The American Journal of Tropical Medicine and Hygiene - Volume s1-30, Issue 1, January 1950

• 1.  Seven strains of Trypanosoma cruzi, differing in host-background, geographic distribution, virulence, and history of laboratory propagation were found to be immunologically interrelated. After spontaneous or drug-induced recovery from infection with any one of these strains, mice were immune to repeated challenges with the lethal WBH-strain which killed all non-immunized controls within 13 days.
• 2.  Mouse antisera to the seven T. cruzi strains agglutinated homologous and herologous cultures of the same species at dilutions up to 1:2400, but did not react with Leishmania donovani. Some of the antisera also contained lysins of low titer. Normal mouse sera had no agglutinating or lytic properties.
• 3.  Passive immunization with mouse antisera of high agglutinating titer, or prolonged pre-treatment with formalinized crithidia, blood trypanosomes and lyophilized leishmania stages from infected spleen, did not protect mice significantly against WBH-strain.
• 4.  The sera of four human Chagas' disease patients at dilutions up to 1:200 agglutinated living (but not killed) cultures of six T. cruzi strains. These cultures differed considerably in their response to the natural agglutinins in normal human sera. The “smooth” Culbertson-strain was least reactive with normal sera, hence most valuable as a diagnostic test-antigen.
• 5.  A simple, rapid slide-agglutination routine for the diagnosis of Chagas' disease by means of Culbertson-strain T. cruzi is described.
• 6.  Inter-strain immunity, the nature of the protective mechanism and the present status of clinical diagnosis of Chagas' disease are discussed.

• 1.  Experimental Trypanosoma brucei infection in Peromyscus leucopus noveboracensis (American forest deer mouse) runs a chronic course. Several P. l. nove-boracensis, in spite of being reinoculated two to five times with massive doses of virulent Tr. brucei, lived as long as 617 days. In a few cases, a feeble infection was detectable during this period.
• 2.  Massive reinoculations, even at frequent intervals, failed, with a few exceptions, to provoke a definite relapse of the trypanosomes. The number of parasites in the circulating blood was small, and it was necessary to resort to inoculations of susceptible animals in order to prove their presence.
• 3.  The forest deer mouse exhibits a marked degree of resistance to Tr. brucei. This host is an unfavorable environment for the parasite and Tr. brucei is gradually but markedly attenuated, which was manifested by the prolonged incubation periods in the test animals.
• 4.  When Tr. brucei is kept in unfavorable media (in vitro or in vivo), susceptible animal inoculation tests require careful observations over a longer period than is usually considered sufficient.
• 5.  After the last reinoculation of the forest deer mice, the Tr. brucei were gradually attenuated, and the incubation period in susceptible animals was again prolonged. At times the blood of P. l. noveboracensis failed altogether to produce infection in susceptible test animals (Rattus norvegicus and Mus musculus). The noveboracensis regained a high degree of relative immunity; their blood had acquired a pronounced degree of multiplication-inhibiting and trypanolytic properties.
• 6.  P. l. noveboracensis, because of its inexpensiveness and because of the small amount of space needed when experiments are conducted on a large scale, is admirably suited for cross-immunity tests and for studying the ultimate fate of pathogenic trypanosomes in a reservoir host.

• 1.  The method designed to test whether or not an apparently amebacidal action is exerted indirectly through inhibition of growth of associated bacteria has been applied to nine antibiotics. It was found that all exhibited some degree of indirect action in vitro.
• 2.  The method has also been used to retest seven accepted amebacides. The slight bacteriostasis observed in two of them (carbarsone oxide and vioform) was insufficient to influence the test. No bacteriostasis was otherwise observed.
• 3.  Indirect action through bacteriostasis has been correlated with oxidation of the culture medium.
• 4.  Direct amebacidal action cannot be determined in the presence of an agent having bacteriostatic activity by the method presented.

A staining solution is described which can be utilized in the preparation of wet mounts for the rapid, critical differentiation of trophozoites of intestinal amoebae. It consists of a buffered, aqueous solution of the precipitate obtained upon the interaction of haematoxylin and crystal violet. The staining reaction of other parasites and structures encountered in feces is also presented. The differentiation of trophic amoebae is usually comparable to the good results obtained with any of the permament haematoxylin methods.

Endamoeba histolytica cysts, NRS strain, were exposed to temperatures of 45° to 54.5°C. in a thermostatically-controlled water bath for varying time intervals. The cysts were suspended in a concentration of 2,000 per ml. in 15 to 35 ml. of distilled water at a pH varying from 6.5 to 7.0. The criterion for cyst destruction was the subsequent inability of heated cysts to establish growth in culture. Some estimate of the amount of cyst destruction by heating was obtained by a comparison with growth results of known numbers of unheated control cysts. Failure to obtain cultures in any of 5 tubes inoculated with 1,000 treated cysts each was taken as indicative of 100 per cent destruction.

In experiments at 45°C., the time required for complete cyst destruction was variable, but in all instances was more than 2 hours. At temperatures of 46°C. to 47°C., all cysts were destroyed within 1 hour. At a temperature of 48°C., cyst destruction was complete by 30 minutes. At 49° to 50°C., complete cyst destruction was effected within 10 minutes. At 51°C., all cysts were destroyed within 5 minutes. At temperatures of 52°C. and 54.5°C., all cysts were destroyed within 1 minute.

It was noted that, at the lower temperatures, the time required for complete destruction was considerably in excess of the time required for approximately 99 per cent destruction. At the higher temperatures, this lag was proportionately less marked.

• 1.  An in vitro method of testing the amebicidal action of a chemical agent is described in detail. The results of this study show that flask cultures employing the Balamuth medium are very satisfactory for the uniform growth of trophozoites of E. histolytica in large numbers.
• 2.  Comparative tests on four chemical agents were made. N-Methyl-Emetine-diiodomethylate, a new compound, possesses extremely low amebicidal action in vitro. These agents arranged in the order of their amebicidal action are emetine hydrochloride (1 part in 80,000), Iodochloroquine (1 part in 6,000), Chloroquine (1 part in 4,250) and N-Methyl-Emetine-diiodomethylate (1 part in 50).
• 3.  Only an approximate estimation of the effectiveness of drugs as amebicides can be determined from in vitro studies.
• 4.  N-Methyl-Emetine-diiodomethylate has very little amebicidal activity in vitro.

• 1.  Camoquin, a 4-aminoquinoline compound, was administered in a single dose of 10 mgm/kg. to 30 patients with vivax malaria and to 20 with falciparum malaria.
• 2.  Among both the vivax and the falciparum patients, all temperatures were normal within 48 hours of treatment; the average temperature was normal by 32 hours after treatment.
• 3.  Parasitemia disappeared quickly, the time averaging 37 hours for vivax cases, 30 hours for falciparum cases.
• 4.  Only one vivax clinical relapse occurred, although patients were under observation for periods of 6 to 16 months.
• 5.  Camoquin is a relatively non-toxic drug.
• 6.  Camoquin deserves more widespread use in malarious areas throughout the world, and should be particularly valuable in rural locations and/or when hospitalization of the patient is not feasible.

The finding of several infections of Balantidium coli in man (Young, 1939) afforded the opportunity of attempting some transmission experiments. Such experiments appeared justified because of the lack of information on the transmission of this parasite.

The sources of the balantidia were several very active human infections. Fecal material containing trophozoites and cysts was put into gelatin capsules and swallowed by the volunteers. The trophozoites were motile. The cysts were viable as indicated by movements of the encysted parasites.

The pertinent data are shown in Table 1.

Volunteer My received a small number of cysts and did not develop an infection during a 40-day observation period. Transmission was again attempted in this volunteer as well as in a new volunteer, Jk. On this trial approximately 250 cysts and 250 trophozoites were given each volunteer. During the following observation period of more than 10 years, no B. coli parasites appeared in the stools of either person.

In Texas, one hundred cases of relapsing fever were confirmed by demonstration of spirochetes in thick films of the patient's blood, or in blood films of rodents inoculated with a small amount of the patient's blood, during the period June, 1942 through May, 1949. The cases occurred chiefly in the central part of the State, with scattered cases in all but extreme East Texas. During the same period of time, specimens of Ornithodoros turicata, have been taken in 44 Counties, representing all sections of the State but East Texas. In all but 8 of the Counties, pools of the ticks were shown to contain individuals harboring spirochetes.

A method for the isolation and identification of Shigella and Salmonella from fecal specimens has been described. For convenience in performance the procedure was set up under five main divisions; planting, screening, presumptive serology, biochemical confirmation and serological identification. The simple screening and presumptive serological tests adopted have been found to reduce to a minimum the number of organisms that require further biochemical and serological study for complete identification.

There appears to be no doubt that gentian violet is at the moment the drug of choice for the treatment of human strongyloidiasis. The oral regimen (0.06 gm. gentian violet medicinal in 1½ hour enteric coated tablets t.i.d. until 3.3 gm. have been administered (1)) is apparently widely used, supplemented at times by the transduodenal intubation of a solution of the drug. There are, however, at least two disadvantages to enteral therapy in this disease: the length of the therapeutic course necessary before the stools become larva-free—sometimes amounting to several months—and the failure of the drug to be absorbed from the gastrointestinal tract; the enterally administered dye does not reach the stages of the organism which do the greatest harm—the migrating larvae of the initial infection and of the auto- and hyperinfection stages.

During the management of several cases of strongyloidiasis, it became necessary to treat patients in whom there was dangerous active larval migration, as evidenced by pulmonary inflltratioias and renal hemorrhage, with larvae demonstrable in the sputum and urine.

Surveys conducted in mental institutions and on general population groups show high incidence of infection with Enterobius vermicularis. A survey was made in this hospital to determine the rate of infection among the patients caused by this nematode.

Examinations where made by sections on each Ward, to establish the incidence of infection of each group, with the exception of Ward I where all the patients were considered one group. In all, 1,460 patients were examined by NIH swabs (Hall's anal swab), of whom 176 were found to be infected with E. vermicularis. For a check, 349 patients with negative results were reexamined, but no additional case could be detected. Specimens were taken mornings at 8 o'clock.

The infection rate of 11.98 per cent in 1,460 patients examined is low as compared with results obtained by Cram of the National Institute of Health, who reported on incidence of 35 per cent in 600 persons of various general population groups in Washington, D. C., and Smith who found the unusually high infection rate of 65.15 per cent in an institution for mentally deficient.

Field studies of tick repellents were conducted at Bull's Island, S. C., and Camp Bullis, Tex., in the spring of 1948. Thirty-nine repellents, selected from previous experiments, were tested in South Carolina, and 19 of these were tested in Texas. Acetone solutions of each compound, and emulsions and dusts of some, were used to impregnate army cotton fatigue uniforms. The liquids were applied at the rate of about 2 grams per square foot of cloth, and the dusts at 0.1 gram. The uniforms were worn in areas heavily infested with the lone star tick, Amblyomma americanum (L.). Some uniforms were tested daily and others intermittently (weekly for 3 to 5 weeks) after treatment. The ticks in South Carolina were much more active than those in Texas, but the results in the two localities were in general agreement. In South Carolina the ticks were unusually aggressive when the daily tests were under way, and some of the compounds that were highly effective in all other tests gave relatively poor results in this series.

The materials were divided into four groups based on the information available as to their toxicological effects on warm-blooded animals. Of the most effective repellents, those that appeared to be safe for use either on clothing or by direct application to the skin were Indalone, hexyl mandelate, dimethyl carbate, ethyl beta-phenylhydracrylate, 2-butyl-2-ethyl-1,3-propanediol, 2-phenoxyethyl isobutyrate, and diethyl phthalate. Those deemed safe for use on the clothing but not as liquids applied to the skin were N-butylacetanilide, 2-[2-(2-ethylhexyloxy)ethoxy]ethanol, Thanite, hendecenoic acid, isobornyl 4-morpholine-acetate, and 2-phenylcyclohexanol.

The other effective materials were either of undetermined toxicity or appeared to be unsafe for extended use on clothing.

Solutions and emulsions appeared to be about equal in effectiveness. Two compounds gave considerable temporary protection when applied as dusts, even though the dosage was very light.

Of the three important mosquito-borne diseases occurring throughout the Pacific Ocean areas, dengue was of paramount importance on New Caledonia. The disease has been known since 1885 and the virus appears to have been introduced by surface vessels from endemic areas as Indo-China. Epidemics have been reported in the literature for several years following the initial outbreak in 1885.

The chief vector on the island is A. aegypti. With the institution of control measures in 1942 directed against the domesticated habits of this transmitting agent, the incidence of dengue dropped dramatically over a three-year period. By 1946, only an occasional case was reported in the civilian and military population of Noumea.

Malaria has been reported only as secondary cases in American combat troops undergoing “demalarialization” on New Caledonia and in the indentured Javanese and Tonkinese laborers employed in the nickel mines of the island. Primary infections in these patients were acquired in other endemic malarious areas.

Species of the genus Anopheles have not been discovered and the consensus of opinion among entomologists is that New Caledonia remained anopheline free up to the cessation of active military occupation in 1946.

W. bancrofti has been reported by blood film studies; C. quinquefasciatus is believed to be the most important vector.

Larval surveys revealed thirteen species of mosquitoes represented by the genera Aëdes, Culex, Mansonia, and Tripteroides.

September 27, 1949

Dr. Mark F. Boyd, Editor,

The American Journal of Tropical Medicine

615 East Sixth Avenue

Tallahassee, Florida.

This is in reference to the paper by Berberian and Dennis in the July 1949 issue of the Journal, entitled “Chloroquine Diphosphate and Malaria Splenomegaly.”

The confusion of terms in referring to spleen measurements in malaria is unfortunate. Hackett (Jour. Nat. Mal. Soc. 3: 121–133, 1944) proposes a standardization of terms when referring to averages of spleen sizes:

AES (Average Enlarged Spleen) equals the sum of the products of the weighted groups divided by the number with enlarged spleens. AES can never be less than 1.0 nor can it exceed 5.0.

AS (Average Spleen) equals sum of products of the weighted groups divided by the total number of children examined. AS can vary from 0.0 to 5.0.

Russell, Manwell and West (Practical Malariology p. 391–392) do not recognize the AS as defined above and their AES is equivalent to the AS of Hackett.

Note: Books received for editorial consideration will be intermittently listed. This acknowledgment must be regarded as an adequate expression of appreciation for the courtesy of the author or publisher. Selections will be made for review in the interest of our readers.

M. D. Altschule. Physiology in Diseases of the Heart and Lungs. Pp. xvi plus 368. Clo. Cambridge, Harvard University Press. 1949. $5.00.

Asa C. Chandler. Introduction t. Parasitology with Special Reference to the Parasites of Man. Pp. xii plus 756. Figs. 273. Clo. 8th ed. revised. New York, John Wiley and Sons, Inc. 1949. $6.00.

Edmond Sergent, Directeur. Rapport sur le Fonctionnement de l'Institut Pasteur d'Algérie en 1948. Pp. 41. Wrap.

Memoria de la Campaña Nacional Contra El Paludismo. Pp. 189. Figs. 76, Maps 27. Wrap. Mexico, D. F. Secretaria de Salubridad y Asistencia de los Estados Unidos Mexicanos. 1949.

Leon J. Warshaw. Malaria, the Biography of a Killer. Pp. x plus 348. Clo. New York and Toronto, Rinehart and Company. 1949. $3.75.

There are so few texts and reference books on fungous diseases of man that a new handbook on the subject, designed primarily for physicians and medical students, elicits unusual interest. The main difficulty in the field of medical mycology is that students of the fungi are almost without exception untrained in clinical medicine and that practitioners of medicine have little or imperfect knowledge concerning the etiology of mycotic infections. While the volume under review has been written from the clinical point of view, it evidences considerable understanding of the agents responsible for the pathological and clinical pictures referred to as the “Mycoses.” The book is divided into twelve chapters, which will be briefly considered.

Chapters I and II deal with the general features of mycology, including the etiology of mycoses, together with definition, structure, reproduction and classification of the fungi. This material is well presented and complete with the exception of the classification, which is confinedto the Eumycetes, whereasthe Pseudomycetes,which include Actinomyces and NOCardia, are omitted.

The publication of the third edition of Faust's “Human Helminothology” attests the recognition of the importance of parasitology in today's medical curricula, and the popularity of this standard text on the subject. This new volume is somewhat smaller and has fewer pages than the second edition, but the page size is larger.

The text matter is arranged on the pattern of the former editions. The main interests are historical, biological, clinical and epidemiological. Two new sections have been added: (a) Section V, the nematomorpha, which previously was included under the nemathel minthes or roundworms, and (b) Section VI, the annelida, which is new. All chapters have been revised and improved. The chapter on anthelmintics is thorough and complete. The introduction of a glossary of zoological and medical terms is a notable addition. The definitions, however, are not always clear or correct, particularly those pertaining to some larval stages of tapeworms, such as cercomer, coracidium, hydatid cyst and proceroid.

This entertaining popular book on malaria is written by a physician unknown to contemporaneous malariologists, who is professionally, we understand, a cardiologist. The writer consequently cannot be expected to have had a great deal of personal familiarity with the many problems which this group of diseases affords, and the work is consequently a synthesis of the literature. To this circumstance, and unacquaintance with current trends, may be attributed such an exaggerated statement that there is now, in the United States, an annual average of 4,000,000 cases per year. While such a declaration would have had a certain validity a decade or more ago, its current reiteration sounds strange at this time when health authorities are using a fine toothed comb to discover bona fide cases of indigenous malaria, while because of this steady and rapid decline, the members of the National Malaria Society are seriously discussing the propriety of enlarging the scope of their interests to compensate for the diminished importance of malaria.

This book represents the first attempt to systematize the extensive data relating to insect pathology, a subject of great practical importance to entomologists, both general and specialized.

Its scope is indicated by the titles of its fourteen chapters. The introductory chapter is followed by one discussing mechanical, physical and chemical injuries, including the action of insecticides. This is followed by one treating of nutrition and metabolism. The extracellular microbiota of healthy insects and the intracellular microbiota, each receive one chapter. Likewise infection and epizootiology, as well as resistance and immunity, are discussed in companion chapters. A further chapter is devoted to symptoms and pathologies. Separate chapters deal with bacterial infections, fungous infections, virus infections, protozoan infections and nematode infections. The concluding chapter discusses applied insect pathology and biological control. To each chapter is appended an extensive bibliography.

Although the literature relating to the pathology of insects is extensive, it is widely scattered, and there has been no single source or treatise to which an entomologist in rapid search of information could conveniently turn.