Hypersensitivity to Samsum ant

552

statistics (1985)2 as the standard reference. SRRs of 173 (Halton), 152 (Wirral), and 146 (Chester) were found for male subjects at all ages. Lower ratios were seen in all other districts. There is a concentration of petrochemical industrial plants along the upper Mersey estuary, especially around Halton, and these are encircled by these health districts. Slightly lower ratios were found for some other districts that include chemical industries-123 (Macclesfield) and 133 (Warrington). Organic chemicals with high partition coefficients can probably be absorbed by inhalation or ingestion and cross the blood-brain barrier. Those with critical chemical structures may induce malignant disease by interaction with DNA. Highly lipid-soluble

cytotoxic drugs (eg, carmustine, lomustine, procarbazine)

are

absorbed via the gastrointestinal tract, cross the blood-brain barrier, and are active in the treatment of malignant gliomas. Similar mechanisms may be involved in the induction of malignant cerebral tumours.

Mersey Regional Centre for Radiotherapy and Oncology, Clatterbndge Hospital, Bebington, Merseyside L63 4JY,

BLEDDYN JONES UK

CAROL BLEASDALE

Youngsen JH, Ashby D, Hussey RM. Cancer in Mersey: incidence of cancer in Mersey region and its constituent health districts 1983-1987. Liverpool: Mersey Cancer Registry, Mersey Regional Health Authority, Liverpool, 1991. 2. Office of Population Censuses and Surveys. Cancer statistics registration 1985. London: HM Stationery Office, 1990. 1.

Infection after subcutaneous interleukin-2 SIR,-Dr Jones and colleagues (Jan 18, p 181) report a high frequency of bacteriologically proven infection in patients receiving subcutaneous interleukin-2 (IL-2) and interferon-ot (IFNa), which they attribute to IL-2 treatment. They advise careful monitoring of treatment with subcutaneous IL-2, and the investigation of the role of prophylactic antibiotics in this context. We have reported an outpatient regimen with subcutaneous IL-2 in patients with disseminated renal-cell cancer.1 In short, patients received daily subcutaneous injections of 18 x 106 IU IL-2 (EuroCetus, Amsterdam, Netherlands) on days 1-5 in the first week, the dose in the first 2 days of the following weeks being reduced to 9 x 106 IU. Up to January, 1992, 24 men and 18 women (mean age 59 years, range 29-76) received 468 weeks of treatment. We found clinical evidence of infection for which antibiotics were indicated on six occasions (1 3%). 1 patient with a spinal cord lesion and atonic bladder was treated three times for recurrent urinary infections that were related to the urinary catheter. A second patient received antibiotics for a local infection with group B haemolytic streptococci in the leg that was compromised with a thrombotic venous occlusion. 1 patient with multiple lung metastases received treatment for a clinical pulmonary infection, and 1 was treated for a clinical epididymitis. Although routine blood cultures were not done and symptomless bacteraemia cannot be excluded, the low incidence of clinical infection in this group of 42 patients and the absence of symptoms that could be ascribed to bacteraemia suggest that there is no indication for the use of prophylactic antibiotics in patients treated with subcutaneous IL-2 alone. Since no excess of infection in cancer patients receiving IFNa has been reported,2,3 the relation between combination therapy with IL-2 and IFNoc and infection needs further investigation.

J. BUTER Department of Medical Oncology, University Hospital, 9713 EZ Groningen, Netherlands 1.

E. G. E. DE VRIES D. TH. SLEIJFER P. H. B. WILLEMSE N. H. MULDER

Sleijfer DTh, Janssen RAJ, Willemse PHB, et al. Low-dose regimen of interleukin-2

for metastatic renal carcinoma. Lancet 1990; 335: 1522-23. 2. Muss HB. Interferon therapy for renal cell carcinoma. Sem Oncol 1987; 14 (suppl 2): 36-42. 3. Creagan ET, Twito DI, et al. A randomized prospective assessment of recombinant leucocyte A human interferon with or without aspirin in advanced renal adenocarcinoma. J Clin Oncol 1991; 9: 2104-09.

Hypersensitivity to Samsum ant SiR,—Insect sting allergy is usually associated with bees and Among the ants only the more primitive subfamilies have

wasps.

retained their sting.1 Allergic reactions to the sting of the fire ant (Solenopsis invicta and S richteri) are a well-recognised hazard in much of North America.2 Pachycondyla sennaarensis (Mayr), known locally as the "Samsum ant", is widely distributed in the Arabian Peninsula. This small black ant is notorious for its painful sting. We report that the sting of this ant can result in severe anaphylaxis. The only ants previously known to cause IgEmediated allegy belong to the genera Solenopsis and Pogonomyrmex (harvester ants), both in the myrrnicinae subfarnily.3,4 During the period November, 1987, to March 1990,40 patients with generalised reactions to the sting of the Samsum ant were evaluated in the allergy clinic, Tawam Hospital. Some were brought directly to the emergency room and others were referred from elsewhere in the United Arab Emirates. Both groups were seen again later in the allergy clinic for questionnaire and allergy evaluation. Thus, information on signs and symptoms were based mainly on records, whereas information on the time of onset of reactions, history, previous reactions, and so on was provided by the patients in the clinic. Most patients were skin-prick tested with fire ant (S invicta) whole-body extract and a range of common allergens, and a radioallergosorbent test (RAST) was done against these allergens in a reference laboratory. Total serum IgE was measured by radioimmunoassay. We also questioned 40 people who had been stung by the Samsum ant but who had no systemic reaction. Most patients described the ant accurately and some brought specimens to the clinic. Other specimens were sent to the British Museum (Natural History) in London where they were identified as P sennaarensis (Mayr). Most patients were young women with a history of allergy and about half had had four or more generalised rections to the ant sting: No

-

11/29

M/F 32

Mean age (range) History of "allergy"*

(13-64) yr 29

History of anaphylactic reactions to ant sting 3 times 4 times Time of onset of symptoms < 15 min 15-60 min 1-3 h Not known *Mainly asthma and/or allergic rhinitis and/or conjunctivitis. < >

18 22 24 8 5 3

The most common symptoms involved the respiratory system and the skin:

Sign/symptom Respiratory Wheezing Dyspnoea Spasmodic cough without wheezing Laryngeal oedema Laryngeal pruritis without oedema Hoarseness Skin Generalised oedema Generalised urticaria

No

Sign/symptom

No

Gastrointestinal 27 31 5 12

6 5

Vomiting, nausea Abdominal pain Pharyngeal oedema

Neurological Syncope Headache Other

Fatigue/malaise Rhinitis

22 27

Conjunctivitis Chills

3 3 4 5 6 13 12 9 3

We know of 2 other people, known to be allergic to the Samsum ant, who died after its sting; another woman went into coma, with sequelae on recovery; and a 32-year-old woman went into anaphylactic shock after a sting from this ant. 18 of 35 patients tested had skin reactivity and 10 of 36 had specific IgE antibodies to fire ant allergens. 73% (27/37) had total IgE levels above the upper limit of normal for the reference

laboratory (180 IU/mi). As far as we are aware, this is the first report of hypersensitivity reactions to the sting of the Samsum ant. This species is widely distributed in the Arabian Peninsula and in tropical Africa (B. Bolton, personal communication), so it is likely that hypersensitivity reactions do occur elsewhere. Our series suggests that atopic

553

to the sting of this The reactions are similar to those described after stings of Hymenoptera5 and of the fire ant.6 An allergen extract of the ant was not available. Nevertheless, IgE-mediated hypersensitivity was probably responsible for the signs and symptoms in our patients. We do not think that there is a toxic-type reaction to ant venom because of those who asserted that they had been stung, many of them several times, without any systemic reaction. The frequency of positive skin tests and specific IgE antibodies to the fire ant whole-body extract suggests cross-reactivity between the venoms of S invicta and P semaarensis. Cross-reactivity between venoms of bees and wasps is well known, as is that between these venoms and that of the fire ant.’ P sennaarensis is in the ponerinae subfamily, whose members have in their venom phospholipase A (B. Bolton, personal communication), which has also been demonstrated in the venom of S invicta.8

individuals are most at risk of allergic reactions ant.

We thank Dr R. Hutchings, Tawam Hospital, for his support and encouragement and Dr B. Bolton, British Museum (Natural History), for the identification and other information.

Department of Medicine, Tawam Hospital, PO Box 15258, Al Ain, Abu Dhabi. UAE. and Departments of Internal Medicine and Medical Microbiology, Faculty of Medicine and Health Sciences, Al Ain, Abu Dhabi 1 Dumpert K. The social biology

GEORGES DIB ROGER K. FERGUSON

VOJIN SLJIVIC

of ants. Boston: Pitman Advanced

Publishing

Program, 1981. 2 de Shazo RD, Butcher BT, Banks WA. Reactions to the sting of the imported fire ant. N Engl J Med 1990; 323: 462-66. 3. Blum MS. Poisonous ants and their venoms. In: Tu AT, ed. Handbook of natural toxins, vol II. New York: Marcel Dekker, 1984: 225-42. 4. Nordvall SL, Johansson SGO, Ledford DK, Lockey RF. Allergens of the imported fire ant. J Allergy Clin Immunol 1988; 82: 567-76. 5. Muller UR. Insect sting allergy: clinical picture, diagnosis and treatment. Stuttgart: Gustav Fisher, 1990. 6. Rhoades RB, Schafer W1, Schmid WH, et al. Hypersensitivity to the imported fire ant: a report of 49 cases. J Allergy Clin Immunol 1975; 56: 84-93. 7. Hoffman DR, Dove DE, Moffitt JE, Stafford CT. Allergens in Hymenoptera venom XXI. cross-reactivity and multiple reactivity between fire ant venom and bee and wasp venom. J Allergy Clin Immunol 1988; 82: 828-34. 8 Hoffman DR, Dove DE, Jacobson RS. Allergens in Hymenoptera venom XX: Isolation of four allergens from imported fire ant (Solenopsis invicta) venom. J Allergy Clin Immunol 1988; 82: 818-27.

Dorsum of left and right hands showing pattern of baldness induced by acral licking on left.

chronic habit. On later questioning, the patient admitted that hair biting had been a compulsion since school. He denied other forms of self-mutilation. After completing ECT, he was placed on higher doses of fluoxetine (40 mg daily) and hair biting diminished. At 3-month follow-up, he remained greatly improved with only occasional hair biting. At 6-month follow-up, although depressive and most obsessional symptoms remained improved, hair biting had resumed, especially during times of anxiety. Our findings accord with the notion that similar compulsive symptoms may occur in different species. We believe that this case strengthens the argument for the existence of an animal model of OCD.5 These models may facilitate the search for the neurobiological basis of this behaviour and hasten the development of more effective treatments.2.5,6 was a

Institute of Psychiatry, Medical University of South Carolina, Charleston, South Carolina 29425, USA

CHARLES H. KELLNER MARK S. GEORGE CAROL M. BURNS HILARY J. BERNSTEIN ROBERT N. RUBEY JOHN CUSTER TIMOTHY BREWERTON

E, Rapoport J. Treatment of canine acral lick with clomipramine and desipramine. J Am Animal Hosp Assoc (in press) 2. Rapoport JL. Treatment of behavioral disorders in animals. Am J Psychiatry 1990; 1. Goldberger

147: 1249.

Rapoport JL, Wise SP. Obsessive-compulsive disorder evidence for basal ganglia dysfunction. Psychopharmacol Bull 1988; 24: 380-84. 4. George MS, Melvin JA, Kellner CH. Obsessive-compulsive symptoms in neurologic disease: a review. Behav Neurol (in press). 5. Insel TR. Obsessive-compulsive disorder: new models. Psychopharmacol Bull 1988; 3.

Human

equivalent of canine acral lick

SIR,-We report a case of what we believe to be the human equivalent to the canine acral lick, in which dogs compulsively lick their forepaws to the point of skin ulceration.1 Canine acral lick responds well to treatment with antiobsessional agents and not as well to conventional antidepressants, lending support to the idea that it is a compulsive symptom that may be analogous to human obsessive compulsive disorder (OCD)Other compulsive behaviour such as trichotillomania (hair pulling) and onychophagia (nail biting), which have a high comorbidity with OCD, also respond to treatment with antiobsessional agents.3.4 We report compulsive hair biting from the dorsal surface of the hands in a patient with OCD. A 38-year-old man presented with a 2-year history of recurrent obsessional thoughts about genital burning after a troubled sexual liaison. Other obsessional ideas developed including that his "brain snapped", and the sensation that he had "electrical impulses" running down his arms. He recognised that these thoughts were abnormal. He became depressed and was given clomipramine, and rash developed. He then received fluoxetine 20 mg daily, but had severe weight loss in the next few months. Electroconvulsive therapy (ECT) was recommended. Before ECT, neurological tests, routine blood tests, and magnetic resonance imaging were all normal. He underwent 5 bilateral and 5 unilateral ECT treatments (electrode placement was changed due to cognitive side-effects), with considerable reduction in both obsessional and depressive symptoms. During the immediate postictal phase of treatment 6, we noted that he began biting off the hair on his left hand. The dorsum of the hand was nearly denuded of hair (figure), indicating that this

24: 365-69. 6. Lorenz K. On aggression. New York: Bantam Books, 1966.

Dosage of thiacetazone SiR,—Thiacetazone toxicity is still very much a live, and distressing, issue in Africa, and at the World Health Organisation also (WHO Wkly Epidemiol Rev Jan 10, 1992). The drug is widely used in Africa to treat tuberculosis because of its availability and cheapness. Yet many clinicians complain of the frequency of exfoliative dermatitis and Stevens-Johnson syndrome. A visit to Zambia brought this home to me forcefully. The problem is especially acute where tuberculosis is AIDS related. Nunn et al’ recorded this and reported a 3% mortality due to the drug in a series of 111cases. Earlier work had suggested that adverse effects were dose related, but Nunn et al believed that the skin reactions were due to hypersensitivity, while acknowledging it was paradoxical that cutaneous hypersensitivity should be worse in the presence of advanced immunosuppression. WHO guidelines now recommend that thiacetazone should not be used in patients who are HIV infected, but accept that in some countries there is no effective alternative. The possibility of a dose-related element is still worth bearing in mind. Fox,2 in the pre-AIDS era, showed that for an average 60 kg adult, a daily dose of 150 mg (2-5 mg/kg) was safe, but 200 mg caused substantial toxicity. The safety margin was thus small, but there were other advantages, such as good patient compliance and low cost. 2-5 mg/kg is the dose WHO still recommends.3 In a series