Pathfinder
Editor, Senior Moderator
ZIKA VIRUS
MICROCEPHALY
AND GUILLAIN-BARR? SYNDROME
SITUATION REPORT
26 FEBURARY 2016
SUMMARY
Between 1 January 2007 and 25 February 2016, a total of 52 countries and territories
have reported autochthonous (local) transmission of Zika virus, including those where
the outbreak is now over and countries and territories that provided indirect evidence of
local transmission. Among the 52 countries and territories, Marshall Islands, Saint
Vincent and the Grenadines, and Trinidad and Tobago are the latest to report
autochthonous transmission of Zika virus.
The geographical distribution of Zika virus has steadily widened since the virus was first
detected in the Americas in 2015. Autochthonous Zika virus transmission has been
reported in 31 countries and territories of this region. Zika virus is likely to be transmitted
and detected in other countries within the geographical range of competent mosquito
vectors, especially Aedes aegypti.
So far an increase in microcephaly cases and other neonatal malformations have only
been reported in Brazil and French Polynesia, although two cases linked to a stay in Brazil
were detected in two other countries.
During 2015 and 2016, eight countries and territories have reported an increased
incidence of Guillain-Barr? syndrome (GBS) and/or laboratory confirmation of a Zika virus
infection among GBS cases.
Evidence that neurological disorders, including microcephaly and GBS, are linked to Zika
virus infection remains circumstantial, but a growing body of clinical and epidemiological
data points towards a causal role for Zika virus.
The global prevention and control strategy launched by WHO as a Strategic Response
Framework1 encompasses surveillance, response activities and research, and this
situation report is organized under those headings. Following consultation with partners
and taking changes in caseload into account, the framework will be updated at the end of
March 2016 to reflect epidemiological evidence coming to light and the evolving division
of roles and responsibilities for tackling this emergency.
I. SURVEILLANCE
Incidence of Zika virus
From 1 January 2007 to 25 February 2016, Zika virus transmission was documented in a
total of 52 countries and territories (Fig. 1 and Fig. 2). This includes 40 countries that
reported autochthonous transmission between 2015 and 2016, six countries with indirect
evidence of viral circulation, five countries with reported terminated outbreaks and one
country with a locally acquired infection in the absence of any known mosquito vectors
(United States of America; Table 1).
Figure 1: Cumulative number of countries, territories and areas reporting Zika virus transmission,
2007-2014, and monthly from 1 January 2015 to 25 February 2016.
Towards the end of 2014, Brazil detected a cluster of cases of febrile rash in the
Northeast Region of the country. The diagnosis of Zika virus infection was confirmed (RTPCR
test for viral RNA2
) in May 2015. The Brazilian Ministry of Health estimates that there
were 0.4-1.3 million cases of Zika virus infection in 2015, many more than were reported
or confirmed.3
Recently the virus has spread rapidly across the region. By 25 February 2016, 31
countries and territories in the Americas had reported local transmission of the virus. The
reported rate of its spread across South and Central America accelerated from October
2015 onwards (Fig. 1, Table 1).
...
From 1 October 2015 to 13 February 2016, Colombia reported 37 011 cases, including
1612 laboratory confirmed cases of Zika virus infection.
5
From 2007, locally acquired Zika cases have been reported in 14 countries and territories
in the Western Pacific Region. Four Pacific Island countries and areas (American Samoa,
Marshall Islands, Samoa and Tonga) have reported Zika infections in 2016. Nauru has
declared Zika virus as a national emergency of concern for purposes of preparedness, but
to date no ZIKV cases have been reported.
From 1 October 2015 to 7 February 2016, Cabo Verde (African region), reported 7325
suspected cases of Zika virus disease. The outbreak peaked during the last week of
November 2015 and has been on a steady decline since then; 67 cases were reported in
the week up to 7 February 2016. Preliminary information, subject to confirmation,
indicates that this outbreak has been caused by an African strain of Zika virus. No
neurological abnormalities have been reported.
Incidence of microcephaly
Between 22 October 2015 and 20 February 2016 a total of 5640 cases of microcephaly
and/or central nervous system (CNS) malformation have been reported by Brazil
including 120 deaths. This contrasts with the period from 2001 to 2014, when an
average of 163 microcephaly cases was recorded nationwide per year
The reported increase in microcephaly incidence in Brazil is concentrated in the
Northeast Region (Fig. 3).
Of the 5640 suspected cases of microcephaly reported in Brazil, investigations have been
concluded for 1533 cases. Among these cases, 950 were discarded (i.e. not fulfilling the
operational case definition of microcephaly and/or CNS malformation associated with
congenital infection), 583 were confirmed and 4107 remain under investigation (Table
2).8 9
Among the 5640 suspected cases of microcephaly and/or CNS malformation, 120 child
deaths occurred after birth or during pregnancy (miscarriage or stillbirth); 30 of these
were confirmed as having microcephaly and/or CNS malformation potentially linked to
congenital Zika virus infection, 80 remain under investigation and 10 were discarded.
An outbreak of Zika virus in French Polynesia was followed by an increase in the number
of CNS malformations in children born between March 2014 and May 2015. 18 cases
were reported including nine microcephaly cases compared to the national average of 0-
2 cases per year.
Zika virus is not proven to be a cause of the increased incidence of microcephaly in
Brazil. However, given the temporal and geographical associations between Zika virus
infections and microcephaly, and in the absence of a compelling alternative hypothesis,
a causal role for Zika virus is a strong possibility that is under investigation.
Incidence of Guillain-Barr? syndrome (GBS)
In the context of Zika virus circulation eight countries or territories have reported
increased GBS incidence and/or laboratory confirmation of a Zika virus infection among
GBS cases (Table 3, Fig. 3).
In 2015, 42 GBS cases were reported, among which 26 (62%) had a history of symptoms
consistent with Zika virus infection in the state of Bahia in Brazil. A total of 1708 cases of
GBS were registered nationwide, representing a 19% increase from the previous year
(1439 cases of GBS in 2014), though not all states reported an increase in incidence.
Colombia reported an increase in the incidence of GBS as 201 GBS cases with history of
suspected Zika virus infection were reported in the nine weeks to 14 February. Most of
the cases are from Norte de Santander and Barranquilla ? areas where many of the Zika
virus cases have been registered. To date, none of these cases have been laboratory
confirmed for Zika virus infection, or other possible causes.
El Salvador recorded 118 GBS cases from 1 December 2015 to 8 January 2016, including
five deaths, while the annual average number of GBS cases is 169. To date, none of
those reported GBS cases have been laboratory confirmed for Zika virus infection or
other causes.
On 29 January 2016, Suriname reported an increased incidence of GBS: 10 GBS cases
reported in 2015 and three GBS cases were reported during the first three weeks of
2016, while Suriname registers on average approximately four cases GBS per year. For
two of the GBS cases reported in 2015 a Zika virus infection was laboratory confirmed by
RT-PCR.
Venezuela has also reported an increased incidence of GBS. From 1 January to 31
January 2016, 252 cases of GBS suspected to be related to Zika virus were reported. The
largest number of cases (66) was reported from six municipalities of Zulia state, mostly
concentrated in the Maracaibo municipality. Zika virus was confirmed in a three of the
GBS cases by RT-PCR.
GBS cases with laboratory confirmed Zika virus infections were reported from
Martinique (two cases) and Puerto Rico (one case).
In French Polynesia, 42 GBS cases were identified during the 2013 - 2014 Zika outbreak,
88% of those reported an illness compatible with Zika infection. Retrospective analysis
(seroneutralisation test) demonstrated that all 42 cases were positive for dengue and
Zika virus infection.
As with microcephaly, Zika virus is not proven to be a cause of increased GBS incidence
in Brazil, Colombia, El Salvador, Suriname or Venezuela. However, a causal role for Zika
virus is a strong possibility. Confounding factors include the contemporary circulation of
dengue and chikungunya in the Americas, which are transmitted by the same species of
mosquito. Further investigations are needed to identify the potential role of other
factors (including infections) known to be associated, or potentially associated, with
GBS.
...
Full report:
http://apps.who.int/iris/bitstream/10665/204491/1/zikasitrep_26Feb2016_eng.pdf
MICROCEPHALY
AND GUILLAIN-BARR? SYNDROME
SITUATION REPORT
26 FEBURARY 2016
SUMMARY
Between 1 January 2007 and 25 February 2016, a total of 52 countries and territories
have reported autochthonous (local) transmission of Zika virus, including those where
the outbreak is now over and countries and territories that provided indirect evidence of
local transmission. Among the 52 countries and territories, Marshall Islands, Saint
Vincent and the Grenadines, and Trinidad and Tobago are the latest to report
autochthonous transmission of Zika virus.
The geographical distribution of Zika virus has steadily widened since the virus was first
detected in the Americas in 2015. Autochthonous Zika virus transmission has been
reported in 31 countries and territories of this region. Zika virus is likely to be transmitted
and detected in other countries within the geographical range of competent mosquito
vectors, especially Aedes aegypti.
So far an increase in microcephaly cases and other neonatal malformations have only
been reported in Brazil and French Polynesia, although two cases linked to a stay in Brazil
were detected in two other countries.
During 2015 and 2016, eight countries and territories have reported an increased
incidence of Guillain-Barr? syndrome (GBS) and/or laboratory confirmation of a Zika virus
infection among GBS cases.
Evidence that neurological disorders, including microcephaly and GBS, are linked to Zika
virus infection remains circumstantial, but a growing body of clinical and epidemiological
data points towards a causal role for Zika virus.
The global prevention and control strategy launched by WHO as a Strategic Response
Framework1 encompasses surveillance, response activities and research, and this
situation report is organized under those headings. Following consultation with partners
and taking changes in caseload into account, the framework will be updated at the end of
March 2016 to reflect epidemiological evidence coming to light and the evolving division
of roles and responsibilities for tackling this emergency.
I. SURVEILLANCE
Incidence of Zika virus
From 1 January 2007 to 25 February 2016, Zika virus transmission was documented in a
total of 52 countries and territories (Fig. 1 and Fig. 2). This includes 40 countries that
reported autochthonous transmission between 2015 and 2016, six countries with indirect
evidence of viral circulation, five countries with reported terminated outbreaks and one
country with a locally acquired infection in the absence of any known mosquito vectors
(United States of America; Table 1).
Figure 1: Cumulative number of countries, territories and areas reporting Zika virus transmission,
2007-2014, and monthly from 1 January 2015 to 25 February 2016.
Towards the end of 2014, Brazil detected a cluster of cases of febrile rash in the
Northeast Region of the country. The diagnosis of Zika virus infection was confirmed (RTPCR
test for viral RNA2
) in May 2015. The Brazilian Ministry of Health estimates that there
were 0.4-1.3 million cases of Zika virus infection in 2015, many more than were reported
or confirmed.3
Recently the virus has spread rapidly across the region. By 25 February 2016, 31
countries and territories in the Americas had reported local transmission of the virus. The
reported rate of its spread across South and Central America accelerated from October
2015 onwards (Fig. 1, Table 1).
...
From 1 October 2015 to 13 February 2016, Colombia reported 37 011 cases, including
1612 laboratory confirmed cases of Zika virus infection.
5
From 2007, locally acquired Zika cases have been reported in 14 countries and territories
in the Western Pacific Region. Four Pacific Island countries and areas (American Samoa,
Marshall Islands, Samoa and Tonga) have reported Zika infections in 2016. Nauru has
declared Zika virus as a national emergency of concern for purposes of preparedness, but
to date no ZIKV cases have been reported.
From 1 October 2015 to 7 February 2016, Cabo Verde (African region), reported 7325
suspected cases of Zika virus disease. The outbreak peaked during the last week of
November 2015 and has been on a steady decline since then; 67 cases were reported in
the week up to 7 February 2016. Preliminary information, subject to confirmation,
indicates that this outbreak has been caused by an African strain of Zika virus. No
neurological abnormalities have been reported.
Incidence of microcephaly
Between 22 October 2015 and 20 February 2016 a total of 5640 cases of microcephaly
and/or central nervous system (CNS) malformation have been reported by Brazil
including 120 deaths. This contrasts with the period from 2001 to 2014, when an
average of 163 microcephaly cases was recorded nationwide per year
The reported increase in microcephaly incidence in Brazil is concentrated in the
Northeast Region (Fig. 3).
Of the 5640 suspected cases of microcephaly reported in Brazil, investigations have been
concluded for 1533 cases. Among these cases, 950 were discarded (i.e. not fulfilling the
operational case definition of microcephaly and/or CNS malformation associated with
congenital infection), 583 were confirmed and 4107 remain under investigation (Table
2).8 9
Among the 5640 suspected cases of microcephaly and/or CNS malformation, 120 child
deaths occurred after birth or during pregnancy (miscarriage or stillbirth); 30 of these
were confirmed as having microcephaly and/or CNS malformation potentially linked to
congenital Zika virus infection, 80 remain under investigation and 10 were discarded.
An outbreak of Zika virus in French Polynesia was followed by an increase in the number
of CNS malformations in children born between March 2014 and May 2015. 18 cases
were reported including nine microcephaly cases compared to the national average of 0-
2 cases per year.
Zika virus is not proven to be a cause of the increased incidence of microcephaly in
Brazil. However, given the temporal and geographical associations between Zika virus
infections and microcephaly, and in the absence of a compelling alternative hypothesis,
a causal role for Zika virus is a strong possibility that is under investigation.
Incidence of Guillain-Barr? syndrome (GBS)
In the context of Zika virus circulation eight countries or territories have reported
increased GBS incidence and/or laboratory confirmation of a Zika virus infection among
GBS cases (Table 3, Fig. 3).
In 2015, 42 GBS cases were reported, among which 26 (62%) had a history of symptoms
consistent with Zika virus infection in the state of Bahia in Brazil. A total of 1708 cases of
GBS were registered nationwide, representing a 19% increase from the previous year
(1439 cases of GBS in 2014), though not all states reported an increase in incidence.
Colombia reported an increase in the incidence of GBS as 201 GBS cases with history of
suspected Zika virus infection were reported in the nine weeks to 14 February. Most of
the cases are from Norte de Santander and Barranquilla ? areas where many of the Zika
virus cases have been registered. To date, none of these cases have been laboratory
confirmed for Zika virus infection, or other possible causes.
El Salvador recorded 118 GBS cases from 1 December 2015 to 8 January 2016, including
five deaths, while the annual average number of GBS cases is 169. To date, none of
those reported GBS cases have been laboratory confirmed for Zika virus infection or
other causes.
On 29 January 2016, Suriname reported an increased incidence of GBS: 10 GBS cases
reported in 2015 and three GBS cases were reported during the first three weeks of
2016, while Suriname registers on average approximately four cases GBS per year. For
two of the GBS cases reported in 2015 a Zika virus infection was laboratory confirmed by
RT-PCR.
Venezuela has also reported an increased incidence of GBS. From 1 January to 31
January 2016, 252 cases of GBS suspected to be related to Zika virus were reported. The
largest number of cases (66) was reported from six municipalities of Zulia state, mostly
concentrated in the Maracaibo municipality. Zika virus was confirmed in a three of the
GBS cases by RT-PCR.
GBS cases with laboratory confirmed Zika virus infections were reported from
Martinique (two cases) and Puerto Rico (one case).
In French Polynesia, 42 GBS cases were identified during the 2013 - 2014 Zika outbreak,
88% of those reported an illness compatible with Zika infection. Retrospective analysis
(seroneutralisation test) demonstrated that all 42 cases were positive for dengue and
Zika virus infection.
As with microcephaly, Zika virus is not proven to be a cause of increased GBS incidence
in Brazil, Colombia, El Salvador, Suriname or Venezuela. However, a causal role for Zika
virus is a strong possibility. Confounding factors include the contemporary circulation of
dengue and chikungunya in the Americas, which are transmitted by the same species of
mosquito. Further investigations are needed to identify the potential role of other
factors (including infections) known to be associated, or potentially associated, with
GBS.
...
Full report:
http://apps.who.int/iris/bitstream/10665/204491/1/zikasitrep_26Feb2016_eng.pdf