WO2006054108A1

WO2006054108A1 - Maggot delivery system

Info

Publication number: WO2006054108A1
Application number: PCT/GB2005/004472
Authority: WO
Inventors: Stephen Thomas; Anthony Fowler; Alan Morgan
Original assignee: Zoobiotic Limited
Priority date: 2004-11-20
Filing date: 2005-11-18
Publication date: 2006-05-26
Also published as: GB2422315B; GB0523465D0; EP1835943A1; GB2422315A

Abstract

A maggot pouch (1) which has foraminous portion (4). The foraminous portion (4) has apertures which are of a dimension such that maggots can pass through the foraminous portion from the inside to the outside of the pouch so that the maggots can come into contact with a wound.

Description

Maggot Delivery System

The present invention is concerned with a maggot delivery system and in particular but not exclusively to a dressing or a bandage for the treatment of wounds.

This application system also provides actively feeding maggots with the facility to remove themselves from the immediate vicinity of the wound during certain stages in their feeding cycle.

For treatment of wound and infections, especially wounds that contain dead tissue (such as the treatment of gangrene) , it has been known for many years to use fly larvae. Particularly preferred larvae include fly of the genus Lucilia (Greenbottle flies) . It is typical to apply the larvae to a wound containing dead tissue for a few days. It has been shown that maggots in this time will remove necrotic tissue in the wound, eliminate bacterial infections and stimulate healing of the wound.

Maggots are typically applied through local application of ^Λloose' or 'free' maggots to the wound. The larvae are applied to the wound and covered with a dressing to prevent the larvae escaping. However, this is disadvantageous, as the maggots are difficult to apply.

It is therefore an aim of the present invention to alleviate at least some of the disadvantages identified above.

It is a further aim of the present invention to provide and method and apparatus for the application of maggots to a wound.

It is important that the maggots are able to gain access to the recesses of a wound to ensure complete cleaning.

It has been widely acknowledged that the secretion from the maggot, in particular digestive secretions, assist in the 'cleaning' of a wound; however, it has been found that the movement of the maggots within the wound also assist in 'cleaning' and subsequent healing of the wound.

In addition observation of the feeding activities of maggots has revealed that, given the opportunity, they will remove themselves from their food source for significant periods at intervals during their feeding cycle. During these times they seek out an environment which provides protection from potential predators. Full grown maggots that have ceased feeding will tend to remain within a pouch or bag and thus facilitate removal at the time of dressing changes.

It is therefore a further aim of the present invention to provide maggots with the facility to remove themselves from the wound which provides a source of food, when required. This facility is provided by the inclusion within the pouch or bag of a suitable media that provides a shelter or a rest area which the maggots can move to. The media, by way of example could include an open cell foam, layers of gauze or nonwoven fabric, or small pieces or chips of foam which when in close proximity provide a series of interconnected channels into which the maggots may enter. Therefore, according to a first aspect of the present invention, there is provided a maggot delivery system which includes a pouch having at least one foraminous portion, the foraminous portion having apertures dimensioned to permit a maggot or maggots when contained in the pouch to pass through the foraminous portion.

The maggots typically are initially permitted to pass through the apertures from the inside of the pouch to the outside of the pouch and this may be provided by the foraminous portion being provided as a mesh or a net type layer.

Alternatively, the foraminous portion may comprise a foam having apertures that are sufficient to permit the passage of maggots therethrough.

It is envisaged however, that the foraminous portion may be formed as a combination of a mesh, a net or a foam.

In a preferred arrangement, the outer surface of the bag may have a membrane attached to it. The membrane is permeable to water vapour but keeps solutions present in proximity to the wound in place. The solutions include the secretions produced by the maggots when active in the wound and also body fluids produced as a result of an inflammatory response. These secretions including those generated by the maggots include enzymes and other agents that prevent the multiplication of bacteria in the wound area. Maintaining these enzymes agents in proximity to the wound increases the activity and efficiency of the maggot delivery system of the invention. It is therefore desirable and advantageous to permit maggots to move freely within the wound.

Furthermore, the use of a pouch to deliver maggots to a wound according to the present invention is particularly advantageous over one of ^λfree' maggots as it is much easier to apply to a wound. The pouch may also form an integral part of a larger outer retention layer which is attached to the periwound skin to form an enclosure from which the maggots cannot escape.

Preferably, each aperture within the pouch has a diameter of greater than about 400μm, further preferably greater than about 500μm. According to a particularly preferred embodiment, each aperture has a diameter of at least 600μm.

It is envisaged that an array of differing sized apertures may be used, with the largest apertures at a position in the foraminous material (for example the centre) so that the maggots can be channelled to the deepest part or most infected part of the wound.

Although the foraminous portion allows passage of maggots to the wound, there are also apertures that permit passage of maggots back to the pouch if required.

It is envisaged that the apertures may have arrangements which only allow one way movement of a maggot i.e. either to or from the wound; this may be provided for example by having flaps that permit outward movement from the pouch but which close if the maggot tries to move back to the pouch.

Although the foraminous layer is generally flexible, the pouch itself may also be formed of a substantially- flexible material. However, the foraminous layer may be inflexible or have areas of inflexibility. It is possible that the remainder of the pouch is a foraminous layer where the apertures are dimensioned to substantially prevent maggots contained in the pouch from passing therethrough. Preferably, the remainder, or at least areas of the pouch are gas permeable to increase longevity of maggots contained in the pouch.

It is a further desirable feature of the invention that the pouch contains a material which provides a three dimensional porous structure that provides shelter to the maggots.

The pouch may be manufactured from a range of materials. Biodegradable materials may be used such as cellulose. Further, materials such as gelatine, which again is biodegradable could be used. Alternatively, material such as nylon or a polyester, polyethylene or polypropylene may be used as can other polymeric material. It is envisaged that a mix of materials may be used, for example if a wound is positioned, at an exposed area of the body a polyethylene material could be used to limit wear on the bag.

If the wound is at a sensitive area of the body, for example under the arm, where chaffing may occur, then cellulose may be used to form the bag, either alone or in combination with another material such as a polymer. It is preferred that a "soft" and flexible material is used in areas where chafing can occur. Preferably, the pouch further includes a removable layer arranged to cover the foraminous portion. Advantageously, the removable layer substantially prevents maggots contained in the pouch from passing through the foraminous layer until desired by the end user. The removable layer is typically of a semi permeable material or it may be of a fine mesh like layer, the apertures in the mesh layer being dimensioned to substantially prevent maggots from passing therethrough. The removable layer is substantially permeable to air and moisture. The removable layer is typically formed of a polyurethane, polyester, cellulose or polyethylene, or a mixture of such materials. It is envisaged however, that biodegradable materials can be used or material that are soluble so that there is the minimisation of non-biodegradable waste. The removable layer or even the entire pouch could also be made of a material that dissolves or disintergrates in contact with wound exudate to provide an automatic release mechanism. By having material that is easy to dispose of, this reduces the cost and risk of contamination of the environment that can occur in connection with disposing of the removable layer. Typical materials that could be used are alginate or a starch based material . The removable membrane is typically adhered to the pouch by an adhesive; the adhesive is preferably non-toxic to maggots which may be contained within the delivery system. Alternatively, the removable layer may be attached by a heating process, with there being areas of weakness in the heat seal that can be broken so the removable layer can be detached from the pouch.

In a further arrangement the maggots could be held inside a second inner bag or pouch, that is separate from the main pouch and which may be ruptured by externally applied forces when the maggot delivery system is to be used.

The pouch would typically have an external dimension typically of 3 to 5cm by 3 to 5cm. However, it is envisaged that the external dimension of the pouch can be varied depending upon the size of the wound to be ultimately treated.

The pouch may include activated charcoal, either included in the material forming the pouch or as a separate entity, for example a disc in a specific area of the pouch. This could be to one edge of the pouch so that there is no affect of movement of the maggots from the pouch to the wound. Activated charcoal has the benefit that where there is necrotic tissue in the vicinity of a wound, odour can be kept to a minimum while the to maggots are breaking down the tissue.

Maggots are living organisms and therefore it is desirable that they are in optimum condition when they are to be used in the maggot delivery system as described.

Therefore according to a further aspect of the present invention, there is provided a maggot delivery transport system which includes a pouch containing a plurality of maggots, the pouch having at least one foraminous portion, the foraminous portion having apertures dimensioned to permit at least one maggot contained in the pouch to pass therethrough, with there being a releasable cover over the foraminous portion to prevent movement out of the maggots from the pouch until the pouch is to be used.

Sometimes, when the maggot delivery system is transported over long distances, and in particular, if the maggots are to be used in tropical climates, it is desirable to maintain the maggots in a dormant state. This may be done by including a cryopreservative, such as trehalose in the bag surroundings. Once the maggots have reached their destination, a source of nutrients can then be delivered to the maggots to regain their activity. The source of nutrients is preferably a sugar based material such as fructose or honey. The nutrients may be introduced either by a port, which allows for injection of the nutrients into the bag. Alternatively, the nutrients can be contained in a blister pack or disc within the bag which can be ruptured by the application of pressure which allows the nutrients to escape into the bag and into proximity with the maggots.

The pouch used with the maggot delivery transport system is substantially as described hereinbefore with reference to the first aspect of the present invention.

According to yet a further aspect of the present invention, there is provided a method of application of maggots to an individual, which method includes: providing a maggot delivery system according to the second aspect of the present invention, applying the maggot delivery system to a desired location on the individual; and securing the maggot delivery system in position on said individual. The method preferably includes attaching separate maggot delivery systems sequentially over a period of time until the wound area is cleaned. The wound will then be able to heal more effectively.

According to yet a further aspect of the invention there is provided a maggot shelter to be used with a maggot delivery system, (or any other maggot delivery arrangement) . The maggot shelter comprises a body having one or more maggot receiving members, the maggot shelter be arranged to be associated with a maggot delivery system that is placeable in proximity to a wound, such that when placed in proximity to the wound, maggots from the maggot delivery system and/or the wound can move into the maggot receiving members as required.

It is envisaged that the maggot receiving members are provided as one or more of pores, channels, apertures or chambers or a combination thereof.

Preferably the pores, apertures chambers, or channels are provided by one or more of the following: an open cell foam, a gauze, a non-woven fabric or a chipped foam. The chipped foam is formed of a plurality of small pieces of foam having air pockets between the pieces, into which maggots can enter. Although open cell foam etc are given as examples of materials that can be used, the examples are not limited to those specific materials mentioned.

The present invention will now be described by way of example only, with reference to the accompanying figure, wherein: Figure 1 represents a plan view of a pouch according to the present invention, prior to use, having the removable membrane in position;

Figure 2 represents a plan view of the pouch shown in figure 1 with the removable membrane removed;

Figure 3 represents a rear plan view of a pouch as shown in Figure 2;

Figure 4 represents a cross-sectional view of the pouch shown in Figure 2 along the line A.a;

Figure 5 represents a maggot rest area, which can be used with the pouch shown in any of figures 1 to 4; and

Figure 6 shows a maggot rest area in the site with a pouch according to the invention.

Referring to the figures, where like numerals have been used to identify like parts, there is provided a maggot pouch 1. The maggot pouch 1 has a protective removable cover member 2 arranged to cover the foraminous layer 4. Removable cover member 2 is provided with a pull tab 3 for ease of removal of the cover member 2 from the pouch.

Foraminous layer 4 has apertures of diameter 600μm which permits maggots 7 to pass therethrough. The foraminous layer 4 is surrounded by an adhesive layer 6 which may be spread around the entire peripheral surface of the foraminous layer. A gas permeable membrane 8 is provided on the rear of the pouch 1 to assist in the longevity of the maggots, and also to prevent their

In use, removable cover 2 is removed from pouch 1 by pulling pull tab 3. Pouch 1 is then applied over the wound to be treated (not shown) and secured in place by adhesive 6. Once pouch 1 is applied to a wound, the maggots 7 are free to exit the pouch 1 and enter the wound (not shown) . The pouch 1 is left in position for the desired time (typically 2 or 3 days) and subsequently removed and disposed of in an appropriate manner.

Figure 5 shows a pouch 1 and a maggot shelter or rest area member 10 which is in the form of a pouch which is smaller that of the main pouch that is applied to a wound. The rest area member has attachment means 9, which may be in the form of an adhesive or velcro by which it can be attached to the inside or outer surface of a pouch 1. The rest area device may have a rupturable area which can be pierced or broken so that maggots can pass from the pouch 1 to the rest area device 10 and back again if desired. Inside the device 9, are channels 11 into which maggots can move and from which they can exit if they move back to the wound area that it in the proximity to the pouch 1.

Figure 6 shows a maggot rest device 10 in site with a pouch 1. In this case, the device is shown as being adhered to the outer surface of the pouch 1.

The present invention covers not only individual embodiments or aspects but also combinations of such embodiments or aspects.

Claims

1. A maggot delivery system including a pouch having at least one foraminous portion, the foraminous portion having one or more apertures to permit one or more maggots to pass when contained in the pouch, from the inside to the outside of the pouch through said foraminous portion.

2. A maggot delivery system according to claim 1, wherein the foraminous portion is a mesh or net type layer having apertures .

3. A maggot delivery system according to claim 1, wherein the foraminous portion is a foam having apertures of sufficient size to permit the passage of maggots

4. A maggot delivery system according to claim 1 or claim 2, wherein each aperture of the foraminous layer is greater than substantially 400μm.

5. A maggot delivery system according to claim 1 or claim 2, wherein each aperture of the foraminous layer is greater that substantially 500μm.

6. A maggot delivery system according to any claims 1 to 3, wherein each aperture of the foraminous layer with a diameter of at least 600μm.

7. A maggot delivery system according to claim 1 or claim 2, wherein the apertures of the foraminous layer are of a range of varying sizes, with some of the apertures ranging from substantially greater than 400μm other apertures being substantially greater than 500μm while other apertures are at least 600μm.

8. A maggot delivery system according to any preceding claim, wherein the foraminous layer is flexible.

9. A maggot delivery system according to any preceding claim including apertures that permits maggots to return to the pouch.

10. A maggot delivery system according to any preceding claim, wherein the pouch includes some apertures that are dimensioned to substantially prevent maggots passing therethrough and returning to the pouch.

11. A maggot delivery system according to any preceding claim, wherein the pouch is a flexible material .

12. A maggot delivery system according to any of claims 1 to 10 wherein the pouch is of substantially inflexible material .

13. A maggot delivery system according to any preceding claim, wherein the pouch formed of one or more of a nylon, polyethylene, polypropelene or a polyester material .

14. A maggot delivery system according to any preceding claim, wherein the pouch has at least one gas permeable area, to increase longevity of maggots contained in the pouch. 15. A maggot delivery system according to any preceding claim, including a removable layer arranged to cover the foraminous portion.

16. A maggot delivery system according to claim 15, wherein the removable layer is selected from one of a semi-permeable layer or a mesh layer, the semi-permeable or mesh layer having apertures that prevent maggots passing through the removable layer.

17. A maggot delivery system according to claim 16, wherein the removable layer is substantially permeable to air and moisture.

18. A maggot delivery system according to and claims 15, 16 or 17 wherein the removable layer is attached to the pouch by a releasable adhesive.

19. A maggot delivery system according to claim 18, wherein the removable layer has a pull tab, allowing for removal of the removable layer.

20. A maggot delivery system according to any preceding wherein the maggots are contained in a separate inner pouch which may be ruptured to permit release of the maggots into the pouch.

21. A maggot delivery system according to any preceding claim, wherein the pouch includes a maggot shelter provided with a series of channels or apertures in which maggots can return to the pouch.

22. A maggot delivery system according to claim 21, wherein the shelter is provided by one or more of the following, an open cell foam, gauze, non-woven fabric, chipped foam.

23. A maggot delivery system according to any preceding claim including odour reducing materials .

24. A maggot delivery system according to claim23, wherein the odour reducing material is an activated charcoal .

25. A maggot delivery system according to claim 2 or claim 24 wherein the odour reducing material is provided either as an insert in the pouch or is provided as part of the material forming the pouch.

26. A maggot delivery transport system, formed of a pouch containing a plurality of maggots, the pouch having at least one foraminous portion with one or more apertures to permit one or more maggots contained in the pouch to pass there through, the foraminous portion having a cover, which prevents maggots exiting from the pouch until the cover is removed.

27. A maggot delivery transport system according to claim 26, including features according to any of the claims 2 to 25.

28. A maggot delivery transport system according to either of claims 26 or 27 including a composition to maintain the maggots in a dormant state.

29. A maggot delivery transport system according to claim 28, wherein the composition is a cryopreservative. 30. A maggot delivery transport system according to claim 29, wherein the cryopreservative is trehalose.

31. A maggot delivery transport system according to any of claims 26 to 30 including a nutrient source for the maggots.

32. A dressing or bandage including a maggot delivery system according to any of claims 1 to 25 or a maggot delivery transport system according to any of claims 26 to 31.

33. A maggot delivery system according to any of claims 1 to 25, a maggot delivery transport system according to any of 26 to 32 or a bandage or dressing according to claim 32 formed of a biodegradable material.

34. A maggot delivery system, a maggot delivery transport system or a dressing according to claim 33 wherein the biodegradable material is selected from one or more of a gelatine, a cellulose, and alginate or a starch based material .

35. A method of application of maggots to the body, the method including positioning and securing a pouch containing a plurality of maggots against a wound on the body, leaving the pouch in proximity to the wound allowing the maggots contained in said pouch to migrate from the pouch to the wound, leaving the pouch in position for a period of time, removing the pouch from the wound after a period of time.

36. A method according to claim 35, wherein one or more further pouches are sequently placed on the body and then removed therefrom until treatment is terminated.

37. A method according to claim 36, wherein each pouch is left in position for up to three days, is removed and then a further pouch is positioned and secured, this process continuing until treatment is terminated.

38. A maggot shelter to be used with a maggot delivery system, the maggot shelter comprising a body having one or more maggot receiving areas, the maggot shelter being arranged to be associated with a maggot delivery system that is placeable in proximity to a wound, , such that when the delivery system is placed in proximity to a wound, maggots from the maggot delivery system and/or the wound can move into the maggot receiving areas.

39. A maggot shelter according to claim 38, that is insertable within a pouch of a maggot delivery system.

40. A maggot shelter according to claim 38, that includes attachment means to attach the maggot shelter to a pouch of a maggot delivery system.

41. A maggot shelter according to claim 40, wherein the attachment means is a releasable adhesive.

42. A maggot shelter according to any of claims to 41 wherein the maggot receiving areas comprise one or more of apertures, pores, channels or spaces into which maggots can enter.

42. A maggot shelter according to claim 42, wherein the maggot receiving areas are formed of one or more of an open cell foam, a gauze, a non-woven fabric or chipped foam.

44. A maggot shelter according to any of claims 38 to 42, including a rupturable area which can be ruptured providing access for the maggot into the maggot shelter.