query: SELECT DISTINCT ?item ?itemLabel ?_PubMed_ID
  WHERE
  {
    ?item wdt:P31 wd:Q13442814 ;
          rdfs:label ?itemLabel .
    OPTIONAL { ?item wdt:P698 ?_PubMed_ID. }
    FILTER(CONTAINS(LCASE(?itemLabel), "zika"))
    FILTER (LANG(?itemLabel)="en")
  }