The American Journal of Tropical Medicine and Hygiene - Volume 17, Issue 3, 1968

I am sure you would agree that modern, high-speed, commercial jet aircraft have figuratively shrunken the globe. In recent years, relatively vast new areas of the earth have been scrutinized by students of the physical and natural sciences. Our colleagues, the virologists, report almost monthly new discoveries such as the Whataroa virus, a new arbovirus isolated in New Zealand, the chikungunya virus, Kyasanur Forest disease, and a host of other unpronounceable agents, diseases, and locations. Yet, we in tropical medicine are not making many really striking discoveries. It may be that parasitologists, having started several hundred years earlier and being more adventuresome, exhausted the field long before the jet era.

In preparation for this Presidential Address, I have studied maps and charts in the hope of discovering a little-known geographic location with a little-known parasite or disease about which I could speak with authority or from experience.

The H strain of P. knowlesi was transmitted through the bites of Anopheles balabacencis balabacensis mosquitoes from monkey to man, from man to man, and from man back to monkey. All attempts to infect man through the bites of infected mosquitoes were successful, one volunteer contracting infection after only a single infective bite. The prepatent periods in man ranged from 9 to 12 days, and in the monkey was 6 days. The infections exhibited a quotidian periodicity, and were characterized by relatively high parasitemia and moderate to severe clinical manifestations.

The significance of this zoonosis as it may affect a program of malaria eradication is discussed.

The ciliated protozoon, Tetrahymena pyriformis W, was used as a test animal for determining the lethal effect of certain antimalarial drugs.

Quinacrine, proguanil, primaquine, and quinine have a definite lethal effect for Tetrahymena. Quinacrine is lethal in amounts as small as 16 µg per ml or less, the other three being somewhat less toxic. Samples of drugs, from different lots of quinacrine and primaquine, yielded results comparable to those originally tested, and samples of primaquine from two different manufacturers yielded similar results. Chloroquine is mainly inhibitory at room temperature, but has some lethal activity when incubated at 37°C for 1 hour before the usual room-temperature incubation.

Eight other antimicrobial agents had little or no activity with the exception of chlortetracycline and minocycline. Chlortetracycline had slight lethal and moderate inhibitory activity for Tetrahymena; minocycline was both a strong lethal and inhibitory agent.

An apparent case of chloroquine-resistant falciparum malaria was reported from eastern coastal Brazil from the state of Espírito Santo some 550 kms northeast of Rio de Janeiro. This constitutes a new endemic area. The patient was successfully treated with a combination of quinine sulfate, sulfadiazine, and pyrimethamine.

Mice infected with Schistosoma mansoni were immunized with a saline-solution extract of adult worms. Mortality in mice so immunized was compared with that in a control group of infected mice treated with saline solution. Mortality in the immunized group was about three times lower than in the nonimmunized mice.

Pulmonary-function studies in 11 early asymptomatic cases of schistosomiasis, before and after treatment with sodium antimony dimercaptosuccinate, suggest that early schistosomiasis may be accompanied by measurable though mild impairment of pulmonary function in the absence of clinical or radiologic evidence of pulmonary involvement.

Investigations on hookworm infections in dogs, cats, and man were carried out in Taiwan during the summer of 1966. Ancylostoma ceylanicum was found in two of eight dogs and in three of 10 cats captured in the area of Taipei. Anthelmintic treatment revealed. A. ceylanicum in two of 12 aborigines and in three of 128 Chinese of the general population. A. braziliense was not found in either man or animals.

A method of fecal examination described by Kato and involving the clearing of a direct fecal smear pressed thin under a glycerin-impregnated cellophane coverslip was evaluated for possible use in quantitative diagnosis of helminth infections. Modifications were described for 1) removing fiber from the fecal sample, 2) uniformly spreading the smear, and 3) preventing over-clearing of the preparation. Optimum time for clearing the smears was found to be about 30 minutes at 35°C, or about 1 hour under openroom conditions.

The thick-smear method was found to be as sensitive as the Bell filtration, zine-surface flotation, and Hoffman sedimentation methods of concentration of feces. Egg-counts for estimation of intestinal nematode and Schistosoma mansoni infections were as reproducible when made by the thick-smear method as by dilution or concentration procedures.

Series of egg-counts made from the same stool and from daily stools indicated that eggs of S. mansoni, as well as those of other worms, are distributed randomly in the feces and are in equal numbers in the outer and inner portions of the stool. Thus egg-counts made by the thick-smear technique appear to be reliable for the quantitative diagnosis of helminth infect ons.

A total of 191 sera collected in Somalia was tested for antibody to Schistosoma haematobium by three serologic tests, to Echinococcus granulosus and filarial antibodies by bentonite flocculation tests, and to Toxoplasma gondii and Entamoeba histolytica by hemagglutination tests.

The prevalence rate of Schistosoma antibodies as determined by the BF, C-L, and FA tests was 59.7%. Serologic tests indicated that hydatid infection does not, at present, appear to be a human problem but a veterinary one. Filarial antibodies were more prevalent in the nomadic group, Toxoplasma antibodies were found in 10% of the people tested, and ameba antibodies in 22%.

The seroepidemiologic studies have added further information on the parasitic status of one small area of Somalia.

The numbers of Shigella in feces of children with clinical shigellosis (Sh. dysenteriae, Sh. flexneri, Sh. boydii, and Sh. sonnei) under both home and hospital conditions ranged from 105 to 108 per gram of wet feces. Children with Sh. sonnei dysentery had a longer convalescence, and feces consistently had greater numbers of Shigella than did patients with Sh. flexneri. Symptomless carriers excreted smaller numbers of Shigella, usually 102.

Among fecal bacteria associated with shigellosis, streptococci, lactobacilli, and bacteroids were generally most numerous. Candida and staphylococci ordinarily were few. The numbers of coliforms, enterococci, and Shigella fluctuated according to no fixed pattern. Coliform organisms were usually in inverse proportion to numbers of Shigella. Lactobacilli and streptococci were relatively rare during acute clinical diarrhea, especially when blood and mucus were present in stools.

In the fall of 1964 a newly observed febrile hemorrhagic disease caused the death of 223 monkeys in the NIH quarantine colony of 1,050 animals. Three Macaca species were affected. The disease affected animals in 16 of 18 rooms housing the colony. The manner of spread of the disease through the colony is not known but several possible ways have been considered. Clinical features of the disease included rapid onset, early fever, mild facial edema, anorexia, adipsia, dehydration, proteinuria, cyanosis, skin petechiae, melena, epistaxis, and occasionally retrobulbar hemorrhages. Therapeutic measures, consisting of broad-spectrum antibiotics, vitamins, forced feeding, and oral or parenteral electrolyte administration, were ineffective. Mortality among infected animals was thought to be 100%. However, experimental-transmission studies indicated that some animals survived clinical illness. A similar outbreak had occurred among rhesus monkeys newly imported to a primate colony in the U.S.S.R. shortly before the NIH outbreak; this suggests a common source for this disease, since both colonies received animals from the same Indian supplier.

Transmission studies with rhesus monkeys established that the disease was contagious between animals within the same and neighboring cages and that the tissues of dying monkeys contained the causative virus agent.

The lesions of simian hemorrhagic fever included capillary-venous hemorrhages in the intestine, lung, nasal mucosa, dermis, spleen, perirenal and lumbar subperitoneum, adrenal gland, liver, and periocular connective tissue. Evidence of vasodilation, stasis, and venous thrombosis often was found in association with the hemorrhages. Shock was therefore suspected as an underlying causative factor. Vascular fragility, blood-clotting defects, and trauma appeared to be associated factors, particularly in connection with certain of the skin petechiae, the hemorrhages under the renal capsule, and those occurring around lung-mite lesions. The direct effects of virus invasion of tissues were not determined. Degenerative changes in the liver, kidney, brain, lymphatic tissue, and bone marrow were believed to be due to blood stasis and hypoxia. The peculiar splenomegaly in simian hemorrhagic fever evidently was caused by follicular hemorrhage and engorgement of the cords with plasma and fibrin.

An epizootic of a previously unknown hemorrhagic fever occurred among Indian rhesus monkeys quarantined at NIH in November 1964. Transmission studies revealed that the disease was due to an infectious agent pathogenic only for monkeys. A virus, designated simian hemorrhagic fever, was isolated in the MA-104 cell line of embryonic rhesus-monkey kidney. Of 13 different cell cultures (primary and continuous) tried, the virus produced CPE only in MA-104 cells, grew without CPE in BS-C-1 cells, and could not be propagated in the other 11 cell cultures. The characteristic CPE began as foci of refractile spindle-shaped cells that remained connected to each other by protoplasmic projections forming a network. Biochemical and Biophysical studies revealed that the virus contains RNA and is less than 50 mµ in size, chloroform-sensitive, pH 3.0-labile and relatively heat-stable. Divalent cations, however, enhanced inactivation at 50°C. The virus reproduced the typical hemorrhagic disease in rhesus monkeys. CF antibodies were demonstrated. No relation could be found between SHF virus and some other known RNA viruses.

Venezuelan encephalomyelitis virus (VEE) was isolated for the first time in Panamá in 1961, the source of the virus being a young boy whose clinical course has been detailed. He succumbed to a fulminating febrile illness without gross clinical signs of encephalomyelitis. Pathologic changes were similar to those reported in experimentally infected guinea pigs and some horses and dogs. Serologic characterization of the isolate permitted differentiation from two recently reported new members of the “VEE complex.” Further evidence for the validity of the source of virus was an outbreak of virologically documented VEE infection in laboratory personnel working with the Panamá virus in the absence of temporal importation of any potential virus-containing materials from outside the country.

A method for detecting and propagating dengue viruses in LLC-MK2 cells has been developed by direct plaquing and by fluid maintenance of inoculated cultures 7 to 14 days before plaquing (delayed plaquing). This procedure was used in support of studies of hemorrhagic fever and has resulted in the recovery of 69 dengue viruses, including all four serotypes. About half of these were detected by delayed plaques when direct plaques were not seen. Most of these dengue strains were inoculated simultaneously into mice and cell cultures. The direct and delayed plaque method was more sensitive and efficient than the use of suckling mice. Comparisons of the direct and delayed plaque method with other methods of recovery of dengue virus are discussed.

Early in the study, occasional difficulty in preparing low-passage cell-culture seed virus of adequate titer was encountered. Consequently, the growth of dengue virus in LLC-MK2 cells was studied. Virus growth was synchronous and cyclic. In order to avoid inadvertent harvesting of virus during eclipse, live cells, rather than cell lysates, were passaged. This has resulted in consistent production of low-passage seed-virus suspensions.

A virus isolated from Aedes abserratus collected in Simsbury, Connecticut, was shown in complement-fixation tests to belong to the California group of arboviruses. The source mosquitoes were taken about 1 month after the species' first appearance in light-trap collections in the course of an ecologic study of the spring Aedes.

Artificial resting boxes (12 × 18 × 30 inches) were used to collect Culiseta melanura in a hammock near Vero Beach, Florida. These boxes provided an easy and effective method to obtain sizable numbers of C. melanura as well as some other mosquitoes. About 15% of all the females collected were blood-engorged.

The use of cloth collecting bags inside the boxes saved time and simplified collecting without reducing the size of the collections.

The boxes attracted more mosquitoes 1) when placed in less densely vegetated areas, 2) when the entrance faced east rather than west, 3) when the height of the dark box entrance was increased from 6 to 12 inches, and 4) when the apparent size of the dark entrance was increased by the addition of a large concave frame around the opening.

Most C. melanura entered the boxes before 8:30 a.m., but some flight activity was evident during most of the day. A higher proportion of the individuals entering after 9:00 a.m. were females, and more of these females contained blood than did those entering earlier. More C. melanura left than entered the boxes during the day. The optimum collection time appears to be influenced by the weather conditions.

Aedes aegypti females were fed through a membrane on Plasmodium gallinaceum-infected red blood cells suspended in whole chicken serum, serum fractions, or saline solution. The relative effect of the ingested host proteins on the development of the parasites in the mosquitoes was determined by counting the oöcysts on the guts of the mosquitoes after a 6-day incubation period. The relative effectiveness of the test materials was as follows. A protein containing both globulin and albumin fractions was about equal to whole serum. Chick serum albumin, fraction V, was inferior to whole serum, but superior to saline solution. A protein fraction containing the globulin but not albumin was comparable to saline solution.

The results of these experiments suggest that albumin may be the most important single component of vertebrate blood serum that supports growth of the oöcysts of malaria parasites in susceptible mosquitoes. However, for maximum growth the total protein of the serum must be present.

Hospitalized patients with various diseases and taking various medications were surveyed for their attractiveness to mosquitoes by a mosquito-probing technique. No drug was found that induced unattractiveness, and no disease was associated with unattractiveness, with the possible exception of untreated myxedema. Vitamins, expecially B1, in biting and probing tests were found inactive systemic mosquito repellents.

A new analytical procedure for the assay of DDS was based upon extraction into organic solvents and measurement of fluorescence in anhydrous ethyl acetate. Men receiving single 100-mg oral doses of DDS showed peak plasma levels of 1.1 to 1.5 µg per ml in 2 to 4 hours; the levels then dropped to half-values in 20.6 hours, and to a few millimicrograms per ml by the 5th day. Intramuscular doses of DADDS administered in an oil vehicle produced peak plasma levels of about 0.06 µg per ml in 6 days, and “plateau” levels of 0.035 to 0.030 µg per ml within 2 weeks. This level was maintained for about 60 days after dose, and dropped slowly thereafter with an apparent biological half-life of 42.6 days. The decrease in plasma levels occurred some 50-fold more slowly with DADDS than with orally administered DDS. The urinary excretion of “total” DDS ran parallel to the blood levels in both studies; it accounted for 68% of the oral dose of DDS and about 54% of the intramuscular dose of DADDS.

The Xavante Indians of the Brazilian state of Mato Grosso as a group were found to have 1) high mean plasma uric-acid levels, 2) low mean plasma cholesterol values, 3) high total plasma proteins, due to elevated γ-globulin fractions, 4) plasma-protein-bound iodines and iron values within the accepted norms, 5) a high frequency of persons with positive tests for the “rheumatoid factor,” 6) marked eosinophilia, and 7) a high frequency of stools positive for the ova of Ascaris, larvae of Strongyloides, and cysts of Entamoeba histolytica. Three of 53 “casual” urine specimens subjected to chromatography were characterized by elevations in specific amino acids, possibly indicative of a genetic carrier status.

Varying numbers of Xavante Indians from two villages in the state of Mato Grosso in Brazil were tested for immunologic status with respect to various diseases and organisms. Among the findings of note were:

• 1.  Positive skin tests to the histoplasmin antigen were encountered in 42.7% of those tested, but there were no certain positives for tuberculin or coccidioimycin.
• 2.  All persons investigated gave positive tests for antibodies to Toxoplasma, usually in high titer.
• 3.  Of those tested, 62% had antibodies to malaria antigens, usually in intermediate titers.
• 4.  There was no serologic evidence (in a small series) for treponemal infections.
• 5.  Between 30 and 80% of those tested, depending on the Salmonella subtype, had antibodies to Salmonella representative of groups A, B, C, and D.
• 6.  Of those tested, 58% were found to have antibodies to Bordetella pertussis.
• 7.  The distribution of titers to three streptococcal antigens suggests moderate contact with this pathogen.
• 8.  Between 71 and 95% of subjects, depending on the specific type, had antibodies to poliomyelitis types I, II, and III.
• 9.  Antibodies to measles were found in 89% of a small series.
• 10.  The results of tests for antibodies against 23 arboviruses isolated in Brazil suggest extensive exposure to the Mayaro and Ilhéus viruses, and lesser exposure to a number of others, including yellow fever.

Although these findings constitute only a beginning in defining the antibody profile among the Xavante, it is clear that this apparently healthy population has been exposed to a wide variety of what would ordinarily be termed pathogens.

Progress in Medical Virology, Volume 9, edited by J. L. Melnick, Houston, Texas. xiv + 496 pages, illustrated. S. Karger Ag Basel, New York. (Distributed in USA by Albert J. Phiebig, P. O. Box 352, White Plains, New York 10602.) 1967. $21.10.

The Ecology of Malnutrition in Northern Africa, Libya, Tunisia, Algeria, Morocco, Spanish Sahara, and Ifni, Mauritania. Studies in Medical Geography, Volume 7, by Jacques M. May, M.D. xv + 275 pages, illustrated. Hafner Publishing Company. New York and London. 1967. $11.50.

Evaluation of Drugs for Tropical Diseases, Proceedings of a Symposium at the Royal Society of Medicine, London, 17th February, 1967, edited by C. Wilcocks and E. L. Harris. ix + 95 pages, illustrated. Association of Medical Advisors in the Pharmaceutical Industry, London. 1967. 22/6d.

The Biology of the Striped Skunk, by B. J. Verts. vii + 218 pages, illustrated. University of Illinois Press, Urbana, Chicago, and London. 1967. $7.95.

This Johns Hopkin's Monograph in International Health describes the working conditions of the physician in Indian rural health centers. The conditions reported reflect the opinions of physicians and five other professional groups involved in determining health center and medical education policy. The latter include district level administrators, senior health administrators and policymakers, state legislators, social and preventive medicine teachers and clinical teachers.

Research objectives described by the authors are two-fold:

• 1.  “To determine the opinions of selected groups responsible for directing health center activities and educating physicians about:
  • a.  actual working of health centers
  • b.  primary health center doctor's role and his problems
  • c.  problems in recruiting and training doctors for rural health center services”, and
• 2.  To identify problems in present administrative patterns of health services and to suggest alternatives for administrative reorganization.

The authors emphasize that “the aim of this study was not to examine directly the present operation of health centers, but to seek opinions of various categories of persons who should know most about health center work and to identify the major discrepancies in their group opinions”.

The author of this monograph on cholera has had 40 years of experience with all phases of cholera control and treatment.

Cholera apparently evolved in ancient times in the Bengal area of India, which is now East Pakistan and West Bengal Province of India. It remained endemic for centuries except for some spread to China, presumably by overland trade routes.

There have been six pandemics of cholera since 1817. Modern methods of transportation had to be developed before the infecting agent could travel over all continents. Robert Koch and his associates isolated the cholera vibrio during the fifth epidemic (1881–1896).

All of the six pandemics were caused by the classic vibrio, Vibrio cholerae. The seventh pandemic began in Sulavesi (Celebes) in 1961 and is still spreading. This current pandemic stimulated the production of this monograph because this epidemic is not caused by classic cholera vibrio, V. cholerae, but by V. cholerae biotype El Tor.

In rather informal but substantial style, Dr. Baker and Dr. Perlman have drawn a quantitative picture of the present and projected supply and demand of health personnel and facilities in the small but densely populated country of Taiwan. Their surveys are well defined, tabulated, and discussed. They include: an island-wide household survey of personal expenditures; a census of health workers; a joint medical-school entrance examination substudy; a student-attitude survey; and a medical-training institutions survey.

In their discussion, the authors clearly indicate the problems of obtaining accurate income-expenditure data, and point out some of the means by which concerned researchers can overcome the lack of reliable official data in their own survey systems.

The authors employ the multisort analysis of demographic factors contributing to present demand for health services, as a valuable tool in more accurate projection of demand shifts resulting from shifts in population characteristics as well as growth in the next 20 years.

This first of three volumes on quality control in the food industry was designed to cover aspects which are applicable to all branches of the food industry. The second and third volumes will be devoted to specific ingredients or products.

The first section on the organization for quality control by J Hawthorn considers the needs and reasons for quality control as well as the organization of the program and personnel required to handle a program. The approach of considering the problems arising in the quality control of a hypothetical food product made from acorns is quite refreshing.

The consideration of the health problems is divided into the logically separated chemical and microbiological aspects. The first of these was covered by Alastair C. Fraser while the latter was handled by Betty Hobbs. Under the chemical aspects, the approach of balancing of benefits and risks is introduced along with the factors that determined the potential hazards or safety.