The American Journal of Tropical Medicine and Hygiene - Volume 45, Issue 6, December 1991

This issue completes Volume 45 and closes out the first year of editorial activity in the Atlanta office of the Journal. The study of health and disease in the tropics is dynamic and increasingly complex. Clinical studies, field epidemiology investigations, application of control technologies, basic biology of disease agents and vectors, immunology, molecular biology, drug studies and what is most exciting, reports of multiple combinations of these subject areas, have all appeared in recent pages of the Journal. This variety is clearly illustrated in the current issue that we like to think of as an end of the year present with something for everyone.

The impact of human retrovirus infections in Africa remains an issue of fundamental importance, and the opening paper gives evidence of a lower than expected incidence of some of these agents in Somalia.

The following list of Journal reviewers is as of November 16th, 1991. Each one of the manuscripts published during 1991 was seen by two or more of those listed below. These references also have seen manuscripts that are still under review or have been rejected. The number and geographic diversity represented by the reviewers listed is indicative of the rich resources strengthening and sustaining the Journal.

Abraham, David, Philadelphia, PA; Addiss, David, Atlanta, GA; Ades, Edwin W, Atlanta, GA; Ager, AL, Miami, FL; Aikawa, Masamichi, Cleveland, OH; Ajello, Libero, Atlanta, GA; Altstatt, Leslie B, Silver Spring, MD; Andrade, Zilton A, Bethesda, MD; Anthony, Ronald L, APO San Francisco, CA; Arata, Andrew, Arlington, VA; Araujo, Fausto G, Palo Alto, CA; Ariet, Jordi C, New York, NY; Arnot, David E, New York, NY; Ash, Lawrence R, Los Angeles, CA; Atkinson, Carter T, Cleveland, OH; Ayadle, Jaime, Potomac, MD; Azad, Abdu F, Baltimore, MD; Baer, George, Atlanta, GA;

A seroepidemiologic survey was conducted to determine the prevalence of human immunodeficiency virus type 1 (HIV-1), HIV-2, human T cell lymphotropic virus type I (HTLV-I), and Treponema pallidum infection among southern Somalis. Sera were collected from 1, 269 study subjects in the urban area of the capital city, Mogadishu, and in the rural towns of Merka, Qoryoley, and Kismayo. The subjects included 57 prostitutes, 79 sexually transmitted disease (STD) patients, and 1, 133 others, including outpatient and hospitalized patients with leprosy, tuberculosis, other infectious diseases, individuals from rehabilitation camps and secondary schools, and Ethiopian immigrants. Results indicated that none of the sera were positive for HIV-1 and HIV-2 by Western blot, but one was positive for HTLV-I. The prostitutes had a significantly higher prevalence of treponemal antibody (50.8%, P < 0.0001) than either the STD patients (12.6%) or the other subjects (5.2%). Epidemiologic data indicated that 94% of the males and females were circumcised and only 2.6% of the males used condoms. Overall, the results of this study suggested a very low prevalence of HIV-1, HIV-2, and HTLV-I infections, especially among prostitutes and STD patients, who were considered at greatest risk of contracting these retroviral infections.

Different virus isolates causing hemorrhagic fever with renal syndrome (HFRS) were compared using a neutralization test. Patient convalescent sera and antisera prepared in rabbits were used to compare Puumala-related Hantavirus isolates from Finland, Sweden, Belgium, and the USSR. The majority of European isolates were indistinguishable from each other using both homologous rabbit antisera and patient convalescent sera. The European isolates of HFRS were also compared with prototype Hantaan (the etiologic agent of Korean hemorrhagic fever). The one-way cross-reaction between the Hantaan and Puumala viruses, previously described using human convalescent sera tested by indirect immunofluorescence and immunoprecipitation, was also seen by the neutralization test.

A family selection scheme, based on the progeny from individual females, was used to select several families of the insect vector Culicoides variipennis that were resistant or susceptible to oral infection with bluetongue virus. Genetic crosses between families showed results consistent with control by a single genetic locus (blu). Reciprocal crosses suggested a maternal effect in which the genotype of the mother determined the phenotype of the offspring. The dominant and recessive natures of the resistant (blu r) and susceptible (blu s) alleles were determined by the sex of the parent. The results provide the first evidence to suggest a genetic locus controlling insect vector competence for infection with an arbovirus.

An immunoblot for the detection of leptospirosis was developed in our laboratory. Antigen prepared from Leptospira interrogans serovar bataviae was dotted onto nitrocellulose paper and blocked with skim milk. Test and control sera diluted 1:20 were applied to the dot, incubated, and washed. Anti-human IgM colloidal gold conjugate was added and the dots were washed. A positive reaction was shown by the development of a pink dot against a white background. The test was performed on 62 sera that tested positive for leptospirosis by a microagglutination (MA) test, on 40 sera that were positive by an indirect hemagglutination (IHA) test, and on sera from forty healthy blood donors. Four sera from the blood donors showed a faint pink dot, but the remainder showed a colorless reaction. All 62 sera that tested positive by MA were positive by this new test, while 95% of the 20 sera that tested positive by IHA were positive. Tests for IgG antibody were performed on 20 sera positive by MA using protein A-colloidal gold conjugate, and all showed weak reactivity. The results confirmed previous findings that most antibodies present in leptospirosis patients are of the IgM type. The ELISA takes three hours to perform, but the gold immunoblot can be completed in 30 min. In addition, the test blot can be kept as a permanent record, and is a significant improvement over existing tests.

Serum specimens obtained from culture-positive group A meningococcal meningitis patients in Cairo, Egypt were tested for immunoglobulin M (IgM) antibodies to Neisseria meningitidis group A polysaccharide by direct and IgM capture enzyme-linked immunosorbent assays (ELISAs). Sera from patients with meningitis caused by other bacteria were used as negative control specimens. The IgM antibodies to this antigen were detected by direct ELISA in 93% of 58 specimens obtained from patients with group A meningococcal disease three or more days after hospital admission, and by IgM capture ELISA in 83% of 60 such specimens. Sixteen percent of 25 specimens obtained three or more days after admission from negative control patients were positive by direct ELISA, and 4% were positive by IgM capture ELISA. The correlation coefficient of the results with the two assays was 0.85.

In a randomized clinical trial, norfloxacin was compared with nalidixic acid in the treatment of acute invasive diarrhea, with particular reference to shigellosis in adults. Of 104 patients studied, 40 were positive for Shigella in stool cultures, of which 22 received norfloxacin and 18 received nalidixic acid. The patients in these two groups were comparable on admission. In the treatment of culture-positive shigellosis cases, the responses to therapy with both drugs were similar, except that the duration of fever, anorexia, and abdominal pain were less in those who received norfloxacin. Norfloxacin appeared to be superior to nalidixic acid in the treatment of shigellosis cases caused by Shigella strains resistant to nalidixic acid.

The objective of this project was to construct specific and sensitive molecular probes and amplification primers for Cryptosporidium parvum that could be used in diagnosis, retrospective tissue studies, and in epidemiologic surveys. Whole genomic DNA was extracted from oocysts of C. parvum purified from human and bovine feces. A genomic library was constructed in plasmid pUC18 and propagated in Escherichia coli DH5 α. Transformants were screened by colony hybridization and autoradiography. The 2.3-kilobase segment in plasmid pHC1, a clone specific for C. parvum, was sequenced by the Sanger method. Computer analysis gave a G + C content of 35%. A 400-base region (bases 470–870) was selected as an amplification target because it contained a unique restriction endonuclease site that could serve as a useful marker. Primers of 26 nucleotides each were synthesized. Sensitive and specific amplification of the target sequence was demonstrated both by ethidium bromide staining of agarose and acrylamide gels, and by hybridization with chemiluminescence-labeled synthetic oligonucleotide probes.

A recombinant Plasmodium vivax circumsporozoite (CS) antigen representing approximately 70% of the CS protein was expressed in yeast and adsorbed onto aluminum hydroxide for use as a malaria vaccine. In a study of safety and immunogenicity, 30 volunteers were divided into four groups of 5, 5, 10, and 10 individuals, and inoculated intramuscularly with 50, 100, 200, or 400 µg of vaccine, respectively. Primary vaccinations were followed by two booster immunizations at six weeks and six months. Overall, the vaccine was well tolerated. Following the third vaccination, one volunteer developed acute hepatitis of uncertain etiology that resolved without sequelae. All volunteers in the 400-µg group, and six of 10 in the 200-µg group generated IgG against P. vivax CS protein, as determined by Western blot using recombinant CS protein. However, the magnitude of the antibody response measured by indirect immunofluorescence of intact sporozoites or enzyme-linked immunosorbent assay against the recombinant protein was low, and responses could not be boosted. Antigen-driven replication studies using peripheral blood lymphocytes failed to detect proliferative responses specific to peptide sequences represented in the recombinant vaccine, except in one volunteer. Minimal humoral and cell-mediated immune responses developed in most recipients who received this recombinant CS vaccine.

The pharmacokinetics and effectiveness of three dosage regimens of quinine were studied in a group of 59 children with severe malaria. The children were randomized to receive high-dose intravenous or intramuscular quinine (20 mg salt/kg loading, then 10 mg salt/kg every 12 hr), or low-dose intravenous quinine (10 mg salt/kg loading, then 5 mg salt/kg every 12 hr). In the group receiving the high-dose intravenous regimen, mean high and low quinine concentrations were consistently greater than 10 and 6.5 mg/l, respectively. Peak concentrations as well as the time required to achieve them were similar in the intramuscular and high-dose intravenous groups. The low-dose intravenous quinine regimen resulted in mean peak concentrations > 6 mg/l and mean low concentrations > 3.5 mg/l. All blood concentrations exceeded the 99% in vitro inhibitory concentration (EC99) of 0.89 mg/l or less of quinine for 60 isolates of Plasmodium falciparum, which were taken from children with malaria during the same period. Judged by a number of clinical criteria, the response was better in patients receiving the high-dose than the low-dose intravenous regimen. The time taken to clear parasites with both the high-dose intravenous and intramuscular regimens were significantly shorter than those obtained in the low-dose group. We have also shown for the first time that the rate of parasite clearance can be directly related to the area under the quinine concentration versus time curve. This applied to all three quinine regimens (r = 0.4252, P < 0.02; n ≤ 35). Five patients, two on the low-dose regimen, two on the intramuscular regimen, and one on the high-dose regimen, developed hypoglycemia after admission, but in these cases, insulin concentrations were correspondingly low. No significant quinine toxicity was observed in any of the cases. The high-dose intravenous quinine regimen described here may be optimal for treatment of severe falciparum malaria in areas of chloroquine resistance in Africa. Our data provide no justification for reducing the dose of quinine in the treatment of severe malaria in Africa. The intramuscular regimen could provide a satisfactory alternative in areas where intravenous administration might be delayed or is impossible.

We report the biological and biochemical parameters of Leishmania parasites (MNEO/US/90/WR972) isolated from a rodent host, Neotoma micropus, collected in Texas. Footpad inoculations of WR972 promastigotes into BALB/c mice and Syrian hamsters resulted in ulcerating lesions six and eight weeks post-inoculation, respectively. Using monoclonal antibody-stained touch preparations, amastigotes were found in the liver of both laboratory hosts. Infection of J774 macrophages with WR972 promastigotes supported the growth of amastigotes for 12 days at 35°C. The WR972 parasite was identified by enzyme electrophoresis as L. mexicana. Isozyme comparison of WR972 with 42 L. mexicana isolates (from humans and rodents) from four different endemic areas, including Texas, suggest that these parasite populations are identical for approximately 97% of their genetic loci. Pulse field gel electrophoresis (PFGE) of WR972 resolved 18 chromosomes with a size range of 300–>2,000 kb. The karyotype strongly resembles that of two other Texas L. mexicana isolates from humans. Taken together, the PFGE, hybridization, and isoenzyme data suggest that the wood rat isolate (WR972) is identical to parasites from human cutaneous lesions isolated in Texas and Central America. In addition, the biological characteristics of WR972, its infectivity of BALB/c mice and the Syrian hamster, and the potential of the isolate to infect, transform, and divide in J774 macrophages indicate that WR972 will be pathogenic in humans if transmission occurs. Health care providers should consider this possibility when studying the epidemiology and control of cutaneous leishmaniasis in Texas.

A 37-year-old hemophiliac patient with known, asymptomatic human immunodeficiency virus infection and chronic Chagas' disease was admitted to the hospital complaining of fever and headache. A computed tomographic scan revealed multiple ring-enhancing lesions in both cerebral hemispheres. No antibodies to Trypanosoma cruzi were found in the cerebrospinal fluid. Treatment for toxoplasmosis of the central nervous system, which was considered the most likely diagnosis, was instituted, but the patient died after progressive neurologic deterioration. An autopsy revealed severe meningoencephalitis caused by T. cruzi.

Two groups of Wuchereria bancrofti-infected Haitians who had undergone treatment with diethylcarbamazine (DEC) were followed for up to five years after treatment to document the long-term effects of treatment on adult worms and microfilariae and on the recurrence of infection. One group of 69 persons who had received 12 daily treatments had a significant decrease in microfilaria levels until year 4, when a small number of individuals experienced a resurgence of this parasite stage in the peripheral blood. In a second group of 57 persons who had been treated weekly for 12 consecutive weeks, there was a greater reduction in the microfilaria levels following treatment, and for the full four years of followup, these levels remained more depressed than those of the group that received daily treatment. Our results indicate that DEC kills or permanently sterilizes adult W. bancrofti. Furthermore, these results demonstrate conclusively that in Haiti, the use of DEC provides long-term benefits to treated persons, even though they continue to reside in an area with endemic filariasis.

Alveolar echinococcosis is a serious and often fatal disease of humans that in most cases can be efficiently cured only by complete surgical resection of the Echinococcus multilocularis lesion. In a few patients, however, a spontaneous cure of the disease has been observed by demonstrating the presence of lesions with dead metacestodes. The present study shows a comparative analysis of the cellular (lymphoproliferative assay) and humoral (antibody activity in an Em2 enzyme-linked immunosorbent assay [ELISA] and immunoblotting) immune response in 1) patients who were cured by a radical surgical resection of the E. multilocularis parasite lesion, 2) patients who had a partial surgical resection of the parasite lesion, 3) patients who had a non-resectable alveolar echinococosis, and 4) patients who were shown to be spontaneously cured and had lesions with dead parasites. The in vitro lymphoproliferative response to E. multilocularis antigen stimulation was very high in cured patients who had radical surgery or in patients with lesions containing dead parasites, but it was significantly lower in patients who had partial surgical or no resection. Antibody concentrations in the Em2-ELISA were high in patients who had incomplete or no surgery, and low or negative in cured patients who had radical surgery or in patients with lesions containing dead parasites. Immunoblot analysis of patient sera revealed a consistent antibody banding pattern among cured patients with radical surgery and patients with incomplete or no surgery, whereas cured patients with lesions containing dead parasites showed a very faint antibody pattern. The distinct differences in the parasite-specific humoral and cellular immune status between self-cured patients and other patient groups with different courses of alveolar echinococcosis may provide insight into potentially protective immune mechanisms.

One hundred forty-four of 166 adults with acute viral hepatitis (AVH) admitted to an Egyptian fever hospital were followed for 12 months. The hepatitis B surface antigen (HBsAg) carrier rate in 95 with hepatitis B virus (HBV) hepatitis decreased from 53% at three months to 13% at 12 months. At 12 months, 22% of the male patients had persistent HBsAg compared with only 7% of the female patients. The HBsAg carrier rate was 25% at 12 months in those with schistosomiasis compared with 9% in those with only acute HBV infection. Splenomegaly persisted in those with palpable spleens at the initial examination and others developed splenomegaly. The prevalence of splenomegaly increased from 11% on admission to 20% at 12 months in those with only AVH, and from 40% to 69% in those with concomitant schistosomiasis. Patients with concomitant schistosomiasis had higher mean values for liver function test results and a greater proportion had abnormal liver function test results during hospitalization and followup than those with AVH only. Concomitant schistosomiasis increased the prevalence and prolonged splenomegaly and morbidity due to AVH. Both male sex and concomitant schistosomiasis prolonged the HBsAg carrier state. We propose that AVH frequently converts uncomplicated intestinal schistosomiasis to hepatosplenic schistosomiasis.

Serum kinetics of bothropic venom were evaluated in eight snakebite patients, who due to a national shortage, received no specific antivenom therapy. The cases were clinically classified as mild, moderate, and severe. Patients were bled sequentially and serum levels of venom were assayed by ELISA. Venom level ranges differed among the groups, with peak levels of less than 13 ng/ml, 32 ng/ml, and 12O ng/ml for the mild, moderate, and severe groups, respectively. There was no clear pattern of kinetics in the groups. Regression analysis involving the variables severity and peak venom levels yielded a statistically significant correlation (rs = 0.80, P < 0.05). These data indicate that different amounts of circulating venom correlate with clinical severity, even in highly complex venoms, and stress the importance of careful clinical classification in the proper management of bothropic incidents.

This book is divided into two parts, General Virology and Specific Virus Families. Part I begins with a brief introduction by the senior editors and proceeds logically, thoughtfully and precisely through taxonomy, structure, viral membranes, replication, genetics (principles and molecular aspects), defective genomes, evolution, pathogenesis, persistence, virus-host-cell interactions, cell transformation by viruses, and interferons, to immunization against viruses. Part II covers specific virus families (Picornaviridae, Togaviridae and Flaviviridae, Coronaviridae, Rhabdoviridae, Paramyxoviridae, Orthomyxoviridae, Bunyaviridae, Arenaviridae, Reoviridae, Retroviridae, Papovaviridae, Adenoviridae, Parvoviridae, Herpesviridae, Poxviridae, Hepadnaviridae, and unclassified agents). The book contains a clear and easy-to-use subject index. The authors of the various chapters are among the most authoritative in their fields and the information is up-to-date. Since the last edition, the editors have added chapters on evolution, latency and persistence, virus-cell interactions, cell transformation, replication of retroviruses, human immunodeficiency viruses, cytomegalovirus, Epstein-Barr virus, papilloma viruses, and agents causing spongiform encephalopathies.