Chemoprophylaxis and Chemotherapy

BRITISH MEDICAL JOURNAL 10 APRIL 1971 95 prepared in animals against human serum and labelled with a less, a laboratory which is regularly doing these tests, and fluorescent dye, usually fluorescein isothiocyanate, is applied. After which has established its own reproducible standards, can say further incubation and washings the film is examined under an with certainty whether an individual has been infected with ultraviolet fluorescence microscope. If antibodies were present in malaria in the fairly recent past, be able to Br Med J: first published as 10.1136/bmj.2.5753.95 on 10 April 1971. Downloaded from the serum they will have adhered to the parasites and the labelled and may identify antihuman serum will then have adhered to these, which will be the parasite, be more precise about the time, and indicate shown by their fluorescence. If there is no antibody in the serum whether active infection is possibly still present. there will be no fluorescence. The antibody in sera can readily be The introduction of refinements, such as measuring the rel- titrated and, depending on the sensitivity of the parasites used as ative amounts of antibody in the IgG, IgM, and IgA antigen, very high titres may be obtained. The antibodies detected immunoglobulin classes may give greater precision in the by this test are not necessarily immunologically-active neutralizing future.29 3 In clinical practice the test is therefore of value in antibodies; in fact, only a very small proportion of them probably retrospective diagnosis-for example, in a person who has are. been exposed to malaria, has suffered a febrile illness, but in When using this reaction considerable antigenic overlap is found among the four different human malaria parasites, and between whom antimalaria treatment has made conventional para- these and simian parasites. For detecting antibodies in human sitological diagnosis impossible. It has also been used in iden- malaria simian parasites are therefore often used, but for maximum tifying the responsible donors in cases of transfusion malaria, sensitivity it is certainly better to use human parasites. Though P in whom the parasitaemia may be low and intermittent. falciparum cross reacts with the other human parasites, it has The serological picture in those who have been repeatedly been claimed that in single infections the highest serum titre is exposed to malaria, such as those living in highly endemic found by using the homologous parasite as antigen.26 Failing areas, is far more difficult to interpret on an individual basis, human patients, parasites can be obtained only by. infecting though the test is proving of value in epidemiological studies. splenectomized chimpanzees or Aotus trivirgatus monkeys. For this reason the test is done in only a few specialized laboratories. Tests can be done using thin films of parasites,27 but isensitivity is Reference Laboratories probably increased by employing unfixed thick films.2 It is only recently that steps have been taken to attempt -Blood films for the diagnosis of malaria should be sent to some standardization of the indirect fluorescent antibody test, the nearest competent laboratory for examination. For confir- in terms of the sensitivity of the different antigens and details mation of the diagnosis, films may be sent to: The Malaria of technique, so that comparison of results from different Reference Laboratory, Horton Hospital, Epsom, Surrey; The laboratories is difficult. However, sufficient observations have Hospital 'for Tropical Diseases, 4 St. Pancras Way, London been made on man to allow some generalizations to be given. N.W.l.; Dept. of Parasitology, Liverpool School of Tropical Following single infections antibodies are usually detectable Medicine, Pembroke Place, Liverpool 4; Tropical Diseases after about a week, rise to a maximum titre after several Unit, Eastern General Hospital, Edinburgh 6. months, and then slowly decline, but may persist for years. Sera for testing for malaria antibodies may be sent to: Ross As well as the sensitivity of the test these variables depend Institute, London School of Hygiene and Tropical Medicine, on the amount of antigenic stimulus, which is related to the Gower Street, London WC1E 7HT; The Hospital for Tropical species of the infecting parasite, to the occurrence of relapses, Diseases, London. (a minimum volume of 0.5 ml of clean and to how much and how soon drugs were given. Neverthe- serum is required, sent by first-class mail). http://www.bmj.com/

Chemoprophylaxis and Chemotherapy

W. PETERS on 23 September 2021 by guest. Protected copyright.

British Medical_Journal, 1971, 2, 95-98 '60s,3 and over 140,000 compounds have been screened in the United States army programme during the last seven Man may be infected by four species of Plasmodium. Infection years. with P. vivax, P. ovale, or P. malariae is readily prevented and Though the current concepts of antimalarial prophylaxis the treatment of acute attacks with these parasites, once the and the treatment of the nonimmune individual have changed diagnosis is made, presents no problems. P. falciparum, on little from those of 15 years ago,37 the prevention and man- the other hand, may produce a more severe illness and agement of drug-resistant falciparum malaria are new aspects complications that necessitate the management of the patient of the present situation. as a medical emergency. Furthermore, in certain parts of Brazil, Colombia, Panama, Thailand, Laos, Cambodia, Viet- nam, Western Malaysia, Singapore, or the Philippines indi- viduals may become infected with strains of this parasite that Individual Prophylaxis exhibit a reduced response to one or more of the synthetic antimalarial drugs3132 (and in rare cases even to quinine33). Proguanil (Paludrine) and pyrimethamine (Daraprim) are Drug resistance has been the major stimulus for the large excellent casual prophylactics against P. falciparum and good volume of research that has been undertaken during the suppressive drugs against the other three species. Both com- pounds (also referred to as "antifols") interfere with the para- sites' metabolism by binding to their dihydrofolate reductase, which has a much stronger affinity for these drugs than the corresponding enzymes of the mammalian host.u Liverpool School of Tropical Medicine, Liverpool L3 SQA Trimethoprim, another antifol, is relatively less effective than W. PETERS, M.D., D.T.M.&H., Walter Myers Professor of Parasitology pyrimethamine in binding the parasite enzyme but has an ex- ceptionally high affinity for that of certain bacteria. 96 BRITISH MEDICAL JOURNAL 10 APRIL 1971

Chlorproguanil (Lapudrine) is a proguanil analogue that is Treatment of Uncomplicated Attack administered weekly instead of daily (see Table for dosages). the species involved, the acute attack The 4-aminoquinolines-that is, chloroquine and Irrespective of parasite

to prompt treatment with Br Med J: first published as 10.1136/bmj.2.5753.95 on 10 April 1971. Downloaded from amodiaquine-inhibit the development of asexual erythrocytic of malaria usually responds chloroquine or amodiaquine given by mouth with appropriate forms of the parasites by interfering with the processes by within supportive therapy, including bed rest, fluid replacement, and which the organisms digest the host cell haemoglobin maintenance of the electrolyte balance. An initial loading which they live.39 They thus provide good clinical protection dose of 600 mg chloroquine base is followed in six hours by a by suppressing parasitaemia but do not act as casual further 300 mg and this is followed by two further doses, prophylactics. Any of the compounds so far mentioned should each of 300 mg, on the second and third days of treatment. If produce a suppressive cure of falciparum infection if started amodiaquine is preferred, 600 mg on the first day should be one week before first exposure and continued for at least one followed by 400 mg on each of the second and third days. month after the last exposure to infection. The normal Though either regimen should ensure a radical cure of fal- prophylactic dose of chloroquine is 300 mg and of ciparum malaria, it may be necessary to continue the treat- amodiaquine 400 mg, taken as a single dose once weekly after a meal, These doses, like most in this article, are for a "stan- ment for a further day or two until fever and parasitaemia dard" adult weighing 70 kg (150 lb) and refer to base content have completely subsided, after which it is advisable to take a unless otherwise stated. The treatment of malaria in children further weekly dose for an additional month. has been reviewed in the B.M.7. by Gilles." Side effects of Infection with P. vivax, P. ovale, or P. malariae is likely to the aminoquinoline are uncommon in adults. One of the relapse, since the 4-aminoquinolines do not prevent relapses in antifols may be preferred for children who do not always any of these species. Therefore, though relapsing infections or accept the intensely bitter taste of chloroquine will be suppressed provided the patient continues to take his amodiaquine. (Basoquin, a tasteless preparation for children, is suppressive drug, it is necessary once he leaves the malaria available in certain countries. It is amodiaquine base.) zone to administer in addition the 8-aminoquinoline, Although some authorities recommend taking 100 mg chloroquine daily (for six days in each week) in conditions primaquine, for 14 days at a twice-daily dose of 7.5 mg (1 where they are exposed to a particularly high risk of infec- tablet). Patients infected with P. vivax in New Guinea may tion,40 I believe that this is an unnecessarily high dose for require 22-5 mg daily instead of the usual 15 mg"3 most adults. The highest transmission rates of P. falciparum This regimen may induce gastrointestinal symptoms. are found today in parts of tropical Africa and New Guinea. Individuals with a deficiency of glucose-6-phosphate In both these regions this parasite appears to be very sensi- dehydrogenase or certain other hereditary enzyme defects tive to 4-aminoquinolines.324 may develop transient methaemoglobinaemia and haemolytic oral of antifols with Various potentiating combinations anaemia while taking this quantity of primaquine. In a few or with dapsone are currently being promoted. sulphonamides cases it may be preferable simply to allow the infection to At the time of writing relatively few data are available to burn itself out over the next year or two, giving chloroquine indicate how effective these combinations are for prophylaxis to suppress parasitaemia during overt clinical attacks while in nonimmune individuals.42 They cannot in the absence of further evidence be generally recommended at present for allowing immunity to develop. Unfortunately no antirelapse prophylaxis in nonimmunes and, indeed, are not necessary drug is yet available that does not also produce side effects in http://www.bmj.com/ for this purpose except where drug resistance is confirmed.4" a small proportion of cases.

Compounds and Combinations Available for Prophylaxis and Treatment of Malaria. (Doses suggested for Non-immune Patients)

Non-proprietary Name FormulationBase Content*and Manufacturers ProprietaryName Adult DosetProphylactic Adult DoseTreatment CmetComments Single Drugs on 23 September 2021 by guest. Protected copyright. Proguanil HC1 .. .. Tab. 100 mg Imperial Chemical Industries Paludrine 100-200 mg daily _ Not advised if local Chlorproguanil HC1 ..Tab. 20 mg Imperial Chemical Industries Lapudrine 20 mg once weekly _ strains resistant to this Pyrimethamine Tab. 25 mg Burroughs Wellcome Daraprim 25 mg once weekly (see text) group Chloroquine salt (phosphate Tabs. 100, 150, or Various Various 300 mg once weekly 600 mg immedi- or sulphate) .. 300 mg or 100 mg daily for ately; 300 mg after 6 days a week 6 hours; 300 mg on Not to be used alone 2nd and 3rd days for treatment of multi- Chloroquine phosphate .. 5hsolution, 40 mg/ml Imperial Chemical Industries Avloclor _ (see text) ple-drug-resistant P. Amodiaquine HCI .. i Tab. 200 mg I Parke, Davis Camoquine 400 mg once weekly 600 mg stat; 400 mg falciparum infection Amodiaquine base .. Tabs. 150mg suspen- Parke, Davis Basoquin* 450-600 mg once I sion 150 mg/ml weekly Quinine sulphate or dihydro- Tabs. 540 mg. Solu- Various - _ (see text) Only advised in treat- chloride .. tion 60 mg/ml (salt) ment of serious P. falciparum infection, especially if multiple- drug-resistant Primaquine diphosphate .. Tab. 7-5 mg Various Various _ (see text) Anti-relapse treatment malariae Cycloguanil embonate .. Oily suspension 140 Parke, Davis Camolartt 2-5 ml deep intra- - Follow detailed recom- mg/ml muscular injection mendations of manu- once every 3-4 months facturer Combination Drugs Pyrimethamine Tabs. 12-5 mg Burroughs Wellcome Maloprim 2 tabs. 1 week before _ Paediatric dose still + dapsone .. .. + 100 mg exposure than 1 tab. under review by manu- once weekly facturer Pyrimethamine Tabs. 25 mg Roche Fansidar _ 2-3 tabs. as a single Not promoted by + sulphadoxine .. + 500 mg dose manufacturer for pro- phylaxis Pyrimethamine Tabs. 10 mg Burroughs Wellcome Daraclor 1-2 tabs. once weekly 2 tabs. three times + chloroquine sulphate .. + 150 mg daily on 1st day; 2 tabs. on 2nd and 3rd days

*Various brands of a preparation may contain different quantities of salt in apparently the same size tablet, but the label should specify the actual base content to avoid confusion. tSee references ' ° 7or manufacturers' recommendations for paediatric dosage. Orally administered antimalarials are generally well tolerated by children, but doses may have to be repeated if the drug is vomited within an hour of ingestion. Young's formula is a useful guide to dosage if in doubt.3 ttNot marketed in the United Kingdom but available in certain other countries. BRIZTISH MEDICAL JOURNAL 10 APRIL 1971 97 Treatnent of Seriously III Patient deteriorate when treated with chloroquine. If the immediate response is normal asexual parasites may recrudesce and Most fatal cases of malaria are caused by P. falciparum and fever reappear at any time from a few days to about two are due to the misdiagnosis of the nature of the illness47 The months (rarely longer) after the completion of treatment. If Br Med J: first published as 10.1136/bmj.2.5753.95 on 10 April 1971. Downloaded from production of high levels of parasitaemia, of multiple the condition of the patient is not serious and he can readily microemboli, and sludging owing to the segregation of parasi- support oral medication he may be given one of the following tised erythrocytes in the deep capillary circulation are among combinations together with the standard course of chloro- the factors that lead to serious complications in this disease. quinet (1.5 g base over a period of three days). These complications commonly present as cerebral malaria. Pyrimethamine 50 mg + sulphadoxine 1,000 mg (Fan- Renal failure with or without the severe haemoglobinuria of sidar).51 blackwater fever may develop alone or may accompany cere- Pyrimethoprim 500 mg + sulphalene 1,000 mg t. bral malaria and this is occasionally associated also with Trimethoprim 500 mg + sulphalene SLZ mw t5. acute pulmonary oedema. Hypotension following peripheral They are given in a single or divided doses together with vascular collapse, defects of the microcirculation of the re- the chloroquine on the first day of therapy. spective organs, electrolyte and fluid imbalance due to severe In the United States quinine sulphate (USP) is preferred to vomiting and sweating, and occasionally disseminated intra- chloroquine in this indication. Up to 650 mg salt (10 grains) vascular coagulation may all contribute to the grave clinical are given " three times daily for 10 to 14 days. In addition to picture " especially in cases that are diagnosed late in the quinine 50 mg of pyrimethamine are administered daily for infection. the first three days.5' A daily dose of 25 mg dapsone may also Antiparasitic treatment must be administered without delay be given from the beginning of therapy and continued for a in every case and should be begun parenterally. Doses of 200- further month to exclude recrudescences.5' Not all patients 300 mg chloroquine base (as a 5 % solution of the salt*) may are able to tolerate so much quinine. While quinine therapy be given intramuscularly and repeated after six hours if nec- alone will produce a good initial clinical response in most essary. Alternatively up to 650 mg quinine dihydrochloride (though not all) cases, chloroquine cannot be relied on to do (10 grains) may be administered in a slow intravenous drip so and its use alone for such patients is contraindicated. (500 ml of normal saline, glucose saline, or plasma in 15 to 20 The problem of which drug to recommend for prophylaxis minutes) and this dose may be repeated up to three times in in countries where strains of P. falciparum are known to be the first 24 hours if indicated. Since quinine is eliminated resistant not only to antifols but also to 4-aminoquinolines is more slowly than normal when renal function is disturbed no difficult to answer at present.32"4 5 While proguanil or more than 650 mg (10 mg/kg body weight) should be given pyrimethamine, perhaps in double the usual dosage, may still in a 24-hour period unless the quinine plasma level can be give good protection (since the pre-erythrocytic stages are monitored. It should not be allowed to exceed 10 mg/litre, more responsive to their action than the blood forms), they above which symptoms ("cinchonism") and signs (electro- cannot be completely relied on. Chloroquine will protect cardiographic changes) of toxicity appear.'6 Oral therapy against P. vivax, ovale, or malariae as well as against most should replace parenteral therapy with either drug as soon as strains of P. falciparum. Even increased dosage, however, will practicable. If the patient is thought to have been infected in not always prevent infection with resistant strains. It is a country where chloroquine-resistant P. falciparum is present, against these that one of the antifol combinations may well or if there is any doubt about this, intravenous quinine must prove the most useful prophylactic available at the present be used. time. (See Table for Maloprim. For other combinations half http://www.bmj.com/ It is essential to institute some form of dialysis'6 to correct to one single treatment dose may be given once weekly.) Care uraemia and electrolyte fluid imbalance with a minimum of must be taken, however, not to recommend these to people delay. Blood transfusion may be called for if there is severe with known sensitivity to sulphonamides. Current clinical anaemia. The judicious intravenous administration of cor- trials indicate that the diformyl derivative of dapsone54 may tisone or an equivalent corticosteroid may be beneficial in prove to be a useful prophylactic against chloroquine-resistant patients with malignant tertian malaria, in particular when strains. cerebral or pulmonary symptoms or blackwater fever are present (4-6 mg of dexamethasone every four to six hours on 23 September 2021 by guest. Protected copyright. has proved useful in some cases"5). Convulsions may be con- trolled by sodium diphenylhydantoin (400 mg daily) or other Communities in Endemic Areas suitable anticonvulsant drug. The cautious use of heparin may be of value if there is clear evidence of disseminated For the treatment of indigenous patients of malaria endemic intravascular coagulation but this appears to be a rare areas lower doses may usually be given.37 Falkiparum malaria, complication in man.45 both due to drug-sensitive and to drug-resistant strains, responds well to the antifol combinations. Recent data from clinical trials in the Gambia indicate that doses of pyrimethamine of about one-tenth of those normally consid- Drug-resistant Falciparum Malaria ered necessary in combination with sulphadoxine or dapsone rapidly reduce parasitaemia and fever in infants and children How malaria parasites become resistant to chloroquine is still with acute malarial symptoms.55 not known with certainty, though two general hypotheses (probably in fact complementary to each other) have been proposed. One suggests that in resistant parasites there is a *Avloclor Injection Solution contains 40 mg chloroquine base, as phos- phate, per ml. Single doses should not exceed 5 mg/kg body weight deficiency of chloroquine-binding sites, which normally con- intramuscularly and the total dose 7.5 mg/kg in a 24-hour period. centrate the drug from the plasma."7 The second indicates tThe prime antiparasitic role in patients infected with these resistant that resistant plasmodia are able to activate pathways of strains falls upon the antifol combination. The chloroquine will prob- aerobic glycolysis and amino-acid synthesis that are, in drug- ably facilitate the rapid removal of parasitaemia and, by virtue of its sensitive parasites, opened up only during the invertebrate general pharmacological properties, help the patient's rapid recovery. Preliminary reports suggest that amodiaquine may be relatively more phases of the life cycle.39 The modes of antimalarial drug active against some strains of multiple-drug-resistant P. falciparum than action and drug resistance have been reviewed recently at chloroquine.49 length. 1s *The manufacturcrs of sulphalene recommend that 1,000 mg should be People infected with P. falciparum in the countries listed given in either of thcse combinations. Children should receive 20-25 mg/kg together with 1 mg/kg pyrimethamine or 12.5 mg/kg trime- above may respond more slowly, fail to improve at all, or thoprim. 98 BRITISH MEDICAL JOURNAL 10 APRIL 1971 For mass chemoprophylaxis also, these and the other 19 Field, J. W., The Microscopic Diagnosis of Human Malaria, Part I. Study No. 23 from the Institute for Medical Research, Federation of types of combinations show in the Table have proved effec- Malaya. Kuala Lumpur, Government Press, 1948. tive in drug trials in several parts o£ Africa and else- 20 Field, J. W., and Shute, P. G., The Microscopic Diagnosis of Human Malaria, Part II. Study No. 24 from the Institute for Medical Research, Br Med J: first published as 10.1136/bmj.2.5753.95 on 10 April 1971. Downloaded from where.40 48 55 56 The danger of producing drug-resistant strains Federation of Malaya. Kuala Lumpur, Government Press, 1956. not only of malaria but also of certain bacteria (especially 21 Brown, I. N., Advances in Immunology, 1969, 11, 267. be weighed in the bal- 22 Voller, A., and Schindler, R., Bulletin of the World Health Organization, Neisseria meningitidis) must however 1967, 37, 675. ance before making any blanket recommendations for their 23 Wilson, R. J. M., McGregor, I. A., Hall, P., Williams, K., and large-scale use.40 42 5 While this precaution applies equally to Bartholomew, R., Lancet, 1969, 2, 201. 24 Mathews, H. M., Fisher, G. U., and Kagan, I. G., American Journal of the injectable depot prophylactic cycloguanil embonate Tropical Medicine and Hygiene, 1970, 19, 581. (Camolar), this has the added disadvantage that in field use it 25 Tobie, J. E., and Coatney, G. R., Experimental Parasitology, 1961, 11, the 128. may cause sterile abcesses in a significant proportion of 26 Wilson, M., Sulzer, A. J., and Runcik, K., American Journal of Tropical recipients-58 Medicine and Hygiene, 1970, 19, 401. Though the perfect antimalarial59 is not yet with us, some 27 Voller, A., Bulletin of the World Health Organization, 1964, 30, 343. 28 Sulzer, A. J., Wilson, M., and Hall, E. C., American Journal of Tropical first-class drugs and drug combinations are available. The 4- Medicine and Hygiene, 1969, 18, 199. aminoquinolines are still outstanding for the treatment of 29 Collins, W. E., and Skinner, J. C., VIII International Congress on Tropical Medicine and Malaria, Teheran. Abstracts and Reviews, p. acute malaria, with the important exceptions discussed above, 1424. 1968. and both they and the antifols are excellent individual 30 Targett, G. A. T., Clinical and Experimental Immunology, 1970, 7, 501. with the above 31 World Health Organization. Technical Report Series, No. 375. 1967. prophylactics. If they are judiciously applied 32 Peters, W., Transactions of the Royal Society of Tropical Medicine and recommendations as a guide there should be no great dif- Hygiene, 1969, 63, 25. ficulty in protecting most patients from malaria nor in treat- 3 Clyde, D. F., Miller, R. M., DuPont, H. L., and Hornick, R. B., Journal of the American Medical Association, 1970, 213, 2041. ing most of them if they do become infected, provided that 3 Sadun, E. H., and Osborne, H. S. (eds.) Military Medicine, 1966, 131, the diagnosis is made early and therapy begun promptly. For 847. 35 Sadun, E. H., and Moon, A. P. (eds.) Military Medicine, 1969, 134, 729. mass drug administration and for the prevention of drug- 36 Tigertt, W. D., Annals of Internal Medicine, 1969, 70, 150. resistant malaria new and better drugs are still badly needed. 3 Covell, Sir G., Coatney, G. R., Field, J. W., and Jaswant Singh, Chemo- therapy of Malaria, World Health Organization, Geneva, 1955. 38 Ferone, R., Burchall, J. J., and Hitchings, G. H., Molecular Pharmacology, 1969, 5, 49. 39 Howells, R. E., Peters, W., Homewood, C. A., and Warhurst, D. C., Nature, 1970, 228, 625. 40 Bruce-Chwatt, L. J., Transactions of the Royal Society of Tropical References Medicine and Hygiene, 1970, 64, 776. 41 Martin, D. C., and Arnold, J. D., Transactions of the Royal Society of 1 World Health Organization, Official Records, No. 177, Geneva, 1969. Tropical Medicine and Hygiene, 1967, 61, 331. 2 Maegraith, B. G., Exotic Diseases in Practice, London, Heinemann, 1965. 42 Peters, W., East African Medical3Journal, 1971, in press. 3 Bruce-Chwatt, L. J., Transactions of the Royal Society of Tropical 43 Black, R. H., Australasian Annals of Medicine, 1958, 7, 259. Medicine and Hygiene, 1970, 64, 201. 4 Canfield, C. J., Bulletin of the New York Academy of Medicine, 1969, 45, 4 Dorolle, P., British Medical_Journal, 1968, 4, 789. 1043. 5 Organization for Economic Co-operation and Development. Tourism in 45 Neva, F. A., Sheagren, J. N., Shulman, N. R., and Canfield, C. J., O.E.C.D. Member Countries, Paris, 1968. Annals of Internal Medicine, 1970, 73, 295. 6 Ministry of Health. Communicable Diseases Contracted Outside Britain, 46 Canfield, C. J., Miller, L. H., Bartelloni, P. J., Eichler, P., and Barry, London, Ministry of Health, 1968. K. G., Archives of Internal Medicine, 1968, 122, 199. 7 Shute, P. G., and Maryon, M., British Medical Journal, 1969, 2, 781. 4 Fitch, C. D., Science, 1970, 169, 289. 8 Department of Health and Social Security. On the State of the Public 48 Peters, W., Chemotherapy and Drug Resistance in Malaria. Academic Press, New 1970. Health. Annual Report of the Chief Medical Officer for 1969. London, York, http://www.bmj.com/ H.M.S.O., 1970. 49 Rieckmann, K. H., Journal of the American Medical Association, 1971, in 9 Stevenson, D., Transactions of the Royal Society of Tropical Medicine and press. Hygiene, 1970, 64, 786. '0 Bartelloni, P. J., Sheehy, T. W., and Tigertt, W. D., Journal of the 10 Gilles, H. M., British Medical_Journal, 1966, 2, 1375. American Medical Association, 1967, 199, 173. 11 Bruce-Chwatt, L. J., Lancet, 1970, 2, 143. 51 Clyde, D. F., Current Therapy, 1970, p. 18. 12 Shute, P. G., personal communication. 522Sheehy, T. W., Reba, R. C., Neff, T. A., Gaintner, J. R., and Tigertt, 13 Fischer, G. U., Bulletin of the New York Academy of Medicine, 1969, 45, W. D., Archives of Internal Medicine, 1967, 119, 561. 1016. 5 Powell, R. D., and Tigertt, W. D., Annual Review of Medicine, 1968, 19, 14 Dike, A., Lancet, 1970, 2, 72. 81. 15 Shute, P. G., and Maryon, M. D., Laboratory Technique for the Study of 5 Clyde, D. F., Rebert, C. C., McCarthy, V. C., Dawkins, A. T., jnr., and Malaria, 2nd edn. London, Churchill, 1966. Cucinell, S. A., Military Medicine, 1970, 135, 527. 16 Maegraith, B. G., and Leithead, C. S., Clinical Methods in Tropical 15 Laing, A. B. G., Transactions of the Royal Society of Tropical Medicine on 23 September 2021 by guest. Protected copyright. Medicine. London, Cassell, 1962. and Hygiene, 1970, 64, 562. 17 Swartzwelder, J. C., Miller, J. H., Warren, L. G., and Abadie, S. H., in 56 Lucas, A. O., et al., Transactions of the Royal Society of Tropical Medicine Manual of Clinical Microbiology, chap. 49, eds. J. E. Blair, E. H. and Hygiene, 1969, 63, 216. Lennette, and J. P. Truant. Bethesda, American Society for Micro- 57 Schmidt, L. H., Annual Review of Microbiology, 1969, 23, 427. biology, 1970. 58 Clyde, D. F., Journal of Tropical Medicine and Hygiene, 1969, 72, 81. 1 Wilcox, A., Manual for the Microscopical Diagnosis of Human Malaria 59 Bruce-Chwatt, L. J., Transactions of the Royal Society of Tropical Washington, U.S. Government Printing Office, 1960. Medicine and Hygiene, 1965, 59, 105.