MANILA - Davao City Mayor Sara Duterte and Senator Risa Hontiveros continued to trade barbs Wednesday after the latter called for the resignation of Public Attorney's Office chief Persida Rueda-Acosta.

Hontiveros earlier said Acosta's "politically-motivated" investigation into the previous administration's anti-dengue immunization drive eroded the public's trust in vaccines.

The Department of Health has declared measles outbreaks in 5 regions in the Philippines, and has recorded 70 deaths in the first 40 days of 2019.

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Acosta has led the filing of dozens of complaints against officials of the Aquino administration for distributing the dengue vaccine Dengvaxia, which its maker admitted could trigger more severe symptoms in some cases.

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Duterte, who is the daughter of President Rodrigo Duterte, has defended Acosta, saying she "is doing her job in assisting indigent litigants who want to sue."

"Ikaw (Hontiveros) dapat magresign dahil wala ka ng sinabi na tama. Lahat sablay," the mayor said on Instagram, where she has 379,000 followers.

"Mag isip po tayo ng solution, hindi opposition para lang may masabi," she added.

(Let's think of a solution, instead of opposition just for the sake of having something to say.)

The Davao mayor also said Dengvaxia should be blamed for lower public trust on vaccines. She added Hontiveros "can easily verify this if you talk to the people in barangays instead of putting your head inside your behind all the time."

Hontiveros, in a statement on Tuesday, said Acosta's resignation is "part of the solution" as this "would remove the pseudo-science, fear-mongering and lies that hijacked the Dengvaxia discourse."

She said her legislative track record "speaks for itself" and proceeded to enumerate measures that she backed, including the Mental Health Law, the Expanded Maternity Leave Law, the Strengthened Anti-hospital Deposit Law, and the Philippine HIV and AIDS Policy, among others.

Hontiveros also said every insult from President Rodrigo Duterte's daughter is "a reading on the barometer I can use, second to none, to confirm how effective my office is in advancing democratic interests and goals."

The senator said the last time the Davao mayor criticized her was due to her opposition of a proposal to bring down the minimum age of criminal liability.

Noting that a recent Social Weather Station (SWS) survey showed that the majority of Filipinos oppose the proposal, Hontiveros said: "How's that for a reality check? Pardon my French, but I’m not the one with my head in my ass."

'AN ATTACK IS AN ATTACK'

Duterte however said Hontiveros cannot use criticism as a validation of her work.

"Ai naku po, an attack is an attack. Don't use attack, validation and vindication in one sentence," she said in another Instagram post on Tuesday night.

"Otherwise, your attacks against the administration are validations to say that PRD (President Rodrigo Duterte) is correct and therefore he is vindicated. And you still believe your head is on your shoulders?" she added.

Hontiveros shot back that there is a difference between criticizing the President and his allies' criticism of the opposition.

"When we scrutinize the Pres & hold him to higher standards, it is to exact accountability. When they attack & insult us for doing so, they insist on their impunity," she said on Twitter early Wednesday.