Plan of action. Information.
Explore the source record for details and available documents.
Communicable Disease Control↗
Biomedical subjects
J W Leduc
Publications and source records attributed to J W Leduc.
Prevalence of sand fly fever, West Nile, Crimean-Congo hemorrhagic fever, and leptospirosis antibodies in Pakistani military personnel.
To determine the prevalence of antibodies to viral diseases known or suspected to be present in Pakistan, we studied 570 sera from three groups of adults; two of the groups were involved in outbreaks of hepatitis, and the third included men admitted to a hospital for evaluation of febrile illnesses. Immunoglobulin G antileptospiral antibody was found in 1 to 6% of the subjects, with the highest rate in enlisted military personnel hospitalized for febrile illness. One man in the group with febrile illness had significantly elevated immunoglobulin M antileptospiral antibody titers. However, in a group of recruits experiencing suspected non-A, non-B hepatitis, 19 (11%) of 173 had a 4-fold rise in immunoglobulin M antibody to leptospirosis. Antibody to sand fly fever viruses was found in 27 to 70%. Antibody to West Nile virus was present in 33 to 41% of subjects. Antibody reactive with Japanese encephalitis virus was present in 25%, but plaque reduction neutralization tests suggested this to be cross-reaction with West Nile virus. All 212 specimens tested for antibody to Crimean-Congo hemorrhagic fever and Hantaan viruses were negative. This study indicates that diseases known to be prevalent in other areas of southwest Asia and the Middle East are also prevalent in northern Pakistan and may impact on those traveling or working in this area.
Adolescent↗
Serum levels of tumor necrosis factor-alpha, interleukin-1, and interleukin-6 in hemorrhagic fever with renal syndrome.
Hemorrhagic fever with renal syndrome is an acute viral disease caused by hantavirus. On the basis of clinical observation, the illness is divided into five sequential stages: febrile, hypotensive, oliguric, diuretic, and convalescent. Because interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) are mediators responsible for fever, septic shock, and acute phase protein induction, we examined, using ELISA, the presence of these three cytokines in 276 sera collected during the Korean Conflict from 110 patients. Detectable levels (> 20 pg/ml) of TNF-alpha, IL-1 beta, and IL-6 occurred in 14, 14, and 33% of these samples, respectively. There was a significant correlation between serum levels of IL-1 beta and TNF-alpha (r = 0.66, p < 0.001), IL-1 beta and IL-6 (r = 0.59, p < 0.001), and IL-6 and TNF-alpha (r = 0.71, p < 0.001). The pathophysiologic processes of HFRS do not have clear or consistent correlations with alterations in the levels of the cytokines studied.
Disease Progression↗
Global surveillance for recognition and response to emerging diseases.
Explore the source record for details and available documents.
Communicable Disease Control↗
Serological relationships among viruses in the Hantavirus genus, family Bunyaviridae.
We examined the serological relationships among 32 hantavirus isolates collected from numerous geographic regions and hosts. We prepared rat immune sera to each virus and used these sera in hemagglutination inhibition (HAI) tests, enzyme-linked immunosorbent assays (ELISA), and plaque-reduction neutralization tests to establish the antigenic relationships among the isolates. Our studies included viruses that had been partially characterized previously, as well as isolates for which little or no serological data were available. Our results indicate that, in addition to the four established serological groups of hantaviruses, represented by Hantaan, Seoul, Puumala, and Prospect Hill viruses, there exist at least two other distinct groups of hantaviruses. These groups are represented by Thailand 749 virus, an isolate from Bandicota in Thailand, and by Thottapalayam virus, an isolate from Suncus in India. To compare more closely the antigenic relationships of the isolates to prototype Hantaan virus, we examined the reactivities of Hantaan G1- or G2-specific monoclonal antibodies with the envelope proteins of a number of the isolates. We found that several epitopes defined by monoclonal antibodies to the G2 protein were highly conserved as detected by HAI tests and ELISA. Almost all of the isolates could be neutralized by at least one G2-specific monoclonal antibody. In contrast, epitopes defined by G1 monoclonal antibodies were conserved only among Hantaan-like viruses.
Animals↗
Phylogenetic analyses of virus isolates in the genus Hantavirus, family Bunyaviridae.
We constructed a phylogenic tree by pairwise comparison of the deduced amino acid sequences encoded in the medium (M) genome segments of 13 hantaviruses. Five distinct branches were identified, four of which are represented by Hantaan, Seoul, Puumala, and Prospect Hill viruses. These groups corresponded to those previously established by serological and genetic means. In addition, we present sequence information for the M segment of Thailand virus and demonstrate that it represents a unique, fifth branch on the dendrogram. We show that a tree nearly identical to that constructed from the deduced amino acids encoded in the M segments of these viruses can be constructed by comparing nucleotide sequences of a 333-bp region of the M segments of the same hantaviruses. This region can be amplified, for most hantaviruses, by reverse transcriptase-polymerase chain reaction (RT-PCR) techniques, using a single primer pair. By using this method, we constructed a consensus tree for 30 hantaviruses, including 15 isolates for which we PCR-amplified and sequenced the 333-bp region. In addition to the five branches described above, we identified a sixth unique hantavirus group represented by Dobrava virus, an Apodemus isolate from Slovenia. Although we were unable to PCR-amplify the M segment of Thottapalayam virus, a distantly related hantavirus isolated from a shrew captured in India, we were able to amplify, clone, and sequence a portion of the small (S) segment of that virus. When we compared our Thottapalayam sequence to corresponding S segment sequences of other hantaviruses, the results indicated that this virus may represent a seventh, distinct group of hantaviruses.
Animals↗
Serum levels of alpha and gamma interferons in hemorrhagic fever with renal syndrome.
Hemorrhagic fever with renal syndrome is an acute viral disease caused by Hantavirus. On the basis of clinical observation, the illness is divided into five sequential stages: febrile, hypotensive, oliguric, diuretic, and convalescent. Because interferons can be induced by viruses, and because their stimulating effects on immune cells can alter the course of viral infections, we examined the presence of alpha interferon (IFN-alpha) and gamma interferon (IFN-gamma) in 276 serum samples collected from 110 patients during the Korean Conflict. We tested these sera for IFN-alpha by bioassay with bovine kidney MDBK cells, and for IFN-gamma by a sandwich ELISA with antibodies specific for human IFN-gamma. We found variable, but persistently elevated levels of IFN-gamma throughout the various phases of the disease, which suggested persistent immune activation through convalescence. Moderate levels of IFN-alpha were found in all stages of infection.
Animals↗
Passive protection of mice against lethal Francisella tularensis (live tularemia vaccine strain) infection by the sera of human recipients of the live tularemia vaccine.
The relative role that humoral immunity plays in protection against infection with the intracellular bacterium, Francisella tularensis, remains controversial. Cellular immunity is thought to play the major and perhaps only role. The authors, in this article, investigate the immunologic and protective properties of immune serum collected from human recipients of the live tularemia vaccine (LVS). Sera of recipients of the vaccine demonstrated reactivity with the vaccine strain by enzyme-linked immunosorbent assay and Western blot analysis. This reactivity appeared to be directed primarily against the lipopolysaccharide of LVS and demonstrated complete cross-reactivity with fully virulent F. tularensis (Schu4). Pooled immune sera protected mice fully against a 10,000 LD50 challenge with the LVS strain relative to non-immune sera. The protection was abrogated by dilution or preadsorption with the LVS strain but not by preadsorption with Escherichia coli, which suggests specificity of protection. The authors conclude that antibodies to the LVS strain of F. tularensis are generated by live vaccination in humans and play a significant role in protection of mice against lethal challenge with the same organism. These antibodies crossreact completely with fully virulent F. tularensis, but whether they play a role in protection against fully virulent human tularemia strains requires further experimentation.
Animals↗
Serologic and virologic evidence of a Prospect Hill-like hantavirus in Wisconsin and Minnesota.
The purposes of this study were to determine if hantaviruses were present in the Great Lakes port areas of Wisconsin and Minnesota and if so, to identify which virus and which rodent host species were involved. Rodents were trapped in Duluth, Minnesota, Superior, Green Bay, and Milwaukee, Wisconsin, all ports of call for international maritime shipping. A total of 675 wild rodents were captured and tested, including 310 meadow voles (Microtus pennsylvanicus), 173 Norway rats (Rattus norvegicus), 179 Peromyscus spp., (including white footed mice [P. leucopus] and deer mice [P. maniculatus gracilis and P. maniculatus bairdii]), and 13 house mice (Mus musculus). Twenty percent of the rats, 17% of the meadow voles, 8% of the house mice, and 3% of the Peromyscus spp. had antibody to a hantavirus by immunofluorescent antibody assay (IFA). By the plaque-reduction neutralization test (PRNT), nine of 36 meadow voles, one of 4 P. leucopus, and one of 34 rats had hantavirus antibody, with the highest titers to Prospect Hill (PH) virus. All of the PRNT-seropositive individuals were from the twin cities of Superior and Duluth. Hantavirus antigen was detected in lung tissue by IFA in M. pennsylvanicus and Peromyscus spp., but not in rats. Two hantaviruses, designated SD-1 and SD-2, were isolated from M. pennsylvanicus captured in Duluth and found to be very similar to prototype PH virus by cross-IFA and cross-PRNT. Virus isolation attempts were unsuccessful from tissues of the Peromyscus spp. and the rats.
Animals↗
Isolation of a strain of a Hantaan virus from a fatal case of hemorrhagic fever with renal syndrome in Slovenia.
Hemorrhagic fever with renal syndrome (HFRS) has been serologically confirmed in Slovenia during the last seven years. There is evidence that three hantaviruses (Hantaan, Puumala, and a newly described form termed Dobrava) circulate simultaneously in this area. Recently, a hantavirus was isolated from the urine and brain tissue of a fatal case of HFRS. Positive immunofluorescent reactions with reference human sera and monoclonal antibodies were first recognized after the second cell culture passage. Extensive cross-reactivity between our isolate and prototype Hantaan virus, strain 76-118, and Hantaan-like isolates from the former Yugoslavia, Fojnica and Plitvice, was revealed by enzyme-linked immunosorbent assay with specific rat antisera. The reaction pattern of the isolate was similar to the prototype Hantaan virus by indirect immunofluorescent assay with a panel of monoclonal antibodies. Furthermore, the specificity of the isolates was confirmed by analysis of polymerase chain reaction products of this virus with five restriction endonucleases. This appears to be the first isolation of a strain of prototype Hantaan virus from a fatal case of HFRS in Europe.
Adult↗
Grouping of hantaviruses by small (S) genome segment polymerase chain reaction and amplification of viral RNA from wild-caught rats.
A single pair of consensus primers in the polymerase chain reaction (PCR) amplified a conserved region of the small genome segment of twenty hantavirus isolates. Isolates tested included representatives of the four recognized hantaviruses, Hantaan, Seoul, Puumala and Prospect Hill, as well as isolates from Mus musculus (Leakey), Bandicota indica (Thailand 749), and Suncus murinus (Thottapalayam). Viruses from the Nairovirus and Phlebovirus genera yielded negative results. The amplification products were 281-nucleotide pairs (np) in length, with the exception of Thottapalayam, which had an amplification product of approximately 320 np. Products of all isolates were detected by Southern hybridization with a 32P-labeled Hantaan 76-118 amplicon, while an oligonucleotide probe to a conserved region of the amplified fragment failed to detect some isolates of Seoul and Puumala viruses. Restriction endonuclease analysis allowed three groupings: Hantaan-like viruses, Seoul-like viruses, and a diverse group of patterns for the other viruses. Differences were found within the Seoul-like virus group by this method, whereas the Hantaan-like viruses were shown to be similar. RNA extracted from tissues of seropositive and seronegative rats trapped in Baltimore showed the practical application of the test. Hantavirus-specific RNA was detected in 12 (92%) of 13 seropositive rats, but not in seronegative rats. This simple method for detecting and characterizing hantaviruses has potential for epidemiologic studies and for diagnosing human hantavirus infections.
Animals↗
Lymphocytic choriomeningitis virus infection and house mouse (Mus musculus) distribution in urban Baltimore.
Four hundred eighty house mice (Mus musculus) were trapped primarily from urban sites in Baltimore, Maryland from 1984 to 1989 and tested for antibody to lymphocytic choriomeningitis virus (LCMV). The majority of mice (95%) were trapped in residences at two city locations (n = 260), or in an urban park (n = 196); five additional sites were sampled. Overall, 9.0% of the mice were LCMV antibody positive and infected animals were obtained from six of eight sites, including all three of the primary city sites, where the prevalence varied significantly (3.9-13.4%). The location with the highest prevalence was an inner city residential site where positive mice were found significantly clustered within blocks and households. In this location, LCMV antibody prevalence was also significantly correlated with estimates of mouse density within individual blocks. The focal nature of LCMV infection in house mice may result from contact or vertical transmission of virus in conjunction with the highly structured social system of mice, which promotes inbreeding and limited dispersal.
Animals↗
Venezuelan equine encephalomyelitis virus infection in and transmission by the tick Amblyomma cajennense (Arachnida: Ixodidae).
To assess a possible role of ticks as the maintenance host for epizootic strains of Venezuelan equine encephalomyelitis (VEE) virus, laboratory experiments were conducted to determine if ticks could become infected, maintain, and transmit the virus. Larval and nymphal Amblyomma cajennense (F.) and larval Dermacentor nitens Neumann ticks were exposed to epizootic VEE virus (Trinidad donkey strain) by allowing them to feed on viremic guinea pigs (strain 13). In A. cajennense, transstadial transmission was observed from larvae to nymphs and adults. Horizontal viral transmission to a mammalian host was accomplished by nymphs. Infection rates in nymphs and adults were 2% (42/2,750) and 4% (9/244), respectively, afer ingestion of virus as larvae. Virus was detected in A. cajennense adult ticks for up to 171 d after infection in the larval stage. A cajennense, exposed as nymphs, ingested virus but did not become infected (0/164 after 10 d after taking an infective bloodmeal). No virus was detected in D. nitens 7 d after exposure. These findings suggest that A. cajennense potentially could be involved in an interepizootic maintenance cycle of epizootic VEE viral strains.
Animals↗
Human-rodent contact and infection with lymphocytic choriomeningitis and Seoul viruses in an inner-city population.
We collected 1180 sera and 1363 questionnaires with information on demography, rodent exposure, and history of travel from persons visiting a sexually transmitted disease (STD) clinic in Baltimore between 1986-1988. Serological tests for two rodent-borne viruses detected antibodies to lymphocytic choriomeningitis virus (LCMV) in 54 individuals (4.7%; n = 1149) and antibodies to Seoul virus (SEOV) in three persons (0.25%; n = 1180). Antibody prevalence to LCMV increased with age, but there were no racial or sexual differences. Neutralization tests and questionnaire responses implicated a domestic, rat-borne hantavirus as the source of SEOV antibody. Self-reported human-rodent contact indicated more exposure to house mice than rats within residences, although rats were more commonly sighted on streets. Infections with rodent-borne viruses were rare compared to the high rates of reported contact.
Adult↗
Evidence of human infection with a rat-associated Hantavirus in Baltimore, Maryland.
Human sera obtained from two sources in Baltimore were tested for antibodies against a Hantavirus by a variety of techniques. Four persons out of 1,788 had hantaviral antibody as demonstrated by immunofluorescent assay, enzyme-linked immunosorbent assay, and neutralizing assay. Neutralizing antibody titrations against three test viruses indicated that infections were caused by a rat-associated virus. Medical histories of two subjects indicated life-long residence in Baltimore and an absence of foreign travel, implicating a local source of infection.
Adolescent↗
Geographical distribution and age related prevalence of antibody to Hantaan-like virus in rat populations of Baltimore, Maryland, USA.
Recent studies indicate that domestic rats (Rattus norvegicus) from harbor-side areas within port cities of the United States are infected with a Hantaan-like virus. The geographical distribution of seropositive rats may be extremely localized within these urban environments. We surveyed four widely separated residential sites distant from the harbor within Baltimore, Maryland, USA, to determine the geographical distribution and prevalence of antibody to Hantaan-like virus in rats from urban areas of high human population density. Captured rats were weighed and examined for sexual maturity to allow some estimation of age, and their sera were examined by indirect immunofluorescent antibody assay for antibody to Hantaan virus. Seropositive rats were found at all four sites within Baltimore. Increasing antibody prevalence and high titers were associated with increasing rat weight and sexual maturity. Our results show that infection of rats by a Hantaan-like virus is widespread in Baltimore. Antibody in rats may be due to infections acquired during maturation or the delayed seroconversion of rats infected prior to weaning.
Age Factors↗
Transovarial transmission of yellow fever virus by a sylvatic vector, Haemagogus equinus.
Explore the source record for details and available documents.
Animals↗
[Anti-Hantavirus antibodies in school children in Salvador, Bahia].
Hantavirosis are emerging diseases in the Americas. Although considered rare in children, among the five cases diagnosed in Brazil, one was in this age group. To know the serum-prevalence of hantavirosis in the pediatric group (schoolchildren) of low social economic level in Salvador, Bahia State, and to associate demographic, socio-economic and environmental factors to the serologic results, a standard questionnaire was applied and blood samples were collected from 379 students of two public schools. Sera were tested by indirect Immunofluorescent Antibody (IFA) IgG for Hantaan Virus (HTN) and Immunoenzymatic test (ELISA) for Sin Nombre viruses. Ages varied from five to seventeen years with a mean age of 10.2 years. The proportion of sera positive to HTN virus was 13.2%, and there were no positive antibodies to SN virus. The frequency of positivity was higher in the older group, similar among sexes and racial groups, and there was no association with the exposure to urban rodents. The antibodies anti-HTN serum-prevalence in low social economic level school children is high and confirm the circulation of hantaviruses in Salvador-Bahia, Brazil; the nonobservation of antibodies anti-SN indicates that the species are other than Sin Nombre Virus.
Adolescent↗