Search PubMed⌕ Search

Biomedical subjects

D M Watts

Publications and source records attributed to D M Watts.

At least 73 records · Page 4Linked to original sources
PubMed1991

Demonstration of yellow fever and dengue antigens in formalin-fixed paraffin-embedded human liver by immunohistochemical analysis.

Two immunohistochemical techniques to determine the presence of yellow fever and dengue antigens in fixed tissue samples were developed for the purpose of making retrospective diagnoses of these viral diseases in humans. A horseradish peroxidase label was used for one technique and an alkaline phosphatase label for the other. In the former technique, acid hematin was removed from the tissues, iron-containing pigments were counterstained with Prussian blue, and the product of the diaminobenzidine reaction was enhanced with a dilute solution of osmium tetroxide that differentiated antigen from lipofuscin. In the latter technique, alkaline phosphatase was used as the enzyme labeling system with a red chromogen that contrasted nicely with the pigments in the tissues, as mentioned above. Thus, pigment removal or differentiation from antigen was not required. Replicate sections were cut and mouse polyclonal antibodies for yellow fever and all dengue types were applied to individual sections. On samples positive for dengue antigen, monoclonal antibodies were applied to additional replicate sections to demonstrate antigen of dengue types 1 and 4. In order to test the assay, samples of formalin-fixed liver tissue from Brazilian and Peruvian individuals who had died from a variety of causes as long as eight years earlier were received in a blinded fashion for immunohistochemical analysis. The techniques appeared to be highly reliable for yellow fever diagnosis; however, not enough cases were observed to adequately evaluate the procedures for dengue diagnosis. Both procedures appeared to have similar sensitivity.

Adolescent↗
PubMed1991

Low prevalence of human immunodeficiency virus-1 (HIV-1), HIV-2, and human T cell lymphotropic virus-1 infection in Somalia.

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 less than 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.

Adolescent↗
PubMed1991

Assessment of serological assays for the diagnosis of HIV-1 infections.

Many serologic techniques are available for the detection of HIV-1 infection, but their diagnostic performances have been reported to vary depending on the testing situations. We evaluated eight different serologic assays for detecting HIV-1 antibody in sera from suspected high risk groups in North and East Africa. These included: one ELISA bead assay, three indirect ELISAs, two competitive ELISA assays, one gelatin agglutination assay and a recombinant dot-blot assay. A panel of 38 HIV-1 antibody confirmed positive human sera and a panel of 60 HIV negative sera were tested. All sera yielding discordant results were retested for verification of reactivity. Among the different assays evaluated for detecting HIV-1 antibody, sensitivities ranged from 0.919 to 0.974 and test efficiencies ranged from 94.2-98.9%. All assays failed to detect at least one western blot confirmed positive serum; three tests (Organon, DuPont recombinant and Serodia) produced only one false-negative result. Five of the eight assays did not produce any false-positive results. The Organon viral lysate and the DuPont recombinant ELISAs exhibited the best overall performance (test efficiency = 98.9%).

Africa, Eastern↗
PubMed1990

Replication of Crimean-Congo hemorrhagic fever virus in four species of ixodid ticks (Acari) infected experimentally.

The vector potentials of Hyalomma dromedarii Koch, H. impeltatum Schulze & Schlottke, H. truncatum Koch, and Rhipicephalus appendiculatus Neumann for Crimean-Congo hemorrhagic fever (CCHF) virus (IbAr 10200) were evaluated by intracoelomic inoculation. All three Hyalomma species became infected; infection rates ranged between 80 and 100% at 7-14 d after inoculation, and viral titers increased in unfed specimens almost 100 times above inoculation levels within the first week following infection. Only 40% of the R. appendiculatus became infected, and viral titers of unfed specimens increased less than 10 times above inoculation levels. The virus persisted to 153 d in unfed H. impeltatum. Viral titers were significantly higher in female than in male H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus after blood feeding. Blood feeding had little effect on the viral titers of male Hyalomma species. However, the percentage of female and male ticks from which virus was recovered was significantly higher from fed ticks compared with unfed ticks. No virological evidence of transovarial transmission was found in greater than 78,000 first-generation progeny (larvae, nymphs, and adults) of inoculated female H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus. All species transmitted CCHF virus to guinea pigs when allowed to feed at both 6 and 21 d after inoculation.

Animals↗
PubMed1990

Serological evidence of Crimean-Congo haemorrhagic fever viral infection among camels imported into Egypt.

A serosurvey was conducted during 1986-87 to determine evidence of prior Crimean-Congo haemorrhagic fever (CCHF) viral infection among camels imported into Egypt from Sudan and Kenya. Sera obtained from camesl arriving at the Aswan quarantine station, southern Egypt, were tested for CCHF antibody by the agar gel diffusion (AGD) and the indirect fluorescent antibody (IFA) techniques. CCHF viral antibody was demonstrated in 14% (600/4301) of the camels, with both techniques yielding similar results. CCHF viral antibody prevalence among camels imported from Sudan was lower (12%) than among camels imported from Kenya (26%). Ganjam and Qalyub viral antibody was not detected among the 600 CCHF viral antibody positive sera, but 7% (44/600) were positive for Dugbe viral antibody. CCHF viral antibody was not demonstrated in 400 sheep and 200 cows of native animals. These data indicate that camels imported from Sudan and Kenya had previous CCHF viral infection, but evidence of transmission to animals of Egypt was not obtained. Further studies are needed to assess the possible role of imported animals in the ecology and epidemiology of CCHF virus in Egypt.

Animals↗
PubMed1990

Evaluation of a synthetic peptide-based assay and a rapid dot-blot recombinant test for detection of antibodies to HIV-1 and HIV-2.

Our objective was to evaluate two new serologic assays for detecting HIV-1 and HIV-2 positive and negative sera. A total of 154 human sera from African countries were tested using a synthetic peptide-based passive hemagglutination assay (PHA) and a rapid dot-blot recombinant test (Test-Pack), both of which are marketed as HIV-1/HIV-2 combination assays. Results indicated that the PHA identified all HIV-1 and HIV-2 positive sera, although some were only weakly reactive. It produced one false positive reaction. The Test-Pack correctly detected all positive and negative sera, although several negative sera produced extremely weak reactions. Both tests detected two HIV-2 positive sera which were non-reactive by HIV-1 screening assays.

Evaluation Studies as Topic↗
PubMed1990

HIV infection in Egypt: a two and a half year surveillance.

From April 1986 to mid-October 1988, 19,767 blood samples from individuals of 27 Governorates in Egypt were screened for antibodies to HIV-1. Risk groups included: drug addicts, prostitutes, patients with sexually transmitted diseases or fever of unknown origin, blood or blood product recipients, patients with mental disorders, and contacts of HIV-infected persons. Sera from routine blood donors and foreigners were also tested. All samples which reacted repeatedly by commercial ELISAs were assessed by Western blot (DuPont) for confirmation. Results indicated that 139 (0.70%) of the sera produced repeatedly reactive results by ELISA. Sixty-nine of these were confirmed by Western blot as HIV seropositive. This constituted 0.35% of the total population tested. Only 26 (0.15%) of the Egyptians tested were positive and a total of seven sero-positive individuals were classified as having clinical AIDS. All Egyptian blood donors were negative. Data generated during this 2.5-year HIV serosurvey indicate that the prevalence of confirmed HIV infection in Egypt was exceptionally low, and suggest that HIV is not endemic in Egypt, since all 26 sero-positive Egyptians were linked to HIV exposure abroad.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Serological evidence of dengue fever among refugees, Hargeysa, Somalia.

Epidemics of a malaria-like illness affected several thousand residents of the Dam Camp, a refugee camp near Hargeysa in Somalia, during 1985, 1986, and 1987. The disease was characterized by fever, chills, sweats, headache, back and joint pains for as long as 10 days in some patients. Blood smears from acutely ill patients were negative for malaria. Of 28 acute and 10 convalescent sera tested by the indirect fluorescent antibody (IFA) and by the hemagglutination inhibition (HI) tests, all were negative for antibody to Rift Valley fever, Crimean-Congo hemorrhagic fever, Sindbis, Chikungunya, yellow fever, and Zika viruses. However, antibody reactive to dengue 2 virus was detected by the IFA test in 39% (15/38), and 11 of 29 (38%) of the same sera were antibody positive by the HI test. Also, IgG antibody reactive to dengue 2 was demonstrated in 60% (17/28) of the same sera by the enzyme immunoassay (EIA), and 14% (4/28) were positive for IgM antibody. Of ten patients for which acute and convalescent sera were available, two developed four fold or greater rises in antibody titer evidencing infection. These data suggested that dengue virus may have been the cause of the epidemic among the Dam Camp refugees.

Antibodies, Viral↗
PubMed1989

Time for HIV-1/HIV-2 combination tests?

We should like to report the case of an individual in the Middle East infected with HIV-2 whose serum was negative by our routine ELISA tests for HIV-1. We propose that screening for HIV-2, in addition to HIV-1, be performed on individuals who are clinically determined to be at risk for HIV infection. Commercially available HIV-1/HIV-2 combination tests may serve to identify both infectious agents.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Giant benign mesothelioma.

Pleural mesothelioma is a rare neoplasm that is usually highly malignant, but benign mesotheliomas do occur; approximately 400 cases are described in the literature. We report the case of a young woman with a massive benign mesothelioma that filled the entire left hemithorax but was successfully resected with full reexpansion of the lung.

Adult↗
PubMed1989

Effects of triturated Culiseta melanura (Diptera: Culicidae) on recovery of eastern equine encephalomyelitis virus.

Experiments were done to determine the effect, if any, of larval and adult Culiseta melanura (Coquillett) suspensions on the recovery of eastern equine encephalomyelitis (EEE) virus in baby hamster kidney (BHK) and Vero cell cultures. Although triturated pools of this mosquito reduced the titer of EEE virus added to suspensions, suspensions prepared from as many as 100 Cs. melanura larvae or adults did not reduce titers of virus to undetectable levels. Similarly, the titer of EEE virus in orally infected female Cs. melanura remained detectable when a single infected mosquito was triturated in a pool with 99 uninfected mosquitoes. These results show that in BHK or Vero cell culture assay systems, triturated Cs. melanura do not completely prevent the detection of EEE virus. The results therefore indicate that mosquito suspensions would not interfere with the isolation of virus from field-collected mosquitoes. This conclusion suggests that mosquito suspensions were not a factor in previous studies that were unsuccessful at detecting transovarial transmission of EEE virus by Cs. melanura.

Alphavirus↗
PubMed1989

Experimental transmission of Crimean-Congo hemorrhagic fever virus by Hyalomma truncatum Koch.

Larval Hyalomma truncatum ticks were infected with Crimean-Congo hemorrhagic fever (CCHF) virus by allowing them to engorge on viremic newborn mice. The overall tick infection rate was 4.4% (24/542). Virus was detected in specimens for greater than or equal to 160 days postinfection. Transstadial transmission to the adult tick stage was observed and horizontal transmission to a mammalian host was demonstrated. Horizontal transmission of CCHF virus to uninfected adult ticks occurred while feeding with transstadially infected ticks on the same host. No evidence of transovarial virus transmission from infected female ticks to their 1st generation progeny was observed.

Animals↗
PubMed1989

Experimental infection of six species of ixodid ticks with Dugbe virus (family Bunyaviridae, genus Nairovirus).

The vector potential of each of 6 species of colonized North American and African ixodid ticks was assessed by intracoelomic inoculation with Dugbe virus (IbAr 1792, 14th passage in suckling mouse brain) and viral titers were monitored after selected incubation periods. Persistence of Dugbe virus for greater than or equal to 53 days in 5 species (Dermacentor andersoni, D. variabilis, Amblyomma americanum, Rhipicephalus appendiculatus, and R. sanguineus) indicates that infection occurred. Viral titers were significantly higher in female vs. male D. variabilis, R. appendiculatus, and A. americanum after blood feeding. Blood feeding had no significant effect on the viral titers of either female or male R. sanguineus. D. andersoni males also exhibited no significant change in viral titers after blood-feeding, but 100% (20/20) of drop-off females and 96% (24/25) of post-oviposition females (36 days postinoculation) contained no detectable virus even though virus was still found in unfed specimens less than or equal to 124 days postinoculation. Virus was not recovered from greater than 30,000 1st generation progeny (eggs, larvae, nymphs, adults) collected as eggs from inoculated female D. andersoni, D. variabilis, R. sanguineus, and R. appendiculatus 27-51 days postinoculation. R. sanguineus and R. appendiculatus transmitted Dugbe virus to guinea pigs when allowed to feed 1-3 weeks postinoculation.

Africa↗
PubMed1989

Inhibition of Crimean-Congo hemorrhagic fever viral infectivity yields in vitro by ribavirin.

Ribavirin was evaluated as a potential therapeutic for Crimean-Congo hemorrhagic fever (CCHF). Viral yields for strains of CCHF virus from Europe, Asia, and Africa in African green monkey kidney (Vero) cells were markedly reduced by this drug. Some CCHF viral strains appeared more sensitive than others, but in general, ribavirin doses as low as 5 micrograms/ml caused a transient reduction of viral yields. A further reduction in viral yields was induced by a dose of 25 micrograms/ml, and evidence of viral replication was not demonstrated in cells treated with 50 or 250 micrograms/ml. In contrast, a dose of ribavirin at least 9 times greater was required to induce a comparable inhibitory effect on the yields of Rift Valley fever virus, for which the drug has been shown to inhibit replication in monkeys and rodents.

Animals↗
PubMed1988

Experimental infection of Phlebotomus papatasi with sand fly fever Sicilian virus.

Experimental studies were conducted to evaluate humans as hosts infecting the sand fly Phlebotomus papatasi with sand fly fever Sicilian (SFS) virus. Viral antigen and infectious virus circulated in the blood of infected volunteers on days 4 and 5 after intravenous inoculation with SFS virus. Viremia levels during the latter period were high enough to infect feeding sand flies, but only 13% (9/69) of the flies became infected. One out of every 3 infected sand flies that survived to feed a second time transmitted SFS to a hamster. These results confirm a vertebrate-sand fly-vertebrate transmission cycle for SFS virus, and demonstrate that horizontal transmission may contribute to the maintenance of this virus in nature.

Animals↗