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Dive into the research topics where Robert W. Ryder is active.

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Featured researches published by Robert W. Ryder.


AIDS | 1991

Evidence of marked sexual behavior change associated with low HIV-1 seroconversion in 149 married couples with discordant HIV-1 serostatus: experience at an HIV counselling center in Zaire.

Munkolenkole Kamenga; Robert W. Ryder; Muana Jingu; Nkashama Mbuyi; Lubamba Mbu; Frieda Behets; Christopher Brown; William L. Heyward

To determine the effect of an HIV-1 counselling program on 149 married Zairian couples with discordant HIV-1 serology, the rates of HIV-1 seroconversion and reported condom utilization have been observed during 382.4 person-years of follow-up (minimum follow-up time per couple of 6 months). Before determination of HIV-1 serostatus and counselling, less than 5% of these couples had ever used a condom. One month after notification of HIV-1 serostatus and counselling, 70.7% of couples reported using condoms during all episodes of sexual intercourse. At 18 months follow-up, 77.4% of the 140 couples still being followed reported continued use of condoms during all episodes of sexual intercourse. At the time of notification of HIV-1 serostatus, 18 couples experienced acute psychological distress. Home-based counselling by trained nurses resolved these difficulties in all but three couples who subsequently divorced. Intensive counselling following notification of HIV-1 serostatus led to low rates of HIV-1 seroconversion (3.1% per 100 person-years of observation) in Zairian married couples with discordant HIV-1 serostatus who voluntarily attended an HIV counselling center.


The Lancet | 1993

Spectrum of immunodeficiency in HIV-1-infected patients with pulmonary tuberculosis in Zaire.

Y.B. Mukadi; J.H Perriëns; M.E St Louis; C. Brown; Robert W. Ryder; Françoise Portaels; Peter Piot; J-C Willame; Jacques Prignot; F. Pouthier; M Kaboto

Tuberculosis (TB) is the most common opportunistic infection in African patients who die from AIDS, yet the stage of immunodeficiency at which TB develops is uncertain. We studied the immune status of HIV-infected outpatients with pulmonary TB in relation to their clinical presentation in a cross-sectional study of 216 HIV-seropositive and 146 HIV-seronegative ambulatory incident cases of smear-positive and culture-positive pulmonary TB in Kinshasa, Zaire. HIV-seropositive and seronegative patients had median CD4 lymphocyte counts of 316.5/microL and 830.5/microL, respectively. Of the HIV-seropositive patients, 32.9% had less than 200 CD4 lymphocytes/microL, 37% between 200 and 499, and 30.1% 500 or more. Clinical AIDS, as defined by the WHO clinical case-definition or a modified version, was of similar limited use as a predictor of immunodeficiency. Among HIV-seropositive patients, oral candidosis, lymphopenia, a negative tuberculin purified protein derivative test, and cutaneous anergy were strongly associated with CD4 counts of less than 200/microL, and seemed to be better markers of immune dysfunction. We conclude that pulmonary TB develops across a broad spectrum of HIV-induced immunodeficiency and that a diagnosis of pulmonary TB is of limited use as a marker of stage of HIV disease in African HIV-infected outpatients.


The New England Journal of Medicine | 1991

Plasmodium Falciparum malaria and perinatally acquired human immunodeficiency virus type 1 infection in Kinshasa, Zaire. A prospective, longitudinal cohort study of 587 children.

Alan E. Greenberg; Wato Nsa; Robert W. Ryder; Mvula Medi; Matadi Nzeza; Nsimba Kitadi; Matela Baangi; Nsuami Malanda; Farzin Davachi; Susan E. Hassig

BACKGROUND It is uncertain whether Plasmodium falciparum malaria is more frequent or more severe in children with perinatally acquired human immunodeficiency virus type 1 (HIV-1) infection and whether P. falciparum infection accelerates the progression of HIV-related disease. METHODS We conducted a prospective, longitudinal cohort study in Kinshasa, Zaire. Two hundred sixty children 5 to 9 months of age who had been born to HIV-1-seropositive mothers and 327 children of the same age who had been born to seronegative mothers were monitored intensively for malaria over a 13-month period. All episodes of fever were evaluated with blood smears for malaria, and children found to be infected with P. falciparum were treated with a standard regimen of oral quinine. RESULTS A total of 2899 fevers were evaluated, with 271 cases of malaria identified. No statistically significant differences were found in the incidence, severity, or response to therapy of malaria among four well-defined groups of children: those with the acquired immunodeficiency syndrome (AIDS), those who were HIV-1-seropositive throughout the study, those who were born to HIV-1-seropositive mothers but reverted to seronegative, and those who were seronegative throughout the study. During the 13-month period the incidence of malaria in the 36 children with HIV infection in whom AIDS developed was lower, although not significantly so, than in the 37 in whom AIDS did not. CONCLUSIONS In this study malaria was not more frequent or more severe in children with progressive HIV-1 infection and malaria did not appear to accelerate the rate of progression of HIV-1 disease.


AIDS | 2006

HIV incidence and factors associated with HIV acquisition among injection drug users in St Petersburg, Russia

Andrei P. Kozlov; Alla V. Shaboltas; Olga V. Toussova; Sergei V. Verevochkin; Benoit Masse; Tom Perdue; Geetha Beauchamp; Wayne Sheldon; William C. Miller; Rober Heimer; Robert W. Ryder; Irving Hoffman

Background:The Russian HIV-1 epidemic has been driven by injection drug use. Objective:To determine HIV incidence and identify demographic and behavioral correlates of infection to facilitate the development of longitudinal HIV prevention programs. Methods:In 2002, a cohort of 520 injection drug users (IDU) in St Petersburg, Russia were recruited and tested and counseled for HIV-1. HIV-seronegative IDU were enrolled and reevaluated at 6 and 12 months. HIV testing was performed and sociodemographic and behavioral data were collected during each study visit. The relationship of sociodemographic and behavioral factors to HIV-1 incidence was assessed. Results:Most enrolled subjects were young, male, living at home, educated, heroin users, and frequently shared needles and other injection paraphernalia. The retention rate at the 12 month follow-up was 80%. The HIV-1 incidence rate was 4.5/100 person-years. In univariate analysis, psychostimulant use, especially frequent use, three or more sex partners in the past 6 months, and females selling sex were associated with HIV seroconversion. In the multivariate analysis, psychostimulant use three or more times per week was the only factor still associated with HIV seroconversion. Conclusions:The high incidence of HIV infection places St Petersburg among the worst IDU-concentrated epidemics in Europe. Interventions targeting psychostimulant and heroin users and their accompanying behaviors such as frequent injections and increased sexual activity are needed immediately.


AIDS | 1991

Fertility rates in 238 HIV-1-seropositive women in Zaire followed for 3 years post-partum

Robert W. Ryder; Veronique L. Batter; Malanda Nsuami; Nsanga Badi; Lubaki Mundele; Baangi Matela; Mulenda Utshudi; William L. Heyward

Birth-control use and fertility rates were prospectively determined in 238 HIV-1-seropositive and 315 HIV-1-seronegative women in Kinshasa, Zaire, during the 36-month period following the delivery of their last live-born child. No women delivered children during the first follow-up year. Birth-control utilization rates (percentage use during total observation time) and fertility rates (annual number of live births per 1000 women of child-bearing age) in the second year of follow-up were 19% (107.4 per 1000) for HIV-1-seropositive women and 16% (144.7 per 1000) for HIV-1-seronegative women. In the third year of follow-up these rates were 26 (271.0 per 1000) and 16% (38.6 per 1000) for HIV-1-seropositive and HIV-1-seronegative women, respectively (P less than 0.05 for the difference in birth-control utilization and fertility rates between seropositive and seronegative women in the third year of follow-up). Seven (2.9%) of the 238 HIV-1-seropositive women initially included in the study brought their sex partners in for HIV-1 testing; three (43%) of these men were found to be HIV-1-seropositive. New HIV-1 infection did not have a dramatic effect on the fertility of seropositive women. The nearly uniform unwillingness of HIV-1-seropositive women to inform husbands or sexual partners of their HIV-1 serostatus accounted in large part for the disappointingly high fertility rates in seropositive women who had been provided with a comprehensive program of HIV counseling and birth control. Counseling services for seropositive women of child-bearing age which do not also include these womens sexual partners are unlikely to have an important impact on their high fertility rates.


AIDS | 1993

Impact of HIV counseling and testing among child-bearing women in Kinshasa, Zaïre

William L. Heyward; Veronique L. Batter; Makizayi Malulu; Nkashama Mbuyi; Lubamba Mbu; Michael E. St. Louis; Munkolenkole Kamenga; Robert W. Ryder

Objective:To determine the impact of HIV counseling and testing among child-bearing women. Study setting:Mama Yemo Hospital in Kinshasa, Zaïre. Participants and interventions:After informed consent, 187 HIV-seropositive and 177 HIV-seronegative child-bearing women received pre- and post-test counseling for HIV infection. Main outcome measures:Participant knowledge of HIV/AIDS and plans for notifying partners of serologic status and contraceptive use at the time of counseling, and actual partner involvement and contraception use 12 months later. Results:During pre-test counseling, participant knowledge of HIV infection was high, although 30% of women were unaware of perinatal HIV transmission, and 50% did not know that HIV infection could be asymptomatic. At post-test counseling, 70% of mothers (47% of HIV-seropositive, 94% of HIV-seronegative) intended to notify their partners and have joint counseling and testing, although after 12 months, only 2.2% of all women and 7.9% of those who desired assistance to notify their partner returned with their partners for joint counseling and testing. Similarly, 86% planned to use birth control (61% condoms), with HIV-seropositive women more likely to prefer condoms than HIV-seronegative women (71 versus 53%; P<0.001). After 12-months, however, only 20% of HIV-seropositive women reported condom use, and the frequency of pregnancy in both groups was approximately equal. Conclusions:HIV counseling and testing led to higher rates of contraceptive and condom use, although the actual level was lower than the intended use. To further reduce the risk of heterosexual and perinatal HIV transmission in families with an HIV-infected woman, counseling should also include their male partners. AIDS 1993, 7:1633–1637


Emerging Infectious Diseases | 2007

Endemic Human Monkeypox, Democratic Republic of Congo, 2001–2004

Anne W. Rimoin; Neville K. Kisalu; Benoit Kebela-Ilunga; Thibaut Mukaba; Linda L. Wright; Pierre Formenty; Nathan D. Wolfe; Robert L. Shongo; Florimond Tshioko; Emile Okitolonda; Jean-Jacques Muyembe; Robert W. Ryder; Hermann Meyer

By analyzing vesicle fluids and crusted scabs from 136 persons with suspected monkeypox, we identified 51 cases of monkeypox by PCR, sequenced the hemagglutinin gene, and confirmed 94% of cases by virus culture. PCR demonstrated chickenpox in 61 patients. Coinfection with both viruses was found in 1 additional patient.


The Journal of Infectious Diseases | 2000

The Emergence of Another Tickborne Infection in the 12-Town Area around Lyme, Connecticut: Human Granulocytic Ehrlichiosis

Jacob W. IJdo; James Meek; Matthew L. Cartter; Louis A. Magnarelli; Caiyun Wu; Suzanne W. Tenuta; Erol Fikrig; Robert W. Ryder

Human granulocytic ehrlichiosis (HGE) is an emerging tickborne infection, increasingly recognized in areas in which Lyme disease is endemic, but there are few data on the incidence of HGE. Prospective population-based surveillance was conducted in the 12-town area around Lyme, Connecticut, by means of both active and passive methods, from April through November of 1997, 1998, and 1999. Five hundred thirty-seven residents presenting to their primary care provider with an acute febrile illness suggestive of HGE were identified. Of these, 137 (26%) had laboratory evidence (by indirect fluorescent antibody staining or polymerase chain reaction) of HGE; 89 were confirmed cases, and 48 were probable cases. The incidence of confirmed HGE was 31 cases/100,000 in 1997, 51 cases/100,000 in 1998, and 24 cases/100,000 in 1999. A subset of sera was tested by use of immunoblot assays, and results were in agreement with indirect fluorescent antibody methods for 86% of samples analyzed. Thus, HGE is an important cause of morbidity and is now the second most common tickborne infection in southeastern Connecticut.


AIDS | 1994

AIDS orphans in Kinshasa, Zaïre : incidence and socioeconomic consequences

Robert W. Ryder; Munkolenkole Kamenga; Nkusu M; Batter; William L. Heyward

ObjectiveTo determine the incidence, morbidity, mortality, and socioeconomic consequences of becoming an AIDS orphan (a child with an HIV-1-seropositive mother who has died) in Kinshasa, Zaïre. DesignA longitudinal cohort study was undertaken between 1986 and 1990. Within this cohort, a nested case–control study of AIDS orphans was performed. AIDS orphan cases were children with an HIV-1-seropositive mother who had died. Two groups of control children were identified. The first group of control children were age-matched children with HIV-1-seropositive mothers who were alive at the time of death of the AIDS orphan case mother. The second group of control children were children with HIV-1-seronegative mothers who were also alive at the time of death of the AIDS orphan case mother. SettingObstetric ward and follow-up clinic at two large municipal hospitals in Kinshasa, Zaïre. ParticipantsA total of 466 HIV-1-seropositive women, their children, and the fathers of these children; 606 HIV-1-seronegative women, their children, and the fathers of these children. Main outcome measuresAIDS orphan incidence, HIV-1 vertical transmission rate, morbidity, mortality and socioeconomic indicators of the consequences of becoming an AIDS orphan. ResultsThe AIDS orphan incidence rate was 8.2 per 100 HIV-1-seropositive women-years of follow-up. Vertical transmission of HIV-1 was higher in AIDS orphan cases (41%) than in control children with HIV-1-seropositive mothers (26%; P<0.05). Among children without vertically acquired HIV-1 infection, morbidity rates and indices of social and economic well-being were similar in AIDS orphans and control children. Five out of 26 (19%) AIDS orphan cases died during follow-up, compared with three out of 52 (6%) control children (P<0.05). ConclusionDuring a 3-year follow-up period, children with HIV-1-seropositive mothers had a considerable risk of becoming an AIDS orphan. However, the presence of a concerned extended family appeared to minimize any adverse health and socioeconomic effects experienced by orphan children.


AIDS | 1994

Mortality in HIV-1-seropositive women their spouses and their newly born children during 36 months of follow-up in Kinshasa Zaire.

Robert W. Ryder; Malanda Nsuami; Wato Nsa; Munkolenkole Kamenga; Nsanga Badi; Mulenda Utshudi; William L. Heyward

ObjectiveTo calculate 3-year mortality rates in HIV-1-seropositive and HIV-1-seronegative mothers, their newborn children and the fathers of these children. DesignLongitudinal cohort study of HIV-1-seropositive, age and parity-matched HIV-1-seronegative pregnant women, their newborn babies and the fathers of these children. SettingObstetric ward and follow-up clinic at a large municipal hospital in Kinshasa, Zaïre. ParticipantsA total of 335 newborn children and their 327 HIV-1-seropositive mothers and 341 newborn children and their 337 HIV-1-seronegative mothers and the fathers of these children. Main outcome measuresRates of vertical HIV-1 transmission and maternal, paternal and early childhood mortality. ResultsThe lower and upper bounds of vertical transmission were 27 and 50%, respectively. The 3-year mortality rate was 44% in children with vertically acquired HIV-1 infection, 25% in children with HIV-1-seropositive mothers and indeterminant HIV-1 infection status, and 6% in uninfected children with HIV-1-seronegative mothers. HIV-1-seropositive women who transmitted HIV-1 infection to their most recently born child had lost a greater number of previously born children (mean, 1.5 versus 0.5; P< 0.05), were more likely to have had AIDS at delivery (25 versus 12%; P<0.01) and were more likely to die during follow-up (22 versus 9%; P<0.01) than HIV-1-seropositive women who did not transmit HIV-1 infection to their newborn child. Twenty-five out of 239 (10.4%) fathers of children with HIV-1-seropositive mothers, not lost to follow-up, died compared with three out of 310 (1%) fathers of children with HIV-1-seronegative mothers (P<0.01). ConclusionsFamilies in Kinshasa, Zaïre, in which the mother was HIV-1-sero-positive experienced a five to 10-fold higher maternal, paternal and early childhood mortality rate than families in which the mother was HIV-1 -seronegative.

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William L. Heyward

Centers for Disease Control and Prevention

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Munkolenkole Kamenga

Centers for Disease Control and Prevention

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Marie Laga

Centers for Disease Control and Prevention

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Abib Thiam Manoka

Institute of Tropical Medicine Antwerp

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Nzilambi Nzila

Institute of Tropical Medicine Antwerp

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Anne W. Rimoin

University of California

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Michael E. St. Louis

Centers for Disease Control and Prevention

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