The American Journal of Tropical Medicine and Hygiene - Volume 50, Issue 3, March 1994

The main pathologic findings in 23 patients with acquired immunodeficiency syndrome (AIDS) and Chagas' disease are reviewed; five are from our own experience and 18 from the literature. The presence of Trypanosoma cruzi parasites and/or T. cruzi antibodies in blood and cerebrospinal fluid was recorded and computerized tomograms of the brain were evaluated. Twenty (87%) of the 23 subjects developed severe, multifocal or diffuse meningoencephalitis with necrosis and hemorrhage associated with numerous tissue parasites. The second most severely affected site was the heart. Seven (30.4%) of the 23 cases had myocarditis on pathologic examination. It was acute in four patients, chronic in two, and simultaneously acute and chronic in one. Acute myocarditis and meningoencephalitis are interpreted as being caused by relapses of chronic T. cruzi infections. An AIDS permissive role is suggested for these conditions since immunologic defense against T. cruzi is mediated mainly by T lymphocytes, whose CD4 subpopulation is depleted in patients with this disease. Consequently, AIDS is a factor that may favor the reactivation of T. cruzi infections. The lesions reported in the association of Chagas' disease with AIDS were compared with those reported from patients without AIDS having fatal, acute, vector-transmitted infections, contaminated blood transfusions, or accidental exposures in the laboratory. For the latter three, meningoencephalitis is uncommon. Only immunosuppressed cases of Chagas' disease have been described as having a pseudotumoral presentation that shows expanding lesions with a mass effect in the cranial cavity that causes intracranial hypertension and simulates neoplasms (tumors such as gliomas, lymphomas, metastases, etc.).

Mice, C57Bl/6N (B6) and BALB/cAnN (BALB), infected with Schistosoma mansoni were examined 8–26 weeks postinfection (PI) to estimate the fecundity of the worms and the contribution of death of worms and the death of heavily infected mice to the decrease in worm numbers in chronic infections. Portal worms were recovered by perfusion and the lungs were examined for parasites shunted from the portal circulation. Animals that died were more heavily infected than those that survived. Between eight and 12 weeks PI, this loss of worms resulted in a net decrease of approximately 19% of worm pairs in surviving BALB mice, but of only 4% in B6 mice. Loss of portal worms to the lungs after the eighth week of infection was 9–13% of portal worms in BALB mice and 3–4% in B6 mice. The estimated rates of egg production by S. mansoni decreased slightly with time in both strains of mice. At 12 and 20 weeks PI, tissue eggs per worm pair and eggs passed in the feces per worm pair often decreased as the intensity of infection increased. We do not consider the loss of worms in the murine host relevant to most infections in humans because of the high intensity of infection relative to body size in mice and the high frequency of severe portal obstruction in murine infections.

Individual male and female schistosomes approximately three weeks of age were implanted into the portal venous system of C57Bl/6 mice to produce infections with a single pair of Schistosoma mansoni or S. japonicum. Mice were killed between seven and 54 weeks after infection. Worm fecundity was measured by counting eggs accumulating in the tissues and eggs passed in the feces. Schistosoma mansoni worm pairs laid approximately 350 eggs per day with no change in the apparent rate of egg laying between eight and 52 weeks after infection and approximately one-third of the eggs were passed in the feces. Schistosoma japonicum worm pairs laid approximately 2,200 eggs per day initially and this decreased to 1,000 eggs per day by the end of the experiment, with one-third to one-half of the eggs being passed in the feces. There was marked variability in the fecundity of individual worm pairs, but the number of eggs passed in the feces of individual mice correlated well with the number of eggs in the intestines at all time points in S. mansoni-infected mice and at the seventh and tenth week of S. japonicum infection.

More than 250 strains of Leishmania isolated from different localities and hosts in the New World were analyzed by enzyme electrophoresis, and their electromorphic profiles were compared with 19 reference strains representing most of the described species of this parasite. The 18 enzymic loci analyzed were very polymorphic, and the strains were classified into 44 zymodemes, each grouping strains with the same enzyme profiles. Each zymodeme was considered as an elementary taxon and the phenetic and phylogenetic relationships were determined by agglomerative hierarchical, ordination, and cladistic techniques. The different classification methods produced very similar results. The 44 zymodemes could be clustered into two groups, corresponding to the subgenera Leishmania and Viannia, by the numerical methods. The subgenus Viannia was shown to be monophyletic and could be further divided into species complexes representing L. braziliensis, L. naiffi, and L. guyanensis/L. panamensis/L. shawi, as well as some isolated taxa including L. lainsoni. The subgenus Leishmania, on the other hand, was polyphyletic, with New World isolates related to L. major clustered separately from the L. mexicana species complex. Most of the other zymodemes in this group represented independent taxa. The results confirm Viannia as a valid taxon but suggest that the status of the subgenus Leishmania should be further investigated. Leishmania braziliensis and L. naiffi were shown to be the most polymorphic species, while L. guyanensis, in spite of being the most common species found in this study, was remarkably homogeneous. The only variants were found south of the Amazon river. North of this river, the species was monomorphic.

Two cloned DNA sequences, λC10 and λG12, have been isolated from a female Anopheles gambiae sensu stricto genomic DNA library in λEMBL4. The λC10 clone hybridized with equal intensity to all five of the six species in the An. gambiae Giles complex tested and was therefore suitable for use as a complex-specific clone. The λG12 clone was selected for its ability to distinguish the two major vectors of malaria within the complex, An. gambiae s.s. and An. arabiensis. Use of libraries consisting of only female DNA prevented the isolation of male-specific sequences. Southern blot analysis of the cloned DNA permitted the development of smaller Alu I subclones suitable for sequencing that still retained the original specificities and sensitivities of λC10 and λG12. Each clone was found to possess a series of repeated sequences in direct tandem array of 92–94 and 68 bases, respectively. A comparison of a number of copies of each of the repetitive sequences within the Alu I subclones enabled the definition of consensus sequences for the repetitive elements in λC10 and λG12. Based on these consensus sequences, two oligonucleotides of 21 and 23 bases designated pAngsl and pAngss were derived from λC10 and λG12, respectively. When tested as probes against DNA dot-blots and squash-blots of mosquito specimens, each oligonucleotide retained the same species specificity as the original clones from which they were derived. The nonradioactive, alkaline phosphatase-labeled pAngsl was able to detect as little as 1 ng of target genomic DNA by chemiluminescent detection in a 5-hr autoradiographic exposure. The pAngss probe could detect 5–10 ng of genomic DNA in similar assays. The new probes exhibit great potential for use in An. gambiae complex species identification because they provide both a means of distinguishing the two major vectors of malaria within the complex and of assessing the quality of squashed mosquito samples by providing a means of standardizing hybridization results.

The gene coding for the envelope (E) glycoprotein of dengue-2 virus was cloned into baculovirus (Autographa californica nuclear polyhedrosis virus). The recombinant virus contained the entire E protein gene, preceded by 38 nucleotides from the end of the prematrix glycoprotein gene and followed by the first 83 nucleotides of nonstructural protein 1. When expressed in Spodoptera frugiperda (Sf9) cells, approximately 1 mg of recombinant E antigen was made per 109 cells. This antigen reacted with polyclonal, antidengue type-2 antibody and a dengue type-2-specific, neutralizing monoclonal antibody. BALB/c mice immunized with the recombinant antigen produced only non-neutralizing antibody against dengue-2 virus, but were partially protected against morbidity and mortality after intracranial challenge with virulent dengue-2 virus.

The present study investigated the serum antibody response to parasite antigens involved in human Plasmodium vivax malaria. Analysis was performed by protein immunoblotting of a pool of P. vivax preparations obtained from blood of patients from Tapachula, Chiapas (southeastern Mexico), and sera from local malarious patients. Patients sera recognized 19 P. vivax antigens with molecular sizes between 17 and 170 kD. The most frequently recognized antigens were proteins of 19, 31, 43, 72, 93, and 97 kD. These proteins could be useful in diagnostic methods and possibly relevant in vaccine design.

To determine the effectiveness of single oral dosages of ivermectin ranging between 20 and 200 µg/kg and to make detailed observations of both the kinetics of parasite killing and the adverse reactions induced by treatment, the present double-blind study on ivermectin treatment of lymphatic filariasis caused by Wuchereria bancrofti was undertaken with 43 microfilaremic patients in Recife, Brazil. Follow-up at one year indicated equivalent efficacy for the 20-, 100-, and 200-µg/kg drug dosages in reducing microfilaremia to geometric means of 13–25% of pretreatment levels. Adverse clinical reactions (predominantly fever, headache, weakness, and myalgia) occurred to some degree in almost all patients but generally lasted only 24–48 hr and were easily managed symptomatically. Adverse reactions were significantly milder in those receiving the lowest (20 µg/kg) ivermectin dose, and they were significantly correlated with individuals' pretreatment microfilaremia levels in all groups. Posttreatment eosinophilia was a regular feature of the response to treatment, with the magnitude and kinetics also proportional to pretreatment microfilarial levels. Transient pulmonary function abnormalities (16 of 42, 38%), liver enzyme elevations (10 of 43, 23%), and hematuria (9 of 42, 22%) developed post-treatment, but all cleared without significant complications. The results indicate that W. bancrofti from Brazil is similar to strains of the parasites studied elsewhere in susceptibility to ivermectin, that the drug's systemic adverse reactions are essentially those resulting from parasite clearance, and that the intensity of these reactions can be significantly reduced by using the low (20 µg/kg) dose of ivermectin. This detailed dose-finding study provides information necessary for developing optimal regimens to treat bancroftian filariasis with ivermectin either alone or in combination with other medications.

We report the case of a 28-year-old male who had been ill with headache and motor weakness for a month and developed sudden pain and blindness of the right eye. During ophthalmoscopy, a worm was recognized penetrating the iris, occupying the anterior chamber for a brief period, returning back behind the iris, and leaving corneal edema with hyphyema. Enucleation was performed to prevent the worm's escape from the eye. The enucleated eye revealed areas of a focal degeneration of sclera and intraocular hemorrhage. Microscopic findings of an abrupt tissue defect and few inflammatory reactions in the uvea suggested very recent migration of a moving worm. The flatworm detected in the anterior chamber was identified to be a juvenile Fasciola sp. This case is presumed to be the first case of intraocular fascioliasis reported in the literature.

Field-collected adult male Ixodes scapularis from Westchester County, New York were bisected and Borrelia burgdorferi infection rates were ascertained by both a direct fluorescent antibody test and an outer surface protein A (OspA) antigen-capture enzyme-linked immunosorbent assay (ELISA). Both assays gave identical antigen positivity rates with 89% concordance between the two assays. Storing dried ticks before ELISA analysis had no significant effect on the ability of the ELISA to determine the presence of OspA compared with assaying live ticks. The OspA antigen positivity rate for dried ticks was 49% compared with 53% for live ticks, with mean OspA antigen spirochete equivalents of 3,388 and 2,823 for dried and live ticks, respectively.

To evaluate the prevalence of spotted fever group rickettsiae along the Adriatic Coast of Croatia, 832 ticks were examined by hemolymph test, direct immunofluorescence, antigen-capture enzyme immunoassay, and polymerase chain reaction. Very good agreement was observed among direct immunofluorescence, polymerase chain reaction, and antigen-capture enzyme immunoassay. Twelve ticks that were positive by hemolymph test and negative by both direct immunofluorescence and polymerase chain reaction presumably do not represent spotted fever group rickettsiae. By direct immunofluorescence, spotted fever group rickettsiae were present in 12% of Rhipicephalus bursa, 10.6% of Rh. sanguineus, and 7.8% of Dermacentor marginatus. From the 98 ticks containing rickettsialike organisms by hemolymph test, seven spotted fever group rickettsial isolates were established in cell culture. Four isolates were identified as Rickettsia conorii. The antigencapture enzyme immunoassay, which utilizes a monoclonal antibody to antigens of the 135-kD surface protein shared among many members of the spotted fever group, is recommended for primary screening of tick samples because it is reliable and yet less labor-intensive than the hemolymph and direct immunofluorescence tests. Although the polymerase chain reaction is too expensive for use as a screening method, it is recommended for confirmation of positive screening results. In addition to the technologic advance of the antigen-capture enzyme immunoassay, this study documented by contemporary methods that R. conorii is present along the eastern Adriatic Coast not only in the classic vector, Rh. sanguineus, but also in Rh. bursa and D. marginatus.

Adult ticks were collected in a rural area of central Greece in order to isolate and identify rickettsiae. A hemolymph test using Gimenez staining was used for detection, while simultaneous isolation was performed using the shell-vial technique. Serologic, antigenic, and genomic characterization of the isolates was achieved by microimmunofluorescence, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP), and pulsed-field gel electrophoresis (PFGE), respectively. Although none of the 242 collected ticks was positive by the hemolymph test, one rickettsial isolate, designated GS, was obtained by the shell-vial technique. This isolate originated from a female Rhipicephalus sanguineus. Microimmunofluorescence serologic typing by the method of Philip and others demonstrated that GS belongs to the same serotype as the recently isolated Rickettsia massiliae (Mtul). Protein analysis by SDS-PAGE and immunoblotting by Western blot revealed similar profiles between the two rickettsiae. Using Alu I, Rsa I, and Pst I restriction endonucleases in PCR-RFLP analysis, GS and R. massiliae were found to possess identical restriction sites. However, PFGE showed differences when the two genomes were digested with Bss HII and Sma I restriction endonucleases, in spite of their equal size. In conclusion, the first rickettsial isolation in Greece was found to be antigenically identical and genotypically close to the French isolate R. massiliae, despite small differences showed by PFGE.

Spotted fever rickettsiosis have been identified on the African continent since their historical description in 1909. However, only Rickettsia conorii and R. africae have been described in Africa, and the current techniques for the detection of rickettsiae in ticks are difficult to apply in large field studies. We report here a preliminary study using genomic amplification by the polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) analysis directly on 310 crushed ticks (Rhipicephalus, Amblyomma, and Haemaphysalis species) collected in 1985 in the Central African Republic. Among 310 specimen tested, 21.6% were positive. The rate of infection ranged from 0% to 64.3%, depending on the tick species. Based on PCR-RFLP, five different rickettsiae profiles were found: R. conorii and R. africae, previously known in Africa, R. rhipicephali, which has never been described in Africa, and two isolates identical to R. massiliae and Mtu5, previously obtained from Rh. turanicus in southern France. This work shows that PCR-RFLP is a powerful tool to study tick collections, and that it is applicable to samples from developing countries. Further work is needed to confirm the identification of the rickettsiae found in this work, using traditional identification procedures.

The activity of lymphocytic choriomeningitis virus (LCMV) in the endemic area of Argentine hemorrhagic fever has been previously reported and represents the first evidence of the coexistence of two arenaviruses pathogenic for humans, Junin and LCMV, in the same geographic area. Data are presented on the prevalence of LCMV human infection in a 10,000-km2 area located in Santa Fe Province, Argentina. Study subjects were males, 15–65 years old, living and/or working in the rural area of 41 localities. One serum sample was obtained from each of 7,227 volunteers from a total population of 21,340 individuals with the described features. Antibodies to LCMV were assessed by means of an indirect immunofluorescence assay. These antibodies were found in 172 serum samples, with titers ranging from 1:8 to 1:128 (geometric mean titer = 15.03), and a mean percentage of infection of 2.38%. A significantly different distribution of positive individuals was found between the eastern (1.54%) and western (3.07%) borders of the region studied (P < 0.0003). The higher percentage of infection on the western side was due to the existence of two clusters of counties with a mean percentage of 6.06% that was significantly different from the 1.67% obtained in the rest of the study area (P < 0.0003). These results provide new information on the LCMV activity in Argentina, and update the evidence on the coexistence of two arenaviruses in the same region of Argentina. This circumstance increases the probability of generation of viral reassortants with changes that could determine the need for new therapeutic and/or preventive strategies for arenaviral diseases.

From July 10 through August 4, 1980, five cases of St. Louis encephalitis (SLE) occurred in and near Fort Walton Beach on the Gulf Coast of northwest Florida. These were the first cases of SLE ever reported from the Florida panhandle. To determine the extent of SLE infection in the community, sera (n = 968) were collected from patients at the local hospital and county public health unit and tested for SLE virus antibody. The SLE attack rate was highest in a centrally located impoverished census tract. There was a trend toward decreasing seroprevalence with distance from the central area of the city. Overall, seroprevalence was higher in males (prevalence ratio = 2.7) and in all areas, seroprevalence increased with age. The serosurvey results suggest that SLE has been endemic in the Fort Walton Beach area.

This hefty atlas, in both English and Italian, is composed of 10 chapters and over 500 photographs, both color and black and white plates. A mixture of outstanding light and electron micrographs illustrates the etiologic agent in diverse morphologic aspects by both direct microscopic observation and in histologic specimens. There are eight chapters, dealing with intestinal ameba and blastocystis, free-living ameba, intestinal and urogenital flagellates and ciliates, blood and tissue flagellates, Plasmodium and Babesia, coccidia, microsporidia, and Pneumocystis carinii. A ninth and tenth chapter detail basic diagnostic criteria and basic techniques for diagnosis, respectively.

Each chapter is divided into subsections dealing with a specific organism or closely related group of organisms. Chapters open with a world map illustrating the geographical distribution and a taxonomic summary of the agent(s). This is followed by a brief discussion of the epidemiology, life cycle, clinical/pathological features, and organ involvement.