The benefits of a fever TB Nedarim 41

Sometimes modern science repudiates the medical advice or practice found in the Talmud (I’m thinking about the benefits of bloodletting). Sometimes modern science supports an ancient practice. I appreciate the blog talmudology.com by Dr. Jeremy Brown because it honestly discusses science and medicine in the Talmud. I always learn something from this blog and encourage you to subscribe. Rava teaches that a fever is beneficial in today’s daf TB Nedarim 41 and the blog supports his contention.

First Rava’s observation. “Rava said: With regard to this fever [ishta], were it not the agent [parvanka] of the Angel of Death, i.e., the cause of serious, potentially deadly illnesses, it could be deemed beneficial, like thorns for palm trees, as the thorns prevent people and animals from touching and ruining the dates. The fever is advantageous if its incidence is once in thirty days, and it is like an antidote [tiraiki] for poison in the body.” (Sefaria.org translation)

Whenever I have a fever, my first inclination is to take Tylenol to reduce it. Dr. Brown’s teaches that this is not the best course of action for neither adults nor children.

“It's not just people who get fevers. Dogs and cats do too, as do mice (and all mammals), reptiles, and even goldfish. Why would so many animals respond to an infection by developing a fever?

THEBENEFITS OF FEVER

The reason is simple. The immune system fights infections better when the body is hotter. The way it does this is now well-understood but very complicated; here are just the highlights. 

Under what immunologists call "thermal stress" (and the rest of us call "a fever,") neutrophils, the white cells that are needed to fight infection, are released in greater numbers from the bone marrow. These neutrophils also do a better job of fighting bacteria at the siteof the infection when the body is warmer.  Fever also improves the killing ability of another group of blood cells called natural killer cells, and it increases the ability of the macrophages to ingest and destroy the invading bacteria. In an excellent review of fever and the thermal regulation of immunity in Nature Reviews, the authors concluded that "[t]he picture that emerges is one in which febrile temperatures serve as a systemic alert system that broadly promotes immune surveillanceduring challenge by invading pathogens."  

So your body does a better job of fighting bacteria when it is hotter.  Why then, do doctors give medicines that reduce a fever?  Good question. The truth is, they really shouldn't.

DON'TREACH FOR THAT TYLENOL/PARACETOMOL/ACAMOL 

 

If you are the parent of a child with a fever, you are likely to give your sick offspring a medicine that interferes with the immune system, like Tylenol if you are in the US, Paracetamol if you are in the UK or South Africa, or Acamol in Israel (though they are different words for the same medicine).  But if, as we have seen, the body does a better job of fighting infection when it is a few degrees hotter, might reducing the fever lead to a worse outcome for the child?

Thisquestion was recently examined by a group from McMaster University in Canada. They looked at the side effects of reducing a fever in those who are sick from a population level. What happens in a large group of people when some of them - infected with, say, influenza -take medicines to reduce their fever? The answer is that more of them transmit the virus and so more of them fall ill.  On a population level the effect is rather drastic:

Putting together our estimates of the treatment probability p and the individual transmission enhancement factor fi ...we conclude that the current practice of frequently treating fevers with antipyretic medication has the population-level effect of enhancing the transmission of influenza by at least 1% (95% CI: 0.04–3%)...This estimate does not take into account the known effect that the infectious period of influenza is also increased by antipyresis, nor does it take into account the potentially large effect of increasing the rate of contact among infectious and susceptible individuals because antipyresis makes infectious individuals feel better...To put our lower bound...into perspective, consider that approximately 41,400 ...deaths per year are attributed to seasonal influenza epidemics in the United States (and an order of magnitude more worldwide). Taken at face value, our results indicate, for example, that...at least 700 deaths per year ... could be prevented in the US alone by avoiding antipyretic medication for thetreatment of influenza...

“In the absence of meaningful evidence for the beneficial effects of fever reduction, the commonplace reduction of fever in critically ill patients must be called into question.

— Ryan and Levy. Clinical Review: Fever in intensive care patients. Critical Care 2003, 7:224.

The Canadian investigators concluded that"...the use of antipyretics can have subtle and potentially importantnegative effects at the population level. Any medical intervention that aims torelieve the symptoms of an infectious disease in an individual should also be evaluated in light of potentially harmful effects at the populationlevel..." And it's not just populations that can suffer; individual patients are at risk too. In a 2011 paper looking at the treatment of fever in very ill patients with sepsis in the ICU,  a French team looked at the beneficial and detrimental effects of fever, and concluded that "...the widespread use of antipyretic methods in ICU patients is not supported by clinical data and fever control may be harmful, particularly when an infectious disease is progressing..."

 

 From Lainey Y. et al. Clinical review: Fever in septic ICU patients - friend or foe? Critical Care 2011:15:222” (talmudology.com)