The American Journal of Tropical Medicine and Hygiene - Volume 13, Issue 2, March 1964

Through some quirk in the democratic process followed by this Society in the selection of its president I have been chosen to stand before you this evening presumably to spill forth words of wisdom. I am grateful to you for this honor. Our joint meetings with the American Society of Parasitologists are particularly happy and beneficial occasions. Being a charter member of that Society I am pleased to have the opportunity to present my views to you also. This is a particularly auspicious occasion for me by virtue of the fact that it occurs in a city where I spent about one-half of my professional life.

The concern of this Society is with the health of peoples in tropical countries. I shall be talking about parasitic diseases in tropical areas and, hence, my remarks are as appropriate before one Society as the other.Our national interests include more than improvement of the health of people in tropical areas of the world.

A new species of malaria parasite, Plasmodium youngi, is described from the Malayan whitehanded gibbon, Hylobates lar lar. The parasite is tertian in periodicity and produces quite severe infections in the type host with peak parasite densities higher than 100,000 per cmm. The young trophozoites are characterized by the frequent occurrence of double or multiple chromatin. Ameboidicity is great and “tenue” forms are seen frequently. Stippling of the Schüffner type is produced but there is no erythrocyte enlargement at any stage. In the older trophozoites and the younger schizonts there is frequently an accessory chromatin granule at the border of the parasite or extruded into the host erythrocyte. The mature schizont has 12 to 20 (average 14) merozoites which are randomly arranged. Pigment consists of dark, yellowish-brown, discrete granules and is moderate in amount.

Two other species of gibbon were found to be susceptible but the rhesus monkey was not. Anopheles maculatus is somewhat susceptible to infection to the oocyst stage, but sporozoites failed to develop in the mosquitoes studied.

Using the indirect fluorescent antibody method, the production and persistence of specific antibody was demonstrated in patients inoculated with blood parasites of Plasmodium falciparum.

With P. falciparum (Thailand strain), antibody developed in response to the presence of patent parasitemias and the titers fluctuated significantly during the primary attack, apparently in a delayed direct association with fluctuation in parasite densities induced by non-curative dosages of antimalarial drugs. The rapid antibody response and long antibody persistence in the one patient with P. falciparum (Colombia strain) indicated either a possible previous exposure to malaria or a response peculiar to the strain of P. falciparum concerned.

Antibodies to the Colombia strain were shown to persist for up to 20 months after sporozoite inoculation with little or no decrease in antibody titer between 12 and 20 months.

Of 367 North Italian women, either gynecological or obstetrical patients, examined by combined culture methods, 111 were found to be infected by Trichomonas vaginalis, 159 by Trichomonas tenax and 138 by Entamoeba gingivalis. The statistical study of the eight possible combinations of the three infections does not reveal any relationship of association or exclusion among the three parasitoses.

Twenty cases of parasitologically proven kalaasar from the Sudan were studied for evidence of parasitemia by meticulous examination of venous blood smears and intraperitoneal hamster inoculation with venous blood. By the technique used, venous blood smears had demonstrable Leishman-Donovan bodies in 35 percent of the cases. Impression smears and cultures of the spleen from hamsters inoculated with venous blood were positive for parasites in 45 percent of the cases. By all methods, 65 percent of the cases showed parasitemia. No association was found between pyrexia and parasites in the blood. There was no correlation between duration of illness or leukocyte count and leishmania demonstrable in the blood. Circulating parasites were found during the day and early evening, but results were too limited to ascertain whether they were present at night or periodically. By the criteria used, those individuals considered to be more heavily parasitized more frequently had parasitemia. In one case, leishmania did not disappear from the blood despite 4 days of treatment with sodium stibogluconate.

A study of the clinical and pathological course of experimental myotropic Chagas' disease in the mouse is reported. Forty-nine C3H mice, 3 to 5 weeks of age, were inoculated with a Colombian strain of Trypanosoma cruzi. Observations of body weight, spontaneous activity, parasite counts and histopathology were made up to 388 days following inoculation.

The disease was characterized by a benign parasitemic stage, followed by a chronic progressive myocarditis and myositis. During the first 2 months after the inoculation, infected animals could not be differentiated in appearance and body weight from control animals. Parasitemia reached a maximum at the end of the first month and subsided at the end of the second month. Gross pathologic examination during this stage of the infection showed consistent splenomegaly. The mean heart weight of infected animals did not differ significantly from that of the controls. Microscopic study revealed moderate infiltration of cardiac and skeletal muscle and occasional intracellular T. cruzi.

In the third month, the infected animals began to show ruffled fur, spotty alopecia, and progressive weight loss. In time, the infected animals appeared more ill, and deaths occurred. Spontaneous activity, measured from the fifth through the eighth month of infection, was consistently and progressively lower in the infected animals than in the controls. Gross pathologic examination in these later stages of the disease frequently revealed muscle wasting and cardiac enlargement. Between the sixth and the thirteenth month mean heart weight in relation to body weight in infected animals was significantly greater than in control animals. Microscopic study revealed continued and increasing involvement of cardiac muscle. Intracellular organisms were irregularly present in cardiac muscle to day 388.

A total of 1,357 subjects was skin tested with toxoplasmin. Of this number, 26.4% were positive with a definite preponderance of positive reactors in the older age groups.

There was a significant variation between students of medicine and veterinary medicine, between city and rural high school students, between city and farm residents and between persons with maximum and minimum animal contact as defined in this study.

No significant influence was apparent in the evaluation by geographic residence, sex, dietary habits, occupation, or sanitation, with the possible exception of the consumption of raw eggs.

Serum iron concentration and iron absorption tests were made in 20 healthy controls and in 40 patients with hepatic fibrosis associated with Schistosoma mansoni infection who had no anemia. In normal people the fasting serum iron varied from 75 to 174 micrograms per 100 ml, and after administration of ferrous gluconate the serum iron increased only slightly (iron saturation). In patients with bilharzial hepatic fibrosis the fasting serum iron was low in 22 percent and normal in 8 percent, and in both these groups, i.e., 30 percent, the serum iron exceeded the maximum empirical value of about 200 micrograms per 100 ml after oral administration of ferrous gluconate; this indicated the presence of an iron deficiency state (masked sideropenia). In the remaining 70 percent the fasting serum iron and the iron absorption test were normal (iron saturation).

The first confirmed case of ectopic human fascioliasis in Iraq is reported. Based on morphological characteristics, the fluke recovered was identified as an immature specimen of Fasciola gigantica. The source of infection is believed to have resulted either from the consumption of certain raw vegetables or from contaminated water containing the metacercarial stage of the parasite.

A lone female Ascaris, passed spontaneously by a 2-year-old child, was engirdled by, and apparently strangled in, a shoe-eyelet. It is suggested that the occurrence possibly can be attributed to the worm's mating reflexes rather than to a more general tendency to probe small apertures.

Morphology of the peripheral blood and bone marrow was studied, and intestinal absorption tests and jejunum biopsy were performed in 22 patients harboring heavy hookworm infection. Fat absorption, measured both chemically and with oleic acid marked with I131, was normal in all but three patients who showed slight increase of excretion. d-xylose was poorly absorbed in 1 of 18 cases tested. Serum vitamin B12 concentration was significantly diminished although a value below 200 µµg per ml of serum was seen in only one case. Schilling test performed in 8 patients showed 24-hour urinary excretions of B12 Co58 of over 10 percent. On the other hand, there was low folic acid serum concentration and impairment of absorption.

Morphological changes in the peripheral blood and bone marrow suggestive of either vitamin B12 or folic acid deficiency were seen in five cases. In four of these cases which were examined for serum folate activity, values below 4.6 mµg per ml of serum were found.

Jejunum biopsy, performed in 18 cases, showed only slight non-specific changes in 14. Of the other 4, one showed frank atrophy of the mucosa, a second showed flattening of the mucosal surface and fusion of the villi, and the other two showed marked infiltration, especially around the crypts. The results obtained here indicate that hookworm infection per se, without the association of other factors such as malnutrition and other parasitic infections, does not as a rule lead to histological changes in the mucosa which might cause malabsorption of nutrients.

A subcutaneous filarial nodule in the breast of a female due to an adult filarial worm or worms is reported from Mangalore, India. Since Wuchereria bancrofti is endemic in this area, the parasite is regarded as probably being of this species.

Pathologically the worms excited severe endolymphangitis and perilymphangitis. The cells comprising the exudate around the dead and degenerated worms (or portions thereof) were predominantly polymorphs with stray giant cells, while those around worms with better-preserved morphology (presumably alive) were numerous eosinophils, mononuclears and lymphocytes. The probable significance of this cellular variation is briefly discussed.

It is stressed that filarial nodule should be kept in mind in the differential diagnosis of obscure subcutaneous nodules, particularly in areas endemic or hyperendemic for filariasis. Local itching seems important in these cases.

Animals in the Nile Valley from south of Cairo to Aswan were examined for evidence of leptospiral infections. Serological reactors were detected to Leptospira australis, L. autumnalis, L. bataviae, L. canicola, L. grippotyphosa, L. hebdomadis, L. icterohaemorrhagiae, L. malaya, and L. zanoni in 41 of 416 wild animals. Sera of domestic animals collected at abattoirs included reactors to L. autumnalis, L. bataviae, L. canicola, L. grippotyphosa, L. icterohaemorrhagiae, and L. malaya. Two isolations of L. grippotyphosa were made from the house mouse Mus musculus.

Yeast- and mycelial-phase cells of Blastomyces dermatitidis were compared with respect to their capacity for invading the chorioallantoic (CA) membrane of embryonated chick eggs. Experiments were conducted at 31°C and at 37°C.

At 37°C, B. dermatitidis yeast cells penetrated into the mesoderm where they proliferated and produced microabscesses. Mycelial-phase cells inoculated on the CA membrane of embryos maintained at 31°C were confined to the ectoderm so long as the embryo remained viable and the integrity of the CA membrane was maintained.

The degree of initial exudative response to mycelial-phase cells was less than that noted with yeast. This difference in the degree of exudative reaction was particularly evident in experiments conducted at 31°C.

In experiments conducted at 37°C, mycelialphase cells began to convert to the yeast form within 24 hours after inoculation of CA membranes. The newly formed yeast cells subsequently penetrated into the mesoderm and produced microabscesses. Hyphae which failed to convert to yeast remained confined to the ectoderm and appeared to be undergoing degeneration.

From the work presented here, and a previous report by Baker,1 it appears that in animal tissue with a temperature of 37° to 39°C B. dermatitidis must convert to the yeast phase in order to survive and multiply.

During December 1959 and January 1960 mosquitoes were collected in Fiji for the isolation of arthropod-borne viruses (arboviruses), and sera were collected from men and fowls for arbovirus antibody testing. A total of 3,363 mosquitoes was tested by inoculation into 6-day embryonated hen's eggs, chick cell monolayer tissue cultures and in suckling mice, but no virus strains were isolated.

A small proportion of the fowl sera had hemagglutination inhibiting (HI) antibodies to a group B virus. Of the human sera tested, 40% of 233 had HI antibodies to Japanese encephalitis, 47% of 185 neutralised dengue 1 virus, 25% of 173 neutralised dengue 2 virus and 5% of 85 neutralized M78 virus.

It is considered that the major infecting agent is a virus more closely related to dengue 1 than dengue 2. There is some evidence of infection with a virus closely related to dengue 2 and of infections with a further unidentified group B virus and also a Sindbis-like agent.

During the outbreak of eastern equine encephalomyelitis (EEE) in Jamaica in November and December 1962, there were 9 deaths among 11 patients clinically diagnosed as having EEE. Five of these cases were confirmed by laboratory tests. Of the two recovered patients, one showed a significant rise in EEE antibody titer and the other showed no demonstrable antibody. The presenting features of illness were mainly fever, headache, neck rigidity, paralysis and drowsiness or coma.

Eastern equine encephalomyelitis virus was isolated from man and horses during an outbreak of the disease in Jamaica in November and December, 1962. Viruses were isolated from 4 of 7 human brain tissue specimens and from 3 of 6 equine brain specimens. Histopathological evidence of encephalitis was evident in all the tissues examined.

The pygmy anteater, Cyclopes didactylus dorsalis, is sufficiently susceptible to yellow fever virus to serve as a host experimentally and in nature. It circulates the virus in good titer for a period of 1 to 7 days. Its possible ecological importance is discussed.

The venom of the scorpion Centruroides sculpturatus Ewing has been responsible for more than twice as many deaths in Arizona than the venoms of all other venomous animals combined. Clinical experience indicated that patients stung by this scorpion and given meperidine hydrochloride (Demerol®) consistently experienced a more serious reaction from this venom. The hypothesis that synergism existed between this scorpion venom and Demerol, morphine sulphate, dihydromorphinone hydrochloride (Dilaudid®), codeine phosphate, N-allyl-normorphine hydrochloride (Nalline®) and 1-3-hydroxy-N-allyl-morphinan tartrate (Lorfan®), was tested. Albino rats of the Holtzman/Sprague Dawley strain were used as assay animals and the Thompson-Weil technique was used for obtaining the LD50.

The assays confirmed the clinical observations that these substances act synergistically with the venom. Morphine sulphate, in doses of 50 mg/kg, and Dilaudid, at 20 mg/kg, increased the toxicity 7.14 times, while Demerol, in a dose of 50 mg/kg, produced an increase of 3.57. To the extent employed, the increase was in direct proportion to the size of the dose. It was concluded that the use of these narcotics as therapeutic agents during the height of venenation by this scorpion would be unwise.

Officers. President—Clay G. Huff; President-Elect—Thomas H. Weller; Vice-President—E. Harold Hinman; Secretary-Treasurer—Geoffrey M. Jeffery; Editor—Paul C. Beaver

Councilors. A. Gabaldon; L. E. Rozeboom; C. M. Johnson; W. G. Downs; H. Most; C. B. Philip; L. A. Stauber; J. Oliver-Gonzalez

Minutes of the Annual Council Meeting. The annual business meeting of the Council was held at 7:30 p.m., November 5, with President Huff presiding. All officers and councilors were present with the exception of Drs. Gabaldon, Rozeboom and Johnson. Also in attendance were Drs. William DeWitt, Eli Chernin, Paul Thompson, Benedict Jaskoski, Martin Young, Justin Andrews and Gilbert Otto.

The minutes of the eleventh annual meeting held in Atlanta, Georgia, were approved as published in the Journal for March, 1963.

The President reported briefly on the activities of his office during the year, including the Society's administration of travel grants for approximately 100 individuals to attend the Seventh International Congresses on Tropical Medicine and Malaria in Rio de Janeiro, and his representation of the Society at the 100th anniversary celebration of the National Academy of Sciences.