Long-term sequelae and epidemiology of infections

chronic persistent infections

failure to completely eliminate microbe

chronic persistent infections often lead to

shedding

chronic persistent infections enable

enable microbes to persist in the community

example of chronic persistent infection

salmonella enterica serovar typhi

salmonella enterica serovar typhi causes

typhoid fever

latent persistent infections

persistence in dormant or inactive state

example of a latent persistent infection

mycobacterium tuberculosis

what is another notorious example of developing latency?

herpes virus

malignant transformations are resulted from

viral infections

what is the route of infection regarding fecal / oral route?

organisms leave the gastrointestinal tract then transmitted in food, water, fomites

what are subclinical infections?

organisms multiply in or on host

what do subclinical infections not cause?

apparent symptoms

non-communicable infections

- infections by members of normal flora
- food poisoning due to pre-formed toxins
- infections cause by common source
- infections by organisms normally found in environment

direction transmission

pathogens move straight form one host to another

what is most common with direct transmission?

mostly for pathogens in bodily secretions

indirect transmission

moved from host to host through an intermediary

how is indirect transmission most commonly transmitted?

contaminated objects that spread disease

what is another common form of indirect transmission?

through vectors such as mosquitos

zoonoses

disease transmitted from animals to humans

how can zoonotic diseases be transmitted?

direct or vector transmission

epidemiology

the study of the causes, distribution, and control of diseases within populations

disease incidence

the number of new cases within a specified time period

- how fast is it progressing through population?

disease prevalence

total number of cases in population at given time

- how common is it in the population?

endemic

present at low but constant level

endemic disease

gonorrhea

epidemic

prevalence of infection higher than usually found in that population

what is an example of an epidemic?

influenza

pandemic

widespread infection with high attack rate

attack rate

the number of people who will become ill when a pathogen is introduced

factors that influence attack rate

- incubation rate
- population susceptibility
- individual susceptibility

longer incubation periods for an infection disease may do what?

may help its spread

general incubation period

at least 2-4 days

population susceptibility depends on

- sex
- race
- general fitness
- living conditions
- presence of underlying illnesses
- occurrence of natural disasters ; war

characteristics of emerging infectious diseases

- new or changing disease
- incidence increasing

criteria to identify an EID

- new signs and symptoms
- new diagnostic technique to identify pathogen
- local disease becomes wide spread
- rare disease becomes common
- mild disease becomes severe
- with increased life span - slow diseases found