Zika Virus in Brazil: Ground Zero of the 2015–16 Epidemic

Brazil was the epicenter of the world's largest Zika epidemic, producing thousands of cases of Congenital Zika Syndrome and prompting the 2016 WHO PHEIC.

The 2015–2016 Brazilian Zika Epidemic

Zika virus likely entered Brazil through French Polynesia tourists attending the 2014 FIFA World Cup, or through the 2014 Va'a World Sprint Championship in Rio de Janeiro. The virus spread rapidly through Brazil's dense urban Aedes aegypti mosquito populations.

By late 2015, Brazilian doctors noticed an alarming surge in babies born with microcephaly — abnormally small heads — in northeastern states like Pernambuco. Investigation confirmed Zika as the cause. Over 1.5 million Brazilians were infected in 2015–2016, and an estimated 3,000–4,000 babies were born with Congenital Zika Syndrome (CZS).

Key Statistics

Long-term Impact on CZS Children

The children born with CZS in 2015–2016 are now approaching 10 years old. Long-term follow-up studies from Brazil have documented a broader spectrum of disability than initially recognized:

• Epilepsy in majority of severely affected children
• Profound intellectual disability across the CZS spectrum
• Feeding difficulties requiring gastrostomy in many children
• Progressive spasticity and joint contractures
• Vision and hearing impairment
• Children with apparently normal head size at birth developing neurological problems in later childhood

Families — predominantly from poor northeastern communities — face enormous caregiving burdens with inadequate specialist care, few therapists, and limited social support. The Brazilian government's cash transfer program (Benefício de Prestação Continuada) provides some financial support to most affected families.

Sources: Brazil Ministry of Health Zika/microcephaly reports; NEJM CZS characterization (Mlakar et al. 2016); Lancet Brasil et al. pregnancy outcomes; WHO PHEIC documentation.

Related: Zika overview · Zika pregnancy risks · 2016 Zika Americas outbreak