The American Journal of Tropical Medicine and Hygiene - Volume 39, Issue 1, July 1988

The Councilors of the Society decided at the Los Angeles meeting that the JOURNAL would be published on a monthly basis and that the first issue would be July of 1988. This is that issue, bringing to fruition an intent voiced by many since the first appearance of the American Journal of Tropical Medicine in January, 1921.

The foreword of that initial issue reads in part:

“The reason for the existence of this new JOURNAL can be summed up in two statements: specialization is necessary for progress, and self expression is necessary for specialists. Specialization in tropical diseases has had a notable place in the medical work of our country and has been responsible for progress along many lines, not the least part of which has been due to the personnel of the Government Services. The story, however, is a continued one. Many diseases in the southern and border states still require the attention of specialists in tropical diseases.

Possible factors contributing to the development of cerebral malaria were discussed based on pathological changes in Burmese patients who died of cerebral malaria. Blockage of cerebral capillaries by Plasmodium falciparum infected erythrocytes appeared to be the principal cause of cerebral malaria. From electron microscopic results, it was concluded that knobs on infected erythrocytes acted as focal junctions which mediated adhesion to endothelial cells. The knobs are, therefore, important contributors to the blockage of the capillary lumen and ensuing pathological changes in cerebral tissues. Host cell molecules such as OKM5 and thrombospondin may function as endothelial cell surface receptors for the attachment of knobs of P. falciparum infected erythrocytes. Immunological events might also play a role in the pathogenesis of cerebral malaria. This was suggested by the presence of IgG, IgM, P. falciparum antigens, and knob proteins in the cerebral capillaries of the people with cerebral malaria. It will be important to assess the candidate malaria vaccines now in development not only for their efficacy in reducing parasitemia but for effects they may have on the sequestration of infected erythrocytes in the brain.

A cross-sectional seroepidemiological survey seeking hyperreactive malarial splenomegaly was carried out in isolated Yanomami hamlets in Amazonas Territory in Venezuela. All 110 inhabitants > 1 year of age were evaluated clinically and 98 were studied immunologically.

The spleen index for individuals > 10 years of age was 44%. Only 3 patients had Plasmodium spp. on thick blood smears. All had serological evidence of infection with Plasmodium falciparum and P. vivax. Twenty-three patients were considered to show hyperreactive malarial splenomegaly.

Clinical manifestations of the syndrome did not differ from those described in other parts of the world.

Verapamil, a calcium antagonist, has recently been shown to reverse chloroquine resistance in malarial parasites in vitro. We report the first ultrastructural morphological changes associated with this phenomenon using chloroquine-sensitive and -resistant clones of Plasmodium falciparum. While the administration of 6.3 × 10-8 M chloroquine had little morphological effect on the chloroquine-resistant strain, the combination of chloroquine and verapamil resulted in typical chloroquine-related food vacuolar swelling with increased amounts of granular matrix. Secondary morphological changes included degeneration of nuclei, mitochondria, and other organelles. These effects appeared similar to those in the chloroquine-sensitive strain of P. falciparum treated with chloroquine alone or with the chloroquine/verapamil combination. Furthermore mild food vacuolar changes were seen in a small number of parasites (from both chloroquine-sensitive and -resistant groups) exposed to high concentrations (1 × 10-4 M) of verapamil alone.

Ninety-five samples of peripheral blood from patients with Plasmodium falciparum malaria in southwest Saudi Arabia were examined by Giemsa staining and darkfield microscopy under flow condition. Eighty-four samples contained trophozoites (ring forms) only and 11 samples contained gametocytes and trophozoites. Two patterns of pigmentation were observed in the trophozoite-containing samples: 48 (57%) contained trophozoites in which no pigment could be detected, 32 (38%) contained trophozoites with clearly detectable pigment, and 4 (5%) contained both pigmented and nonpigmented forms. Trophozoite pigmentation did not correlate with percent parasitemia or age or sex of the patients. These results indicate that microscopically observable pigment accumulation in trophozoites of P. falciparum is not required during the asexual multiplication cycle. Pigment accumulation may be triggered later in infection, perhaps as a feature of the differentiation process leading to the formation of gametocytes.

Antibodies against gametes of the malarial parasite inhibit the development of the parasite in the mosquito and curtail the transmission of malaria. We now report that a monoclonal antibody against gametes of the human malaria pathogen Plasmodium vivax and antibodies induced during natural infections of P. vivax in humans which suppress infectivity of the parasites to the vector at high concentrations can, at lower concentrations, have the opposite effect and enhance the level of malaria infection in the mosquitoes. Infectivity enhancing effects of up to 12-fold were demonstrated when a transmission blocking monoclonal antibody and immune human sera were diluted, in some undiluted immune human sera, and in the sera of vivax malaria patients during convalescence after drug cure.

Blood specimens to be tested for the presence of Plasmodium falciparum using specific DNA probes can be stored as high salt lysates (HSL) without refrigeration. The lysates are prepared from 100 µl blood samples by a simple 3-step procedure using 2 volumes of H2O to lyse the erythrocytes (step I), 1 volume of a detergent/EDTA mix to lyse the parasites (step II), followed by the addition of 1 volume cesium trifluoroacetate (CsTFA) (step III). The parasite DNA was found to be undegraded, as shown by the unaltered pattern of repetitive sequences obtained after storage of up to 1 month at 37°C, due to the inhibition of DNA degrading enzymes by the cesium salt. The bulk of protein can be removed from the samples by a 1-step precipitation. The addition of 0.3 volumes of a mixture of ethanol: chloroform: isoamyl alcohol (2.5:1:0.04 v/v) precipitates >90% of the proteins from the lysates, leaving >86% of the parasite DNA in the supernatant. The reduced protein content of the samples, when applied to solid supports, results in an increased signal: background ratio on autoradiograms.

Pentavalent antimony (Sb) is the classical treatment for visceral and cutaneous leishmaniasis. We investigated Sb levels in serum, liver, spleen, and skin of hamsters administered therapeutic dosages of Sb (600 and 300 mg Sb/kg). Single administration of Sb was more effective against hepatic parasites than dividing the same total dose into multiple administrations, which suggests that for elimination of hepatic parasites in vivo, peak Sb concentration is more important than total area-under-the-curve levels. Serum Sb declined with an initial half-life of 1 hr. Skin Sb levels (352 µg Sb/g 1 hr after 600 mg Sb/kg) were initially higher than liver levels (77 µg Sb/g) or splenic levels (156 µg Sb/g), but levels were comparable (7–24 µg Sb/g) in the three organs by 8 hr after dosing. The generally comparable levels of Sb in the skin and in the visceral organs support the present clinical practice of administering the same dosage of Sb for cutaneous and visceral leishmaniasis.

High levels of leucine aminopeptidase (LAP) have been detected in Schistosoma mansoni eggs. In this report we demonstrate that this enzyme is immunogenic in mice infected with either S. mansoni or S. japonicum. The anti-schistosomal agent, praziquantel, causes rapid release of this enzyme from schistosome eggs in vitro. Praziquantel treatment of S. japonicum infected mice is associated with a significant decrease in anti-LAP antibodies. Anti-LAP IgM antibody levels decreased more than did anti-LAP IgG antibodies.

Helminth eggs have resisted analysis by electron microscopy because fixatives, dehydrating agents, and embedding media penetrate these eggs poorly. Slam-freezing at liquid nitrogen temperature followed by freeze-substitution and Spurr's medium embedment provides preservation of the internal structure of the Schistosoma mansoni egg shell, developing miracidium, and perimiracidial structures. The egg shell consists of the three previously described layers (outer microspinous, middle intermediately dense, and inner dense layers) with cribriform pores. A newly described layer (Reynolds' layer) develops subjacent the egg shell and is comprised of densely-packed branching filaments. A single layer of squamous cells (von Lichtenberg's envelope) closely adheres to Reynolds' layer. Between von Lichtenberg's envelope and the embryo is a space (Lehman's lacuna); this space is initially filled with electron-lucent fluid, but subsequently masses of granulofloccular material (Cheever bodies) develop; Cheever bodies are partially membrane bound. Epidermal plates differentiate from superficial cells of the embryonal cell mass, while epidermal ridges differentiate from cells just below the surface of the embryonal cell mass. The cytoplasmic layer (von Lichtenberg's envelope) interposed between the host extracellular fluid and the developing miracidia effect a barrier against a simple passive diffusion; this infers that complex macromolecules, such as schistosomal egg antigen, undergo active, and perhaps selective, transport in or out of the egg.

Indirect immunofluorescence of Schistosoma mansoni adult worm sections has revealed that the early immunoglobulin response is directed toward the parasite digestive tract. One of the components of the worm gut is a cysteine proteinase which degrades host hemoglobin ingested by the parasite. In this report the purified proteinase (SMw32) was used in ELISA and immunoblot analyses to study the specific antibody response during the course of an acute infection. We have found high titer IgG antibody in S. mansoni infected, but not uninfected, mice. The anti-proteinase response involves IgM, IgG1, IgG2a, and IgE isotypes. Total IgM and IgG levels increased by week 3 post-infection and remained elevated throughout the study (7 weeks). Increased titers (IgM, IgG) of specific anti-proteinase were also apparent by week 3 post-infection, long before fecal eggs were detectable. Mean anti-proteinase IgG stabilized at high titer by week 5 post-infection, while IgM titers decreased to near background levels. Anti-proteinase IgE was first detectable at week 4 and reached peak titers by weeks 6 and 7. The strong antibody response to the purified SMw32 proteinase is consistent with the early reactivity of S. mansoni infected mice and humans to a 31 kDa component of the worm gut described by others.

Rats were infected orally with 50 or 100 metacercariae of Clonorchis sinensis. Anti-Clonorchis IgE antibody, determined by passive cutaneous anaphylaxis, in the serum of infected rats appeared 30–40 days after infection and persisted for at least 120 days. Total amount of IgE fixed on the mast cells, detected by reverse passive cutaneous anaphylaxis with anti-rat IgE, was significantly more in the infected rats than in uninfected rats. Worm burden at 290 days post-infection did not correlate to anti-Clonorchis IgE antibody titers, reverse passive cutaneous anaphylaxis titers, or anti-Clonorchis anaphylactic antibody on the mast cells, determined by active cutaneous anaphylaxis. Active cutaneous anaphylaxis titers interrelated to reverse passive cutaneous anaphylaxis titers, suggesting a correlation between the amount of anti-Clonorchis anaphylactic antibodies and total IgE on the mast cells. Sensitivity of passive cutaneous anaphylaxis with anti-BSA IgE antibody was significantly suppressed in Clonorchis infected rats. Moreover, anti-BSA IgE titers in the infected rats were inversely related to reverse passive cutaneous anaphylaxis titers, indicating that increase of IgE antibody on the mast cells by Clonorchis infection interfered with sensitization of anti-BSA IgE antibody.

This paper demonstrates that protected water supplies, in the form of boreholes, can reduce the prevalence of dracunculiasis (guinea worm disease) in affected communities from a point prevalence of ≥50% to 0% or near 0% within 3 years of intervention. Studies in Nigeria show that boreholes sited within a village and used exclusively for drinking water are most effective, while less accessible or malfunctioning boreholes have a less dramatic impact on prevalence. In contrast to the situation in villages served with boreholes, the prevalence of guinea worm in the unserved villages remained almost unchanged. The rapid benefits of protected rural water supplies and the decline of dracunculiasis, including the rise in school enrollment and fall in the rate of school absenteeism, are highlighted together with other socioeconomic benefits.

Ivermectin was tested for possible prophylactic action against the third and fourth larval stages (L3 and L4) of Onchocerca volvulus inoculated into chimpanzees. The infective larvae (L3) were obtained from laboratory-raised black flies. Eighteen chimpanzees were inoculated, each with approximately 250 L3. Six were treated with ivermectin (200 µg/kg) on the day of inoculation, 6 were treated with ivermectin on day 28, and 6 were not treated. Monthly skin snips were taken for the next 30 months to detect patent infection. One of the chimpanzees treated with ivermectin on the day of infection developed a patent infection as did 4 of the 6 treated at day 28 and 4 of the 6 control animals. The results suggest that ivermectin may have a partial in vivo effect against the L3 of O. volvulus but has no effect against later larval stages of the parasite.

In examining skin snips from 1,830 Gabonese 32 were found to have microfilariae indistinguishable from Microfilaria rodhaini. The microfilaria is 300.2 µm long and 2.2 µm wide. Specific clinical signs were not identified, as the same person often was infected by other filaria.

The avidin-biotin-peroxidase complex enzyme-linked immunosorbent assay (ABC-ELISA) and standard ELISA were used for the detection of Echinococcus granulosus antibody in sera of 101 patients operated on for hydatid disease, 40 patients with miscellaneous nonhydatid diseases, and 61 normal subjects. Sensitivity and specificity of the two procedures were comparable and the geometric mean antibody titer detected with ABC-ELISA was higher than with standard ELISA. The ABC-ELISA is a sensitive, specific, simple, and convenient method for diagnosing hydatidosis.

Foods obtained in markets in Bangkok were cultured for bacterial enteric pathogens and examined for their similarity to strains isolated from children under 5 years of age in Bangkok in 1986. Salmonella was isolated from 17%, Campylobacter from 12%, and enterotoxigenic Escherichia coli (ETEC) from 3% of 510 foods examined. Campylobacter was isolated from 13.5%, ETEC from 13%, and Salmonella from 12% of 1,230 children under 5 years of age with diarrhea. Eighty-eight percent of children infected with Salmonella were infected with serotypes isolated from foods of animal origin. Six percent of children with Salmonella were infected with the same serotype containing plasmids with identical endonuclease restriction patterns as isolates from food. Eighty-seven percent of children with Campylobacter were infected with the same serotypes and biotypes found in food of animal origin. Thirty-one percent of heat-labile enterotoxin (LT) producing ETEC from foods contained genes coding for LT II, but LT II ETEC was not isolated from children. Twenty-one percent of ETEC isolated from foods vs. 53% isolated from children were resistant to 2 or more antibiotics (P < 0.01). Salmonella and Campylobacter, but not ETEC, isolated from foods were similar to strains isolated from children. Foods of animal origin are an important source of Salmonella and Campylobacter in Thailand.

Three children developed Staphylococcus aureus food poisoning due to enterotoxin type B following ingestion of milk from a goat with overt mastitis.

To determine whether deer may serve as reservoir hosts for the Lyme disease spirochete, we sought evidence of infection in nymphal Ixodes dammini derived from larvae that had engorged on white-tailed deer. A total of 19 deer were shot in two Lyme disease foci in Massachusetts during September 1986, the season in which larvae were most abundant. An average of 342 larval ticks of this species were collected from each deer. Of those that developed to the nymphal stage, the gut contents of 185 were examined for Borrelia burgdorferi by a direct fluorescent antibody test. Spirochetes were detected in about 1% of these nymphs, a rate of infection attributable to transovarial transmission. In contrast, infection was detected in 23% of 39 field-swept nymphal ticks of the same cohort that were collected during the following season. Although deer may be infested by numerous larval I. dammini, such ticks appear not to become infected by Lyme disease spirochetes.

From May 1983 to January 1984, 517 patients with laboratory confirmed dengue were studied at a hospital in Manila. Secondary dengue infections were diagnosed in 78% of these cases. Peak admission (28%) occurred towards the end of the rainy season in November. Most patients (78%) were <15 years old but only 3 were infants. Although some type of hemorrhagic finding occurred in 460 cases (89%), only 110 were classified as dengue hemorrhagic fever and the remainder as dengue fever with hemorrhagic manifestations. The clinical course was usually mild. Gastrointestinal bleeding was present in 65 cases, but only 2 patients developed shock. No fatalities occurred.

Dengue 2 was the predominant serotype with 53 isolates, followed by dengue 1 with 48 isolates, dengue 3 with 39 isolates, and dengue 4 with only 8 isolates. Dengue 2 was the only serotype with more isolates from sera with a homologous HI antibody titer > 1:20 (57%) than from sera with a homologous HI titer ≤1:20 (43%). In contrast, most of the dengue 1 isolates (63%) were from sera with a homologous HI antibody titer <1:10, and this serotype was strongly associated with primary infections.

This study shows that dengue infections remain an important cause of pediatric hospitalization in the Philippines; however, the occurrence of life-threatening dengue hemorrhagic fever as has been described in several other large urban areas of Southeast Asia appears to be rare.

Maguari virus, a member of the Bunyamwera serogroup (family Bunyaviridae, genus Bunyavirus) has not been isolated north of Trinidad. Anecdotal information from other investigators has indicated the presence of antibody to Maguari virus in human residents of south Florida. We attributed such antibody to either cross-reactivity with Tensaw virus, the only Bunyamwera serogroup virus known in south Florida, or to crossreactivity to an antigenic subtype or variant of Tensaw virus. Five strains, identified as Tensaw virus when they were isolated from mosquitoes collected in south Florida more than 20 years ago, were retrieved from storage. They were compared by serum dilutionplaque reduction neutralization tests with Bunyamwera serogroup prototypes Tensaw, Maguari, Cache Valley, and Tlacotalpan viruses. The south Florida isolates were shown to be most closely related to prototype Tensaw virus and most distantly related to prototype Maguari virus. One isolate could not be distinguished from prototype Tensaw virus, and the other 4 appeared to be subtypes of prototype Tensaw virus.

More than 300 serum samples from humans in south Florida were tested for neutralizing antibody to prototypes Tensaw and Maguari viruses and to 3 of the field isolates. Thirteen had antibody to prototype Tensaw virus only, 19 to prototype maguari virus only, and 39 to both. Antibody to all but 6 of these 71 was attributed to infection with Tensaw virus, to a subtype of Tensaw virus, or to travel or birth outside the United States. It is likely that those with antibody to Maguari virus only had been infected with yet another subtype of Tensaw virus, although another, undiscovered, Bunyamwera serogroup virus may exist in south Florida.

As previously observed for dengue viruses, vertical (i.e., transgenerational) transmission of Japanese and St. Louis encephalitis viruses by Aedes albopictus takes place when the fully formed egg, enclosed in the chorion, is oviposited. The demonstration of such a mechanism for three flaviviruses suggests that vertical transmission of all mosquitoborne flaviviruses may occur in the same manner.

The levels of albumin, IgG, IgM, and complement (C3) were determined by enzyme-linked immunosorbent assay in Aedes albopictus and Phlebotomus papatasi at regular intervals after feeding on human blood. Albumin disappeared most rapidly; by 48 hr, detectable levels of albumin had decreased 100-fold. In contract, IgG and IgM survived longer and were still detectable at low levels several days after ingestion. C3 was intermediate in its rate of degradation. In general, serum protein disappearance occurred more rapidly in Ae. albopictus than in Ph. papatasi, despite a larger volume of blood ingested by the former.

Over the past two decades, an impressive body of literature has accumulated on the antineoplastic and antiparasitic activity of inhibitors of polyamine biosynthesis. Perhaps the best known to parasitologists is difluoromethylornithine (DFMO) which is effective clinically against African sleeping sickness. This is a timely, comprehensive, and well-written collection of review articles on polyamines and the pharmacological relevance of inhibitors of polyamine biosynthesis.

The first three chapters of the book focus on inhibitors of the best studied enzymes of polyamine metabolism including ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase, and polyamine oxidase. Chapter 4 reviews evidence for and against various proposed biological functions of polyamines, including their effects on nucleic acid structure, macromolecular synthesis, and membranes. For the molecular biologically inclined, Chapter 5 summarizes recent advances in the molecular cloning of ODC and S-adenosylmethionine decarboxylase, and the role of gene amplification in resistance to ODC inhibitors.

Parasite Life Cycles, by Dickson D. Despommier and John W. Karapelou. xii + 127 pages, illustrated. Springer-Verlag New York, Inc., 175 Fifth Avenue, New York, New York 10010. 1987. $35.00.

Examens de Laboratoire en Medecine Tropicale, by P. Bouree. vii + 151 pages, illustrated. Masson Editeurs, 120, Bd. St.-Germain, 75280 Paris, Cedex 06, France. 1987. paperbound.

The Great Malaria Problem and Its Solution, by Ronald Ross. xxii + 236 pages, illustrated. The Keynes Press, British Medical Journal, BMA House, Tavistock Square, London WC1H 9JR, United Kingdom. 1988. $73.00.

Smallpox and Its Eradication, by F. Fenner, D. A. Henderson, I. Arita, Z. Jezek, and I. D. Ladnyi. xvi + 1,460 pages, illustrated. World Health Organization, 1211 Geneva 27, Switzerland. 1988. $150.00.

Control of Lymphatic Filariasis: A Manual for Health Personnel, by the World Health Organization. 89 pages, illustrated. World Health Organization, 1211 Geneva 27, Switzerland. 1987. $9.00, paperbound.

18 January 1988

To the Editor:

The following letter relates to the article by Neill and others on the ultrastructure of Schistosoma mansoni eggs appearing on pages 142–164 of the current issue. It has been slightly modified by the Editor.

18 January 198

To the Editor:

We have noted the comments of one of the referees and remain unabashed in our use of eponyms in our description of the ultrastructure of the Schistosoma mansoni egg. The terms and those honored are:

Reynolds' layer—Edward S. Reynolds—Creator of the lead citrate strain who taught us to quantitate and carefully interpret electron micrographs; his advice, encouragement and support over 20 years of investigation warrants his part in these discoveries.

von Lichtenberg's cells (and envelope)—Franz von Lichtenberg—Pioneer researcher in schistosomiasis whose ideas, enthusiasm, and encouragement has directly or indirectly nurtured the model concepts of schistosome biology as pertains to granuloma formation, overall pathobiology, and immunology of schistosomal infections.