Does TB (Tuberculosis) spread through housefly like Muska-Domestica?

This possibility can be tested and as far as I know it has not. So, here I propose the study that may provide an answer to your question:

Arrange to have a set number of flies in a jar that is covered with a cork that contains an input and output tubes. To the input tube, pass a given volume/time containing a given mixture of colony forming units of a relatively safe mycobacterium (ex M smegmatis). The out put tube should contain a suitable plug that can act as filter to trap the bacterium. At given intervals, evacuate gas contents of the tube via the out-put tube. The flies can be knocked out with chloroform, collected, counted, homogenized, diluted for colony forming units and the homogenate plated unto a suitable solid medium that supports mycobacterial growth. The results are of course highly preliminary but if indeed colony forming units are obtained, then a more precise type of experimental protocol may be pursued. If indeed mycobacteria can be recovered, it does not mean that the fly acts as a reservoir for the mycobacterium, etc. You asked the question, now consider looking for an answer.

Interesting and practical answer, dr. Amaral.

I suppose also that if the contaminated flies walked around in the (dusty) cage of an animal then this animal actually got infected, there would be a good proof (although a negative result wouldn't necessarily prove the opposite).

I cannot see why the flies couldn't vehiculate this germ (as they carry many other). The only particularity may be that they would spread the germ on to objects from which the M.T.should be raised into the air and breathed in order to infect.

Perhaps the probability of infection by this way is smaller, because:

- the number of bacteria (infectious charge) is much smaller comparing to the cough

- these bacteria get even more 'diluted' in the environment as the fly wouldn't 'leave' all of them in a single spot

- the dicrease/dilution of the infectious charge diminishes also the probability of germs being inhaled in sufficient qty.

However, due to the resistance of MT in the environment and the relatively small infectiuos charge needed for an infection, it is not unreasonable to complete the hygienic measures by reconfirming the control of flies, especially in high risk areas.

I will look for further information too.

mechanical transmission may be a possibility. load of the bacteria by the flies for the spread of the disease may be a limiting factor. However, control of flies contribute to the control of other health problems any way. lalitha kabilan

Actually I've read some articles on transmission of infection diseases through flies. Mostly of them are considered TB as an example of a disease transmitted though flies. But still I don't have any document regarding this type of transmission mechanism of TB. Answers provided by Sir Leonard Amaral and Blake Jane are interesting.

Thank you all

Not possible. No report like that, so far.

Interesting question!

I dont think house-fly can transmit Mt, since house fly is not inhaled or eaten by humans. Even in case of possible mechanical transmission, what volume or colony of Mt can a single house-fly convey at once that will not have lead to the death of the same house-fly.

Because the quantity of bacteria is few and there is little chance (risk) to inhale it that way, and other reasons that Dr. Blake Jane mentioned, I think it is not possible. But testing it as Dr. Leonard Amaral proposed, will be interesting and useful.

Graham-Smith in Flies in Relation to Disease (1914) has 4 pages summarising experimental data, eg  "Lord (1904) made a number of careful investigations. In one experiment he placed about 30 flies in an inverted jar together with a small dish containing tubercular sputum...".

He concludes:"The experiments quoted, however, conclusively indicate that flies may carry B.tuberculosis, and distribute it for several days after feeding on infected material. No doubt under suitable conditions they frequently infect articles of food..."

Hofman (1888) appears to be the only observer who has examined 'wild flies' for the presence of tubercle bacilli. He examined six flies caught in the room of a tuberculous patient and found acid-fast bacilli in four of them..."

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My attention was redirected to this idea as I was listening to a lecture on badgers and TB this morning. There is a very close correlation and strong clustering between TB strains in cattle and their neighbouring badgers. I cannot see any obvious easy two-way transmission mechanism between these two species, unless it is through flies. It is therefore extremely disappointing that the whole relevant literature on this topic apparently comprises 4 flies in over a century.

Maybe that is possible, but I am not sure how many Mycobacterias is necessery for TBC infection??

But the dogs can make massive make the transmission of TBC tubercular sputum from the street on the tongue!

The contact with birds and their excrets is the way for transmission for Mycobacterium avis!

Today the Lympahadenitis colli specifica (TBC) has the name LYMPHOMA HODGKINS, only pathohytologically, without any bacteriological examination of  s.c. "Lymphoma"...!?

"Maybe that is possible, but I am not sure how many Mycobacterias is necessery for TBC infection??"

The idea of a sufficient dose is a valid consideration.   However, it should not be overlooked that flies could transfer a small dose of germs to some suitable intermediate culture medium, where they can greatly multiply.   There probably also protected areas and niches in the body out of reach of the body's defense mechanisms.

I agree Anthony. And then all dependence from  imunological status of body, too.

But the bacteriological investigation of tissue must be primary, or in the same time with pathohystology.

Yes, It is possible. TB can spread through fomites. Immuno-compromised individuals are at more risk for TB.

Have a look at this useful RG link.

Though Musca domestica is a mechanical vector of pathogens like bacteria, fungi, viruses, and parasites, some of which can cause serious diseases in humans and domestic animals. But yet there is no evidence that it helps in transmission of mycobacterium tuberculosis.