Biomedical subjects

Gerardo Chowell

Publications and source records attributed to Gerardo Chowell.

4 recordsLinked to original sources

PubMed2006

Identification of case clusters and counties with high infective connectivity in the 2001 epidemic of foot-and-mouth disease in Uruguay.

OBJECTIVE: To evaluate the influence of individual spatial units (ie, counties) on the epidemic spread of foot-and-mouth disease (FMD) virus. SAMPLE POPULATION: 163 counties in Uruguay where there was an outbreak of FMD between April 23 and July 11, 2001. PROCEDURE: A geographically referenced database was created, and the distance between counties (13,203 county pairs), road density of counties (163 counties), and time when cases were reported in those counties (11 weeks of the epidemic) were considered to assess global spatial and spatial-temporal autocorrelation, determine the contribution of links connecting pairs of counties with infected animals, and allow us to hypothesize the influence for spread during the epidemic for counties with greater than the mean infective link contributions. RESULTS: Case clusters were indicated by the Moran Iand Mantel tests during the first 6 weeks of the epidemic. Spatial lags between pairs of counties with infected animals revealed case clustering before and after vaccination was implemented. Temporal lags predicted autocorrelation for up to 3 weeks. Link indices identified counties expected to facilitate epidemic spread. If control measures had been implemented in counties with a high index link (identifiable as early as week 1 of the epidemic), they could have prevented (by week 11 of the epidemic) at least 2.5 times as many cases per square kilometer than the same measures implemented in counties with average link indices. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of spatial autocorrelation and infective link indices may identify network conditions that facilitate (or prevent) disease spread.

Animals↗

PubMed2006

Climate-based descriptive models of dengue fever: the 2002 epidemic in Colima, Mexico.

Dengue is a public health problem on the rise in many tropical regions and affects approximately 100 million people every year worldwide. In this paper, the authors retrospectively assess the association between five climatological variables and dengue incidence using data from the 2002 dengue epidemic in Colima, Mexico. Pluvial precipitation (mm), evaporation (mm), and mean, maximum, and minimum temperatures (degrees C) were obtained from local meteorological stations. The highest correlation of dengue incidence with maximum temperature was found at a lag of one month, and the highest correlation for evaporation was found at a lag of three months. A multiple-linear-regression model that includes all the climatological variables was correlated with 94 percent of the observed variance. Two simpler linear models with variables significant at the 99 percent confidence level were correlated with 88 percent (Precipitation + Evaporation) and 79 percent (Precipitation + Maximum Temperature) of the observed variance.

Dengue↗

PubMed2005

The dynamics of pulmonary tuberculosis in Colima, Mexico (1999-2002).

Tuberculosis is a public health problem in Mexico. From 1999 to 2002, we assessed retrospectively the epidemiological, clinical, and treatment characteristics of pulmonary tuberculosis in the hospitals of the Mexican Institute of Public Health in the state of Colima (Mexico). We included 184 cases diagnosed with pulmonary tuberculosis. A database containing demographic, epidemiological, and clinical information was constructed and analyzed. We estimate a median patient delay of 83 d and a mean treatment delay of 2.3 d. Of 14 cases suspected for multiresistance and microbiologically assayed, 5 were found to carry a multi-drug-resistant strain. We also found a significant association between a short patient delay and the presence of hemoptysis (p = 0.002) or dyspnea (p<0.001). 86 patients (46.8%) were sputum smear microscopy negative at the end of treatment and 40 (21.7%) completed treatment giving an overall success rate of 68.5%, which compares unfavorably with the World Health Organization target success rate of 85%. Five (2.7%) patients failed treatment, 10 (5.4%) died, 39 (21.2%) interrupted treatment, and 4 (2.2%) transferred to another reporting unit. A 2002 strategic change in drug distribution seemed to prove successful.

Adult↗

PubMed2004

Model parameters and outbreak control for SARS.

Control of the 2002-2003 severe acute respiratory syndrome (SARS) outbreak was based on rapid diagnosis coupled with effective patient isolation. We used uncertainty and sensitivity analysis of the basic reproductive number R0 to assess the role that model parameters play in outbreak control. The transmission rate and isolation effectiveness have the largest fractional effect on R0. We estimated the distribution of the reproductive number R0 under perfect isolation conditions. The distribution lies in the interquartile range 0.19-1.08, with a median of 0.49. Even though the median of R0 is <1, we found that 25% of our R0 distribution lies at R0 > 1, even with perfect isolation. This implies the need to simultaneously apply more than one method of control.

Communicable Disease Control↗