Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 2 - MCD - Microbiology > 5 - Parasites (06.03.2020) > Flashcards

5 - Parasites (06.03.2020) Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Infection vs. Disease

A

Infection: invasion by and growth of
pathogenic microorganisms
within the body

Disease: a disordered or incorrectly functioning
organ, part, structure, or system of
the body resulting from the effect of
genetic or developmental errors,
infection, poisons, nutritional deficiency
or imbalance, toxicity, or unfavorable
environmental factors; illness;
sickness; ailment.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a parasite?

A

organism living in or on the host and dependent on it for nutrition - causing damage

-> the parasite utilises the host to survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Endoparasites

A

Protozoa: amoeba, coccidiae, ciliate, flagellates
Metazoa: roundworms, flatworms, flukes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 2 different types of parasites?

A
  • Endoparasites (Protozoa, Metazoa)

- Ectoparasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are protozoa?

A
  • single celled organisms
  • Eukaryotes (genome within a nucleus, complex organelles in cytoplasm)
  • Pathogenesis (mechanism of disease) varied
  • Some have insect vectors (eg malaria)
  • No eosinophilia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are metazoa?

A

Metazoa – Multicellular organisms (Helminths/worms)

  • Free living, intermediate hosts and vectors
  • Some just inhabit gut (geohelminths), other invade tissues
  • Eosinophilia – if invade blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

amoeba

A

the asymptomatic people keep the cycle going

cyst can remain viable for about 2 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do you diagnose entamoeba histolytic infections?

A
  • microscopically
  • look for the eggs in a faeces sample
  • wet mount
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Facts about Malaria

A
  • children are most at risk
  • In 2013, there were ~198 million cases of malaria, causing an estimated 584 000 deaths, mostly among African children (one child dies every 30 seconds).
  • 2 hosts: human and female anopheles mosquito
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Symptoms of malaria

A

Fever, headache, chills, vomiting, muscle pain
Paroxysm (cycle in 4-8hrs)

Can appear as early as 7 days but the time between exposure and signs of illness can be as long as one year.

  • 9 to 14 days for Plasmodium (P.) falciparum.
  • 12 to 18 days for P. vivax and P. ovale.
  • 18 to 40 days for P. malariae.
  • 11 to 12 days for P. knowlesi.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Complications of Malaria

A 
Severe anemia (destruction of red cells; go into red cells and the red cells burst)
Cerebral malaria (swelling of the brain,seizures, coma, death)
liver failure
Shock 
Pulmonary edema
abnormally low blood sugar 
kidney failure
swelling and rupturing of the spleen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Treatment of Malaria

A

Uncomplicated malaria:
chloroquine, Atovaquone-proguanil, Artemether-lumefantrine, quinine sulfate plus one of the following: Doxycycline, Tetracycline or Clindamycin Quinine sulfate, Mefloquine

Severe malaria:
Artemisinin-based combination therapy (ACT) is recommended for the treatment of P. falciparum malaria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Diagnosis of Malaria

A
  • blood film, Giemsa stained (H&E) - people have to be trained to do this
  • Rapid test: commercially available antigen detection tests: more expensive and less sensitive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Toxoplasmaa

A
  • Toxoplasmosis: mild disease in immunocompetent individuals: fever, swollen lymph nodes, headaches, sore throat.
  • however, in pregnancy: toxoplasmosis poses serious danger for the Foetus)
  • Immunocompromised patients may develop central nervous system disease, brain lesions, pneumonitis or retinochoroiditis among other risks.
  • cats and mice are intermediate hosts
  • infect warm blooded animals
  • there are serological tests
  • it is treatable

Infection:
• eating undercooked meat of animals harboring tissue cysts
• consuming food or water contaminated with cat feces
• by contaminated environmental samples
• blood transfusion
• organ transplantation
• transplacentally from mother to fetus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Flagellates examples and the disease they cause

A

Giardia lamblia (Giardiasis)

Disease: 
- symptoms dependent on dose
- most people are asymptomatic
- Acute symptoms: 
Diarrhea
Greasy stools that tend to float
Stomach or abdominal cramps
Upset stomach or nausea/vomiting
Dehydration (loss of fluids)

Diagnosis via stool sample, look for cysts and trophozoites (the 2 stages they are found in in humans)

Trichomonas

  • STI
  • symptoms in genital area in males and females however quite a proportion is asymptomatic
  • most common non viral STI in UK
  • infection enhances HIV transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Giardia lamblia (Giardiasis)

A
  • faeco-oral transmission
  • Giardiasis: commonest, globally distributed, water-borne protozoal infection.
  • Flagellated trophozooites attach by their suckers to surface of the duodenal or jejunal mucosa
  • Ovoid cysts are able to survive standard chlorination procedures, filtration is required to exclude them from drinking water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Giardia lamblia (Giardiasis) symptoms

A
  • dependent on parasite dose
  • Most people infected with Balantidium coli => no symptoms.
Acute symptoms: 
Diarrhea
Greasy stools that tend to float
Stomach or abdominal cramps
Upset stomach or nausea/vomiting
Dehydration (loss of fluids)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Giardia lamblia (Giardiasis) Diagnosis

A

Stool examination. (cysts, trophozoites)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Giardia lamblia (Giardiasis) - treatment

A

metronidazole/tinidazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Giardia lamblia (Giardiasis) - epidemiology

A

~2% of adults and 6% to 8% of children in developed countries worldwide; ~ 33% of people in developing countries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Examples of flagellates:

A
  • giardiasis
  • trichomoniasis
  • leishmania
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the difference between protozoa and metazoan?

A

Protozoa

  • are single celled organisms (genome within a nucleus, complex organelles in cytoplasm)
  • do not cause eosinophilia

Metazoa

  • are multicellular organisms (helminths/worms)
  • cause eosinophilia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are helminths?

A

Metozoa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the difference between endo- and ectoparasites?

A
  • endoparasites are inside the body

- ectoparasites affect the skin

25
Q

What are the 4 main types of protozoa?

A

amoebae
flagellates
ciliates
coccidia

26
Q

What are the 3 main types of metazoa/hemlinths?

A

flatworms
roundworms
flukes

27
Q

Name examples of amoeba and the disease they cause?

A
  • entamoeba dispar (commensal in gut)
  • entamoeba histolytica
  • 90% asymptomatic, in the 10% symptomatic:
  • causes a range of symptoms varying from dysentery to amoebic liver disease
  • can also affect the lungs, heart, skin, urinaray tract, brain
  • transmitted by ingestion if mature cysts in food, water ir on hands contaminated with faeces.
  • human - faeces - reingestion
28
Q

Name examples of coccidia and the disease they cause

A
  1. Plasmodium species - Malaria (headache, fever, chills, paroxysm, muscle pain, vomiting)
  2. Toxoplasma - Taxoplasmosis (mild in immunocompetent people (swollen lymph nodes, fever, headache, sore throat) but dangerous in immunocompromised and in pregnancies were it can cause damage in the foetus)
  3. Cryptosporidium - Diarrhoea, N&V, fever (mild disease in immunocompetent but can cause severe pathological changes in immunocompromised individuals); common in HIV+ presenting with diarrhoea; diagnose via stool sample, treat with fluids
29
Q

What is a paroxysm?

A

a sudden recurrence or attack of a disease.

“paroxysms of ataxia and shaking”

30
Q

Give an example of a ciliate and the disease it causes

A
  • Balantidium coli (Balantidiasis)
  • Most people infected are asymptomatic.
  • Immunocompromised patients may experience more severe signs and symptoms: persistent diarrhea, dysentery, abdominal pain, weight loss, nausea, and vomiting. If left untreated, perforation of the colon can occur.
  • worldwide distribution
  • reservoir hosts: pigs, rodents, primates
  • diagnosis via stool sample
  • treatable
31
Q

Dysentery

A
  • a type of gastroenteritis that results in diarrhea with blood.
  • Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation.
  • Complications may include dehydration.
  • The cause of dysentery is usually Shigella, in which case it is known as shigellosis, or Entamoeba histolytica.
32
Q

Trichomonas

A
  • In women the organism is found in the vagina, urethra and paraurethral glands; in men infection is usually of the urethra.

Symptoms

  • Females 10-50% are asymptomatic.=> vaginal discharge, vulval itching, dysuria, or offensive odour, but these are not specific for TV.
  • Occasionally the presenting complaint is of low abdominal discomfort or vulval ulceration.
  • Males 15 to 50% of men are asymptomatic => discharge and/or dysuria.

Complications: detrimental outcome on pregnancy and is associated with preterm delivery and low birth weight.

HIV
There is growing evidence that trichomonas infection may enhance HIV transmission and there may be an increased risk of TV infection in those that are HIV positive.

Diagnosis
Microscopy: Detection of motile trichomonads in swab/urine- Trichomonas Rapid Test

Treatment
metronidazole

33
Q

Exmamples of roundworms (nematodes)

A
  • ascaris
  • hookworm
  • Filaria
  • Strongyloides
34
Q

Ascariasis

A

Symptoms:

  • often causes no symptoms.
  • Infections with a large number of worms may cause abdominal pain or intestinal obstruction.
  • Adults feed on the contents of the SI and in heavy infections, this may compound problems in malnourished individuals (especially children).
  • Migration of larvae may cause localized reactions in various organs.
  • Penetration of the larvae from capillaries into the lungs can lead to Loeffler’s pneumonia, in which pools of blood and dead epithelial cells clog air spaces in the lungs.
  • Resulting bacterial infections can be fatal.
  • Diagnosis: stool sample
  • Treatment: albendazole and mebendazole
35
Q

Hookworm

A

Symptoms:

  • IDA
  • can be accompanied by cardiac symptoms
  • GI/nutritional.metabolic symptoms may occur
  • local skin manifestations
  • respiratory symptoms can be observed during pulmonary migration of the larvae.

Diagnosis:
Stool sample

Treatment:
albenazole and mebendazole

36
Q

Trichuris Trichiura - Whipworm

A
  • a hookworm
  • Small amounts of whipworms might not cause any symptoms.
  • But if there are hundreds of worms, then you might have bloody diarrhea and anemia due to severe vitamin and iron loss.
  • The worms leave open wounds, which cause inflammation of the intestinal wall.
  • In some cases you might also develop rectal prolapse.
  • Whipworm is one of the worms being used in helminthic therapy which helps against allergies and autoimmune diseases
  • Diagnosis: Stool sample
  • Treatment albendazole and mebendazole
37
Q

Lymphatic filariasis:

A
  • brugia malayi
  • wucheria bancrofti
    lymphatic obstruction (especially in the legs) can progress to elephantiasis – can also occur in arm, breast, scrotum

Diagnosis
The microfilariae are found mainly in the peripheral blood and can be found at peak amounts from 10 p.m. to 4 a.m. During the day, they are present in the deep veins, and during the night, they migrate to the peripheral circulation.
Blood smear or antigen detection with a immunochromatic test (card) or ELISA

Treatment: albendazole and ivermectin

38
Q

Filaria sybgroups

A

Filaria is a typeof roundworms which is a type of metazoan and includes:

  • lymphatic filariasis
  • loaloa (loasis)
39
Q

Loaloa

A
  • eye worm
  • confined in Africa
  • Infection with the parasite can also cause repeated episodes of itchy swellings of the body known as Calabar swellings
40
Q

Types of flatworms (cestodes)

A

Flatoworms = cetstodes

Humans are the only definitive hosts for

  • Taenia solium and T. asiatica – pig
  • T. saginata – beef
41
Q

Taenia

A

Symptoms:

  • Most people: no symptoms or mild symptoms.
  • Patients with T. saginata taeniasis often experience more symptoms (size of the worm up to 10m) that those with T. solium or T. asiatica (~3 m).
  • Tapeworms can cause digestive problems including abdominal pain, loss of appetite, weight loss, and upset stomach.
  • The most visible sign of taeniasis is the active passing of tapeworm segments

Diagnosis:
- Segment in stool or identifcation of eggs in stool

Treatment: praziquantel

Taenia solium - cysticercosis commonest cause of epilepsy worldwide

42
Q

What is the commonest acquired cause of epilepsy worldwide?

A

Taenia solium - cysticercosis

-> in the brain can cause epilepsy

43
Q

What is a type of fluke?

A

Schistosoma (mansion, haematobium, japonicum)

44
Q

Schistosoma

A

Symptoms

  • Within days: possible rash or itchy skin.
  • Within 1-2 months; fever, chills, cough, and muscle aches but most people have no symptoms at this early phase of infection.
  • When adult worms are present, the eggs that are produced usually travel to the intestine, liver or bladder, causing inflammation or scarring.
  • Children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties.
  • After years of infection, the parasite can also damage the liver, intestine, lungs, and bladder.

Diagnosis:
stool or urine samples

Treatment
praziquantel (now MDA in schools)

45
Q

Sarcoptes Scabei

A

Diagnostic
- Appearance of rash + presence of burrows

Treatment: Scabicides e.g. permethrin

46
Q

Lice

A

Pediculus humanus capitis (head louse),
Pediculus humanus corporis (body louse, clothes louse), and
Pthirus pubis (“crab” louse, pubic louse)

Three stages: eggs, nymphs and adult
Transmission by direct contact

47
Q

Name examples of ectoparasites

A
  • Sarcoptes scabei
  • Pediculus humanus capitis (head louse),
  • Pediculus humanus corporis (body louse, clothes louse), and
  • Pthirus pubis (“crab” louse, pubic louse)
48
Q

What are the subtypes of leishmaniasis?

A
  • mucosocutaneous
  • visceral
  • cutaneous
  • diffuse cuteaneous
49
Q

Visceral Leischmaniasis

A
  • also called Kala azar - black fever
  • most severe form, fatal if left untreated.
  • Characterised by irregular fever, weight loss, swelling of liver and spleen, anaemia
  • hepato and splenomegaly
  • thrombocytopenia, anemia, leukopenia (immunosuppression, low CD4+, low CD8+)
  • low BMI

RFs for development of clinical disease include:
• Malnutrition
• immune suppressive drugs
• HIV co-infections

VL case definition: “a person who presents with fever of more than two weeks and enlarged spleen
(splenomegaly) and/or enlarged lymph node (lymphadenopathy) or either of weight loss, anaemia or
leucopenia while living in a known VL endemic area or having travelled to an endemic area”.

50
Q

Cutaneous leishmaniasis

A
  • skin lesions on exposed body parts, often self-healing.
  • Can create serious disability and scars.
  • Immunity to reinfection
  • Large, irregular ulcer; surrounded by papular and crusted
    lesions which all contain parasites
51
Q

Diffuse cutaneous leishmaniasis

A
  • disseminated lesions,
  • resembles leprosy (social problems, ostracised from society, women can’t get married because of it) , difficult to treat, no spontaneous healing, frequent relapses
  • Multiple, nodular non-ulcerating lesions
52
Q

Mucocutaneous leishmaniasis

A
  • disfiguring, destroys mucous membranes
  • no spontaneous healing
  • relapses
53
Q

Kala Azar

A
  • another name for visceral leishmaniasis

- means black fever

54
Q

Diagnosis of visceral leishmaniasis

A

VL case definition: “a person who presents with fever of more than two weeks and enlarged spleen
(splenomegaly) and/or enlarged lymph node (lymphadenopathy) or either of weight loss, anaemia or
leucopenia while living in a known VL endemic area or having travelled to an endemic area”.

Laboratory investigations
a) Parasite detection: definitive diagnosis of VL is made by visualization of the amastigote form of the parasite by
microscopic examination of aspirates from lymph nodes, bone marrow or spleen aspiration
b) Direct agglutination test (DAT) and rK39 chromatographic test

55
Q

PKDL

A

Post - Kala-azar dermal Leishmaniasis

• frequent in Sudan and India
• in ~55% of patients in Sudan,
    in 5-10% in India
• Occurs during or after treatment,
after sub-clinical infection
• Lesions start on face, usually around
mouth
• Lesions can become nodular
• PKDL can spread to the trunk and
limbs.
56
Q

Take home messages

A

Parasitic infections - Take home messages:

Parasites infect much of the world’s population. Protozoal and heminthic infections are commonly referred to as “parasitic” infections and many of them belong to the group of neglected tropical diseases (NTDs).
A parasite is an organism that lives in (or on) its host, is dependent on the host for nutrition, often causing damage/disease. Infection vs disease: Infection is invasion by and growth of pathogenic microorganisms within the body. Disease is a disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors, illness, ailment.  Protozoa are single celled eukaryotic organisms, their genome is contained within a nucleus and their cytoplasm contains complex organelles. The pathogenesis (mechanisms by which they cause disease) is varied and many are carried and transmitted by insect vectors (example: sand flies transmit Leishmania parasites; malaria is caused by mosquitos transmitting Plasmodium spp .
Vector-derived products can influence the host response
Protozoa can be divided into: Amoebae (pathogenic: Entamoebae histolytica; non pathogenic: Entamoeba dispar); Coccidia (Plasmodium spp., Toxoplasma, Cryptosporidium); Flagellates (Giarida; Trypanosoma, Leishmania, Trichomonas), Ciliates (Balantidium)
Helminths are complex multicellular organisms (metazoa), can be free living, transmitted by vectors and their life cycle often involves an intermediate host. Humans are the definitive host. Adult worms lay eggs or produce microfilariae but cannot themselves multiply in man – therefore they are frequently a cause of morbidity rather than mortality. Helminths (worms) can be divided into: Round worms (Nematodes), Flat worms (Cestodes) and Flukes (Trematodes).

57
Q

Treatment of Leishmaniasis

A

sodium stibogluconate (SSG)

58
Q

How is leishmaniasis spread?

A

Sandflies

59
Q

Forms of Leishmania

A
  •  promastigote
  •  amastigote

Promastigotes
• Form of Leishmania within sand fly vector
•  move in the direction of their flagellum
•  Can be cultured

Amastigotes:
•Form of Leishmania within human or other vertebrate host’s cells (have resorbed their flagellum).
•They are no longer motile.

Year 2 - MCD - Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions