8 items - S6 Table. 6. 3. Strength of association. Summary: Total 7 items in 2 groups reviewed. The reviewers ... Several states reported increases in 2015 vs. 2014 ...
S6 Table. Causality framework evidence for Zika virus infection and Guillain-Barré syndrome Contents S6 Table. Causality framework evidence for Zika virus infection and Guillain-Barré syndrome ........................................................................................................... 1 1.
Temporality ............................................................................................................................................................................................................................ 2
2.
Biological plausibility .............................................................................................................................................................................................................. 4
3.
Strength of association ........................................................................................................................................................................................................... 6
4.
Exclusion of alternative explanations ..................................................................................................................................................................................... 6
5.
Cessation ................................................................................................................................................................................................................................ 7
6.
Dose-response relationship .................................................................................................................................................................................................... 8
7.
Animal experiments................................................................................................................................................................................................................ 8
8.
Analogy ................................................................................................................................................................................................................................... 9
9.
Specificity.............................................................................................................................................................................................................................. 11
10.
Consistency ....................................................................................................................................................................................................................... 11
References ........................................................................................................................................................................................................................................ 13
1
S6 Table Question Causality dimension and no. question
Study type, Linked Country of study Support Do not Summary of evidence number of primary items causality support items [reference] dimension causality of included items dimension Summary: Total, 31 studies in 26 groups. Reviewer assessments found sufficient evidence for all 3 questions of an appropriate 1. Temporality temporal relationship between Zika virus (ZIKV) infection and Guillain-Barré syndrome (GBS). The time interval between ZIKV symptoms and onset of neurological symptoms was compatible with that of other accepted triggers of GBS. 1.1a Does ZIKV infection precede the Case report, 4 [121] Brazil, 9 0 The exposure was reported before the outcome in development of GBS in [110, 111, 117, linked to El Salvador, studies in Brazil, El Salvador, Panama, Puerto Rico, individuals? 120]; [120] Panama, Puerto Venezuela, in French Polynesia, and in returning Case series, 4 [105, [102, Rico, Venezuela, travellers: 106, 108]; 116] French Polynesia, The first case was reported during the 2013-14 ZIKV Case-control study, linked to United Statesa, outbreak in French Polynesia. An influenza-like illness 1 [112] [112] Netherlandsa occurred 7 days before the onset of GBS symptoms. ZIKV RT-PCR was negative on day 8. Serology on days 8 and 28 suggested recent ZIKV infection (IgM positive) and past dengue virus (DENV) infection (IgG positive) [102]; 83 of 112 patients (74%) with GBS reported ZIKVrelated symptoms before the onset of GBS symptoms, of which 53 cases (all except 42 cases in Brazil and all cases in El Salvador) were laboratory confirmed ZIKV infections [105, 106, 108, 110-112, 120]. 1.1b Is there a consistent timeEcological [103, Brazil, Colombia, 9 7 Studies at the population level report differing findings dependent relationship between study/outbreak 122] Dominican about the temporal relationship between reported the occurrence of ZIKV cases and report, 16 [55-57, linked to Republic, cases of Zika-like illness and GBS cases: cases with GBS at population67, 100, 104, 107, [104] El Salvador, In 9 countries (Brazil, Colombia, Dominican Republic, level? 109, 115] French Guiana, El Salvador, French Polynesia, Honduras, Paraguay, Haiti, Honduras, Suriname and Venezuela) an increase of GBS cases Martinique, was observed during the ZIKV epidemic [56, 57, 67, Panama, 104, 107, 109]. In Brazil, the number of cases Paraguay, Puerto recorded in 2015 was 19% higher than in the previous Rico, Suriname, year [57]; Venezuela, In Haiti, French Guiana, Federal States of Micronesia Micronesia, (Yap), Panama, Puerto Rico, and Martinique there
2
S6 Table French Polynesia, Pacific Islands
1.2
Is the interval between exposure Case report, 3 [102, Brazil, El to ZIKV and occurrence of [110, 111, 117]; 116] Salvador, symptoms typical for para- or Case series, 2 [106, linked to Panama, Puerto post-infectious GBS? 108]; [112] Rico, Venezuela, Case-control study, [102, French Polynesia 1 [112]; Ecological 116] study/outbreak linked report: 1 [78] to[112]
7
0
was no increase in GBS cases above the background level [55, 57, 67, 109] or no increase in hospitalisations during the epidemic [100] 1 study examined reports of acute flaccid paralysis (AFP) collected for polio surveillance in children in several Pacific Islands as a possible signal of GBS cases [115]. An increase above the expected annual number of AFP cases in the same year as a ZIKV outbreak was only seen in the Solomon Islands. In most islands the expected number of cases was
