Verbseoul.
하다 verb
만연하다manyeonhadato spread, to pervade, to grow rampant, to become rife (with)

To say to spread, to pervade, to grow rampant, to become rife (with) politely in the present tense, use 만연해요 (mah-nyuhn-hae-yoh). Below is the full conjugation of 만연하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
만연해
mah-nyuhn-hae
만연해요
mah-nyuhn-hae-yoh
만연합니다
mah-nyuhn-hahm-nee-dah
Past
만연했어
mah-nyuhn-hae-ssuh
만연했어요
mah-nyuhn-hae-ssuh-yoh
만연했습니다
mah-nyuhn-hae-sseum-nee-dah
Future
만연할 거야
mah-nyuhn-hahl- -guh-yah
만연할 거예요
mah-nyuhn-hahl- -guh-yae-yoh
만연할 겁니다
mah-nyuhn-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
만연하세요
mah-nyuhn-hah-sae-yoh
Suggestion / Let's Polite (요)
만연해요
mah-nyuhn-hae-yoh
Question Polite (요)
만연해요?
mah-nyuhn-hae-yoh-?
Connective “and” — (고)
만연하고
mah-nyuhn-hah-goh
Conditional “if” — (면)
만연하면
mah-nyuhn-hah-myuhn
Noun form — (기)
만연함
mah-nyuhn-hahm