Fever with:
Rigors
Rigors means contained infections where toxins don’t find an exit to
be drained, so all enter into blood in high quantity e.g acute
abscess,pneumonia, cholangitis, UTI with obstruction, pyelonephritis,
meningitis or infections in blood like acute endocarditis or acute
malaria. Chronic infection don't cause rigors unless very extensive
areas involved.
Fever with Weightloss
Fever with significant weight loss usually excludes uncomplicated
acute infections, malaria, typhoid or brucellosis.
Fever with Lymphadenopathy
Fever with lymphadenopathy suggests systemic viral infections ( HIV,
CMV, EBV etc) or Toxoplasma or Lymphoma/Leukaemia, Sarcoidosis
or disseminated TB etc. Usually acute bacterial infections or chronic
fungal infections can give localised lymphadenopathy but generalised
isn't a feature of acute bacterial infection or fungal
infections.Lymphadenopathy is also not seen in malaria or connective
tissue disorders( books mention SLE but its very rare to be a dominant
feature in SLE ).
Fever with Localising signs
Fever with localising signs usually means infection in the organ.
Localising feature are usually not seen in uncomplicated typhoid,
malaria or brucellosis. Complicated enteric in late second or third
week will give GIT s/s involving ileum.
Fever with Splenomegaly
Fever with early splenomegally in the first few days indicate infection
in blood or infection in RBCs like malaria, babesiosis or endocarditis.
Splenomegally in second week or later indicates any bacteremic or
disseminated infection.
Fever with Hepatomegaly
Fever with isolated tender hepatomegally without splenomegally
usually means infection is in liver, whereas mildly tender
hepatomegally with high ALP will mean chronic infections like TB,
fungal etc whereas high ALP with non tender hepatomegally with
fever favours non infective causes of fever.eg TB liver is mildly tender
where as sarcoidosis is non tender usually.
Fever withNeutrophilia
Fever with neutrophilia indicates acute bacterial infection . Gram
negative bacteremic , viral infections or chronic bacterial infections,
fungal infection usually cause leukopenia or normal WCC.
Fever with very high ESR usually means chronic infections or
autoimmune problems or haematological malignancy. Usually acute
infections don't cause very high ESR like 80s or above.
Afebrile Infections
Absence of fever in infection OR hypothermia in infection( rather than
Hyperthermia )is possible in following conditions:
We need fuel ( glucose , fats) to burn in tissues like muscles and liver
to produce heat. This process in initiated by inflammatory mediators
which stimulate Hypothalamus. From hypothalamus, then message
goes to heat generating organs. In addition hypothalamus also uses
autonomic system to cause cutaneous vasoconstriction to conserve
heat.
Any problem at any step may fail to generate or conserve heat despite
infection. So following conditions may not mount fever despite
infections;
Immunosuppressed patients ( steroids, immune disease,
immunosuppression drugs, end stage organ failure, dialysis,
Transplant etc are all immunosuppressed).
Hypothalamus diseaseAutonomic neuropathy Hypoglycaemia/
malnourished patients.Liver failureMuscle wasting conditions like
Myopathies.
Patients with end stage failure of metabolically active organs like
liver, kidneys, brain etc.
Drugs impairing any of the above heat generating or conserving
system.Very old and frail patients.Paediatric population
So any deterioration in these patients should raise suspicion of
infection despite absence of fever or raised inflammatory markers.
Rigors & Chills
These are not a spectrum of the same process. They are two different
symptoms. Essentially the disease which cause rigors are more serious
and alarming.
Rigors indicates the following facts ( which chills Does Not):
1. Blood culture is essential.
2. Bacteremia unless proven otherwise. Viruses are rare to cause and
a very few viruses cause rigors.
3. Patient need hospitalisation & IV antibiotics unless proven
otherwise.
4. It's contained infection where toxins are not finding any exit and
the only place they can go is into the blood.
5. Infection on top of obstructed duct like ureter ( pyelonephritis or
UTI with bladder outflow obstruction),bile duct ( cholangitis) etc . OR
contained infection like Abscess, Pneumonia, pyogenic Meningitis. OR
infection in the blood stream like Endocarditis, Bacteremia of any
source, malaria etc.
6. Fever has to be at least or more than 102 (38). Temp rise less than
that usually doesn't cause rigors.
7. Chronic infections (unless widely disseminated), some acute
infections causing slow rise in bacteremia like typhoid/Brucella etc
unless complicated by abscess etc usually doesn't cause rigors.
