A 21-year-old college student was admitted to the hospital in July with a fever of 40°C, dry cough, dyspnea and prostration of increasing severity over the past 24 hours.
He had been previously healthy and was spending his summer on Martha’s Vineyard as a groundskeeper for a golf course. He was living in a beach house with some college friends, with no pets in the house.
He did not use alcohol or tobacco and had no history of recent travel.
On admission he had crackles over both lung fields but no other abnormalities on physical examination.
Bilateral pneumonia was present on chest x-ray. WBC was 4,100 with a normal differential. Hemoglobin was 15 and platelets 150,000. His AST and ALT were 2 x normal.
He said his coworker at the golf course had been admitted with a similar illness the prior day to another hospital.
Among the possible inhalation exposures that must be considered in the management of this patient, which of these is the most likely?
A) Ticks or small rodents ground up by the lawn mower
B) Cleaning out rodent nests from under the tool shed
C) Scraping pigeon droppings off the patio
D)Scrubbing the shower floor at the swimming pool
E) Spreading compost on the flowers
Correct answer: Ticks or small rodents ground up by the lawn mower
The geography should suggest tularemia as more likely than some of the other options, especially Hantavirus pulmonary syndrome (rodent nests) that would be more likely in the Southwest. Tularemia is usually acquired from an infected small animal through cutaneous inoculation of the animal's blood into a small cut or from a tick bite. However, machines that cut grass and brush can aerosol tissue or ticks from infected animals and cause pulmonary tularemia. When there is aerosol exposure, pulmonary infiltrates are bilateral, the wbc is often normal, and the transaminases are often mildly elevated.
Diagnosis is usually made retrospectively by serology but effective treatment requires an aminoglycoside or perhaps a fluoroquinolone for more mild cases.
Rodent nests can be a source of Hantavirus pulmonary syndrome through the urine and feces. In this case there is no hemoconcentration, or biphasic illness, or geographic clue to make this the most likely diagnosis
Pigeon droppings can be found to contain Cryptococcus but rarely appear to trace to cases of cryptococcosis. Cryptococcal pneumonia in previously healthy persons is indolent and without many systemic symptoms.
Aerosolized water can be a source of Legionnaires' disease. The chance that both these employees inhaled contaminated water while scrubbing the shower floor seems remote. Legionnaires' is a less likely cause than tularemia.
Compost can lead to aspergillosis in patients with impaired immunity. Aspergillus does not cause invasive pulmonary disease in immunocompetent patients.
A 49-year-old male third grade school teacher with HIV infection complains of fatigue.
He was started 3 months ago on dolutegravir, tenofovir, and emtricitabine after presenting with CD4 count =75 cells/uL and viral load = 100,000. His hemoglobin was 13g/dl prior to therapy but is now 6g/dl.
Chemistries are unremarkable including liver function tests, haptoglobin and LDH.
He has no evidence of blood loss and has negative stool tests for occult blood.
He had a urinary tract infection last week and was started on ciprofloxacin. He also takes vitamin C. No one in his household has been ill, but some of the children in his class had been out last month with fever and facial rash.
Which of the following interventions is most likely to be beneficial for the most likely cause of this anemia?
A) Stop vitamin C
B) Initiate erythropoietin
C) Switch antiretroviral therapy from dolutegravir to efavirenz
D) Initiate corticosteroids
E) Initiate IVIG
Correct answer: Initiate IVIG.
This patient with pure red blood cell aplasia with no clear evidence for hemolysis or gastrointestinal blood loss likely has parvovirus B19 infection. Unlike the transient aplastic crisis seen in patients with increased erythropoiesis, immunosuppressed patients with parvo B19 infection develop chronic anemia. For diagnosis, PCR detection of viral DNA in blood is the best test. This patient’s serum PCR test for erythrovirus was positive. He presumably acquired this from children, and his job as a teacher of young children provided opportunity for exposure. Giant abnormal pronormoblasts on bone marrow biopsy, when present, are also diagnostic.
IgG and IgM antibody may be negative in a large fraction of HIV-infected patients. This viral infection is controlled in normal hosts by humoral immunity.
In this HIV-infected patient, Parvovirus B19 infection with red cell aplasia may improve with intravenous immunoglobulin (400 mg/kg/d for five days is effective in 75% of patients.) Patients may require a second course of IVIG and some patients may require a maintenance regimen of 30 g per month plus iron and folate and B12.
The anemia typically develops over a long period of time since the pathogenesis is suppression of erythropoesis.
Parvovirus B19 spreads primarily by respiratory route and has an incubation time of 4-14 days in immunocompetent children and young adults. Immunity is generally lifelong in immunologically normal patients following infection.
Keep in mind that parvovirus B 19 causes several types of disease:
- Normal Children: self-limiting fever with “slapped cheeks” followed by lacy body rash
- Healthy adults: asymptomatic or transient fever, occasionally small joint arthropathy plus rash that resolve in three weeks, especially in young women.
- Patients with an underlying hemolytic disease: Acute, transient aplastic crisis
- Pregnancy: Fetal death, hydrops fetalis
- Immunosuppressed: Chronic red cell aplasia
A 25-year-old male recently moved to a dilapidated apartment in the Upper East Side of Manhattan to take a job as a sports teacher in a New York City public elementary school. The children in his second grade class were largely poor, including many recent immigrants. After a month at his new job, he developed low-grade fever and a tender red papule in his right axilla which became vesicular and then with a black and necrotic center.
He didn’t seek medical attention because his health insurance had a waiting period before becoming effective. He continued teaching because the school couldn’t find a substitute.
On the third day of illness, red papular lesions appeared on his trunk.
When seen in the Emergency Department, he appeared only mildly ill, with a fever of 38.5°C, had approximately 20 papular lesions with a vesicular center on his trunk, a dark brown healing lesion in the right axilla, and a 2 cm soft axillary node in the site.
His CBC and platelet count were normal except for a WBC of 3,800 with a normal differential.
The most likely source of the illness was which of the following?
A) Body louse from one of his students
B) Mice in his apartment building
C) New sexual partner
D) Student with chickenpox
E) Tick bite from petting a neighbor’s dog
Correct answer: Mice in his apartment building
The presence of an eschar followed in 3 to 5 days by papular and vesicular lesions is typical of Rickettsia akari infections, rickettsialpox.
New York City has several dozen cases of rickettsialpox per year, transmitted by bites from a mouse mite.
The illness is rarely severe.
Doxycycline 200 mg per day for a week is advised but spontaneous recovery is usual.
The other answers don’t include diseases with an eschar and vesicular rash. Louse-borne typhus, not seen in the USA, and tick-borne rickettsial infections cause a maculopapular rash.
Tache noire (eschar) and rash for a patient with Rickettsial pox (Emerging Infections July 2002)