Wolbachia infection in a male mosquito who fertilises the eggs of a female without the bacteria, results in the production of eggs which do not hatch . If both male and female, or only the female mosquito are infected wit Wolbachia, all future generations of mosquito will carry this bacteria. This is illustrated in the figure below from http://www.eliminatedengue.com/our-research/wolbachia. Thus, after a while mosquitoes with Wolbachia become predominant without release of more mosquitoes being necessary.
Some studies show that these Wolbachia-infected mosquitoes also do not carry the chikungunya virus, so this strategy may end up reducing the incidence of both viral fever diseases in Brazil and other places where this Wolbachia-infected mosquito release strategy may be implemented- currently this program is also taking place in Australia, Vietnam and Indonesia.