Noninvasive monitoring of hepatic damage from hepatitis C virus infection.

The mathematical model for the dynamics of the hepatitis C proposed in Avendaño et al. (2002), with four populations (healthy and unhealthy hepatocytes, the viral load of the hepatitis C virus, and T killer cells), is revised. Showing that the reduced model obtained by considering only the first three of these populations, known as basic model, has two possible equilibrium states: the uninfected one where viruses are not present in the individual, and the endemic one where viruses and infected cells are present. A threshold parameter (the basic reproductive virus number) is introduced, and in terms of it, the global stability of both two possible equilibrium states is established. Other central result consists in showing, by model numerical simulations, the feasibility of monitoring liver damage caused by HCV, avoiding unnecessary biopsies and the undesirable related inconveniences/imponderables to the patient; another result gives a mathematical modelling basis to recently developed techniques for the disease assessment based essentially on viral load measurements.

Risk factors and the prevalence of leptospirosis infection in a rural community of Chiapas, Mexico.

A cross-sectional study was conducted in Mapastepec, a rural community of the southern state of Chiapas, Mexico. The overall prevalence of leptospirosis infection in 1169 subjects was 37.7% [95% confidence intervals (95% CI) 34.9-40.5]. The main risk factors related to leptospirosis infection were flooding, mainly if subjects had a skin cut or abrasion [odds ratio (OR) 4.2; 95% CI 3.1-5.7], having domestic animals, either dogs and/or cats (OR 1.3; 95% CI 0.96-1.8) or cattle and/or pigs (OR 1.9; 95% CI 1.3-2.7), contact with animal excreta with no protection and with a skin cut or abrasion (OR 2.3; 95% CI 1.1-4.6). Those subjects with a dengue infection in the previous year had also an excess risk (OR 1.4; 95% CI 0.9-2.0). Mapastepec is a previously unknown area with high endemicity. Specific preventive measures should be adopted to prevent any contact with infected animals, and animal immunization should also be implemented. There is need of an epidemiological surveillance system to allow proper diagnosis.

Microbiological findings in febrile neutropenia.

BACKGROUND: This study was carried out to assess the isolation rate of bacterial and fungal causative agents in Mexican neutropenic adults with hematological neoplasia. METHODS: A prospective observational survey involving 120 consecutive episodes of febrile neutropenia during 1 year was carried out. These episodes were observed in 630 patients discharged with diagnoses of leukemia or lymphoma, or after bone-marrow transplantation. RESULTS: At least one pathogen was isolated in 42 of 120 episodes (35%), and was present in 39 patients with acute myeloid leukemia (AML) (43%), acute lymphoblastic leukemia (ALL) (23%), and in patients who underwent bone-marrow transplantation (20%). Primary bacteremia was the most frequent cause of fever (24 episodes, 57%), followed by intravascular device-related infections (5 episodes, 17%), and soft-tissue infections (5 episodes, 15%). Escherichia coli (33%) was the most frequently isolated agent of primary bacteremia, followed by coagulase-negative Staphylococcus (29%), and Klebsiella oxytoca (16%). Fungal infection was responsible for five events (4%): two episodes of pneumonia (Penicillium marneffei and Aspergillus fumigatus, one event each); two cases of fungemia, one due to Candida tropicalis and one to Rhodotorula gluttinis, and one cryptococcal meningitis event. CONCLUSIONS: The isolation rate, approximately 30%, was in accordance with previous reports; similar percentages of Gram-positive and Gram-negative isolates were found. A remarkably low rate of viridans group streptococci and fungal agents was observed, despite the fact that neutropenia is the main risk factor for infection due to these agents. Studies reporting local microbiological findings are necessary because they support an antibiotic choice for prophylaxis or therapy more accurately than reports from other areas.