HSC 2
Infective diseases
Davies: Chapter 2
Terminology
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Pyrexia ↑ fever
Tachycardia ↑ heart
rate
Lesion wound,
structural tissue
damage
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Focus area of disease
e.g. Ghon focus
Complications
additional pathology
following initial
disease
Infectious fever
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Infectious disorders
transmits easily
Epidemic: periodical
outbreaks affecting
large numbers
Endemic: present in
community, but small
numbers
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Incubation period time from acquiring
infection till 1st
symptoms appear
Common feature:
multiple inflammatory
skin lesions (rash)
Infectious skin rashes
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Macules: spots
Papules - “pimples”
spots raised above
skin
Vesicles small blisters;
clear fluid
Pustules – pus
containing blisters
Petechial rash
purplish rash
 Causes: bacterial or
viral
 Active or passive
immunization as
preventative
measures
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Macules(spots)
Papules(pimples)
Vesicles small(blisters)
Pustules(pus pimples)
Petechial rash(purple)
Cot death (SIDS)
Virus infection suspected
 Still of unknown aetiology
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Measles
Virus infection
 Incubation period: 10-14days
 Rash ± 4 days
 Clinical features: conjunctivitis; Koplik’s
spots /white spots in the mouth
 Complications: bronchopneumonia; otitis
media
 Active immunization
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German measles (Rubella)
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Viral
Red rash
Widespread glandular
enlargement
Incubation period 14 –
21 days
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Complication 1st
trimester of
pregnancy e.g.
deafness etc
Blood test; establish
rubella antibodies
Females: active
immunization
Whooping cough (Pertussis)
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Bacterial: Bordetella
pertussis
Incubation period: 814 days
inflammation URT +
dry cough,
accompanied with
whooping cough
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Complications:
Bronchopneumonia
Atelectasis of
segments of lung
Convulsions “fits’
Treatment: antibiotics
Mumps (ependemic parotitis)
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Viral
Acute inflammatory of
parotid salivary glands
Incubation period: 1421 days
No specific treatment
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After puberty,
complications
Orchitis inflamm of
testes → sterility
Oophoritis inflamm of
ovaries
Chickenpox (Varicella)
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Rash:
Vesicular or pustular
Incubation period: 1421 days
Complication:
pneumonia
Smallpox (Variola)
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Classical smallpox
(variola major): can
be fatal
Alastrim (variola
minor) – less fatal
Incubation: 12 days
Various rash stages:
macular→ papular →
vesicular →pustular
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Features:
Pyrexia
Toxaemia -blood
poisoning by toxins
from a local bacterial
infection.
Myocarditis
Virus pneumonia
Treatment: penicillin
Active immunization
Day 3
Day 8
Day 20
Child with Smallpox - Bangladesh
Diphtheria
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Corynebacterium
diphtheria
causes a thick covering in
the back of the throat.
Infects throat, nose,
larynx, rarely skin
Incubation period: 2-8
days
Can cause distant tissue
damage; poisonous
exotoxin via blood
Treatment: penicillin &
diptheria antitoxin
Active immunization
“Schick test: absence or
presence of immunity
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Complications:
Myocarditis
Palatal paralysis - of the
soft palate
Ciliary paralysis: paralysis
of muscles that supply the
eyebrows
Respiratory paralysis
Peripheral neuritis: nerve
damage to limbs
Diphtheria
Skin lesions on the leg / neck
Acute Anterior poliomyelitis
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Cause: poliovirus
Non-paralytic &
Paralytic stage
Mainly childhood ,
infantile paralysis
Affects motor nerve
cells in spinal cord &
brain
Degree of damage
varies
Polio vaccine
Scarlet fever / Scarletina
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Variety of
streptococcus
Secretes exotoxin
Produces scarlet rash.
Incubation per: 1-8d
Complications: acute
nephritis & rheumatic
fever
Typhoid fever
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Severe infections
small bowel due to
salmonella ; stupor (a
state of nearunconsciousness),
coma
Spread by water or
food
Main features:
septicemia; stepladder fever; scanty
rash (rose-spots);
diarrhoea; stuporous
state
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Diagnostic tests:
Blood culture & Widal
test
Incubation per: 7-14d
Complications:
enteritis→ ulcer
heamorrhage; bowel
perforation;
cholecystitis
Active immunization:
TABC vaccine
Typhoid A, B & cholera
Childhood immunization
Vaccine
Diptheria / Tetanus /
Pertussis & oral polio
Measles / mumps /
rubella
Age
3 months
4.5 – 5months
8.5 – 11months
12-18 months
Diptheria / tetanus & oral 4-5 years
polio
Meningococcal Meningitis
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Bacterial cause:
Spreads to
bloodstream from
nasopharynx
Causes septicaemia
Early stage called:
spotted fever
Neck rigidity
Stained LP:
Complications:
paralysis;
bronchopneumonia;
hydrocephalus
Pyogenic infections /
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Common causes:
staphylococcus &
streptococcus
pathogens
Staphylococcus:
Localized abscess
Furuncle (boil)
abscess in hair follicle
or sweat gland
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Carbuncle: several
abscesses in localized
area
Bone: staphylococcal
osteomyelitis
Lung: staphylococcal
pneumonia
Staphylococcal pneumonia
Brodie’s abscess
Osteomyelitis
Streptococcal infections
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Produces diffuse
spreading lesions
Lymph: lymphangitis /
lymphadenitis
Blood: streptococcal
septicaemia
Skin: cellulitis:
inflamm. Of
connective tissue
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Pharynx: streptococcal
tonsillitis
Ear: otitis media
Bone: streptococcal
osteomyelitis
Heart: subacute
bacterial endocarditis
(SBE)
Streptococcal infections
Tuberculosis
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Aetiology
Inhalation of air: Cough
main spread
Ingestion of contaminated
food
Basic lesions: nodules
Diagnosis: x-rays; Sputum
test; Biopsy; bronchoscopy
Symptoms: anorexia,
fever, chronic cough
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Caused tubercle bacillii
Primary TB
TB bacteria transported to
lymph nodes; if multiply;
Primary TB develops
Post-primary TB
Reactivation
Upper lobes & Cavities
Complication in AIDS Pt.
TB
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D.O.T.S.(Directly
Observed Treatment
Short course)
Volunteers
Monitors TB patients
treatment &
medication
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CXR
Different patterns
determine type of TB
Primary
Secondary
Miliary TB
Chronic
Old TB Scarring
Follow-up: determine
success of treatment
Sexually transmitted Disease (STD)
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Syphilis
Congenital
Acquired: spirochate
Primary: chancre (cyst)
Secondary: Bloodspread:
General infections: Skin
rashes, sore throat
Tertiary stage: confined to
particular organ eg.
neurosyphilis (brain)
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Gonorrhoea
Males: acute inflammation
of urethra → prostatitis
Females: urethritis or
cervicitis → salpingitis
Complications: male urethral
stricture
Infants: opthalmia neonatorum
Syphilis
Scabies
↓
Gonorrhoea
↓
Acquired Immune Deficiency Syndrome
(AIDS)
Infection by HIV virus
 Attacks body’s immune system →
immunodeficiency
 Long incubation period = 10yrs
 Due to immunodeficiency = infections eg.
Pneumonias & other unusual neoplasms
like Kaposi’s sarcoma and cerebral
lymphoma
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Transmission = sexually, contaminated
blood (donors / drug users), transmission
from mother to child
 Palliative treatment / fatal
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Tropical diseases – Diseases that show
their greatest incidence in warm climates
Malaria: A parasitic disease transmitted
through mosquito bites.
 Most common tropical disease
 Symptoms:
 Fever
 Shaking
 Chills
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Cholera – bacterial infection of the small
intestine due to pathogens, causing
inflammatory changes in the large bowel
 Sign & symptoms:
 Diarrhoea
 Vomiting
 Dehydration
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