A multifaceted intervention to prevent American cutaneous leishmaniasis in Colombia: results of a group-randomized trial / Prevención de leishmaniasis cutánea americana en Colombia mediante una intervención múltiple: resultados de un ensayo de grupos aleatorios

Introducción. La leishmaniasis cutánea americana es endémica en Colombia, donde cada año son notificados aproximadamente 6000 casos nuevos. En la actualidad las medidas de prevención y control están limitadas al diagnóstico y tratamiento de los casos. Objetivo. Evaluar la eficacia de una intervención múltiple para prevenir la transmisión de Leishmania en el foco endémico de Tumaco, costa Pacífica de Colombia. Materiales y métodos. Se realizó un ensayo de grupos aleatorizados. Veinte veredas fueron pareadas según prevalencia de Leishmania, habitantes y participación comunitaria y luego asignadas aleatoriamente a intervención o control. La intervención incluyó toldillos impregnados con deltametrina, repelente (N, N-dietil-m-toluamida 20 por ciento y Permetrina 0,5 por ciento), modificación de lugares de reposo para los vectores y educación. Al cabo de un año se comparó la incidencia de infección y enfermedad producida por Leishmania en los dos grupos, se monitorearon la adherencia a la intervención y la aparición de efectos adversos. Los resultados finales fueron ajustados por el efecto de correlación intra-grupo. Resultados. Se presentaron 10 casos de leishmaniasis cutánea americana en el grupo que recibió la intervención y 23 en el grupo control, OR=0,42, IC95 por ciento 0,14-1,26. La intervención tuvo un mayor efecto en los niños menores de 10 años, en aquellos que residían en la periferia de la vereda y en veredas con una prevalencia de infección en niños pequeños mayor del 1 por ciento. Se reportaron eventos adversos leves asociados con el uso de los toldillos impregnados y el repelente en 2 por ciento de los participantes. Conclusión. Los casos nuevos de Leishmaniasis cutánea americana se redujeron en un 58 por ciento en el grupo que recibió la intervención. Sin embargo, el número pequeño de casos hace que la estimación de la medida de efecto sea imprecisa y no nos permite afirmar que la intervención tiene un efecto protector. Poblaciones específicas podr...

Introduction. American cutaneous leishmaniasis is endemic in Colombia, where approximately 6.000 new cases are reported every year. Current prevention and control measures are restricted to the diagnosis and treatment of cases. Objective. To evaluate the efficacy of a multifaceted intervention to prevent the transmission of Leishmania in the endemic focus of Tumaco, on the Pacific Coast of Colombia. Materials and methods. A group-randomized trial was conducted. Twenty villages were matched according to prevalence of Leishmania infection, number of inhabitants and level of community participation, and then randomly assigned to intervention or control. The intervention included deltamethrin-impregnated bednets, repellent (20% diethyltoluamide and 0.5% permethrin), modification of sand fly resting sites, and health education. Villages were under surveillance for one year and the use of the intervention measures monitored. The incidence of American cutaneous leishmaniasis and Leishmania infection in the two groups were compared, adherence to the intervention and adverse events were monitored, and the results were adjusted for village intraclass correlation. Results. Ten cases of American cutaneous leishmaniasis were confirmed in the intervention and 23 in the control group, OR = 0.42, 95% CI 0.14-1.26. The intervention had a greater effect in children < 10 years old, in people living on the periphery of the village and in villages with a prevalence of infection in small children > 1%. Adverse events associated with the use of the bednets and the repellent were reported in 2% of the participants and were always mild. Conclusion. Incident cases of American cutaneous leishmaniasis were reduced by 58% in the intervention group. However, the small number of cases renders the effect estimate imprecise and precludes us to claim a protective effect for the intervention. Specific populations could be the targets of simpler and more cost-effective interventions in the future.

A multifaceted intervention to prevent American cutaneous leishmaniasis in Colombia: results of a group-randomized trial.

INTRODUCTION: American cutaneous leishmaniasis is endemic in Colombia, where approximately 6.000 new cases are reported every year. Current prevention and control measures are restricted to the diagnosis and treatment of cases. OBJECTIVE: To evaluate the efficacy of a multifaceted intervention to prevent the transmission of Leishmania in the endemic focus of Tumaco, on the Pacific Coast of Colombia. MATERIALS AND METHODS: A group-randomized trial was conducted. Twenty villages were matched according to prevalence of Leishmania infection, number of inhabitants and level of community participation, and then randomly assigned to intervention or control. The intervention included deltamethrin-impregnated bednets, repellent (20% diethyltoluamide and 0.5% permethrin), modification of sand fly resting sites, and health education. Villages were under surveillance for one year and the use of the intervention measures monitored. The incidence of American cutaneous leishmaniasis and Leishmania infection in the two groups were compared, adherence to the intervention and adverse events were monitored, and the results were adjusted for village intraclass correlation. RESULTS: Ten cases of American cutaneous leishmaniasis were confirmed in the intervention and 23 in the control group, OR = 0.42, 95% CI 0.14-1.26. The intervention had a greater effect in children < 10 years old, in people living on the periphery of the village and in villages with a prevalence of infection in small children > 1%. Adverse events associated with the use of the bednets and the repellent were reported in 2% of the participants and were always mild. CONCLUSION: Incident cases of American cutaneous leishmaniasis were reduced by 58% in the intervention group. However, the small number of cases renders the effect estimate imprecise and precludes us to claim a protective effect for the intervention. Specific populations could be the targets of simpler and more cost-effective interventions in the future.

Racial and ethnic disparities in influenza vaccination among elderly adults.

OBJECTIVES: To examine whether access to care factors account for racial/ethnic disparities in influenza vaccination among elderly adults in the United States. DESIGN: Indicators of access to care (predisposing, enabling, environmental/system, and health need) derived from Andersen's behavioral model were identified in the National Health Interview Survey questionnaire. The relationship of these indicators to influenza vaccination and race/ethnicity was assessed with multiple logistic regression models. MAIN RESULTS: Significant differences in vaccination were observed between non-Hispanic (NH) whites (66%) and Hispanics (50%, P<.001) and between NH whites (66%) and NH blacks (46%, P<.001). Controlling for predisposing and enabling access to care indicators, education, marital status, regular source of care, and number of doctor visits, reduced the prevalence odds ratios (POR) comparing Hispanics to non-Hispanic whites from 1.89 to 1.27. For NH blacks, controlling for access to care indicators changed the POR only from 2.24 (95% CI, 1.9 to 2.7) to 1.93 (95% CI, 1.6 to 2.4). CONCLUSIONS: This study confirmed the existence of sizable racial/ethnic differences in influenza vaccination among elderly adults. These disparities were only partially explained by differences in indicators of access to care, especially among non-Hispanic blacks for whom large disparities remained. Factors not available in the National Health Interview Survey, such as patient attitudes and provider performance, should be investigated as possible explanations for the racial/ethnic disparity in influenza vaccination among non-Hispanic blacks.

Assessment by meta-analysis of PCR for diagnosis of smear-negative pulmonary tuberculosis.

We conducted a meta-analysis to assess the performance of PCR for the diagnosis of smear-negative pulmonary tuberculosis (SPT) and to identify factors that account for differences in the diagnostic accuracy of different studies. Studies published before February 2002 were included if sensitivity and specificity of PCR in smear-negative respiratory or gastric-aspirate specimens could be calculated. Analysis was conducted by using summary receiver operating characteristics models. Sensitivity and specificity ranged from 9 to 100% and from 25 to 100%, respectively. Fewer than 40% of the 50 studies reported results by number of patients, reported clinical characteristics of patients, or used as a reference standard combined culture and clinical criteria. Studies that included bronchial specimens showed higher accuracy than studies that evaluated only sputum specimens or included gastric aspirates. Studies that did not report that tests were applied blindly showed higher accuracy than those reporting blind testing. Increased sensitivity due to the use of DNA purification methods was associated with decreased specificity. Studies published after 1995, using Amplicor or dUTP-UNG, were associated with an increase in specificity at the expense of lower sensitivity. We concluded that PCR is not consistently accurate enough to be routinely recommended for the diagnosis of SPT. However, PCR of bronchial specimens could be useful in highly suspicious SPT cases. Studies not reporting blind testing are likely to overestimate accuracy of PCR. Future evaluation of PCR accuracy should be conducted by patient and type of respiratory specimen, blindly, by using a reference standard that combines culture and clinical criteria and addresses the issue of how patient characteristics affect PCR accuracy.

Surveillance and screening of American cutaneous leishmaniasis by Colombian primary health care workers using a clinical prediction rule.

Confirmed cases of American cutaneous leishmaniasis (ACL) and other dermatological diseases were evaluated in Colombia with a clinical prediction rule independently by 3 types of evaluators: community health volunteer (CHV), practical nurse (PN) and programme physician (PP). The adapted prediction rule included 6 variables based upon clinical-historical information. The screening instrument was a rotating tower of coloured squares, one colour for each variable. A score ranging from 0 to 7, and a cutoff point of > or = 4 was selected for ACL classification (sensitivity 94.3%, specificity 53.3% and efficiency 80.3%). Disease classification, total score, and variable-specific score obtained by CHVs and PNs were compared to those obtained by a PP. The impact on case detection in the study area was assessed. Both types of primary health worker had a high agreement with the PP (sensitivity) on the classification of patients with ACL by score, CHV (92.3%) and PN (93.3%). Case detection of ACL increased 3-fold over that observed one year earlier. This screening instrument and prediction rule, when incorporated into a community surveillance programme for ACL, can facilitate greater case detection and appropriate referral for more-specific diagnostic procedures.

Heterogeneity, geographic distribution, and pathogenicity of serodemes of Leishmania viannia in Colombia.

Leishmania Viannia strains from 1,092 patients who acquired dermal leishmaniasis in endemic regions of Colombia were analyzed for expression of species and subgenus specific epitopes. Eight monoclonal antibodies prepared against membranes of the major species of the Viannia subgenus and previously shown to distinguish these species, recognized low molecular mass (< 45kD) membrane components. Thirteen widely but non-uniformly distributed serodemes were identified: one unique to L. panamensis, four unique to L. braziliensis and eight that were common to L. braziliensis and L. guyanensis. Thirty-seven percent of Colombian L. braziliensis strains concomitantly typed by isoenzymes were null, i.e., not recognized by the corresponding species-specific B-16 or B-18 antibodies. No Colombian L. guyanensis strains were recognized by the antibody specific for this species (B-19). In contrast, L. panamensis-specific B-4 and B11 antibodies recognized > 98% of the L. panamensis strains. Null strains of L. braziliensis and L. panamensis were more frequently isolated from mucosal leishmaniasis than strains that expressed species specific epitopes, suggesting that these strains may be more pathogenic.

PCR-based diagnosis of acute and chronic cutaneous leishmaniasis caused by Leishmania (Viannia).

We evaluated PCR methods for diagnosis of acute and chronic cutaneous leishmaniasis (CL) in an area of Colombia where Leishmania (Viannia) is endemic. The PCR method specifically amplified whole linearized minicircle kinetoplast DNA (kDNA) of the Leishmania subgenus Viannia from biopsy lysates. PCR products were detected in agarose gels. For 255 acute cases, this PCR method had greater sensitivity (75.7%) than each conventional method, i.e., microscopic examination of Giemsa-stained lesion scraping (46.7%), biopsy culture (55.3%), aspirate culture (46.3%), and the conventional methods combined (70.2%). Among 44 cases of chronic CL, amplification of biopsy DNA was more sensitive (45.5%) than the individual (4.5 to 27.7%) and combined (27.3%) conventional methods. The detection of kDNA in biopsies from chronic lesions was enhanced by a chemiluminescent dot blot hybridization, which produced a sensitivity of 65.8% when alone and 90.9% when in combination with DNA extraction of biopsy lysates (P < 0.001). Three biopsies from 84 skin lesions of other etiologies were falsely positive by PCR (specificity, 96.4%). PCR detected kDNA more frequently in biopsies (detection level, 83.9%) than in aspirates (74.7%) from 103 cases of acute CL. Among aspirates from 53 chronic cases of CL, the alternative methods, DNA extraction and hybridization, increased sensitivity from 41.5 to 56.6% (P > 0.05). This enhanced PCR method in chronic biopsies was so much more sensitive than conventional methods that it should be considered the preferred diagnostic method for chronic CL. These findings support the appropriate incorporation of PCR into diagnostic strategies for cutaneous leishmaniasis.

Evaluación de la respuesta de isotipos de inmunoglobulina especifica a Leishmania en leishmaniasis tegumentaria Americana / Evaluation of immunoglobin isotype specific to Leishmania in tegumentary American leishmaniasis

Con el fin de determinar las clases de anticuerpo producido contra el parásito y la cinética de los mismos en relación a la evolución de la infección, se estudiaron los sueros de 133 pacientes infectados con Leishmania del complejo braziliensis. Se utilizó la prueba de inmunofluorescencia indirecta y amastigotas de L. mexicana amazonensis como antígeno. En los sueros obtenidos al momento de consultar para el diagnóstico se encontró IgM en 54 de los sueros absorbidos con Straphylococcus aureus Cowan I y en 5 de los no absorbidos. La IgM sólo se encontro en los sueros de pacientes con tiempo devolución de las lesiones < ou = de 2 meses. la IgG se detectó en todos los sueros no absorbidos. Los sueros tomados durante recurrencia y después de cicatrización sólo presentaron IgG. El uso combinado de la prueba de Montenegro y/o título de IgM específico, aumentó el porcentage de pacientes con un diagnóstico inmunológico positivo en aquéllos cuyas lesiones tenían un tiempo de evolución menor de 2 meses. En los sueros de los 10 individuos sanos no se detectó inmunoglobulina específica a Leishmania y ninguno presentó reacción positiva a la prueba de Montenegro. Entre los 16 pacientes con otra etiología, 3 con esporotricosis, mostraron en su suero IgG reactiva con Leishmania pero ninguno incluyendo 2 con menos de dos meses de evolución de las lesiones presentó IgM. concluimos que en pacientes infectados con L. braziliensis la presencia de IgM e IgG específica a Leishmania esta asociado con el tiempo de evolución de las lesiones y el estado primario recurrente de la infección; demás la detección de IgM anti-Leishmania combinada con la respuesta de Mn sería de potencial utilidad en el diagnóstico clínico de la leishmaniasis tegumentaria temprana