1. Environmental Transmission of Pathogenic Microbes – why they are where they are when they are Part 2
Dr. Julie Ann Kase
Public Health Scientist – Bioterrorism and Emerging Pathogens Unit
NC State Laboratory of Public Health
What I am going to cover will be an overview of the topic and keep in mind that this topic could be expanded into a semester long course

2. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Soil microbial communities
Complex set of natural communities
10,000 species per gram of soil
Traditionally soil microbiology has focused on metabolic activities of microbes (e.g. biogeochemical cycles – nitrogen fixation)
Concern when pathogens on/in soil reach surface/ground waters or are disturbed (transmitted via air)

3. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Sources of pathogenic soil microbes
Domestic drainage/septic systems
Land applied municipal sewage
Land applied agricultural waste
Landfills
Disposable diapers and animal waste– untreated waste penetrating subsurface
Naturally occurring

4. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Although most of us don’t routinely ingest soil…
Infiltrated ground water
Surface of raw fruits & vegetables
Sampling
Surface soils
Subsurface soils
Horizontal and vertical variations
Perturbation of site, contamination
Specialized technologies for drilling and coring
Cost and expertise

5. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Survival and persistence of soil microbes
Some things to consider …
Soil type
Texture: sand>silt>clay
Moisture content: below 10% is biocidal
Adsorption to soil (esp. viruses)
Migration of microbes thru soil layers
Type and species of microbe (physiological & morphological characteristics)
Smaller microbes penetrate soil better
Virus>bacteria>protozoa

6. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Ground water recharge-
Lack of water in arid SW US has prompted actions such as the land application or injection of treated wastewater to recharge subsurface aquifers
Movement of viruses (small size=greatest potential to be transported) thru soil mostly studied
In one study, indigenous enteroviruses were found in 9m deep well, 14m from recharge basin
Movement of larger microbes (bacteria and protozoans) theoretically less

7. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne transmission
Bioaerosol –
“collection of airborne biological particles”
Droplets or particles 0.5 to 30 μm diameter
Composition will vary with source & environmental conditions
Airplane

8. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Sources: any object that can produce droplets or aerosols
Humans and other animals (cough, sneezes)
Mechanical ventilation system
Fresh and marine surface waters, showers, whirlpool baths, toilets
Splash/wave action : microbes enclosed within droplet
Soil, plants
associated with particles, dust; act as “raft”
spores
US postal letters – mail-borne attack Oct. 2001

9. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Type of microbes found in bioaerosols:
Viruses, bacteria, fungi (spores & hyphae)
Generally protozoans are too large to remain airborne

10. Some Examples of Bioaerosols
Living Source Examples
Microorganisms (microbes):
Bacteria Legionella, Anthrax, endotoxins
Fungi Histoplasma,Cyptococcus, Pencillium, Aspergillus, Stachybotrys aflatoxins,
Protozoa Naegleria, Acanthamoeba
Viruses Rhinoviruses (colds), Influenza (flu), Coronaviruses (SARS), Hantavirus
Algae Chlorococus
Green plants Ambrosia (ragweed) pollen
Arthropods Dermatophagoides (dust mites)
Mammals Horse or cat dander

11. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne Microbes and their Reservoirs – Bacteria
Legionella pneumophila
Reservoirs and amplifiers:
Hot water systems, circulating water ventilation systems (cooling towers), plumbing (e.g., shower heads), hot tubs, whirlpools, produce fresheners
Legionnaire's disease:
A bacterial pneumonia that affects the lungs and may also affect the stomach and intestines, kidneys, and central nervous system
Frequently requires hospitalization

12. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne Microbes and their Reservoirs – Bacteria
Bacillus anthracis
Reservoirs and amplifiers:
Spores are extremely resistant, 50 years or more in soil
Animal carcass – vegetative cells will sporolate when exposed to air
Person-person spread unlikely
2005: South Dakota: 11 counties: 39 outbreaks, 330 head; North Dakota: 13 counties, 86 cases
Anthrax:
Cutaneous: skin lesions from contact with spores or contaminated meat
Gastrointestinal: ingestion of spores or contaminated foods
Inhalation: often fatal, especially with inhalation of weapons-grade spores, symptoms resemble common cold, severe breathing problems, shock
is to suspect an old forgotten anthrax grave on the primary ranch. With the heavy rains, spores might have been forced to the surface, unless the rancher had been earth moving (clearing ditches, trenching, bulldozing, scrub clearing

13. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Biohazard Detection System (BDS)
Combined automated air sampling w/internal automated testing system
Sampling interval 1.5 hrs, 30 min analysis
Currently only set-up for B. anthracis spores
Used across the US in USPS PDC
BioWatch Program
Air monitors set up in last 3 yrs; 30 metro areas
Goal: detect w/in 36 hrs release of anthrax, sm pox, plague
~10 sensors per city, tested once a day
Not intended to prevent attack, hundreds of thousands of victims, instead start mass treatment
PDC = process and distribution centers

14. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne Microbes and their Reservoirs – Viruses
Coronaviruses
Reservoirs and amplifiers:
First reported in Asia 2003, global outbreak-few months spread to two dozen countries
Person-person spread – respiratory droplets travel short distances (~ 3ft)
Knowledge is still evolving
SARS:
Flu-like symptoms, most develop pneumonia
8,437 people worldwide w/ 813 deaths
US: 192 cases, none died, very little transmission among close contacts and generally did not spread thru community!!??

15. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne Microbes and their Reservoirs – Viruses
Hantaviruses
Reservoirs and amplifiers:
Wild rodents - pass it in their droppings, urine, or saliva. The common house mouse does not carry hantavirus.
Human exposure - touch rodent urine, droppings, or places where these animals have nested. Most exposed (by inhalation) when sweeping areas with dried droppings or urine
Hantavirus pulmonary syndrome:
Flu-like symptoms, most develop cough and shortness of breath
Person-to-person spread unlikely
Around in US since 1950s, took outbreak in “four corners” area of US to be recognized

16. Environmental Transmission of Pathogenic Microbes : Water, Soil, Air
Airborne Microbes and their Reservoirs – Fungi
Cryptococcus neoformans
Reservoirs and amplifiers:
Isolated from the soil worldwide, usually in association with bird droppings
Inhalation of airborne cells and/or spores
Cryptococcosis:
Initial pulmonary infection - usually asymptomatic
Disseminated infection, especially meningoencephalitis
In the United States, 85% of cases occur in HIV-infected persons