TRENDS in Parasitology Vol.17 No.3 March 2001

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Screening for Leishmania

Leishmaniasis CD-ROM

by The Wellcome Trust, CABI Publishing,2000. £120/US$195 Institutional; £30/US$55Student/Individual. ISBN 0 85 199370 2

The Leishmaniasis CD-ROM is one of aseries produced by The Wellcome Trust andCAB International, under the banner of‘Topics in International Health’. They areintended for use as an educational resourcein tropical and international health.According to the User Guide, they are aimedat medical and life science students,teachers, healthcare professionals,academics and researchers, which is a prettycomprehensive list. At first I was scepticalthat such a product might be of use to all thisdiverse group, but on closer inspection foundthis to be a reasonable claim.

Installation was straightforward andshould run on any PC of recent vintage(Pentium processor recommended, withWindows 95, or a more-recent operatingsystem). The contents are easy to navigate,using a mouse for most commands. Thevarious options and commands on eachscreen were largely self-evident andavailable via the usual drop-down menus orclicking on a button, and there was littleneed to resort to reading the instructions.The content is divided into two mainsections: a series of tutorials and an imagecollection. The glossary is accessible fromeither section.

Ten tutorials are available, ranging from‘Overview’ to those covering specific areas,for example, ‘Immunology’, ‘Epidemiology’,‘Diagnosis’. The overall content of thetutorials was strong on parasite biology andclinical features. However, there was littleon molecular biology, cell biology or

biochemistry. Presumably this was aconscious decision based on the targetaudience and because these areas changetoo rapidly. The main idea is to workthrough these tutorials one screen at a time,until the end is reached ~50 screens later.So, depending how long is spent exploring anindividual screen (e.g. 1–2 min), it takes30–60 min to complete an individualtutorial. There are also links to othertutorials along the way, so if you want to gooff on a tangent you can, and clicking on anunderlined word or phrase will open up adialogue box with more information. Thereare a smattering of animations that are fun,for example, a macrophage engulfing aparasite, and the general quality of thediagrams and pictures is excellent.Interspersed along the way are severalassessments (~5 per tutorial) where you areasked to match a statement with an imageor something similar, or answer a ‘True or

Book Review

placate taxpayers by appearing to dosomething.’ James Clauson, from a vector-control district in California, thought ofmosquito control more as an art than ascience and agreed about tolerance –‘California has a different threshold than,say, Florida’. Another entomologist fromCalifornia, Steve Schutz, added that in theSan Francisco Bay area, environmentalconsciousness is so high that ‘the meremention of the word “pesticide” causespeople to have adverse reactions.[so]…Wedo as little adulticiding as possible,preferring to concentrate on larval control’.Public perceptions and thresholds vary,sometimes even within a single town. Whenhe evaluated aerial spraying operations inNew Jersey ‘many thought the mosquitoeswere still bad and we weren’t sprayingenough, and the rest thought we weredestroying the environment and poisoningtheir children.’

Bloodmeal identification

In answer to a query, Bill Irby (GeorgiaSouthern University, GA, USA) gave a helpfulsummary and references. Briefly, identifyyour mosquito, grind it up in PBS, spin andthen test by immunoassay, either precipitin orELISA. For mammalian, reptilian oramphibian blood, antisera are usually madein rabbits or goats; for avian blood they aremade in chickens or pheasants. Anti-humanantiserum is available commercially (C.H.

Tempelis, Host-feeding patterns ofmosquitoes, with a review of advances inanalysis of blood meals by serology. J. Med.Entomol. 11, 635–653, 1975; R.K. Washinoand C.H.Tempelis, Mosquito host blood mealidentification: methodology and data analysis.Ann. Rev. Entomol. 28, 179–201, 1983.). Headded: ‘It perhaps is time for another review,covering applicable DNA techniques’. [Onecould see his point!]

However a few weeks later, andapparently coincidentally, Steven Ault fromBrazil asked is anyone actually preparingsuch a review? After a Medline search hehad found a dozen or so papers since a 1994review (S.M. Hill and J.M. Crampton, DNA-based methods for the identification ofinsect vectors. Ann. Trop. Med. Parasitol.88, 227–250, 1994), which also included asurvey of probes then available foridentifying the vectors and disease-causingorganisms they transmit. The papers,written by forensic scientists andentomologists, described work usingcytochrome B, mitochondrial DNA and PCRamplification of human DNA from differentindividuals [e.g. D.A. Boakye et al.,Identification of bloodmeals inhaematophagous Diptera by cytochrome Bheteroduplex analysis. Med.Vet. Entomol.13, 282–287, 1999; W.D. Lord et al.,Isolation, amplification, and sequencing ofhuman mitochondrial DNA obtained fromhuman crab louse, Pthirus pubis (L.), blood

meals. J. Forensic Sci. 43, 1097–1100, 1998;J.C. Koella et al., The malaria parasite,Plasmodium falciparum, increases thefrequency of multiple feeding of its mosquitovector, Anopheles gambiae. Proc. R. Soc.London B Biol. Sci. 265, 763–768, 1998; E. Chow-Shaffer et al., Laboratory and fieldevaluation of polymerase chain reaction-based forensic DNA profiling for use inidentification of human blood meal sourcesof Aedes aegypti (Diptera: Culicidae). J. Med. Entomol. 37, 492–502, 2000). Rob Anderson (Simon Fraser University,Canada) confessed that when askedrecently for ideas for the Annual Review ofEntomology the subject had crossed hismind, but he had not suggested it because itmight be thought self-serving as it is hismajor interest.

007 wants information...

The current author of the James Bond 007novels, employed by the Ian Fleming estate,wanted answers to some questions as he is‘playing with the idea of having the baddiesbreed deadly mosquitos and ship them todifferent parts of the world.’ Nothing morewas said. So wait and see!

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ParaSite was compiled from theInternet by Janice Taverne

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False’ question. Most of these are fairlysimple, but there are a few that require a bitof thought. I think they are a good feature,because otherwise it is too easy just to flickthrough the screens without necessarilytaking the information on board.

Each tutorial has been reviewed byexperts who are credited at the beginning.The reviewers are all well respected withinthe field, and they seem to have done a goodjob. I did not find any significant factualerrors. There are a few statements thatcould be the subject of some discussion andalternative opinions, but nothing verycontentious. If you want to get into theconventional literature for more informationthen clicking on ‘References’ will bring upexactly that. The references cited were up to1998 and, therefore, still current, and weremainly review articles rather than primaryliterature. These should hold their value forseveral years yet, because the topics coveredare in the main the important basics of thesubject, rather than trying to describe eventsat the cutting edge of research (which is notthe point anyway).

From the tutorial screen a notepad can bebrought up, where notes can be made andstored as you go along, which is a good ideafor students. Not surprisingly, you cannotprint out the contents of the tutorials tomake a hard copy. The individual tutorialsare also searchable via the ‘Find’ button,from where you can jump to the relevantsection. If you get stuck on a word, the‘Glossary’ is a helpful feature. For example, I found it useful with some of the medicalterms that I was less familiar with. I did notfind any technical terms in the tutorials thatwere not covered in the ‘Glossary’.

The image collection contains 834 picturesor diagrams, each of which is accompanied bya concise description. Many of these imagesare also used in the tutorials. The images areordered in sets relating to a common theme,for example, pictures of sandflies are togetherin one set and cutaneous leishmaniasis inanother and so on. The whole image collectionor a set can be browsed through individually,but they are mainly intended to be accessedusing the searching tools. There are two waysof doing this, first searching from a set ofprovided keywords, or second by performing atext search in which you type in your ownsearch term. The text search can be refinedfurther using multiple terms and booleanoperators. Once images have been found theycan be viewed in different ways: full screen,normal or gallery, in decreasing order of size.The gallery option allows you to look at

neighbouring images in the set. Images canalso be pasted onto the ‘photodesk’ so thatdifferent images can be easily compared side-by-side. The most useful feature is that theseimages can be printed out. The quality of theresulting hardcopy was very good in mostcases and an excellent resource for teachingand revision (subject to copyrightrestrictions).

In conclusion, I think this is a good buyfor any institution with a serious interest intropical medicine or parasitology, andshould be of value for several years before itis in need of updating. Students will find it auseful learning resource as will thosecharged with teaching them. Individualacademics with an interest in leishmaniasisshould consider making a purchase, and myown graduate students have found itbeneficial. I found it interesting, easy to useand learned a few things myself.

Paul Bates

Liverpool School of Tropical Medicine,Pembroke Place, Liverpool UK L3 5QA.e-mail: pbates@liv.ac.uk

Maps and epidemics

Remote Sensing and Geographical

Information Systems in Epidemiology

edited by S.I. Hay, S.E. Randolph and D.J. Rogers, Academic Press, 2000. £46.95/$69.95(pbk) (viii + 375 pages) ISBN 0 12 333560 4

Some 40 years on from the launch of Sputnik 1 in 1957, earth-orbiting satellitesare commonplace, relaying images of theearth in multiple hues representingvegetation or temperature that are familiareven to schoolchildren. Few of us, however,really understand their meaning or how thesedata might be interpreted or the informationapplied. Although there have beentantalizing glimpses of the developing fieldsof global imaging, remote sensing (RS) andgeographical information systems (GIS) andtheir potential applications in epidemiologyand public health at conferences over the pastten years, the science has remained largelyinaccessible to all but the expert. Thus, a bookthat provides some explanation of the rangeof knowledge, and its uses, is most welcome.

Clearly, all the contributors to this bookare enthusiasts for the methodology, andthis is apparent in many of the chapterswhere difficult concepts for the non-adeptare made accessible. By the end of the book,

the reader will have an understanding of thecontributions possible from differentsystems, and know their NOAAs (NationalOceanic and Atmosphere Administration)from their SPOTs (Satellite pourl’Observation de la Terre), and the differentsensors that these carry. Furthermore,much of the analytical approach is madeunderstandable, although the detailremains the domain of the specialist. Whatquickly becomes apparent is that this is arapdily advancing field, with much of thepublished literature being very recent – over80% of cited material on RS comes from thepast decade – while the linking epidemiologyis from earlier times. Four chapters aredevoted to the application of RS and GIS tofour very different areas of parasitology –trypanosomiasis, malaria, tick-bornediseases and helminths, or rather to how RSand GIS can be used to better understandthe dynamics of environment, vector, hostand disease. The chapters show (withexcellent colour plates) how different RSapproaches can be combined to provide amore coherent picture, and how these mightthen be interpreted through ground-basedstudies of vector behaviour and distributionand through studies of human or animaldisease. Each chapter will be of interest tothe specialist and generalist alike, providingboth new insights and large amounts ofsource material in these areas.

It has to be recognized that this is adeveloping science and all the authors freelyacknowledge the problems and failings ofcurrent knowledge. One wonders, therefore,what a similar book, written in perhaps 20years’ time, will be able to tell us? Theclosing chapters begin to look to at futureapplications of GIS (e.g. for diseaseprediction and management) and thepotential contribution of new RS systemsthat are being deployed now or that areplanned for the future. To extend knowledgerequires education, and it is to be hoped thatthose who read this book will become asenthusiastic as the authors are and beencouraged to explore further. Within itscovers, the authors have thoughtfullyprovided links to other, much larger, sourcesof information and training available toanyone with some time and access to theInternet. This reader has certainly beenencouraged to do so!

John Horton

SB Tropicals, SmithKline Beecham, SB House, Great West Road, Brentford, UK TW8 9BD. e-mail: john.horton@sb.com

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