Severe respiratory failure may require insertion of a tube into the trachea (intubation) to assist the child's breathing until the infection is brought under control.

CNN: Bronchiolitis

After the operation, a government spokesman said Chavez was battling a severe lung infection that caused respiratory failure.

CNN: Venezuela says Chavez is improving

Last week, a government spokesman said Chavez was battling a severe lung infection that has caused respiratory failure.

CNN: Venezuela's Chavez is not in a coma, his brother says

All three died after suffering severe respiratory symptoms, including acute respiratory distress syndrome and eventually septic shock and multiple organ failure.

CNN: New bird flu well-adapted to infect people