( ( Dengue fever ) ( ( is ( caused ( by ( viruses ( that ( are ( carried ( by mosquitoes ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Dengue) (NN fever)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (NNS viruses)) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (VP (VBN carried) (PP (IN by) (NP (NNS mosquitoes))))))))))) (. .)))
Dengue fever is caused by viruses that are carried by mosquitoes.
(ROOT (S (NP (NP (JJ Dengue) (NN fever)) (CC and) (NP (JJ yellow) (NN fever))) (VP (VBP are) (NP (NP (NNS examples)) (PP (IN of) (NP (NP (NNS diseases)) (VP (VBN caused) (PP (IN by) (NP (NN virus)))))))) (. .)))