “Hot” Stage: 2-6hrs, fever, headaches, vomiting
“Sweating” Stage: 2-4hrs, sweats, temp to normal
P.falciparum:
-infections caused by seveer, potentially fatal forms:
-CNS involvement (cerebral malaria) -acute renal failure
-severe anemia
-respiratory distress syndrome -hemoglobinuria
cerebral malaria
-parasitized RBCs in brain vessels -freq. leads to death
-microvascular obstruction by thrombus formation
-disseminated coagulation -coma!poor oxygen delivery to brain
Plasmodium spp. Laboratory Diagnosis
- microscopic identification of gametocytes, merozoites, schizonts
- comparison of plasmodium species
- molecular diagnosis techniques can complement microscopy, especially in species identification ! PCR
- people with sickle cell anemia cannot get malaria, therefore frequencies of sickle cell carriers are high in malaria-endemic areas
- no vaccine against malaria is available
Toxoplasma Gondii Clinical Features
-acquired infection is generally asymptomatic -10%-20% of patients with acute infection may:
-develop cervical lymphadenopathy
-and/or a flu-like illness
-the clinical course is benign and self-limited
-symptoms usually resolve within a few months to a year Acute
-parasitic invasion of the mesenteric lymph nodes & liver
-painful, swollen, lymph glands in the inguinal, cervical, and subclavicular regions
-fever, headache, anemia, muscle pain
Congenital
-results from fetal transplacental infection
-12% of infected infants born alive die shortly after birth -abnormalities occur in the CNS, eyes, and viscera
Toxoplasma Gondii Laboratory Diagnosis
- serologic testing!antibody detection
- observation of parasites in patient specimens, such as bronchoalveolar lavage material or lymph node biopsy -detection of parasite genetic material by PCR, especially in detecting congenital infections in utero
Cryptosporidium Parvum Clinical Features
Cryptosporidiosis
-some people will have no symptoms at all -most common symptom is watery diarrhea
Other symptoms: -stomach cramps or pain -dehydration
-nausea
-vomiting
-fever
-weight loss
Cryptosporidium Parvum Laboratory Diagnosis
- microscopic diagnosis- oocysts in the stool -ELISA- antigen in the stool -immunofluorescence assay
- molecular methods
