BIO 431
HEALTH MICROBIOLOGY
C- EPIDEMIOLOGY
• Infectious diseases affect individuals, but often the infection does not occur unless the individual is part of the population. So how do pathogens spread? In this context, Epidemiology is the study of the occurrence, spread and control of the disease in populations and actually deals with public health.
The incidence of a disease
• Prevalence: Ratio of sick individuals in a population over a period of time
• Incidence: The number of cases of that disease in a population over a period of time.
• Epidemia: A disease is seen in an unusually high number of individuals in a population
• Pandemic: seeing epidemic worldwide
• Endemic (local): Disease that is constantly present in a population, usually at a low incidence
• Epidemic: Too many cases in a short period of time
• An endemic disease is constantly present at a low incidence in a specific population. In epidemics, an unusually high disease incidence occurs in a specific population.
Infectious diseases cause morbidity (disease) and can cause mortality (death). An infectious disease follows a predictable clinical profile in the host.
Disease progression
1-Infection
2- Incubation period 3-Acute period
4-Decline period 5-Recovery period
3. Acute post-clinical disease
Mortality: Incidence of death in the population Or enters a period of decline.
Solution for infectious diseases: quarantine (restriction of mobility)
• To understand how diseases spread, the pathogen reservoir must be known. Some pathogens are found in soil, water, or animals.
Other pathogens are found only in humans and ensure that they continue only through person-to-person contact. Understanding disease carriers and pathogen life cycles is essential for disease control.
• Food and water treatment regulations, vector control, immunization, quarantine, disease monitoring and pathogen eradication are public health measures that play a key role in reducing the incidence of disease.
• Natural or artificial changes in host, vector, or pathogen conditions can result in conditions that support the explosive new appearance or reappearance of some infectious diseases.
Global surveillance and response programs must be developed to protect against new epidemics and pandemics.
Nosocomial infections
• Many common microorganisms have potentials to become pathogens in hospital settings. Hospital patients are hypersensitive to infectious diseases and are exposed to a wide range of infectious agents, including opportunistic pathogens in the hospital setting. The treatment of these infections is further complicated by antibiotic resistance.
• Bioterrorism is a global hazard that develops due to the availability of easily accessible technical information and fast international travel.
Biological agents can be used as weapons by military forces or terrorist groups. Common sources such as aerosols or food and water are the most likely form of inoculation. Protection and limitation measures are based on a well- planned public health structuring. Bacillus anthracis has emerged as an important pathogen due to its use as a bioweapon.
