The American Journal of Tropical Medicine and Hygiene - Volume 35, Issue 6, 1986

This list terminated as of 30 June 1986, when the November issue of the Journal was completed. Each of the 195 articles in Volume 35 has been seen by two or more of the colleagues listed below. These referees also have seen manuscripts that are still under review or have been rejected.

It is a pleasure to recognize two new members of the Editorial Board: Diane W. Taylor and Joel M. Dalrymple. Current members of the Editorial Board are A. S. Benenson, Allen W. Cheever, Charles H. Calisher, Joel M. Dalrymple, Carter L. Diggs, James L. Hardy, Rodney C. Jung, Llewelyn J. Legters, Edgar J. Martin, Thomas P. Monath, Harry Most, Franklin A. Neva, S. Michael Phillips (sabbatical leave), Robin D. Powell, Alexis Shelokov, Robert E. Shope, Diane W. Taylor, Harold Trapido, Thomas H. Weller, and Thomas M. Yuill. Despite heavy teaching and research programs, field trips, and illnesses each of these individuals has seen and served as referee on an average of 8 manuscripts.

This report encompasses the results of two studies on the relapse patterns of infections with the B strain of Plasmodium cynomolgi treated repetitively with chloroquine. One study of sizeable dimensions dealt primarily with relapses that occurred within 120 days of onset of patency in infections induced with inocula of 105 to 7 × 106 sporozoites. The second study, of more limited dimensions, dealt with relapses that occurred over a 689-day period after inoculation with 5 × 100 to 5 × 106 sporozoites. Both studies showed that with few exceptions relapses occurred at relatively regularly spaced intervals. The second study showed that frequency of relapse was related directly to the size of the sporozoite inoculum and inversely to the age of the infection; also that an inoculum larger than the minimum infective dose was required for relapse. Attempted correlation of these observations with the new and generally accepted hypnozoite concept of relapse uncovered two areas of serious incompatibility and numerous defects in the experimental base of this conceptualization. With limited provisos, the relapse patterns of infections with P. cynomolgi are fully compatible with the older cyclical development concept. The results of this study argue for caution in discarding this concept and for continuation of efforts to determine the genesis of the extended post-primary attack latent period that characterizes infections with the majority of strains of P. vivax.

Leishmaniasis was diagnosed by demonstrating amastigotes of Leishmania from dermal lesions on the ear of a male long-haired domestic cat from Uvalde, Texas. Leishmania from the cat were propagated in Syrian hamsters, bovine macrophages, and in NNN medium. The organism, in the L. mexicana complex, is apparently the same as that reported from recent human cases in the same area.

The relationship of the progression and regression of cutaneous lesions of 6 owl monkeys (Aotus trivirgatus) to the responses of their peripheral blood leukocytes (PBL) in vitro to mitogens and to leishmanial antigens, as well as their delayed skin test responses (DTH) in vivo to leishmanin antigen, were studied after primary and challenge infections with Leishmania braziliensis panamensis (WR 128 or WR 539). All 6 infected monkeys developed primary and satellite cutaneous leishmanial lesions which were measured for up to 30 weeks in 3 of the monkeys and up to 52 weeks in the other 3 monkeys. Two owl monkeys which had recovered from cutaneous leishmaniasis demonstrated acquired resistance when challenged with an intradermal inoculation of L. b. panamensis (WR 128).

Reactivity of PBL from infected owl monkeys to PHA, Con A, and PWM was similar during primary and challenge infections to that observed prior to infection. Reactivity to leishmanial antigens was detected at 20 to 28 weeks post-infection (PI), became statistically significant after 28 weeks and remained elevated up to 52 weeks PI and after challenge infections. During primary infections DTH responses to leishmanin antigen were detected as early as 8 weeks PI, and continued up to 27 weeks PI. After challenge infections DTH reactivity was positive at 25 and 37 weeks, the only times the response was evaluated. The immunological responses of owl monkeys to L. b. panamensis were similar in many respects to those observed in humans with localized cutaneous leishmaniasis. This nonhuman primate model should be useful for future studies involving the immunology and chemotherapy of cutaneous leishmaniasis.

Methylbenzethonium chloride (MBCl) decreased the growth of Leishmania major promastigotes and amastigotes in vitro. This decrease occurred during 4 days of exposure to the drug at concentrations of 0.1 to 2.5 µg ml-1. MBCl at 2 µg ml-1 killed almost 100% of the free living promastigotes and 87% of amastigotes within 4 days of treatment. Electron microscopy studies showed marked swelling of mitochondria in treated parasites. A possible additional effect on the parasite surface membrane is discussed.

C57BL/6 mice were immunized against Leishmania donovani infection with a subcutaneous vaccination protocol. Groups received 3 injections at 4-day intervals combining glucan and killed promastigotes harvested from either logarithmic or stationary phase cultures. Controls were immunized with glucan alone, stationary or log phase promastigotes alone, or were untreated. All groups were challenged intravenously with stationary phase promastigotes at day 45 post-immunization. Results revealed that animals immunized with the glucan-killed parasite vaccine, utilizing promastigotes derived from either log (GPL) or stationary phase cultures (GPs), demonstrated significant resistance against infection as compared to controls or untreated mice. Additionally, the reduction in hepatic amastigote proliferation in mice immunized with GPs was significantly greater than in mice immunized with GPL.

Forty isolates of Leishmania, representing all major species infecting humans and one parasite of lizards, were examined for their ability to secrete an extracellular acid phosphatase activity. This enzyme, which was originally described and characterized from a Sudanese strain of L. donovani, was detected in the culture supernatants of all species of promastigotes examined except for L. major and L. tarentolae. There were quantitative differences among species in their levels of enzyme activity and in the sensitivity of the exoenzyme to inhibition by L(+) tartrate. Upon electrophoresis in nondenaturing polyacrylamide gels, extracellular acid phosphatase from L. braziliensis panamensis, L. tropica, and L. mexicana showed distinctive patterns which were similar for all isolates of a given species, while enzymes from L. donovani isolates differed from one another in relative electrophoretic mobility. Enzymes from all species appeared heterogeneous, showing either discrete multiple bands or single diffuse bands on gels stained for enzyme activity. Although the biological function of the extracellular acid phosphatase is presently unknown, the exoenzyme may be of value as a diagnostic or taxonomic characteristic.

A simple, quantitative method has been developed to assess the viability of Giardia lamblia trophozoites after exposure to a potentially lethal agent. This method utilizes the ability of trophozoites which remain viable to replicate and multiply. In this study, the percent dead trophozoites after incubation in 20% fresh human serum was determined first by morphologic criteria and then by the ability of parasites to multiply in fresh medium over 48 hr. Using the number of parasites after 48 hr of growth, the original number of dead trophozoites in the serum-exposed samples was determined by extrapolation from a standard growth curve. Ten sera which killed from 7% to 89% of trophozoites by morphologic criteria, killed 8% to 92% using the culture method; these two assays for viability correlated highly (r = 0.96). Use of the culture assay allows the assessment of the lethal effects of serum and can be applied both to the study of other host defense mechanisms on Giardia trophozoites and to antimicrobial susceptibility testing.

A vertical polyacrylamide gradient gel (3% to 7%) was designed to facilitate the electrophoretic resolution and classification of isoenzyme patterns of Entamoeba histolytica isolates. The following enzyme systems were used: phosphoglucomutase (PGM), hexokinase (HX), glucosephosphate isomerase (GPI), and malate dehydrogenase (ME). The modifications in the electrophoretic procedure and sample preparation allowed the reproducible comparison of enzyme patterns of axenic, monoxenic, and mixed cultures of E. histolytica isolated from humans. The clear distinction obtained in gradient polyacrylamide gels, between amebic isoenzyme bands and those from bacteria, renders this technique adequate for application to epidemiological studies where mixed cultures are used. The isoenzyme patterns of eight isolates from asymptomatic carriers, rigorously characterized by the absence of clinical, endoscopic, and serological findings were studied and compared with three well characterized pathogenic strains, cultured under axenic conditions. Our observations confirm the existence of distinct isoenzyme patterns for PGM, HX, and GPI in pathogenic and nonpathogenic strains, and reveal the consistent presence of more than one band for GPI. In addition, a previously undescribed band for GPI with an Rf of 0.64 in a carrier strain was found. The results suggest that while carriers usually harbor amebas with nonpathogenic isoenzyme patterns, pathogenic patterns also may be found in carriers.

In order to study the prevalence, incidence, and symptoms of infections with Giardia lamblia and Entamoeba histolytica, we followed 251 expatriates in Bangladesh over a 1-year period. Microscopic examination of fecal specimens was performed upon enrollment, at 3-month intervals, and during episodes of diarrhea. Specimens were cultured for bacteria and samples of serum and saliva were collected for antibody studies (IgG and SIgA).

The prevalence of G. lamblia infections was 5.2% and the incidence 11.8%. Children aged ≤10 years and newcomers were most frequently infected (P < 0.02). Symptoms were present in 37% of the subjects infected with G. lamblia. A systemic antibody response was observed in 57% of symptomatic patients and 35% of asymptomatic subjects during the first 2 months of infection.

The prevalence and the incidence of E. histolytica infection were 3.2% and 8.6%, respectively. Infections with E. histolytica were correlated with the duration of stay in Bangladesh; <1 year 7% vs. >3 years 26% (P < 0.01). Most expatriates infected with E. histolytica were asymptomatic (90%). Three adult patients, who were resident in Bangladesh for <1 year, were symptomatic but none of them developed dysentery or a serological response. Four of 25 asymptomatic subjects had significant antibody titers. Three of these people were seropositive for ameba at the beginning of the study.

The local immune response, reflected by specific secretory IgA in saliva samples, correlated poorly with both E. histolytica and G. lamblia infections.

Over 100 years ago, David Livingstone reported the presence of tsetse flies in the Okavango swamps in northern Botswana. They have persisted in the region and recently have been responsible for many cases of Rhodesian sleeping sickness caused by Trypanosoma rhodesiense in visitors to the area. The clinical manifestations in illustrative cases of this disease are described. One patient who refused treatment died five months after being infected. One patient died of encephalopathy complicating treatment with Melarsoprol (Mel B) and one died in a hemorrhagic state associated with a heavy parasitemia early in his illness. Most patients treated early respond well to treatment with specific drugs, usually Suramin, and are cured. In those with involvement of the central nervous system the treatment required is more hazardous, but usually is effective in curing the patient.

The symposium provided dramatic evidence of the value of the use of polyamine inhibition via α-difluoromethylornithine (DFMO, eflornithine) for advances in chemotherapy of Trypanosoma brucei gambiense sleeping sickness and Pneumocystis carinii pneumonia in acquired immune deficiency syndrome (AIDS) and also for further understanding the metabolic importance of the ubiquitous polyamines in these organisms.

In a 6-month period, 25 appendices with histological involvement by schistosomiasis were radiographed. Eleven showed varying degrees of radiographically detectable calcification having a spotty, linear, or amorphous pattern affecting either a short segment or the whole appendix. Four of these appendices had a mixed pattern and one also had nodular calcification in the mesoappendix. In only 1 patient was the appendiceal calcification visible on preoperative abdominal radiographs. In 5 asymptomatic patients, not submitted to surgery, appendiceal calcification was detected during radiologic evaluation of urinary schistosomiasis.

The comparative prevalences of urinary tract lesions in 2 villages where urinary schistosomiasis was endemic and in a control village free from infection were assessed by ultrasonography. Of the 822 residents >4 years of age in the first village (Sébéri) where the prevalence of infection was 57%, 279 were examined by ultrasonography. The prevalence of bladder lesions was 71% in those 5–14 years of age, 57% among adult men, and 24% among women in this endemic village, compared to 10%, 16%, and 6%, respectively, in the control village.

Renal lesions were infrequent among adults and there was no significant difference in the rates between Sébéri and the control village. Among children, moderate hydronephrosis was absent in the control village, but was observed in 19% of the boys 5–14 years of age and 2% of the girls 5–14 years of age in Sébéri.

Sixty schoolchildren of the second endemic village with urinary egg counts ≥100 eggs/10 ml of urine were examined by ultrasonography.

The overall prevalence and the severity of bladder lesions in the 2 endemic villages were significantly related to the urinary egg count.

Normal and passively immunized Fischer rats were infected with 75Se-selenomethionine-labeled cercariae of Schistosoma mansoni. Migration of the parasites from skin to lungs to liver was monitored by autoradiographic analyses of these sites. Labeled parasites migrated from skin to lungs with high efficiency in normal and immune rats; disappearance of labeled parasites from the lungs was slower in immune rats. Labeled parasites accumulated in the liver, reaching maximal values by 11 days post-infection in both groups and remaining constant through day 21. Half the number of labeled parasites were detected in the liver of immune rats. The total number of labeled parasites detected in the skin, lungs, and liver was constant through day 5, then declined to about 60% of this value by day 11 in both groups. Over the next 10 days, the rate of decline decreased significantly in normal rats but did not change in immune rats. By day 21 post-infection, nearly 50% fewer labeled parasites were detectable in immune rats. We conclude that a subpopulation of parasites in the lungs is the target of protective antibody in the serum used for passive immunization. Target parasites, retained longer in the lungs, were probably prevented from migrating successfully to the liver. Another parasite subpopulation migrated to the liver with normal kinetics.

Lung schistosomula isolated from normal and passively immunized rats were transferred by intravenous injection into recipient rats and their continued migration from lungs to liver compared. No differences in portal perfusion worm yields were detected in normal recipients; equally reduced yields were detected in passively immunized recipients. We conclude that the effects of antibodies during week 1 post-infection were insignificant or reversible.

Liver fibrosis in schistosomiasis is associated with prominent accumulations of fibroblasts. Primary cell cultures were prepared from the fibrotic livers of Schistosoma mansoni-infected mice, and cells with the appearance of fibroblasts by light microscopy were isolated from these cultures. Proliferation of these cells was examined in coculture experiments with syngeneic inflammatory cells. T cell-enriched mononuclear cells from spleens of S. mansoni-infected or normal mice, and Kupffer cell/macrophages from fibrotic liver all stimulated the proliferation of liver fibroblasts, as measured by 3H-thymidine uptake. Primary cultures of mouse skin fibroblasts showed similar responses to coculture, but an established fibroblast line, 3T3, was unresponsive. Cell-free supernatant medium from coculture experiments did not affect fibroblast proliferation, perhaps because of the requirement for serum in the culture medium. Liver fibroblasts derived from this disease model may be especially suitable for study of the interaction between tissue inflammation and fibrosis.

Eosinophil chemotactic activity in sera from mice undergoing an acute stage of schistosomiasis japonica and mansoni was examined. Eosinophilotactic activity in the serum was dependent on the dose and time of infection. Eosinophilotactic activity in sera from S. japonicum-infected mice was higher than that from S. mansoni-infected mice when they were compared at the comparable dose and time of infection. After gel chromatography on Sephadex G-200, eosinophilotactic activity in sera from mice infected with 30 cercariae of S. japonicum for 5 weeks was detected in the high molecular weight component. On the other hand, when sera from mice infected with 30 cercariae of S. japonicum for 8 weeks was chromatographed through Sephadex G-200 columns, eosinophilotactic activity was segregated into high (>455,000) and low (<13,000) molecular weight components. High molecular weight ECF in sera from mice infected with 30 cercariae of S. japonicum for 8 weeks had high affinity to Con A, and was stable to heating or pronase digestion, but was sensitive to periodate oxidation, indicating its polysaccharide or glycoprotein nature. This high molecular weight ECF could be adsorbed by, and eluted from immunoaffinity beads coated with rabbit IgG anti-S. japonicum adult worm antibody. Thus, at least some part of circulating high molecular weight ECF would be derived from adult parasites.

The ability of serum samples obtained from humans with schistosomiasis mansoni to recognize Schistosoma mansoni soluble egg antigens (SmSEA) was assessed by the enzyme-linked immunotransfer blot (EITB) method. The sera from 15 infected patients before and 2 years after treatment with oxamniquine (n = 30) recognized bands ranging in molecular weight from 9 to 200 Kd. A 31 Kd component of SmSEA was recognized by all infection sera, but not by normal human serum. The sera from 2 humans infected with S. haematobium and 2 with S. japonicum also recognized the 31 Kd band present in SmSEA, whereas those from 2 humans infected with Fasciola hepatica did not. The 31 Kd antigen was isolated by electrophoresing SmSEA through a 15% SDS-acrylamide gel, followed by excision and electroelution of the 31 Kd band. The purified 31 Kd was used in conjunction with ELISA at a concentration of 1 µg/ml to confirm the apparent genus specificity of this protein. Thus, the sera of patients infected with S. mansoni, S. haematobium, or S. japonicum were clearly reactive in ELISA, whereas normal human serum or sera from patients with F. hepatica were negative. In conclusion, the 31 Kd protein appears to be a good candidate for developing a screening assay for the immunodiagnosis of schistosomiasis.

Nine people living in Rhode Island, New York, Pennsylvania, Florida, or California acquired autochthonous brugian filariasis. Each patient had an enlarged lymph node containing a single worm or, in one patient, a pair of worms. Most worms were in lymphatic vessels within the node, but two worms were in the substance of the node. Ten worms were studied, seven female and three male. Female worms contained paired uteri that occupied most of the body cavity of the worm, and male worms contained a single reproductive tract. No worms were gravid. The diameter of the worms was small, 30 µm to 75 µm. The usual diameter of female worms was 65 µm to 75 µm, and 45 µm to 50 µm for male worms. The morphologic features of these worms, their anatomical location, and their geographic distribution are all characteristic of infection with a North American Brugia species.

In the present study a partially purified antigen preparation enriched in Fasciola-specific antigens (designated p3 and 4) was used in the enzyme-linked immunoelectrotransfer blot (EITB) to identify polypeptides which induce antibody formation in acute fascioliasis. The pattern of antigens recognized by the sera of infected rabbits, humans, and cows was also compared. Similar but not identical patterns of recognition were obtained for the different models tested; the main antigenic polypeptides recognized were in clusters within 27–38, 18–23, and 11–14 Kd molecular weight (Mr) ranges. An antigen of 31–33 Kd was one of the most prominently recognized by all of the acute infection sera tested. This antigen, as well as those in the 18–23 Kd range, appear to have good specificity, as they are not recognized by antibodies to S. mansoni or P. westermani adult worm extracts. To further characterize and evaluate these low Mr antigens, we have isolated polypeptides by electrophoresing p3 and 4 F. hepatica antigens in 10%–15% gradient gels, identifying the desired Mr range with prestained markers, cutting individual gel strips, and then isolating them by electroelution. Antigen fractions of 19–23 and 31–33 Kd were isolated in this manner, re-electrophoresed, transferred to nitrocellulose and found to be reactive with the sera from a rabbit with acute fascioliasis. At least one of these antigens, of 20 Kd Mr, has been obtained by this means with a high degree of purity. This, as well as other antigen fractions isolated, showed high absorbance values in ELISA when reacted with the serum from a rabbit with an 8-week-old F. hepatica infection. Thus, acute F. hepatica infection induces a complex antibody response where the most immunogenic antigens are low Mr components. We have identified these, isolated potential immunodiagnostic antigens, and applied them successfully to a convenient serodiagnostic assay (ELISA).