G T Strickland

University of Maryland, Baltimore, Baltimore, Maryland, United States

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Publications (115)759.73 Total impact

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    ABSTRACT: To date, there is no licensed Hepatitis C Virus (HCV) vaccine and what constitutes a protective immune response or correlate of protection against HCV infection is still vague. The Egyptian case of HCV is unique with a prevalence of ~15% among the general population and ~90 of the isolates belonging to genotype 4. This constitutes a great risk for Egyptian healthcare workers (HCW). The National Liver Institute (NLI) is a teaching hospital that focuses its clinical practice and research on liver diseases with ~1500 employees. The NLI receives ~125,000 outpatient visits and admits ~15,000 patients/year. Over 85% of the adult patients attending the facility have anti-HCV antibodies, and 65%-75% of them are also viremic. HCV spontaneous clearance occurs in 15%-50% of infected subjects indicating that natural resistance to chronic infection exists. The mechanisms behind successful HCV clearance suggest the coordination of multiple arms of the immune system, with cell-mediated immunity (CMI) playing a crucial role in this process. We reported an anti-HCV prevalence of 16.6% among the NLI HCW and 72.1% of them were viremic. HCV incidence was 2.04/1000 person-years and incidence was high (4.8%) among needle-stick injury subjects. Interestingly, >25% of these HCW demonstrated strong HCV multi-specific CMI without viremia or seroconversion, suggesting clearance of low HCV infection(s). IL28B. rs12979860 predicted the outcome of HCV infection among these HCW (p0.05). In conclusion, the Egyptian HCW could be ideal subjects for HCV vaccine trials and correlates of protection could be closely monitored among them. Copyright
    No preview · Article · Jan 2016 · JAIDS Journal of Acquired Immune Deficiency Syndromes
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    ABSTRACT: Hepatitis C Virus (HCV) infection is a global health burden particularly in Egypt, where HCV genotype 4a (GT-4a) predominates. The prevention and control of HCV infection will remain a challenge until the development of an effective vaccine that protects against different genotypes. Several HCV GT-1-based vaccines are in different stages of clinical trials, but antigenic differences could make protection against other genotypes problematic. In this regard, data comparing the cell-mediated immune (CMI) response to different HCV genotypes are limited. We aimed to ex vivo investigate whether GT-1-based vaccine may protect against HCV GT-4 infections. This was carried out on samples collected from genotype 4 infected/exposed subjects.
    Full-text · Article · Jun 2014 · PLoS ONE
  • G Thomas Strickland · Samer S El-Kamary

    No preview · Chapter · Dec 2013
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    ABSTRACT: BACKGROUND: Hepatitis C virus (HCV) is a global health threat with Egypt having the highest worldwide prevalence. Evaluation of the efficacy of a preventive HCV vaccine, such as those currently in Phase I/II trials, requires a cohort with a high-risk exposure to HCV. OBJECTIVE: To identify a reliable cohort for evaluating preventive HCV vaccines, we studied HCV incidence among HCW in a hospital where almost 85% of patients are HCV-infected. STUDY DESIGN: Of 717 HCW negative for HCV-antibodies (anti-HCV) at baseline, 651 were followed up and tested for seroconversion twice annually for an average of 504±154days. Those reporting a needle-stick injury were additionally tested for both HCV antibodies and RNA monthly for a total of four months. RESULTS: Two subjects (0.31%) had anti-HCV and HCV-RNA seroconversion with an overall incidence of 2.04/1000 person-years and a 4.8% incidence among the 21 subjects who reported a needle-stick injury. Two additional subjects had viremia without detectable anti-HCV. Two of the four subjects were among 21 with reported needle-stick injuries (9.5%) and another had surgery. All four were nurses providing direct patient care. CONCLUSIONS: Our results show that both transient and persistent viremia were detectable in this high-risk cohort of HCW and suggest that absence of anti-HCV in two of the subjects may be due to low-dose viral exposures. These data indicate that HCV infections acquired from documented injuries during direct patient care are frequent in Egypt and can guide selection of eligible HCW suitable for preventive HCV vaccine trials.
    Full-text · Article · Jan 2013 · Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology
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    ABSTRACT: Objective To investigate the association between hepatitis C virus (HCV)-specific cell-mediated immunity (CMI) responses and viral clearance in children born to mothers infected with HCV. Study design A cross-sectional study of children from a mother-infant cohort in Egypt were enrolled to detect CMI responses to recombinant core and nonstructural HCV antigens (nonstructural segments NS3, NS4a/b, and NS5 of the HCV genome) using an interferon-gamma enzyme-linked immunospot assay. Children born to mothers with chronic HCV were enrolled into 3 groups: transiently viremic (n = 5), aviremic (n = 36), and positive control (n = 6), which consisted of 1 child with chronic HCV from this cohort and another 5 children with chronic HCV from a companion study. Children without HCV born to mothers without HCV (n = 27) served as a negative control group. Wilcoxon rank sum test was used to compare the magnitude of CMI responses between groups. Results None of the 6 control children who were positive for HCV responded to any HCV antigen, and 4 (80%) of 5 children with transient viremia responded to at least one HCV antigen, compared with 5 (14%) of 36 and 3 (11%) of 27 children in the aviremic and negative control groups, respectively. Children with transient viremia elicited stronger responses than did negative controls (P = .005), positive controls (P = .011), or children without HCV viremia (P = .012), particularly to nonstructural antigens. Conclusions HCV-specific CMI responses were significantly higher in magnitude and frequency among transiently infected children compared with those persistently infected. This suggests CMI responses may be associated with past viral clearance and can identify children at high risk of infection, who can be targeted for health education, screening, and follow-up.
    Full-text · Article · Aug 2012 · The Journal of pediatrics
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    ABSTRACT: Little is known about the prevalence of hepatitis C virus (HCV) among healthcare workers (HCW) in Egypt, where the highest worldwide prevalence of HCV exists. The prevalence of HCV, hepatitis B virus and Schistosoma mansoni antibodies was examined in 842 HCWs at the National Liver Institute in the Nile Delta, where >85% of patients are HCV antibody-positive. The mean age of HCWs was 31.5 years and they reported an average of 0.6±1.2 needlesticks/HCW/year. The prevalence of anti-HCV, hepatitis B surface antigen (HBsAg) and co-infection was 16.6%, 1.5% and 0.2%, respectively. HCV-RNA was present in 72.1% of anti-HCV-positive HCWs, and all but one subject were infected with HCV genotype 4. Schistosoma mansoni antibodies were present in 35.1%. The anti-HCV rate increased sharply with age and employment duration, but not among those with needlestick history. After adjusting for other risk factors, the anti-HCV rate was higher among older HCWs [P<0.001; risk ratio (RR) = 1.086, 95% CI 1.063-1.11], males (P=0.002; RR=1.911, 95% CI 1.266-2.885) and those with rural residence (P<0.001; RR=2.876, 95% CI 1.830-4.52). Occupation (P=0.133), duration of employment (P=0.272) or schistosomal antibody positivity (P=0.152) were not significant risk factors for anti-HCV positivity. In conclusion, although one in six HCWs had been infected with HCV, the infections were more likely to be community-acquired and not occupationally related.
    Full-text · Article · Dec 2011 · Transactions of the Royal Society of Tropical Medicine and Hygiene

  • No preview · Article · Apr 2011 · JAIDS Journal of Acquired Immune Deficiency Syndromes
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    ABSTRACT: Cell-mediated immune (CMI) responses to hepatitis C virus (HCV) antigens in adults without seroconversion or viremia are biomarkers for prior transient infection. We investigated HCV-specific CMI responses in seronegative children living with HCV-infected siblings. Children 3-18 years of age living with HCV-infected siblings were screened for HCV antibodies and HCV RNA. Peripheral blood mononuclear cells (PBMCs) were evaluated for HCV-specific CMI responses by interferon γ (IFN-γ) enzyme-linked immunospot assay using 3 recombinant HCV protein antigens. Flow cytometry phenotypically characterized IFN-γ-secreting cells. Forty-five seronegative children and 5 seropositive viremic siblings had functionally viable PBMCs. Among the 45 seronegative siblings, 15 (33.3%) had positive HCV-specific IFN-γ responses, and subsequent RNA testing revealed that 3 were viremic. Compared with the 5 seropositive viremic children, the median number of HCV-specific spot-forming units was significantly higher in the 12 seronegative aviremic children (P = .002) and in the 3 seronegative viremic children (P = .025). Flow cytometric analysis revealed that IFN-γ was synthesized mainly by CD4(+) T cells. Strong HCV-specific CD4(+) T cell responses were detectable in higher frequency among seronegative, aviremic children compared with persistently infected siblings. Further studies are needed to determine whether these immune responses are protective against HCV infection.
    Full-text · Article · Mar 2011 · The Journal of Infectious Diseases
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    G Thomas Strickland

    Preview · Article · Oct 2010 · Clinical Infectious Diseases
  • G T Strickland

    No preview · Article · May 2010 · Journal of Viral Hepatitis
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    ABSTRACT: A prospective study in three Egyptian villages (A, B and C) having a high prevalence of hepatitis C virus (HCV) infection examined incidence of community-acquired HCV infection in children; 2852 uninfected infants were prospectively followed from birth for up to 5.5 years. Fifteen seroconverted for either HCV antibodies and/or HCV-RNA (incidence of 0.53%). Ten had both anti-HCV and HCV-RNA; four had only anti-HCV; and one had HCV-RNA in the absence of antibody. The incidence rate at all ages was 2.7/1000 person-years (PY). It was 3.8/1000 PY during infancy and 2.0/1000 PY for the 1-5-years age group. Hospitalization and low birth weight increased the risk of infection; while living in village B, the family having a higher socioeconomic status, and advanced maternal education were protective. Six of eight HCV-infected infants reported iatrogenic exposures (e.g. hospitalization, therapeutic injections, ear piercing) prior to infection whereas only 2/7 children older than 1 year reported these exposures. Having an HCV-positive mother was the only other reported risk in two of these older children. The virus cleared in six (40%) children by the end of follow-up. Health education targeting iatrogenic exposures and focusing on risk factors could reduce HCV infection in children in high-risk populations.
    Full-text · Article · Feb 2010 · Transactions of the Royal Society of Tropical Medicine and Hygiene
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    ABSTRACT: Although persistent transmission of hepatitis C virus (HCV) from infected mothers to their infants is reported in 4-8%, transient HCV perinatal infection also occurs. This prospective cohort study determined perinatal HCV infection- and early and late clearance-rates in 1,863 mother-infant pairs in rural Egyptian villages. This study found 15.7% and 10.9% of pregnant women had HCV antibodies (anti-HCV) and HCV-RNA, respectively. Among 329 infants born of these mothers, 33 (10.0%) tested positive for both anti-HCV and HCV-RNA 2 months following birth-29 (12.5%) having HCV-RNA positive mothers and 4 (with transient infections) having mothers with only anti-HCV. Fifteen remained HCV-RNA positive at one and/or 2 years (persistent infections), while 18 cleared both virus and antibody by 1 year (transient infections). Among the 15 persistent cases, 7 cleared their infections by 2 or 3 years. At 2- to 6- and at 10- to 12-month maternally acquired anti-HCV was observed in 80% and 5% of infants, respectively. Four perinatally infected and one transiently infected infant were confirmed to be infected by their mothers by the sequence similarity of their viruses. Viremia was 155-fold greater in mothers of infants with persistent than mothers of infants with transient infections. Maternal-infant transmission of HCV is more frequent than generally reported. However, both early and late clearance of infection frequently occurs and only 15 (4.6%) and 8 (2.4%) infants born of HCV-RNA positive mothers had detectable HCV-RNA at one and 2-3 years of age. Investigating how infants clear infection may provide important information about protective immunity to HCV.
    Full-text · Article · Jun 2009 · Journal of Medical Virology
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    ABSTRACT: Milk thistle or its purified extract, silymarin (Silybum marianum), is widely used in treating acute or chronic hepatitis. Although silymarin is hepatoprotective in animal experiments and some human hepatotoxic exposures, its efficacy in ameliorating the symptoms of acute clinical hepatitis remains inconclusive. In this study, our purpose was to determine whether silymarin improves symptoms, signs and laboratory test results in patients with acute clinical hepatitis, regardless of etiology. This is a randomized, placebo-controlled trial in which participants, treating physicians and data management staff were blinded to treatment group. The study was conducted at two fever hospitals in Tanta and Banha, Egypt where patients with symptoms compatible with acute clinical hepatitis and serum alanine aminotransferase (ALT) levels >2.5 times the upper limit of normal were enrolled. The intervention consisted of three times daily ingestion of either a standard recommended dose of 140 mg of silymarin (Legalon, MADAUS GmbH, Cologne, Germany), or a vitamin placebo for four weeks with an additional four-week follow-up. The primary outcomes were symptoms and signs of acute hepatitis and results of liver function tests on days 2, 4 and 7 and weeks 2, 4, and 8. Side-effects and adverse events were ascertained by self-report. From July 2003 through October 2005, 105 eligible patients were enrolled after providing informed consent. No adverse events were noted and both silymarin and placebo were well tolerated. Patients randomized to the silymarin group had quicker resolution of symptoms related to biliary retention: dark urine (p=0.013), jaundice (p=0.02) and scleral icterus (p=0.043). There was a reduction in indirect bilirubin among those assigned to silymarin (p=0.012), but other variables including direct bilirubin, ALT and aspartate aminotransferase (AST) were not significantly reduced. Patients receiving silymarin had earlier improvement in subjective and clinical markers of biliary excretion. Despite a modest sample size and multiple etiologies for acute clinical hepatitis, our results suggest that standard recommended doses of silymarin are safe and may be potentially effective in improving symptoms of acute clinical hepatitis despite lack of a detectable effect on biomarkers of the underlying hepatocellular inflammatory process.
    Full-text · Article · Mar 2009 · Phytomedicine: international journal of phytotherapy and phytopharmacology

  • No preview · Article · Jan 2009 · The Lancet Infectious Diseases
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    ABSTRACT: Despite difficulties associated with extreme variability and mutability of hepatitis C virus (HCV), several vaccines that prevent initial infection or viral persistence, or that clear viraemia in individuals with chronic HCV infections, are currently in development. At least one vaccine that may prevent chronic persistent infections will soon be available for testing. We review the widespread importance of HCV infection and disease, the immune response to HCV and correlates of protection, prevention strategies and vaccine candidates, and groups that will need the vaccine and provide suitable populations for assessing vaccine safety and efficacy. The evaluation of prophylactic vaccines is particularly problematic since distribution must focus upon individuals at high risk of exposure-for example, intravenous drug users and health-care providers in areas with high HCV prevalence. Although there is a huge need for therapeutic vaccines, further immunological hurdles must be cleared before one becomes available.
    No preview · Article · Jul 2008 · The Lancet Infectious Diseases
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    ABSTRACT: A prospective cohort study of the incidence and risk factors for hepatitis C virus (HCV) infection was performed in 2171 pregnant women in three rural Egyptian villages who were HCV antibody (anti-HCV) and RNA (HCV-RNA) negative at baseline. During an average of 2.2 years follow up, 25 incident cases were observed, giving an estimated HCV incidence of 5.2/1000 person-years (PY). The infection rate correlated with community anti-HCV prevalence in pregnant women, while the perinatal incidence rate of 11.2/1000 PY was almost five times that of the non-perinatal rate (2.3/1000 PY). The data suggested iatrogenic perinatal risk factors were associated with infection in one village, while health education reduced infections in another. Among the 25 incident cases, eight were HCV-RNA negative when they were first found to be anti-HCV positive and one-third of the 15 viraemic cases with follow-up data available cleared their HCV-RNA after an average of 1.3 years. None of the 25 incident cases were jaundiced or had symptoms of hepatitis but elevated serum alanine aminotransferase levels confirmed hepatitis in nine. Our data suggest that asymptomatic HCV infections frequently occurred during the perinatal period but often cleared and that educating medical personnel on safe practices possibly reduced HCV transmission.
    Full-text · Article · Jun 2008 · Transactions of the Royal Society of Tropical Medicine and Hygiene
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    André R S Périssé · G Thomas Strickland
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    ABSTRACT: In areas of low-to-moderate risk of malaria transmission, the World Health Organization recommends parasitic confirmation before treatment. Such areas have usually low budget for health care and malaria diagnosis is mostly based on clinical assumption. Algorithms have been developed to improve health care providers' identification of clinical malaria and could be used as screening to reduce the number of individuals requiring parasitic confirmation before treating. Prospective clinical and parasitological data were collected from inhabitants of four villages from March 1984 through March 1985. Symptoms and signs recorded by physicians were used in multivariate models to test the best predictors of malaria. Sensitivity and specificity were calculated for various cut-offs of scores and compared to clinical diagnosis. A total of 8.941 individuals were evaluated during the 1-year period of data collection. The overall prevalence of malaria parasitemia was 19.7% (n=1762). Of the 4280 people evaluated during the high season period, 24% (n=1024) presented any parasitemia, 55.3% (566/1024) due to Plasmodium falciparum. The final clinical algorithm included history of fever, rigors, headache, absence of myalgia, backache or cough, nausea or vomiting, and splenomegaly on examination as predictable variables. At a cut-off score of 2.0, the sensitivity of the algorithm was higher for the entire sample (57% vs. 43%), for high season period (70% vs. 53%), for children less than 6 years of age (59% vs. 40%), for individuals with parasitemia due to P. falciparum (65% vs. 48%), and for high P. falciparum parasitemic individuals at high season (84% vs. 68%). However, specificity was usually lower unless a higher cut off was used, in which case the gain in sensitivity by using the algorithm was reduced. In low-to-moderate transmission areas in which health related resources are scarce, a clinical algorithm increases the identification of real cases of malaria and could be used as screening for further parasitic identification.
    Preview · Article · Jun 2008 · Acta tropica
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    ABSTRACT: To determine whether human herpesvirus 8 (HHV-8) is associated with schistosomal and hepatitis C virus infections in Egypt, we surveyed 965 rural household participants who had been tested for HHV-8 and schistosomal infection (seroprevalence 14.2% and 68.6%, respectively, among those <15 years of age, and 24.2% and 72.8%, respectively, among those > or =15 years of age). Among adults, HHV-8 seropositivity was associated with higher age, lower education, dental treatment, tattoos, > or =10 lifetime injections, and hepatitis C virus seropositivity. In adjusted analyses, HHV-8 seropositivity was associated with dental treatment among men (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1-5.2) and hepatitis C virus seropositivity among women (OR 3.3, 95% CI 1.4-7.9). HHV-8 association with antischistosomal antibodies was not significant for men (OR 2.1, 95% CI 0.3-16.4), but marginal for women (OR 1.5, 95% CI 1.0-2.5). Our findings suggest salivary and possible nosocomial HHV-8 transmission in rural Egypt.
    Full-text · Article · Apr 2008 · Emerging Infectious Diseases
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    ABSTRACT: Little is known about mothers' perspectives and experiences of early breast-feeding cessation as a strategy to reduce postnatal HIV transmission in rural, resource-constrained settings. We conducted in-depth interviews (IDI) with 15 HIV-positive breast-feeding mothers of infants aged 3-5 mo about their plans for feeding their infants after age 6 mo. We also conducted IDI with 12 HIV-positive mothers who intended to stop breast-feeding after receiving their infant's HIV-PCR negative test result at age 6 mo. Twenty-four-hour dietary recalls were conducted with the same 12 mothers and 16 HIV-negative or status unknown mothers who were breast-feeding their 6- to 9-mo-old infants. Of the 12 mothers who intended to stop breast-feeding, 11 did so by 9 mo. Median energy intake (percent requirement) was 1382 kJ (54%) among weaned infants compared with 2234 kJ (87%) among breast-feeding infants. Median intakes were <67% of the recommended levels for 9 and 7 of the 12 micronutrients assessed for weaned and breast-feeding infants, respectively. Factors facilitating early breast-feeding cessation were mothers' knowledge about HIV transmission, family support, and disclosure of their HIV status; food unavailability was the primary barrier. HIV-positive mothers in resource-constrained settings may be so motivated to protect their child from HIV that they stop breast-feeding early even when they cannot provide an adequate replacement diet. As reflected in the new World Health Organization guidance, HIV-positive mothers should continue breastfeeding their infants beyond 6 mo if replacement feeding is still not acceptable, feasible, affordable, sustainable, and safe.
    Full-text · Article · Mar 2008 · Journal of Nutrition
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    ABSTRACT: In developing countries, hepatitis E (HEV) and hepatitis A (HAV) are the major causes of acute viral hepatitis with similar feco-oral modes of transmission. In contrast to the high seroprevalence of hepatitis A infection, a low seroprevalence of HEV among children in endemic areas has been reported. These data suggest the possibility that silent HEV infection is undiagnosed by the current available methods. Many of the serological tests used for HEV diagnosis have poor specificity and are unable to differentiate among different genotypes of HEV. Moreover, the RT-PCR used for HEV isolation is only valid for a brief period during the acute stage of infection. Cell-mediated immune (CMI) responses are highly sensitive, and long lasting after sub-clinical infections as shown in HCV and HIV. Our objective was to develop a quantitative assay for cell-mediated immune (CMI) responses in HEV infection as a surrogate marker for HEV exposure in silent infection. Quantitative assessment of the CMI responses in HEV will also help us to evaluate the role of CMI in HEV morbidity. In this study, an HEV-specific interferon-gamma (IFN-gamma) ELISPOT assay was optimized to analyze HEV-specific CMI responses. We used peripheral blood mononuclear cells (PBMC) and sera from experimentally infected chimpanzees and from seroconverted and control human subjects to validate the assay. The HEV-specific IFN-gamma ELISPOT responses correlated strongly and significantly with anti-HEV ELISA positive/negative results (rho=0.73, p=0.02). Moreover, fine specificities of HEV-specific T cell responses could be identified using overlapping HEV ORF2 peptides.
    Full-text · Article · Jan 2008 · Journal of Immunological Methods

Publication Stats

4k Citations
759.73 Total Impact Points

Institutions

  • 1985-2014
    • University of Maryland, Baltimore
      • • Department of Epidemiology and Public Health
      • • Department of Medicine
      Baltimore, Maryland, United States
  • 1988-2013
    • University of Maryland Medical Center
      Baltimore, Maryland, United States
  • 1992-2007
    • Assiut University
      • Faculty of Medicine
      Lycopolis, Asyūţ, Egypt
  • 2004
    • University of Maryland, College Park
      CGS, Maryland, United States
  • 1989-2003
    • Cairo University
      • Faculty of Medicine
      Al Qāhirah, Muḩāfaz̧at al Qāhirah, Egypt
    • Ain Shams University
      • Faculty of Medicine
      Al Qāhirah, Muḩāfaz̧at al Qāhirah, Egypt
  • 2000
    • Loyola University Maryland
      Baltimore, Maryland, United States