Parasitology Today, rot. 9, no. 9, 1993 345

Molecular and Cell Biology of Opportunistic Infections

in AIDS

edited by Steve Myint and Alan Cann, Chapman & Hall, 1993. £40.00

(283 pages) ISBN 0 412 45330 4

This book, part of the 'Molecular and Cell Biology of Human Diseases' series, is most welcome as it bridges the com- plementary disciplines of molecular and cell biology, disease pathogenesis and clinical medicine. The organisms dis- cussed include most of the major opportunistic infections (OIs) that afflict HIV-positive people but, sensibly, not the biology of HIV I and HIV-2, which are covered in so many other texts. The editors apologize for the absence of discussion of Cryptococcus neofon roans because too little is known of its basic biology. They also worried about the propriety of including Salmonella and other Gram-negative rods, but they need not have: not only are such infections AIDS-defining diseases, but they are particularly frequent in Africa where (globally) most HIV-positive patients live. The discussion on the pathogenesis of these bacteria is excel- lent. Moreover, the major OI associ- ated with HIV disease in Africa, ie. tuberculosis, is well covered in the chapter on mycobacteria.

After an initial clinical overview of HIV-associated OIs, organized by organ systems, and a section on molecular biology in the diagnosis of infection, each chapter follows a similar format. Taxonomy, genetic structure, mechan- isms of invasion and survival or latency, pathogenesis of disease, diagnosis, and molecular aspects of chemotherapy are detailed. The authors (most of whom work in the UK) have been encour- aged to be exhaustive in their refer- ence lists, and several 1992 publications are mentioned. In addition to myco- bacteria and Gram-negative rods, there are chapters on Entamoeba, the coc- cidians Cryptospondium and Isospora, Toxoplasma, Pneumocystis, Candida and all the herpes viruses.

The polymerase chain reaction (PCR) is assuming increasing promi- nence in the diagnosis of HIV-associ- ated OIs in the industrialized world (the even-newer ligase chain reaction is also introduced in the book). The prin- ciple is to obtain ever-earlier diagnoses of infections so that appropriate ther- apy can be started. With pneumo- cystosis, PCR, because of its exquisite sensitivity, has also re-opened the question of the mode of infection since immunocompetent people show no trace of infection, which one might have expected if the pneumonia is a re-activation of latent infection.

The epidemiological use of PCR will also tell us more about patterns of OIs

with respect to HIV. Sadly, as the editors hint, little of this technology may be of much direct help to the millions of HIV-positive people and their overworked medical attendants in the developing world. The discussion of possible reciprocal effects of cytomegalovirus (CMV) and HIV in the progression of HIV disease could find future research material in the fact that, despite universal CMV seropositivity in Africa, HIV-positive patients there rarely suffer significant CMV disease.

Two chapters stand apart from the main canon of the book. A thorough account of the pathogenesis of Entamoeba histolytica (including recent material on the pathogenic vs non- pathogenic strain controversy) is wel- come, although that infection is not associated epidemiologically with HIV. Second, does Mycoplasma fermentans infection have anything to do with AIDS? The proponents of the theory that it is a major co-factor with HIV are given their head here. I won't give my view, but at least the investigative tools that can resolve the debate are now available. It is fortunate for science that the HIV pandemic did not start a decade or more earlier.

Sebastian Lucas Department of Histopathology UCL Medical School University Street London UK WCI E 6jJ

Principles of Acarology

by Gwilym O. Evans, Commonwealth Agricultural Bureau, (CAB) International, 1992. £65.00 (xviii + 563 pages) ISBN

0 85198 822 9

Mites and ticks are a tremendously diverse and important group of organ- isms, but few texts are devoted to them. Evans' book will therefore be an important addition to the bookshelves of many acarologists.

The main body of the text provides a broad summary of our current knowledge of mite physiology, behavior and morphology. Acarine integument is adequately described in the first chapter, albeit without much emphasis on chemistry. Unusual features are in- cluded such as the hardening of some

mite cuticles by calcification, and the synthesis of new cuticle in a single active instar as 'neosomy'. The second chapter discusses briefly muscle physi- ology and describes muscle insertions and mite segmentation as well as cov- ering glands, pores and cheatotaxy.

The nervous system, neurosecretion, sensory structures and circulation are included in a single chapter. This prob- ably reflects a gap in our knowledge in these areas. The literature cited with regard to neurotransmitters (only two papers) also reflects the need for more research. Studies have sug- gested the presence of neurosecre- tions and their effect on mite physiol- ogy but no compounds have been identified.

A chapter is devoted to the wide variety of respiratory structures and systems.

About one quarter of the book is dedicated to mouth parts, feeding and digestion. Mites have adapted to a wide variety of habitats and food sources, and this is reflected in the variety of mouth parts and digestive systems. However, our knowledge is scanty about the chemistry of digestion or about details of the digestive systems of most mites.

Chapter 8 covers the excretory system and water balance in the Acari. The author discusses excretory prod- ucts pointing out that, for most mites studied, guanine is the most common and excretory tubules exist, termed 'Malpighian' as in insects, but of differ- ent embryonic origin than those of insects. The chapter also includes descriptions of special water-balance systems: coxal glands, salivary glands in some mites, genital papillae,