How to Say "infectious" in Spanish
The most common Spanish word for “infectious” is “contagioso” — use this word to describe a medical condition that can be passed from person to person, or to describe a personality trait or energy that easily spreads to others..
contagioso
/kon-ta-HYOH-soh//kontaˈxjoso/
Examples
Su entusiasmo es contagioso; pronto todos estaban sonriendo.
His enthusiasm is infectious; soon everyone was smiling.
Ten cuidado, el resfriado es muy contagioso.
Be careful, the cold is very contagious.
No vengas a la oficina si tienes algo contagioso.
Don't come to the office if you have something contagious.
Los médicos dicen que el virus ya no es contagioso después de tres días.
Doctors say the virus is no longer contagious after three days.
Matching the Ending
Since this is an adjective, you must change the 'o' to an 'a' when describing a feminine noun. For example: 'una enfermedad contagiosa' (a contagious illness).
Using it with 'Ser'
Even though a sickness might be temporary, we use the verb 'ser' (to be) because we are describing a characteristic of the virus or the person's current state of being able to spread it.
Describing Feelings
When used for feelings, this word usually stays with 'ser' because you are describing the quality of that feeling.
Confusing 'Infectious' and 'Contagious'
Mistake: “Using 'infeccioso' for everything.”
Correction: While similar, 'contagioso' specifically means it can spread from person to person. A bacterial infection might be 'infeccioso' but not 'contagioso' if it can't be caught by others.
Forgetting the 'g'
Mistake: “contadioso”
Correction: It is spelled with a 'g' (contagioso), coming from the word 'contagio'.
infeccioso
/een-fek-SYOH-soh//iɱ.fegˈθjo.so/
Examples
El médico advirtió sobre la naturaleza infecciosa de la bacteria.
The doctor warned about the infectious nature of the bacteria.
La gripe es un virus muy infeccioso.
The flu is a very infectious virus.
Es importante separar los residuos infecciosos del hospital.
It is important to separate the hospital's infectious waste.
Muchos agentes infecciosos se transmiten por el aire.
Many infectious agents are transmitted through the air.
Matching Gender
This word describes a noun. If the noun is feminine (like 'la enfermedad'), change the ending to -a: 'la enfermedad infecciosa'.
Word Order
In Spanish, words that describe something (like 'infeccioso') usually come AFTER the thing they are describing, not before it like in English.
Gender Mismatch
Mistake: “La bacteria es infeccioso.”
Correction: La bacteria es infecciosa. Use the 'a' ending because 'bacteria' is a feminine word.
Contagioso vs. Infeccioso
Related Translations
Learn Spanish with Inklingo
Interactive stories, personalized learning, and more.