The Holy Father has not, to my knowledge, released a position on the Zika crisis in Brazil; much less on the experimental use of GM mosquitoes to fight it. The Brazilian Bishops' Conference, on the other hand, released a statement (reported in a Brazilian Catholic news site, in Portuguese) on the Zika crisis, mentioning the need to "wage war" on the mosquito.
They have not publicly commented on the GM mosquito plan, but no bishop has spoken out against it, either.
Here is a translation of the note:
MESSAGE FROM CNBB ON THE FIGHT AGAINST AEDES AEGYPTI
“so wilt thou recover me, and make me to live.” (Is 38:16b)
The Pastoral Episcopal Council (CONSEP), from the National Bishops' Conference of Brazil — CNBB, gathered together in Brasília–DF, in the 3rd and 4th days of February 2016, calls upon the whole of the Church in Brazil to continue and intensify her mobilization to combat the mosquito Aedes aegypti, agent for Dengue fever, Zika and Chikungunya virus. With a great collective effort, which involves all sectors of society, we will be able to defeat these diseases that affect, without distinction, the entire Brazilian population.
The Zika virus deserves special attention due to its probable link to microcephaly, although this has not yet been proven scientifically. The fravity of the situation has caused the World Health Organization to declare the microcephaly and the Zika virus international emergencies. The state of alert, however, must not lead us into panic, as if we were facing an invincible situation, in spite of its extreme gravity. Neither does it justify defending abortion for the microcephaly cases as, unfortunately, is the proposal of certain groups which are organising to take the issue before the Supreme Federal Tribunal in complete disrespect of the gift of life.
Let it be guaranteed, urgently, the assistance to those afflicted with these infirmities, particularly to the children who are born with microcephaly and their families. Health, God's gift and everyone's right, must be assured, in the first place, by public administrators. To them falls the implementation of policies which point to a public health system which both is universal and has good quality. In this direction, the Ecumenical Fraternity Campaign for this year contributes a good deal by bringing up the shameful reality of basic sanitation in Brazil. Without an effective national policy for basic sanitation, the whole effort in combatting Aedes aegypti is compromised.
The commitment of each citizen is also essential to the task of eradicating this evil which defies our institutions. The principle of everything is education and co-responsibility. For that reason, we exhort the leaderships of our ecclesial communities to organise actions which add to the initiatives which intend to put an end to this situation. The actions for which the public sector is responsibe should be demanded and their progress must be accompanied. In celebrations and meetings, may clear and objective orientations be given so as to help people to become conscious of the gravity of the situation and also of the best way to fight these diseases and their agent. With everyone's effort, victory shall not elude us.
May God, in His infinite mercy, make health spread through all the Earth (cf. Sir 38:8). May Our Lady of Aparecida, mother and patroness of Brazil, help us in our evangelic commitment to promote and defend life.
Brasília, 4 February 2016
Dom Sergio da Rocha
Archbishop of Brasília-DF
President of CNBB
Dom Murilo S. R. Krieger
Archbishop of São Salvador da Bahia-BA
Vice-presidente of CNBB
Dom Leonardo Ulrich Steiner
Auxiliary Bishop of Brasília-DF
Secretary-General of CNBB