microbiology - w3: epidemiology

epidemiology

study of the distribution & determinants of health-related states or events in populations and the application of this study to control health problems

- aims to understand the patterns, causes, & effects of diseases & other health-related phenomena

various methodologies of epidemiology

descriptive epidemiology, analytical epidemiology

descriptive epidemiology

describes the occurrence of diseases by person, place, & time

analytical epidemiology

investigates the determinants of diseases by analyzing associations between exposures & outcomes

intervention epidemiology

implementing measures to prevent or control disease outbreaks

study designs for epidemiology

observational studies & experimental trials to:

- uncover risk factors, identify vulnerable populations, & evaluate the effectiveness of interventions

viruses

diverse & can infect organisms ranging from bacteria to humans; come in various shapes & sizes, with genomes made of either DNA or RNA

DNA viruses

herpes simplex virus (HSV), human papillomavirus (HPV), varicella-roster virus (VSV)

- DNA viruses have genomes composed of double-stranded DNA

- replicate their genetic material using the host cell's DNA replication machinery

RNA viruses

influenza virus, human immunodeficiency virus (HIV), hepatitis C virus (HCV)

- RNA viruses have genomes composed of single-stranded RNA

- have RNA genomes & use RNA-dependent RNA polymerase to replicate

- further classified into positive-sense RNA viruses, negative-sense RNA viruses, & retroviruses

retroviruses

human immunodeficiency virus (HIV), human T-cell lymphotropic virus (HTLV)

- contains RNA genomes that are reverse transcribed into DNA upon infection of the host cell; long-term infection

- unique group of RNA viruses that undergo reverse transcription to produce DNA copies of their genomes, which integrate into the host cell's genome

common viruses

- respiratory viruses: influenza virus, respiratory syncytial virus (RSV), adenovirus, rhinovirus

- gastrointestinal viruses: norovirus, rotavirus, hepatitis A virus

- sexually transmitted infections (STIs): herpes simplex virus (HSV), human papillomavirus (HPV), human immunodeficiency virus (HIV)

sexually transmitted infections (STIs)

viruses transmitted through sexual contact & can have serious health consequences if left untreated

- herpes simplex virus (HSV): which causes genital herpes; characterized by painful genital sores

- human papillomavirus (HPV): which can lead to genital warts & various cancers, including cervical cancer

- human immunodeficiency virus (HIV): which can result in acquired immunodeficiency syndrome (AIDs) & immune system failure & susceptibility to opportunistic infecitons

viral transmission

occurs through various routes, including direct contact, indirect contact, respiratory droplets, the fecal-oral route, & vector-borne transmission

modes of transmission

direct contact, indirect contact, respiratory droplets, fecal-oral route, vector-borne transmission

direct contact

transmission occurs through physical contact between an infected individual & a susceptible host, such as through skin-to-skin contact or sexual intercourse

indirect contact

transmission occurs through contact with contaminated surfaces or objects, such as doorknobs, utensils, or medical equipment

respiratory droplets

transmission occurs through respiratory droplets expelled when an infected individual coughs, sneezes, or talks, leading to inhalation by nearby individuals

fecal-oral route

transmission occurs through ingestion of food or water contaminated with fecal matter containing viral particles

Vector-Borne Transmission

transmission occurs through the bite of an arthropod vector, such as mosquitoes or ticks, carrying the virus

factors for viral transmission

population density, social behavior, immunity levels, travel patterns, & healthcare infrastructure

influence the spread of viruses within communities & across populations

factors affecting viral spread

population density, social behavior, immunity levels, travel & migration, healthcare & infrastructure

population density

higher population density increases the likelihood of person-to-person transmission, especially in crowded urban areas

social behavior

practices such as close contact, sharing of utensils, & poor hygiene can facilitate viral transmission.

immunity levels

presence of immune individuals within a population can limit the spread of a virus through herd immunity

travel & migration

movement of individuals between regions or countries can facilitate the spread of viruses across geographical boundaries

healthcare infrastructure

access to healthcare services and implementation of infection control measures can influence the containment of viral outbreaks

community & population control measures

vaccination programs, public health education, surveillance & monitoring, vector control, international collaboration

vaccination programs

immunization can prevent viral infections & contribute to herd immunity, reducing the overall transmission within a population

public health education

promoting awareness of preventive measures, such as hand hygiene, respiratory etiquette, & safe sexual practices, can help mitigate viral spread

surveillance & monitoring

timely detection & reporting of viral outbreaks enable rapid response measures, including quarantine, contact tracing, and treatment

international collaberation

cooperation between countries & global health organizations is essential for coordinating responses to pandemics & facilitating the sharing of resources & expertise

control measures to mitigate viral transmission

vaccination programs, public health education campaigns, surveillance & monitoring systems, vector control efforts, & international collaboration

key concepts of epidemiology

incidence, prevalence, outbreak, epidemic, pandemic, descriptive epidemiology, analytical epidemiology, intervention epidemiology

incidence

the number of new cases of a disease occurring in a population within a specified period

prevalence

the proportion of a population found to have a disease at a specific time

outbreak

the occurrence of cases of a disease in excess of what would normally be expected in a defined community, geographical area, or season

epidemic

an outbreak of a disease that affects many individuals in a community or population at the same time

pandemic

an epidemic occurring worldwide or over a very wide area, crossing international boundaries, and usually affecting a large number of people

application of epidemiology

role in public health by informing disease prevention strategies, guiding healthcare policy decisions, & evaluating the effectiveness of interventions such as vaccination programs & infection control measures