Table 1.

Major risk factors and communicable diseases identified among people experiencing homelessness

Risk factor	Modes of disease transmission	Communicable disease (examples)
Inadequate access to personal hygiene
Handwashing and toilet facilities	Fecal-oral	Hepatitis A Shigella Norovirus
Bathing and skin care	Direct inoculation	Skin and soft tissue infections (SSTIs) Group A streptococcal infections
Laundry	Ectoparasite infestations Vector-borne illnesses	Lice Scabies Bed bugs Bartonella quintana (louse-borne)
Inadequate access to resting places
Pressure injury from lying on hard surfaces	Direct contact	SSTIs
Lower extremity stasis dermatitis from lack of places to lie flat	Direct contact	SSTIs
Congregate settings and increased exposures (shelters, tent dwellings)	Droplet Airborne Direct contact Fomites	Norovirus Influenza Tuberculosis Hepatitis A
Exposure to disease vectors	Vector-borne	Mosquito-borne illnesses, Typhus (flea-borne)
Behavioral risks
Exchange of sex for money  Sex while high  Sexual assault	Sexual contact	Syphilis Gonorrhea Chlamydia HIV Hepatitis B
Comorbid medical conditions
Substance abuse, including alcohol, intravenous drug use	Blood-borne Skin disruption	HIV Hepatitis A Hepatitis B Hepatitis C Invasive group A streptococcal infections Methicillin resistant Staphylococcus aureus
Mental illness	Increase risk behavior Decreased self-care Delays in care	May exacerbate multiple conditions
Limited access to healthcare
Limited preventive services	Decreased vaccinations Increased vulnerability to infections	Shingles Pneumonia Hepatitis A
Poorly controlled chronic conditions	Decreased immunity Increased vulnerability to infections	SSTIs
Low health literacy	Delays in care	Pneumonia requiring hospitalisation due to late presentation
Limited medical care	Decreased secondary and tertiary prevention Lack of treatment due to inability to find affected individuals	Severe sequelae of minor medical issues. For example, septic shock from cellulitis related to infected wounds from venous stasis dermatitis.