Mite infestations

Eosinophilic Dermatosis of Hematologic Malignancy: Emerging Evidence for the Role of Insect Bites-A Retrospective Clinico-Pathological Study of 35 Cases

Background/Objectives: Eosinophilic dermatosis of hematologic malignancy (EDHM) is a rare cutaneous disorder associated with various hematologic malignancies, most commonly chronic lymphocytic leukemia. Detailed clinicopathologic studies of EDHM are lacking and the pathogenesis remains enigmatic. Initially thought to be a hypersensitivity reaction to insect stings, subsequent reports have challenged this understanding. The prognostic implications of EDHM remain unclear. Methods: A retrospective clinicopathologic study was performed on patients diagnosed with EDHM. Hematologic and dermatologic data were reviewed. Histologic specimens were re-evaluated and lesions were classified into acute/subacute, fully developed, and chronic/regressing. Results: The study included 35 patients. In 80% of these patients, EDHM was diagnosed after the hematologic disorder. Approximately 45% of the cohort experienced hematologic disease progression or relapse, while 65% required therapeutic intervention during the course of their hematologic disease. In total, 15/19 CLL patients had non-mutated IgHV, a marker of a more aggressive hematologic disease course. Dermatologic lesion morphology was heterogeneous, with most lesions occurring on exposed areas, and a significant 94% of patients demonstrated lesion seasonality. Histopathologic findings were consistent with features typically associated with insect bites. In addition, examination of lesions at different chronological stages revealed substantial similarities with Wells syndrome. Conclusions: Our findings support the potential role of insect bites in triggering EDHM in the context of adaptive immune dysfunction. EDHM may be associated with a more aggressive disease course or may be a marker of disease progression. The observed co-occurrence of features typical of Wells syndrome in EDHM patients suggests that these conditions are part of a spectrum of disorders that vary in clinical expression.

Pigeon mite: An underdiagnosed cause of papular urticaria

BACKGROUND

Dermanyssus gallinae, known as bird mite, generally lives on nestlings' featherless skin. Humans are accidentally infected, and itchy dermatitis is induced when the mites are unable to use birds' blood. The diagnosis is difficult due to the very small size and rapid movement of the mites, which make them hard to spot.

CASE PRESENTATION

A 14-year-old male and his mother were referred to the allergy clinic complaining of a 2-week generalized itchy cutaneous papular lesion, unresponsive to antihista-mines, with the feeling of an insect moving on the surface of the skin. Due to the history of recently hatched pigeons nesting on their balcony and finding very small bugs, diagnosed as D. gallinae, they were instructed to clean the pigeon's nest as the source of these parasites, which successfully solved the problem.

CONCLUSION

Bird mite infestation should be considered in the differential diagnosis of recurrent pruritus and urticaria, refractory to conventional treatments. Physicians should be aware of this mite infestation in approach to any patient with papular urticaria.

Adolescent Scalp Dermatitis Associated with Dermatophagoides spp. (Acariformes; Pyroglyphidae) Mite

PURPOSE

Dermatophagoides spp. (Acariformes; Pyroglyphidae), house dust-mite well known as the causative agent of atopic hypersensitivity and allergy could potentially cause severe dermatitis. Herein we report an uncommon case of scalp dermatitis associated with the presence of Dermatophagoides spp.

METHODS

A 17-year old male presented with patchy alopecia on the scalp without intense peeling or itching, surround by unchanged skin and hair. Initially, superficial fungal infection was suspected; however, parasitological examination revealed the presence of live mites.

RESULTS

All the anatomical measurements and parameters from the specimens were compatible with Dermatophagoides spp.

CONCLUSIONS

Dermatophagoides spp. are not yet confirmed as causative agents of parasitic infestation, but the presence of these mites could have caused an allergic reaction followed by dermatitis with mild-to-moderate clinical manifestations. However, true parasitism as well as phoresy could also be considered. The clinical manifestations caused by house-dust mite cannot be easily recognized and the lack of diagnostic tools is a hindrance that often leads to misdiagnosis and inadequate therapy.

In Vivo Observation of Trombiculosis with Fluorescence-Advanced Videodermatoscopy

Trombiculosis is a skin infestation by larvae of mites of the Trombiculidae family. We used fluorescence-advanced videodermatoscopy to diagnose trombiculosis in a woman in Italy with targetoid patches. This method might be useful for identifying atypical manifestations of trombiculosis.

Identification of Trombiculid Chigger Mites Collected on Rodents from Southern Vietnam and Molecular Detection of Rickettsiaceae Pathogen

Trombiculid “chigger” mites (Acari) are ectoparasites that feed blood on rodents and another animals. A cross-sectional survey was conducted in 7 ecosystems of southern Vietnam from 2015 to 2016. Chigger mites were identified with morphological characteristics and assayed by polymerase chain reaction for detection of rickettsiaceae. Overall chigger infestation among rodents was 23.38%. The chigger index among infested rodents was 19.37 and a mean abundance of 4.61. A total of 2,770 chigger mites were identified belonging to 6 species, 3 genera, and 1 family, and pooled into 141 pools (10–20 chiggers per pool). Two pools (1.4%) of the chiggers were positive for Orientia tsutsugamushi. Ricketsia spp. was not detected in any pools of chiggers. Further studies are needed including a larger number and diverse hosts, and environmental factors to assess scrub typhus.

Investigation of a gamasid mite infestation in a UK textile mill caused by Dermanyssus gallinae (DeGeer, 1778) (Mesostigmata: Dermanyssidae) special lineage L1

A recurrent mite infestation affecting a room used to inspect fabric in a UK textile mill was investigated to allay concerns of any potential health risks to factory staff, and to inform the unknown risk of downgrading of the product. The approach integrated conventional morphological examination of adult female mites by referring to published identification keys, with molecular speciation based on amplification of a 16S ribosomal DNA fragment. The methods enabled the mites to be unambiguously identified as Dermanyssus gallinae 'special lineage L1'. Subsequent investigations showed the source of infestation to be pigeons nesting in the air ducts, with the gamasid mites moving into the room once the young birds had fledged. This is the first report of D. gallinae 'special lineage L1' in northern Europe. Previous reports of nosocominal gamasoidosis caused by D. gallinae 'special lineage L1' originating from feral pigeon populations have been from southern Europe. Confirmation of the mite identity was important in allowing the mill to take remedial and preventive action. In this clinical communication, we provide images of the key morphological features used to identify D. gallinae and describe a molecular protocol to confirm 'special lineage L1'.

Infestations, Bites, and Insect Repellents

Infestations and arthropod bite reactions in children are common reasons for presentation to pediatric health care providers. Infestations in children include head lice, scabies, and other mites. Fleas and bed bugs are common causes of bite reactions in children, and papular urticaria is a chronic, recurrent eruption resulting from delayed hypersensitivity to a variety of insect bites. Both infestations and bite reactions may result in severe pruritus with associated sleep disturbance and can be a source of significant distress for patients and families. In this review, we discuss infestations and bite reactions affecting pediatric patients, along with the approach to treatment and prevention of these conditions. [Pediatr Ann. 2020;49(3):e124-e131.].

[Gamasoidosis caused by Dermanyssusgallinae]

INTRODUCTION

Mite parasites can be transmitted from animals to humans and cause prurigo.

OBSERVATION

We describe a case of mite transmission in a 75-year-old woman referred for pruritus and erythematous maculopapular rash. On clinical examination mites were seen on the patient's skin. The mites were collected and characterized using microscopy. The species was identified as Dermanyssusgallinae, also known as the poultry red mite, an ectoparasite that commonly infests bird nests. The source of the patient's contamination was her henhouse, where mites were found in the wooden beams. Molecular analysis by mitochondrial DNA sequencing was performed on a mite collected from the patient and on a mite collected from the henhouse. This analysis confirmed that both belonged to the D. gallinaes.str species, and that the source of contamination was poultry farming.

CONCLUSION

This case describes transmission to a human of the mite D. gallinaes.str via hens, resulting in prurigo, as confirmed by morphological and molecular analysis.

Outbreak of Occupational Dermatitis Associated With Pyemotes ventricosus

Importance

Although Pyemotes species have been known to cause dermatitis, recent reports are rare. During the past 30 years, only 3 outbreaks of dermatitis caused by Pyemotes ventricosus have been reported.

Objective

To analyze the causative agent of skin changes in employees of a company that produced herbal medicines.

Design, Setting, and Participants

This case series includes 18 patients (8 men, 10 women; mean age, 44 years) who contracted unusual dermatitis after an occupational exposure in July and August of 2012 while working for a company that produced herbal medicines. The patients were examined at the Lower Silesia Regional Centre of Occupational Medicine in Wroclaw, Poland.

Exposures

Workers weighed and packed 1 part of the Helichrysum arenarium herb.

Main Outcomes and Measures

We hypothesized the causative agent to be P ventricosus. An examination of the herbal specimens for ectoparasites confirmed the diagnosis.

Results

Initially 16 employees developed pruritic skin changes. Skin lesions with pruritic vesicles on an erythematous base with surrounding swelling and edema were observed. Several employees also developed a flulike illness. After 44 days, 2 new employees presented with the same skin changes. The analysis of working conditions showed that the same part of the H arenarium herb was weighed and packed at that time.

Conclusions and Relevance

We found that changing the time when the herbs were weighed and abandoning gas fumigation containing methyl bromide resulted in the recurrence of an almost forgotten disease.

Gamasoidosis caused by the special lineage L1 of Dermanyssus gallinae (Acarina: Dermanyssidae): A case of heavy infestation in a public place in Italy

Among Gamasina (Acari: Mesostigmata) mites, some dermanyssoid species are known to cause gamasoidosis, a human dermatitis characterized by papulosquamous eruptions and urticarian lesions. We describe a case of mite infestation which occurred in public conference halls in Ferrara (Italy), affecting four people who attended the place and showed signs of gamasoidosis. The mites were collected and characterized using scanning electron microscopy, light microscopy and mitochondrial DNA sequencing (Cytochrome c oxidase subunit I partial CDS). Based on morphological and molecular data, the species responsible for the infestation was identified as the special lineage L1 of the poultry red mite, Dermanyssus gallinae (De Geer) (Acarina: Dermanissydae), a cryptic species known to be associated with pigeons. Rock doves, Columba livia Gmelin (Columbiformes: Columbidae) were roosting on the top of the public building, thus the mites probably gained access to the halls through small window openings. The present case report is the first one providing morpho-molecular identification of a D. gallinae cryptic species responsible of gamasoidosis in Italy.

Syndromic classification of rickettsioses: an approach for clinical practice

Rickettsioses share common clinical manifestations, such as fever, malaise, exanthema, the presence or absence of an inoculation eschar, and lymphadenopathy. Some of these manifestations can be suggestive of certain species of Rickettsia infection. Nevertheless none of these manifestations are pathognomonic, and direct diagnostic methods to confirm the involved species are always required. A syndrome is a set of signs and symptoms that characterizes a disease with many etiologies or causes. This situation is applicable to rickettsioses, where different species can cause similar clinical presentations. We propose a syndromic classification for these diseases: exanthematic rickettsiosis syndrome with a low probability of inoculation eschar and rickettsiosis syndrome with a probability of inoculation eschar and their variants. In doing so, we take into account the clinical manifestations, the geographic origin, and the possible vector involved, in order to provide a guide for physicians of the most probable etiological agent.

Parasitic mites of medical and veterinary importance--is there a common research agenda?

There are an estimated 0.5-1 million mite species on earth. Among the many mites that are known to affect humans and animals, only a subset are parasitic but these can cause significant disease. We aim here to provide an overview of the most recent work in this field in order to identify common biological features of these parasites and to inform common strategies for future research. There is a critical need for diagnostic tools to allow for better surveillance and for drugs tailored specifically to the respective parasites. Multi-'omics' approaches represent a logical and timely strategy to identify the appropriate mite molecules. Recent advances in sequencing technology enable us to generate de novo genome sequence data, even from limited DNA resources. Consequently, the field of mite genomics has recently emerged and will now rapidly expand, which is a particular advantage for parasitic mites that cannot be cultured in vitro. Investigations of the microbiota associated with mites will elucidate the link between parasites and pathogens, and define the role of the mite in transmission and pathogenesis. The databases generated will provide the crucial knowledge essential to design novel diagnostic tools, control measures, prophylaxes, drugs and immunotherapies against the mites and associated secondary infections.

Efficacy of doramectin in Trixacarus caviae infestation in guinea pigs (Cavia porcellus)

The present study was intended to evaluate the efficacy of doramectin against seven naturally Trixacarus caviae infested male guinea pigs. Multiple skin scrapings of all the seven guinea pigs were found microscopically positive for T. caviae mites. Clinically these animals revealed, more or less denuded, very red often thickened, and crustated cutaneous lesions restricted at the sacral region and back. Doramectin 1 % (w/v) was administered intramuscularly at a dose rate of 400 μg/kg once weekly, which resulted in profound improvements in clinical conditions within 14 days after the first doramectin application. It took almost 28 days for the cutaneous lesions to disappear and to witness partial hair coat regrowth. Two moderately infested guinea pigs required only single injection of doramectin to achieve complete parasitological cure, while remaining five (one moderately infested and four severely infested) guinea pigs required two injections of doramectin to achieve complete parasitological cure. No adverse effects were revealed by any of the doramectin treated guinea pigs during the study period. Thus, it can be concluded from the present study that guinea pigs naturally infested by T. caviae mites can be cured safely using two doses of doramectin once in a week.