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UK in which that infection is rare. Since most of the combined kitsare also as sensitive and specific in detecting anti-HIV-1 as mostanti-HIV-1 kits,2 they are now the HIV screening assays of choice,provided that confirmatory testing for both antibodies is available.In countries where HIV-2 infection is common (and moreanti-HIV-2 positive specimens are therefore available) furtherinvestigation of combined assay sensitivity for anti-HIV-2 is

warranted.

This work was funded by the Department of Health Medical DevicesDirectorate.

PHLS Virus Reference Laboratory,Central Public Health Laboratory,London NW9 5HT, UK

PATRICIA O. ABIOLA

JOHN V. PARRYPHILIP P. MORTIMER

1. Parry JV, McAlpine L, Avillez MF. Sensitivity of six commercial EIA kits that detectboth anti-HIV 1 and anti-HIV 2. AIDS 1990; 4: 355-60.

2. Parry JV, Mortimer PP, MacDonald CA, Kennedy DA. An evaluation of twelvecommercial anti-HIV kits (Department of Health publication STD/90/27).London: Supplies Technology Division, Department of Health, 1990.

Reactive arthritis after unusual salmonellainfections

SIR,-As Dr Todd (Sept 29, p 788) and Dr Cooke (Sept 29, p 790)note, salmonella infections are increasing world-wide. This trend isdue predominantly to Salmonella enteritidis and S typhimurium,although other serotypes contribute.’ The consequences maysometimes be more serious than a short episode of food poisoningsince reactive arthritis may ensue. I report on three such patientsadmitted to the Rheumatism Foundation Hospital, Heinola, inwhom reactive arthritis developed after infections with S saint paul,S montevideo, and Sagona, strains not previously associated withreactive arthritis.Case 1 (36, M). This man, who worked in the food industry, had

a routine stool culture after a trip to Tunis. This was found to bepositive for S saint paul. A week later, polyarthritis developed,affecting the left hip and several finger and toe joints. Latex andWaaler-Rose tests were negative; HLA-B27 antigen positive;erythrocyte sedimentation rate (ESR) 45 mm(h; Widal

agglutination test negative; enzyme immunoassay (EIA) forsalmonella IgM, IgG, and IgA antibodies2 highly positive. Thedisease resolved rapidly with anti-inflammatory analgesic therapy.Case 2 (50, M). He had diarrhoea after a trip to Romania.

S montevideo was recovered on stool culture. A month after theonset of the enteric symptoms, migratory polyarthritis developed,affecting shoulders, wrists, hips, knees, ankles, and multiple fingerjoints. The Widal test was positive; latex and Waaler-Rose testsnegative; HLA-B27 antigen negative; antinuclear antibodies

negative; ESR 41 mm/h. Complete recovery was achieved withdoxycycline and anti-inflammatory analgesic treatment at follow-up 8 months later.Case 3 (44, F). She had fever and diarrhoea during a holiday on a

cruise liner in Europe. Stool cultures revealed S agona excretion for2 months. After another 2 months arthritis of the knee developed.The Widal test was negative, but an EIA for IgG salmonellaantibodies4 was positive. Latex, Waaler-Rose, and antinuclearantibody tests were negative; she was HLA B27 antigen negative;and her ESR was 15 mm/h. Synovial fluid culture and gramstaining were negative. The synovitis was treated with local osmicacid. After 6 months she was almost symptom-free.These three patients had reactive arthritis after infections with

salmonella serotypes not previously associated with that condition.Proof of an aetiological association between bacteria and arthritishas to come from a demonstration of their direct involvement in thedisease, as has been shown for S enteritidis and S typhimurium.3 Theclinical picture of these patients was similar to that described earlierfor salmonella-triggered reactive arthritis, with variable timeintervals between onset of infection and arthritis, clear gastro-intestinal symptoms preceding arthritis, and good prognosis.3-6However, as in case 1, patients with no enteric symptoms beforethe complication have also been reported.’’ When arthritic

complications appear after salmonella infection stool cultures are

often negative, as in two of the above three cases. The laboratorydiagnosis of salmonellosis in such cases depends on the detection ofspecific antibodies in the serum. The increase in the diversity ofsalmonella serotypes associated with reactive arthritis renders theuse of sensitive serological screening tests2,7 of utmost importance.

Department of Medical Microbiology,Turku University,20520 Turku, Finland,and Rheumatism Foundation Hospital, Heinola OUTI MÄKI-IKOLA

1. Hargrett-Bean NT, Pavia AT, Tauxe RV. Salmonella isolates from humans in theUnited States, 1984-1986. MMWR 1988; 37 (SS-2): 25-31.

2. Isomaki O, Vuento R, Granfors K. Serological diagnosis of salmonella infections byenzyme immunoassay. Lancet 1989; i: 1411-14.

3. Granfors K, Jalkanen S, Lindberg AA, et al. Salmonella lipopolysaccharide in synovialcells from patients with reactive arthritis. Lancet 1990; 335: 685-88.

4. Inman RD, Johnston MEA, Hodge M, Falk J, Helewa A. Postdysenteric reactivearthritis: a clinical and immunogenetic study following an outbreak of

salmonellosis. Arthritis Rheum 1988; 31: 1377-83.5. Hannu TJ, Leirisalo-Repo M. Clinical picture of reactive salmonella arthritis.

J Rheumatol 1988; 15: 1668-71.6. Mäki-Ikola O, Viljanen M, Tiitinen S, Toivanen P, Granfors K. Antibodies to

arthritis-associated microbes in inflammatory joint diseases. Rheumatol Int (inpress).

7. Maki-Ikola O, Heesemann J, Lahesmaa-Rantala R, Toivanen A, Granfors K.Combined use of released proteins and lipopolysaccharide in enzyme-linkedimmunosorbent assay for serological screening of yersinia infections. J Infect Dis (inpress).

Occupational infection among anaesthetists

SIR,-Your Nov 3 editorial (p 1103) cites a paper suggesting thatthe incidence of hepatitis B virus (HBV) markers in anaesthetists isgreater than in the general population.1 This paper reported a studyin the USA where prevalence of HBsAg in the general population ishigher than in the UK. In 1987 we showed that HBV markers inanaesthetists in the Oxford region were no more common than inthe general population.2 The annual incidence of acute HBVinfection in surgeons in the UK has also been shown to be lowerthan in Denmark or the USA.1,3This is probably due to screening ofhigh-risk patients and the low incidence of healthy carriers in thegeneral population in the UK.

Although we do not wish to underestimate the risk of HIVtransmission, present data from the UK do not suggest thatanaesthetists are at greater risk than the general population ofacquiring either HBV or HIV infection.

Nuffield Department of Anaesthetics,John Radcliffe Hospital,Oxford OX3 9DU, UK

M. E. SINCLAIRM. ASHBY

1. Berry AJ, Isaacson IJ, Kane MA, et al. A multicenter study of the epidemiology ofhepatitis B in anesthesia residents. Anesth Analg 1985; 64: 672-76.

2. Sinclair ME, Ashby MW, Kurtz JB. The prevalence of serological markers forhepatitis B virus infection amongst anaesthetists in the Oxford region. Anaesthesia1987; 42: 30-32.

3. Berry AJ, Isaacson IJ, Hunt D, Kane MA. The prevalence of hepatitis B viral markersin anaesthesia personnel. Anesthesiology 1984; 60: 6-9.

When should hairy cell leukaemia betreated?

SIR,-Your July 21 editorial (p 149) reviews treatments availablefor hairy cell leukaemia (HCL) but you do not discuss when to treat.The answer depends on the goal of treatment. With an incurabledisease the least toxic and most cost-effective therapy that providesthe best palliation is indicated. Despite the highly effective therapiesyou summarise, HCL not yet been shown to be a curable disease, asan international workshop held in Laguna Niguel, California, onOctober 18-21, 1989, showed.The goal of treatment in HCL remains palliative. Patients with

symptomless and stable disease do not need therapy. The criteriafor symptomless disease are no recurrent infections, no symptomsof anaemia or transfusion requirements, no symptoms caused byorganomegaly, and no constitutional symptoms. Stable diseasemaans stable peripheral blood counts (haemoglobin, granulocytes,platelets) over the previous 3 months, alterations within the normalrange being neglected. Therapy should be started only if