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History:  36-year-old male with 7-days of fever, general malaise, diffuse myalgia, headache, and retro-orbital pain.  Three days prior to admission, there was 1 episode of hematemesis.  At the same time a rash developed on the upper extremities which by the time of admission extended to the thorax, abdomen, and finally to the lower extremities.  History of adequately treated pulmonary TB 10 years earlier, and a remote history of vivax malaria.

Epidemiology:  Born and currently lives in Chanchamayo, La Merced, Department of Junin, which is located in the central part of the country at an altitude of 775 meters above sea level in the cloud forest (high jungle).  He works in public transportation.  No history of recent travel.  Up-to-date on all routine vaccines including yellow fever.

Physical Examination:  No acute distress.  BP 110/70, HR 86, RR 20, T 37.2ºC.  HEENT: bilateral conjunctival injection.  No jaundice, no purpura.  Chest clear, cardiovascular normal.  Abdomen: soft, nontender.  No hepatosplenomegaly.  Skin: diffuse blanching erythematous rash [Image A].  CNS: alert and oriented.

Laboratory Tests:  Hematocrit 46, WBC 3.1, unremarkable differential.  Platelets 120,000.  Total bilirubin 0.9, AST 52, ALT 73.  Chest x-ray normal.

Dengue infections range from asymptomatic through a range of clinical manifestations to death.  The incubation period of this flavivirus is normally 3-7 days from the time of the infective bite of the Aedes mosquito and 14 days at the most.  Typical dengue fever is manifest by frontal headache, retro-orbital pain, muscle and joint pain, nausea, vomiting and rash.  Fever lasts 5-7 days and may be biphasic or saddleback but this is not the norm.  An early flushlike rash sometimes occurs and wanes after a few days and may be replaced by a macular or morbilliform rash such as is seen in this patient and also in an earlier case of the week.  The morbilliform rash is often described as white islands on a red sea.  A late petechial rash may also occur.  Virus may be isolated from blood during the first 5 days only.  IgM elevations don't occur until 5 days or more so a sample taken earlier may be negative.  Four-fold elevations of IgG on acute and convalescent serum may be required to confirm diagnosis.

A diagnosis cannot be made on clinical findings alone.  Malaria, other arboviruses, leptospirosis, rickettsial disease, measles, rubella, or typhoid may present similar findings in the pre-rash phase of infection and need to be tested for.  Mild elevations of liver function tests as found here are typical of dengue as well as the other diseases mentioned.  The morbilliform rash is similar to that found in rubella, which needs to be considered in inadequately immunized patients.  If symptoms begin more than 2 weeks after a patient has left an endemic area dengue can be essentially ruled out.

This patient had hematemesis but is not considered to have DHF.  Recognized WHO criteria for DHF must include all of 1) fever; 2) hemorrhagic manifestations (or a positive tourniquet test); 3) platelets less than 100K; and 4) one piece of evidence of increased plasma leakage (pleural effusion, ascites, hematocrit increased 20% over normal or drop of 20% with hydration, or hypoproteinemia).  Thrombocytopenia often occurs with uncomplicated dengue so that hemorrhage without plasma leakage does not constitute DHF.

Dengue was reported for the first time in Peru in 1990; since then, all four serotypes are circulating, mainly along the north coast and the jungle.  Lima was affected for the first time in 2005, with 200 cases of serotype 3 diagnosed in the northern suburban district of Comas.  The Aedes vector remains present in isolated areas of the city but no further human cases have occurred.

Approximately 5500 cases of classic dengue were reported to the Peruvian Ministry of Health during 2006; 24% less than in 2005.  In the past 3 months from December 2006, more than 700 cases of mostly type 3 have been reported, mainly from the jungle area where this patient is from and from the northern coastal departments of the country.

Our patient is recovering with only fluids and supportive care.  The rash is beginning to fade but is still very noticeable 6 days after admission.