"Later, in 1982, a local outbreak of Issyk-Kul fever occurred in Qumsangir district (Khalton Province, Tajikistan). During the outbreak, 22 cases were registered. For 17 patients, antibody titers increased (from 1:8-1:16 to 1:32-1:256) (2, 3). The patients with confirmed increased antibody titers were registered: one in March, two in April, one in May, four in June, four in July and five in August of 1982."
Do you really need "confirmed"? If not, delete it.
It's customary to write whole numbers below 10 in words.
Are the 17 cases a subset of the 22 cases? If so, you could shorten this some more by saying:
"Later, in 1982, a local outbreak of Issyk-Kul fever occurred in Qumsangir district (Khalton Province, Tajikistan). During the outbreak, 22 cases were registered. These included 17 patients whose antibody titers increased (from 1:8-1:16 to 1:32-1:256) (2, 3), registered in March (one), April (two), May (one), June (four), July (four) and August (five)."