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Biomedical subjects

N T Constantine

Publications and source records attributed to N T Constantine.

At least 55 records · Page 3Linked to original sources
PubMed1992

The epidemiology of hepatitis C virus antibody in Yemen.

A cross-sectional survey of 348 subjects without evidence of liver disease was conducted to investigate the prevalence and risk factors for hepatitis C virus antibody (anti-HCV) seropositivity in the Yemen Arab Republic. The mean age of study subjects was 28.7 years (range 3-80), and 61% were males. Using commercial enzyme-linked immunosorbent assays (ELISA), 6.0% (95% confidence interval [CI] 3.8-9.1) of subjects were anti-HCV-positive, 13.5% were hepatitis B surface antigen-positive (HBsAg-positive), and 51.4% were positive for at least one serologic marker of prior hepatitis B infection. Nine (2.6%; 95% CI 1.2-4.9) of the 21 ELISA-positive sera were confirmed to be anti-HCV positive by a recombinant immunoblot assay. Anti-HCV seropositivity was significantly associated with age (odds ratio [OR] 2.0 for each 10-year increase in age) and prior surgery (OR 10.1), but was not associated with a history of prior blood transfusion or markers of hepatitis B infection. These preliminary data suggest that hepatitis C may pose a substantial health threat in Yemen.

Adolescent↗
PubMed1992

Monitoring for HIV-1, HIV-2, HTLV-I sero-progression and sero-conversion in a population at risk in east Africa.

Thirty-three individuals from East Africa, at risk for acquiring sexually transmitted infections, were selected to be monitored over a five month period for evidence of sero-progression and/or sero-conversion for human immunodeficiency virus type-1 and type-2 (HIV-1, HIV-2), and human T cell leukemia virus type-1 (HTLV-I). Initially, all sera were reactive by at least one retroviral screening assay, but most produced negative or indeterminate results by western blot assays. Five months after the initial screening, western blot assays indicated that one individual exhibited full sero-conversion for HIV-1; one HIV-1 positive individual also became positive for HIV-2; and two subjects showed sero-progression to become HTLV-I confirmed positive. Sera from fourteen individuals produced indeterminate results by western blot for HIV-1, ten of which were previously negative; the remaining four sera exhibited reactivity to at least one additional viral specific antigen after the five months. Circulating HIV-1 antigen was not demonstrated in any of the sera but DNA isolated from one of the individuals with indeterminate results produced a positive reaction for HIV-1 by the polymerase chain reaction.

Blotting, Western↗
PubMed1992

Diagnostic challenges: lymphotropic sero-"questionables".

During a sero-survey for lymphotropic retroviruses, seven screening tests were performed for the three lymphotropic retroviruses of relevance in Djibouti, East Africa (HIV-1, HIV-2 and HTLV-1). Of the 82 subjects whose sera reacted in at least one retroviral screening assay, about one third could be followed, and their sera were re-examined after a 5-month interval, and then after an additional 3-month interval. Six selected individuals are reported here, whose retroviral serologies presented important and often unexplained changes over an eight-month period. The six cases summarize prototypic situations and present serological results in a style appropriate to stimulate thought on the significance and interpretation of lymphotropic viral serologies. Each case study is followed by a set of questions that formulate pertinent serological concepts.

Adult↗
PubMed1991

A serosurvey for HTLV-I among high-risk populations and normal adults in Egypt.

The prevalence of antibodies to human T-cell lymphotropic virus type I (HTLV-I) was determined in high-risk groups and normal adults in Egypt. Among 647 individuals tested, 6 (0.9%) were confirmed positive by western blot analysis. These included 2 (0.7%) of 279 drug addicts, 1 (3.3%) of 30 patients with sexually transmitted diseases, and 3 (2.2%) of 133 healthy individuals. Antibody was not detected in 47 blood recipients or 158 prostitutes. There was no correlation between sex or geographical location and HTLV-I infection. Fifty-three of the 647 sera (8%) were initially reactive by ELISA, but only 12 sera were repeatedly reactive. Since only 4 of these repeatedly reactive sera were confirmed by the western blot, the frequency of false positives using the DuPont screening ELISA was 1.2% (8/643). Two additional sera, confirmed positive by western blot, had been reactive, but not repeatedly, by ELISA. In comparison to the prevalence of HTLV-I antibody among risk groups in many parts of the world, the prevalence in Egypt was low.

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

Serological evidence for human immunodeficiency virus type 2 in east Africa.

Infection by human immunodeficiency virus type 2 (HIV-2) has not previously been described in North or East Africa. We examined over 1200 sera of high-risk individuals from three North/East African countries for antibodies to HIV-2. Results indicated that 17 were repeatedly reactive by ELISA; 4 were confirmed by Western blot. Of the 4 confirmed, 2 produced strong reactions to the envelope antigens of HIV-2 but not of HIV-1. One of these subjects was a foreigner from Senegal who was tested while in Egypt and one was a Djiboutian prostitute who was infected presumably prior to October 1987. We conclude that HIV-2 has been introduced into this region and that specific testing of selected individuals for HIV-2 is warranted.

Adult↗
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

Are tuberculosis wards a risk factor for HIV in Africa?

A twenty-year-old female prostitute had an indeterminant HIV western blot in Djibouti during June 1988. She was hospitalised at the tuberculosis hospital in October and was re-tested for HIV in November. Her western blot result was still indeterminant, despite a progressive profile, and she therefore escaped to the hospital's HIV surveillance system. There were strong indications that while in-hospital, the patient resumed the activities of her previous profession. We conclude that active tuberculosis may develop in African HIV patients prior to the development of a confirmatory HIV western blot profile. Thorough precautionary measures are indicated for preventing HIV from spreading to health care personnel and amongst hospitalised patients in Africa.

Adult↗
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

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

Diagnostic usefulness of five screening assays for HIV in an east African city where prevalence of infection is low.

Five commercial screening assays for HIV-1, evaluated for their usefulness in detecting infection in high-risk groups in the East African country of Djibouti, produced varying degrees of performance when compared to Western blot and immunofluorescence confirmatory assays. In this population with a low prevalence of HIV infection (16/599), two enzyme-linked immunosorbent assays (ELISA; Abbott and Elavia) and two rapid assays (cambridge latex agglutination and Du Pont's HIV-CHEK) exhibited less than optimal sensitivities. However, with the exception of Elavia, these assays displayed excellent specificities. The fifth test (Serodia gelatin agglutination) produced the highest sensitivity (0.938) and negative predictive value but the lowest specificity and positive predictive value of all five tests. False positive reactions, which occurred only with the Elavia and Serodia tests, could not be explained on the basis of early infection in patients or cross-reactions with the related retroviruses HIV-2 and HTLV-I. We conclude that none of the five tests alone is sufficient in this testing situation, but that a combination of tests could satisfy most requirements for identifying HIV-1 reactive and non-reactive sera.

AIDS Serodiagnosis↗
PubMed1989

HIV-1 and hepatitis B transmission in Sudan.

A seroepidemiologic survey was conducted among 773 male soldiers living in five urban locations in Sudan to study the prevalence of and risk factors for HIV-1 and hepatitis B transmission. Twenty-eight per cent of the study population were born and raised in southern Sudan, an area bordering Kenya, Zaire and Uganda, whilst 72% of the study subjects were from northern Sudan. Seventy-eight per cent of the study population had serologic evidence of past hepatitis B infection, and 13 soldiers were confirmed positive for HIV-1 antibody. All 13 HIV-positive soldiers had recently been deployed in southern Sudan. Multivariate analysis indicated an association between living in southern Sudan and both hepatitis B (odds ratio 8.2) and HIV-1 infection (odds ratio 14). Additionally, sexual relations with prostitutes (odds ratio 1.5) and medical injections for schistosomiasis (odds ratio 2.72) were independent predictors of hepatitis B markers in this military population. The findings of this study suggest that sexual promiscuity is a risk factor for hepatitis B transmission in Sudan. They also indicate one possible route for the spread of HIV-1 from central to northern Africa.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Hepatitis B and HIV in Sudan: a serosurvey for hepatitis B and human immunodeficiency virus antibodies among sexually active heterosexuals.

A serosurvey was conducted in Port Sudan and Suakin, Sudan in October and March 1987 to determine the prevalence and risk factors associated with the transmission of hepatitis B, human immunodeficiency virus type 1 (HIV-1), and syphilis among sexually active heterosexuals on the coast of Sudan. A total of 536 subjects, including 202 female prostitutes, 95 long-distance truck drivers, 103 soldiers, 72 Ethiopian refugees, and 54 Sudanese outpatients, were enrolled in the study. Seventy-eight percent (202/259) of the female study subjects were engaged in prostitution, and 57% (157/277) of the men admitted to prior sexual relations with prostitutes. Serologic markers for hepatitis B and syphilis were detected in 68% and 17% of the entire study population, respectively. In contrast, antibody to HIV-1 was detected in none of the 536 sera tested. Risk factors found to be independently predictive of hepatitis B infection by multivariate analysis included prostitution, positive serology for syphilis, and a history of anti-schistosomal therapy. The absence of HIV-1 infection among the prostitutes enrolled in this study is in marked contrast to the current AIDS epidemic in neighboring sub-Saharan countries, suggesting that HIV-1 has not been widely introduced on the coast of Sudan. The high prevalence of serologic markers to hepatitis B and syphilis, however, indicates a potential for HIV-1 in this region.

Adolescent↗