Lategan was part of the squad in Dubai, Cape Town and Perth and on stand-by for the North American leg of the series.
Tsiremba injured her ankle in the team's last match against Great Britain in Vancouver on Sunday, and has been ruled out of the LA tournament.
The Bok Women will face New Zealand, crowned champions in Canada, in their opening match at Dignity Health Sports Park in the early hours on Saturday morning (SA time) and will face Fiji later in the day. They will also have a third consecutive outing against Brazil in their final pool match on Sunday.
South Africa faced New Zealand in Dubai and Vancouver, with the Kiwi side winning 19-14 and 35-5 respectively. The Bok Women have only faced Fiji once so far, also in Dubai, losing 21-17.
Their clashes against Brazil were also close encounters. They lost 7-0 in Perth and 17-12 in Vancouver.
Springbok Women's Sevens pool schedule (SA times):
Saturday 2 March
03h36: New Zealand
22h26: Fiji
Sunday 3 March
03h02: Brazil