Microbiology - Healthy & Unhealthy Communities Flashcards Preview

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Flashcards in Microbiology - Healthy & Unhealthy Communities Deck (77)
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1
Q

Key factors determining the travel-related risk

A

Mode of transportation
Destination (local infection epidemiology)
Season of travel
Duration of travel
Standards of accom, food hygiene and sanitation
Behaviour of the traveller/ purpose of travel
Underlying health of traveller

2
Q

Why is the epidemiology of infectious diseases of importance to travellers

A

Outbreaks of known or newly emerging infectious diseases are often predictable – decision on need for certain vaccine or antimalarial prophylaxis

3
Q

Risky behaviour of travellers

A

Going outdoors in the evenings in an malaria-endemic area without taking precautions
Swimming in Schistosoma infested lakes
Exposure to insects, rodents, bats and other animals
Contaminated food/ water is a major risk
Unprotected sexual intercourse

4
Q

Epidemiology of gastroenteritis

A

Worldwide in endemic areas, 1.5 million children die yearly due to infectious gastroenteritis
Viral gastroenteritis accounts for ~68% of all gastroenteritis episodes in travellers

5
Q

Causative agents of gastroenteritis

A

Rotavirus
Norovirus
Astrovirus

6
Q

Causes of bacterial gastroenteritis

A
Campylobacter jejuni 
(Enterotoxigenic) E. coli 
Salmonella 
Shigella 
Vibrio cholerae
7
Q

GE presentation

A
Anorexia 
Nausea 
Vomiting 
Diarrhoea 
Abdominal discomfort
8
Q

GE dx

A

Clinical evaluation

Stool testing

9
Q

GE treatment

A

Oral or IV rehydration

Abx in select bacterial cases and if bacteraemia

10
Q

Where is infectious hepatitis prevalent

A

In areas of developing countries with poor sanitation, crowding and lack of access to clean water

11
Q

Enterically (food and waterborne) transmitted viral pathogens

A

Hep E

Hep A

12
Q

Transmission of Hep E

A

Faeces (drinking contaminated water or eating contaminated food)

13
Q

Outbreaks of Hep E

A

Seasonal, often associated with monsoon period

14
Q

Incubation of Hep E

A

3-7 weeks

15
Q

Attack rate of Hep E

A

1 in 2

16
Q

Mortality of Hep E

A

<1% but 15-25% in antenatal women

17
Q

Severity of Hep E

A

Increases with age

18
Q

Vaccine for Hep E

A

Developed – in use in China, Nepal

19
Q

Prevention and control measures for Travellers to Hep E endemic regions

A

Avoid drinking water (and beverages with ice) of unknown purity
Uncooked shellfish
Uncooked fruit/ vegetables not peeled or prepared by traveller

20
Q

Hep A infection characteristics

A

Acute, self-limiting infection of the liver
Infection may be asymptomatic in children
Adults symptomatic
Rarely, fulminant hepatitis can ensue

21
Q

How many serotypes are there of Hep A

A

Only one

22
Q

How many genotypes of Hep A are there

A

Multiple genotypes have been identified incl 4 human genotypes

23
Q

What type of virus is Hep A

A

A single-stranded, +ve sense, linear RNA virus of 7.5 kb in length

24
Q

General Hep A prevention

A

Good hygiene

25
Q

Hep A - pre-expsoure

A

Active immunisation vaccine (killed whole virus)
Travellers to intermediate and high-risk areas
Individuals at risk due to sexual behaviour, parenatal drug abuse

26
Q

Hep A - post-exposure

A
Vaccine (within 7 days)
Immunoglobulin HNIG (within 14 days of onset of disease in primary case)
27
Q

Hep A vaccine

A

Prepared from formaldehyde inactivated Hep A virus grown in human diploid cells
2 types of vaccine – single and combined

28
Q

Single component Hep A vaccine

A

Havrix
Epaxalm Avaxim
Vaqta Paediatric

29
Q

Combined Hep A vaccine

A

Hep B vaccine (Twinrix) or thyroid vaccine (Hepatyrix)

30
Q

Arthropod

A

Mosquitoes and ticks

31
Q

Mosquito-borne parasitic infection

A

Malaria

32
Q

Mosquito associated viral infections

A
Dengue types 1, 2, 3, 4
Japanese encephalitis 
Murray valley encephalitis 
St Louis encephalitis 
West Nile virus 
Zika virus
Yellow fever 
Chikungunya virus
33
Q

Transmission of Dengue fever

A

Transmitted to people by bite of Aedes mosquito that is infected w/ dengue virus

34
Q

Symptoms of Dengue fever

A
High fever
Severe headache 
Severe pain behind eyes 
Joint pain 
Muscle and bone pain 
Rash 
Mild bleeding (e.g. nose or gums bleed, easy bruising)
35
Q

Dengue haemorrhage fever

A

Characterized by a fever that lasts from 2-7 days, w/ general signs and symptoms consistent w/ dengue fever
When the fever declines, symptoms incl persistent vomiting, severe abdominal pain and dyspnoea may develop

36
Q

When does haemorrhage occur in dengue haemorrhage fever

A

Haemorrhage follows leading to failure of the circulatory system and shock, leading to death if circulatory failure is not corrected

37
Q

Tick-borne infections

A
Tick-borne encephalitis (Central European, Far Eastern, Siberian)
Kyasanur Forest disease (Alkhumra)
Louping ill
Omsk haemorrhagic fever 
Powosan 
Crimean-Congo haemorrhagic fever
38
Q

What does Crimean-congo haemorrhagic fever causes

A

Causes severe viral haemorrhagic fever outbreaks

39
Q

Case fatality of CCHF

A

10-40%

40
Q

Incubation period of CCHF

A

1 - 3 days

41
Q

Symptoms of CCHF

A

Fever, myalgia, neck stiffness, backache, headache, photophobia
Nausea, vomiting, diarrhoea, abdominal pain, mood swings, confusion

42
Q

Complications of CCHF

A

Bleeding into the skin, mucosa, internal organs

Liver failure, kidney failure

43
Q

VHFs

A

Viral haemorrhagic fevers (VHFs) refer to group of epidemic prone diseases that are caused by several distinct families of viruses

44
Q

Characteristic of VHFs

A

The overall vascular system is damaged and the body’s ability to regulate itself is weakened
Symptoms can often be accompanied with life-threatening bleeding

45
Q

VHFs found in Africa

A
Marburg and Ebola haemorrhagic fevers
Crimean-Congo haemorrhagic fever (CCHF)
Rift Valley fever (RVF)
Lassa fever
Yellow fever
46
Q

TB

A

A severe infectious disease caused by various strains of mycobacteria, most commonly Mycobacterium tuberculosis

47
Q

Infection of TB

A

People are infected w. TB by inhaling airborne droplets produced by infectious TB carriers
Latent TB infection (LTBI) carriers are asymptomatic and not infectious

48
Q

BCG vaccine and TB

A

Provides partial protection

49
Q

Treatment for TB

A

Standard treatment of TB consists of a six-month regimen of 4 first-line drugs (isoniazid, rifampicin, ethambutol and pyrazinamide)

50
Q

Case fatality of MERS-CoV

A

35.5.%

51
Q

Transmission of MERS-CoV

A

Human-to-human

52
Q

Symptoms of MERS-CoV

A

Symptoms icl fever, cough and SOB
Pneumonia is common, but not always present
GI symptoms incl diarrhoea, have also been reported

53
Q

Rabies

A

Vaccine-preventable viral disease which occurs in more than 150 countries

54
Q

Main source of human rabies death

A

Dogs, contributing up to 99% of all rabies transmissions to humans, however any mammal can transmit rabies

55
Q

Mx of suspected rabies

A

Immediate, thorough wound washing with soap and water after contact with a suspect rabid animal is crucial followed by post-exposure prophylaxis (rabies vaccine and RIG)

56
Q

Monkey pox

A

Rare viral zoonotic disease that occurs primarily in remote parts of central and west Africa, near tropical rainforests

57
Q

Monkeypox trasmission

A

Mostly transmitted from various wild animals such as rodents and primates, but has limited secondary spread through human-to-human transmission

58
Q

Treatment of smallpox

A

No spp treatment or vaccine available although prior smallpox vaccination was highly effective in preventing monkeypox as well

59
Q

Malaria

A

Life-threatening illness caused by infection of red blood cells by Plasmodium parasites.
Notfiable disease

60
Q

Who should immediate admission arranged for of those with suspected malaria

A

People with suspected severe or complicated malaria
People with suspected falciparum malaria
Pregnant women
Children
People who are older than 65 years of age.

61
Q

Human malaria parasites

A
P. falciparum (malignant tertian)
P. vivax (benign tertian) 
P. malariae 
P. ovale 
P. knowlesi
62
Q

Malaria epidemiology

A

Restricted to areas mosquitoes can breed: tropics between 60 degrees N and 40 degrees S. 90% of cases occur in Africa, 7% in South-East Asia and 2% in Eastern Mediterranean region

63
Q

Presentation of malaria

A

Fever (most common), general malaise, headache, myalgia & arthralgia, confusion and vomiting or diarrhoea

64
Q

Splenomegalogy and malaria

A

Experienced by many older children and adults

Occurs as erythrocytes burst due to osmotic fragility caused by parasitic infection

65
Q

P. vivax - malaria

A

Develops into chronic febrile illness with severe mortality, causes malaria with pronounced anaemia and respiratory illness

66
Q

P. ovale and P. malariae

A

Usually self-limiting but can recur as they often form hypnozoites that can represent with anaemia even years after original infection (decades)

67
Q

Most dangerous Plasmodium infection

A

P. falciparum malaria is frequently fatal during first 2 weeks because of a variety of complications.

68
Q

Ix for malaria

A

Travel hx paramount
Examine the patient looking for signs of severe malaria such as impaired consciousness, confusion, hypotension, respiratory distress or jaundice

69
Q

Dx of malaria

A

Only possible with microscopy of thick and thin blood films or an antigen detection test
If the first blood films are -ve, further blood testing must be arranged 12 to 24 hours later and again after a further 24 hours to rule out infection.

70
Q

Hypnozoites

A

Dormant parasites which persist in the liver after treatment

71
Q

Drug of choice for malaria

A

IV artesunate, but this can cause haemolysis and follow-up blood tests are required.

72
Q

2nd drug of choice for severe/ complicated malaria

A

IV quinine

Requires cardiac monitoring and regular BMs as there are risks of arrhythmias and hypoglycaemia

73
Q

ACT

A

Artemisinin combination therapy
May be used to treat uncomplicated malaria and is the preferred treatment for mixed infection as it can help avoid development of drug resistance

74
Q

Chlorquine for malaria

A

May be used to treat uncomplicated P. malariae, P. ovale and P. knowlesi and most cases of P. vivax malaria but use depends upon patterns of resistance and tolerance.

75
Q

Primaquine for malaria

A

Used to prevent relapse of benign malrias as it eradicates hypnozoites (P Vivax and P. Ovale)

76
Q

Poor prognostic factors of malaria

A
High levels of parasitaemia
Peripheral P. falciparum blood schizonts
Pigment deposits in leucocytes
Metabolic acidosis
Older age
Coma 
Renal impairment (organ dysfunction)
77
Q

Drugs used for malaria

A
Artesunate 
Quinine 
ACT
Chloroquine
Primaquine

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