Protozoa & parasites (Med Micro 2) Flashcards
(117 cards)
1
Q
What are protozoa?
A
Motile, unicellular, eukaryote.
2
Q
What is a trophozoite?
A
Metabolically active, feeding, and motile stage in the life cycle of certain protozoa.
3
Q
Name three gut protozoa.
A
- Giardia intestinalis
- Entamoeba histolytica
- Cryptosporidium spp.
4
Q
What are the two forms of Giardia?
A
- Trophozoite (motile, in small intestine)
- Cyst (infectious form)
5
Q
What is the transmission method for Giardia?
A
Ingestion of cysts from contaminated water, food, or direct contact.
6
Q
What are the clinical features of Giardia infection?
A
- Incubation: 1–2 weeks
- Watery diarrhoea
- Bloating, flatulence
- Steatorrhoea (malabsorption)
- Chronic cases → weight loss, fatigue
7
Q
What diagnostic methods are used for Giardia?
A
- Stool microscopy (3 samples preferred)
- Antigen detection (ELISA)
- PCR (if available)
8
Q
What is the first-line treatment for Giardia?
A
- Tinidazole 2g STAT
- Metronidazole 5–7 days
9
Q
What is post-giardia syndrome?
A
IBS type symptoms following eradication of the organism.
10
Q
What is Entamoeba histolytica known for?
A
Endemic in areas with poor sanitation.
11
Q
How is Entamoeba histolytica transmitted?
A
Faeco-oral route; ingested cysts become trophozoites.
12
Q
What are common clinical features of Entamoeba histolytica?
A
- Asymptomatic colonisation
- Amoebic dysentery: diarrhoea, abdominal pain
- Liver abscess: fever, RUQ pain, hepatomegaly
13
Q
What diagnostic methods are used for Entamoeba histolytica?
A
- Stool microscopy
- Stool antigen detection
- PCR
- Serology (useful in liver abscess)
- Imaging (US/CT) for abscess
14
Q
What is the treatment for Entamoeba histolytica?
A
Metronidazole followed by a luminal agent like paromomycin.
15
Q
What is Cryptosporidium?
A
Small intracellular protozoan; forms oocysts; resistant to chlorination.
16
Q
How is Cryptosporidium transmitted?
A
Ingestion of oocysts from contaminated water or food.
17
Q
What are the clinical features of Cryptosporidium in immunocompromised patients?
A
Severe, chronic diarrhoea, weight loss, biliary and respiratory tract involvement.
18
Q
What diagnostic method is used for Cryptosporidium?
A
Modified acid-fast stain of stool.
19
Q
What is the treatment for Cryptosporidium?
A
Supportive care; nitazoxanide effective in immunocompetent.
20
Q
What is an oocyst?
A
A specialized, zygote-containing structure formed after sexual reproduction
21
Q
Name two protozoan blood infections.
A
- Malaria (Plasmodium spp)
- African Trypanosoma - African Sleeping Sickness (Trypanosoma brucei)
22
Q
What are the common symptoms of malaria?
A
- Fever
- Chills
- Headache
- Flu-like illness
23
Q
What severe symptoms can malaria lead to?
A
- Organ damage
- Seizures
- Coma
- Death
24
Q
What is the geographic distribution of malaria?
A
Tropical and subtropical regions, particularly in Africa and Asia.
25
What diagnostic methods are available for malaria?
* Rapid diagnostic tests
* Microscopic examination of blood smear - thick AND thin smear
26
What is the most effective treatment for malaria?
Artemisinin-based combination therapy (ACT)
27
What are the clinical features of severe malaria according to WHO?
* Impaired consciousness
* Prostration
* Multiple convulsions
* Deep breathing and respiratory distress
* Acute pulmonary oedema
* Circulatory collapse or shock
* Acute kidney injury
* Clinical jaundice plus other vital organ dysfunction
* Abnormal bleeding
28
What does the mnemonic 'Some People Like Bloody Mangoes And Red Guavas' stand for?
* S – Sporozoites
* P – Pre-erythrocytic stage
* L – Liver rupture
* B – Blood stage
* M – Merozoites re-enter new RBCs
* A – Asexual cycle
* R – Ring forms
* G – Gametocytes
29
When should you repeat a malaria blood smear?
Clinical suspicion of malaria and initial negative smear - repeat every 12–24 hours until positive, or until three tests are negative.
30
What are the five species of Plasmodium that cause malaria?
P. falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi
## Footnote
Each species has distinct characteristics and geographic distributions.
31
What is the severity of P. vivax infections?
Generally benign, relapses possible
## Footnote
While typically less severe, relapses can occur due to hypnozoites.
32
Which Plasmodium species can cause multi-organ failure?
P. falciparum
## Footnote
This is the most severe form of malaria.
33
What are common complications associated with P. falciparum?
* Cerebral malaria
* Renal failure
* ARDS
* Severe anemia
## Footnote
These complications highlight the severity of infections caused by this species.
34
What is the incubation period for P. malariae?
18-40 days
## Footnote
This longer incubation period can delay the onset of symptoms.
35
Which species of Plasmodium has a 72-hour (quartan) fever periodicity?
P. malariae
## Footnote
This periodicity is distinctive among malaria-causing species.
36
What peripheral blood findings are associated with P. falciparum?
High parasitemia, banana-shaped gametocytes
## Footnote
These findings are critical for diagnosis.
37
True or False: P. ovale infections are generally benign but can relapse.
True
## Footnote
Similar to P. vivax, P. ovale can also cause relapses due to liver stages.
38
Fill in the blank: The incubation period for P. knowlesi is _______.
9-12 days
## Footnote
This relatively short incubation period can lead to a quick onset of symptoms.
39
What are the common complications associated with P. vivax?
* Splenomegaly
* Anemia
## Footnote
These complications, while less severe, can still impact patient health.
40
What is the lab criteria for severe malaria according to WHO?
| Different countries have their own criteria.
Any of the following:
* Hyperparasitemia >10%
* Severe anemia
* Hypoglycemia
* Acidosis
* Renal failure
* Hyperlactatemia
* Hyperbilirubinemia
## Footnote
Specific values: Hyperparasitemia ≥10% of red blood cells parasitized; Severe anemia Hemoglobin < 5 g/dL; Hypoglycemia Blood glucose < 2.2 mmol/L; Acidosis Plasma bicarbonate < 15 mmol/L or lactate > 5 mmol/L; Renal failure Serum creatinine > 265 µmol/L; Hyperlactatemia Lactate > 5 mmol/L; Hyperbilirubinemia Total bilirubin > 50 µmol/L with parasiteemia.
41
Which RBC stage is affected in P. falciparum infection?
All stages (young and mature)
## Footnote
P. falciparum can infect both young and mature red blood cells.
42
Which RBC stage is affected in P. vivax infection?
Young RBCs (reticulocytes)
## Footnote
P. vivax specifically targets reticulocytes.
43
Which RBC stage is affected in P. ovale infection?
Young RBCs (reticulocytes)
## Footnote
Similar to P. vivax, P. ovale also affects reticulocytes.
44
Which RBC stage is affected in P. malariae infection?
Old/mature RBCs
## Footnote
P. malariae preferentially infects older red blood cells.
45
Which RBC stage is affected in P. knowlesi infection?
All stages (like P. falciparum)
## Footnote
P. knowlesi infects both young and mature red blood cells.
46
Why is severe malaria usually caused by P. falciparum?
Higher number of merozoite per hepatocyte and schizont, rapid multiplication, RBC age preference
## Footnote
P. falciparum has a higher capacity for infection and replication in red blood cells.
47
What is early treatment failure in malaria?
Parasite count on day 3 > day 1 of treatment; fever > 37.5 more than day 4 of treatment.
## Footnote
Early treatment failure indicates a lack of response to malaria treatment within the first few days.
48
What is late treatment failure?
Late clinical failure: fever >37.5 more than five days after treatment initiation; Late parasitological failure: fever and parasitaemia more than 8 days after parasite clearance.
## Footnote
Late treatment failure reflects issues that arise after the initial treatment period.
49
What is recrudescence in malaria?
Remaining blood stage parasites (all species but mostly P.falciparum) after treatment.
## Footnote
Recrudescence refers to the return of malaria symptoms due to surviving parasites after treatment.
50
What are the parasitological features of malaria relapse?
Results from maturation of persistent hypnozoite in liver (P.vivax and P.ovale).
## Footnote
Relapse occurs when dormant liver stages reactivate and cause infection after a period of quiescence.
51
Who is at greatest risk of recrudescence?
Children < 3 years; Immunocompromised; High parasitaemia.
## Footnote
These groups have a higher likelihood of experiencing recrudescence due to their immune status and parasite load.
52
What are HRP-II and pLDH used for?
Rapid diagnostic tests (RDTs) for malaria
## Footnote
Both antigens are crucial for diagnosing malaria infections.
53
Fill in the blank: HRP-II detects _______.
Plasmodium falciparum
54
Fill in the blank: pLDH detects _______.
all Plasmodium species or species-specific pLDH
55
What is the fever periodicity for P.falciparum?
Irregular
## Footnote
Irregular fever does not follow a consistent pattern.
56
What is the fever periodicity for P.vivax and P.ovale?
48-hour (tertian)
## Footnote
Tertian fever occurs every 48 hours.
57
What is the fever periodicity for P.malariae?
72-hour (quartan)
## Footnote
Quartan fever occurs every 72 hours.
58
What is the fever periodicity for P.knowlesi?
24-hour (quotidian)
## Footnote
Quotidian fever occurs daily, every 24 hours.
59
What causes relapses in P. vivax?
Hypnozoites in the liver
60
Which therapies are effective against hypnozoites in P. vivax?
Primaquine or tafenoquine
61
What are the species of malaria?
P. falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi
## Footnote
These are the main species responsible for malaria in humans.
62
What is the treatment for uncomplicated malaria caused by P. falciparum?
ACT (artemether-lumefantrine, artesunate + mefloquine)
## Footnote
ACT is the first-line treatment for uncomplicated P. falciparum malaria.
63
What is the treatment for uncomplicated malaria caused by P. vivax?
Chloroquine (if sensitive) or ACT
## Footnote
Primaquine is also required after G6PD testing.
64
What is the treatment for uncomplicated malaria caused by P. ovale?
Chloroquine (if sensitive) or ACT
## Footnote
Primaquine is also required after G6PD testing.
65
What is the treatment for uncomplicated malaria caused by P. malariae?
Chloroquine (or ACT if mixed infection)
## Footnote
There is no hypnozoite stage for P. malariae.
66
What is the treatment for uncomplicated malaria caused by P. knowlesi?
ACT (like P. falciparum)
## Footnote
Similar treatment protocols apply for this species.
67
What is the treatment for severe malaria?
IV artesunate → switch to ACT when stable
## Footnote
IV artesunate is the preferred treatment for severe cases.
68
Name three types of malaria vaccine
* Pre-erythrocytic vaccines (sporozoite stage)
* Asexual blood-stage vaccines (merozoite stage)
* Transmission blocking vaccines (Gametocyte stage)
69
What are the main features of Cutaneous Leishmaniasis (CL)?
Skin ulcers, nodules, painless sores; may scar permanently
## Footnote
Common in Middle East, North Africa, Latin America, Central Asia
70
What are the symptoms of Visceral Leishmaniasis (VL, kala-azar)?
Fever, weight loss, hepatosplenomegaly, anemia; fatal if untreated
## Footnote
Common regions include South Asia, East Africa, Brazil
71
Which regions are common for Cutaneous Leishmaniasis (CL)?
Middle East, North Africa, Latin America, Central Asia
## Footnote
This disease can lead to permanent scarring.
72
What is the initial presentation of Cutaneous Leishmaniasis?
Begins as a papule that enlarges and ulcerates
## Footnote
May heal spontaneously but often leaves scars
73
What are the symptoms of Mucocutaneous Leishmaniasis?
Nasal congestion, bleeding, facial disfigurement
## Footnote
Progresses from prior cutaneous lesions, especially L. braziliensis
74
What is a potential outcome of untreated Visceral Leishmaniasis?
May lead to death
## Footnote
Treatment is crucial to prevent fatality
75
What is the first-line treatment for Visceral Leishmaniasis in India?
Liposomal amphotericin B
## Footnote
This treatment is particularly emphasized for its effectiveness in the Indian context.
76
What is the local therapy recommended for mild Cutaneous Leishmaniasis?
Cryotherapy, topical paromomycin
## Footnote
These treatments are aimed at localized lesions.
77
What is the systemic therapy for Mucocutaneous Leishmaniasis or severe Cutaneous Leishmaniasis?
(liposomal) Amphotericin B
## Footnote
Systemic therapy is necessary for more severe manifestations of leishmaniasis.
78
What is the case definition of visceral leishmaniasis?
Temperatureº>38ºC for 2 weeks (bacterial infections excluded) + splenomegaly + positive rK39 (RDT)
## Footnote
This indicates a persistent fever that helps distinguish visceral leishmaniasis from other conditions.
79
What is a key symptom of visceral leishmaniasis besides fever?
Splenomegaly
## Footnote
This refers to the enlargement of the spleen, which is a common clinical finding in visceral leishmaniasis.
80
What are common side effects of liposomal amphotericin B?
Vomiting, chills, hypokalaemia
## Footnote
These side effects can impact patient tolerance and treatment adherence.
81
Why is amphotericin B preferred over other formulations?
It is well tolerated and better at infiltrating immune cells but it is more expensive
## Footnote
This makes it a favored choice despite the cost.
82
What factors influence the treatment of cutaneous leishmaniasis?
Clinical features and potential to develop to mucocutaneous leishmaniasis
## Footnote
Treatment may vary based on severity and risk of complications.
83
What is the most common form of leishmaniasis?
Cutaneous leishmaniasis
## Footnote
It presents with skin lesions and is widespread in endemic areas.
84
When do sandflies typically bite?
In early morning and evening
## Footnote
Understanding sandfly behavior can aid in prevention strategies.
85
What is a primary prevention method against leishmaniasis?
Avoiding sandfly bites; avoiding rural areas, DEET and insect repellents
## Footnote
Effective use of repellents can significantly reduce risk.
86
Which species causes visceral leishmaniasis?
Leishmania donovani
## Footnote
This species is associated with severe systemic disease.
87
Name the four species causing mucocutaneous leishmaniasis.
* Leishmania braziliensis,
* Leishmania panamensis,
* Leishmania guyanensis,
* Leishmania amazonensis
## Footnote
Each species has unique epidemiological and clinical implications.
88
What are the features of complicated leishmaniasis?
* >4 lesions
* MCL potential
* Immunocompromised
* >4 months of treatment and not improving,
* lesion >4cm
* lesion on face/fingers/toes/genitals
## Footnote
MCL stands for mucocutaneous leishmaniasis, which can occur in severe cases of leishmaniasis.
89
Where should you obtain a biopsy of cutaneous leishmaniasis?
Edge of lesion
## Footnote
Biopsy is crucial for accurate diagnosis and should be taken from the lesion's edge.
90
What is the diagnosis method for MCL?
NAAT
## Footnote
NAAT (nucleic acid amplification testing) is preferred as it is difficult to see organisms on biopsy or culture.
91
Why is it challenging to biopsy mucosal areas in MCL diagnosis?
Difficult to biopsy mucosal areas
## Footnote
Mucosal areas are often difficult to access and sample effectively.
92
What is the treatment for uncomplicated cutaneous leishmaniasis (CL)?
Leave it, local therapy - thermotherapy/cryotherapy, paromycin ointment
## Footnote
Uncomplicated CL often self-resolves, and local treatments can aid recovery.
93
When does Post-Kala-Azar Dermal Leishmaniasis (PKDL) typically occur after treatment for visceral leishmaniasis?
6 months (Sudan) to 1–2 years (India)
## Footnote
PKDL is a dermal manifestation that can appear after successful treatment of visceral leishmaniasis.
94
Where is CL usually found?
Middle east, north africa
95
Where is VL normally found?
Laterin america, mediterranean, SE asia
96
Where is MCL usually found?
South america
97
Name some important causes of childhood diarrhoea
* rotavirus
* Cryptosporidium spp
* norovirus
* adenovirus
98
What are the primary causes of acute bloody diarrhoea?
* shigellosis
* salmonellosis
99
What is the primary mode of transmission in Chagas endemic areas?
Via kissing bug bites
100
List modes of transmission for Chagas disease, other than via kissing bug bites.
* Ingestion of contaminated acai berries
* Blood transfusion/organ transplantation without prior testing
* Congenital spread
101
What is the commonest route of transmission for Chagas in non-endemic settings?
Mother-to-child spread
102
What are the major causes of visceral leishmaniasis worldwide?
* L. infantum
* L. donovani
103
How do humans acquire Ascaris infection?
By ingesting embryonated eggs
104
What is Loffler’s syndrome?
Eosinophilic pneumonia caused by Ascaris larvae migrating to the lungs
105
What is the life cycle of Ascaris after ingestion?
* Larvae hatch in the small intestine
* Migrate to the lungs
* Coughed up and re-enter gastrointestinal tract
* Mature into adult forms
* Produce eggs passed via faeces into soil
106
What causes neurocysticercosis?
Larval cysts of Taenia solium migrated to the brain.
107
What are the two forms caused by Taenia solium?
* Cysticercosis (larval form)
* Taeniasis (adult form)
108
How does cysticercosis develop in humans?
By consuming food/water contaminated with eggs of Taenia solium
109
What triggers seizures in cysticercosis?
Localized inflammatory reaction from dying larvae
110
When are microfilariae of loa loa most active?
During the day, around noon
111
When are microfilariae of Wuchereria bancrofti and Brugia malayi most active?
At night
112
What is the most common presentation of intestinal amoebiasis?
Asymptomatic
113
What is the investigation of choice for onchocerciasis?
Skin snips for microscopy
## Footnote
Adult filariae found in skin nodules.
114
What can be used to identify microfilariae in the eye for those with eye disease?
Slit lamp examination
115
What are the symptoms of onchocerciasis?
* Intense pruritis
* Patchy depigmentation
* Inguinal lymphadenopathy
* Nodules on hips and knees
116
When does Katayama fever typically develop after acquiring schistosomiasis?
6 weeks
117
What is the treatment of choice for acute schistosomiasis?
Praziquantel
