Jeff Koterba cartoon for January 29, 2016 “Zika Ebola Health Mosquito”
In February, The Scientist reported on a review of four years’ worth of medical records by Brazil’s Círculo do Coração de Pernambuco, which found far greater numbers of microcephaly cases from before the ongoing Zika virus epidemic than had been officially reported. Some have questioned whether the cause of this increase in microcephaly is due to Zika virus, other infections, or simply a catch-up in reporting.
Sandra da Silva Mattos of the Círculo do Coração de Pernambuco and colleagues combed through the medical records of more than 16,000 babies. The infants were born between 2012 and 2015 at one of 21 medical centers in the state of Paraíba, which has been hard hit by Zika.
Since 2012, Mattos’s team found, a strikingly large number of babies—4 percent to 8 percent—appeared to have microcephaly, according to the broadest definitions of the term. Additionally, the number of babies affected peaked in 2014, before Zika had been detected in Brazil.
“What we expected was that we would have something like three to four cases a year of microcephaly—that is what has been documented in the official sites,” Mattos told ABC. “But we then noticed that we had much, much higher numbers.”
When the researchers narrowed the definition to only the most extreme cases of microcephaly, the rates (0.04 percent to 1.9 percent) were more in line with those reported elsewhere in the world. But this still meant hundreds of babies had microcephaly. In contrast, the nationwide incidence of microcephaly reported in years before 2015 was below 200 annually.
“It is possible that a high incidence of milder forms microcephaly has been occurring well before the current outbreak, but that only those extreme cases, with classical phenotypes, were being notified,” the authors wrote in their report, published (February 4) in the Bulletin of the World Health Organization. “And as the number of extreme cases increased over these past three or four months so did the awareness of health professionals who started to notify milder forms.”
Their report notes: “If the ZIKV were indeed introduced in Brazil at the World Cup in mid 2014, the outbreak of microcephaly would have preceded it. ZIKV has been identified in Africa over 50 years ago, and neither there nor in the outbreaks outside Africa, such an association with microcephaly has been reported.”
“Many other potential factors need to be considered as the cause of the outbreak. Among the figures the possibility of boosting effects from associated infections, perhaps even viral infections, such as DENV and CHIKV, both carried by the same Aedes aegypti vector. Also to be considered is teratogens exposure, such as vaccines or drugs used in early pregnancy. Further, malnutrition, which has previously been associated to microcephaly, could have an intensifying effect when coupled with other aetiological factors. Indeed, most of the reported cases have occurred in low-income families.”
Jorge Lopez-Camelo and Ieda Maria Orioli, from the Latin American Collaborative Study of Congenital Malformations, also suggest that the surge might largely be attributed to the intense search for cases of the birth defect, and misdiagnoses, because of heightened awareness in the wake of the possible link with Zika. They say that from the epidemiological data available, it is impossible to establish the true size of the surge in microcephaly.
A February 5 article in The Lancet also brought up the need to standardize diagnostic criteria for microcephaly. “Although there is evidence of an increased number of cases of microcephaly in Brazil, we show that the number of suspected cases relied on a screening test that had very low specificity and therefore overestimated the actual number of cases by including mostly normal children with small heads,” wrote researchers from the Federal University of Pelotas, Brazil, and their colleagues.
Most people infected with the Zika virus — after being bitten by a mosquito — have no symptoms; the remainder have mild symptoms such as fever, skin rash and headache.
And remember how just two months ago a Zika vaccine was supposedly at least 18 months away. What a surprise to hear that “human trials will start in America soon,” reported Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. Dr Fauci said the American vaccine would focus on pregnant women, and women of childbearing age, with a longer-term goal of offering a vaccine to everyone, particularly if that link to microcephaly is confirmed.
A Nature article noted: The rate of Zika infections may drop off over time, because most people who are infected will probably develop immunity to Zika and thus cannot become reinfected. But even then, “we’ll probably need a routine vaccination to control the infection”, says Alexander Precioso, director of the clinical trials and pharmacovigilance division of the Butantan Institute in São Paulo, Brazil.
Microcephaly usually is the result of abnormal brain development, which can occur in the womb or during infancy. Causes include: Decreased oxygen to the fetal brain. Infections of the fetus during pregnancy – These include toxoplasmosis, cytomegalovirus, German measles (rubella) and chickenpox (varicella). Exposure to drugs, alcohol, certain toxic chemicals and heavy metals like arsenic and mercury in the womb. Severe malnutrition – Not getting adequate nutrition during pregnancy can affect development.