#10,988
Yesterday, in Guillain-Barre syndrome: The Other Zika Concern, we looked at the suspected - but as yet unproven - link between the recent arrival of Zika to the Americas and French Polynesia and reports of a concurrent rise in cases of Guillain-Barré Syndrome.
Along the way we also looked at previous outbreaks and individual cases of GBS that have been attributed to a variety of causes, including some linked to arboviral infections like Dengue and Chikungunya.
In early 2014 in Zika, Dengue & Unusual Rates Of Guillain Barre Syndrome In French Polynesia we got our first clue that something unexpected was going on with Zika, and over the past couple of months we've seen reports of increased GBS in Brazil, Colombia, El Salvador, Suriname, and Venezuela - all countries where Zika has recently arrived.
Complicating matters, Zika isn't the only arbovirus circulating in these countries. Dengue has been around for decades, but Chikungunya only began to spread widely in the Americas in early 2014.
Many of those who are now falling victim to Zika have previously had CHKV and/or Dengue (I-4), raising questions over the potential impact of concurrent or sequential infection.
And trying to compare the rates of GBS from previous years - when surveillance and reporting may not have been particularly thorough - to today, when doctors are actively looking for cases, can produce misleading numbers.
Still - just as with microcephaly in Brazil - something seems to be driving the rates of GBS substantially higher these seven countries. And right now Zika - or perhaps Zika combined another factor - is at the top of the suspect list.
The World Health Organization published two GBS updates overnight, with the first - from Martinique - of particular interest because it describes two recent Guillain-Barré cases, both of whom have tested positive for the Zika virus.
The update from Brazil describes major increases in GBS in some states, but stable rates (or even declines) in others, leaving us with an incomplete, and muddled picture. As with the apparent increases in microcephalic births, there are still more questions than answers.
Guillain-Barré syndrome – France - Martinique
On 25 January 2016, the National IHR Focal Point of France notified PAHO/WHO of 2 cases of Guillain-Barré Syndrome (GBS) in Martinique.
Details of the cases
- The first case is a 19-year-old with onset of symptoms (paraesthesia of hands and feet) on 26 December. Urine samples, which were taken on 7 January, tested positive for Zika virus by reverse transcription polymerase chain reaction (RT-PCR) at the University Hospital of Martinique. Currently, the patient is being intubated and ventilated in an intensive care unit.
- The second case is a 55-year-old who was admitted to an intensive care unit on 21 January. On the same day, urine samples were collected from the patient. The samples tested positive for Zika virus by RT-PCR at the University Hospital of Martinique. Currently, the patient is being ventilated because of his respiratory failure.
WHO risk assessment
At present, available information is insufficient to interpret the observed differences in GBS incidence globally and among Brazilian states. The potential cause of the reported increase of GBS incidence in certain Brazilian states remains unknown. Case-control studies are ongoing to determine the cause of the increase. These studies may provide evidence that corroborates or disproves a causal relationship between Zika virus, GBS and other congenital malformations. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information.
WHO recommends Member States affected or susceptible to Zika virus outbreaks to:
- monitor the incidence and trends of neurological disorders, especially GBS, to identify variations against their expected baseline values;
- develop and implement sufficient patient management protocols to manage the additional burden on health care facilities generated by a sudden increase in patients with Guillain-Barre Syndrome;
- raise awareness among health care workers and establish and/or strengthen links between public health services and clinicians in the public and private sectors.
WHO advice
The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for Zika virus infection. Prevention and control relies on reducing the breeding of mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people. This can be achieved by reducing the number of natural and artificial water-filled habitats that support mosquito larvae, reducing the adult mosquito populations around at-risk communities and by using barriers such as insect screens, closed doors and windows, long clothing and repellents. Since the Aedes mosquitoes (the primary vector for transmission) are day-biting mosquitoes, it is recommended that those who sleep during the daytime, particularly young children, the sick or elderly, should rest under mosquito nets (bed nets), treated with or without insecticide to provide protection.
During outbreaks, space spraying of insecticides may be carried out following the technical orientation provided by WHO to kill flying mosquitoes. Suitable insecticides (recommended by the WHO Pesticide Evaluation Scheme) may also be used as larvicides to treat relatively large water containers, when this is technically indicated.
Basic precautions for protection from mosquito bites should be taken by people traveling to high risk areas, especially pregnant women. These include use of repellents, wearing light colored, long sleeved shirts and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering.
WHO does not recommend any travel or trade restriction to France and the overseas departments of France based on the current information available.
Guillain-Barré syndrome – Brazil
On 22 January 2016, the National IHR Focal Point of Brazil notified PAHO/WHO of an increase of Guillain-Barre Syndrome (GBS) recorded at the national level.
Data from the hospital-based surveillance system reveal that, between January and November 2015, 1,708 cases of GBS were registered nationwide. While a number of states reported significant increases in reported cases – especially, Alagoas (516.7%), Bahia (196.1%), Rio Grande do Norte (108.7%), Piauí (108.3%), Espirito Santo (78.6%), and Rio de Janeiro (60.9%) – other states reported stable or even diminishing number of GBS cases as compared to 2014. Most of the states in Brazil are experiencing the circulation of Zika, chikungunya, and dengue virus.
WHO risk assessment
At present, available information is insufficient to interpret the observed differences in GBS incidence globally and among Brazilian states. The potential cause of the reported increase of GBS incidence in certain Brazilian states remains unknown. Case-control studies are ongoing to determine the cause of the increase. These studies may provide evidence that corroborates or disproves a causal relationship between Zika virus, GBS and other congenital malformations. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information.
