''Cordylobia rodhaini'', also known as the Lund's fly, derived its common name from captain Lund, who was the first European to show symptoms of the disease caused by the larvae of the same fly. Lund's fly belongs to the genus ''

Cordylobia ''Cordylobia'' is a genus of flies from the family Calliphoridae. The larvae of ''Cordylobia'' are parasitic on mammals, especially rodents. Two species, '' C. anthropophaga'' (the tumbu fly) and '' C. rodhaini'' (Lund's fly), also are known as pa ...

'', flies from the family

Calliphoridae The Calliphoridae (commonly known as blowflies, blow flies, blow-flies, carrion flies, bluebottles, or greenbottles) are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing bait, ...

. The larvae of the Lund's fly are parasites of thinned-skinned mammals, especially the Gambian rat, mona monkey and small antelopes and are only accidental parasites of humans. The adult flies feeds on rotting fruits, vegetables and animal feces, and are most abundant in the wet season. Like many tropical insects they are most active in the dark periods and have the greatest activity early in the morning and late in the evening while resting typically between 8am to 5pm. The Lund's fly are largely confined to

tropical Africa The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...

, especially the rainforest areas in

Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...

. As a result of human migration, though, the parasitic infections they cause have been recorded in other continents, including Europe and Asia.

Life cycle

The life cycle of Lund's fly typically lasts from 55 to 67 days. The female fly lays up to 500 eggs and deposits her eggs on dry sand polluted with the excrement of animals, or can also lay them on human clothing. In about three days, the larva attached to its host, is then activated by the warm body of the host. The larva then hatches and breaks through the skin. A maturing larva induces a painful swelling. In about 12 to 15 days, the larva reaches a length of about 23 mm, exits the skin of the host, and falls to the ground to pupate. The adult fly emerges in 23 to 26 days, and the life cycle continues.

Larval structure

Lund's fly is parasitic at its larval stage. Under examination with a

scanning electron microscope A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that ...

, it appears whitish and barrel-shaped, with 11 segments. Its body is almost completely covered by large cone-shaped spines. These spines serve as a point of attachment to its host. The larvae have a brown apex, pointing towards the posterior end where fewer spines occur. Two bulges exist in the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

end with paired mouth hooks at the anterior end of the larvae. After hatching, the larvae penetrate into the

dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...

and molt to second- and third-instar larvae before emerging from the skin. The third-instar larvae have an approximate length of 1.5 cm and are distinctively less elongated and

conical In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the ''apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines, ...

in shape, compared to the second-instar larvae.

Lund's fly-induced myiasis

Myiasis Myiasis ( ), also known as flystrike or fly strike, is the parasitic infestation of the body of a live animal by fly larvae (maggots) that grow inside the host while feeding on its Biological tissue, tissue. Although flies are most commonly attr ...

is generally defined as the infestation of animal tissue by the larvae of some flies. The larvae of myiasis-causing flies feed on animal tissue and/or bodily fluids. Myiasis caused by Lund's fly larvae have been reported in

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

, Congo,

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

, and

Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...

. It is very similar to the myiasis that caused by the tumbu fly, the latter co-existing in the same geographical regions as Lund's fly. Clinical symptoms start with the formation of a red

papule A papule is a small, well-defined bump in the skin lesion, skin. It may have a rounded, pointed or flat top, and may have a umbilication, dip. It can appear with a Peduncle (anatomy), stalk, be thread-like or look warty. It can be soft or firm a ...

, which is characterized by a small raised swollen area of the skin. These can form on any area of the skin, with the arms, legs, arms, and back most frequently affected. Patients typically do not report pain at this stage of infection. The

enlarges with time, penetrates deep into the skin, and develops a central opening, now classified as a

furuncle A boil, also called a furuncle, is a deep folliculitis, which is an infection of the hair follicle. It is most commonly caused by infection by the bacterium ''Staphylococcus aureus'', resulting in a painful swollen area on the skin caused by a ...

. The central opening facilitates gaseous exchange for the larva while a

serous fluid In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fl ...

also exits the same opening. The central opening also makes it possible for the larva to excrete its fecal matter. At this point, itching and burning sensation are usually described by patients in the affected areas of the skin. Patients also report symptoms such as

insomnia Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low ene ...

(due to pains at night) and fatigue. The disease is usually self-limiting as the larva drops out, upon reaching the third-instar larval stage. Also, Lund's fly larvae infestation in systemic areas, such as the internal organs, or blood vessels, has not been reported. The most serious incident of Lund's fly-induced myiasis reported so far resulted in swelling of the

lymph nodes A lymph node, or lymph gland, is a kidney-shaped Organ (anatomy), organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphoc ...

due to adverse immune reactions in the patient. A major distinction between myiasis caused by Lund's fly and that caused by other flies is that lesions in Lund's fly myiasis are usually smaller and multiple. Myiasis caused by tumbu fly is, though, similar to that caused by Lund's fly; the two flies belong to the same genus and share similar characteristics.

Treatment

As the larvae fall off eventually, the disease is self-limiting and no treatment is usually needed, but to facilitate healing, the larvae can be physically removed from the infected region. This is done by applying gentle manual pressure to any two ends of the

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

until the larvae come out Occasionally,

petroleum jelly Petroleum jelly, petrolatum (), white petrolatum, soft paraffin, or multi-hydrocarbon, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons (with carbon numbers mainly higher than 25), originally promoted as a topical ointment for i ...

or oil is applied to the opening in the lesion, to reduce oxygen supply to the larvae, thereby forcing them to move closer to the surface. Improper removal of the larvae could lead to inflammation of the

as bursting of the fluid from the larvae could lead to

allergic reactions Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...

in some people. Proper covering of the wound prevents further infection. Unsterilized objects should not be used to open lesions, as this could result in infection.

Hyperpigmentation Hyperpigmentation, also known as the dark spots or circles on the skin, is the darkening of an area of Human skin, skin or nail (anatomy), nails caused by increased melanin. Causes Hyperpigmentation can be caused by sun damage, inflammation, or ...

may persist on the skin of the infected area months after infection. Also, lack of experience in diagnosing Lund's fly-induced myiasis could lead to a misdiagnosis of

impetigo Impetigo is a contagious bacterial infection that involves the superficial skin. The most common presentation is yellowish crusts on the face, arms, or legs. Less commonly there may be large blisters which affect the groin or armpits. The les ...

, insect bites,

folliculitis Folliculitis is the infection and inflammation of one or more hair follicles. The condition may occur anywhere on hair-covered skin. The rash may appear as pimples that come to white tips on the face, chest, back, arms, legs, buttocks, or head. A ...

, or other skin disorders.

Prevention and control

Generally, humans are accidental hosts of myiasis as a result of Lund's fly larvae infestation, so are less likely to be infected. Infestation can pose a health problem, though, for the local population in the endemic region and tourists alike. Infestations of Lund's fly larvae are usually diagnosed in tourists and foreign workers who previously travelled to the endemic regions. Therefore, incidence rates might be under-reported in endemic regions, and might be treated by local means. Even as it can be spread by human travel, it has not reported to be contagious and is also less likely to thrive in regions other than sub-Saharan Africa, due to differences in climate. As eggs are usually laid on wet clothing in endemic regions, clothes should not be left outside for long periods, specifically at

dawn Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the diffuse sky radiation, appearance of indirect sunlight being Rayleigh scattering, scattered in Earth's atmosphere, when the centre of the Sun's disc ha ...

twilight Twilight is daylight illumination produced by diffuse sky radiation when the Sun is below the horizon as sunlight from the upper atmosphere is scattered in a way that illuminates both the Earth's lower atmosphere and also the Earth's surf ...

, as this is when Lund's flies are most active and likely to lay eggs. Also, ironing all clothes to kill eggs or larvae can help to reduce the incidence of myiasis. Good hygiene can also play a role in preventing myiasis, as Lund's flies are known to feed in dirty surroundings and lay eggs where they breed.

References

{{Taxonbar, from=Q14538324 Calliphoridae Parasitic flies Diptera of Africa Insects described in 1910