Date posted: February 27, 2012

On the Genus Epidemicus
One of the more overlooked topics in contemporary homoeopathy is the prophylactic treatment of acute epidemic disease. Yet a review of homoeopathy’s 200-year history reveals that this is an arena in which we have seen some of the greatest examples of the effectiveness of our art and science.

Hahnemann on homoeoprophylaxis
We don’t have to search far in the historical record to find examples of the effective use of homoeoprophylaxis.

In 1799 – 3 years after the “birth” of homoeopathy in Hahnemann’s landmark article Essay on a New Principle – Samuel Hahnemann achieved fame throughout Europe from his exceptionally effective treatment of a Scarlatina epidemic that was sweeping Germany. He wrote:

“I resolved in this case of scarlet fever just in the act of breaking out, not to act as usual in reference to individual symptoms, but if possible (in accordance with my new synthetical principle) to obtain a remedy whose peculiar mode of action was calculated to produce in the healthy body most of the morbid symptoms which I observed combined in this disease.

My memory and my written collection of the peculiar effects of some medicines, furnished me with no remedy so capable of producing a counterpart of the symptoms here present, as Belladonna.”

Hahnemann published this pamphlet Cure and Prevention of Scarlet Fever in 1801. At the time he promoted Belladonna as a specific prophylactic remedy for Scarlatina – and accompanying each pamphlet sold, was a vial of Belladonna prepared according to his technique at that time.

With increased experience observing and treating epidemic illnesses, Hahnemann recognized the unique nature of each occurrence of an epidemic. Aconite proved to be the specific for a subsequent Scarlatina epidemic sweeping Germany between 1800 and 1808.

In an 1808 paper (Observations on the Scarlet Fever), Hahnemann provided a careful description of the individualizing aspects of these two epidemics. This individuality of epidemic occurrences had not escaped other observers.

In one of his rare words of praise for other physicians, Hahnemann wrote: ”Only the honest Sydenham perceived this, for he insists … that no epidemic disease should be taken for any previous one and treated in the same way, since all that break out at different times are different from each other.”

Three approaches for homoeoprophylaxis
Three approaches may be used to select the remedy for prophylaxis of a prevailing epidemic. All have their roots in classical practice, but it is the selection of a genus epidemicus – an individually selected remedy for this particular outbreak of an epidemic – which is to be sought as the surest and most closely aligned with our guiding principles.

The first of these is the use of the disease nosode in prophylaxis. Examples would be the use of Influenzinum in flu prophylaxis or Morbillinum in a measles epidemic. Closely related to this would be the use of the sarcode Anas barbare hepatis et cardus extractum (liver and heart of the Barbary duck) for ‘flu. Derived from tissues of the native host of influenza, this remedy is prepared from tissue containing and reacting to the influenza virus.

The nosode represents the undifferentiated or generic appearance of an acute miasm, not accounting for individual variability of persons or individual epidemic occurrences. Its routine use in active disease would be considered isopathy rather than homoeopathy; and historical experience reveals the general inadequacy of this approach.

However, in prophylaxis, this may be a successful strategy in a pinch, particularly early in the epidemic of an acute miasmatic illness, before a genus epidemicus – the specific remedy for the individual epidemic – has been identified. Following Hering’s introduction of nosodes into our Materia Medica, Boenninghausen experimented early on, with considerable success, at using Variolinum (the smallpox nosode) for the prophylactic treatment of smallpox.

The second approach is to select a remedy deemed central to the undifferentiated or generic nature of the epidemic illness. This is done by taking an anamnesis of the disease-as-named, without specific attention to the individuality of the prevailing epidemic or the individuality of a specific case. Examples might include Drosera for whooping cough or Eupatorium perfoliatum for influenza.

Here again the individual nature of the particular epidemic is not taken into account, and this approach works best with those epidemic illnesses that can be termed acute miasms ones in which there is less variability in individual expression. Hahnemann in this manner suggested Camphora as the homoeoprophylaxis simillimum for the approaching epidemic of Asiatic cholera. Boenninghausen had some excellent success in using Thuja occidentalis in this manner in the prophylactic treatment of smallpox.

This of course can only be done for those diseases that Hahnemann would class as “acute miasms” – diseases that “recur in the same manner and are therefore known by a traditional name”. As an example, we could look at Scarlatina (scarlet fever), much as Hahnemann himself did in 1799 in Konigslutter.

The success of the two approaches outlined above – the use of the acute-disease nosode, and the identification of a genus remedy for the acute miasm – may hinge on the temporal behavior of acute illnesses. In their earliest stages, these diseases are often ill defined, or generic in appearance; in flu, there is a mild poorly-defined malaise with confusion in temperature regulation; in measles, fever with morbiliform rash on the forehead and mild coryza; etc. As the individual case of disease evolves, differentiating features then appear which further characterize the case and point to an individually specific simillimum; but early on, this less-differentiated disharmony may respond to a remedy bearing more generic similarity.

When a remedy specific to the individual occurrence of an epidemic – the genus epidemicus- is identified, this remedy will act more surely in homoeoprophylaxis and early treatment of cases, and is to be preferred to the approaches described above.

This genus epidemicus may often become clear following the treatment of 5-6 cases in a particular epidemic; though it may require additional cases to obtain a clear picture, particularly when the situation is complicated by the presence of more than one viral illness moving through the community. This remedy will not only be useful in prophylaxis, but will often be the simillimum to developed cases of the acute disease.

Finding the Genus Epidemicus
Hahnemann describes the process of determining the genus epidemicus concisely, in his Organon:

Aph. 101:
Usually the physician does not immediately perceive the complete picture of the epidemic in the first case that he treats, since the collective disease reveals itself in the totality of signs and symptoms only after several cases have been closely observed. Nevertheless, an observant physician can often come so close after seeing only one or two patients that he becomes aware of the characteristic picture of the epidemic and can already find its appropriate homoeopathic remedy.

Aph. 102
From writing down the symptoms of several cases of this sort, the outline of the disease picture becomes more and more complete – not more extensive and wordy, but more characteristic, containing more accurately the peculiarity of the particular collective disease. The ordinary symptoms – e.g., loss of appetite, sleeplessness, etc. – become more precisely qualified, and those that are more exceptional, special, and, in the circumstances, unusual, and belong to only a few diseases, reveal themselves and constitute the characteristic picture of this epidemic.

All those who catch an epidemic at a particular time have a disease flowing from the same source and therefore the same disease. But the entire scope of such an epidemic disease, the totality of its symptoms (which we need to know in order to grasp the whole disease picture and choose an appropriate remedy for it) cannot be perceived in any one patient, but can be fully distilled and gathered only from the sufferings of several patients with different physical constitutions.

Potency and dose
Potency and dosage for prophylactic treatment are guided by the same issues that guide the treatment of acute disease; largely, the dynamic nature of the illness, the vitality and sensitivity of the individual patient, and, most importantly, what you happen to have on hand at the time. In general, the lower potencies suffice. Commonly used potencies are 12C or 30C, occasionally 200C, and on rare occasions 1M potencies are used in prophylaxis.

It’s ideal to give the remedy in repeated doses of gradually ascending potency in medicinal solution. A typical regimen for a highly virulent disease such as scarlatina (for the patient of average vitality and sensitivity) would be to put 1 pellet of 12C, 30C or 200C in 1 ounce of distilled water in a small dropper bottle; and dose 2 drops daily, after 4 succussions of the bottle, for the duration of the epidemic in the community. An alternative is to use 1 pellet in 4 oz distilled water in a larger bottle, with a 1/2 tsp dose after 4 succussions. Dosing is reduced in patients judged of lower vitality and/or higher sensitivity.

This frequency of repetition has as much to do with the pace of the disease and the (similar) pace of the remedy as it does with the duration of the epidemic. Scarlatina generally has a rapid and furious pace, calling for a simillimum (e.g., Belladonna) with a matching pace and more limited duration of action. Influenza more often has a more indolent pace, calling for a simillimum of matching slow pace (e.g., Bryonia, Gelsemium) and longer duration of action. There are no recipes here which can be followed in cook-book fashion; rather, consider the dosing directions above as examples, and allow yourself to be guided more by your clinical experience in homoeopathic treatment for the cases at hand.

When the genus epidemicus does not fit the case
The genus epidemicus may fail to act – both prophylactically and in treatment of active epidemic disease – when the reaction of the patient is dictated more by the pre-existing chronic disease of the patient than by the virulence of the acute miasmatic organism.

We might imagine (somewhat simplistically) that the direction a disharmony takes in any particular case of disease is a balancing act between the direction a morbific influence is trying to push us, and the direction in which we are naturally inclined to fall.

For most of the population, it seems that the ‘flu’ virus is a virulent-enough agent that we mostly fall ill in the same manner, in relative disregard to our individual situations. But for those whose dynamis is occupied with an active chronic disease, the reaction to the ‘flu’ virus may have more to do with the disharmony of that pre-existing disease of the person than it does with the reaction that the rest of the population experiences to the virus.

Consequently, their ‘flu’ is unique, and does not bear similitude to the genus epidemicus that prevails in the larger community. If their chronic disharmony can in its own individual manner embrace the disharmony invited by the ‘flu virus’, the ‘flu’ takes on an individual character in that patient.

If the chronic disharmony of the patient is sufficiently dissimilar to the demands made by the virus, the patient may even be “protected” from this acute illness by their chronic dissimilar disease. We all have seen cases like this, where our patient is impressed that they have avoided colds and flu for the past several years, despite being debilitated by (e.g.) chronic rheumatoid arthritis.

For individuals with active chronic disease, the most effective strategy for epidemic prophylaxis may be to treat with the simillimum for the pre-existing chronic disease of the patient, rather than focusing on the acute disease as it is seen in the remainder of the community.

Kent introduced the notion that all acute disease is predicated on psora (pre-existing chronic disease); though it is difficult to determine how this belief affected his actual clinical practice in the treatment of acute disease. Kent’s assertion would suggest that acute diseases do not occur for those in perfect health – certainly a radical concept, and one that is at clear variance with Hahnemann’s views and observations on the matter.

The notion that we can address acute disease adequately by always focusing exclusively on the chronic is one that has found its way into contemporary homoeopathy as well as into many contemporary “new age” medical philosophies. In the prophylaxis of acute epidemic disease, when are we best to focus on the epidemic and when is it more appropriate to focus on the chronic?

Some suggest that we should always give the chronic remedy in acute disease. Is there always a chronic remedy indicated or identifiable for the person who appears to be in previously good health? When chronic disease is present, does it always dictate the direction of acute illness?

When and who to treat prophylactically?
At first glance it might seem appropriate to treat everyone – or anyone who desires it – prophylactically for such epidemic acute illnesses as whooping cough, scarlatina, mumps, influenza, etc. when these measles, visit the neighborhood. However, on greater reflection, there may be some concerns with doing this.

Is there value to our system in spontaneously going through an acute disease? Does the immune system benefit from the experience of sustaining us through measles? Will prophylaxis of chickenpox as a child open us to the risk of contracting this disease as an adult, when it is of much greater concern? Are some of these acute expressions of disease opportunities for the system to throw off a chronic miasmatic burden that might otherwise contribute to chronic degenerative disease? Does homoeoprophylaxis interfere with the dynamis’ response to an acute morbific influence, or does it assist us in making a more balanced response, permitting us any benefits of the experience but tempering the process so that this is done without dis-ease?


  1. For a definition of acute disease and its variations – sporadic and epidemic disease, and acute miasms – see Hahnemann’s Organon of Medicine, aph. 73
  2. Cure and Prevention of Scarlet Fever, Samuel Hahnemann (published as a pamphlet, Gotha, 1801); and in The Lesser Writings of Samuel Hahnemann, R.E. Dudgeon.
  3. Observations on the Scarlet-Fever, Samuel Hahnemann, no. 160, 1808; and in the Lesser Writings of Samuel Hahnemann, R.E. Dudgeon 4.  Organon of Medicine; Samuel Hahnemann; Footnote b to aphorism 81
  4. Cause and Prevention of the Asiatic cholera; Samuel Hahnemann; and in The Lesser Writings of Samuel Hahnemann, R.E. Dudgeon
  5. Concerning the Curative Effects of Thuja in Small-pox, Clemens Maria Franz, baron von Boenninghausen;; and in The Lesser Writings of Boenninghausen, L.H. Tafel trans
  6. Organon; Samuel Hahnemann: aphorism 73
  7. Genus Epidemicus; Dr. Will Taylor MD, 2002
  8. Suggestions for the prevention of epidemics in general, especially in towns; Samuel Hahnemann, no. 212, 1808; and in The Lesser Writings of Samuel Hahnemann, R.E. Dudgeon


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