Micro Case Study 2: Boy with fever and rash

[Anonymous]

Case Study 2
Boy with fever and rash
In early June a 15-year old boy comes to your practice with his mother. He had been fine until about five days ago when he developed a fever. He has a stiff neck and a rash on his back. He and his family live in Connecticut near the New York State border. His mother reports that he was playing in the woods with some friends recently.



Question 1 of 6
The diagnosis is?


A. Lyme Disease

B. Syphilis

C. Poison Ivy



ans in bold:
A. Lyme Disease


The patient's rash (erythema migrans) and his other symptoms, fever and a stiff neck, along with the geographic location suggest that the patient is suffering from Lyme disease. The rash is typically ring-shaped, centered on the site of inoculation, and expands and moves outward.
In the US most cases of Lyme disease are reported in the Northeast, the North-central states, and the West Coast. The rash usually appears 3 days to 1 months after infection on the thigh, groin, trunk or armpits. Other symptoms of the early stage of Lyme disease can include fatigue, headache, muscle and joint pain, and swollen lymphnodes.


B. Syphilis


Syphilis is a sexually transmitted disease caused by Treponema pallidum, a spiral-shaped bacterium. Syphilis can progress through four stages with dramatically different clinical presentations.


Used with permission of
© Dr. Norm Levine

Primary syphilis is characterized by a skin lesion at the initial site of entry of the infectious agent and usually occurs 2 - 10 weeks after infection. The patient's rash is on his back, this is a very unlikely port of entry for syphilis. Also the skin lesion in primary syphilis, referred to as chancre, looks quite different from the rash seen in your patient.

C. Poison Ivy

Contact with poison ivy can result in a skin rash and even fever depending on the individual's sensitivity. However, the onset of symptoms is typically 24-48 hours after exposure, your patient reported being in the woods 5 days ago. A rash from poison ivy is usually preceeded by severe itching, which was not reported by your patient. The rash caused by poison ivy is often characterized blistering of the skin unlike the rash observed in your patient.



Question 2 of 6
We established that the patient has Lyme disease.
Which of the following organism is he infected with?


A. Streptococcus pyogenes
B. Borrelia burgdorferi


C. Pseudomonas aeruginosa

D. Clostridium perfringens





ans in bold:
A.Streptococcus pyogenes
Infecions with Streptococcus pyogenes can result in a variety of conditions ranging from "strep throat", impetigo and scarlet fever to toxic-shock-like syndrome. However, Streptococcus pyogenes does not cause Lyme disease. Systemic infecions with Streptococcus pyogenes can result in skin lesions such as cellulitis, scarlet fever or necrotizing fasciitis. These are acute and often life-threatening infections, and the lesions differ from the rash observed in this patient.


B.Borrelia burgdorferi


Dark field microscopy
of B. burgdorferi

Borrelia burgdorferi is the causative agent of Lyme disease. This bacterium, just like Treponema pallidum, is a member of the spirochetes, the family of spiral-shaped bacteria. These bacteria can move with the help of "internal" flagella, or axial filaments, which are hidden between the bacterium's inner and outer membrane and result in a cork-screw like motion.


C.Pseudomonas aeruginosa
Pseudomonas aeruginosa is an opportunist which can cause skin lesions. Infections usually follow either damage to the skin or septicemia (in which the patient would be seriously ill). Infections with this organism do not result in Lyme disease.

D.Clostridium perfringens


Clostridium perfringens can cause anaerobic cellulitis and gas gangrene usually following profound tissue damage, and the resulting disease is severe and life-threatening. The lesions of gas gangrene are substantially different from the rash observed in this patient.



Question 3 of 6
How is Lyme disease usually transmitted?


A. Bite of infected tick
B. Contact with lesion of infected person

C. Ingestion of contaminated food

D. Introduction of contaminated soil in skin lesion



ans in bold:

A. Bite of infected tick

Female tick:
Ixodes dammini


Lyme diease is spread by the bite of ticks of the genus Ixodes infected with Borrelia burgdorferi. Ticks become infected with Lyme disease bacteria when they feed on infected animals (humans, mice). A recent survey showed that in the northeaster US (Massachusetts to Maryland) more than 20% of the ticks are infected with B. burgdorferi. Ticks drop on their host animals from vegetation. They cannot jump or fly but only crawl. People who frequent wooded, brushy, and grassy areas are most likely to get in contact with ticks. Ticks feed on blood by inserting their mouth parts into the skin of the host. This allows the bacterium to enter the skin of the human host and cause disease.

B. Contact with lesion of infected person

Spread of the disease by any route other than introduction of B. burgdorferi into the blood stream by an infected tick is highly unlikely. Borrelia burgdorferi is a very "fragile" organism. It requires specific conditions for it's growth and survival which are present in the tick or it's mammalian host (lower oxygen levels, many nutrients.)
C. Ingestion of contaminated food
Ingested bacteria would not survive the passage through the highly acidic stomach and the environment in the intestine is not suitable for growth.
D. Introduction of contaminated soil in skin lesion

Survival outside its hosts in soil or food is very short and spread of the disease by this route very unlikely



Question 4 of 6
Which other disease can be transmitted by infected ticks?


A. Rocky Mountain spotted fever
B. Legionnaire's Disease

C. Cholera

D. Plague



ans in bold:
A. Rocky Mountain spotted fever
Rocky Mountain spotted fever, a disease caused by Rickettsia rickettsii, is transmitted by wood ticks and dog ticks. Symptoms appear approximately one week after infection and include fever, headache, and a rash which usually appears 3 to 5 days later on the wrists and ankles, spreading to chest and abdomen. The greatest incidence is reported in the states Oklahoma, North and South Carolina, Arkansas, Georgia, and Virginia.
B. Legionnaire's Disease
Legionnaire's Disease, a bacterial pneumonia, is caused by an infection of the lung with Legionella pneumophila. Legionella is ubiquitous in soil and water and may grow in cooling towers of central air-conditioning systems. Infection usually occurs by inhalation of aerosolized bacteria from air-conditioning systems. The disease typically occurs in individuals with a compromised immune system (smoking, alkohol, old age) while healthy children and adults are relatively resistant.
C. Cholera
Cholera is caused by the ingestion of food or water contaminated with the feces of an infected individual. The causative agent is the bacterium Vibrio cholerae, which can grow in the intestines after ingestion and produces a toxin leading to massive diarrhea and fluid loss.
D. Plague
Plague can occur in two different clinical manifestations: bubonic plague and pneumonic plague. Bubonic plague is typically transmitted by infected fleas, not ticks. Yersinia pestis, the causative agent, enters the body of the victim as the flea is feeding. The bacteria are then transported to the local lymphnodes where they multiply and cause the characteristic swellings (bubo). Pneumonic plague can result when the bacteria spread from the lymphnodes via the blood stream to the lungs or directly by inhalation of aerosolized bacteria from a patient with pneumonic plague.






Question 5 of 6
Is Lyme disease a curable disease?

A.Yes
B.No




ans:
A. Yes
Lyme disease is a bacterial infection caused by Borrelia burgdorferi. The organism can be destroyed by certain antibiotics targeting components unique to bacterial cells (eg. tetracyclin, erythromycin). Lyme disease is typically treated with oral antibiotics under the supervision of a medical doctor over a period of at least 10 days. Nearly half the patients with Lyme disease have minor recurrences (eg headache, fatigue) but eventually recover completely.




Question 6 of 6
Why is it important to give patients with Lyme disease adequate treatment?

A. To prevent further spread of the disease
B. The patient can develop complications if untreated
(eg. cranial palsy, peripheral neuropathy, cardiac defects)
C. The rash can ulcerate if left untreated




ans in bold:
A. To prevent further spread of the disease
Treatment of an infected individual would not have much impact on the spread of the disease. The disease is spread by ticks infected by feeding on wild animals, such as white-footed mouse, white-tailed deer which are hosts for Borrelia burgdorferi.

B. The patient can develop complications if untreated
(eg. cranial palsy, peripheral neuropathy, cardiac defects)

Lyme disease often occurs in several stages separated by symptom-free periods. However, not every patient experiences all phases or symptoms.
Stage 1
Stage 1 begins 3 days to 1 month after infection and lasts for several weeks. It is characterized by the symptoms described by the patient: rash, headache, neck stiffness, fever, chills, severe headaches, joint and musculoskeletal pain, and fatigue.
Stage 2
If left untreated, stage 2 occurs after several weeks or months with meningits, musculoskeletal pain, and neurological abnormalities (encephalitis, cranial neuritis, facial palsy etc). A small number of patients also develops cardiac problems during this time. Neurologic symptoms usually disappear completely within months.
Stage 3
Within weeks to 2 years after onset of infection 60% of untreated patients develop arthritis with brief bouts of pain and swelling in joints (eg. knees). Many patients also suffer from fatigue.

The course of Lyme disease, caused by Borrelia burgdorferi, is very similar to that of Syphilis, caused by Treponema pallidum. Both bacteria are members of the same family, the spirochetes and both diseases occur in several stages: primary syphilis, like the primary stage of Lyme disease, is characterized by a skin lesion at the site of infection which disappears spontaneously. Secondary syphilis is characterized by fever and rash. Tertiary syphilis can occur years later and symptoms include heart damage, neurologic symptoms and fatigue.

C. The rash can ulcerate if left untreated
The rash (Erythema migrans) can expand to a large size and sometimes many patches appear which can vary in shape. The center of the lesion can sometimes become necrotic (with dead tissue). Even in untreated patients the early symptoms, including the rash, usually improve or disappear within several weeks. Therefore, the rash usually is not the major concern in Lyme disease.

[Anonymous]

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