The American Journal of Tropical Medicine and Hygiene - Volume 14, Issue 1, January 1965

A detailed description is given of the field and recording methods used in 12-month Synoptic Studies of some problem and comparison malariaeradication areas in El Salvador, with the hope that it may serve as a guide to a simple, inexpensive, and efficiently productive operational approach to the evaluation of factors underlying the persistence of malaria so that appropriate remedial measures may be instituted.

In six bimonthly 2-week visits to each of eight areas data were gathered by two teams of epidemiological aides under the direction of an epidemiologist and a medical entomologist, utilizing about 14 different procedures. Prompt tabulation and summarization enabled concurrent evaluation of the field work. Epidemiological data included daily minimum-maximum temperatures and morning and evening relative humidities; repeated censuses of houses to include new and temporary shelters and spraying history; quantitative survey of sprayable indoor surfaces (relative amounts of openings, impervious and porous materials); repeated censuses of inhabitants and malaria prevalence (by age and sex) through 20% random parasitemia surveys and active case detection by the team and passive case detection by the malaria notification posts and investigation and classification of malaria cases (autochthonous vs. imported). Entomological studies (involving two-thirds of available man-hours exclusive of travel) consisted of collections by aspirator of adult anophelines on inside walls from 8 a.m.–noon, on human bait in and around houses from 6:30–8:30 p.m. and 6 p.m.–6 a.m., and in and around cattle corrals at night (to determine activity and relative abundance of species); limited sampling of larvae locally present; and DDT-susceptibility and excito-repellency tests of Anopheles albimanus. Data previously gathered by the malaria eradication service and in an intensive PAHO field study of two coastal villages facilitated the planning of the studies.

A. albimanus comprised about 98% of the adult and 65% of the larval anophelines collected. Its biting activity was usually, but not always, highest in the first half of the rainy season and was not highly correlated with malaria incidence. Biting occurred both indoors and, somewhat more frequently, outdoors, and this species also predominated in cattle-corral collections. A. pseudopunctipennis comprised 35% of the larvae collected, but adults of this and five other species were found only occasionally. No taxonomic studies were undertaken. A. albimanus was highly resistant to DDT in four of the study areas and highly, if not quite completely, susceptible in the other four, without significant seasonal variation. All populations exhibited marked excito-repellency to DDT, with a suggestion that two resistant populations may be losing their excito-repellency (which would render DDT useless).

Six Malariological Zones can be recognized in El Salvador (total area 8164 sq. miles, population originally at risk 1,820,000 with A. albimanus the only vector), heavy, moderate or minimal transmission being each associated with either DDT-resistance or -susceptibility: 1. heavy with DDT-resistance; 2. heavy with DDT-susceptibility (in the region in which mass administration of chloroquine-primaquine has minimized transmission); 3. moderate with DDT-resistance; 4. moderate with DDT-susceptibility (assumed to be present but not encountered); 5. minimal with DDT-resistance; and 6. minimal with DDT-susceptibility.

Suspension of DDT-spraying is recommended because its limited value does not now justify its high cost and old residues are still exerting appreciable effect. Mass administration of sugarcoated chloroquine-primaquine pills should be extended to the entire problem area, fortnightly in Zones 1 and 2; initially monthly in Zone 3; and expectantly in Zones 4, 5, and 6. Provision should be made to control epidemic outbreaks by appropriate means.

The authors, in collaboration with the staff of CNEP, Mexico, carried out an investigation of persistent malaria transmission in a coastal area of the State of Oaxaca from May through August 1962. The area had been thoroughly sprayed with DDT for five years, and spraying continues. In a detailed survey of malaria cases and housing in ten villages, it was found that malaria-positive houses tended to be in isolated positions, to be smaller than average, to have more inhabitants and to show a greater discontinuity in, and lack of, walls than the negative ones.

A study of malaria cases detected by various methods among 29,216 inhabitants of the area over a period of 30 months showed an annual incidence (including relapses) of 1.32% in this population. The incidence was substantially higher in the second half of each year than in the first, and there was a general upward trend between 1960 and 1962. DDT was applied at average intervals of six months, but spraying within the area was distributed randomly through the year. Counting of the cases detected when the DDT deposits were less and more than three months old, respectively, showed an increase from 2.46% to 3.49% in the proportion of slides positive when the insecticide deposits were old, although only very small amounts of unsprayed interior surface were then present.

The vector anophelines found biting man were Anopheles pseudopunctipennis and A. albimanus. Both bit human baits freely outside and inside the sprayed houses. Although the relative incidence of indoor biting was somewhat reduced in the weeks following spraying, the habit of the people of sleeping nearly always indoors meant that the bulk of contact between them and the vectors must occur within the houses. The vectors were found susceptible to DDT (with some indication of incipient resistance in A. albimanus), while the small numbers caught in window-traps were shown to leave the houses soon after biting and to have a low 24-hour mortality rate thereafter. The two vectors are considered to be highly irritable by DDT and to escape easily from the treated houses. During the investigation it was observed that malaria transmission could take place in spite of low vector densities.

Natural emetine, synthetic 2-dehydroemetine or the corresponding 14C-labeled compounds were injected intraperitoneally into guinea pigs in the form of the dihydrochloride. The unlabeled drugs were determined spectrofluorometrically, and the 14C-labeled compounds by combustion and liquid scintillation counting. These determinations show that:

Dehydroemetine is eliminated more rapidly from each individual organ than is emetine.

Dehydroemetine disappears relatively more quickly from the heart than from the liver, whereas the reverse is true of emetine. This may in some way be related to the equal therapeutic activity and lower cardiotoxicity of dehydroemetine compared with emetine.

After an intraperitoneal injection of 14C-labeled emetine or dehydroemetine, 95% of the injected radioactivity was recovered in the feces while only 5% appeared in the urine.

Fluorescent antibody technics were used to determine the localization and distribution of Schistosoma mansoni antigen in tissue cells, the presence of circulating antibody, and the sites of antibody production or in vivo antigen-antibody combination. The experiments were performed in mice after a primary infection with cercariae, after several challenges, and after antigen stimulation and challenge. Evidence of the presence of circulating antibody was first observed at 20 days in the inhibition fluorescent antibody test, at 25 days in the indirect fluorescent antibody test, at 42 days with the cercarial fluorescent antibody test, and at 47 days in the Cercarienhullen reaction.

Sites of antibody production or in vivo antigen-antibody combination were observed in inflammatory cells of the portal tracts, especially those along the smaller arteries, and in granulomas and isolated cells in the parenchyma of the liver; in the perivascular tissue cells, isolated parenchymal cells and granulomas of the lungs; and in cells in the center of the follicles and of perivascular infiltration in the spleen and lymph nodes.

The sites of antigen deposition after a single exposure were the perivascular inflammatory infiltrate and histiocytes in the parenchyma of the liver and lungs, the granulomas of the liver, and the neutrophils in the sinuses and the perivascular cells in the spleen. In the reexposed and antigen-stimulated groups, the same areas were positive for antigen, and in addition, antigen was detected in the endothelium of the blood vessels in the lung and some cells in the lymph nodes.

The histologic alterations in mice infected with Schistosoma mansoni and in non-infected mice having a common circulation with infected animals were studied by means of the parabiotic technique. The experiment involved 23 exposed + unexposed pairs and 12 unexposed control pairs. The animals were sacrificed at intervals up to the seventeenth week of infection and multiple histologic features were studied.

The predominant change in the animals not directly exposed to the parasite consisted of variable degrees of lymphoreticular activation. In the lung this was manifest as prominent perivascular round cell infiltration. In the liver changes were limited to Kupffer cell hyperplasia and prominence and slight inconstant increase in portal cellularity. In the spleen lymphoreticular activation was expressed by increase in follicular size and enhancement of germinal center activity. While similar changes were noted in the control animals as a manifestation of the parabiotic state, in general, the response was less than that seen in the experimental animals.

The relationship of these changes to an immunological response of the delayed sensitivity type is discussed. The possibility is considered that alterations not seen in the unexposed parabionts are local expressions of antigen-antibody interaction or are caused by other non-transmissible factors.

Hematemesis from esophago-gastric varices follows a definite periodicity correlated with high environmental temperature and perhaps with increased partial pressure of carbon dioxide.

Samples of sausages and frankfurters collected in 176 stores in Guatemala City (in a 20% random sample of 3,758 food establishments) were examined for the presence and viability of cysticerci. Cysticercus cellulosae (1–45 per sample) was found in 6 percent of 99 pork sausage, 6.5 percent of 107 Spanish-type sausage, and none of the 6 cocktail sausage or 77 frankfurter samples. The cysticerci were unencapsulated and none of 82 incubated in saline-bile mixture evaginated. C. bovis would not be expected to survive or to be detectable in beef sausages. Three types of tests (evagination in saline-bile mixture and in pure bile, and activity of flame cells) with cysticerci in experimentally prepared pork and Spanish-type sausage equally indicated a rapid loss of viability, as none survived longer than 3 days. Nevertheless, the presence of the cysticerci in processed meat indicates poor rural environmental sanitation, deficient inspection of meat, and clandestine butchering of hogs.

There was found at autopsy in the right heart of a 40-year-old, diabetic, female resident of New Orleans, a worm 21 cm in length and identified as Dirofilaria immitis. A similar case was reported from New Orleans in 1941.

Larval nematodes more than 2 centimeters in length were found in eosinophilic granulomas in the stomach of two patients suffering from acute abdominal symptoms. On the basis of morphological comparison with worms identified as immature Anisakis sp. from the sperm whale, the larva of one case was identified as Anisakis sp., and that of the other was identified as a different but closely related species. Striking features of the larvae were large Y-shaped lateral chords extending into the body cavity, and numerous, high columnar epithelial cells forming the wall of the intestine as well as a large gland-like organ along the esophagus and upper intestine.

The infections presumably were acquired by eating raw fish, a custom that is widespread among the Japanese. It is expected that similar cases may be found among Japanese patients presenting with acute abdominal symptoms.

Approximately 16,300 rodent, lagomorph, herbivore, carnivore and bird wildlife specimens and their ectoparasites, collected between 1957 and 1962, were routinely examined for the incidence of certain endemic pathogenic organisms. These pathogens were Pasteurella tularensis, P. pestis, Brucella spp., Bacillus anthracis, Coccidioides immitis, Coxiella burnetii, and Rickettsia rickettsii. The sera of the original specimens, as well as that of tissue- and ectoparasite-injected indicator guinea pigs, were examined for complement fixation and/or agglutination antibodies, as applicable. Appropriate isolation procedures were carried out for each organism when evidence indicated its presence.

In the survey 1,367 specimens consisting of 19 species were found to be seropositive for Q fever; 1,951 specimens of 23 species were positive for Rocky Mountain spotted fever; 28 serum samples from 6 species contained Brucella agglutinins; and 40 specimens of 11 species had P. tularensis agglutinins. Ninety-one isolations of C. burnetii were made from animal tissues and 23 from ectoparasites. Four isolations of Br. neotomae were made from tissues, and isolations of P. tularensis were made ten times from tissues and twice from ticks. P. pestis was isolated once from tissues. Numerous isolates of R. rickettsii or of a related rickettsia were made, but none having the virulence of classical R. rickettsii were found. There was no evidence of viable B. anthracis or C. immitis in the specimens examined.

A simple medium for the collection and transport of stool or rectal swabs was tested in an area where diarrheas are endemic. In most instances, enteric pathogens survived 7 days or longer following inoculation of the medium. Interference by non-pathogenic bacteria commonly found in the stool was not apparent.

The medium consists of sodium thioglycollate, Na2HPO4, CaCl2, NaCl, and agar in demineralized distilled water, and is adjusted to pH 8.4. It is easily and cheaply prepared, does not need refrigeration prior to use or incubation following inoculation, and has a small space requirement. The semi-solid nature of the medium eliminates the leakage or spillage often associated with fluid-collecting media. Swabs for use with the medium are prepared by dipping them into hot Sorenson's buffer, pH 8.1, followed by sterilization and drying.

It was concluded that the medium provides a practical, effective means for the collection and transport of fecal material for subsequent bacteriologic examination.

A nasal granuloma caused by Entomophthora coronata is reported from an 11-year-old boy residing on Grand Cayman, an island near Jamaica. This is the first case of phycomycosis reported from Jamaica. It is also the first report of a human infection caused by E. coronata.

A virus new to Middle America, the Chagres virus, was isolated in Panama from the blood of a patient who was infected with the virus. It was found to be pathogenic for suckling and weanling mice and to be sensitive to sodium desoxycholate. A hemagglutinin was demonstrated which exhibited unusual characteristics under certain conditions. No relationship of this virus to 49 other arboviruses could be demonstrated by means of the complement-fixation test. The presence of neutralizing antibody in human sera from one Panamanian community was demonstrated.

This report describes some of the properties of Chagres virus, a new human arbovirus from the American tropics. It was found to be antigenically related to Icoaraci virus2 and to the prototype Naples sandfly fever virus.

Isolation of a new entity, Cotia virus, from sentinel mice, in São Paulo State, Brazil, is described. The agent is pathogenic for baby mice and it is inactivated by sodium desoxycholate. It is proposed for inclusion in the arbovirus group.

Fourth-instar larvae of Aedes aegypti were infected with four group A (eastern equine encephalitis, western equine encephalitis, Venezuelan equine encephalitis and Sindbis) and four group B arboviruses (West Nile, St. Louis encephalitis, Japanese B encephalitis and dengue). Larvae of Culex molestus were infected with EEE and WN viruses. The imagoes of infected larvae were able to transmit these viruses by bite to suitable experimental animals. Ability to transmit WN virus was retained to the end of a 45-day test period.

The threshold doses required to infect A. aegypti larvae with viruses belonging to group A were higher than for viruses belonging to group B.

No virus could be detected in larvae 24 hours following exposure to WN virus. Virus was later detected first in the head and alimentary tract, and before pupation it was present in all parts of the larvae. The virus continued to multiply in the pupae and reached a peak titer in the adults on the day of emergence or a day thereafter.

Mosquitoes infected as larvae transmitted WN virus when they fed for the first time between the fourth and fifth day after emergence. It is questionable whether this represents the actual extrinsic incubation period because the levels of virus in the salivary glands were theoretically sufficient to elicit transmission even earlier.

The rates of transmission by A. aegypti infected in the larval stage ranged between 22% and 33% when the larvae were exposed to a suspension containing 3 × 107 to 3 × 108 LD50 of WN virus per ml.

The virus content of the ovaries, irrespective of the age of mosquitoes, was always low and in some cases not detectable.

A comparison was made between the reproductive potential of the selected dieldrin-resistant El Salvador and the dieldrin-susceptible Panama populations of Anopheles albimanus. The fecundity rate in both was about the same, but the fertility rate was slightly higher for the El Salvador females.

Sexual activity of the two populations was determined by single and multiple choice mating experiments. In general, both males and females of the resistant population from El Salvador appeared to be more aggressive than were the adults of the Panama colony.

This study suggests that the development of dieldrin resistance in the El Salvador population was not accompanied by a loss in competitive advantage through reduced reproductive potential.

Over a three-year period, 10,229 blood-engorged Culex tarsalis were collected in rural areas of Kern County, California. These blood meals were identified with precipitating antisera prepared in birds and rabbits. C. tarsalis had a variable feeding pattern, showing a preference for passerine birds at all seasons but most pronounced in the winter. There was a significant increase in feedings on doves and mammals at the height of the summer. The feeding patterns reflected the abundance of different animal species in proximity to the collecting sites. Collections of C. tarsalis from habitats believed to favor feeding on man or rodents failed to yield any feedings on these hosts. Only six feedings on rodents and three on reptiles were detected. The feeding habits of C. tarsalis in Kern County would indicate that passerine birds and doves are the most likely hosts of Western equine and St. Louis encephalitis viruses.

Dynamic Pathology, Structural and Functional Mechanisms of Disease, by Maurice M. Black, M.D., Professor of Experimental Pathology, New York Medical College, New York, N. Y.; Attending Pathologist, Flower and Fifth Avenue Hospitals, New York, N. Y., and Bernard M. Wagner, M.D., Professor and Chairman, Department of Pathology, New York Medical College, New York, N. Y.; Pathologist, Flower and Fifth Avenue Hospitals, New York, N. Y. 296 pages, illustrated. The C. V. Mosby Co., St. Louis. 1964. $8.00.

How to Conquer Nervous Stomach Trouble, by Joseph F. Montague, M.D., Fellow American Medical Association, Fellow International College of Surgeons, Fellow American Public Health Association, Royal Society of Health (London), Fellow American Geriatric Society, Fellow New York Pathological Society, Director of the Medical Writers' Institute. viii + 310 pages, illustrated. Argonaut Books, Larchmont, N. Y. 1964. $5.00.

Parasitology, The Biology of Animal Parasites,by Elmer R. Noble, Ph.D., Professor of Zoology,University of California, Santa Barbara, California, and Glenn A. Noble, Ph.D., Head,Biological Sciences Department, California State Polytechnic College, San Luis Obispo, California.

This book edited by Goldin and Hawking has fifteen contributors. Doctor Frank Hawking of the National Institute for Medical Research at Mill Hill, London, England, has just completed in association with Doctor R. J. Schnitzer a three-volume series on Experimental Chemotherapy also published by Academic Press. (See Am. J. Trop. Med. & Hyg., 12: 834; 13: 903; 14: 179.) The contributors to these volumes are different and in many respects the contents are quite different. This volume, as the title indicates, is concerned with recent advances in chemotherapy. Among the subjects discussed are: Quantitative Concepts in the Clinical Study of Drugs, Mechanism of Action of Phenanthridine and Aminoquinaldine Trypanocides, Chemoprophylaxis and Chemotherapy of Viral Diseases, The Vinca Alkaloids, Cell Culture and Cancer Chemotherapy, and Immuno-reactions in Antiparasitic Chemotherapy. The papers are well written and are supported by good bibliographies.The book should be useful not only to those engaged in research in chemotherapy but also to microbiologists in general and even more to those who are unable to follow closely the rapidly developing literature on chemotherapy.

The author, Doctor Norman-Taylor, has been almost continuously engaged in the compilation and editing of this comprehensive bibliography on medical and paramedical research in the South Pacific from 1949, when the South Pacific Commission was founded, through December 1963. Each reference (pp. 1–296) includes author(s), subject, publication source and year. Classification of subjects is by library code numbers (610-618.97). There follows an Alphabetical Index of References to Health by subject, with its code, so that no difficulty is experienced in locating reference category groups, viz., Arbor-virus fevers—614.529; parasitic diseases—614.55. In addition, there are an Index of Authors and an Alphabetical List of Journals from which the references have been obtained.

The volume is offset printed, approximately 8″ by 10″, in hard paper cover. Doctor Norman-Taylor has rendered a valuable service for all persons desiring source information on medical research in the South Pacific.

This volume completes the series concerned with chemotherapy of infectious diseases. Volume III was written by twenty-one contributors from many parts of the world. The volume completes the presentations on chemotherapy of bacterial diseases and includes chemotherapy of fungal, rickettsial and viral infections. Among the subjects discussed are the penicillins, mode of actions of streptomycin, the tetracyclines and their mode of action, Chloramphenicol, Macrolides and Chemotherapy of Fungal, Rickettsial and Viral Diseases. This book although about 600 pages in length is not complete but is an excellent source of information for both microbiologists, students and clinicians. There is a good bibliography appended to each chapter and the index is good. The book is a good one on the subject.

Persons concerned with or interested in the economy and health of the inhabitants of tropical countries have looked forward in recent years to each triennial publication of the Proceedings of the Industrial Council for Tropical Medicine. Considering this report and the four earlier ones, the present reviewer is impressed with the variety of topics presented and the diversity of authors, including those with practical experience in tropical countries and those recognized as world leaders. Subjects presented at the Fifth Conference, October 29–31, 1963, and published in this volume include: economic aspects of health in the tropics, control of environmental health hazards in Firestone rubber plantation (Liberia) and health aspects of the Volta River project (Ghana); vaccination against trachoma (Saudi Arabia), prospects for vaccination against newer respiratory viruses, immunization against poliomyelitis and smallpox in the tropics, immunization by jet injection, and advances in knowledge concerning rubella; therapy for superficial mycoses; epidemiologic and economic aspects of onchocerciasis; progress in malaria eradication (British Guiana); tuberculosis in the tropics, heart disease due to Trypanosoma cruzi infection (Venezuela), and toxicologic hazards resulting from use of pesticides.

Readers of the American Journal of Tropical Medicine and Hygiene who are interested in skin diseases are sure to find much useful material in this book. In one volume, the authors have compiled an encyclopedic collection of valuable information about skin diseases of animals. An examination of the references reveals the extent to which veterinary medical literature has been searched and critically evaluated. The work contains almost 3000 references taken from 11 different languages.

The skin diseases of domestic animals in North America and Europe are given primary consideration in the book, but readers of this Journal will find many descriptions of dermatoses occurring in other parts of the world. There are references to Glanders in China and Africa, Foot and Mouth Disease in Mexico, Streptothricosis in Northern Rhodesia and Australia, Phycomycosis in horses in Indonesia, Black Piedra in monkeys of South America, Parakeratosis of pigs in Australia and Madagascar, and Parakeratosis of cattle in British Guiana.