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Myiasis in North-West Italy: Analysis of clinical cases and procedures of diagnosis and treatment

Magni, P.A. and Dutto, M. (2008) Myiasis in North-West Italy: Analysis of clinical cases and procedures of diagnosis and treatment. In: 6th Meeting European Association for Forensic Entomology (EAFE), 20 - 24 May 2008, Kolymbari, Crete.


INTRODUCTION Many insects live in the same ecological niche occupied by humans entering in close contact with humans and theirs products. They can therefore actively and/or passively produce pathologies that cause minor to severe damages. The “infestation of live vertebrate animals with dipterous larvae, which, at least for a certain period, feed on the host's dead or living tissue, liquid body substances, or ingested food" is defined "myiasis", from Greek Mùia=fly (Zumpt, 1965). Diptera flies that cause myiasis can be distinguished into obligated and facultative parasites: in both cases larvae feed on host’s necrotic tissues, liquids or ingested food for a variable time. Once the larvae mature leave their host in order to find a place where they can moult into the pupal stage and undergo a metamorphosis to transform into imagoes. In countries with good levels of hygiene and moderate climate, myiasis are infrequent events and most of the people suffering such infestation are defenseless, wounded, disabled or have very poor personal hygiene. Moreover there are myiasis caused by occasional ingestion of fly eggs and infestations on people coming back from tropical countries where there is higher incidence of such parasitisms. The observation and the study of myiasis cases help us to choose the best therapy for the patient, but in many cases it also gives details of the real living conditions of some people needing treatment. Moreover, some conditions of myiasis can be important for the calculation of the PMI. MATERIAL AND METHODS The present work consists in the screening of cases of myiasis that have occurred in Piedmont (North-West of Italy) in the years 2003-2006, paying particular attention to the cities of Turin and Cuneo. In this description we have taken into consideration the various anatomical parts of the body infested, the consequent myiasis, the myiasigen agent that provoked it, the health, hygienic, social conditions of the subject and the treatment given to the patient. The removal of the larvae was performed according to the methods previously described in the literature, based on the type of myiasis, on the anatomical region and the condition of the infestation. In the majority of the cases the work of the entomologist and the nurses was accomplished simultaneously. Where possible, the larvae sampled have been preserved for further identification and in some cases the larvae have been placed on pig liver in a controlled environment to complete their development. RESULTS Dermal/subdermal or cutaneous myiasis: the diagnosis of the cutaneous myiasis has turned out to be easier than the other types because it is based essentially on the observation of the infested wound. It has been however necessary to inquire about the eventual presence of larvae in non exposed adjacent tissues. The main treatment was based on the removal of maggots and the accurate disinfection of the infested zones. The attempts of larvae removal by the use of vaseline or paraffin resulted to be of little effect. The disinfection of the infested zones was initially done with hydrogen peroxide, subsequently hydrogen peroxide residues and the resulting debris were washed away from the lesion with sterile physiological solution and finally iodine antiseptic solution was used to aid the asepsis of the wounded skin. For the antibiotic therapy, broad spectrum compounds were used. We examined a total of 32 clinical cases and the myiasigen agents can be ascribed to: Sarcophaga spp., Syrphus sp., Lucilia sp., Wolfarthia magnifica, Musca domestica e Calliphora vomitoria and a case of dipters of the Family Gastrophilidae, wich is a tipical Asian myiasigen agent. Foruncular myiasis: those cases were caused mainly by dipters of tropical areas (Dermatobia hominis, Cordilobia anthropophaga), but also by typical dipters of other types of myiasis, such as Sarcophaga haemorroidalis. The diagnosis is based on the observation and on the analysis of the foruncular formations, which were treated by squeezing the nodule and in some cases by surgical examination. To clean the lesion surgical anaesthetics (lidocain, xilocain) were used and later lesions were cleansed, disinfected and bound as described for the cutaneous myiasis. Similar antibiotic therapy was prescribed. The total number of the foruncular myiasis cases observed in our territory was of only 3 in three years. Myiasis of cavities: the infestations observed were caused mainly by dipters that inhabit typical ecological niches and places where the hygienic conditions are well-known to be poor. The same infesting agents of humans (Oestrus ovis) are also parasites of the breeding animals. The hypothesis of the presence of a cavities myasis is based on annoyance reported by the patients, except for a specific case where the patience reported to feel movement inside the nasal cavity. The procedure of removal of the larvae has included the use of a physiological solution and, in one case, forced expiration. To continue the expulsion of the larvae the patients were advised to visit a specialist of the infested anatomical zone. The total of the cases of cavities myasis was 2 in three years. Rectal myiasis and urino-genital myiasis: the cases reported to our department appear to be linked to poor hygienic conditions and the lack of attendance of subjects incapable of cleaning themselves. Diptera samples were belonging to Fannia sp., a typical agent of this type of myiasis. In Piedmont only one case of urogenital myiasis was found in three years. Enteromyasis and pseudomyiasis: the cases observed reported almost exclusively the presence of Musca domestica as pseudomyiasis agents; their infestations were determined mainly by poor food hygiene. For the patients affected by gastrointestinal myiasis (two in three years) no pharmacological therapy was provided. Monitoring of the presence of larvae in facaes was sufficient. CONCLUSIONS From the studied clinical cases it is possible to deduce that the myiasis observed in the hospitals of North West Italy are the result of poor hygienic conditions and, to a minor extent, associated with accidental ingestions and insect bites, the latter being linked to trips to foreign countries. Much rare are the cases of obliged parasitism, whose incidence is greater in the specific ecological niches of the pathogenic agents. We have not observed any cases of cavity myiasis of the auricular tract (otomyiasis) and migratory myiasis. The optimal therapy for myiasis has turned out to be the mechanical removal of the larvae, followed by disinfection of the area and successive antibiotic therapy using a wide spectrum activity compound. Hospitalisation has only been necessary where the patient or the wound have become serious because of septicaemic events or deep/wide necroses. In all the above reported cases, the elimination of the infesting agents has been accomplished by simply following such methodologies. None of patients who strictly observed therapies and hygiene recommendations has suffered from further infestations and/or linked diseases. The study of the incidence of myiasis in our territory and the dialogue with the social services and the police enforcements allowed us to identify the problem “on-time” and to solve eventual situations of negligence involving a particular portion of the population.

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