Situation summary
Autochthonous transmission of Zika virus From February 20141 to 17 January 2016, there are 18 countries and territories in the Americas that have confirmed autochthonous circulation of Zika virus (ZIKV) in 2015 and 2016: Brazil, Barbados, Colombia, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, and Venezuela. Between November 2015 and January 2016, local transmission of the virus was detected in 14 new countries and territories.
Increase in neurological syndromes
Guillain'Barré Syndrome
During the Zika virus outbreak in French Polynesia (2013-2014), 274 patients had presented neurological syndromes or auto-immune syndromes after the manifestation of symptoms consistent with Zika virus infection. Of these, 42 were classified as Guillain`Barré syndrome (GBS). Of the 42 registered SGB, 24 (57%) were male, and 37 (88%) had signs and symptoms consistent with Zika virus infection (3, 4, 5).
In July 2015, Brazil reported the detection of patients with neurological syndromes who had recent history of Zika virus infection in the state of Bahia. There were 76 patients with neurological syndromes identified, of which 42 (55%) were confirmed as GBS. Among the confirmed GBS, 26 (62%) had a history of symptoms consistent with Zika virus infection.
In addition, on 25 November 2015, the Aggeu Magalhães Research Center of the Oswaldo Cruz Foundation reported that ZIKV infection was found in 10 of the 224 suspected dengue patients whose samples were analyzed for Zika virus infection. Seven of the 10 samples analyzed corresponded to patients with neurological syndrome.
In January 2016, El Salvador reported the detection of an unusual increase of GBS since early December 2015. On average, El Salvador records14 cases of GBS per month (169 cases per year), however, between 1 December 2015 and 6 January 2016 there were 46 GBS recorded, of which 2 died. Twenty`five (54%) were male and 35 (76%) were over 30 years old. All were hospitalized and treated with plasmapheresis or immunoglobulin. Of the deceased patients, one had a history of multiple underlying chronic diseases. In 22 patients whose information was available 12 (54%) had febrile rash illness between 7 and 15 days prior to the onset of GBS.
Currently, similar situations are being investigated in other countries of the Americas. These findings are consistent with a temporal and spatial link between Zika virus circulation and the increase of GBS. Although the etiopathogenesis and associated risk factors have not yet been well established, Member States should implement surveillance systems to detect unusual increases in cases and prepare health services for patients care with neurological conditions.
Other neurological syndromes
Zika virus can cause other neurological syndromes (meningitis, meningoencephalitis and myelitis), as described in French Polynesia outbreak (2013`2014). While in the Region of the Americas such syndromes have not been reported so far, health services and practitioners should be alert about their possible occurrence to properly prepare health facilities for rapid detection and appropriate treatment of cases.
Increase in microcephaly and other congenital anomalies
In October 2015, the Brazil International Health Regulations (IHR) National Focal Point (NFP) notified the detection of an unusual increase in microcephaly3 cases in public and private healthcare facilities in Pernambuco state, Northeast Brazil. 4 As of epidemiological week 1 of 2016, there were 3,530 microcephaly cases recorded, including 46 deaths, in 20 states and the Federal District. Between 2010 and 2014, an average of 163 (Standard deviation 16.9) microcephaly cases was recorded nationwide per year.5 Figure 1 shows the comparative distribution of microcephaly case (annual average between 2010 and 2014 compared with cases registered in 2015).
In January 2016, ophthalmological findings were reported in three children with microcephaly and cerebral calcifications detected by CT scans and presumable intrauterine ZIKV infection. The three infants had unilateral ocular findings involving the macular region and loss of foveal reflex. In one child a well defined macular neuroretinal atrophy was detected (6).
Evidence of vertical transmission of Zika virus
On 13 January 2016, the Brazil Ministry of Health reported the detection of Zika virus genome, through the RT-PCR technique in four cases of congenital malformation in the state of Rio Grande do Norte. The cases correspond to two miscarriages and two at full-term newborns (37 and 42 weeks respectively) who died in the first 24 hours of life. Tissue samples from both newborns were also positive for Zika virus by immunohistochemistry (1).
This adds to the evidence reported in the Epidemiological Alert of 1 December 2015 with respect to the detection of Zika virus genome through RT-PCR technique in the amniotic fluid of two pregnant women in Paraiba, whose fetuses presented with microcephaly according to the ultrasound (7).