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8. Viral diseases
Dengue fever
– D engue fever is an arthro p o d -bo rne viral d isease transm itted to m an thro ugh the bite
o f the Aedes m o squito . It d evelo p s sp o rad ically and / o r as ep id em ics (so utheast
A sia,
the P acific, A frica, the C aribbean and S o uth and C entral A m erica). F o ur d ifferent
sero ty p es o f d engue virus exist.
– cPlarsimsicaarlydeinnfgeucteiofenvewri.thA thseedcoenngdueinfveircutisomn wayithbae dasifyfemrenpt stoermo taytipc oe rmmaayypprorevsoenkt easdengu
haemorrhagic fever, characterised by an increased vascular p erm eability with lo ss o f
p lasm a fro m the vascular co m p artm ent and haem o co ncentratio n.
– D engue haem o rrhagic fever m ay p ro gress to dengue shock syndrome if, at the end o f
the febrile p erio d , a significant p lasm a lo ss is no t well co m p ensated .
Clinical features
– Dengue fever
• fever with head ache, retro -o rbital p ain, m uscle and jo int p ain
• m aculo p ap ular rash o n the lo wer lim bs
• ctoesmt )manodnmanodreberanrigenlyh, amemuco rsrahla(geipc sisigtanxsi:s,skgining(ivpael btelecehdiainego) r p o sitive to urniquet
1
– Dengue haemorrhagic fever
• h igh fever ( 3 9 °C - 4 1 °C ) o f sud d en o nset lasting 2 to 7 d ay s ( so m etim es w ith
2 p eak s)
• hteasetm) ; mo rurhcoaguics smigenms: bskrainne(sp( eptecishtaiaxeis,,pgiunrgpivuarlab,leecdchinygm) ; goassetrso, pintoesstiitnivael ttroacutrniquet
1
(haem atem esis, m elaena); bleed ing fro m venep uncture sites
•8hep ato m egaly
– Dengue shock syndrome
The critical stage is at the end o f the febrile p erio d (fro m D ay 3 to D ay 7 ). The signs
p reced ing sh o ck are: p ersistent vo m iting, intense abd o m inal p ain, agitatio n o r
lethargy , sud d en hy p o therm ia. A scites o r p leural effusio n are p o ssible.
S igns o f sho ck :
• rap id and weak , then und etectable p ulse
• co ld extrem ities, p ro fuse sweating
• narro w p ulse p ressure, hy p o tensio n
Grading severity of dengue haemorrhagic fever (from WHO)
Grade test and / o r easy bruising) Clinical features
I F ever + no n-sp ecific general sy m p to m s + haem o rrhagic signs (p o sitive to urniquet
1
II G rad e I m anifestatio ns + sp o ntaneo us bleed ing (sk in o r o ther haem o rrhages)
III C irculato ry failure
ToIVurniqPuertotefsot: uinnfldateshaoblcokodwpirtehsusunrdeectuefcf toanbtlheepupuplseer aarnmdtoblaopooindt mp idrewsasyubreetween the systolic and diastolic
1
pressure for 5 minutes. The test is considered positive when 20 or more petechiae per 2.5 cm square are observed.
201
Dengue fever
– D engue fever is an arthro p o d -bo rne viral d isease transm itted to m an thro ugh the bite
o f the Aedes m o squito . It d evelo p s sp o rad ically and / o r as ep id em ics (so utheast
A sia,
the P acific, A frica, the C aribbean and S o uth and C entral A m erica). F o ur d ifferent
sero ty p es o f d engue virus exist.
– cPlarsimsicaarlydeinnfgeucteiofenvewri.thA thseedcoenngdueinfveircutisomn wayithbae dasifyfemrenpt stoermo taytipc oe rmmaayypprorevsoenkt easdengu
haemorrhagic fever, characterised by an increased vascular p erm eability with lo ss o f
p lasm a fro m the vascular co m p artm ent and haem o co ncentratio n.
– D engue haem o rrhagic fever m ay p ro gress to dengue shock syndrome if, at the end o f
the febrile p erio d , a significant p lasm a lo ss is no t well co m p ensated .
Clinical features
– Dengue fever
• fever with head ache, retro -o rbital p ain, m uscle and jo int p ain
• m aculo p ap ular rash o n the lo wer lim bs
• ctoesmt )manodnmanodreberanrigenlyh, amemuco rsrahla(geipc sisigtanxsi:s,skgining(ivpael btelecehdiainego) r p o sitive to urniquet
1
– Dengue haemorrhagic fever
• h igh fever ( 3 9 °C - 4 1 °C ) o f sud d en o nset lasting 2 to 7 d ay s ( so m etim es w ith
2 p eak s)
• hteasetm) ; mo rurhcoaguics smigenms: bskrainne(sp( eptecishtaiaxeis,,pgiunrgpivuarlab,leecdchinygm) ; goassetrso, pintoesstiitnivael ttroacutrniquet
1
(haem atem esis, m elaena); bleed ing fro m venep uncture sites
•8hep ato m egaly
– Dengue shock syndrome
The critical stage is at the end o f the febrile p erio d (fro m D ay 3 to D ay 7 ). The signs
p reced ing sh o ck are: p ersistent vo m iting, intense abd o m inal p ain, agitatio n o r
lethargy , sud d en hy p o therm ia. A scites o r p leural effusio n are p o ssible.
S igns o f sho ck :
• rap id and weak , then und etectable p ulse
• co ld extrem ities, p ro fuse sweating
• narro w p ulse p ressure, hy p o tensio n
Grading severity of dengue haemorrhagic fever (from WHO)
Grade test and / o r easy bruising) Clinical features
I F ever + no n-sp ecific general sy m p to m s + haem o rrhagic signs (p o sitive to urniquet
1
II G rad e I m anifestatio ns + sp o ntaneo us bleed ing (sk in o r o ther haem o rrhages)
III C irculato ry failure
ToIVurniqPuertotefsot: uinnfldateshaoblcokodwpirtehsusunrdeectuefcf toanbtlheepupuplseer aarnmdtoblaopooindt mp idrewsasyubreetween the systolic and diastolic
1
pressure for 5 minutes. The test is considered positive when 20 or more petechiae per 2.5 cm square are observed.
201
