Myiasis is a disease caused by ectoparasitic infestations of the skin, cavities and wounds by larvae of a wide variety of dipteran flies (Calvopina et al 2020). Myiasis has a worldwide distribution, but is more frequently reported in tropical and temperate tropical areas as well as in nomadic areas(Francesconi et al 2012; Faridnia et al 2019). Myiasis is commonly seen in domestic and wild animals but occurs rarely in man also(Singh et al 2015). Based on the relationship between host and fly maggot larval parasitism, myiasis is categorized into exclusive parasitism and parthenogenetic parasitism. Specialized parasites feed on live host tissues, parthenogenic parasites tend to feed on cadavers or necrotic tissues, decompose tissues, and occasionally infect humans(Francesconi et al 2012; Calvopina et al 2020). The myiasis induced by specialized parasitism can cause complications due to larvae feeding on healthy tissues, which can be life-threatening in severe cases(Calvopina et al 2020). Therefore, patients with suspected myiasis should be diagnosed in a timely manner and treated effectively as early as possible.
Myiasis can be classified into various types based on the location of infection. Among these, cutaneous and ocular myiasis are the most prevalent, while nasal myiasis is less commonly reported(Kuria et al 2020). However, because of the proximity of the nasal cavity to the sinuses, eyeballs, and cranial cavity, once the fly maggots migrate into this location may lead to serious consequences, so nasal fly maggot disease should not be underestimated!
Nasal myiasis most often occurs in the presence of chronic nasal disease, the nasal cavity of such patients purulent secretions can attract flies into the nasal cavity, inducing nasal myiasis( Kuo et al 2021;Hoyer et al 2016). Nasal myiasis occurs when the female fly oviposits near or in the mucous membrane of the nasal cavity, followed by the first maggots burrowing through tissue(Bosmia et al 2017). Myiasis can also be acquired as a result of poor sanitation in an area with a high concentration of flies. Although the patient in this case has been living in Tianjin for a long time, it was found through research that the patient lived in a village in the suburban county of Tianjin, and her neighbors were engaged in animal husbandry, and the sanitary environment at home was poor, so the occurrence of mosquitoes and flies entering the nose could not be ruled out. In addition, the patient was admitted to the hospital with a sinus CT suggestive of sinusitis, the patient was in an impaired state of consciousness at the time of admission, and her family members were to account for the patient's history of rhinitis, so it was difficult to determine whether the patient was suffering from chronic rhinitis induced by flies parasitized in the nasal cavity, or sinusitis due to the flies parasitized in the nasal cavity. Previous reports have documented cases of fly maggots being found in patients with impaired consciousness after being admitted to the hospital(Kuo et al 2021; Zobairy et al 2023; Babamahmoudi et al 2012). Interestingly, these cases have involved patients with a history of diabetes mellitus, similar to the patient in this particular case. A review of the literature showed that case reports of rhinoceros fly maggots in patients with diabetes mellitus are not uncommon(Lubis et al 2019; Surayya et al 2021; Uysal et al 2018). This suggests that people with diabetes may be more susceptible to myiasis. Regarding this inference, it has been reported that susceptibility factors for human myiasis include poor hygiene, advanced age, psychiatric illness, rural background, low socio-economic status, homelessness and diabetes(Francesconi et al 2012; Faridnia et al 2019).Therefore, it is more important to prevent fly maggots in diabetic patients and in some patients with psychiatric or other factors that limit their consciousness.
Upon diagnosis of nasal myiasis, immediate treatment is crucial to prevent tissue damage and associated complications. The primary approach to managing myiasis involves clearing the larvae. Current treatment options include local anesthetic debridement, endoscopic forceps removal, creating a toxic and anaerobic environment using turpentine solution to kill and clear the fly larvae, and saline rinses for clearance(Sangalette et al 2023; Sayeed et al 2019). Additionally, appropriate anti-infective therapy should be administered based on the patient's clinical condition. In this case, the patient presented with unconsciousness, respiratory failure, and pneumonia. To prevent aspiration and exacerbation of pneumonia, the patient underwent nasoscopic saline rinsing of the nasal cavity three times a day for four consecutive days. Additionally, anti-inflammatory treatment was administered to prevent intracranial infection. Following four days of treatment, nasal microscopy revealed complete clearance of maggots from the patient's nasal cavity. Upon discharge from the hospital, the patient was followed up for one month and showed a favorable prognosis with no further adverse symptoms.
In comparison to the southern and northern pastoral regions of China where fly maggot disease is more commonly reported, Tianjin is situated in the North China Plain where the incidence of this disease is relatively rare. However, this particular case serves as a reminder that fly maggots can still be contracted in Tianjin due to frequent exposure to flies and poor hygiene practices. It is important for healthcare professionals to be aware of the possibility of myiasis in their daily diagnosis and treatment efforts. In the case of ICU patients, who often present with critical conditions and impaired consciousness, it is crucial to integrate clinical manifestations with the individual patient's circumstances. This integration aids in promptly differentiating myiasis and implementing early intervention measures to prevent the worsening of the patient's condition.