Adverse reactions to the processionary caterpillar: irritant or allergic mechanism?

Float like a Butterfly, Sting like One Too

Rash after contact with butterflies has not been previously reported in the medical literature to our knowledge. We describe potentially the first suspected case of a cutaneous reaction to the Compton tortoiseshell butterfly (Nymphalis vaualbum) in a young boy who developed urticaria after the modified hairs of the butterfly embedded within his finger. His urticaria improved through treatment with oral and topical steroids as well as systemic antihistamines. This case report expands the variety of insect species that may cause human disease and should raise awareness for this possible reaction.

Population Explosions of Tiger Moth Lead to Lepidopterism Mimicking Infectious Fever Outbreaks

Lepidopterism is a disease caused by the urticating scales and toxic fluids of adult moths, butterflies or its caterpillars. The resulting cutaneous eruptions and systemic problems progress to clinical complications sometimes leading to death. High incidence of fever epidemics were associated with massive outbreaks of tiger moth Asota caricae adult populations during monsoon in Kerala, India. A significant number of monsoon related fever characteristic to lepidopterism was erroneously treated as infectious fevers due to lookalike symptoms. To diagnose tiger moth lepidopterism, we conducted immunoblots for tiger moth specific IgE in fever patients' sera. We selected a cohort of patients (n = 155) with hallmark symptoms of infectious fevers but were tested negative to infectious fevers. In these cases, the total IgE was elevated and was detected positive (78.6%) for tiger moth specific IgE allergens. Chemical characterization of caterpillar and adult moth fluids was performed by HPLC and GC-MS analysis and structural identification of moth scales was performed by SEM analysis. The body fluids and chitinous scales were found to be highly toxic and inflammatory in nature. To replicate the disease in experimental model, wistar rats were exposed to live tiger moths in a dose dependant manner and observed similar clinico-pathological complications reported during the fever epidemics. Further, to link larval abundance and fever epidemics we conducted cointegration test for the period 2009 to 2012 and physical presence of the tiger moths were found to be cointegrated with fever epidemics. In conclusion, our experiments demonstrate that inhalation of aerosols containing tiger moth fluids, scales and hairs cause systemic reactions that can be fatal to human. All these evidences points to the possible involvement of tiger moth disease as a major cause to the massive and fatal fever epidemics observed in Kerala.

Size and dispersion of urticating setae in three species of processionary moths

Larvae of the processionary moths of the Palaearctic region bear urticating setae that are released against vertebrate predators, especially insectivorous birds. A few species are pests of forest and urban trees and, consequently, may threaten human and animal health during outbreaks, causing dermatitis, conjunctivitis and respiratory distress. Although some studies provide detailed information about the setae, particularly those of the pine processionary moth Thaumetopoea pityocampa, there is little knowledge on the morphological traits of the setae and their release by the larvae. In the present study we identify major traits of the setae of 3 species of processionary moth, T. pityocampa, T. pinivora and T. processionea, which are potentially helpful in the understanding of setae dynamics in the environment: (i) diameter and length of setae and (ii) analysis of dynamical properties of the setae in the airborne state. Setae are highly variable in size, with bimodal distribution in T. pityocampa and T. pinivora; in these 2 species, short and long setae are interspersed within the integument fields where they occur. The difference in the seta size has important consequences in dispersion, as smaller setae can spread 5 times further than their bigger counterparts. This information is relevant for a full understanding of the defensive importance of larval setae against natural enemies of the processionary moths, as well for elucidating the importance of the processionary setae as air pollutants, both close to the infested trees and at longer distances.

Beware of the caterpillar: Anaphylaxis to the spotted tussock moth caterpillar, Lophocampa maculata

We present a case report of a 5-year-old boy with presumed anaphylaxis to the caterpillar, Lophocampa maculata, manifesting as the acute development of diffuse urticaria and progressive dyspnea. This reaction required prompt treatment with antihistamines and a bronchodilator. Allergen scratch testing with a homogenized caterpillar extract suggests that immunoglobulin E–mediated type I hypersensitivity as the pathophysiological mechanism responsible for the boy's anaphylaxis. This case report represents the first documented occurrence of an anaphylactic reaction to Lophocampa maculata and adds to the rare incidence of documented hypersensitivity to the order Lepidoptera.

Skin Reactions to pine processionary caterpillar Thaumetopoea pityocampa Schiff

Pine caterpillar, Thaumetopoea pityocampa Schiff, is a phyto- and xylophagous lepidopteran, responsible for the delay in the growth or the death of various types of pines. Besides nature damage, pine caterpillar causes dermatological reactions in humans by contact with its irritating larvae hairs. Although the dermatitis occurs among outdoor professionals, it is primarily extraprofessional. Contamination generally occurs in pinewoods, rarely in cities. Means of contamination comprise direct contact with the nest or the processional caterpillar and indirect contact with air dispersed hairs. The dermatitis is generally observed in late spring and particularly from April to June, among campers and tourers. The eruption has its onset 1-12 hours after contact with the hairs and presents with intense and continuous itching. Morphologically, it is strophulus-like and consists of papulous, excoriated, and pinkish lesions on an oedematous base. Diagnosis is usually straightforward. The pathogenetic mechanism of the affection is mechanical, pharmacological, and allergic in nature. Besides skin, T. pityocampa Schiff can involve the eyes and rarely the airways. Despite the considerable damages to humans and nature, pine caterpillar infestation is an underestimated problem; medical literature lists few studies, and often relevant information is referred to local media and popular wisdom.

[Skin reactions on exposure to the pine processionary caterpillar (Thaumetopoea pityocampa)]

The pine processionary caterpillar is the larval form of the Thaumetopoea pityocampa moth. Mediterranean forests regularly suffer plagues of this insect, which has been moving north as a result of global warming. When the small urticating hairs that develop during the last 3 larval stages are shed and can become airborne. If they come in contact with skin, they can cause a variety of reactions, notably contact urticaria and papular rashes. Irritation can also occur if the hairs lodge in the mucosa of the conjunctiva or in the respiratory tract. Several cases of anaphylactic reactions have been reported in recent years. Mechanical (irritative) mechanisms may be involved in the pathogenesis of lesions, or immunoglobulin E-mediated allergic hypersensitivity reactions may be implicated when the process is rapid, recurrent, and progressively more severe.

Caterpillar dermatitis revisited: lepidopterism after contact with oak processionary caterpillar

Caterpillar dermatitis (lepidopterism) is a disease that is caused by butterflies, moths and their caterpillars. Clinical signs and symptoms vary from itchy skin lesions to conjunctivitis, pharyngitis, malaise and anaphylactic reactions. We present the case of two brothers with typical skin lesions of leptidopterism. The older boy showed skin lesions after playing with caterpillars in the garden, whereas his younger brother was affected without direct contact to the caterpillars but only by playing with his brother. As the mother could show two caterpillars, lepidopterism could easily be diagnosed. Under a local therapy with a medium potent corticosteroid cream and a non-sedating orally administered antihistamine, all skin lesions as well as itching disappeared within 1 week.