infection rises the number of doctors infected during their clinical duties will also rise. Despite this doctors have treated and will, I hope, continue to treat HIV positive patients as they would any other person. Ethics demands no less. Doctors put their own lives at risk. Can it be right that the few who succumb should be the only HIV positive group to be let down by the NHS? LAURENCE COOK

Oldham, Lancashire OL4 5RT 1 Erskine JA. Guidelines for doctors with HIV infection. BMJ 1991;303:784. (28 September.)

Notification of communicable diseases SIR,-Using the example of hepatitis A, Dr Ruth White and colleagues highlight the inadequacies of the current system for notifying communicable disease.' The current system for notifying cases of food poisoning is inappropriate. General practitioners are asked, without any guidance on what is a practical, working definition of food poisoning, to notify suspected cases of food poisoning by post (usually second class post) to the medical officer for environmental health or the consultant in communicable disease control or to the local authority's environmental health department. Environmental health officers are then asked, on the basis of this information, to devote scarce resources to tracking down purported cases of food poisoning, often after considerable delay, and to what end? If we are in the business of preventing transmission of foodborne illness we need to know whenever patients with suspected food poisoning pose a risk to the public health-as with a food handler, for example-and we need to know quickly, so that we can focus attention on these cases. Early reporting of cases is also vital for prompt identification and control of outbreaks. Dr White and colleagues also mention incomplete reporting ofmeningitis but do not address the importance of timely notification. A recent survey of notification of meningococcal disease in Norwich Health District identified a median delay of 4-3 days from the date of the formal notification to the date of its receipt, while the median delay from date at onset of symptoms to receipt of notification was 103 days. It is only because I too have the invaluable cooperation of my colleagues in the public health laboratory in reporting such cases that any timely public health interventions can be made. The Review of Law on Infectious Disease Control has suggested that some of these diseases in which early action is necessary require improved methods of notification.2 Mindful of the need to safeguard confidentiality, must we wait for changes in legislation before improving our system of notification and of communication among clinicians, microbiologists, and public health physicians? We must educate and motivate our clinical colleagues to make appropriate and timely notifications of communicable diseases. BRYAN JEFFERSON HEAP Department of Public Health Medicine, Norwich Health Authority,lSt Andrews's Hospital, Norwich NR7 OSS

1 White R, Cheesbrough J, Zala D. Notification of hepatitis A. BMJ' 1991;303:782-3. (28 Sept.) 2 Department of Health. Review of la2u on infectious disease control-consultation documnent. London: DoH, 1989.

Notification of viral hepatitis SIR,-The letter from Dr Ruth White and colleagues on the poor rates of notification of

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hepatitis A' is relevant also to other types of hepatitis. The ratio of subclinical and anicteric infections to clinical infections with all types of viral hepatitis varies with age and outbreaks but is generally accepted to range from 5:1 to as many as 20:1. Notification rates of acute clinical hepatitis are known to be notoriously unreliable and vary among countries, districts, and indeed medical practices and with seasonal factors. Cases of subclinical and anicteric hepatitis are not reported, except perhaps in well circumscribed outbreaks. In general, the published prevalences are the minimum figures available. An example is the finding of hepatitis A antibodies in 64 5% of blood donors screened in the North East Thames region.2 Furthermore, 4-6% of the general population in metropolitan areas of Britain have hepatitis B surface antibody, indicating past infection, and one in 300 are carriers of hepatitis B virus in metropolitan London (World Health Organisation laboratory report, 1985). If positivity for hepatitis B core antibody on radioimmunoassay is included, then, based on the blood donor population in the United Kingdom (which is highly selected), up to another 2-3% have been infected with hepatitis B virus, although many would also have antibody to the surface antigen. My two final comments are based on evidence from the United States and, in particular, Sweden (where notification systems are widely believed to be excellent). Serological surveys of the prevalences of hepatitis B surface antigen and hepatitis B surface antibody among adults in the United States suggest a much higher attack rate of hepatitis B infection than reported-perhaps three to 10 times higher.' In Sweden the data suggest that only 5% of (hepatitis A) infections in 20-25 year old adults resulted in reported disease.4 Notification of hepatitis not only provides important information on the epidemiology of the infection and measures for prevention but is also essential for those designing effective policies for immunisation-at present against hepatitis B (under review) and shortly against hepatitis A.' ARIE J ZUCKERMAN World Health Organisation Collaborating Centre for Reference and Research on Viral Diseases, Royal Free Hospital School of Medicine, London NW3 3PF

1 White R, Cheesbrough J, Zala D. Notification of hepatitis A. BMJ 1991;303:782-3. (28 September.) 2 Scott NJ, Harrison JF, Zuckerman AJ. Hepatitis A antibody in blood donors in North East Thames region: implications to

prevention policies. Epidemiol Infect 1989;103:377-82. 3 Gerety RJ, Tabor E. The epidemiology of hepatitis B. In: Gerety RJ, ed. Hepatitis B. New York: Academic Press, 1985:80. 4 Papaevangelou GJ. The epidemiology of hepatitis A. In: Gerety RJ, ed. Hepatitis A. New York: Academic Press, 1984:117. 5 Zuckerman JN, Cockcroft A, Griffiths P. Hepatitis A immunisation. BMJ 1991;303:246-7. (27 July.)

Urethral stricture after cardiac surgery SIR,-Mr M A Johnston and colleagues report the late presentation of a urethral stricture in a child after cardiac surgery.' The aetiology of such strictures is unknown but may be related to an inflammatory reaction to latex23 or the lubricant.4 Traumatic insertion of the urethral catheter (more likely to occur when the patient is anaesthetised) has been implicated,' as has the use of large catheters, which may cause ischaemic necrosis and blockage of urethral glands with resultant inflammation and fibrosis.2 Urethral ischaemia during cardiac surgery may also be a factor.5 6 After an epidemic of urethral stricture in adults undergoing aortic surgery I and coworkers abandoned urethral catheterisation in favour of a fine soft flexible polypropylene catheter introduced suprapubically.7 In over 200 subsequent cases no further urethral strictures occurred in men and no

morbidity was associated with use of the catheter. A similar suprapubic method of drainage would be appropriate for children undergoing cardiac surgery. The catheter may be inserted at the beginning of the procedure by a direct stab technique, if necessary after the bladder has been filled by means of a catheter placed just inside the external urinary meatus. Suprapubic catheters also allow a trial of micturition before they are removed, thus obviating the occasional need for repeated urethral catheterisation. MICHAEL D DINNEEN Department of Paediatric Urology, Hospitals for Sick Children, Great Ormond Street, London WC1N 3JH 1 Johnston MA, Hughes DA, Azmy AF. Late complications of undetected urethral stricture after cardiac surgery in a child. BM3r 1991;303:772-3. (28 September.) 2 Edwards LE, Lock R, Powell C, Jones P. Post-catheterisation urethral strictures. A clinical and experimental study. Br J7

Urol 1983;55:53-6. 3 Ruutu M, Alfthan 0, Heikkinen L, Jarvinen A, Konttinen M, Lehtonen T, et al. Unexpected urethral strictures after shortterm catheterisation in open-heart surgery. Scand J Urol Nephrol 1984;18:9-12. 4 Smith JM, Neligan M. Urethral strictures after open heart surgery. Lancet 1982;i:392. S Prabhu S, Cochran W, Raine PAM, Azmy AF. Postcatheterisation urethral strictures following cardiac surgery in children. Jf Pediatr Surg 1985;20:69-71. 6 Abdel-Hakim A, Bemstein J, Teijeira J, Elhilali MM. Urethral stricture after cardiovascular surgery, a retrospective and a prospective study. J Urol 1983; 130:1100-2. 7 Dinneen MD, Wetter LA, May ARL. Urethral strictures and aortic surgery. Suprapubic rather than urethral catheters. EurJ Vasc Surg 1990;4:535-9.

Aprotinin and cardiac surgery SIR,-In their editorial on aprotinin and cardiac surgery Dr Beverley J Hunt and Professor Magdi Yacoub recommend using normal doses of heparin when aprotinin is used despite prolongation of the activated clotting time.' A recent report suggests that this prolongation of the clotting time may be an artefact caused by an interaction between the celite activator normally used in the activated clotting time tube and aprotinin in the presence of heparin.5 Wang et al measured activated clotting times when aprotinin was added to blood containing heparin in activated clotting time tubes containing either celite or kaolin as the activator.2 In the celite tubes the activated clotting time was considerably prolonged when aprotinin was added whereas no change was observed in the kaolin tubes. Interestingly, aprotinin had no effect on the activated clotting time before heparin was added and after reversal of the effect of heparin with protamine. The recommendation in the editorial to use normal doses of heparin with aprotinin despite prolonged activated clotting times seems to be prudent when celite is used as the activator. More investigations are needed to confirm this initial report and to determine the importance of any interactions between aprotinin and the activator used. D W BETHUNE

Papworth Hospital, Cambridgeshire CB3 8RE 1 Hunt BJ, Yacoub M. Aprotinin and cardiac surgery. BMJ

1991;303:660-1. (21 September.) 2 Wang J-S, Hung W-T, Karp R, Lin C-Y. Increase in ACT of heparinized blood in patients on aprotinin is caused by the celite activator. Abstracts presented at the 13th annual meeting of the Society of Cardiovascular Anesthesiologists, San Antonio, Texas, 5-S May 1991. Richmond, Virginia: Society of Cardiovascular Anesthesiologists, 1991.

SIR,-As Dr Beverly J Hunt and Professor Magdi Yacoub discuss in their editorial,' aprotinin reduces blood loss after cardiac surgery. We take issue, however, with some of their conclusions on mode of action.

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Urethral stricture after cardiac surgery.

infection rises the number of doctors infected during their clinical duties will also rise. Despite this doctors have treated and will, I hope, contin...
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