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  • Malaria smear positivity among Kenyan children peaks at intermediate temperatures as predicted by ecological models. Parasites & vectors Shah, M. M., Krystosik, A. R., Ndenga, B. A., Mutuku, F. M., Caldwell, J. M., Otuka, V., Chebii, P. K., Maina, P. W., Jembe, Z., Ronga, C., Bisanzio, D., Anyamba, A., Damoah, R., Ripp, K., Jagannathan, P., Mordecai, E. A., LaBeaud, A. D. 2019; 12 (1): 288


    Ambient temperature is an important determinant of malaria transmission and suitability, affecting the life-cycle of the Plasmodium parasite and Anopheles vector. Early models predicted a thermal malaria transmission optimum of 31 °C, later revised to 25 °C using experimental data from mosquito and parasite biology. However, the link between ambient temperature and human malaria incidence remains poorly resolved.To evaluate the relationship between ambient temperature and malaria risk, 5833 febrile children (<18 years-old) with an acute, non-localizing febrile illness were enrolled from four heterogenous outpatient clinic sites in Kenya (Chulaimbo, Kisumu, Msambweni and Ukunda). Thick and thin blood smears were evaluated for the presence of malaria parasites. Daily temperature estimates were obtained from land logger data, and rainfall from National Oceanic and Atmospheric Administration (NOAA)'s Africa Rainfall Climatology (ARC) data. Thirty-day mean temperature and 30-day cumulative rainfall were estimated and each lagged by 30 days, relative to the febrile visit. A generalized linear mixed model was used to assess relationships between malaria smear positivity and predictors including temperature, rainfall, age, sex, mosquito exposure and socioeconomic status.Malaria smear positivity varied between 42-83% across four clinic sites in western and coastal Kenya, with highest smear positivity in the rural, western site. The temperature ranges were cooler in the western sites and warmer in the coastal sites. In multivariate analysis controlling for socioeconomic status, age, sex, rainfall and bednet use, malaria smear positivity peaked near 25 °C at all four sites, as predicted a priori from an ecological model.This study provides direct field evidence of a unimodal relationship between ambient temperature and human malaria incidence with a peak in malaria transmission occurring at lower temperatures than previously recognized clinically. This nonlinear relationship with an intermediate optimal temperature implies that future climate warming could expand malaria incidence in cooler, highland regions while decreasing incidence in already warm regions with average temperatures above 25 °C. These findings support efforts to further understand the nonlinear association between ambient temperature and vector-borne diseases to better allocate resources and respond to disease threats in a future, warmer world.

    View details for DOI 10.1186/s13071-019-3547-z

    View details for PubMedID 31171037

  • Invasive pulmonary aspergillosis and influenza co-infection in immunocompetent hosts: case reports and review of the literature. Diagnostic microbiology and infectious disease Shah, M. M., Hsiao, E. I., Kirsch, C. M., Gohil, A., Narasimhan, S., Stevens, D. A. 2018


    Invasive pulmonary aspergillosis (IPA) is classically considered an illness of severely immunocompromised patients with limited host defenses. However, IPA has been reported in immunocompetent but critically ill patients. This report describes two fatal cases of pathologically confirmed IPA in patients with influenza in the intensive care unit. One patient had influenza B infection, whereas the other had influenza A H1N1. Both patients died despite broad-spectrum antimicrobials, mechanical ventilation, and vasopressor support. Microscopic and histologic postmortem examination confirmed IPA. Review of the English language and foreign literature indicates that galactomannan antigen testing and classic radiologic findings for IPA may not be reliable in immunocompetent patients. Respiratory cultures which grow Aspergillus species in critically ill patients, particularly those with underlying influenza infection, should not necessarily be disregarded as contaminants or colonizers. Further research is needed to better understand the immunological relationship between influenza and IPA for improved prevention and treatment of influenza and Aspergillus co-infections.

    View details for PubMedID 29454654

  • ARBOVIRUS AND MALARIA CO-INFECTIONS AMONG FEBRILE KENYAN CHILDREN Shah, M., Sahoo, M., Krystosik, A., Mutuku, F., Ndenga, B., Otuka, V., Ronga, C., Chebii, P., Maina, P., Jembe, Z., Pinsky, B., LaBeaud, A. AMER SOC TROP MED & HYGIENE. 2018: 162–63
  • RISK FACTORS FOR MALARIA POSITIVITY AMONG FEBRILE CHILDREN AT FOUR HETEROGENEOUS KENYAN CLINICS Shah, M., Krystosik, A., Caldwell, J., Mutuku, F., Ndenga, B., Otuka, V., Ronga, C., Chebii, P., Maina, P., Jembe, Z., Ripp, K., Vora, R., Jagannathan, P., LaBeaud, D. AMER SOC TROP MED & HYGIENE. 2018: 553–54
  • Group B Streptococcus Colonization by HIV Status in Pregnant Women: Prevalence and Risk Factors JOURNAL OF WOMENS HEALTH Shah, M., Aziz, N., Leva, N., Cohan, D. 2011; 20 (11): 1737-1741


    To examine the prevalence of and risk factors for group B Streptococcus (GBS) colonization in an HIV-infected and uninfected pregnant population.We conducted a retrospective double cohort study comparing the prevalence of GBS colonization between 90 HIV-infected and 1947 uninfected women attending prenatal care at San Francisco General Hospital, an urban public hospital affiliated with the University of California, San Francisco. We investigated risk factors for GBS colonization, including age, ethnicity, obesity, diabetes, alcohol or illicit drug use, tobacco use, degree of immunosuppression, and infectious comorbidities.In the multivariable analysis, HIV serostatus was not independently associated with GBS colonization (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.62-1.62). Obesity (OR 1.53, 95% CI 1.13-2.07), white race (OR 1.89, 95% CI 1.30-2.75), and black race (OR 1.78, 95% CI 1.32-2.41) were independently associated with increased maternal GBS colonization. Among HIV-infected women, univariate analysis showed an association between GBS colonization and detectable HIV-1 plasma viral load at the time of rectovaginal culture (p<0.05). Mean CD4 lymphocyte count, infectious comorbidities, and HIV-1 plasma viral load at delivery were not associated with GBS colonization in HIV-infected pregnant women.HIV-1 infection is not a risk factor for GBS colonization among an ethnically diverse pregnant population at San Francisco General Hospital, although our data suggest that among HIV-infected women, plasma HIV-1 viremia may be associated with GBS colonization. Interventions that diminish HIV-1 plasma viral load and, perhaps, genital tract shedding of HIV may be associated with a reduced risk of GBS colonization in future studies.

    View details for DOI 10.1089/jwh.2011.2888

    View details for Web of Science ID 000296924400019

    View details for PubMedID 22011210