The American Journal of Tropical Medicine and Hygiene - Volume 11, Issue 3, 1962

I want first of all to express my thanks to the members of the Society for the honor and privilege of serving as your president during the past year. There are many reasons why we should be proud of our membership in this Society, the most important being that we are associated with, and participating in, a truly global effort in the field of Medicine, Medical Research and Training. The Society has contributed much, during its fifty-eight years of continuous activity, to the leadership and support of health and medical care programs which have involved disciplines in all areas of basic and applied science, and has incorporated peoples of all areas of the globe. We are, in all our efforts, an international organization.

A brief review of the early history of the American Society of Tropical Medicine seems proper in view of present developments in world affairs.It is of interest to note that a small group of physicians met on March 9, 1903 for the formation of an organization in Philadelphia for the Study of Tropical Diseases.

Twenty patients with intestinal amebiasis were treated with Entamide furoate. Nine were suffering from acute amebic dysentery, ten from chronic amebic colitis, and one was an asymptomatic cyst passer. In all the cases except two, stools became negative on the 3rd or 4th day, in one case on the 11th day, and in another on the 14th day of therapy. In five cases followed up for one month, stools remained negative. It is concluded that Entamide furoate is an effective amebicide, useful in both acute amebic dysentery and chronic amebic colitis.

Three groups of guinea pigs were inoculated with cultures of Entamoeba histolytica or with its associated bacteria: (a) normal, (b) with elevated intestinal cholesterol content, and (c) with hypercholesterolemia. Part of the normal group was inoculated in the cecum and the others in the superior mesenteric vein. The guinea pigs with elevated intestinal cholesterol were inoculated in the cecum while those with hypercholesterolemia were inoculated in the superior mesenteric vein.

The animals which had elevated cholesterol and were inoculated with E. histolytica in the cecum developed larger lesions with greater frequency than did the normal animals.

In the liver, amebic abscesses were found almost exclusively in guinea pigs with hypercholesterolemia, and in these animals the abscesses occasionally were large (1 to 2 cm in diameter) and frequently were numerous.

A strain of Entamaeba histolytica-like ameba (Laredo) cultured at both 37° and 25°C, E. moshkovskii also growing at both temperatures, and E. histolytica K9 were exposed to five anti-histolytica sera conjugated with fluorescein, as well as to a normal serum control.

Laredo at 37°C stained similarly to E. histolytica K9 with four of the antisera, whereas E. moshkovskii at the same temperature stained to a distinctly lesser degree. With the fifth antiserum, Laredo at 37°C stained much less than E. histolytica K9, whereas E. moshkovskii did not stain significantly at all. Laredo at 25°C stained distinctly less than E. histolytica K9 and was similar to E. moshkovskii at both temperatures in this respect.

It is concluded that the Laredo strain resembles E. histolytica antigenically more than E. moshkovskii does, but is not completely typical of E. histolytica in its staining reactions with fluorescent antisera.

Detailed histopathological examinations of tissues of resistant and susceptible hosts to Schistosoma mansoni were made to study the mechanism of resistance to schistosomiasis in abnormal hosts. The reaction to initial infections in 13 species of mammalian hosts confirmed the wide spectrum of host parasite relationships outlined by parasitological methods. The Hoeppli phenomenon was observed in the woodchuck. In the opossum eggs for the most part failed to gain access to the intestinal mucosa and the organ loads were very high. In the cottontail rabbit, the liver was the sole target organ and it absorbed nearly the entire egg production of the relatively few adults. In the muskrat, parasite development was stopped before adulthood was reached, but schistosomula reached the lungs where some evoked a granulomatous response and were trapped. In the fox, schistosomula were trapped in the corium and subcutaneous tissue and destroyed in situ. The implications of the striking similarity between the cellular reaction observed in the abnormal hosts and that in immunized laboratory animals was discussed in relation to known humoral and cellular mechanisms of defense.

A case of bilateral infarction of the testis due to schistosomiasis of the spermatic cords, the first such case to be reported, is described and two possible theories of the genesis of the lesion are discussed.

The resistance of Echinococcus granulosus eggs to several germicides was determined by comparing their hatching and activation rates to those of unexposed controls.

Five per cent sodium hypochlorite caused prompt dissolution of the egg shells, but 31 to 42% of the oncospheres were viable after 90 minutes exposure. In 1 to 2% Tide®, almost all oncospheres hatched; up to 63% of the oncospheres were living after 24 hours, but 6 hours exposure to a 5% solution dissolved all eggs. Roccal® reduced the hatching rate slightly; up to 11% of the oncospheres were living after 30 minutes exposure to concentrations of 1,000 ppm; and an occasional oncosphere survived concentrations of up to 2,000 ppm for 30 minutes. Hatching rates were decreased after long exposure to 70 and 95% ethyl alcohol; 20 to 30% of the hatched oncospheres were viable after 60 minutes. Lysol® solutions reduced hatching rates at higher concentrations, but up to 10% of the hatched oncospheres were living after 60 minutes exposure to a 10% solution; some oncospheres survived a 20% concentration for 30 minutes. The effect of 5 to 20% formalin was to fix the shells and prevent hatching; when shells were artificially removed with 1% sodium hypochlorite the oncospheres were found to survive exposure to 20% formalin for 24 hours.

Recently several cases of human infections with the double-pored tapeworm, Dipylidium caninum, have been reported. It is well known that this tapeworm is a cosmopolitan parasite of dogs and cats and over 100 human infections, mostly in children, have been reported from many areas of the world. To date in this country there have been only eighteen cases of dipylidiasis recorded. The two noted here are from Texas and Florida thus raising the total to twenty.

The first of these two cases (M. T.) was diagnosed in 1954 and was referred to one of us (GWH) for diagnosis by a physician practicing near San Antonio, Texas. The patient was a 7-year-old girl whose only symptoms were periodic, generalized abdominal pain especially when at stool, general irritability, and perianal pruritus. Because of the pruritus pinworm had been suspected and several scotch tape preparations had been submitted for examination.

The incidence of infections with Ascaris lumbricoides and Trichuris trichiura among the Jewish population of Jerusalem during the years 1934 to 1960 based on the results of 126,000 fecal examinations is reported. Until 1948 the infection rate of both parasites was very high, Ascaris infection being found in more than 40% of the population. During the last decade, since the separation of the Israeli part from the Jordanian part of Jerusalem, a sharp decline in the infection rate of both parasites has been noted. A. lumbricoides infections were almost eliminated. It is suggested that the complete stoppage of the supply of contaminated vegetables and fruits from Arab Jordanian villages was responsible for the remarkable drop of A. lumbricoides and T. trichiura infections in Israeli Jerusalem.

Albino rabbits immunized with lyophilized, in vitro hatched, second-stage Ascaris larvae and nonimmune rabbits were challenged intravenously with a suspension of live “in vitro” hatched larvae. Those injected into immune animals were immobilized in septal capillaries of the lung and degenerated rapidly. As a result, few hemorrhages were noted in the lungs. On the other hand, larvae injected into control animals migrated readily to the interstitium and alveolar spaces causing extensive hemorrhages. Most of the larvae were found in the alveolar sacs of control animals as late as 12 days after inoculation; of these, many had developed into advanced-stage larvae. No larvae were found in immune animals after 4 days.

Although the inflammatory response appeared quickly in both immune and nonimmune rabbits, it was more intense in the former. The acute inflammatory reaction was characterized by accumulations of neutrophils and eosinophils. This was later replaced by a granulomatous process containing abundant epithelioid cells, multinucleated giant cells and, in the immune, by the presence about degenerating larvae of an intensely acidophilic material intimately related to the cuticle of the larvae. This material, which is probably an antigen-antibody complex, was never observed in control animals. The granulomatous process lagged by 24 to 48 hours in the controls as compared with the immune animals. Resorption of the granulomas was almost complete 20 days after challenge in the immunes and had markedly decreased in the controls 30 days postinoculation. It is suggested that the X-ray findings described in the so-called “eosinophilic pneumonia of ascariasis” may be the result of a granulomatous process rather than being due entirely to accumulations of eosinophilic granulocytes.

The rapidity with which the acute and the granulomatous inflammatory responses appear both in the immune and control animals indicate that mechanisms other than hypersensitivity may play a role in the defense against Ascaris larvae. There was no relationship between the levels of circulating antibody and the severity of the lesions found. No decrease in circulating antibody was observed after the challenging dose was administered.

A study is presented in which the problem of acute gastroenteritis in infants is investigated by performance of bacteriologic, parasitologic and virologic analysis of 29 fecal samples collected from Puerto Rican infants with diarrheal disease. The study revealed 10 enteropathogenic Escherichia coli, one Shigella, one Salmonella, 4 pathogenic protozoa, and 15 viral agents. Ten strains of E. coli 01 through 024 were recovered from the same samples and included in the study as representative of non-enteropathogenic serotypes. The serologic response against these isolates was determined in every instance where this was possible. Bacterial substance antigenically related to the E. coli serotype present in the intestine was detected in the sera of several patients. Rises in hemagglutinin titer occurred to both pathogenic and “nonpathogenic” E. coli. A neutralizing antibody response was detected for 7 of the 15 virus isolates; 5 of the viral agents isolated are apparently new enteroviruses. Multiple infections were found in 39% of the cases on whom complete studies were undertaken. The study here presented indicates that the multiplicity of infectious agents in the intestinal flora of infants with diarrhea must be considered in any etiologic investigation of this problem.

Field studies in seven villages in representative parts of Guatemala produced evidence of a high community dosage of Shigella and a relative infrequency of Salmonella. Rectal swabs, taken every 2 months from approximately 1,000 children over a period of 2 years and cultured bacteriologically, gave an average infection rate of 6.0% for Shigella, with a range from 0 to 17.2%. The rate for Salmonella was 0.2%.

By periodic prevalence determinations, a seasonal increase in Shigella infection was identified during March through May, although a secondary autumnal increase sometimes occurred. The major frequency of infection was among children aged 2 to 4 years. Infection rates were higher in the lowlands than in the highlands. Less infection occurred among Indians than among non-Indians.

Bacteriological examination of 201 Guatemalan children with acute endemic diarrheal disease showed an association with Shigella in 13% of cases. The carrier rate for that infectious agent in 225 control children of the same ages, 1 through 5 years, was 6%. Examination was by single rectal swabs.

Neither Salmonella nor enteropathogenic E. coli was frequent in the age group examined. Except for hookworms in patients from rural areas, helminths and protozoa were present in equal proportions in persons with and without diarrhea. Guatemalan children showed a high rate of intestinal parasitism, since by 3 years of age practically every village child was infected with at least one species.

The critical question still unanswered is what proportion of acute diarrheas in childhood is of infectious origin. The problem has two parts, the specific infections of the intestinal tract and the many other infectious diseases which on occasion lead to diarrhea. The place of the viruses as inciting agents in both groups needs attention.

Officially reported death rates from acute diarrheal disease for children in the first year of life show Guatemala to occupy a middle position among countries of the Americas. For the age group 1 to 4 years, the rates exceed those of any other. Distribution of deaths by months and years suggest recurring outbreaks of acute diarrhea, closely spaced, of varying size, of relatively long duration, and of an epidemiologic pattern consistent with spread by contact infection. The recorded causes of deaths should be interpreted as actually due to a synergism between infection and malnutrition.

Field studies of a Guatemalan highland child population aged less than 6 years established an annual case incidence of acute diarrheal disease that ranged from 135 per 100 pre-school children during a beginning epidemic to 41 per 100 during a more or less endemic period at the end of an outbreak. Repeated attacks in the same child in the course of a year occurred in both situations, but more frequently as general incidence increased. Attack rates were greatest at ages 6 through 17 months and continued at excessive levels during the second and third years of life. Frequency of attack and severity of illness coincided with the ages at which kwashiorkor is commonest.

The incidence of skin sensitivity to histoplasmin, tuberculin, and blastomycin in a population of 447 Liberians, predominately working males, was found to be 15.4%, 80.8% and 1.6% respectively.

There was no evidence for cross reaction between any of the antigens used.

Of the histoplasmin reactors 70% were followed by chest x-rays. Of 48 chest films examined only 11 showed pulmonary lesions, and only 9 (18.8%) of these consisted of calcifications. All but one of the positive x-rays were of subjects who were also tuberculin positive, and none of the lesions seen was absolutely typical of histoplasmosis.

Bimiti virus is a new agent isolated from Culex mosquitoes collected in the Melajo Forest of Trinidad. Its isolation, identification and behavior in various animals and tissue culture are reported. Limited studies disclose a very low incidence of immunity to this virus in the human population of Trinidad.

From experimental crossings of male Pomatiopsis lapidaria and female Oncomelania quadrasi, but not from the reciprocal crosses, hybrids, which were intermediate between the parent types and produced an F2 generation, were obtained. Crosses between male P. lapidaria and female Oncomelania formosana produced offspring which died before adult characters became evident.

In 21 untreated and 7 treated patients with sprue and 12 normal persons the average daily urinary excretion of folic acid was found to be 2.0 ± 0.9, 3.4 ± 1.5 and 5.6 ± 1.4 micrograms, respectively. The difference between the average amounts excreted by the sprue patients and the control group is statistically significant.

The sixteenth annual conference in the protein metabolism series sponsored by the Bureau of Biological Research, Rutgers University, represented the contributions of eight individuals. The conference was a departure from those preceding it in that no attempt was made to emphasize the relation of the subjects to proteins and protein metabolism. A diversity of papers was presented. Following the introductory remarks by T. von Brand, in which the general development of the field was outlined, L. R. Cleveland spoke of “Effects of insect hormones on the protozoa of Cryptocercus and termites.” J. D. Fulton presented a paper on “Some aspects of research on trypanosomes” followed by a discussion of “Factors influencing the rumen protozoa” by R. E. Hungate. Next, A. R. Timms presented a discussion on “Schistosome enzymes” followed by a paper on “Physiologic aspects of egg hatching and larval exsheathment in nematodes” by D. Fairbairn.

This volume records the papers presented, and the discussions which followed their presentation, at the second Symposium on Perspectives in Virology held in New York City in January, 1960. Following a first Symposium in 1958, it is to be hoped that these are but the beginning of a long series of unusually valuable conferences, and that those which follow are published in like fashion, for there is little doubt that they will “attract and stimulate interest, and serve to orient the general scientist to the exciting new developments of virology” (Dr. Morris Pollard).

The papers in this volume are not original reports of investigation, nor are they systematic chapters arranged in textbook style. Rather, each is a brief review, sometimes highly technical, sometimes discursive, sometimes philosophic, of a limited subject. They range from “fundamental to applied biology, from explorations in new fields and concepts to re-evaluation of established ones”.