This document provides information on fever (pyrexia), including: 1. Thermoregulation and how the body maintains a normal temperature of 37°C through the hypothalamus despite environmental variations. 2. Features of a normal body temperature and what constitutes a fever. Fever enhances the immune system and inhibits some microbes. 3. Patterns of fever onset, main phases, and end. Fever's diagnostic features and the importance of taking a thorough medical history are also outlined.

1. Approach to FEVER
Dr.Bilal Natiq Nuaman
C.A.B.M. ,F.I.B.M.S. ,D.I.M. ,M.B.Ch.B.
2016-2017

2. Thermoregulation
• Because Temperature affects how the enzymes work in your
body , People should maintain a normal body temperature of
about 37°C despite wide variations in both their metabolic
activity and the temperature of their environment.
Almost all enzymes have an "optimal" temperature. For
example, most human derived enzymes will function best at
around 37 ° C .If it gets too hot or cold the enzymes might
denature and lose the shape of their active site, which means
the substrate may no longer fit and this decreases the rate of
the chemical reactions.
•

4. •
HOMEOSTASIS
The body keeps its core temperature constant at about 37 C by
physiological adjustments controlled by the hypothalamus
(Thermostat Center) where there are neurons sensitive to
changes in skin and blood temperatures. The temperature-
regulating centers are found in the Preoptic Area (the anterior
portion of the hypothalamus).

5. Normal Features of Body
Temperature
1-the mean oral temperature is 36.8° ±
0.4°C
2-The normal diurnal variation is typically
0.5°C
(6 A.M. readings < 6 P.M. readings by 0.5
°C)

6. Fever is an elevation of body temperature that
exceeds the normal daily variation and occurs
in conjunction with an increase in the
hypothalamic set point (e.g., from 37°C to
39°C).
FEVER:
an A.M. temperature of >37.2°C (>98.9°F) or
a
P.M. temperature of >37. 7°C (>99. 9°F)

7. • 1-It enhance immune function;
• 2-Inhibits growth of some microbial agents:
Benefits of fever
• Increases motility and activity of the white blood cells
(T cells and B cells ).
• Stimulates the interferon production .
• Increase phagocytic activity
• Many of the microbial agents that cause infection grow
best at normal body temperatures, and their growth is
inhibited by temperatures in the fever range

8. Diagnostic Features of Fever
➢ Relative bradycardia:(rising of HR <5 /min. for each 1˚C rise )
Causes : Typhoid,Brucellosis,Leptospirosis,and Factitious fever
➢ Relative tachycardia (rising of HR >15/min. for each 1˚C rise )
Causes :Myocarditis, rheumatic fever
➢ Reversed diurnal pattern :(AM Temp. >PM Temp.)
Causes: Typhoid , disseminated TB
➢ Failure to have fever
Cause: Elderly,CRF,Corticosteroid

9. components of fever

10. 1-Onset of fever : (warming – chill phase)
Sudden rise : pneumonia,malaria,meningitis (associated with oral
herpes simplex).
Gradual rise : typhoid fever (step-ladder) .

11. The pattern of rise of temperature (1) Abrupt rise (2) Step-ladder pattern

12. 2-Main (pattern-plateau phase)
❖ Continuous: fever does not fluctuate more than 1˚C during
❖ Remitent : daily fluctuations exceed 2˚C but at no time touches
It is associated with viral upper respiratory tract, legionella, and
❖ Intermittent : fever reaches normal level
✓ Quotidian : Paroxysms of fever occur daily(P.Falciparum)
✓ Tertian : Paroxysms of fever on alternate days
(P.Vivax,P.Ovale)
✓ Quartan :every 72 hrs (P.Malariae)
24hrs, but at no time touches the normal.e.g.pneumonia,
typhoid fever, urinary tract infection, brucellosis
the normal.
mycoplasma infections

14. 3-End of fever :
Crisis (sudden reduction ){associated with sweating}
e.g. pneumonia
Lysis ( gradual reduction)
e.g. Typhoid

18. THE HISTORY
Presenting complaint
How has the fever been documented? What is its severity and time course? Have
there been rigors or sweating?
Has there been a rash or skin changes? If yes, ask about its timing in relation to
the fever, the distribution and direction of any progression and associated symp
toms, e.g. pruritus, local lymphadenopathy.
Systematically ask about localizing symptoms, e.g. cough, pleuritic chest pain,
purulent sputum, vomiting, abdominal pain, jaundice, diarrhea, dysuria, urinary
frequency, headache, photophobia, neck stiffness, altered consciousness, joint
pain, muscle aches, throat or ear discomfort and nasal discharge.
Are there constitutional symptoms, including easy fatiguability, anorexia, weight
loss, falls, change in daily activities or behavior? Such symptoms may indicate
infection in the elderly or immunocompromised.

19. Past medical history
Have there been previous or recurrent infections, illnesses, surgical
operations or dental treatment?
Has there been contact or residence in a healthcare facility (including
longterm care facility)?
Ask about a history of immunosuppression, e.g. HIV infection,
chemotherapy, steroid therapy transplantation, diabetes mellitus.
Ask about indwelling catheters, e.g. urethral, intravenous (IV) or
implants, e.g. pacemakers, joint replacements.

20. Drug history
Find out about all prescribed and non prescribed medications, e.g.
herbal remedies taken and ask specially about immunosuppressants
(including oral steroids), antibiotics (penicillin) ,
anticonvulsants(phenytoin) .
Have any ‘recreational’ drugs been taken; if so, have they ever been
injected?
Note any history of adverse reactions, allergies or hypersensitivity to
any drugs, particularly antibiotics.

21. Family history
Has the patient had contact with anyone with a similar illness?
Are there clusters of similar symptoms or infections among family, friends or
workmates?
Social history
Find out about exposure to animals, birds or pets and if so, is the animal unwell?
Note the patient’s occupation and hobbies.
support& financial situation, Social class.surrounding, Geographic area of living,
fresh-water swimming. or animals (avian flu , toxoplasmosis, brucellosis, rabies….)
(tuberculosis, brucellosis and Q fever).

22. Travel history
Has there been recent (in the past year) travel abroad? If so, take a detailed
travel history including:
• travel destinations: dates, duration, mode of travel,stopovers
• environment abroad: accommodation, altitude,climate, activities
• lifestyle: including diet, e.g. raw or unpasteurized products, sexual contact ,
water sports, healthcare, piercings, tattoos
• medical history: including vaccination status, preexisting conditions,
antimalarial measures, particularly type, duration and compliance.

23. ‘Red flag’ features indicating serious infection
• Altered mental state
• Headache and/or stiff neck
• Petechial/purpuric skin rash
• Hypotension – systolic blood pressure <90 mmHg
• Tachycardia – heart rate >90 bpm –with narrowed pulse pressure and weak pulse
• Tachypnoea – respiratory rate >20 breaths/min
• Recent travel to or recent arrival from malaria or tuberculosis endemic area
• Recent use of immunosuppressant drugs
• Significant active comorbidities (cancer, HIV, organ transplantation)
• Temperature > 38°C
• Rigors (chills)

27. FEVER AND MUCUS MEMBRANE RASH
(ENANTHEM)
• Koplik's spots in measles
• Forchheimer spots in rubella

36. Thank you