The still poorly understood Zika virus outbreak across Brazil took a turn in the wrong direction this week. Local public health authorities announced that, in addition to severe birth defects, the infection may be linked to a paralytic condition called Guillain-Barré Syndrome, or GBS.

Unlike the birth defect microcephaly, which previously had not been associated with Zika virus, the connection between GBS and Zika already has been established. This condition, which most famously affected Catch-22 author Joseph Heller, is seen in a variety of situations. Many viral and bacterial infections may trigger the disease, as well as several vaccines.

With GBS, a person typically will lose strength in the legs at first; for some, the problem progresses in an “ascending” manner, meaning that the arms and the muscles of breathing may be next affected. Thankfully, for most patients, this severe form does not develop. If a patient—even one with paralyzed breathing muscles—can be stabilized, including support with a ventilator if needed, most will survive.

The impact of Zika virus, therefore, will be even more catastrophic than first feared a few weeks ago when the possible connection between infection during pregnancy and severe birth defects caught the world’s attention. Since then, infection and microcephaly have been seen in many additional countries, including an American who had lived in Brazil. The CDC has issued an unprecedented warning about travel for women who are pregnant or considering becoming pregnant.

In the terse dispatch from Jan. 15, 2016, entitled “CDC issues interim travel guidance related to Zika virus for 14 Countries and Territories in Central and South America and the Caribbean,” the CDC counseled pregnant women to consider delaying travel to affected areas and those who are trying to become pregnant to “consult their doctor.”

To the untrained eye, this may sound like typical CDC speak with advice leaking out of both sides of the mouth. But to the trained eye, this is screaming news declaring, “Oh, shit, this is bad!” though suavely hidden in the boring syllables. The CDC does not issue travel guidance affecting the economy of a large important country without some pretty scary fears growing deep in their overly-rational hearts.

The odd part about the situation, though, remains the inability to confirm without doubt the association between Zika and microcephaly. As mentioned, the paralysis from Zika is not a surprise given a previous observation from other Zika outbreaks and the settled fact that this can happen after an array of viral infections, including some from close genetic cousins of Zika.

In contrast, the possible link with birth defects and specifically microcephaly is unprecedented. There surely are infections that cause severe birth defects—rubella (German measles) may cause deafness; toxoplasmosis may cause blindness and other neurologic problems; congenital syphilis has a hundred different manifestations. But a new virus causing a rare nightmarish birth defect simply has not been seen with any of the recent waves of comparably frightening and lethal new outbreaks—not HIV, not SARS, not Ebola, not chikungunya.

From what we have been told, the virus has been found in many, but not all, of the infants born with the condition and the number of mothers of babies with microcephaly is reportedly “high.” But the lack of real data is altogether puzzling. With Ebola, we had daily dispatches of case-rates and movement from here to there. A few cases of polio in Ukraine prompted appropriate warning. The first case of seasonal flu is trumpeted with fear and trembling.

Yet right now, we still are trying to establish terra firma for the scope and severity of the outbreak. The always financially strapped World Health Organization (WHO) and Pan-American Health Organization (PAHO) have begun to provide solid no-nonsense information and surely will take the lead going forward.

The need to fully define the dimensions of the disaster is particularly pressing for Brazil. Mardi Gras, which is something of a Rapture-like event for the millions who attend, is weeks away. And more ominous yet, the Summer Olympics take place in Brazil starting in August. A mad scientist evil doer could concoct no more perfect scenario than gathering people from every country in the world to a country with an ongoing outbreak of a new virus, have them hang out for two or three weeks together, then return to their homes, infected. The only saving grace that thwarts the plan for world domination is that Zika is not transmitted person to person (though sexual transmission is a theoretical possibility).

Even as causation remains uncertain, what is increasingly clear is that the world, once again, is altogether unprepared for epidemic infection. Ebola was a tragic example of way too little way too late; SARS was an example of how difficult it can be to control an infection you don’t understand. And Zika is showing us how difficult it is to stop an outbreak when we don’t have the resources in place to even count cases reliably.

Hopefully, this tragedy will lead to better funding of public health programs in every country worldwide, but I wouldn’t count on it.

The CDC just sent out two additional reports on the status of the Zika outbreak. In the first, “Zika Virus Spreads to New Areas—Region of the Americas, May 2015—January 2016,” they detail the scope of the epidemic among all adults, stating that 440,000 to 1.3 million cases occurred in Brazil, a country of about 200 million people, last year. Globally, cases from the current outbreak in adults have been reported from 20 countries and territories. The CDC also notes that about 80 percent of all cases appear to occur without symptoms and that hospitalization and death from the infection are quite rare.

The second report, “Possible Association Between Zika Virus Infection and Microcephaly—Brazil, 2015," updated information on the association between maternal infection and microcephaly. The CDC is conducting an in-depth examination of 35 infants with microcephaly. For 74 percent, mothers recalled a rash during first or second trimester and all resided in Zika-endemic areas. Most infants had severe microcephaly. Virologic studies for the infants, including analysis of spinal fluid, is pending. Importantly, the CDC continues to almost-but-not-quite declare a cause-and-effect relationship between infection and microcephaly. It is likely that the pending results from the spinal fluid is a crucial piece of information.