High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico.

OBJECTIVES: To evaluate the performance of rapid influenza diagnostic tests (RIDT) and influenza vaccines' effectiveness (VE) during an outbreak setting. METHODS: We compared the performance of a RIDT with RT-PCR for influenza virus detection in influenza-like illness (ILI) patients enrolled during the 2016/17 season in Mexico City. Using the test-negative design, we estimated influenza VE in all participants and stratified by age, virus subtype, and vaccine type (trivalent vs quadrivalent inactivated vaccines). The protective value of some clinical variables was evaluated by regression analyses. RESULTS: We enrolled 592 patients. RT-PCR detected 93 cases of influenza A(H1N1)pdm09, 55 of AH3N2, 141 of B, and 13 A/B virus infections. RIDT showed 90.7% sensitivity and 95.7% specificity for influenza A virus detection, and 91.5% sensitivity and 95.3% specificity for influenza B virus detection. Overall VE was 33.2% (95% CI: 3.0-54.0; p = 0.02) against any laboratory-confirmed influenza infection. VE estimates against influenza B were higher for the quadrivalent vaccine. Immunization and occupational exposure were protective factors against influenza. CONCLUSIONS: The RIDT was useful to detect influenza cases during an outbreak setting. Effectiveness of 2016/17 influenza vaccines administered in Mexico was low but significant. Our data should be considered for future local epidemiological policies.

[An unusual outbreak of histoplasmosis in residents of the state of Mexico]. / Brote inusual de histoplasmosis en residentes del estado de México.

OBJECTIVE: The aim of this study was to establish whether there was a histoplasmosis outbreak among a group of residents of Naucalpan (State of Mexico, a non-endemic area for histoplasmosis) and to ascertain the source through which they were infected. MATERIAL AND METHODS: Anyone associated with the Index Case in the same period with a flu-like infection was considered as a suspected case. Diagnosis was confirmed by clinical examination positive, cultures and positive immunological tests. Date and form of potential exposure were obtained through interviews. Material potentially contaminated with bird or bat droppings was sought and analyzed by PCR. RESULTS: The outbreak was associated with a trip to El Tamarindo (Veracruz, near the Gulf of Mexico). Patients got sick after digging a hole in the floor inside a house where a treasure had been supposedly buried by a death relative. The pathogen was detected in soil samples at 10 cm below the surface. CONCLUSIONS: The study showed that patients contracted histoplasmosis in El Tamarindo, a community where there had been no prior cases of this disease.

Reducing occurrence and severity of pneumonia due to pandemic H1N1 2009 by early oseltamivir administration: a retrospective study in Mexico.

BACKGROUND: Anti-viral treatment has been used to treat severe or progressive illness due to pandemic H1N1 2009. A main cause of severe illness in pandemic H1N1 2009 is viral pneumonia; however, it is unclear how effective antiviral treatment is against pneumonia when administered >48 hours after symptom onset. Therefore, we aimed to determine how time from symptom onset to antiviral administration affected the effectiveness of antiviral treatment against pneumonia due to pandemic (H1N1) 2009. METHODS/PRINCIPAL FINDINGS: A retrospective medical chart review of 442 patients was conducted in a hospital in Mexico. Subjects had tested positive for pandemic H1N1 2009 virus by real-time reverse-transcriptase-polymerase-chain-reaction and were administered oseltamivir. Median time from symptom onset to oseltamivir administration was 5.0 days (range, 0-43). 442 subjects, 71 (16.1%) had severe pneumonia which required mechanical ventilation, 191 (43.2%) had mild to moderate pneumonia, and 180 (40%) did not have pneumonia. Subjects were divided into four groups based on time to oseltamivir administration: ≤2, 3-7, 8-14, and >14 days. Severity of respiratory features was associated with time to treatment, and multivariate analysis indicated that time to oseltamivir administration was associated with severity of respiratory features. A proportional odds model indicated that 50% probability for occurrence of pneumonia of any severity and that of severe pneumonia in patients who would develop pneumonia reached at approximately 3.4 and 21 days, respectively, after symptom onset. Patients with a shorter time to oseltamivir administration were discharged earlier from the hospital. CONCLUSIONS: Earlier initiation of oseltamivir administration after symptom onset significantly reduced occurrence and severity of pneumonia and shortened hospitalization due to pandemic H1N1 2009. Even when administered >48 hours after symptom onset, oseltamivir showed considerable potential for reducing pneumonia. Application of these results would benefit patients affected by future influenza pandemics.