Since the Zika outbreak dispersed in the Americas, public health authorities have stated that only about one out of five people infected with the virus Zika develops any symptoms.
However, experts are doubting this standard assumption with a fear that it may understate the actual percentage of people who can become ill. According to virologist Mauricio Lacerda Nogueira of the Sao Jose de Rio Preto medical school in Sao Paulo, the reality of an outbreak on a small island cannot reflect that in a big nation with various types of people, climates and other conditions, so that they have to recalculate “that number”.
It’s an important question to authorities in Brazil and other places in order to measure the true extent and effect of the outbreak associated with a rise in the microcephaly birth defect cases. Knowing the actual ratio of people who develop symptoms could help public health officials make a better preparation for future outbreaks of this dangerous virus.
Medical experts had a reason to believe the widely cited ratio might not be precise because the study was done “in one place at one time”, according to epidemiologist Marc Fischer, of the U.S. Centers for Disease Control and Prevention (CDC).
Fischer and other experts said the current outbreak, which has evoked a global health scare, could result in a different assessment of the percentage of people infected with the virus end up being ill.
Because it’s believed that people who have already been infected generate immunity to Zika, the accurate ratio of infection during this epidemic could help doctors calculate how many of them might remain susceptible if those patients get sick again.
Much remains still vague about Zika, including whether the virus actually causes microcephaly, a disease that makes a baby’s head smaller than usual; and whether it can lead to developmental problems. Brazil has stated that it has confirmed 508 cases of microcephaly in babies believed to have followed Zika infections. The nation is observing more than 3,900 other cases.
In the study, blood samples of 557 random residents were taken to estimate the ratio which is a single symptomatic person out of 4.4 people who showed laboratory signs of having been infected with Zika but no signs of illness. But the ratio on Yap Island also could have been affected by Zika antibodies which could be confused with those of similar infections, like dengue, the disease previously infected some islanders, according to Fischer of CDC. Yap Island has a population of just 7,000 people while other sites of the outbreak, like Brazil, have a far bigger and denser population. So, without better measurements, the actual number of Zika infections could remain elusive.
Brazilian officials are making clinical diagnoses for most patients primarily based on symptoms. Plus, pregnant women and people showing signs of neurological complications are having to use costly and time-consuming genetic testing, which is available only at some laboratories and is possible only during a period of less than a week when patients exhibit symptoms.
Without quicker and more affordable testing, it’s been estimated by Brazil’s health ministry that 1.5 million people may have been infected up to now.