Article

The ecology of climate change and infectious diseases

Western Ecological Research Center, U.S. Geological Survey, Marine Science Institute, University of California, Santa Barbara, California 93106, USA.
Ecology (Impact Factor: 5). 05/2009; 90(4):888-900. DOI: 10.1890/08-0079.1
Source: PubMed

ABSTRACT The projected global increase in the distribution and prevalence of infectious diseases with climate change suggests a pending societal crisis. The subject is increasingly attracting the attention of health professionals and climate-change scientists, particularly with respect to malaria and other vector-transmitted human diseases. The result has been the emergence of a crisis discipline, reminiscent of the early phases of conservation biology. Latitudinal, altitudinal, seasonal, and interannual associations between climate and disease along with historical and experimental evidence suggest that climate, along with many other factors, can affect infectious diseases in a nonlinear fashion. However, although the globe is significantly warmer than it was a century ago, there is little evidence that climate change has already favored infectious diseases. While initial projections suggested dramatic future increases in the geographic range of infectious diseases, recent models predict range shifts in disease distributions, with little net increase in area. Many factors can affect infectious disease, and some may overshadow the effects of climate.

1 Follower
 · 
95 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study describes the occurrence and magnitude of latent mycobacterial infections and other pathogens in delta smelt (Hypomesus transpacificus), an endemic fish in the San Francisco Estuary (SFE). Our current knowledge on subclinical infections is characterized by the presence of mycobacterial DNA and absence of clinical signs and Mycobacterium. In our previous studies however, we showed that handling and increased water temperature, stress factors frequently encountered in captivity, have altered infections from benign to severe mycobacteriosis. In the current study, sub adult and adult smelt captured from August 2011 to May 2012 in the SFE were analyzed for presence of bacterial and viral agents (n=741) using standard isolation and culture techniques and Mycobacterium qPCR (n=237). Although mycobacteriosis, Mycobacterium, and virus were not observed in all of the fish examined, 96% of the smelt were positive for mycobacterial DNA. Higher pathogen scores and mycobacterial gene copy numbers were observed in smelt from anthropogenically impacted sites, isolated tributaries, and adult fish. Smelt captured in low salinity zone (1–6 practical salinity units, psu), the preferred habitat in summer and fall, had more infections (higher pathogen scores and mycobacterial gene copy numbers) compared to other salinity regions. Harboring mycobacterial DNA and bacterial pathogens are robust indicators of the cumulative effect of multiple stressors on delta smelt health and the ecological conditions of habitats in the SFE. These findings may provide a foundation in our current understanding of microbial infections in smelt and their potential contribution to health and conservation efforts of this threatened species. mycobacteriosis, have not been observed among smelt captured in their natural habitats in the SFE, smelt harboring Mycobacterium DNA are predominant [8a–8e]. In captivity, infections can progress from dormant to disease when wild cohorts are subjected to intensive culture conditions and increased water temperature (≥16°C) [8]. Mycobacteriosis affects a wide range of freshwater and marine aquatic organisms [9,10] to the extent that all fish species are vulnerable to the disease [11]. Epizootics of mycobacteriosis have impacted many resident fish species in the Chesapeake Bay [12,13], an estuarine ecosystem altered by anthropogenic inputs as the SFE. The purpose of this study is to evaluate the nature and extent of subclinical mycobacterial infections and other bacterial and viral pathogens in delta smelt within the SFE and its tributaries. In cooperation with ongoing fish monitoring surveys, subadult and adult delta smelt were captured across salinity regions and habitats and analyzed by sampling months, location, and salinity zones to determine for potential association of these factors with infection occurrence and severity. Methods Fish sampling and processing This study is part of an ongoing project with a broader goal of evaluating the health of delta smelt inhabiting the low salinity zone (1–6 psu, practical salinity units) of the SFE. In collaboration with
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Urban heat islands are characterized by high land surface temperature, low humidity, and poor vegetation, and considered to favor the transmission of the mosquito-borne dengue fever that is transmitted by the Aedes aegypti mosquito. We analyzed the recorded dengue incidence in Sao Paulo city, Brazil, in 2010–2011, in terms of multiple environmental and socioeconomic variables. Geographical information systems, thermal remote sensing images, and census data were used to classify city areas according to land surface temperature, vegetation cover, population density, socioeconomic status, and housing standards. Of the 7415 dengue cases, a majority (93.1%) mapped to areas with land surface temperature >28 °C. The dengue incidence rate (cases per 100,000 inhabitants) was low (3.2 cases) in high vegetation cover areas, but high (72.3 cases) in low vegetation cover areas where the land surface temperature was 29 ± 2 °C. Interestingly, a multiple cluster analysis phenogram showed more dengue cases clustered in areas of land surface temperature >32 °C, than in areas characterized as low socioeconomic zones, high population density areas, or slum-like areas. In laboratory experiments, A. aegypti mosquito larval development, blood feeding, and oviposition associated positively with temperatures of 28–32 °C, indicating these temperatures to be favorable for dengue transmission. Thus, among all the variables studied, dengue incidence was most affected by the temperature.
    Brazilian Journal of Infectious Diseases 03/2015; 19(2):146-155. · 1.10 Impact Factor
  • Source

Full-text

Download
65 Downloads
Available from
May 22, 2014