In this research article, we examine why so few of the most promising young scientists in South Africa, those who obtain a P or 'prestigious' rating from the South African National Research Foundation, go on to obtain an A rating, i.e. become leading international scholars in their fields. Drawing on in-depth interviews with 36 P-rated scientists in the period 1983 to 2022, we found that personal characteristics (such as work ethic), the right international networks, and strong departmental support are among the key factors that explain the research accomplishments of highly successful achievers. SIGNIFICANCE: The research is significant for two reasons. It explains why so few promising young scientists in South Africa become world leaders in their respective fields and, in particular, why even fewer young black scientists achieve the highest ratings in their disciplines.

SIGNIFICANCE: Grasslands were often viewed as successional vegetation, a precursor to a possible forest, and were thought to have low diversity. However, a growing number of research projects have shown that these ecosystems boast high biodiversity and massive carbon storing potential, and require at least a century to recover after agricultural ploughing which severely disrupts the environment and consequently lowers plant diversity and carbon stocks. Conserving natural grasslands should be prioritised, as they provide us with important ecosystem services beneficial to not only natural systems, but also the longevity of humans through food security and buffering of the effects of climate change.

BACKGROUND: Respiratory syncytial virus (RSV) is the most common cause of severe bronchiolitis in children worldwide OBJECTIVES: To describe clinical characteristics and outcomes of children hospitalised with bronchiolitis and to compare those with RSV bronchiolitis with children with other viral causes of bronchiolitis METHODS: A retrospective study of children admitted with virally screened bronchiolitis to Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) and Nelson Mandela Children's Hospital (NMCH) from 1 February to 31 August 2018 was conducted, where RSV-positive and -negative children were compared. These children were identified by the National Health Laboratory Service as having undergone respiratory viral multiplex molecular assay analysis and hospital charts were retrospectively reviewed RESULTS: A total of 131 children admitted with bronchiolitis from CMJAH and NMCH were compared in this study, 58 from CMJAH and 73 from NMCH. In the sample group, 65 (49.6%) children had RSV in comparison with 66 (50.4%) children without RSV. Children with RSV comprised 55 (42%) children with RSV only and 10 (7.6%) children with RSV in combination with another respiratory virus. Rhinovirus was the second most common virus detected in this cohort of children (n=17, 12.9%) followed by adenovirus (n=12, 9.2%) and coronavirus (n=9, 6.9%). A statistically significant risk factor noted in children requiring hospitalisation for RSV bronchiolitis was age less than six months (p<0.001 Conclusions. Bronchiolitis is a common disease in children. Respiratory syncytial virus is the most common cause of severe bronchiolitis in hospitalised infants less than six months of age.

Bronchiolitis, a common reason for infant hospitalisation in South Africa (SA), is caused by viral pathogens. Bronchiolitis is typically an illness of mild to moderate severity that occurs in well-nourished children. Hospitalised SA infants frequently have severe disease and/or coexisting medical conditions, and these cases of bronchiolitis may have bacterial co-infection that requires antibiotic therapy. However, the existence of widespread antimicrobial resistance in SA warrants the judicious use of antibiotics. This commentary describes: (i) common clinical pitfalls leading to an incorrect diagnosis of bronchopneumonia; and (ii) considerations for antibiotic therapy in hospitalised infants with bronchiolitis. If antibiotics are prescribed, the indication for their use should be clearly stated, and antibiotic therapy must be stopped promptly if investigations indicate that bacterial co-infection is unlikely. Until more robust data emerge, we recommend a pragmatic management strategy to inform antibiotic use in hospitalised SA infants with bronchiolitis in whom bacterial co-infection is suspected.

Fungal parotitis is rare and the sequela parotid abscess exceedingly so. We report our experience with Candida glabrata and Candida albicans parotid gland abscesses in critically ill HIV-positive patients and highlight the value of microbiological assessment to tailor management.

BACKGROUND: Every Preemie-SCALE developed and piloted the Family-Led Care model, an innovative, locally developed model of care for preterm and low birth weight babies receiving kangaroo mother care. AIM: The aim of this study was to describe healthcare workers' experience using Family-Led Care. SETTING: This study was conducted in five health facilities and their catchment areas in Balaka district, Malawi. METHODS: The mixed-methods design, with two data collection periods, included record reviews, observations and questionnaires for facility staff and qualitative interviews with health workers of these facilities and their catchment areas. The total convenience sample comprised 123 health professionals, support staff and non-professional community health workers. RESULTS: Facility-based staff generally had positive perceptions of Family-Led Care (83%). Knowledge and application-of-knowledge scores were 69% and 52%, respectively. A major change between the first and the second data periods was improvement in client record-keeping. Documentation of newborn vital signs increased from 62% to 92%. Themes emerging from the qualitative interview analysis were the following: benefits of Family-Led Care; activities supporting the implementation of Family-Led Care; own care practices; and families' reaction to and experience of Family-Led Care. CONCLUSION: This article reports improved quality of care through better documentation and better follow-up of preterm and low birth weight babies receiving kangaroo mother care according to the Family-Led Care model. Overall, health workers were positive about their involvement, and they reported positive reactions from families. Lessons learned have been incorporated into a universal Family-Led Care package that is available for adaptation by other countries.

BACKGROUND: As the South African government re-engineers primary healthcare (PHC), the need for additional information on stakeholders involved in the process has emerged. Of these are community health workers (CHWs), who have been identified as central to PHC success. OBJECTIVES: To profile the current CHWs within KwaDabeka and Clermont in KwaZulu-Natal, to describe their roles and to explore the barriers and enablers influencing their service delivery. METHOD: A convergent mixed methods design was employed with a sample of CHWs with the use of a survey (n = 53) and two focus groups (n = 10) and semi-structured interviews with four ward councillors (n = 4). Data were analysed statistically and thematically. RESULTS: The profile of CHWs reflected only women with a mixed age range and a majority of 59% who had not completed formal schooling. General work experience as a CHW varied. There were diverse opinions expressed towards the CHW role which related to their job title and identity, supervision, remuneration, growth pathways and psychological and emotional issues. Whilst the National Community Health Worker Profile Framework was established for the CHW programme, there are several factors lacking in the current CHW programme such as a formal growth pathway or formal training to align the CHWs with the National Qualifications Framework. CONCLUSION: The study findings are essential for the monitoring and evaluation as well as development and refinement of policies that will assist in ensuring adequate rollout of PHC with CHWs.

OBJETIVO: Validar um modelo de obesidade induzida por dieta hiperlipídica, de baixo custo, fácil reprodutibilidade, que mimetizasse características observadas no humano e viabilizasse posteriores proposições terapêuticas. MATERIAIS E MÉTODOS: Dezesseis camundongos Swiss receberam dieta padrão (DP) ou dieta hiperlipídica (DH), durante 10 semanas. RESULTADOS: Embora o grupo DP tenha apresentado maior consumo de água (p < 0,01) e ração (p < 0,001), o grupo DH apresentou maior ganho de peso corpóreo (p < 0,5) e aumento de coxins adiposos (p < 0,001), favorecendo maior índice de adiposidade (p < 0,001), glicemia (p < 0,01) e área sob a curva nos testes de tolerância à insulina (p < 0,001) e à glicose (p < 0,01). CONCLUSÃO: Validou-se um modelo de obesidade induzida por dieta hiperlipídica associada à resistência à ação da insulina e à intolerância à glicose, em um período de 10 semanas.

OBJECTIVE: Validate a model of high-fat diet-induced obesity, of low cost, easy reproducibility, that could express characteristics observed in human, and would enable subsequent therapy proposals. MATERIALS AND METHODS: Sixteen Swiss mice received a standard diet (DP) or high-fat diet (DH) for 10 weeks. RESULTS: Although the DP group had greater water (p < 0.01) and feed (p < 0.001) consumption, the DH group had greater body weight (p < 0.5) and adipose tissue gain (p < 0.001), favoring higher adiposity index (p < 0.001), glucose (p < 0.01), and area under the curve in the insulin (p < 0.001) and glucose (p < 0.01) tolerance tests. CONCLUSION: A high-fat diet-induced obesity model has been validated, which was also associated with insulin resistance and glucose intolerance after a period of 10 weeks.

Objective: To describe the education, research, practice, and policy related to pharmacist interventions to improve medication adherence in community settings in the United States. Methods: Authors used MEDLINE and International Pharmaceutical Abstracts (since 1990) to identify community and ambulatory pharmacy intervention studies which aimed to improve medication adherence. The authors also searched the primary literature using Ovid to identify studies related to the pharmacy teaching of medication adherence. The bibliographies of relevant studies were reviewed in order to identify additional literature. We searched the tables of content of three US pharmacy education journals and reviewed the American Association of Colleges of Pharmacy website for materials on teaching adherence principles. Policies related to medication adherence were identified based on what was commonly known to the authors from professional experience, attendance at professional meetings, and pharmacy journals. Results: Research and Practice: 29 studies were identified: 18 randomized controlled trials; 3 prospective cohort studies; 2 retrospective cohort studies; 5 case-controlled studies; and one other study. There was considerable variability in types of interventions and use of adherence measures. Many of the interventions were completed by pharmacists with advanced clinical backgrounds and not typical of pharmacists in community settings. The positive intervention effects had either decreased or not been sustained after interventions were removed. Although not formally assessed, in general, the average community pharmacy did not routinely assess and/or intervene on medication adherence. Education: National pharmacy education groups support the need for pharmacists to learn and use adherence-related skills. Educational efforts involving adherence have focused on students´ awareness of adherence barriers and communication skills needed to engage patients in behavioral change. Policy: Several changes in pharmacy practice and national legislation have provided pharmacists opportunities to intervene and monitor medication adherence. Some of these changes have involved the use of technologies and provision of specialized services to improve adherence. Conclusions: Researchers and practitioners need to evaluate feasible and sustainable models for pharmacists in community settings to consistently and efficiently help patients better use their medications and improve their health outcomes.

Objetivo: Describir la educación, investigación, practica y política relacionadas con las intervenciones farmacéuticas para mejorar el cumplimiento de la medicación en establecimientos comunitarios en Estados Unidos. Métodos: Los autores utilizaron Medline e International Pharmaceutical Abstracts (desde 1990) para identificar los estudios de intervención de farmacia comunitaria y ambulatoria que trataban de mejorar el cumplimiento de la medicación. Los autores también buscaron en literatura primaria usando Ovid para identificar estudios relativos a la enseñanza de farmacia sobre cumplimiento de la medicación. Se revisaron las bibliografías de los estudios relevantes para identificar literatura adicional. Buscamos en los sumarios de tres revistas de educación de farmacia de Estados Unidos y se revisó la web de la Asociación Americana de Facultades de Farmacia a la busca de materiales sobre principios de educación sobre cumplimiento. Las políticas relacionadas con cumplimiento de medicación se identificaron mediante lo que era conocido por los autores desde su experiencia profesional, asistencia a congresos y revistas farmacéuticas. Resultados: Investigación y práctica: se identificaron 29 estudios: 18 ensayos controlados aleatorizados; 3 estudios de cohorte prospectivos; 2 estudios de cohorte retrospectivos; 5 estudios de caso control; y otro estudio. Hubo una considerable variabilidad en los tipos de intervenciones y en el uso de medidas del cumplimiento. Muchas de las intervenciones eran realizadas por farmacéuticos con formación clínica avanzada y no por típicos farmacéuticos comunitarios. Los efectos positivos de las intervenciones disminuyeron o no se mantuvieron después de que las intervenciones desaparecieron. Aunque no se evaluó formalmente, en general, las farmacias comunitarias normales no evaluaban rutinariamente y/o intervenían en el cumplimiento de la medicación. Educación: Los grupos nacionales de educación de farmacia apoyan la necesidad de que los farmacéuticos aprendan y usen habilidades relacionadas con el cumplimiento. Los esfuerzos educativos relacionados con el cumplimiento se han centrado en el conocimiento de los estudiantes de las barreras al cumplimiento y en las habilidades de comunicación necesarias para envolver a los pacientes en un cambio actitudinal. Política: Varios cambios en el ejercicio de la farmacia y en la legislación nacional han proporcionado a los farmacéuticos la oportunidad de intervenir y monitorizar el cumplimiento de la medicación. Algunos de estos cambios incluyeron el uso de tecnologías y la provisión de servicios especializados para mejorar el cumplimiento. Conclusiones: Los investigadores y facultativos necesitan evaluar modelos factibles y sostenibles para los farmacéuticos en la comunidad para ayudar consistente y eficientemente a pacientes en su mejor uso de las medicaciones y mejorar sus resultados en salud.

The maximum volume of liquid bridge left between two vertically mounted spherical particles has been theoretically determined and experimentally measured. As the gravitational effect has not been neglected in the theoretical model, the liquid interface profile is nonsymmetrical around the X-axis. Symmetry in the interface profile only occurs when either the particle size ratio or the gravitational force becomes zero. In this paper, some equations are derived as a function of the spheres' sizes, gap width, liquid density, surface tension and body force (gravity/centrifugal) to estimate the maximum amount of liquid that can be held between the two solid spheres. Then a comparison is made between the result based on these equations and several experimental results.

PURPOSE: Cardiopulmonary bypass is known to alter propofol pharmacokinetics in patients undergoing cardiac surgery. However, few studies have evaluated the impact of these alterations on postoperative pharmacodynamics. This study was designed to test the hypothesis that changes in propofol pharmacokinetics increase hypnotic effects after cardiopulmonary bypass. METHODS: Twenty patients scheduled for on-pump coronary artery bypass graft (group, n=10) or off-pump coronary artery bypass graft (group, n=10) coronary artery bypass grafts were anesthetized with sufentanil and a propofol target controlled infusion (2.0 µg/mL). Depth of hypnosis was monitored using the bispectral index. Blood samples were collected from the induction of anesthesia up to 12 hours after the end of propofol infusion, at predetermined intervals. Plasma propofol concentrations were measured using high-performance liquid chromatography, followed by a non-compartmental propofol pharmacokinetic analysis. Data were analyzed using ANOVA, considering p<0.05 as significant. RESULTS: After cardiopulmonary bypass, despite similar plasma propofol concentrations in both groups, bispectral index values were lower in the on-pump coronary artery bypass graft group. Time to extubation after the end of propofol infusion was greater in the on-pump coronary artery bypass graft group (334 ± 117 vs. 216 ± 85 min, p = 0.04). Patients undergoing cardiopulmonary bypass had shorter biological (1.82 ± 0.5 vs. 3.67 ± 1.15h, p < 0.01) and terminal elimination (6.27 ± 1.29 vs. 10.5h ± 2.18, p < 0.01) half-life values, as well as higher total plasma clearance (28.36 ± 11.40 vs.18.29 ± 7.67 mL/kg/min, p = 0.03), compared to patients in the off-pump coronary artery bypass graft group. CONCLUSION: Aside from the increased sensitivity of the brain to anesthetics after cardiopulmonary bypass, changes in propofol pharmacokinetics may contribute to its central nervous system effects.

OBJECTIVES: To determine whether contraceptive discontinuation is associated with pregnancies that are conceived earlier than desired (mistimed) or are not wanted at the time of conception (unwanted). METHODS: Data were obtained from the 2002 Guatemala National Maternal and Child Health Survey. Pregnancies within the three years prior to and at the time of the survey (April 1999-November 2002) were classified as either "intended," "mistimed," or "unwanted." The key independent variable was whether the woman had used contraception within 12 months of the pregnancy and, for those who had used it, the reason for discontinuation (either to get pregnant or for another reason). A multinomial logistic analysis was used to determine the degree of association of discontinuation with pregnancy intentions. RESULTS: One of every five mistimed pregnancies and one of every six unwanted pregnancies followed discontinuations that were for reasons other than to become pregnant (e.g., contraceptive failure, side effects, and health concerns). Discontinuations for reasons other than to become pregnant were shown to be positively and significantly associated with a reported mistimed pregnancy (coefficient = 2.15; standard error = 0.27) or unwanted pregnancy (2.68; 0.37) compared to an intended pregnancy. Pregnancies preceded by discontinuations for reasons other than to become pregnant were also more likely to be reported as mistimed or unwanted than pregnancies of women who were not using contraception during the year prior to pregnancy. CONCLUSIONS: There is a need to increase contraceptive continuation. Any program should include an increased effort to reduce contraceptive failure and better address the side effects and the health concerns that women have that can lead to discontinuation. Non-users who want to delay or limit births should also be identified and targeted for outreach in order to reduce unintended pregnancies.

OBJETIVOS: Determinar si la suspensión del uso de anticonceptivos (SUA) está asociada con embarazos concebidos antes de lo deseado (inoportunos) o no deseados. MÉTODOS: Se usaron los datos de la Encuesta Nacional de Salud Materna e Infantil en Guatemala de 2002. Los embarazos registrados entre los tres años previos a la encuesta (desde abril de 1999) y el final de la misma (noviembre de 2002) se clasificaron como deseados, inoportunos o no deseados. La variable independiente principal fue si la mujer había usado algún anticonceptivo en los 12 meses previos al embarazo y, en ese caso, la razón de la SUA (para lograr un embarazo u otra razón). Mediante el análisis logístico polinominal se determinó el grado de asociación entre la SUA y el tipo de embarazo resultante. RESULTADOS: Uno de cada cinco embarazos inoportunos y uno de cada seis embarazos no deseados sucedieron a la SUA por razones ajenas al deseo de un embarazo (por ejemplo, fallas o efectos secundarios del anticonceptivo, o consideraciones de salud). Se encontró una asociación directa y significativa entre la SUA por razones ajenas al deseo de quedar embarazada y los embarazos clasificados como inoportunos (coeficiente = 2,15; error estándar = 0,27) o no deseados (2,68; 0,37), en contraste con los embarazos deseados. Las mujeres que suspendieron el uso de anticonceptivos por razones ajenas al deseo de un embarazo presentaron una mayor probabilidad de considerar sus embarazos inoportunos o no deseados que las mujeres que no emplearon medios anticonceptivos en el año previo a su embarazo. CONCLUSIONES: Es necesario promover el uso continuado de los anticonceptivos. Los programas deben hacer un mayor esfuerzo para reducir las fallas de los anticonceptivos, informar mejor sobre los efectos secundarios y aclarar las preocupaciones sanitarias que puedan llevar a la SUE. A fin de reducir el número de embarazos no programados, se deben identificar y captar a las mujeres que no usan anticonceptivos y quieren demorar o evitar un embarazo.

The fossil-rich deposits of Térapa (east-central Sonora) contain more than 60 zoological taxa, many with tropical affinities such as Crocodylus (crocodylian), Hydrochaeris (capybara), and many birds. The deposits also contain the dermal ossicles (osteoderms) of two extinct xenarthrans, a glyptodont (Glyptotherium cylindricum) and a pampathere (giant armadillo; Pampatherium cf. mexicanum). Glyptodont remains are also known from other less-well studied localities in Sonora. The faunas from these localities also contain the genus Bison, which indicates that the deposits are of the Rancholabrean Land Mammal Age, late Pleistocene. The presence of Pampatherium at Térapa and the presence of Glyptotherium at Térapa and the Río Mayo/Río Yaqui sites represent the first published accounts of these species from Sonora, and greatly extends their known geographical distribution during the Rancholabrean by about 1,100 km into northwestern Mexico.

Los yacimientos ricos en fósiles de Térapa (área centro-oriental de Sonora) contienen más de 60 taxon zoológicas, muchos con afinidades tropicales como Crocodylus (crocodrilo), Hydrochaeris (capibara), y muchas aves. Los depósitos contienen además la dermis ósea de oído (osteodermis) de dos xenartros extintos, un gliptodonte (Glyptotherium cylindricum) y un armadillo gigante (Pampatherium cf. mexicanum) (Mammalia, Xenarthra). También se han hallado restos de gliptodonte en otras localidades de Sonora menos estudiadas. Las faunas de estas localidades contienen además el género Bison, lo cual indica que los depósitos son del Rancholabreano (Rancholabrean Land Mammal Age), Pleistoceno tardío. La presencia de Pampatherium en Térapa y de Glyptotherium en Térapa y los sitios del Río Mayo/Río Yaqui representa el primer recuento publicado de estas especies en Sonora y extiende grandemente su distribución conocida durante el Rancholabreano, o pleistoceno tardío, en unos 1,100 kms hacia el noroeste de México.

OBJECTIVE: To estimate the prevalence of the hepatitis C virus (HCV) and HIV infection and associated risk behaviors among injection drug users (IDUs) in two northern Mexican cities. MATERIAL AND METHODS: Between February and April 2005, IDUs were recruited in Tijuana (N=222) and Ciudad Juarez (N=206) using respondent-driven sampling (RDS), a chain referral sampling approach. Interviewer-administered questionnaires assessed drug-using behaviors during the prior six months. Venous blood was collected for immunoassays to detect HIV and HCV antibodies. For HIV, Western blot or immunofluorescence assay was used for confirmatory testing. Final HCV antibody prevalence was estimated using RDS adjustments. RESULTS: Overall, HCV and HIV prevalence was 96.0% and 2.8%, respectively, and was similar in both cities. Most IDUs (87.5%) reported passing on their used injection equipment to others, and 85.9% had received used equipment from others. CONCLUSIONS: HIV prevalence was relatively high given the prevalence of HIV in the general population, and HCV prevalence was extremely high among IDUs in Tijuana and Ciudad Juarez. Frequent sharing practices indicate a high potential for continued transmission for both infections. HCV counseling and testing for IDUs in Mexico and interventions to reduce sharing of injection equipment are needed.

OBJETIVO: Estimar las prevalencias de los virus de hepatitis C (VHC) y de VIH y los comportamientos de riesgo asociados con ellos, entre usuarios de drogas inyectables (UDI) en dos ciudades del norte de México. MATERIAL Y MÉTODOS: Entre febrero y abril de 2005, se reclutaron UDIs en Tijuana (N=222) y en Ciudad Juárez (N=206), mediante un método de muestreo llamado en inglés "respondent-driven sampling" (RDS), lo cual es un sistema basado en cadenas de referencia. Los participantes contestaron una encuesta aplicada por entrevista, la cual indagó acerca de los comportamientos en el uso de drogas durante los seis meses previos. Una muestra de sangre venosa fue colectada de cada individuo, para determinar la presencia de anticuerpos contra VIH y VHC mediante técnicas inmunoenzimáticas. En el caso del VIH la técnica de "Western blot" se aplicó con fines de confirmación. La prevalencia final de anticuerpos contra VHC se hizo mediante un cálculo ajustado, que empleó un estimador poblacional del RDS. RESULTADOS: Las seroprevalencias globales de VHC y VIH, fueron 96% y 2.8%, respectivamente. Estas frecuencias fueron similares entre las muestras de ambas ciudades. La gran mayoría de los UDI (87.5%) manifestó haber transferido a otros sus equipos de inyección usados y a su vez 85.9% de los participantes declaró haber recibido equipos usados de otros. CONCLUSIONES: La seroprevalencia encontrada de VIH fue relativamente alta dada la prevalencia de VIH en la población general y la de VHC fue extremadamente alta entre los UDI estudiados en Tijuana y en Ciudad Juárez. Las prácticas frecuentes de compartimiento de equipo señalan hacia un alto potencial que favorece la transmisión de ambas infecciones investigadas. Por tanto, son necesarias actividades de consejería y pruebas de laboratorio para VHC dirigidas a UDI en México y asimismo intervenciones para reducir el uso compartido de equipos de inyección.

OBJECTIVE: To estimate the prevalence of the hepatitis C virus (HCV) and HIV infection and associated risk behaviors among injection drug users (IDUs) in two northern Mexican cities. MATERIAL AND METHODS: Between February and April 2005, IDUs were recruited in Tijuana (N=222) and Ciudad Juarez (N=206) using respondent-driven sampling (RDS), a chain referral sampling approach. Interviewer-administered questionnaires assessed drug-using behaviors during the prior six months. Venous blood was collected for immunoassays to detect HIV and HCV antibodies. For HIV, Western blot or immunofluorescence assay was used for confirmatory testing. Final HCV antibody prevalence was estimated using RDS adjustments. RESULTS: Overall, HCV and HIV prevalence was 96.0% and 2.8%, respectively, and was similar in both cities. Most IDUs (87.5%) reported passing on their used injection equipment to others, and 85.9% had received used equipment from others. CONCLUSIONS: HIV prevalence was relatively high given the prevalence of HIV in the general population, and HCV prevalence was extremely high among IDUs in Tijuana and Ciudad Juarez. Frequent sharing practices indicate a high potential for continued transmission for both infections. HCV counseling and testing for IDUs in Mexico and interventions to reduce sharing of injection equipment are needed.

OBJETIVO: Estimar las prevalencias de los virus de hepatitis C (VHC) y de VIH y los comportamientos de riesgo asociados con ellos, entre usuarios de drogas inyectables (UDI) en dos ciudades del norte de México. MATERIAL Y MÉTODOS: Entre febrero y abril de 2005, se reclutaron UDIs en Tijuana (N=222) y en Ciudad Juárez (N=206), mediante un método de muestreo llamado en inglés "respondent-driven sampling" (RDS), lo cual es un sistema basado en cadenas de referencia. Los participantes contestaron una encuesta aplicada por entrevista, la cual indagó acerca de los comportamientos en el uso de drogas durante los seis meses previos. Una muestra de sangre venosa fue colectada de cada individuo, para determinar la presencia de anticuerpos contra VIH y VHC mediante técnicas inmunoenzimáticas. En el caso del VIH la técnica de "Western blot" se aplicó con fines de confirmación. La prevalencia final de anticuerpos contra VHC se hizo mediante un cálculo ajustado, que empleó un estimador poblacional del RDS. RESULTADOS: Las seroprevalencias globales de VHC y VIH, fueron 96% y 2.8%, respectivamente. Estas frecuencias fueron similares entre las muestras de ambas ciudades. La gran mayoría de los UDI (87.5%) manifestó haber transferido a otros sus equipos de inyección usados y a su vez 85.9% de los participantes declaró haber recibido equipos usados de otros. CONCLUSIONES: La seroprevalencia encontrada de VIH fue relativamente alta dada la prevalencia de VIH en la población general y la de VHC fue extremadamente alta entre los UDI estudiados en Tijuana y en Ciudad Juárez. Las prácticas frecuentes de compartimiento de equipo señalan hacia un alto potencial que favorece la transmisión de ambas infecciones investigadas. Por tanto, son necesarias actividades de consejería y pruebas de laboratorio para VHC dirigidas a UDI en México y asimismo intervenciones para reducir el uso compartido de equipos de inyección.