PARARAMA, A DISEASE CAUSED BY MOTH LARVAE: 72 EXPERIMENTAL FINDINGS’ Leonidas Braga Dias, M.D., and Miguel Cordeiro de Azevedo, M.P.H.3 Contact with hairs (setae) from larvae of the moth Premolis semirufa is known to have painful or crippling effects on the fingers of Brazilian rubber workers. Research on mice exposed to these setae, reported here, provides new information about how this occurs. A caterpiller called “pararama,” larva of the patient of the use of one or more fingers, moth Premolis semirufa, has previously been presenting a clinical picture corresponding to reported by Vianna and Azevedo (I) to have ankylosis. affected at least 24 rubber workers at a Martins (4) and Dias (5) have confirmed plantation named Granja Marathon (Marathon observations in Belterra, where Machado (6) Farm) in the municipality of Sa’o Francisco, says that the proportion of rubber plantation which is located in Brazil’s north-central state workers affected by this diseasehas been as _ of Para. These authors have termed the delayed high as 40 per cent. Ma&do (T), in a radio- clinical manifestations of the condition “para- logical study, found no alterations on the rama,” using the caterpiller’s local name. (The surface of finger joints, but notedperiarticular, larvae are also frequently referred to simply as edematousand fibrous alterations of underlying Zagar&s-caterpillers.) tissues. The presenceof these larvae has been noted Lacking further data of this type, we under- for many years at another location as well, the took experimental research on mice, using the rubber plantations of Belterra in the Para larvae indicated by rubber workers as the cause municipality of Santarem. of their lesions, to investigate development of The lesions frequently observed after ac- the articular injuries cited in these clinical and cidental contact with the larvae of certain radiological reports. lepidoptera, their cocoons, or their adult forms are itching, blistered, pruriginous processesin- Materials and Methods volving allergic and toxic manifestations. Both isolated casesand epidemicshave been reported Well-developedlarvae (Picture 2) collected (Gusmao,et aZ.,-2); more recently, such lesions from the trunks of rubber trees (Heveabrasil- have also been considered an occupational iensis) on Granja Marathon were brought to the disease(Katzenellenbogen-3). laboratory in screenedboxes, where they were Contact with a pararama causesimmediate kept, and were fed with leavesfrom the same intense itching (pruritus), hyperemia, and local trees. Several of them formed cocoons during edema. It also gives rise to chronic manifesta- the first 24 to 48 hours and molted a few days tions later on, and these sometimesdeprive the later. Some adult forms were mounted and sent to Professor Lauro Travassos Filho at the Sa’o ‘Work carried out at the Evandro Chagas Insti- Paulo State Agriculture Ministry’s Zoology tute-Foundation of the Oswald0 Cruz Institute, Beldm, Pari. Department; there the specieswas identified as 2Chief of the Pathology Section of the Evandro Premolis semirufa (Walker, 1856; Hampson, Chagas Institute; Assistant Professor of the Center f?r Biological Sciences of the Federal University of Para. 1901) a moth of the superfamily Noctuoidea, SDirector, Evandro’Chagas Institute. Family Arctiidae (seephotograph). In addition, 9 10 PAHO BULLETIN . voz. VII, No. 3, I973 some mature larvae were subjected to macro- setae had inflicted injury, which occurred scopic and histologic examination. Three types regardless of whether they came from living of surface hairs (setae) were macroscopically larvae, dead and dried larvae, or cocoons. isolated; these have been classified as large, Therefore, subsequent experiments used only medium, and small (Picture 2). The large ones, dried larvae from which the large and medium measuring up to 3 cm in length, are located : setaehad been removed. chiefly on the lateral surfaces of the thoracic and abdominal segments,emerging from small protuberances. The medium-length ones are Experiment A: about 1 cm long and are located on the dorsal Five three-day-old mice were put in a glass surfaces of the first and seventh abdominal segments,there being two tufts of setaeon each container with somedried larvae and kept there segment. The small ones, measuring 1.5 to 2 for five minutes. The container was shakenfour mm in length, are also dorsally situated, and are times, using circular and lateral movementsto found on abdominal segments two through increase the animals’ contact with the larvae. eight; they occur in two pairs of tufts on each One mouse was sacrificed two hours later, two segment, were sacrificed 24 hours after exposure,and the The various types of setae are also woven last two were sacrificed 48 hours after expo- into the pararama’sdun-colored cocoon, which sure. is shapedlike a spindle (except that one of the sides is flattened where the cocoon is attached Experiment B: to a surface). The small setae are erect and disposed perpendicularly about the outer sur- Eight seven-day-old mice were exposed to face, giving the cocoon a velvety appearance larvae as in Experiment A; in addition, before (Picture 3). adding the mice the inside of the container was sprayed with small setae extracted from another larva. The animals were exposedfor 10 minutes and the receptacle was shaken six To prepare slides for histologic examination times. Four animals were sacrificed 24 hours (Pictures 4 and 5) larval segmentswere sliced later and the others were sacrificed on the transversely,fixed in formaldehyde, and treated fourth day after exposure. with paraffin. Dead larvae were dried in an oven at 37’C Experiment C: and were stored for later use in the experiments reported here. Five full-grown mice were exposed as in Experiment B. Three were sacrificed after 24 hours and the other two on the fourth day after Experiments exposure. Preliminary Test Experiment D: Setae from living larvae, dead and dried larvae, and cocoons were placed on the shaved Four full-grown mice were exposed as in abdomens of adult mice and affixed with Experiment B on four separate occasions, at adhesivetape. Each kind of seta from each type intervals of four days. They were then sacri- of source was tested on two animals,so that 18 ficed 18, 25, 32, and 39 days after the last mice were used in all. exposure. When these mice were sacrificed 24 and 48 8 8 m hours later, it was observedthat only the small Braga Dias and Cordeiro de Azevedo . PARARAMA 11 (1) Adult form of the moth Premolis semirufi. the small setae and their sharp tips. (Carbol-fuchsin (2) The larva pararama, after being fixed in for- light green solution, approximately 120X.) maldehyde. Arrows indicate the large (G), medium (6) Section of a mouse foot 18 days after expo- (M), and small (P) setae. sure, showing part of a seta in a synovial bursa (3) Pararama’s spindle-shaped cocoon. The surface evidencing a fibrous and slightly granulomatous re- is covered with small setae. sponse. (Hematoxylin-eosin, approximately 250X.) (4) Tissue slide made from a tuft of small setae; (7) Section of a mouse foot 25 days after expo- secretory cellular elements may be seen under the sure, showing a seta under the periosteum accom- cuticle. (Carbol-fuchsin light green solution, approxi- panied by a fibrous, histiocyte-producing reaction. mately 50X.) (Carbol-fuchsin light green solution, approximately (5) Detail of a tuft, showing the tubular nature of 250X.) 12 PAHO BULLETIN . Vol. VII, No. 3, 1973 All the animals were anesthetizedwith ether cytic infiltration and edema.Occasional hemor- prior to being sacrificed. The newborn animals rhagic foci were also observed in the lungs, were then fixed whole, after their cranial, although no setae were observed in the lung thoracic, and abdominal cavities had been tissue samplesexamined. opened. To examine the adult animals, slides Similar results were observedin the Experi- were made from portions of the abdominal ment B mice sacrificed24 hours after exposure. wall, snout, perianal tissue,hind feet and lungs, In addition, setae were found in the deep A 10 per cent formaldehyde solution was used tissuesof the feet, in the corium of the mucosa to fix the samples,After fixation, the feet were of the mouth and tongue, and frequently in the decalcified in an aqueoussolution of S per cent corium of the snout. The mice sacrificed after formic acid. Standard techniques for embed- four days also showedsetae in these areas,there ding in paraffin and sectioning were used; the having meanwhile been changes in the local resulting 6-micron sections were stained with reaction, with partial replacement of neutro- hematoxylin-eosin and carbol-fuchsin light philic elements by histiocytes, giving the ap- green solution. pearanceof a granulomatousreaction to foreign bodies. Experiment C animals sacrificed 24 hours Results after exposure showed some setae within the abdominal wall, in the perianal tissue, in the There was virtually no evidence of large or dermis of the snout, and in the feet. The local medium setaein the tissuesof mice exposedto changespreviously mentioned (neutrophilic in- these types in the preliminary tests. There was filtration and edema) were observed. The two just one case-that of a mouse that had been animals sacrificed after four days showed sacrificed 24 hours after exposure to medium results similar to those obtained in the Experi- setae-in which we found two reactive dermal- ment B mice sacrificed after four days. Setae epidermal foci with very superficial leukocytic were found in the sametissues, accompanied by infiltration. However, the small setae did pene- a similar granulomatousresponse. In one animal trate the tissues of the exposed animals, being a granuloma in the pulmonary parenchymawas found later at the opening of sebaceousglands, found to have formed around a seta. throughout the epidermis, at various levels of In Experiment D, only the hind feet of the the dermis, sometimes in the abdominal mus- animals were examined.