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During the past week the Gorgas Course in Clinical Tropical Medicine concluded with a 4-day field trip to Iquitos on the banks of the Amazon River.  Iquitos, with a population of approximately 500,000, is the largest city in the world that is reachable only by air and by river.  The nearest road ends over 400 km away.

Publishing a case report every Monday for 9 consecutive weeks would not be possible without the assistance of an extremely dedicated group of people.  We would like to thank in particular: Dr. Carlos Seas, Clinical Rounds Coordinator for the Gorgas Courses for case selection, coordination of case summaries and images; Drs. Jaime Cok and Juan Ferrufino for preparation and discussion of pathologic specimens; Mrs. Carmen Castro for microbiology and Dr. Ramiro Vilcahuaman for radiology; and Adam Plier of the UAB Division of Geographic Medicine for all publishing on the Gorgas Course web site.

We hope you have enjoyed this year?s cases.  In August 2006 we will be running the 2-week Gorgas Expert Course and will present a couple more cases during that time.  We will also be in touch in January 2007 at the beginning of next year?s case series.

The following patient was seen on the Obstetrics ward at the Iquitos Hospital.

History: 22 yo female with onset of fever, malaise, and pruritic skin lesions seven days earlier.  The lesions began on her abdomen and spread over subsequent days to her chest, face, and then extremities.  Several mouth lesions have now resolved.  Fresh lesions are still appearing.  She is 25 weeks into her first pregnancy.  No previous medical problems.  No cough, dyspnea, or shortness of breath.

Epidemiology: Lifelong resident of Iquitos. Three younger siblings living at home developed a similar febrile rash illness in the 2 weeks prior to illness onset.

Physical Examination: Afebrile at time of admission.  Chest clear.  No lymphadenopathy or hepatosplenomegaly.  Oral mucosa clear.  Diffuse skin lesions with earliest lesions on face [Image A], chest lesions [Image B], and close-up of an extremity lesion in Image C.

Laboratory Examination: Hct 40. WBC 7.0. Malaria smear negative.

Discussion: Acute Varicella Zoster Virus (VZV) infection is a clinical diagnosis with a characteristic (see Images A-C) vesicular rash of the superficial dermis involving the trunk, face, and oropharynx.  Notably, several crops of fresh vesicles may erupt every few days, becoming crusted and lasting for a total of 6-10 days.  In contrast, the lesions of smallpox [Image D] begin on the extremities with all lesions occurring at the same time and appearing and evolving in a similar manner.  The incubation period of varicella is 10-21 days, most commonly about 14 days.  One of our patient?s siblings had been exposed, while visiting a neighbor, to a young child with varicella.

In the tropics, including in developing countries, the age distribution of acute varicella differs markedly from that in temperate climates.  Only the minority of individuals acquire varicella in childhood, so that many adults remain non-immune and clinical varicella in adults is common.  In temperate climates only 2% of varicella cases occur in those over 20 years of age.  In the US and Europe, varicella outbreaks in immigrant and refugee communities are increasingly frequent events.  The reasons for the altered behavior of VZV virus in the tropics have not been elucidated.

Complications of varicella are more common in adults, especially varicella pneumonia. which occurs in up to 20% of adult cases.  Pneumonia in pregnant women is more severe though perhaps not more frequent than in other adults.  Pneumonia usually develops in the first week of rash onset and pregnant women should be followed closely for the onset of respiratory symptoms.

The risk of congenital varicella infection is relatively low ranging from 0.4% in the first trimester to about 2.0% in babies of mothers infected at 13-20 weeks and negligible risk after that.  Manifestations of congenital varicella are usually relatively mild with chorioretinitis, optic atrophy, pigmented patches of skin but may include hypoplastic limbs, club feet, cataracts, micropthalmos and early death.

Neonatal varicella is a serious illness with a 25% mortality rate due to disseminated infection and visceral involvement.  Women who become clinically ill with varicella from 4 days before delivery until 2 days after delivery may transmit VZV during delivery.  Babies of such women should receive Varicella zoster immune globulin (VZIG) intramuscularly immediately after birth.

While the use of acyclovir for acute varicella infection in immunocompetent women has not been rigorously evaluated, most clinicians would use it (safe in pregnancy) to hasten the healing of skin lesions, decrease the severity of maternal disease and reduce the chance of complications which may be more severe during pregnancy.  Seronegative pregnant women who are exposed to varicella zoster should receive VZIG for up to 96 hours after exposure, but VZIG is not indicated in an active case.