Aerosinusitis or Barosinusitis

This is painful inflammation or edema of the sinuses (especially the frontal sinuses), which may be accompanied by bleeding and preceded by an upper respiratory tract infection or acute exacerbation of allergies. It occurs when flying in an aircraft or during deep sea diving and is due to non-equilibration or pressure differences of the internal (within the sinuses) and  the external atmospheric pressure.
It can also be called Barotrauma or Sinus squeeze

Paranasal Sinusis (Picture Credit ;Central Coast ENT)

It occurs about 3-4 episodes per 100,000 exposures, has no racial or gender predilection & rarely reported in children, as the frontal sinuses are not fully developed.

Risk Factors

• Upper respiratory tract infection
• Allergy
• Ambient pressure changes or rapid altitude changes; High altitude flyers, high-performance aircraft, military pilots, Deep-sea Divers, Sport divers, Caisson or tunnel workers.
• Nasal polyps
• Anatomic abnormalities of the nose
• Smoking; in children and older adults
• Flying in an airplane after diving

Pathophysiology

Normally,for ventilation and mucocilliary clearance to occur, the sinuses drain through a small ostia into the nasal cavity. This leads to an equilibrium in pressure between the sinuses and the external atmosphere. But when this opening/ostia is blocked by mucousal thickening (as seen in allergies, upper respiratory tract infection, nasal polyps etc) there is no free flow of air (or equilibrium) between the sinuses and the nasal cavity. Following a rapid change in altitude (during flight or diving), there may be compression on the fifth cranial nerve, thus resulting in the Severe frontal headache which is experienced during Aerosinusitis.

There are 2 types of acute barotrauma: The Squeeze and The Reverse Squeeze.
Squeeze occurs during descent; when the sinuses contracts producing a negative pressure, air is trapped causing a partial vacuum within the sinus cavities. If the vacuum is great enough, it causes rupture of the blood vessels in the sinus cavities and may tear the membrane lining. The pain involved is usually sharp, piercing, and severe; upon descent the sinuses may fill with fluids/transudates, and there may be nose bleeding.

The Reverse squeeze occurs during ascent, when the sinuses expand and the pressure increases within the sinuses, but the air within the sinuses cannot escape to the nasal cavity because the ostia is blocked. The expanded sinuses compresses on the fifth cranial nerve, producing frontal headache.

This pathophysiology can be explained by Boyle's law, which states that "the volume of a gas is inversely proportional to the pressure on it, when temperature is constant (V = CT/P)".


Grades
Weissman grading of aerosinusitis;
    Grade I; mild transient sinus discomfort without visible features on X-ray.
    Grade II; pain lasting up to 24 hrs, with some mucosal thickening on X-ray, Serosanguinous Rhinorrhea.
    Grade III; Severe pain lasting more than 24 hrs with X-ray film showing severe mucosal thickening or opacification of the affected sinus; subsequent sinusitis may be observed. Epistaxis, Hematoma and mucosal avulsion.

Signs and symptoms
The predominant symptom is sudden & sharp facial pain or headache during ascent or descent
Mild
 mild pain just above the brow, rarely referred to other regions of the head
 rarely or occassionally have nose bleeding (epistaxis)
Severe
Sudden, sharp and severe pain in the face,and refered to other regions of the head (retroorbital, midface etc).
Accompanied by Nose bleeding (Epistaxis)

Diagnosis
This is Clinical; positive history of the risk factors and symptoms following exposure.
Radiological examination is not really necessary for the diagnosis as this can be done from the history and physical examination. However it may be useful for grading of the Barotrauma.

X-Ray shows mucosal thickening.
CT scanning shows the sinuses involved, extent of any hematoma, and mucosal thickening. It can also suggest the predisposing factor.

Differential Diagnosis
Nasal Polyposis
Turbinate Dysfunction
Seasonal or perineal allergic rhinitis
Nasal septal deviation
Concha bullosa

Prevention
Use a nasal decongestant before ascending or descending,
Avoid rapid descent or ascent,
Avoiding airplanes or scuba diving when you have an upper respiratory infection,
Use valsalva maneuvers to help equalize pressure in the sinuses and inner ears,
Chew gum during take off or landing,
Yawn during flight,
Use filtered earplugs,
Be properly trained before diving.
To prevent pulmonary barotrauma, do not hold your breath during ascent (divers).
Don’t smoke before diving.
Don’t stay under the water at greater depths for so long.
Avoid flying or going to a higher altitude within 24 hours after diving.

Treatment
Most often, immediate treatment is not always possible, but ideally the following should be done;
Immediately return to the altitude which the symptom started (this may be difficult if it happens in a commercial flight) apply topical nasal decongestants before ascending/descending slowly.
Treatment should be aimed at; pain control, ventilation and to prevent infection.
Pain control with analgesics. Depending on the severity, nacortics can be prescribed. Avoid NSAIDs as it may worsen the Hematoma
Ventilation can be aided with nasal decongestants; oral or nasal spray,
Prevent secondary infections using broad spectrum antibiotics (e.g cephalosporins) because the accumulated transudates, hematoma and damaged mucosa can serve as a medium for bacterial growth.
Surgery can be done for very severe cases lasting more than 24hrs and when the analgesics fail to relieve pain. The following surgeries can be performed; Septoplasty, turbinectomy,balloon sinuplasty, Endoscopic sinus surgery etc.


Complications
 Long-term or permanent hearing loss,
 Ear infection,
 Perforated eardrum.
 Orbital cellulitis,
 Meningitis,
 Brain abscess,
 Osteomyelitis (Pott's puffy tumour when the frontal bone is affected)
 Cavernous sinus thrombosis.

Paranasal Sinusis (picture Credit; Pediatrics ENT Associates)

Notes
1) American Academy of Otolaryngology—Head and Neck Surgery; Barosinusitis

2) Brubakk, A. O.; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN 0-7020-2571-2

3) Encyclopedia Britannica; Aerosinusitis

4) Fitzpatrick DT, Franck BA, Mason KT, Shannon SG (1999). "Risk factors for symptomatic otic and sinus barotrauma in a multiplace hyperbaric chamber". Undersea Hyperb Med 26 (4): 243–7. PMID 10642071.

5) Gunn DJ, O'Hagan S. Unilateral optic neuropathy from possible sphenoidal sinus barotrauma after recreational scuba diving: a case report. Undersea Hyperb Med. Jan-Feb 2013;40(1):81-6.

6) Hanna HH, Tarington CT. Otolaryngology in aerospace medicine. In: DeHart RL, ed. Fundamentals of Aerospace Medicine. Philadelphia: Lippincott Williams & Wilkins; 1985:520-530.

7) Kristin Hayes, Preventing Sinus Squeeze, Ent About. Updated October 30, 2014.

8) Medical Dictionary; Segen's Medical Dictionary. © 2012 Farlex,

9) Medscape; Aerosinusitis

10) US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006.

11) Wikipedia; Aerosinusitis

Harlequin ichthyosis or Harlequin baby

A rare autosomal recessive disease of infants in which the baby is encased in a massive, horny shell of dense, plate-like scale (hyperkeratotic ‘cocoon’) with deep cracks (fissures), accompanied by contraction abnormalities of the eyes (ectropion), turning outwards of a lip (eclabium), and flattened ears.
Also known as; Harlequin-type ichthyosis, keratosis diffusa fetalis, Harlequin fetus

It is the most severe form of autosomal recessive congenital ichthyosis where the dermis to be around 10 times thicker than normal.

Harlequin Baby ( Picture credit; Parakovacs )

It was first Described in 1750 by Rev. Oliver Hart, a cleric from South Carolina. The term "harlequin" derives from the newborn's facial expression, the triangular and diamond-shaped pattern of hyperkeratosis.

It has an incidence rate of less than 1/1,000,000. It has no racial predilection and affects male and female equally.

Risk Factors

• Family History of Ichthyosis or other Severe Skin disorders
• Consanguineous Couples; Marrying a blood relation
• Having another child with ichthyosis ( 25% risk of recurrence)

Pathophysiology

In Harlequin ichthyosis there is Mutations of ABCA12; The gene which is responsible for fat(lipids) transport from lamellar granules to the apical surface of granular layer keratinocytes (spaces between the cells in the skin’s uppermost layer). Thus this mechanism becomes defective resulting in a severe dyskeratosis, caused by defective lipid metabolism; as the lipids are not transported, the stratum corneum is up to 30-fold thicker than the stratum malpighii & the stratum granulosa is decreased to a one-cell layer or absent.

Signs & Symptoms
History of previous intrauterine or neonatal death,
Decreased fetal movements or intrauterine growth retardation noted during the pregnancy,
Preterm delivery,
Bleeding at birth,
Severely thickened & hyperkeratotic skin which is scale-like and shiny with deep cracks/fissures.
Everted eyelids (Ectropion) with dryness of the cornea
The Nose and Ears may be poorly formed or absent
The Lips are retracted (Eclabium)
Sparse hair distribution, alopecias
Poor movement in the joints & contractures
Failure to thrive
Dehydration as a result of fluid loss from the cracked skin.
Hyperthermia due to thickened skin and absence of sweating
Respiratory distress and respiratory failure following poor chest wall expansion

Diagnosis
This is purely clinical, the risk factors, signs and symptoms should be noted.
Prenatal diagnosis, using amniotic fluid sample at 17weeks of gestation, especially for fetuses with positive family history
Prenatal 2D or 3D ultrasonography shows; a large and gaping mouth, aplasia of the nose, abnormal limbs, and bulging eyes; all features of Harlequin ichthyosis.
Genetic testing for mutations in the ABCA12 gene
Full Blood Count; may show decreased heamoglobin, increase White blood cells
Blood culture for infections
Serum Electrolytes Urea and Creatinine may be abnormal due to dehydration.
Chest X-Ray in respiratory distress.
Skin Biopsy for histological studies.

Differential Diagnosis

Self-healing lamellar ichthyosis of the newborn.
Congenital ichthyosiform erythroderma.
Collodion baby.
Lethal restrictive dermopathy.
Infantile systemic hyalinosis.
Neu-Laxova syndrome.

Treatment
The management of Harlequin Ichthyosis is multidisciplinary as well as supportive. It involves the; Neonatologist, Ophthalmologist, Dermatologist, Dietician, Plastic Surgeon, Psychologists etc.
Intravenous access may be difficult here, thus umbilical cannulation is recommended.
Supportive measures include; 

• Monitoring the patient in a Neonatal Intensive care unit,
• The use of Humidified incubator (to maintain body temperature and to prevent the skin from cracking).
• Rehydration
• Lubricating the Cornea with Ophthalmic lubricants
• Emollients can be applied liberally to the skin
• Antibiotics to help prevent infection & sepsis
• Retinoids; Oral(Isotretinoin or acitretin) and Topical Retinoids (Tazarotene) to accelerate shedding of the skin scales.

Complications
Impaired vision
Delayed developmental milestones
Fulminant Sepsis
Failure to thrive
Respiratory failure
Renal failure

Prognosis
The mortality rate for harlequin ichthyosis is high, close to 50%. However, following the discovery of Isotretinoids the prognosis is improving.
Presently, the Oldest surviving person with Harlequin ichthyosis is Nusrit "Nelly" Shaheen, 30years old, from West Midlands in Britain. She was born in 1984,

Harlequin Ichthyosis (Picture Credit; ObGyn)

NOTES

1) Akiyama M. ABCA12 mutations and autosomal recessive congenital ichthyosis: a review of genotype/phenotype correlations and of pathogenetic concepts. Hum Mutat. Oct 2010;31(10):1090-6.

2) Chua CN, Ainsworth J. Ocular management of harlequin syndrome. Arch Ophthalmol. Mar 2001;119(3):454-5

3) First foundation for Ichthyosis and related skin types | Harlequin Ichthyosis

4) Ichthyosis Support Group | harlequin-ichthyosis

5) Kelsell DP, Norgett EE, Unsworth H, et al. Mutations in ABCA12 underlie the severe congenital skin disease harlequin ichthyosis. Am J Hum Genet. May 2005;76(5):794-803

6) Koochek A, Choate KA, Milstone LM. Harlequin Ichthyosis: Neonatal Management and Identification of a New ABCA12 Mutation. Pediatr Dermatol. Mar 2014;31(2):e63-4.

7) Lefevre C, Audebert S, Jobard F, et al. Mutations in the transporter ABCA12 are associated with lamellar ichthyosis type 2. Hum Mol Genet. Sep 15 2003;12(18):2369-78.

8) Medscape; Harlequin Ichthyosis

9) Liu RH, Becker B, Gunkel J, Teng J. Rapid improvement in digital ischemia and acral contracture in a collodion baby treated with topical tazarotene. J Drugs Dermatol. Jun 2010;9(6):713-6.

10) Orphanet; ORPHA457, Harlequin ichthyosis

11) Rajpopat S, Moss C, Mellerio J, et al. Harlequin ichthyosis: a review of clinical and molecular findings in 45 cases. Arch Dermatol. Jun 2011;147(6):681-6.

12) Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0

13) Wikipedia; Harlequin Ichthyosis

Maggot Therapy

Also called; Biodebridement, Maggot debridement therapy (MDT) or Larval therapy.

This is the controlled, therapeutic application of live blowfly (Lucilia sp) larvae ("maggots") into non-healing wounds to to aid in wound debridement (cleaning), disinfection and/or healing.It can also be termed "Therapeutic Myiasis" as we recall that maggot infestation on a living vertebrate host is called "myiasis".

Maggot Therapy (Picture Credit; Science Open)

"Despite our low cultural esteem for maggots, more and more clinicians and patients are turning to medicinal maggots for assistance with their wound healing. For most, the drawbacks of maggot therapy pale in comparison to the remarkable efficacy in treating even the most recalcitrant wounds"- Ronald A. Sherman,

Though It sounds medieval, Maggot therapy is an accepted part of modern medicine as Debridement is an essential component of wound care; the presence of devitalized tissue can impede the healing process.

History Of Maggot Therapy
The beneficial effects of therapeutic myiasis were first observed during the Napoleonic war by Larrey, who noted that soldiers whose wounds had become infested with maggots had an improved prognosis.
William Baer, while at Johns Hopkins University in Baltimore, Maryland, may have been the first person to have intentionally applied larvae to wounds in order to induce wound healing. During the late 1920's, he identified certain species, raised them in the laboratory, and used their larvae to treat several children with osteomyelitis and soft tissue infections. He presented his findings at a surgical conference in 1929. Two years later, after treating 98 children, his findings were published posthumously.
Throughout the 1930’s Maggot Therapy was performed routinely by Doctors until the discovery of new antibiotics and surgical techniques that came out during World War II. Maggot therapy was occasionally used during the 1970's and 1980's, but only when antibiotics, surgery, and modern wound care failed to control the advancing wound.

The emergence of antibiotic-resistant strains of bacteria such as methicillin resistant Staphylococcus aureus (MRSA) and the curiosity of researchers prompted the reemergence of larval therapy during 1970's & 1980's . As a treatment it meets the demands of clinical governance, being not only beneficial to the patient, but also being proven to be more cost-effective.

In January 2004, the U.S. Food and Drug Administration (FDA) granted permission to produce and market Medicinal maggots. Same year the British National Health Service (NHS) gave approval for maggot therapy. Presently, about 30 countries around the world are using Maggot therapy; In Africa, it is being used in Kenya & South Africa. In European Union, Canada, Japan, maggots are classified as medicinal drugs, needing a full market license.

Mechanism Of Action
Debridement; The maggots secrete a broad spectrum of digestive juice (collagenases, proteolytic enzymes, serine proteases) that selectively liquefy and absorb only necrotic tissue (extracorporeal digestion). Also Mechanical Debridement by the specific mandibles or “mouth hooks” of the maggots and their rough body which both scratch the necrotic tissue.

Disinfection; It was discovered that secretions from maggots (allantoin, urea, phenylacetic acid, phenylacetaldehyde, calcium carbonate, proteolytic enzymes, etc) have broad-spectrum antimicrobial activity, and microbes not killed by these secretions are subsequently ingested and lysed within the maggots. Maggot secretions have been found to dissolve biofilms.

Stimulation of healing; The alkalinity of maggot-treated wounds, along with the isolated allantoin and urea-containing compounds is responsible for wound healing. In fact, today, allantoin and urea are components of many cosmetics. Maggot secretions also;
 -stimulates the proliferation of fibroblasts and endothelial tissue ,
 -increases angiogenesis,
 -enhances fibroblast migration over model wound surfaces.
Using remittance spectroscopy to evaluate patients before and after maggot therapy, Wollina and colleagues found that vascular perfusion and tissue oxygenation surrounding the wound actually increased following maggot therapy. Zhang and colleagues are currently seeing evidence that maggot extracts may even stimulate the growth of neural tissue.

Uses/Indication

• Diabetic Foot Ulcer
• For debriding non-healing necrotic skin and soft tissue wounds including;

               -pressure ulcers,
               -venous stasis ulcers,
               -neuropathic foot ulcers,
               -non-healing traumatic or post-surgical wounds
               -infectious

• In diabetic and non-diabetic subjects for wound bed preparation prior to surgical closure.

Dosage & Administration
Maggots are applied to the wound at a dose of 5–10 larvae per square centimeter of wound surface area and are left within their dressing for 48–72 hrs. At that point they are satiated (as evidenced by increase in size), finished working, and can be removed and safely disposed.

Maggot therapy being a controlled therapeutic myiasis (maggot infestation on a live host) is controlled by;

selecting a safe and effective species and strain,

• chemical disinfection to make the maggots germ-free (sterile maggots),
• containing the maggots within special dressings(e.g maggot confinement dressings; Le Flap™,Biobag™ ) that prevent them from leaving the wound unescorted,
• quality control measures throughout the breeding and production processes.

Not all species are safe and effective. The maggots cleared for marketing in the United States belong to the (currently named) LB-01 strain of Phaenicia (Lucilia) sericata.

Advantages Of Maggot Therapy

1. Takes about 15-30 minutes to apply a secure dressing to keep the maggots in place
2. Low cost of treatment
3. Excellent safety record.
4. Simple enough that non-surgeons can use it to provide thorough debridement when surgery is not available or is not the optimal choice
5. Provide surgical quality debridement as an outpatient or in the home
6. Provides treatment for wounds infected by strains of methicillin resistant Staphylococcus aureus (MRSA)
7. As larvae are typically applied for 3 days, wounds are disturbed less frequently than conventional dressings that require changing everyday

Disadvantages

1. Bacteria like Pseudomonas aeruginosa, Escherichia coli, Enterococcus, Proteus are not attacked by maggots and in case of Pseudomonas even the maggots are in danger. Consequently, using maggots alone might lead to a change of bacteria cultures on the wound.
2. Ineffective in case of highly discharging or dried wounds
3. Medicinal maggots are highly perishable and susceptible to transportation problems and delays. Young, starving larvae require food, water, and oxygen, and they are temperature sensitive. Therefore they must be shipped by overnight courier, and their arrival should be timed no more than 24 h before their application to the wound. Delivery delays and exposure to extreme temperatures decrease their survival.
4. Occasionally the maggots may escape from the wounds and 1–2 weeks later become adult flies (“used maggots” and flies are essentially mobile fomites)
5. Local discomfort, itching, unaesthetic appearance to the patient along with cost of the therapy and short half life of maggots
6. It cannot be used in open wounds of body cavities as the environment is not suitable
7. Negative perception with which it is regarded by both patients and doctors; The 'yuk factor'

Side Effects
Minor bleeding,Pain,
Excessively induced exudates,
Increased body temperature,
Flu-like symptoms,
Allergic reaction,
Skin maceration
Discomfort.

Contraindications
Patients refusal.

Alternative Therapies

• Biotherapies like; apitherapy (application of honey) and application of leeches.
• Sonotherapy (with use of ultrasounds)
• Hydrosurgical therapy (with use of water jets)
• Hyperbaric Oxygen Therapy (HBOT)

Medical Maggots™ (Picture Credit; Live science)

Maggot Debridement Therapy (Picture Credit; btmcl)

NOTES
1) A. J. Horobin, K. M. Shakesheff, S. Woodrow, C. Robinson, and D. I. Pritchard, “Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon interactions between human dermal fibroblasts and extracellular matrix components,” The British Journal of Dermatology, vol. 148, no. 5, pp. 422–933, 2003.

2) A. G. Smith, R. A. Powis, D. I. Pritchard, and S. T. Britland, “Greenbottle (Lucilia sericata) larval secretions delivered from a prototype hydrogel wound dressing accelerate the closure of model wounds,” Biotechnology Progress, vol. 22, no. 6, pp. 1690–1696, 2006.

3) Dariusz Waniczek, Andrzej Kozowicz, Małgorzata Muc-Wierzgoń, Teresa Kokot, Elżbieta Świętochowska, and Ewa Nowakowska-Zajdel, "Adjunct Methods of the Standard Diabetic Foot Ulceration Therapy,"  Evidence-Based Complementary and Alternative Medicine
Volume 2013 (2013), Article ID 243568 Chapter 3

4) P. E. Prete, “Growth effects of Phaenicia sericata larval extracts on fibroblasts: mechanism for wound healing by maggot therapy,” Life Sciences, vol. 60, no. 8, pp. 505–510, 1997.

5) R. A. Sherman, "Mechanisms of Maggot-Induced Wound Healing: What Do We Know, and Where Do We Go from Here?" Evidence-Based Complementary and Alternative Medicine
Volume 2014 (2014), Article ID 592419

6) R. A. Sherman, “Maggot therapy for foot and leg wounds,” International Journal of Lower Extremity Wounds, vol. 1, no. 2, pp. 135–142, 2002.

7) R. A. Sherman, "Maggot Therapy takes us back to the future of wound care: New and Improved Maggot Therapy for 21st Century" J Diabetes Sci Technol. 2009 Mar; 3(2): 336–344.

8) U. Wollina, K. Liebold, W. Schmidt, M. Hartmann, and D. Fassler, “Biosurgery supports granulation and debridement in chronic wounds—clinical data and remittance spectroscopy measurement,” International Journal of Dermatology, vol. 41, no. 10, pp. 635–639, 2002.

9) Wikipedia, "Maggot Therapy"

10) W. Robinson, “Stimulation of healing in non-healing wounds by allantoin occurring in maggot secretions and of wide biological distribution,” Journal of Bone and Joint Surgery, vol. 17, pp. 267–271, 1935

11) Z. Zhang, S. Wang, Y. Diao, J. Zhang, and D. Lv, “Fatty acid extracts from Lucilia sericata larvae promote murine cutaneous wound healing by angiogenic activity,” Lipids in Health and Disease, vol. 9, article 24, 2010.

12) Z. Zhang, S. Wang, X. Tian, Z. Zhao, J. Zhang, and D. Lv, “A new effective scaffold to facilitate peripheral nerve regeneration: chitosan tube coated with maggot homogenate product,” Medical Hypotheses, vol. 74, no. 1, pp. 12–14, 2010.

Myiasis

 Infestation of a live Vertebrate (human or animal)  by the larvae of flies, characterized as cutaneous (subdermal tissue), gastrointestinal, nasopharyngeal, ocular or urinary symptoms depending on the region invaded. Often caused by two-winged (dipterous) flies.

Oral Myiasis

This condition was first observed by Ambroise Paré, the chief surgeon to King Charles IX and King Henry III, who said that maggots often infested open wounds, but the term "Myiasis" was coined by Reverend Frederick William Hope in 1840 to refer to diseases resulting from dipterous larvae which differs from those caused by other insect larvae(scholechiasis).

The name Myiasis comes from the Greek word "myia" which means "fly"

Epidemiological data on human myiasis are scant as registration of cases is not usually obligatory
Myiasis is not prevalent in any particular race & has no sex or age predilection.

Risk Factors.
The following risk factors for developing myiasis;
Traveling to endemic areas.
Tropical and subtropical countries (climatic conditions)
Children are particularly prone to the infestation ( thinner skin and lesser immunity),
elderly, psychiatric patients, alcoholics, and other helpless patients,
homeless,
Poor hygiene,
Poor socioeconomic circumstances,
presence of an open wound (preexisting suppurative lesions)
population Hits, (e.g sitting or lying on the ground and some religious rites).
Dermatologic Conditions (e.g Neuropathic ulcers,cutaneous B lymphoma, leprosy etc.)

Pathophysiology

Dermatobia hominis/human bot fly (South and Central America);  the female egg-bearing Bot fly catches a blood-sucking arthropod (e.g a mosquito), and attaches her eggs to its abdomen (means of transportation known as phoresy). When the mosquito takes a blood meal from human, the local heat induces the eggs to hatch and drop to the skin of the host and enter painlessly through the bite of the carrier or some other small trauma.This gives rise to  Furuncular myiasis.

Cordylobia anthropophaga/tumbu fly (Sub-Saharan Africa); The Tumbu fly is attracted by the odor of urine and feces. The females lay their eggs on dry, sandy soil or on damp clothing hung out to dry. The eggs hatch in 1-3 days and can survive near the soil surface or on clothes for up to 15 days waiting for contact with a suitable host. Activated by heat, such as the body heat of the potential host, they are capable of penetrating the unbroken skin with sharp mandibles resulting in  Furuncular myiasis.

Cochliomyia hominivorax/blow fly (South and Central America) The adult Female Blow flies deposit the eggs near poorly managed wounds and the larvae feed on necrotic tissue resulting in Wound Myiasis. Flies may be dispersed by prevailing winds, and infection is often acquired while resting outside during the day or may result from trauma.

Cuterebra sp (North America)
Wohlfahrtia sp (Europe, North America, and Pakistan)

Signs & Symptoms

• History of an insect bite which precedes the lesion
• In human beings, the most common site is the eye
• severe eye irritation, pain, redness,swelling of the eyelids, foreign body sensation & lacrimation are common symptoms of patients with ophthalmomyiasis.
• epistaxis, foul smell, passage of worms, facial pain, nasal obstruction, nasal discharge, headache, dysphagia, and sensation of foreign body in the nose can be seen in Nasal Myiasis.
• Myiasis is very painful, with sudden paroxysmal episodes of lancinating pain
• intense itching (Pruritus)
• at first, It looks like an ordinary large boil,often ooze (serosanguineous drainage or purulent fluid),
• a small aperture is seen covered by a crust at the apex ( central punctum ), on removal of this crust, the posterior end of the larva can be seen.
• Crawling sensation,
• Fever.

If the condition is left to itself, in due course the larva dilates the opening by means of its posterior end and eventually escapes, and crawls away and becomes a pupa.

Classification of Myiasis
a)Ecological Classification of myiasis;

• 1)Specific/obligatory Parasite dependent on host for part of its life cycle
• 2)Semispecific/facultative ;  Primary; The fly-larva is the true cause of the condition (Free living and initiates myiasis). Secondary; The fly-larvais a secondary invader (Free living and unable to initiate myiasis).  Tertiary; Free living and unable to initiate myiasis; may be involved when host is near death.
• 3)Accidental/pseudomyiasis;  Free-living larva & not able to complete its life cycle; causes pathological reaction when accidentally in contact with the host

b)Anatomical classification of myiasis
Classification by Zumpt      Classification by Bishopp               Classification by James
Sanguinivorous                     Bloodsucking                                  Bloodsucking

Dermal/subdermal                Tissue-destroying                            Furuncular
                                              Subdermal migratory                      Creeping
                                                                                                      Traumatic/wound
                                                                                                      Anal/vaginal

Nasopharyngeal                  Infestation of the head passages        Nose, mouth, sinuses
                                                                                                       Aural
                                                                                                       Ocular

Intestinal                             Intestinal/urogenital                           Enteric
                                                                                                       Anal/vaginal

Urogenital                          Intestinal/urogenital                            Bladder, urinary passages
                                                                                                       Anal/vaginal


Diagnosis
This is solely clinical;
Patients gives history of traveling to an endemic area or insect bite.
elevated immunoglobulin E, marked Eosinophilia and leukocytosis can be seen on Laboratory investigation
Dermoscopy; identifies the posterior parts of the maggot within a lesion. The examination reveals a central opening surrounded by dilated blood vessels and a yellowish structure with black barblike spines in Furuncular Myiasis.
Rhinoscopy Can be used to diagnose Nasal Myiasis.
Ultrasound confirms cases of furuncular myiasis and helps in the complete removal of the larva. A definitive diagnosis of myiasis can be achieved if larval movement is detected during the ultrasound. Color Doppler sonography has proven to be useful for the detection of the larvae when ultrasound is not able to detect it.


Differential Diagnosis
Furunculosis, Insect bite, Abscess,Cellulitis, Pyoderma, Inflamed cyst, Tungiasis, Delusional Parasitosis,
Labial cases may be confused with labial cellulitis.
Breast myiasis may be confused with periductal mastitis, benign mass with microcalcification, and inflammatory carcinoma.
Clinical and radiologic confusion with arteriovenous (AV) malformation and hemangioma occurred in one case of preauricular myiasis.
herpes simplex, helminthic cutaneous larva migrans, gnathostomiasis, sparganosis.
Hypereosinophilic syndrome,
Exaggerated arthropod reaction,
Foreign body reaction,
Lymphadenopathy,
Onchocerciasis (River Blindness)

Treatment
The following methods can be used in the treatment of Myiasis;
1)Occlusion/suffocation approaches- This method prevents the larva from having access to atmospheric Oxygen, thus forcing it to migrate to the surface. To achieve this, place petroleum jelly, liquid paraffin, beeswax, heavy oil, or bacon strips over the central punctum.

2)Systemic/topical ivermectin; An alternative treatment for all types of myiasis is oral ivermectin or topical ivermectin (1% solution), proven especially helpful with oral and orbital myiasis.

3)Surgical removal with local anesthesia; This is an invassive proceedure, anasthetize locally  with lidocaine. After removal of the larvae, antiseptic dressings, thorough cleansing, and debridement are indicated.

4)Wound Debridement for Wound myiasis; irrigate wound to eliminate the larvae from the wound or surgical removal. Application of chloroform, chloroform in light vegetable oil, or ether, with removal of the larvae under local anesthesia, has been advocated for wound myiasis.

Complications
Secondary bacterial Infection
Cellulities
Local enlarged lymph nodes (lymphoadenopathy)
fistula formation.
Cerebral infestation
Death

Oral Myiasis (Picture Credit; Reddit)

NOTES
1) Aydin E, Uysal S, Akkuzu B, et al. Nasal myiasis by fruit fly larvae: a case report. Eur Arch Otorhinolaryngol. Dec 2006;263(12):1142-3.

2) Dorland's Medical Dictionary for Health Consumers. © 2007 by Saunders, an imprint of Elsevier, Inc

3) Fabio Francesconia and Omar Lupi. Myiasis Clin Microbiol Rev. 2012 Jan; 25(1): 79–105. 

4) Hope FW. 1840. On insects and their larvae occasionally found in the human body. Trans. R. Entomol. Soc. Lond. 1840: 256–271

5) James MT. 1947. The flies that cause myiasis in man, p 1–175 U.S. Department of Agriculture miscellaneous publication no. 631. USDA, Washington, DC

6) James, WD, Berger, TG, Elston, DM. Myiasis. In: Andrews' Diseases of the Skin. 11th ed. Elsevier; 2011:438

7) Masoodi M, Hosseini K. External ophthalmomyiasis caused by sheepbotfly (Oestrus Ovis) larva: a report of 8 cases. Arch Iran Med. 2004;7:136-139.

8) Sharma H, Dayal D, Agrawal SP. Nasal myiasis: review of 10 years experience. J Laryngol Otol. May 1989;103(5):489-91.