Health officials in Uruguay, meanwhile, reported three new cases of the A(H1N1) virus Sunday, bringing the total there to 25.
Nicaragua's health minister Guillermo Gonzalez said cases of the illness are "appearing because we are actively looking for them," explaining the uptick in the disease first detected here just seven days ago.
The latest rash of cases prompted brigades of health workers to descend on some 20,000 homes in a Managua neighborhood where the outbreak was spotted.
Gonzalez said the majority of cases have been detected in people who visited countries where the disease has taken a firmer hold.
The virus has largely hit school-aged children, prompting the temporary closure of at least two schools.
Meanwhile, Argentina's 13 new cases bring the total number of cases there to 215, according to health officials, who said three-quarters of confirmed cases have been in school-aged children.
Officials in Buenos Aires said they are reviewing more than 800 suspected cases of the ailment.