The American Journal of Tropical Medicine and Hygiene - Volume 18, Issue 3, May 1969

I deeply appreciate the honor conferred on me by our president, Dr. William McD. Hammon, when he asked me to serve as chairman of the committee to select the Craig Lecturer for 1968. The committee included Dr. Frederik B. Bang and Dr. William C. Reeves, both of whom were far better qualified than I to serve as chairman.

You should know we proceeded systematically to survey the field and decide which subject was apposite for 1968. The theory we assumed was that once the right subject was chosen, the right man would immediately become obvious. The reverse is what happened.

In an exchange of correspondence a total of nine subjects were mentioned. Then in the effort to find the most appropriate one, I asked an elder statesman of the Society for his opinion. He answered, “Why don't you invite Dr. David J. Sencer, a member who lives in Atlanta and who has done the most in recent years for tropical medicine?

Not long ago, I received a telephone call from a physician in Cleveland, Ohio, who had been referred to NCDC by his local health department. He thought he had a patient who had South African tick typhus fever. I replied that I would not know the difference between South African tick typhus fever and tsutsugamushi fever. He promptly told me that they were very similar. The physician had been in the Navy in the South Pacific during World War II and had had opportunity to observe and manage tsutsugamushi fever. His patient had returned 10 days previously from a safari in Kenya and had developed lymphadenopathy, eschar, and fever.

If the Presidential Address of last year did not indicate to this group the shrinking nature of this world, certainly this story should. With today's transportation, with today's dispersion of people—military, Peace Corps, technicians, travelers—the “fortress mentality” that perpetuates stringent quarantine activities can no longer exist.

Anopheles albimanus mosquitoes transmitted blood-induced Plasmodium vivax infection from three night monkeys, Aotus trivirgatus, to three other night monkeys and to a Panamanian marmoset, Saguinus geoffroyi. Mosquito-transmissions of the malaria also were successful from one black spider monkey, Ateles fusciceps, to two other black spider monkeys. Prepatent periods ranged from 14 to 29 days and patent periods from 19 to 37 days. Plasmodium vivax in S. geoffroyi developed less than 10 parasites per cmm in contrast to maxima of 42,850 and 8,390 per cmm in A. trivirgatus and A. fusciceps on primary infection. Relapse occurred in one A. trivirgatus and in one A. fusciceps after subpatent intervals of 27 and 4 days. The relapse infections were patent for 29 and 24 days and reached maxima of 15,420 and 15,470 parasites per cmm. Mosquitoes were infected from feeding upon each A. trivirgatus and one A. fusciceps. This report of mosquito-transmissions of P. vivax infection to Panamanian primates appears to be the first of sporozoite-induced human malaria in monkeys.

A strain of Plasmodium malariae from a patient with congenital quartan malaria was isolated in a splenectomized night monkey, Aotus trivirgatus. After a prepatent period of 100 days, the parasitemia developed to a peak of 97,920 parasites per cmm of blood. The strain is being maintained in splenectomized and intact A. trivirgatus.

Small-bowel biopsy was performed in 20 soldiers acutely ill with falciparum malaria. Histopathologic examination revealed minimum vascular congestion and edema of the lamina propria. Xylose absorption was impaired in eight of 10 patients tested, the abnormal results ranging between 1.25 and 2.80 g per 5 hours after a 25-g dose. In contrast, lactose-tolerance tests were normal (blood-glucose elevation greater than 20 mg per 100 ml) in 11 of 12 patients tested with an oral dose of 1.5 g per kg of body weight. The histopathologic findings and impairment of xylose absorption suggest that there may be decreased splanchnic blood flow in this disease similar to that observed in simian-malaria models.

After infection with Plasmodium lophurae, the spleens and bursae of thymectomized chickens were significantly smaller than those of intact, infected birds. The mean ratio of bursa weight to body weight in female birds was significantly greater than the mean ratio of the males in both infected groups. Two basic types of follicular degeneration occurred in the bursa as a result of the infection, the first being a simple loss of cells from the medullary region, whereas the second led to the complete destruction of the follicle and its replacement by interfollicular connective tissue. During particularly severe infections, practically all bursal follicles degenerated. Lymphocytic depletion occurred in the spleen by day 2 of the infection, and lymphoid regeneration began by day 6. The reparative events in the spleen appeared to proceed as well in bursectomized as in normal birds. Although results from thymectomized birds were inconclusive, there was some indication that non-nodular lymphoid regeneration might be under thymic control. After infection, the amount of thymic medullary tissue increased at the expense of cortical tissue. In addition, cellular degenerative changes were noted in the medulla. Lymph nodules often appeared in the thymic medulla. The female thymectomized birds had earlier, depressed-peak parasitemia as compared with male thymectomized birds or sham-operated controls.

Clinical and blood surveys were made in four villages of Tutuila, American Samoa, in 1962 before and after treatment with diethylcarbamazine (DEC) in order to determine the current prevalence of filariasis, investigate continued transmission, assess the need for control, and evaluate dosages and schedules for drug administration. The microfilaria (mf) rate was 20.4%, the elephantiasis rate 3.4%, and no spontaneous decline of clinical or hematologic filariasis had apparently occurred during the previous 20 years. Therefore, mass treatment with DEC was recommended to a total dose of 72 mg per kg of body weight. This dose reduced the mf rate to 3.9% by the end of the first year, but, regardless of the schedule adopted for its administration, appeared insufficient for adequate control. However, because reductions of mf rate in two villages receiving identical regimens of DEC appeared proportional to their pretreatment level of mf infection, it was suggested that further treatment with DEC be administered to determine its subsequent effect upon mf rates and transmission.

Adhesion of white cells to microfilariae in vitro has been reported, but we found no record of cell adhesion to the cuticle of the larvae of Dracunculus medinensis. We noted adhesion of white cells to living and dead guinea-worm larvae in bleb fluid from four patients with guinea-worm disease, and in fluid aspirated from the joint cavities of 10 patients with acute guinea-worm arthritis. More cells were found adhering to larvae in lesions of long duration. No adhesion of white cells to living or dead larvae was found in fluids from hydrocele or in one case of microfilarial granuloma of the brain. This phenomenon is thought to be due to phagocytosis or to some other mechanism.

The successful removal by extracorporeal hemofiltration of adult parasites from patients affected with hepatosplenic disease caused by Schistosoma mansoni and Schistosoma japonicum stimulated the development of an operation for Schistosoma haematobium. Although based on similar principles, it is a simpler procedure resembling the catheterization used frequently in radiographic vascular visualization. In Iran, three male patients with active urinary schistosomiasis were selected for extracorporeal hemofiltration. The operations were performed and were technically successful; however, no worms were found in the filters. The failure to capture the worms, which may be attributed to various factors, has served as a stimulus for further studies on the location and physiologic response of the parasite.

Animal-derived hydatid-fluid antigens, principally Australian commercial antigen, were skin-tested in Puerto Ricans, other persons of Caribbean origin, and in native-born New Yorkers. The findings suggested that there existed a certain previously unreported degree of cross-reactivity to Casoni antigen in persons with schistosomiasis and possibly in nematode parasitic infections. Geographic matching of controls with cases would, therefore, be necessary in order to determine the usefulness of parasitic skin-test antigens, and the results of population surveys with these antigens would have to be interpreted cautiously. Interpretation of Casoni skin tests with commercial antigens must be made in the light of cross-reactions in persons exposed to other helminth infections. A human-derived antigen, and an animal-derived antigen of low nitrogen content, did not appear to possess any considerable advantage over those that are commercially available.

The dye test for toxoplasmosis was performed on blood samples from 50 foxes, 50 cats, 35 sheep, 432 pigs, and 40 rabbits collected in the area of Siena, Italy. All the animals were apparently healthy, except for 19 rabbits obtained from an epizootic focus. Isolation trials were performed from dye-test positive animals. The incidence of toxoplasmosis was remarkable. A higher number of positive isolations was obtained from animals with higher dye-test titers. Better results in isolation trials could be observed by pooling the inocula from animals with low titers. Numerous strains of Toxoplasma were found in pigs' diaphragms, which are used in Siena as an ingredient of raw sausages. In foxes, cats, and pigs the skeletal muscle appeared to be an important site of cysts in chronic infection. In the rabbit a small epizootic focus was observed, including one instance of generalized asymptomatic toxoplasmosis. A natural congenital transmission is very likely to have occurred in another case.

The addition of sodium citrate to certain accessory-factor (AF) serum samples for inclusion in the Sabin-Feldman dye test decreased the proportion of nonstaining Toxoplasma from unacceptable to acceptable levels. This procedure also made easier the location of suitable AF donors, and eliminated the problem of a precipitate, frequently encountered in plasma intended for use as AF. A paper-disc method for collecting and storing blood for antibody determination was proved to be highly accurate for use in the dye test by comparing the titer of eluate from filter-paper discs containing capillary blood with the titer of serum from venous blood collected from a group of blood donors. It was also observed that blood on filter-paper discs usually could be stored for several weeks at room temperature without appreciable loss of antibody titer. Furthermore, it was demonstrated experimentally that accurate antibody determinations could be made from discs containing blood of rats collected several hours after death.

Histoplasma capsulatum was recovered from the pooled homogenate suspension of lungs, liver, and spleen of six of 50 (12%) Mexican free-tailed bats collected from a western Oklahoma cave. All isolates formed characteristic tuberculate macroconidia and small pyriform microconidia. All were converted to typical yeast forms when subcultured under appropriate conditions of growth. Incubation time necessary for culture of the fungus from infected tissue varied from 21 to 43 days, and the number of viable organisms recovered from each pool of organs ranged from one to 24. These recoveries establish the existence of the natural infection of bats in Oklahoma.

During studies on the emission of Sindbis virus from the mouthparts of experimentally infected Aedes aegypti, virus was detected in the anal discharge. This report deals with the quantity and source of virus expelled from the anus and with the possible significance of these findings with respect to the transmission of arboviruses from mosquitoes to vertebrate hosts. Anal fluid was collected from mosquitoes by several methods during and after the mosquitoes fed on either infant mice, chick embryos, or artificial feeding solutions contained beneath a membrane or within a capillary tube. Infected mosquitoes frequently discharged droplets or spray of virus-containing anal fluid during and after feeding. The probable source of the anal virus was the Malpighian tubules. Infant mice were infected by applying virus to broken skin or nasal mucosa. Sealing the anus of infected mosquitoes did not, however, alter the frequency of virus transmission, by bite, to infant mice. Transmission from infected mosquito to vertebrate host by this “posterior” route deserves further investigation with other arboviruses and appropriate insect intermediate hosts.

A strain of Zika virus (P6-740) was isolated from one of 58 pools of 1,277 Aedes aegypti mosquitoes collected in cities and towns of peninsular Malaya. The mosquitoes in the positive pool were collected from shop houses in Bentong, a small town in West Central Malaya. No strains of Zika virus were isolated from 59 pools of 4,492 Aedes albopictus collected in suburban and rural areas and in rubber plantations, nor from any of 179 pools of 27,636 mosquitoes of 23 other Aedes species collected in rural areas, rain forests, mangrove swamps, and fresh-water swamp forests throughout Malaya. P6-740 was readily identified as a strain of Zika virus by the use of antiserum from monkeys in the standard hemagglutination-inhibition test and the plaque-reduction neutralization test in Vero cell cultures. Specific identification of P6-740 as Zika virus was also made in cross-neutralization tests in mice with hyperimmune mouse serum prepared to itself, Zika, Spondweni, and other group B arboviruses. The latter method, however, was less specific than the plaque-reduction neutralization test for comparison of Zika and Spondweni viruses.

Serum from 2,294 wild birds, 128 mammals, 22 reptiles, and 96 amphibians caught from May 1965 to June 1966 in Israel were examined for antibodies against Eastern equine encephalomyelitis. Semliki Forest, Sindbis, Langat, Israel turkey meningoencephalitis, and West Nile (WN) viruses by hemagglutination-inhibition (HI) tests. The incidence of positive serum was 14.4% for wild birds, 5% for mammals, and 9% for reptiles. No antibodies were detected in the amphibian serum; 73% of the positive avian serum had antibodies against group B viruses. The rest of the positive serum was divided among that positive for group A and that positive for both group A and group B viruses. Serologic conversions in sentinel chickens confirmed the activity of WN virus in the Hadera region during the period studied. Use of acetone extraction followed by kaolin treatment of serum minimized the number of falsely positive results obtained in the HI tests. Good correlation was found between results obtained in HI tests and indirect fluorescent-antibody staining of WN antigen among serum samples from 116 Columbidae examined by these two methods.

A serologic survey for antibodies to arboviruses in serum from domestic animals, cattle and sheep, from the south of Portugal was done with the hemagglutination-inhibition (HI) test. The following viruses were used as antigens: Sindbis, chikungunya, West Nile, Central European tick-borne encephalitis (TBE), Israel turkey meningoencephalitis (ITME), Batai, and Ťahyňa. Of the bovine serum, 16% had HI antibodies to West Nile virus, with titers ranging from 1:20 to 1:5,120; and these specimens also reacted with the TBE antigen (5.1%) and with the ITME antigen (8.2%), but this reactivity was probably due to serologic overlap. None of the serum specimens after acetone treatment gave positive tests with the Sindbis or with the chikungunya antigens. The percentage of serum positive to the Batai and to the Ťahyňa antigens was 2% and 3% respectively.

Eighteen strains of reovirus type 3 were isolated from mice and tissue cultures inoculated with suspensions of mosquitoes caught in the southeastern part of the main island of the Fiji group between 17 April and 12 June 1967. Three strains were isolated originally from rhesus-monkey kidney cells and suckling mice and reisolated from human-embryo kidney cells and suckling mice. Seven further strains were reisolated from suckling mice. Strains of virus isolated from mosquitoes were inoculated into laboratory colonies of Aedes australis and Culex quinquefasciatus and into wild-caught Culiseta tonnoiri. Evidence was obtained of prolonged survival but not of multiplication in these species. C. quinquefasciatus fed on viremic suckling mice were able to transmit to further suckling mice for up to 4 days after the infective feed, but no longer. This is interpreted as mechanical transmission of a highly resistant virus that probably remained active while contaminating the mouthparts of the insects.

Hemagglutination-inhibition, complement-fixation, and neutralization tests in mice were used to detect antibody to 11 arboviruses in 1.389 samples of bovine serum, collected in Queensland, Australia. The neutralizing activity of bovine antibody was low. Evidence is presented that indicates that the serologic response to some arboviruses is short-lived. Group A: Antibody to Ross River virus occurred in 98 serum samples; it was widespread in Queensland but was more prevalent in the southeast. Antibody to Getah virus occurred in 32 serum samples, also widespread but more prevalent in northern areas. Antibody to Sindbis virus occurred in only 13 serum samples, mostly from southeast Queensland. Group B: Thirty-two serum samples had antibody to Murray Valley encephalitis virus, and 29 had antibody to Kunjin virus. Most of these were from North Queensland. One cow had high-titer antibody to Kokobera. There was equivocal evidence for antibody to Stratford, Edge Hill, and MRM 3929 viruses. Koongol group: There was evidence of a low incidence of infection.

Twelve arbovirus isolations were made from about 50,000 bloodsucking Diptera, including Culicidae (mosquitoes). Tabanidae (horseflies and deerflies), Simuliidae (black flies), and Ceratopogonidae (punkies) that were collected during 1965 in Wisconsin. The Jamestown Canyon serotype of the California virus complex was isolated from two species of Tabanidae, the horsefly, Hybomitra lasiophthalma (Macq.), and the deerfly Chrysops cincticornis (Walk.), and from the Aedes stimulans (Walk,) and the Aedes communis (DeG,) groups of mosquitoes. The virus apparently circulated among insects for only a short period (June) during 1965. Other isolations in 1965 included trivittatus virus from Aedes trivittatus and as yet unidentified arboviruses from a black fly. Simulium meridionale Riley, and a mixed pool containing mostly Culicoides.

This study was undertaken to define the nature and extent of arbovirus activity in the environment of Tucson, Arizona; especial interest was centered in the prevalence of arthropod-borne encephalitis. Field collections of mosquitoes, ticks, birds, and small mammals were made in the selected study areas along the valleys of the Santa Cruz River and the Rillito in or near Tucson. Flocks of sentinel chickens were maintained during the hot seasons in the same areas. The virus of St. Louis encephalitis (SLE) was isolated 12 times from mosquitoes in three separate summer seasons. The virus of Western encephalitis (WE) was recovered in the summer of 1966 in three different lots of mosquitoes. The results of serologic tests on the chickens maintained as sentinels in the study areas confirmed that active transmission of SLE and WE viruses had occurred during the summers that the isolations had been obtained. There was a relative scarcity of Culex tarsalis in the areas studied. The explanation for this is not clear. As a result of this study it appears clear that arthropod-borne encephalitis poses a continuing threat to the population of southern Arizona.

Aedes aegypti and Aedes albopictus mosquitoes collected in and near Saigon, South Vietnam, during May through December 1967 were tested for arboviruses in LLC-MK2 cell cultures and suckling mice. Thirty strains of dengue viruses were recovered from 46,862 A. aegypti collected in or near homes of patients with dengue hemorrhagic fever. All four dengue serotypes were recovered, with dengue-2 predominating. High infection rates were noted among A. aegypti in some areas, and multiple virus recoveries from the same area occurred frequently. No viruses were recovered from 8,006 Aedes albopictus tested.

An outbreak of St. Louis encephalitis (SLE) occurred in St. Louis County in late summer 1966. Thirteen serologically confirmed or presumptive cases were observed. The most intense SLE-virus activity was in University City, a suburban community of St. Louis, Missouri. A serologic survey conducted 3 months after the outbreak indicated a low level of antibody prevalence among the residents of University City. Most persons with SLE antibody were in the older age groups. A serologic survey conducted in a nearby community that had no reported encephalitis cases revealed antibody patterns similar to those observed in University City. Four cases of central-nervous-system infection that were investigated were related to Coxsackie virus A9 and two to herpes simplex.

The failure to detect yellow fever-virus antibody in baboons known to have been previously vaccinated suggested an attempt to explain this finding. Accordingly, a study was initiated to test baboon and human serum specimens before and after vaccination for the presence of yellow fever neutralizing antibody, two different preparations of vaccine for determination of antibody being employed. Neutralization tests in mice were employed with 1:5 serum dilutions. The results indicated that good immunologic responses are obtained if the vaccine is handled and used according to specifications. Failures in vaccination arise in the field presumably as a result of mishandling of this highly labile material.

This paper is the result of an analysis of a publication by Muñoz, Pérez, and Scrimshaw in this Journal and of another by the same authors. The former lists the findings in 22 entire departments in Guatemala; the latter, the observations in each of the 105 localities in which the survey was conducted. It notes several inconsistencies and errors in the first paper and concludes that the statement (p. 966): “The incidence of endemic goiter in Guatemala does show a definite correlation with altitude” is contradicted by the facts.

The third paragraph opens with: “A total of 39,484 persons of all 22 departments of the country were examined of whom 70 per cent were school children, 2 per cent pre-school children and 28 per cent adults.”

The total examined, as arranged by sex and age on page 965 is not 39,484 but 39,777 (Table 1) or 39,767 (Table 2), of whom 65.4% were from 0 to 12 years old, 23.3% from 13 to 18, and 11.3% of 19 years or more.

Employing a bacteriologic medium in which the sole nitrogen source was the organic molluscicide. Bayluscide,® isolations were made of organisms from more than 40 field and laboratory sites in Puerto Rico, the Dominican Republic, St. Lucia, and Venezuela. Materials were subcultured four times, then selected strains isolated from the snail Biomphalaria glabrata were subjected to standard diagnostic procedures. In all, six different bacterial strains were identified as members of the genus Pseudomonas and two as members of the genus Aerobacter. Distribution of molluscicide-utilizing bacteria was practically universal, being found in water, sediment, and snail intestinal contents. Bacteria were associated with 15 species of mollusk tested for the presence of such organisms. The possible significance of molluscicide-degrading organisms, relative to snail control projects, is discussed.

World Review of Nutrition and Dietetics, Vol. 9, edited by Geoffrey H. Bourne. x + 290 pages, illustrated. S. Karger, Basel (Switzerland), New York. Distributed in U. S. A. by Albert J. Phiebig, P.O. Box 352, White Plains, New York 10602. 1968. $18.00.

Malnutrition, Learning, and Behavior, edited by Nevin S. Scrimshaw and John E. Gordon, Proceedings of an International Conference cosponsored by The Nutrition Foundation, Inc., and The Massachusetts Institute of Technology held at Cambridge, Massachusetts, 1 to 3 March 1967. xiii + 566 pages, illustrated. The M.I.T. Press, Massachusetts Institute of Technology, 50 Ames Street, Cambridge, Massachusetts 02142. 1968. $12.50.

Der bakteriologisch-serologische Kurs, by Professor Dr. med. habil. Siegfried Ortel, Direktor des Instituts fur Medizinische Mikrobiologie und Epidemiologie der Martin-Luther Universitat Halle, Wittenberg. 185 pages, illustrated. Veb Gustav Fischer Verlag, Villengang 2, Postschliessfach 176, East Germany. 1968. 18.00 M.

This is a small book dealing with the subject of hematology. It is succinctly written in an appealing style. Dispersed throughout the book are timely critical comments pointing out those areas of hematology where there is more speculation than fact. Unlike many other short books on broad subjects, the writer has managed to cover many subjects comprehensively. This is especially true of the chapter on iron deficiency and megaloblastic anemias. The chapter dealing with hematologic findings in diseases of the kidney, liver, and the endocrine system is also good. The section on hemostasis is brief but better than one usually encounters in this type of book. In the tables, figures, and texts of these chapters, one can often find the answers to questions that are sometimes difficult to find in larger, more comprehensive, hematology textbooks.

Most disappointing are the sections dealing with the hemolytic anemias and hematologic malignancies, where much of the discussion is too sketchy to be of much benefit.

This book is a translation by F. K. Plous of the Proceedings of the 4th Conference on Natural Nidality of Diseases in Kazakhstan and the Republics of Middle Asia, held in the Institute of Zoology at Alma-Ata, Kazakhstan, U.S.S.R. on 15–20 September 1959. It begins, appropriately, with a concise review of the scope of the subject by Academician E. N. Pavlovsky, who began a long series of important contributions to the ecology of the zoonoses in 1939 and was the first to use the word “nidality” in this context. Among other ideas, Pavlovsky discusses the possibility that viruses are altered by natural transmission sequences through various hosts. He also pays tribute to workers in other parts of the world and is especially complimentary to Czech and Chinese workers for their methodical contributions. The second contribution is also a review by I. G. Galuzo.

This volume of the British Medical Bulletin contains a brief introduction by J. A. B. Gray, 15 articles on various aspects of computing in medicine, and a glossary of terms. There has been no attempt to cover all aspects of the problem, but rather to give authoritative accounts in a few carefully chosen areas. In particular, the committee that planned this Bulletin decided to leave out from consideration the administrative aspects of the medical services.

The first paper, by L. C. Payne, considers the basic principles of computer technology. The computer can receive, store, select, evaluate, and transmit information—features that are characteristic of the cerebral cortex. Whereas historically machines have been principally concerned with deploying muscle power more effectively, the computer augments cerebral functions. With its help an untrained person can do things that otherwise entail trained cerebral activity. This theme is again taken up in a later article by I. D. P. Wootten, where examples are given from the biochemistry laboratory.

Here is a book on statistical method intended for the medical student and physician. The author acknowledges in the preface that the illustrations used will cause medical experts to shudder, and that, to make the concepts easily understood, he has taken liberties “which would make theoretical statisticians cringe, advanced applied statisticians cower, and pure mathematicians … pretend the book does not exist.” The sad thing about this book is not so much that these liberties have been taken, but that the result will so often still leave the reader perplexed and bewildered.

The first chapter introduces the subject by discussing general topics, using terms that are not defined until much later in the book—“as a result some points made in this chapter may not be fully understood.” This is hardly the way to introduce statistics to the beginner. The author repeats the same mistake, probably unwittingly, later on in the book—terms such as probability sample and normal curve are used long before they are explained.

This book is a softback of some 200-plus pages divided into three sections. In Section I, the author discusses the Urban Environment of a Developing Country from the erroneous attitude of some doctors on the subject of parasitic diseases found through a general description of the country, its people, and all the various factors that make it difficult to have an ideal community free of disease.

Section II describes the pattern of parasitic diseases to include topography, climate, incidence of parasites, and those parasitic diseases of universal prevalence such as amebiasis, malaria, hookworm, onchocerciasis, schistosomiasis, filariasis, etc., and those of sporadic parasitic diseases of limited distribution. He then goes into skin diseases and broadens the parasitic to microbial diseases that certainly are of considerable significance. Parasitic diseases in the rural communities and the effects on children are described. An interesting chapter is “The Fate of Acquired Resistance to Certain Parasitic Diseases in Nigerians Migrating to Urban Areas.”

This is a monograph presented by the author as a thesis for the degree of Doctor of Medicine given to him by the University of Natal in 1965. The book consists of 207 pages including an extensive table of contents covering the preface, eight chapters, a résumé, a bibliography, and 121 figures. Each chapter has many tables.

The purpose of this study was to correlate the disease processes produced by Schistosoma haematobium and Schistosoma mansoni and to assess the lesions produced in relation to morbidity and mortality. This study compares the manifestation of the disease in a local population compared with the findings in other major endemic areas. The Europeans and Indians, most of whom are second- and third-generation in Africa, provided a setting for a comparative study of the effect of schistosomiasis in different races; however, it was not possible to investigate the Europeans in this particular study.

To the Editor:

The paper “Health Protection in a Shrinking World” by David J. Sencer, appearing in this issue of the Journal, contains a potentially dangerous assumption.

The statement is made, with reference to yellow fever, “… surveillance should be such that the initial case, or at least the first generation of cases, arising from an importation is recognized and the second prevented.” It is further stated, “The technology to accomplish this in the case of yellow fever is available with rapid, mass vaccination and vector control.” Unfortunately, although not specifically stated, this leaves the reader with the inference that the technology for early recognition of cases is also available.

It is my belief that the early recognition of yellow fever, “the initial case, or at least the first generation of cases,” cannot be assumed. Yellow fever is manifested clinically not necessarily or even usually by the classic symptoms and signs described in textbooks.

To the Editor:

I am indebted to Dr. David Sencer for a prepublication copy of his Charles Franklin Craig Lecture entitled “Health Protection in a Shrinking World.” Dr. Sencer's recommendations regarding yellow fever are of such grave import that I hasten to comment on them, hoping for simultaneous publication. As one who made his first yellow fever field trip in Brazil in 1920 while General William C. Gorgas was still director of The Rockefeller Foundation's campaign for the eradication of yellow fever, and as one who participated for many years in the study and prevention of yellow fever, I cannot remain silent in the face of these surprising proposals. Especially is it important to state that the words of the Director of the National Communicable Disease Center of the Public Health Service do not necessarily constitute a declaration of official policy of the United States Government.