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Year 2 - MCD Microbiology > Parasitic Infections > Flashcards

Parasitic Infections Flashcards

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Biology 101 flashcards
1
Q

Define Infection vs. Disease•

A

 Infection:
invasion by and growth of pathogenic microorganisms

 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 unfavourable environmental factors; illness; sickness; ailment.

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2
Q

Define Parasite

A

Organism living in/on a host
AND
is dependent on the host’s function – causing damage.

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3
Q

Two subtypes of parasites?

A

 Endoparasites:

• Protozoa
– amoeba, coccidia, ciliate, flagellates

• Metazoa (helminths)
– roundworms, flatworms, flukes

 Ectoparasites

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4
Q

Explain Protozoa and facts about it

A

 Protozoa – single-celled organisms:

  • Eukaryotic organisms – genome is within a nucleus, complex organelles
  • Causes of pathogenesis varies
  • Some have insect vectors
  • NO eosinophilia
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5
Q

Explain Metazoa and facts about it

A

 Metazoa – multi-cellular organisms:

  • Free living
  • Have intermediate hosts and vectors
  • Some just inhabit the gut (geo-helminths) whilst other invade tissues
  • Eosinophilia if they invade the blood
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6
Q

Endoparasites - protozoa examples?

A

” A Cell Causing Fever”

A - Amoeba
C - Coccidiae
C - Ciliates
F - Flagellates

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7
Q

Explain the “A” of Protozoa - its different forms and how it causes infections

A

Amoeba

Genus: Entamoeba

• Entamoeba histolytica
- infects 10% of population
• Entamoeba dispar
- NORMAL COMMENSAL of the GI tract

Infection occurs by:
• INGESTION of MATURE CYSTS in food or water OR on hands

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8
Q

Epidemiology of “A” of Protozoa

A

Amoeba

3rd most common cause of death
• after schistosomiasis & malaria

90% of infections are ASYMPTOMATIC

Incubation period:
• can be short as 7 days
BUT
• upto 4 months as tissue invasion occurs during first 4 months

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9
Q

Explain “A” of Protozoa - life cycle, symptoms, diagonsis & treatment

A

Life cycle:
• HUMANS ONLY reservoir
• Cysts enter S.I and release parasites (trophozoites) = invade L.I epithelial cells = cause ULCERS
• Infection spreads via. venous system

Diagnosis:
• wet mount - microscopy of cysts

Treatment:
• Nitroimidazole derivatives, parmomycine or diloxanide furoate

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10
Q

Explain the first “C” of Protozoa and state what its organisms and associated diseases are briefly

A

Coccidia

Organisms & Associated Disease:
 Plasmodium species
– malaria

 Toxoplasma
– toxoplasmosis
– mild disease in immunocompromised – major for pregnancy!

 Cryptosporidium
– diarrhoea.

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11
Q 
Explain the FIRST organism of Coccidia and the related information:
Facts
Symptoms
Treatments
Diagnosis
A

PLASMODIUM - malaria

Facts:
• 2 hosts include humans and female anopheles’ mosquito.
• 2 stages in humans – liver and blood stages

Symptoms:
– fever, headache, chills, emesis, myalgia

Complications:
– severe anaemia (due to RBC destruction)
– cerebral malaria (brain oedema = coma)

Treatments
– uncomplicated malaria = Chloroquine
– severe malaria = ACT (combination)

Diagnosis:
• blood film
• antigen detection tests

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12
Q

Explain the SECOND organism of Coccidia and the related information

A

TOXOPLASMA - toxoplasmosis

Toxoplasmosis gondii

Hosts:
• infected food (warm-blooded animals with cysts or cat faeces contamination)

Transmission:
 • blood transfusion
 • faeco-oral
 • organ transplantation
 • trans-placentally to foetus

Normally asymptomatic:
• problematic in pregnancy/immunocompromising

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13
Q

Explain the THIRD organism of Coccidia and the related information:
Symptoms
Diagnosis
Treatment

A

CRYPTOSPORIDIUM - diarrhoea

Symptoms:
• diarrhoea, fever, nausea, emesis
• Very common in HIV patients

Diagnosis:
– stool examination

Treatment:
– fluid rehydration

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14
Q 
Explain the second "C" of Protozoa and state what:
Organisms
Hosts
Symptoms
Diagnosis
A

CILIATES

Organisms:
– Balantidum coli –> balantidiasis

Reservoir hosts:
– pigs, rodents, primates (infects people worldwide)
• transmission via. faeco-oral route

Symptoms:
 Most asymptomatic
Immunocompromised people – persistent diarrhoea, dysentery, abdominal pain, weight loss, nausea, emesis; all leading to perforation of the colon

Diagnosis:
• stool examination

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15
Q

Explain the “F” of Protozoa and state what Organisms are generally associated with it

A

FLAGELLETES

Organisms:
 Giardia lamblia –> Giardiasis
– symptoms: diarrhoea

 Trichomonas

 Leishmania
– sand fly vector
– 4 main types of Leishmania

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16
Q

Explain the organism Trichomonas of Flagellates

A

Transmitted sexually

Symptoms:
• Females
– 10-50% asymptomatic
– vaginal discharge, vulval itching, dysuria

• Males
– 15-50% asymptomatic
– discharge and/or dysuria

 May enhance HIV risk and is very bad for pregnant women.

Diagnosis and treatment:
– microscopy and metronidazole.

17
Q

What makes up Endoparasites - Metazoa?

A

Worms!
• roundworms
• flatworms
• flukes

18
Q

What are some facts about the life cycles of metazoa/helmiths

A

Cycles may involve insect vectors and intermediate hosts.
 for most, humans are the DEFINITIVE host – a few are zoonoses (acquired from animals)

o Adult worms can NOT multiply in man
– the number of adults is related to the infection

o A large burden is found in school-aged children which has a massive effect on their development

19
Q

Examples of the diseases caused by Metazoa?

A 
Roundworms/Nematodes
 • Ascaris
 • Hookworm
 • Filaria
 • Strongyloides

Flatworms/Cestodes
• Taenia (tapeworms)

Flukes/Trematodes
• Schistosoma

20
Q 
Explain the "A" of Roundworms/Nematodes stating:
Life Cycle
Symptoms
Diagnosis
Treatment
A

ASCHARIASIS (most common infection worldwide)

Life cycle:
 Live in the S.I and eggs are passed with faeces
 After infective eggs are swallowed, larvae hatch and invade the intestinal mucosa
 They are carried via the portal and then systemic circulation to the lungs
 The larvae mature in the lungs, penetrates the alveolar walls, ascends and is then swallowed.
 When they reach the S.I , they develop into adults (live for 1-2 years)

Symptoms:
• often asymptomatic BUT can cause abdominal pain or intestinal obstruction

 Adults feed on SI contents –> malnourishment
 Penetration of lungs can cause Loeffler’s pneumonia – pools of blood clog the lungs

Diagnosis:
– stool examination

Treatment:
– albendazole or mebendazole

21
Q 
Explain the "H" of Roundworms/Nematodes stating:
Life Cycle
Symptoms
Diagnosis
Treatment
A

HOOKWORM
• cause iron-deficient anaemia AS it causes localised bleeding

Life cycle:
 Larvae are carried through the circulatory system to the heart and then lungs.
 Penetrate the alveoli and ascend to be swallowed and reach the SI to mature.
 In the SI, they attach to the lumen and cause localised bleeding

Symptoms:
 – iron deficient anaemia
 – cardiac complications
 – local skin manifestations
 – respiratory symptoms

Diagnosis:
– stool examination

Treatment:
– albendazole or mebendazole

22
Q 
Explain the "F" of Roundworms/Nematodes stating:
Main types
Symptoms
Diagnosis
Treatment
A

FILARIA, Lymphatic filariasis

2 main types:

(1) Brugia malayi
(2) Wucheria bancrofti

Symptoms:
– cause ELEPHANTIASIS when they block the lymphatic systems
– Microfilariae are found in peripheral blood.
 during the day, they are present in deep veins and at night they migrate to the peripheral circulation

Diagnosis:
– blood smear OR antigen detection with an immunochromatic test (CARD) OR ELISA

23
Q

Explain the “L” of Roundworms/Nematodes stating:
Life Cycle
Symptoms

A

LOIASIS - Loa Loa

o These can get into the eye
o Confined to Africa
o Adults can live for 4-12 years

Life cycle:
 Females migrate through the SC tissues and may cross the front of the eye
 Microfilariae circulate in the blood from where it can be picked up by the Chrysops
 In the gut of the fly, the larvae mature into the infective third stage larvae
 These larvae infect the next host when chrysops takes a blood meal and they mature into adults.

24
Q 
Explain the example of Flatworms/Cestodes, giving:
Hosts
Symptoms
Diagnosis
Treatment
A

Tapeworm: TAENIA

HUMANS are the ONLY DEFINITIVE HOSTS for:
 Taenia solium, Taenia asiatica – PIG.
 Taenia saginata – BEEF

Symptoms
– most people are asymptomatic

 T. saginata often experience more symptoms – abdominal pain, loss of appetite, weight loss, upset stomach.
 T. solium causes cysticercosis – most common cause of acquired EPILEPSY worldwide

Diagnosis:
– tapeworm segments in stool OR identification of eggs in stool

Treatment:
– Praziquantel

25
Q 
Explain the example of Flukes/Trematodes, giving the:
 Main Types
Life Cycle
Symptoms
Diagnosis
Treatment
A

SCHISTOSOMIASIS

3 main types:
 Schistosoma mansoni
(Eggs to SI)

 Schistosoma haematobium
(Eggs to bladder and ureter)

 Schistosoma japonicum
(Eggs to SI)

Life cycle:
 Eggs eliminated in water via faeces or urine
 These hatch and release miricidia, which penetrates the snail. The snails release cercariae that penetrate the skin.
 They then migrate to different tissues and transform into adults and females which reside in venules
 Eggs move progressively towards the lumen of the SI (mansoni and japnicum) or the bladder and ureters (haematobium)

Symptoms:
 Days – rash/itchy skin – most people are asymptomatic early on.
 Months – fever, chills, cough, myalgia

• Repeated infection in children can cause anaemia, malnutrition and learning difficulties

Diagnosis:
– stool or urine examination.

Treatment:
– praziquantel

26
Q

Example of Ectoparasites?

A

Scabies
• Sarcoptes Scabei

Lice

27
Q

What are symptoms and treatment for Scabies?

A

Symptoms:
• rash
• burrows presence

Treatment:
• Scabicides

28
Q

What are the different types of Lice and its life cycle?

A

Types of lice:
 Pediculus humanis corporis
– body louse

 Pediculus humanis capitis
– head louse

 Pthirus pubis
– crab louse of pubic area

Life cycle:
o Exist in 3 stages – eggs, nymphs, adults.
o Transmission is by direct contact

29
Q

What are different forms of Leishmania Protozoan?

A

Leishmania - example of a Flagellates (Protazoa)

Promastigote
• transmitted by sand fly

Amastigote
• IC in host

30
Q

What are the major forms on leishamaniases disease?

A 
Visceral leishmaniasis (kala azar) - most severe:
   Most = subclinical, but when symptomatic = very dangerous
  Fever, hepatosplenomegaly, anaemia, fatal if left uncured

Cutaneous leishmaniasis:
 Skin lesions, often self-healing – but can create serious disability and scars
• May be localised, diffuse or mucocutaneous

Localised Cutaneous
– “crust” development is representative of healing
 Recovery from localised form –> resistance: basis for a vaccine

Diffuse Cutaneous
 resembles leprosy and difficult to treat
 causes nodular non-ulcerating lesions

Mucocutaneous
 disfiguring - as destroys mucous membranes

31
Q

What is meant by Vector?

A

An organism that transmits a disease or parasite from one organism to another

32
Q

Examples of vestors?

A

 Snail
– transmits schistosomiasis (Fluke, Metazoa, endoparasite)

 Female anopheles’ mosquito
– transmits malaria (Coccidia, protozoa, endoparasite)

 Chrysops
– transmits Loiasis (Roundworm, Metazoa, endoparasite).

Year 2 - MCD Microbiology (6 decks)

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