SARS-Cov-2: The Relevance and Prevention of Aerosol Transmission.

Coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), has claimed many victims worldwide due to its high virulence and contagiousness. The person-to-person transmission of SARS-Cov-2 when in close contact is facilitated by respiratory droplets containing the virus particles, and by skin contact with contaminated surfaces. However, the large number of COVID-19 infections cannot be explained only by droplet deposition or contact contamination. It seems very plausible that aerosols are important in transmitting SARS-Cov-2. It has been demonstrated that SARS-CoV-2 remains viable in aerosols for hours, facilitating rapid distribution of the virus over great distances. Aerosols may, therefore, also be responsible for so-called super-spreader events. Indirect evidence points to a correlation between ventilation and the transmission and spread of SARS-Cov-2, supporting ventilation as an important factor in preventing airborne transmission. Further actions to avoid transmission of COVID-19 include social distancing, hygiene measures, and barrier measures, such as face-coverings. Professional masks offer better protection than cloth masks. These protection measures are especially relevant to health care workers, when performing endotracheal intubation, but the risk from non-invasive ventilation and nebulizing treatment seems to be moderate.

Improving Methods to Classify Perinatal versus Nonperinatal HIV Acquisition in Young Adolescents 10-14 Years of Age.

Mode of HIV acquisition for adolescents with HIV is often not recorded within routine healthcare databases. Hence, age at enrollment in HIV care is often used as a proxy for perinatal versus nonperinatal infection. Using routine cohort data from adolescents presenting for HIV care 10-14 years of age, we developed logistic regression models to predict likely mode of infection.

Evaluation of the number of undiagnosed infected in an outbreak using source of infection measurements.

In times of outbreaks, an essential requirement for better monitoring is the evaluation of the number of undiagnosed infected individuals. An accurate estimate of this fraction is crucial for the assessment of the situation and the establishment of protective measures. In most current studies using epidemics models, the total number of infected is either approximated by the number of diagnosed individuals or is dependent on the model parameters and assumptions, which are often debated. We here study the relationship between the fraction of diagnosed infected out of all infected, and the fraction of infected with known contaminator out of all diagnosed infected. We show that those two are approximately the same in exponential models and across most models currently used in the study of epidemics, independently of the model parameters. As an application, we compute an estimate of the effective number of infected by the SARS-CoV-2 virus in various countries.

Identifying airborne transmission as the dominant route for the spread of COVID-19.

Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.

The COVID-19 epidemic, its mortality, and the role of non-pharmaceutical interventions.

COVID-19 has developed into a pandemic, hitting hard on our communities. As the pandemic continues to bring health and economic hardship, keeping mortality as low as possible will be the highest priority for individuals; hence governments must put in place measures to ameliorate the inevitable economic downturn. The course of an epidemic may be defined by a series of key factors. In the early stages of a new infectious disease outbreak, it is crucial to understand the transmission dynamics of the infection. The basic reproduction number (R0), which defines the mean number of secondary cases generated by one primary case when the population is largely susceptible to infection ('totally naïve'), determines the overall number of people who are likely to be infected, or, more precisely, the area under the epidemic curve. Estimation of changes in transmission over time can provide insights into the epidemiological situation and identify whether outbreak control measures are having a measurable effect. For R0 > 1, the number infected tends to increase, and for R0 < 1, transmission dies out. Non-pharmaceutical strategies to handle the epidemic are sketched and based on current knowledge, the current situation is sketched and scenarios for the near future discussed.

Infectious Disease Dynamics Inferred from Genetic Data via Sequential Monte Carlo.

Genetic sequences from pathogens can provide information about infectious disease dynamics that may supplement or replace information from other epidemiological observations. Most currently available methods first estimate phylogenetic trees from sequence data, then estimate a transmission model conditional on these phylogenies. Outside limited classes of models, existing methods are unable to enforce logical consistency between the model of transmission and that underlying the phylogenetic reconstruction. Such conflicts in assumptions can lead to bias in the resulting inferences. Here, we develop a general, statistically efficient, plug-and-play method to jointly estimate both disease transmission and phylogeny using genetic data and, if desired, other epidemiological observations. This method explicitly connects the model of transmission and the model of phylogeny so as to avoid the aforementioned inconsistency. We demonstrate the feasibility of our approach through simulation and apply it to estimate stage-specific infectiousness in a subepidemic of human immunodeficiency virus in Detroit, Michigan. In a supplement, we prove that our approach is a valid sequential Monte Carlo algorithm. While we focus on how these methods may be applied to population-level models of infectious disease, their scope is more general. These methods may be applied in other biological systems where one seeks to infer population dynamics from genetic sequences, and they may also find application for evolutionary models with phenotypic rather than genotypic data.

Raiva bovina segundo os mosaicos de uso e cobertura da terra no estado de São Paulo entre 1992 e 2003 / Cattle rabies according to the mosaics of land use and land cover in the state of Sao Paulo from 1992 to 2003

O objetivo deste trabalho foi descrever a influência dos mosaicos de uso e de cobertura da terra na distribuição espacial da raiva bovina na região de maior incidência do Estado de São Paulo, entre 1992 e 2003. Geotecnologias foram utilizadas para gerar três camadas sobrepostas: a enfermidade caracterizada por uma função kernel, os tipos de uso e classes de cobertura da terra obtidos por classificação de imagens de satélites e a altitude. A enfermidade esteve fortemente moldada pelas áreas de vegetação rasteira (pastagens). O relevo pareceu formar os mosaicos de uso e cobertura da terra, os quais acabaram determinando os locais de grassamento ou não da enfermidade. Grandes áreas contínuas do mesmo tipo de uso e classe de cobertura da terra tenderam a ser protetoras da raiva bovina, ou favorecedoras em áreas vizinhas.

The influence of the mosaics of land use and land cover in the spatial distribution of cattle rabies was described in the major incidence region of the State of Sao Paulo, from 1992 to 2003. Geotechnologies were used to build three layers: the disease established by a kernel function, the land use and land cover obtained by satellite images classification, and the altitude. The disease was hardly shaped by grasslands. The relief seems to form the land use and land cover, which determine the regions for the occurrence or not of the disease. Large continuous areas of the same land use and land cover tend to be a protection to cattle rabies or to favor it in the neighborhood areas.

Pautas para el diagnóstico, notificación y asesoramiento de la infección por virus linfotrópico T humano tipo 1 y 2 (HTLV-1/2) en Argentina / Guidelines for the diagnosis, notification and advising for human T-cell lymphotropic virus type 1 and 2 infection in Argentina

El virus linfotrópico T-humano tipo 1 (HTLV-1), primer oncoretrovirus humano descubierto, es el agente etiológico de la Leucemia de Células T del Adulto (ATL) y de la Mielopatía Asociada al HTLV-1 o Paraparesia Espástica Tropical (HAM/TSP). El HTLV-2, no tiene un rol etiológico definido, si bien se lo ha asociado con síndromes neurológicos similares a la HAM/TSP. En Argentina, la detección de anticuerpos para HTLV-1/2 en donantes de sangre es obligatoria desde noviembre de 2005 (resolución 865/2006 del Ministerio de Salud y Ambiente), si bien fue recomendada por la Asociación Argentina de Hemoterapia e Inmunohematología desde el año 1997. Uno de los problemas que se presenta en nuestro país, es la notificación de resultados de esta infección y las dificultades que debe afrontar el médico para brindar la información correcta. En este trabajo se presenta una visión general sobre estos retrovirus, y en especial se brinda información sobre diagnóstico, patogenia y las conductas a seguir por los profesionales de la salud ante la necesi­dad de informar resultados basados únicamente en pruebas de tamizaje o con serología positiva para HTLV­1/2. Para el mismo, nos hemos basado en las recomendaciones y lineamientos elaborados por los Centros de Control de Enfermedades (CDC) y Prevención y el grupo de trabajo del Servicio de Salud Pública de Estados Unidos (USPHS Working Group) dirigidas a las personas infectadas y a trabajadores de la salud e instituciones oficiales de salud pública.

Human T-celllymphotropic virus type 1 (HTLV-1), the first human oncoretrovirus discovered, is the ethiologic agent of Adult T-cell Leukimia (ATL) and HTLV-1 Associated Mielopathy o Tropical Spastic Paraparesis (HAM/TSP). HTLV-2, has not a defined ethiopathology, although it has been associated to neurologic syndroms similar to HAM/TSP Screening for HTLV-1/2 antibodies in blood donors is mandatory since 2005 (Resolution 865/2006 of the Ministry of Health, Argentina) although it has been recomended by the Hemotherapy and Immunehemathology Association since 1997. One of the problems in our country is the notification of the results and the difficulties encountered by the medical doctor in order to provide the appropriate information. In this study, we provide an outlook of these retroviruses, and especially we give information about diagnosis, pathogenesis and guidelines for health professionals when HTLV-1/2 positive serology needs to be notified. We based these recommendations on the guidelines elaborated by the Centers for Disease Control and Prevention and the working group of the US Public Health Service (USPHS Working Group) directed to infected people and to health workers and official institutions of public health.

[Transmission of Mycobacterium tuberculosis among household contacts of patients with tuberculosis]. / Badanie transmisji Mycobacterium tuberculosis wsród osób blisko spokrewnionych chorych na gruzlice.

OBJECTIVE: The aim of this study was estimation of usefulness of two molecular methods for Mycobacterium tuberculosis typing in the epidemiological research of tuberculosis (TB). We determined molecular patterns of M. tuberculosis strains isolated from 66 patients, members of 29 families living in 9 voivodeships of Poland. We also analysed drug susceptibility of the strains as well as some demographic characteristics of the patients. METHODS: The genotype analysis of the 66 clinical isolates was performed by using spoligotyping and IS6110-Mtb1/Mtb2 PCR. MAIN OBSERVATIONS: Of the 29 families examined in this study, in 23 each family member was infected with the same M. tuberculosis strain. Three drug-resistant strains and two members of the Beijing family were identified. RESULTS: We found that strains within each of the 23 families had the same genetic patterns, whereas those of the strains identified in the rest 6 families were different. Among those 6 families, in 3 differentiation of the strains was obtained with both spoligotyping and IS6110-Mtb1/Mtb2 PCR analysis, while in another 3 only with spoligotyping method. CONCLUSIONS: Based on the results from this study, the two genotyping methods used were demonstrated as an efficient approach for investigating the epidemiological relatedness of TB cases.

Phylogenetic analysis of dengue viruses isolated from imported dengue patients: possible aid for determining the countries where infections occurred.

BACKGROUND: Molecular epidemiology of dengue viruses in endemic countries have been reported, but few were reported on the imported dengue cases among travelers. We analyzed dengue viruses isolated from imported dengue cases in Japan who were infected while traveling in endemic regions of the world. METHOD: We sequenced the complete envelope (E) gene of 33 dengue virus strains isolated from patients returning from Asia, Oceania, South Pacific islands, and South America to Japan where no domestic dengue virus infection occurs. We then performed phylogenetic analysis to define the geographic origin of isolated viruses. Moreover, we compared the genomes of isolated dengue viruses with those of the strains already deposited in the GenBank database. RESULT: The isolates are clustered into expected genotypes, confirming that the viruses originated from the visited countries. When patients visited more than one country during a single trip, the countries where the infection occurred were also determined for four of the six patients. There were three isolates, which were different genotypes from those previously isolated in visited countries. CONCLUSIONS: The study demonstrates that many dengue virus strains are introduced into Japan and that phylogenic analysis of isolated dengue viruses is a unique technique to determine the countries where infection occurred. Travelers carry viruses and provide important and unique information for clarifying dengue virus trait and its dissemination.

Manual de procedimientos para el control de la enfermedad de chagas / Manual of procedures pra the control of the chagas illness

Presenta Manual de Procedimientos para el Control de la enfermedad de Chagas, el cual es el resultado de una revisión bibliográfica exhaustiva sobre el tema y parte de un proceso de consulta y encuentros técnicos surgidos ante la necesidad imperiosa de estandarizar metodologías, que permitan unificar criterios y aplicar los conocimientos adquiridos en el control de ésta parasitosis, en aras de mejorar el abordaje, manejo, seguimiento clínico y de laboratorio de los pacientes chagásicos e implementar paralelamente acciones de control vectorial acertadas en las  areas de mayor riesgo de transmisión. El principal propósito de este Manual, es servir de guía y material de consulta diaria al personal médico, paramédico y técnico que labora en las distintas unidades de salud endémicas del país, lo que sin lugar a dudas redundar  a corto y mediano plazo en una mejor calidad de la atención que actualmente brindan los servicios de salud pública a los pacientes diagnosticados con enfermedad de chagas...

T cell-based tracking of multidrug resistant tuberculosis infection after brief exposure.

Molecular epidemiology indicates significant transmission of Mycobacterium tuberculosis after casual contact with infectious tuberculosis cases. We investigated M. tuberculosis transmission after brief exposure using a T cell-based assay, the enzyme-linked-immunospot (ELISPOT) for IFN-gamma. After childbirth, a mother was diagnosed with sputum smear-positive multidrug-resistant tuberculosis. Forty-one neonates and 47 adults were present during her admission on the maternity unit; 11 weeks later, all underwent tuberculin skin testing (TST) and ELISPOT. We correlated test results with markers of exposure to the index case. The participants, who were asymptomatic and predominantly had no prior tuberculosis exposure, had 6.05 hours mean exposure (range: 0-65 hours) to the index case. Seventeen individuals, including two newborns, were ELISPOT-positive, and ELISPOT results correlated significantly with three of four predefined measures of tuberculosis exposure. For each hour sharing room air with the index case, the odds of a positive ELISPOT result increased by 1.05 (95% CI: 1.02-1.09, p = 0.003). Only four adults were TST-positive and TST results did not correlate with exposure. Thus, ELISPOT, but not TST, suggested quite extensive nosocomial transmission of multidrug-resistant M. tuberculosis after brief exposure. These results help to explain the apparent importance of casual contact for tuberculosis transmission, and may have implications for prevention.

Haemophilus ducreyi: clinical features, epidemiology, and prospects for disease control.

Haemophilus ducreyi is the causative agent of the genital ulcer disease chancroid. Chancroid is common in developing countries and facilitates human immunodeficiency virus transmission. In this review, the clinical features, epidemiology, and prospects for disease control are discussed in the context of experimental and natural infection of humans.

[AIDS patients with an unclassified risk factor for HIV]. / Enfermos de SIDA con factor de riesgo del VIH no clasificado.

OBJECTIVES: In the surveillance of the AIDS epidemic via registries there is a small proportion of cases whose route of HIV transmission is unknown (5% for Catalonia, Spain). For reclassification purposes, the aim of this study is to detect similarities between these cases with "not qualified risk" (NQR) with the other main HIV transmission groups. METHODS: All Aids cases (> 12 years) resident in Catalonia and reported between 1988 and 1996 to the AIDS registry (n = 8,559) were compared according to their distribution of "age at diagnosis" and "first indicative AIDS disease". ANOVA and log-linear regression models were applied separately by sex. RESULTS: Evidence of similarity with the NQR group was only found for men; in terms of age at diagnosis, the NQR group was similar to both groups of sexual transmission whilst in terms of Aids indicative disease it was similar to the heterosexual transmission group. As from 1994, a reduction in the incidence of NQR cases was observed and coincided with an increase in the heterosexual group. CONCLUSIONS: According to the characteristics of the NQR cases, it can be concluded that all cases acquired HIV via one of the classic routes of infection, primarily through heterosexual contacts. For this reason, it is advisable that the criteria that define heterosexual HIV transmission be relaxed.

Effect of gender, age, transmission category, and antiretroviral therapy on the progression of human immunodeficiency virus infection using multistate Markov models. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.

This article illustrates the use of time-homogeneous Markov models with covariates to estimate the AIDS incubation period distribution from prevalent cohorts and to evaluate the effect of factors such as gender, age, human immunodeficiency virus (HIV) transmission category, and antiretroviral therapy on disease progression. We applied this methodology to the analysis of data from a cohort of 3,027 patients enrolled from a hospital-based surveillance system of HIV infection in the Bordeaux University Hospital and four secondary public hospitals in southwestern France. A total of 998 individuals (33%) progressed to AIDS during a median follow-up period of 34 months. Based on a progressive three-state Markov model, the estimated mean and median incubation periods were 9.1 years [95% confidence interval (CI) = 8.7-9.6] and 7.5 years (95% CI = 7.2-7.9), respectively. Our analyses showed a similar disease progression in men and women; we observed a more rapid progression for older subjects compared with younger ones and for homosexual men compared with heterosexuals, intravenous drug users, and transfusion recipients, who had similar disease progression rates after adjusting for age. The use of antiretroviral therapy appeared to slow disease progression. Moreover, the results indicated that a combination therapy of zidovudine with another antiretroviral drug may be more efficient than zidovudine monotherapy.

Redefining the growth of the heterosexual HIV/AIDS epidemic in Chicago.

UNLABELLED: A dramatic shift in the relative distribution of the five categories of heterosexual transmission for AIDS cases diagnosed in Chicago since 1991 prompted a mode-of-transmission validation study of what had become the most frequently reported heterosexual exposure: heterosexual relations with a person with AIDS (PWA) or documented HIV infection whose risk is not specified. METHODS: For 395 cases with originally reported heterosexual exposure, one or more of three supplemental data sources were employed: medical records were reviewed, medical providers were interviewed, and patients or proxies (i.e., spouse, significant other, or family member) were interviewed when possible. When reported HIV exposure could not be validated or reclassified, the transmission category employed was "no identifiable risk" (NIR). RESULTS: Eighty-five percent (336 of 395 cases) were reclassified into different transmission categories. Most notably, 69% (272 of 395 cases) were reclassified into transmission categories that did not involve heterosexual contact, including NIR. The cumulative percentage of cases attributable to heterosexual contact declined from 8% to 5% as a result of reclassification. Additionally, reclassification resulted in a reduction of nearly 50% in the number of AIDS cases attributable to heterosexual contact diagnosed in 1993 and 1994. CONCLUSIONS: In Chicago, an emerging problem in AIDS surveillance appears to be the use of an ambiguous heterosexual exposure category as a default when other information is not readily available. This study has found the growth in AIDS cases among persons exposed to HIV through heterosexual contact to be much slower than previously perceived. This finding may have important implications for the national debate over the extent to which heterosexual people are being infected and how funding and prevention strategies should be prioritized.

Prevalencia de la transmisión perinatal de la Hepatitis B / Prevalence of Hepatitis B perinatal transmission

La hepatitis por virus B es un problema de salud pública por su relativa alta incidencia de que portadores del virus de hepatitis B (VHB) a nivel mundial. Se ha estimado que en la transmisión del VHB de madre a hijo hay un 90 por ciento de posibilidad de ser un portador crónico, la mayoría podrían luego presentar enfermedad crónica del hígado, cirrosis o carcinoma hepatocelular primario. En nuestro país existen pocos trabajos publicados, donde se ha señalado la baja prevalencia de HBsAg y HBeAg en mujeres embarazadas. Con la finalidad de analizar la prevalencia de madres infestadas en nuestro medio y promover la necesidad de implementar políticas de salud y prevención destinadas al control de la enfermedad, se estudiaron 157 mujeres en el último trimestre de embarazo, a las cuales se les investigó en sangre la existencia de antígeno de superficie, antígeno "e" y anti core del VHB respectivamente. En 11 (7 por ciento) de los pacientes presentaron anticore (+), de éstas 2 (1,27 por ciento) tenían antigen de superficie (+). 4 (36,36 por ciento) resultaron con anticuerpo de superficie (+) y con anticuerpo para el antígeno "e" (+) en dos de ellas. Todas las 11 pacientes resultaron con antígeno "e" (-). De los recién nacidos de madres con antígeno de superficie (+) todos fueron no reactivos para antígeno de superficie y anti core al nacer y a los tres meses de edad. Se demostró una prevalencia de HBsAg (1,27 por ciento), 2 veces mayor a la reportada en algunos trabajos de los EE.UU. La presencia de un 7 por ciento de pacientes anti core (+) nos indica un aumento de la infección por el VHB con respecto a otros en nuestro país