BIO-226 case studies (CH 23)

A 24-year-old traveler returns from sub-Saharan Africa and develops episodes of high fever accompanied by intense chills and sweating. The episodes seem to occur at regular intervals. A blood smear reveals a single-celled parasite inside red blood cells. The patient reports being bitten repeatedly by mosquitoes during the trip.

What is the disease + its causative agent?

Malaria

plasmodium spp.

A 67-year-old man develops fatigue, fever, chills, headache, muscle aches, and unusually dark urine approximately three weeks after hiking in an area heavily populated by deer. A blood smear reveals a parasite infecting and destroying red blood cells. He also complains of shortness of breath and says that he feels as though he "can't get enough air."

What is the disease + its causative agent?

Babesiosis

babesia microti

A rancher develops recurring episodes of fever, chills, heavy sweating, malaise, and fatigue. His fever becomes extremely high in the evening before subsiding and then returning again. He frequently consumes unpasteurized milk from his cattle.

Blood cultures reveal a Gram-negative rod that is catalase positive and capable of growing inside phagocytes.

What is the disease + its causative agent?

brucellosis

bruciella spp.

A 12-year-old girl develops a skin lesion several weeks after being bitten by an insect while traveling in South America. The lesion begins as a papule and nodule before progressing into a crusted ulcer. Several nearby lymph nodes become swollen.What is the disease + its causative agent?

Viral Leishmaniasis

leishmania spp.

A 35-year-old man who lived in rural South America as a child develops cardiac problems. He experiences an irregular heartbeat and eventually develops an enlarged heart and congestive heart failure.

He also develops severe constipation and an enlarged colon. His physician explains that these complications can occur 10–20 years after the initial infection.

What is the disease + its causative agent?

Chagas disease

A 31-year-old woman presents with sudden fever, chills, headache, weakness, and painful swelling of the lymph nodes in her groin. Several days earlier, she noticed a small insect bite after camping near an area inhabited by rats and ground squirrels.

The swollen lymph nodes become extremely painful and develop into large masses. Without treatment, the condition can progress rapidly and become fatal.

What is the disease + its causative agent?

Plague

yersinia pestis

A 28-year-old man develops fever, chills, headache, exhaustion, and swollen, painful lymph nodes approximately one week after being bitten by a deer fly. A skin ulcer has formed at the site of the bite.

He reports that he had been handling a dead rabbit shortly before becoming ill.

What is the disease + its causative agent?

Tularemia

Tularensis

A patient develops an abrupt fever of approximately 105°F, severe headache, chills, muscle and joint pain, and rose-colored spots on the skin. After several days, the fever disappears and the patient feels better.

Five days later, the high fever suddenly returns.

This cycle repeats several times.

What is the disease + its causative agent?

Relapsing fever

A 22-year-old woman from North Carolina develops a sudden high fever and severe headache approximately one week after removing a tick from her leg. Several days later, a rash develops on her palms and soles before spreading toward the trunk and extremities.

The physician immediately begins treatment because delaying treatment until the rash appears can be dangerous.

What is the disease + its causative agent?

Rocky Mountain spotted fever

rickettsia rickettsii

A man living in severely overcrowded and unsanitary conditions develops an abrupt, prolonged high fever approximately two weeks after becoming infested with body lice. He develops severe headache, fatigue, stupor, and a rash consisting of small spots primarily involving the chest, back, and trunk.

What is the disease + its causative agent?

Epidemic typhus

A patient living in a warm coastal region develops fever, headache, and a rash after exposure to rodents and opossums. The symptoms resemble another louse-borne illness, but the patient's illness is considerably milder and less likely to be fatal.

A rat flea is suspected to have transmitted the pathogen.

What is the disease + its causative agent?

Endemic murine typhus

A 29-year-old hiker notices a circular rash resembling a bull's-eye approximately two weeks after removing a tick. The rash is neither painful nor itchy.

Several weeks later, the rash disappears, but the patient develops fatigue, fever, an irregular heartbeat, and neurological problems.

Months later, the patient develops arthritis and facial paralysis.

What is the disease + its causative agent?

Lyme’s disease

Borrelia burgdorferi

A 10-year-old child develops fever and painful swelling of several large joints a few weeks after recovering from an inadequately treated sore throat.

The child subsequently develops a new heart murmur and chest pain. The physician also notices involuntary, jerky movements of the child's arms and legs.

What is the disease + its causative agent?

Rheumatic fever

Streptococcus pyogenes

A 19-year-old college student is bitten by a rat. Three days later, he develops a sudden high fever, headache, and severe muscle aches. The bite site is inflamed, and several lymph nodes become swollen.

A few days later, a rash develops particularly on the hands and feet.

Blood culture grows a Gram-negative rod.

What is the disease + its causative agent?

Rat-bite fever

streptobacillus monoliformis

A 9-year-old child develops a small papule at the site of a cat scratch. About two weeks later, the lymph nodes near the scratch become enlarged and painful. The child develops a low-grade fever and malaise.

The physician suspects a Gram-negative rod commonly carried by cats.

What is the disease + its causative agent?

Cat-scratch fever

bartonella hensellae

A 20-year-old college student develops extreme fatigue, fever, sore throat, and markedly swollen lymph nodes in the neck. Examination reveals white patches on the tonsils.

The physician warns the patient to avoid activities that could injure the abdomen because an internal organ may become enlarged.

A blood test detects antibodies against a human herpesvirus.

What is the disease + its causative agent?

Mononucleosis

HHV-4

A pregnant woman contracts a virus that commonly causes either no symptoms or a mild illness resembling mononucleosis. The pathogen can cross the placenta and infect the developing fetus.

The newborn later develops hearing problems and neurological impairment.

The virus remains latent in white blood cells and produces characteristic inclusion bodies in infected cells.

What is the disease + its causative agent?

Cytomegalovirus

HHV-5

A 26-year-old traveler develops sudden fever, chills, severe headache, back pain, muscle aches, nausea, and vomiting approximately five days after being bitten by a mosquito in a tropical region.

Several days later, the patient's skin and eyes become yellow, and laboratory testing indicates severe liver involvement.

What is the disease + its causative agent?

Yellow fever

arbovirus

A 23-year-old traveler develops a sudden high fever approximately one week after returning from an area where mosquitoes are abundant. She complains of an intense headache, pain behind her eyes, and severe muscle and joint pain so intense that she describes it as feeling like her bones are breaking.

A rash eventually appears, and moderate bleeding occurs.

What is the disease + its causative agent?

Dengue fever

arbovirus

A 34-year-old man develops a high fever three days after returning from a tropical region. He experiences severe, debilitating pain in his wrists, fingers, and ankles, accompanied by a rash and small blisters.

His fever improves, but the joint pain continues for several months.

What is the disease + its causative agent?

Chikungunya fever

arbovirus

A 40-year-old healthcare worker develops fever, severe headache, muscle and joint pain, and extreme fatigue after caring for a patient in Africa. Several days later, the patient develops profuse watery diarrhea, vomiting, severe abdominal pain, and both internal and external bleeding.

Blood pressure falls dramatically as the disease progresses.

What is the disease + its causative agent?

Ebola fever

orthoebolavirus

A 34-year-old man cleans a shed containing large amounts of rodent urine and feces. About one month later, he develops fever, chills, headache, dizziness, muscle aches, and gastrointestinal symptoms.

Several days later, he suddenly develops severe coughing, shortness of breath, fluid accumulation in the lungs, rapid heart rate, and dangerously low blood pressure.

What is the disease + its causative agent?

Hantavirus

A woman develops a high fever, severe chills, rapid heart rate, confusion, abdominal and pelvic pain, and foul-smelling vaginal discharge shortly after giving birth.

Her blood pressure drops dangerously low, and she becomes confused and difficult to awaken. Blood cultures reveal bacteria.

What is the disease + its causative agent?

Puerperal sepsis

group b streptococcus + S. agalactiae

A hospitalized patient develops a severe bacterial infection. Despite receiving antibiotics and fluids, the patient's blood pressure falls below 90 mmHg. The patient becomes confused, develops cold, clammy skin, difficulty breathing, and produces very little urine.

The physician explains that inadequate blood flow is causing kidney, cardiac, and respiratory failure.

What is the disease + its causative agent?

Septic shock

staph or strep

A farmer develops a painless skin lesion after handling an infected animal. The lesion progresses into a characteristic dark/black eschar.

Another patient exposed to the same organism develops severe respiratory symptoms after inhaling environmental material containing bacterial spores. The respiratory illness rapidly progresses to septic shock.

The organism is a Gram-positive, endospore-forming rod.

What is the disease + its causative agent?

Anthrax

Bacillus anthrasis

A patient sustains a deep traumatic wound contaminated with soil. Within a short period, the affected area becomes extremely painful and swollen. The skin changes color, large blisters form, and the patient feels a crackling sensation beneath the skin.

The wound produces a foul-smelling discharge, and the patient develops fever, rapid heart rate, and dangerously low blood pressure.

What is the disease + its causative agent?

Gas gangrene

A child living in an area where malaria is common develops a rapidly growing tumor involving the jaw. The disease is associated with Epstein-Barr virus and abnormal B cells.

The child is also immunosuppressed.

What is the disease + its causative agent?

Burkitt’s Lymphoma

A pregnant woman cleans a cat's litter box and later develops a mild flu-like illness with swollen lymph nodes and muscle aches. She is particularly concerned because the pathogen can cross from mother to fetus.

The organism is a protozoan parasite whose infectious form is an oocyst.

What is the disease + its causative agent?

Toxoplasmosis

toxoplasma gondii

A 21-year-old college student develops an itchy skin eruption after swimming in a freshwater lake. Several weeks later, he develops fever and flu-like symptoms.

The causative organism is a parasitic blood fluke, and infection occurs when microscopic larvae released by freshwater snails penetrate the skin.

What is the disease + its causative agent?

Schistosomiasis

A 27-year-old woman has a fever and cough for 5 days. Despite aggressive treatment with fluids and massive doses of antibiotics, she dies 5 hours after hospitalization. Catalase negative, gram-positive cocci are isolated from her blood?

What is the disease + its causative agent?

Staphylococci