Diseases and Cures in the Wings of Houseflies

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Electron micrograph of bacteriophages attached to a bacterial cell.

This article analyzes the claim that the sahih hadiths concerning the wings of the housefly are scientifically accurate.

Apologetic Claim

The thesis put forward is that it has recently been proven by modern science that flies carry not only pathogens but also the agents that limit these pathogens, thus proving the fly wing hadiths (as narrated from Abu Hurayra and Abu Sa`id al-Khudri by al-Bukhari and in the Sunan):

The Prophet said "If a house fly falls in the drink of anyone of you, he should dip it (in the drink), for one of its wings has a disease and the other has the cure for the disease."

They principally identify these agents to be bacteriophages, though they also sometimes refer to fungi.


Bacteriophages (“phages”) are viruses that infect bacteria. It is a generality that all natural bacterial populations are limited by phages and environmental conditions, but it is a leap to suggest that these elements are antidotes. Mammals, too, are limited by pathogens, but it is foolish to suggest these pathogens are antidotal to mammals. Nevertheless, a dissection of the fly wing hadiths is as follows:

Which wing contains the venom and which the antidote?

Ibn Hajar wrote in his commentary on the hadith:

I found nothing among the variants to pinpoint the wing that carries the antidote but one of the Ulema said he observed that the fly protects itself with its left wing so it can be deduced that the right one is the one with the antidote.

This statement is evidently mistaken, but is also what must be the starting point in debating on this subject. For if they say that the presence of phages proves that the hadith is correct, then pointing out that phages are not limited to any one wing, right or left, immediately proves the falsehood in the hadiths.

Making erroneous assumptions

A. It is assumed that bacteriophages are antidotal to bacteria. Bacteriophages cause lysis of their bacterial hosts in the final stage of infection – thereby releasing new phage particles to infect other bacterial cells in the population. However, in the natural environment, this state is equilibrial – meaning that only a small proportion of bacterial cells is infected at any one time. Just like only a small proportion of humans is ever infected with the flu virus at any one time (except in a pandemic).[1]

B. It is assumed that flies must carry the antidote to the pathogens they carry.

… from the perspective of logic, if the fly did not carry some sort of protection in the form of an antidote or immunity, it would perish from its own poisonous burden and there would be no fly left in the world.

Flies do not succumb to human pathogens – they are merely carriers. This shows that those who make these claims do not understand pathogenesis. Flies do not succumb to human diseases.

The way it works is as follows:

  • Fly lands on feces or rotting carcass – transfers traces of feces or rotting carcass onto itself.
  • Fly lands on human food – transfers traces of feces or rotting carcass onto human food.
  • Fly flies away – human consumes contaminated food and becomes sick.
  • Fly continues on as normal, free to repeat the cycle again.

C. It is assumed that these relations that do not exist.

The existence of similar bacteria-killing mechanisms in two bacteriophages suggests that antibiotics for human infections might be designed on the basis of these cell wall-destroying proteins. Science 292 (June 2001) p. 2326-2329.

The ability to design antibiotics that might utilize bacteriophage infection pathways does not prove that phages are antidotal to bacteria. Antibiotics are not phages. Further, these antibiotics are likely to be ‘artificial’ and do not reflect the natural state of fly-human disease interactions.

Making erroneous claims

Only in modern times was it discovered that the common fly carried parasitic pathogens for many diseases including malaria, typhoid fever, cholera, and others. It was also discovered that the fly carried parasitic bacteriophagic fungi capable of fighting the germs of all these diseases.

There are two mistakes here:

A. The common fly does not carry malaria – that is carried by and transmitted exclusively through the bites of Anopheles mosquitoes.[2]

B. There is no such thing as bacteriophagic fungi. This term may sound impressive to non-scientists, but bacteriophages are viruses and fungi are simply fungi.

Quoting erroneous scientific articles

These fly microbiota are bacteriophagic or "germ-eating". Bacteriophages are viruses of viruses. They attack viruses and bacteria. They can be selected and bred to kill specific organisms. The viruses infect a bacterium, replicate and fill the bacterial cell with new copies of the virus, and then break through the bacterium's cell wall, causing it to burst. The existence of similar bacteria-killing mechanisms in two bacteriophages suggests that antibiotics for human infections might be designed on the basis of these cell wall-destroying proteins. Science 292 (June 2001) p. 2326-2329.

A. Bacteriophages do not attack other viruses.[3]

B. Not all bacteriophages encode cell-wall destroying proteins to lyse host cells.

Misinterpreting scientific facts

Gnotobiotic [=germ-free] insects (Greenberg et al, 1970) were used to provide evidence of the bacterial pathogen-suppressing ability of the microbiota of Musca domestica [houseflies] .... most relationships between insects and their microbiota remain undefined. Studies with gnotobiotic locusts suggest that the microbiota confers previously unexpected benefits for the insect host.

This states that the microbiota of insects protect them from their (i.e. insect) pathogens. It does not say anything about human pathogens carried by insects.

An article in Vol. 43 of the Rockefeller Foundation's Journal of Experimental Medicine (1927) p. 1037 stated: The flies were given some of the cultured microbes for certain diseases. After some time the germs died and no trace was left of them while a germ-devouring substance formed in the flies - bacteriophages. If a saline solution were to be obtained from these flies it would contain bacteriophages able to suppress four kinds of disease-inducing germs and to benefit immunity against four other kinds. Cited in `Abd Allah al-Qusami, Mushkilat al-Ahadith al-Nabawiyya wa-Bayanuha (p. 42).

This has just proven the existence of bacteriophages. What it has not proven is whether these bacteriophages protect humans against human pathogens carried by flies.

Extending claims inappropriately

The fly microbiota were described as "longitudinal yeast cells living as parasites inside their bellies. These yeast cells, in order to perpetuate their life cycle, protrude through certain respiratory tubules of the fly. If the fly is dipped in a liquid, the cells burst into the fluid and the content of those cells is an antidote for the pathogens which the fly carries." Cf. Footnote in the Translation of the Meanings of Sahih al-Bukhari by Muhammad Muhsin Khan (7:372, Book 76 Medicine, Chapter 58, Hadith 5782).

Now it is not only phages on the right wing, but the yeast cells inside fly stomachs and respiratory tubules. We assume it is the yeast antibiotics they are referring to. The presence of tiny amounts of antibiotics (produced by fungi) does not protect humans from enteric diseases. Apologists are confused about antibiotics – they do not understand how antibiotics work. Dosage is important. Modern antibiotics are artificial and highly purified. Treatment of bacterial infections involves massive doses of purified antibiotics that are not found in the natural environment.

Confusing the use of bacteriophage

Bacteriophagic medicine was available in the West before the forties but was discontinued when penicillin and other "miracle antibiotics" came out. Bacteriophages continued to flourish in Eastern Europe as an over-the-counter medicine. The "O1-phage" has been used for diagnosis of all Salmonella types while the prophylaxis of Shigella dysentery was conducted with the help of phages. Annales Immunologiae Hungaricae No. 9 (1966) in German.

A. The O1-phage is used for typing (i.e. diagnosing) Salmonella infections, not treating it.[4]

B. Bacteriophage therapy was subsumed by antibiotic therapy in the 1940s because it was largely ineffective. Before antibiotics, physicians were desperate for cures – they would try anything, even bacteriophage therapy – but that does not prove bacteriophage therapy works. In any event, one would need massive doses of phages to treat each case – which does not occur in the natural environment. A fly dipping its right wing, left wing, or its entire body, will not be sufficient.

Failure to understand what is purported as proof

However, researchers in eastern Europe, including the former Soviet Union, continued their studies of the potential healing properties of phages. And now that strains of bacteria resistant to standard antibiotics are on the rise, the idea of phage therapy has been getting more attention in the worldwide medical community. Several biotechnology companies have been formed in the U.S. to develop bacteriophage-based treatments - many of them drawing on the expertise of researchers from eastern Europe." http://www.sciencefriday.com/pages/2000/Jul/hour1_072100.html

A. This article they quote and link to highlights one of the main limitations of bacteriophages in therapeutics, i.e. it is rapidly taken up by the human body and destroyed in human spleen cells. Therefore, even when a fly should carry bacteriophages, normal human physiology precludes these phages from acting as antidotes.

B. Even if some biotechnology companies want to develop bacteriophage-based treatments, it does not prove the hadith to be correct. These bacteriophage-based treatments involve the use of genetic engineering and other advanced scientific techniques to utilize bacteriophage pathogenesis for the treatment of human diseases. Naturally-occurring bacteriophages are useless for this purpose.

Ignoring non-bacterial enteric diseases

Even if the wings of flies were to provide humans with an antidote to bacterial diseases, they could possibly infect humans with another non-bacterial disease. Flies also spread pinworm, tapeworm, viral gastroenteritis, amebic dysentery, giardia enteritis, and enteric hepatitis. Bacteriophages and fungi are totally ineffective against these diseases.


The scientific evidence does not support the veracity of the fly wing hadith for the following reasons:

1. Contrary to innovative interpretations of relevant hadith, bacteriophages are not limited to any specific wing of the fly.

2. Contrary to innovative interpretations of relevant hadith, bacteriophages in the natural state and concentration are not antidotal to bacterial diseases, particularly for temperate or lysogenic phages.

3. Bacteriophages are ineffective against non-bacterial diseases carried by flies, meaning even if the wings were to provide you with an antidote to bacterial diseases, they could infect you with another non-bacterial disease (i.e. dipping a fly into your drink is not good advice).

4. Phage therapy is not a generally-accepted medical therapy at present because it is largely ineffective and requires large quantities of purified, possibly genetically-engineered, phages not present in the natural condition.

Responses to Apologetics

  1. According to Nature.com, it has been discovered that "Insect wings shred bacteria to pieces."
    The article in question is referring to the wings of a cicada.[5] A cicada is not the same thing as a house fly. Cicadas are related to locusts and crickets which are vegetarian unlike the excrement friendly housefly. If you examine a housefly wing under a microscope you will see that a housefly's wing structure is different to that of the cicada's wing. The housefly wing is smoother and has fine hairs which are curled downwards not like the upward pointing spikes of the cicada.

See Also

  • Health - A hub page that leads to other articles related to Health

External Links

Resources on Bacteriophage Biology

A good general introduction to bacteriophage biology can be obtained from the internet, including the following:


  1. Stephen T. Abedon, "An Expanded Overview of Phage Ecology", Ohio State University at Mansfield Bacteriophage Ecology Group, January 1, 2002 (archived), http://www.mansfield.ohio-state.edu/~sabedon/bgnws011_submission.htm. 
  2. "Malaria", World Health Organization Media Centre, Fact sheet No. 94, Reviewed March 2013 (archived), http://www.who.int/mediacentre/factsheets/fs094/en/. 
  3. Dr. Gary Kaiser, "The Lytic Life Cycle", Community College of Baltimore County, January 16, 2002 (archived), http://web.archive.org/web/20060522093342/http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/viruses/lytlc.html. 
  4. "Typing of Salmonellae", Avinash Abhyankar, Internet Archive capture dated October 27, 2009 (archived), http://web.archive.org/web/20091027101854/http://www.geocities.com/avinash_abhyankar/typing.htm. 
  5. Trevor Quirk, "Insect wings shred bacteria to pieces", Nature, March 4, 2013 (archived), http://www.nature.com/news/insect-wings-shred-bacteria-to-pieces-1.12533.