Conversely, but for the fact that the individual was excreting giardia, the incident might not have been discovered. This incident highlights a potential danger to public health from malicious interference with communal water supplies. The Badenoch committee recommends measures to improve bacteriological safety of drinking water at source. In view of the potential for deliberate contamination of water at any point in the
airborne fungal spores to the open container than to the sealed sachets. These findings confirm the observations of De Bock et al, show that other fungal species reside in pepper, and that this occurs frequently. Whether or not this contamiantion is a hazard for immunocompromised individuals is not known. Nevertheless, nosocomial aspergillosis is of considerable concern for the severely
distribution system, and in order to prevent recurrence of incidents
like that described here, we suggest there is a need for relevant authorities to protect supplies from interference.
In the absence of evidence on the significance of fungal contamination of pepper, it seems prudent for hospitals to serve pepper in sachets and to autoclave pepper taken into "life-island" laminar flow units, as suggested by De Bock and colleagues.
Lothian Health Board, Department of Public Health Medicine, Carlton House, Edinburgh EH7 5DG, UK
C. N. RAMSAY
1. Report of the group of experts on cryptospondium in water supplies. London: HM Stationery Office, 1990. 2 Jephcott AE, Begg NT, Baker IA. Outbreak of giardiasis associated with mains water in the United Kingdom. Lancet 1986; i: 730-32. 3 Craun GF. Waterbome giardiasis in the United States: a review. Am J Public Health
1979, 69: 817-19.
Lawrence conclude that "air travellers in transit through endemic malaria areas should be advised to take appropriate chemoprophylaxis no matter how slight their risk of expsoure". We believe that such advice should be given with great caution. Firstly, the risk of acquiring malaria in such situations is probably very low. Secondly, there are no prophylactic regimens that are 100% protective. Thirdly, there are no prophylactic regimens that are completely safe and free of side-effects. Chemoprophylaxis with mefloquine in areas with high levels of chloroquine resistance may be dangerous. In such situations chemoprophylaxis probably has no benefits. Moreover, because antimalarials must be taken for four weeks after return from endemic areas, compliance will probably be low. We advise travellers passing through malarious regions to take anti-mosquito measures. We recommend that if fever or other symptoms develop on their return, they should seek immediate medical attention and tell the doctor about their travels; the best way to avoid severe and complicated malaria is early diagnosis and
appropriate treatment. Doctors should remember the advice of the late Professor Maegraith, 27 years ago,1 to ask their patients: unde venis? (where
have you been?).
1. Maegraith BG
Gyssens I, Peetermans M, Nolard N. Aspergillus in pepper. Lancet 1989;
with monoclonal antibodies
SIR,-Dr Oswald and Dr Lawrence (June 23, p 1537) report a non-immune British woman who acquired malaria during the 1 h stop at Abidjan airport without leaving her aircraft seat. Oswald and
CAP Drassanes, Universidad Autonoma,
1 De Bock R,
Specificity of dystrophin analysis improved
Department of Microbiology, Imported Disease Unit,
SERGIO VARGAS WALTER T. HUGHES MARY ANNE GIANNINI
St Jude Children’s Research Hospital, Memphis, Tennessee 38101, USA
JOSE L. BADA JUAN CABEZOS JOSÉ L. FERNANDEZ-ROURE
SIR,-Analysis of dystrophin abnormalities in muscular dystrophy patients! and carriers2 by immunostaining and immunoblotting of muscle biopsy specimens has quickly become established as a valuable aid to differential diagnosis. Predictions from the dystrophin sequence suggest a rod-like structural protein on the inner face of the muscle membrane, consisting of a long central domain which separates an N-terminal actin-binding domain from a cysteine-rich domain and a Cterminal domain.3 Deletions or alterations affecting the cysteinerich and C-terminal domains seem to have the most severe pathological effects,4,5so it is very important to have antibodies that specifically recognise these regions of normal dystrophin. Unfortunately, polyclonal antisera raised against the C-terminal regions of dystrophin cross-react with an unidentified, even less abundant, protein of the same molecular size on immunoblots.6 Used on Duchenne patients who lack dystrophin, such antibodies could give a false impression of a normal-sized dystrophin present in reduced amounts, a situation associated with less severe forms of muscular dystrophy.! This problem can be overcome by the use of monoclonal antibodies. A cDNA fragment coding for the last 485 aminoacids (this includes part of the cysteine-rich region and all the C-terminal domain) was obtained by digestion with DraI and cloned into the expression plasmid pATH2. The recombinant fusion protein was
Unde venis? Lancet 1963; i: 401-04
SIR,-De Bock and colleagues1 reported contamination of dietary pepper with Aspergillus spp on their haematology unit. To determine the frequency of fungal contamination we cultured 102 pepper samples collected at St Jude Children’s Research Hospital, a paediatric oncology centre, during April, June, and July, 1990. These samples were taken from pepperpots or individual sachets within the hospital wards, lounge areas, and cafeteria. 11 of 40 samples (27-5%) from the pepperpots were contaminated with one or more species of fungus (Aspergillus 7, Fusarium 1, Curvularia 1, Scopulariopsis 1, Penicillium 3, and Nigrospora 1 spp). Of the 62 samples of packaged pepper 2 (3%) showed contamination
(Aspergillus 1, Cladosporium 1). Although the source of pepper for the two packages could have been different, the greater fungal contamination found in pepper from pots may be explained by easier
Fig 1-False positives in (a) due to cross-reacting protein in immunoblot test for dystrophin can be avoided (b) by use Qf monoclonal antibody.
Immunoblottlng of extracts of normal (N) and dystrophic (DYS) muscle was done as described,’ except that a sensitive biotin-avidin method (’Vectastam’, Vector Laboratories) was used to detect bound monoclonal antibody Identical muscle extracts were used in (a) and (b) and same amount of total protein was loaded in all lanes