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4.9 Infectious Disease

Infectious disease was identified in the 2008 Valley County Pre-Disaster Mitigation Plan, labeled as “Communicable Disease” and was also identified as one of the hazards to be included in this plan update. Analyses included in this plan update include a more in-depth look at what infectious disease is, the history of it within Valley County, and the potential it has to impact residents. A definition of infectious disease is provided prior to taking a closer look at the effect infectious disease has on Valley County in order to provide the reader with knowledge of the hazard.

Infectious diseases, sometimes called communicable diseases, are illnesses caused by organisms such as bacteria, viruses, fungi and parasites. Sometimes the illness is not due to the organism itself, but rather a toxin that the organism produces after it has been introduced into a human host. The infectious disease may be transmitted (spread) either by one infected person to another, from an animal to a human, from an animal to an animal, or from an inanimate object to an individual.
Human Diseases

One of the most common communicable diseases is influenza. Influenza is a contagious, upper respiratory disease caused by many different strains of influenza viruses. In 1979 and again in late 2003, a flu epidemic hit the U.S. infecting hundreds of people. The swine flu (H1N1) pandemic of 2009 caused a number of fatalities in the country. The 2012-2013 flu outbreaks in Montana claimed 15 lives. The best way to prevent the flu is by getting a flu vaccine each year.

Agriculture dominates Montana’s economy contributing $3.046 billion per year with $1.78 billion coming from crops and $1.27 billion coming from livestock (USDA National Agriculture Statistics Service, 2013). Wheat is Montana’s most important crop followed by hay, barley, and sugar beets. Montana’s most important livestock commodities are cattle and calves, followed by hogs and pigs, and sheep and lambs. The security of the state’s crop and livestock industry is of paramount importance to Montana’s economy. Some of the animal diseases with the potential to threaten the state’s agricultural industry include anthrax, brucellosis, chronic wasting disease, foot and mouth disease and mad cow (BSE) disease. Many plant pests are sporadic in their occurrence cycling with environmental conditions such as dry or wet cycles. However, major insect pests such as alfalfa weevil, wheat stem sawfly, wireworms, cutworm species, grasshoppers and cereal leaf beetle are likely to attain pest status in the state each year.

4.9.1 Infectious Disease Risk

While the probability of infectious diseases is highly likely in Valley County, its relative impact is low and thus the overall risk for infectious diseases in Valley County is little to none. Data from 2013 for the Valley County was used to determine this risk. Data was not available for city, town or community, so therisk was determined for the county as a whole. The table below provides the name of each of the cities in the county, the probability that infectious disease will have an impact on that jurisdiction, the impact potential, as well as the overall risk calculated by the determine probability and impact ratings.

Table 61: Infectious Disease Risk by City in Valley County

Infectious Disease
City	Probability	Impact	Risk
Glasgow	Highly Likely	Low	Little to No
Fort Peck	Highly Likely	Low	Little to No
Nashua	Highly Likely	Low	Little to No
Opheim	Highly Likely	Low	Little to No
Valley County*	Highly Likely	Low	Little to No
Total	Highly Likely	Low	Little to No

*Valley County information takes into account unincorporated areas of the County.

The 2015 update utilized the Risk =Frequency x Consequence (R = FC) formula and each jurisdiction has its own unique risk score based on the 28 points of data analyzed. The risk determined for the 2015 update represents a significant change from the previous plan. This update indicated the overall risk for Valley County is little to none.

The last plan update completed in July 2008 indicated that infectious disease had the potential to have a moderate impact on Valley County.

4.9.2 Infectious Disease History in Valley County

The following data represents communicable diseases that have been reported as part of the Montana Communicable Disease Case Counts by Jurisdiction of Residence for 2013 provided by the Montana Department of Health. 
The infectious disease occurrences which were the highest in the Valley County in 2013 were Chlamydia and Varicella (Chickenpox). There were 37 communicable diseases included in 2013, but occurrences in Valley County were only reported in the following 6 diseases.

Table 62: Communicable Disease and Number of Occurrences

Communicable Disease Name	Count for Valley County
Chlamydia	14
Legionellosis	1
Streptococcus pneumonia	1
Varicella (Chickenpox)	5
Hepatitis C, Chronic*	3
West Nile	2

Source: Montana Communicable Disease Case County by Jurisdiction of Residence, 2013

4.9.3Presidential Declared Disasters for Infectious Disease

No presidential declared disasters for infectious disease in the past 5 years.

4.9.4 Mitigation Actions in the Past Five Years

Mitigation actions for infectious disease from the 2008 Valley County Pre-Disaster Mitigation Plan stated the mitigation action for infectious disease was to mitigate the spread of communicable diseases by developing disease education materials and improving disease surveillance measures. In this iteration of the plan, most of these projects will be continued.

One project that was completed was in 2016. The Community Assessment for Public Health Emergency Response (CASPER) was completed in 2016 for Valley County. CASPER is an epidemiologic technique designed to provide household-level information and be efficiently and rapidly deployed with minimum resources. CASPERs can be conducted to assess the effect of a disaster on a population, to determine the health status and basic needs of an affected population, to evaluate response and recovery efforts, to gain a better understanding of the community for CHAs, and to practice the CASPER technique as part of a preparedness exercise. The interview teams conducted 121 interviews, yielding a completion rate of 86%. The 121 interviewed households were a sample of the 4,879 total households in Valley County. Data collected included demographic aspects of Valley County, important aspects of community health, communication, health questions, physical activity, healthy eating, health care and health care access, preventative services, oral health, injury, mental health, emergency preparedness, and problems in Valley County. Overall, the assessment determined that areas for potential public health interventions include continued efforts to decrease smoking, improved seat belt usage, increased influenza vaccine coverage, and to increase routine dental care. Improvements can be made to increase awareness of programs to help pay for health care expenses and to ensure and improve access to health care services.

4.9.5 Vulnerability

In Valley County, there are certain populations of people who are more susceptible to infectious disease. The elderly and children are at an increased risk of becoming infected with airborne diseases because of weakened immune systems and spending more time in crowded settings, such as schools and nursing homes, which can allow for an easier spread of airborne diseases There is also increased therisk of tick and mosquito-transmitted diseases, such as Lyme Disease, Anaplasmosis, and West Nile Virus, because of possible exposure in forested areas of the county. Individuals who spend time outside or in these forested areas are at an increased risk.

4.9.6 Infectious Disease and Climate Change

According to the World Health Organization, changes in infectious disease transmission patterns are alikely major consequence of climate change. There are three categories of research into the linkages between climatic conditions and infectious disease transmission. The first examines evidence from the recent past of associations between climate, variability, and infectious disease occurrence. The second looks at early indicators of already-emerging infectious disease impacts of long-term climate change. The third uses the above evidence to create predictive models to estimate the future burden of theinfectious disease under projected climate change scenarios.
Types of diseases which are impacted by climate change are vector-borne and water-borne diseases. Important determinants of vector-borne disease transmission include vector survival and reproduction, the vector’s biting rate, and the pathogen’s incubation rate within the vector organism. Vectors, pathogens, and hosts each survive and reproduce within a range of optimal climatic conditions: temperature and precipitation are the most important, while sea level elevation, the wind, and daylight duration are also important. Human exposure to waterborne infections occurs by contact with contaminated drinking water, recreational water, or food. This may result from human actions, such as improper disposal of sewage wastes, or be due to weather events. Rainfall can influence the transport and dissemination of infectious agents, while temperature affects their growth and survival.

Source: World Health Organization

4.9.7 Relationship to Other Hazards

Flood and drought conditions are associated with infectious disease because food and waterborne disease outbreaks can be sparked by flood and drought conditions. Food and water can become contaminated during flood and drought conditions, which can negatively impact the public’s health. Norovirus, Salmonella, and E. coli are also associated with waterborne illness outbreaks, which are usually caused by drinking water contaminated by animal or human waste. Additionally, standing water from flooding can cause the mosquito population to increase, making West Nile Virus more likely.

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