Infectious Disease Diagnosis Cases

Infectious disease diagnosis cases on Saturn Dx help you practise reasoning about fever, rash, cough, diarrhea and sepsis. This free infection diagnosis game gives you 125 clinical cases, each revealed one hint at a time.

How our infectious disease diagnosis cases work

Pick a difficulty (Easy, Medium or Hard) and start a case. You see the patient presentation first. Type your diagnosis, and if it is wrong the next hint unlocks: examination findings, then laboratory results, then imaging or other investigations. The fewer hints you need, the more points you earn, and at the end you read a short explanation of why the diagnosis fits.

Why practise infectious disease diagnosis cases?

Infections can affect any organ, so the diagnosis depends on exposure, travel, vaccination, immune status and the pattern of symptoms as much as on any test. A fever with a headache might be a viral illness or meningitis, and the difference matters. These cases teach you to combine the story with examination findings and laboratory results to decide on the most likely organism and site.

What you learn from each case

Every one of these infectious disease diagnosis cases ends with the same three things: the correct diagnosis, a short explanation of the reasoning, and the full list of clues so you can see where your thinking went right or wrong. Over time you start to recognise typical patterns in infectious system medicine, you remember the key investigations for each condition, and you become faster at ruling out the dangerous causes first. Use the difficulty setting to begin with classic presentations and then move on to harder, more subtle cases.

Topics in the infectious system diagnosis game

This area of medicine covers presentations such as:

• sepsis and septic shock
• meningitis and encephalitis
• tuberculosis
• malaria and other travel-related fevers
• HIV and opportunistic infections
• viral hepatitis
• infective endocarditis
• typhoid, brucellosis and other tropical and zoonotic infections

How to approach a infectious system case

Start by deciding how unwell the patient is, because sepsis changes the order of everything. Then ask where the infection is, who is at risk and what the patient was exposed to. Compare the hints with the likely organism: a white cell count, a culture result or an imaging finding often decides between bacterial, viral, fungal and parasitic causes.

• Write down two or three possible diagnoses before you type an answer.
• Use every hint to rule something in or out, not only to confirm your first idea.
• Read the explanation after each case, even when you were right.

Trusted resources to read next

After a case, deepen your understanding with Centers for Disease Control and Prevention for guidance on infectious diseases and prevention, and MedlinePlus infections for plain-language summaries of infections.

Keep studying with Saturn Medic

Test yourself with the Saturn Medic Question Bank, revise key facts with our medical flashcards, or return to the medical diagnosis game home page. You can also practise another system:

• Cardiovascular diagnosis cases
• Respiratory diagnosis cases
• Gastrointestinal diagnosis cases
• Endocrinology diagnosis cases
• Renal System diagnosis cases
• Hematology diagnosis cases

Infectious System diagnosis game FAQ

Are these infectious disease diagnosis cases free?

Yes. Every infectious system case on Saturn Dx is free to play, and there is no limit on how many you can try. There are currently 125 infectious system cases.

How many hints do I get in a infectious system case?

Each case has between four and six clues. You start with the history, and every wrong answer unlocks the next hint, such as examination findings, laboratory results or imaging.

Are the infectious system cases real patients?

No. They are original teaching scenarios written to match standard textbook presentations. Our team reviews each case before it goes live, and no real patient records are used.

All 125 infectious system cases

1. Infectious System case #119 - A 35-year-old man has had fever for 3 days.
2. Infectious System case #120 - A 26-year-old woman has had a fever for 5 days.
3. Infectious System case #181 - A 30-year-old man from a flooded village without clean drinking water has had sudden profuse watery diarrhoea for 6 hours.
4. Infectious System case #182 - A 29-year-old man has had a skin sore on his forearm for 3 months that is slowly getting bigger.
5. Infectious System case #183 - A 45-year-old farmer has had 3 days of stiffness in the jaw and difficulty opening his mouth.
6. Infectious System case #184 - A 19-year-old university student living in a crowded hostel has had a fever and severe headache since yesterday.
7. Infectious System case #185 - A 35-year-old shepherd has had 3 weeks of fever that peaks in the evening, with drenching sweats, tiredness and aching joints.
8. Infectious System case #186 - A 4-year-old boy has had a fever that comes and goes for 2 months, and he has become pale and thin.
9. Infectious System case #187 - A 38-year-old woman living on a sheep farm has had a vague dull ache in the right upper abdomen for 6 months.
10. Infectious System case #188 - A 33-year-old man has had 10 days of fever with sweating and a dull ache in the right upper abdomen.
11. Infectious System case #189 - A 38-year-old man who slaughters sheep has had 3 days of sudden fever with chills, severe headache and muscle pains.
12. Infectious System case #190 - A 28-year-old man has noticed blood at the end of passing urine for 3 months.
13. Infectious System case #263 - A 4-year-old unvaccinated boy has had 3 days of fever, runny nose, red eyes and a dry cough.
14. Infectious System case #264 - A 9-year-old girl has had 2 days of fever and headache and now complains of pain near her right ear.
15. Infectious System case #265 - A 6-year-old boy has had a mild fever and tiredness for a day, and then develops an itchy rash.
16. Infectious System case #266 - A 25-year-old man returned two weeks ago from a camping trip where he drank untreated stream water; he now has bloating, nausea and…
17. Infectious System case #267 - A 23-year-old man has had burning on passing urine for 3 days.
18. Infectious System case #268 - A 31-year-old man has had sudden high fever, headache and severe muscle aches for 4 days.
19. Infectious System case #269 - A 19-year-old student has had a severe sore throat and marked tiredness for 8 days.
20. Infectious System case #270 - A 30-year-old man has had a generalised rash for 10 days, with mild fever, malaise and headache.
21. Infectious System case #271 - A 36-year-old man has had a dry cough, fever and weight loss for 5 weeks, with breathlessness that is getting worse on walking.
22. Infectious System case #272 - A 27-year-old man has had 5 days of fever, sore throat and malaise.
23. Infectious System case #273 - A 35-year-old farmer has had 3 days of fever, malaise and tingling with itching around an old scar on his left hand.
24. Infectious System case #274 - A 44-year-old man has had fever, chills and a severe headache for 5 days.
25. Infectious System case #275 - A 40-year-old man has had 4 days of fever, headache and muscle aches.
26. Infectious System case #424 - A 24-year-old student returned from Bangladesh 5 days ago and has had 3 days of sudden high fever, severe backache and pain behind the eyes.
27. Infectious System case #425 - A 35-year-old teacher develops sudden fever, malaise, muscle aches and a dry cough in January; several colleagues have the same illness.
28. Infectious System case #426 - A 30-year-old man returned from Pakistan 5 months ago, having stopped taking tablets at the end of the trip; he now has several days of…
29. Infectious System case #427 - An unvaccinated 6-year-old boy from a rural area has had 3 days of sore throat, low fever and a blood-stained nasal discharge.
30. Infectious System case #428 - A 40-year-old man who sorts raw animal hides at a rural workshop has had an itchy spot on his forearm for 3 days.
31. Infectious System case #429 - A 34-year-old farmer from a rural part of India has had a pale patch on his thigh for a year that he cannot feel when scratched.
32. Infectious System case #430 - A 7-year-old malnourished boy in a tropical rural area has had vague abdominal pain and, two weeks earlier, a cough with wheeze and an…
33. Infectious System case #431 - A 6-year-old girl has intense anal itching that is worse at night and sleeps badly; her younger brother has the same problem.
34. Infectious System case #432 - A 38-year-old man who often eats rare beef is embarrassed to find flat white segments in his underwear and stool.
35. Infectious System case #433 - A 12-year-old barefoot farm boy in the tropics is tired and breathless; some weeks ago he had an itchy rash on his feet and later a dry…
36. Infectious System case #434 - A 45-year-old man who worked barefoot in rice fields in the Far East 20 years ago has recurrent itchy, linear weals across his buttocks and…
37. Infectious System case #435 - A 36-year-old man from coastal Indonesia has had recurrent fevers with a painful red streak running up his leg and swelling of the left…
38. Infectious System case #436 - A 33-year-old man back from 2 years in the rainforests of Cameroon has recurrent itchy, tense swellings on his forearms that last several…
39. Infectious System case #437 - A 28-year-old man clearing forest for a plantation in northern India has had 4 days of sudden fever, retro-orbital headache, cough and…
40. Infectious System case #438 - A refugee in an overcrowded camp has had 4 days of sudden rigors, severe frontal headache, back and limb pains and constipation; others in…
41. Infectious System case #439 - A 32-year-old farmer from the Democratic Republic of Congo has had months of irregular fevers and headaches, with sleepiness by day and…
42. Infectious System case #440 - A 27-year-old veterinary nurse has had 3 weeks of painless neck swelling and mild tiredness, with no sore throat.
43. Infectious System case #441 - A 30-year-old man born in Somalia has had 4 weeks of worsening headache, low-grade fever and weight loss, and now vomits and is drowsy.
44. Infectious System case #442 - A 62-year-old man in intensive care after bowel surgery, fed intravenously through a central line and given broad-spectrum antibiotics, has…
45. Infectious System case #443 - Two relatives become unwell 24 hours after eating home-canned vegetables, with blurred vision, double vision and difficulty swallowing.
46. Infectious System case #444 - A 58-year-old man treated with high-dose prednisolone for 4 weeks for giant cell arteritis develops abdominal pain, distension, cough and…
47. Infectious System case #445 - A 40-year-old woman with acute leukaemia has had fever for 10 days despite antibiotics, even though her neutrophil count has recovered, and…
48. Infectious System case #446 - A 55-year-old man who had his spleen removed 10 years ago developed fever, sweats and malaise two weeks after a camping holiday in the…
49. Infectious System case #447 - A 29-year-old poultry farmer in Vietnam, whose chickens have been dying in large numbers for a week, develops fever, cough and watery…
50. Infectious System case #448 - A 9-year-old boy has had 3 days of fever, diarrhoea and right lower abdominal pain, one week after a barbecue with under-cooked pork.
51. Infectious System case #729 - A 68-year-old woman has had three days of burning, band-like discomfort along the right side of her chest wall, and she feels slightly…
52. Infectious System case #730 - A 19-year-old student has had two days of mild fever and a rash that began on her face; she never completed her childhood vaccine course.
53. Infectious System case #731 - A 6-year-old has had three days of mild fever and a runny nose; two of his classmates had the same illness last week.
54. Infectious System case #732 - A 3-year-old who attends nursery has had two days of fever and has stopped eating; two other children at the nursery are also ill.
55. Infectious System case #733 - A 14-month-old boy has had three days of fever up to 39.8 degrees C, yet he is playful between peaks; he had one brief febrile convulsion…
56. Infectious System case #734 - A 58-year-old man has had four days of fever, dry cough and marked fatigue; his wife developed similar symptoms last week.
57. Infectious System case #735 - A 5-month-old infant born at 33 weeks has had two days of a runny nose followed by cough, noisy breathing and poor feeding in mid-winter.
58. Infectious System case #736 - Forty passengers on a cruise ship, including a 34-year-old woman, develop sudden profuse vomiting and diarrhoea about 36 hours after a…
59. Infectious System case #737 - A 14-month-old attending nursery has had two days of watery diarrhoea, vomiting and fever in the winter months.
60. Infectious System case #738 - Four members of a family develop diarrhoea and abdominal cramps two days after a barbecue with undercooked chicken and egg-based mayonnaise.
61. Infectious System case #739 - A 24-year-old man has had three days of severe colicky abdominal pain, then diarrhoea that is now bloody, after eating undercooked chicken…
62. Infectious System case #740 - A 78-year-old woman in residential care took clindamycin for a chest infection a week ago and now has eight watery stools daily with lower…
63. Infectious System case #741 - A 21-year-old woman has had four days of painful lesions on the vulva and burning on passing urine; she has a new sexual partner.
64. Infectious System case #742 - A 20-year-old woman attends a clinic after her partner was told he had an infection; she has had intermenstrual and post-coital bleeding…
65. Infectious System case #743 - A 28-year-old woman has had five days of an itchy, profuse, frothy yellow-green vaginal discharge, vulval soreness and pain during sex.
66. Infectious System case #744 - A 30-year-old woman notes a thin off-white vaginal discharge with a fishy odour, worse after sex and during her period, but no itch or…
67. Infectious System case #745 - A 22-year-old man has noticed several painless flesh-coloured lumps near the foreskin over six weeks; there is no ulcer or discharge.
68. Infectious System case #746 - A 62-year-old man has had two weeks of a sore mouth and altered taste, starting soon after a course of antibiotics.
69. Infectious System case #747 - A 7-year-old has had two days of sore throat, fever and vomiting; a classmate had a similar illness last week.
70. Infectious System case #748 - A 26-year-old woman returned from a Caribbean beach holiday two weeks ago with an intensely itchy lesion on her foot.
71. Infectious System case #749 - A 34-year-old man with HIV who stopped treatment months ago has had three weeks of progressive headache, vomiting and drowsiness.
72. Infectious System case #750 - A 29-year-old man with HIV and poor adherence to therapy has had ten days of headache and confusion, then a seizure yesterday.
73. Infectious System case #751 - A 41-year-old man with untreated HIV has had two weeks of painless blurred vision and floaters in the right eye.
74. Infectious System case #752 - A 36-year-old man with advanced untreated HIV has noticed dark purple spots on his legs and mouth over three months, and one leg has become…
75. Infectious System case #753 - A 31-year-old man with advanced HIV has had six weeks of profuse watery diarrhoea and has lost 8 kg.
76. Infectious System case #754 - A 7-year-old boy who has lived all his life in a rural West African village has had swelling of the face and legs for three weeks; months…
77. Infectious System case #755 - A 30-year-old nurse who cared for a patient with fever and bleeding in a rural hospital nine days ago has had sudden fever, headache and…
78. Infectious System case #756 - A 38-year-old unvaccinated traveller returned five days ago from a forest area in West Africa with a mild fever, headache and muscle pain…
79. Infectious System case #757 - A 40-year-old forester from a deer-tick area has had three weeks of malaise and joint pains, followed by a drooping right face.
80. Infectious System case #758 - A 19-year-old woman on the third day of her period has had abrupt high fever, vomiting, a sore throat and aching muscles.
81. Infectious System case #759 - A 58-year-old man with poorly controlled diabetes has severe thigh pain two days after drainage of a groin abscess, with fever and…
82. Infectious System case #760 - A 9-year-old girl has had a firm lump in the left armpit for three weeks and a low-grade fever; she was not unwell before.
83. Infectious System case #761 - A 3-year-old child living in a mud-walled house with a thatched roof in rural Bolivia has had one week of fever.
84. Infectious System case #762 - A 35-year-old farmer from a riverside village in West Africa has had intense itching for two years and recent blurring of vision.
85. Infectious System case #763 - A 32-year-old man who grew up in rural Peru has had his first generalised seizure; he is otherwise well and takes no medication.
86. Infectious System case #764 - A 29-year-old farm labourer in north-east Brazil has had six months of vague abdominal pain and frequent stools containing blood-stained…
87. Infectious System case #765 - A 23-year-old woman has had four days of lower abdominal pain, deep pain during sex and an abnormal vaginal discharge, with a fever; she…
88. Infectious System case #766 - A 29-year-old man had four days of fever, headache, malaise and a sore throat, then painful lesions around his anus and mouth; he had close…
89. Infectious System case #767 - A 33-year-old hunter returned three days ago from a rural area where this disease is endemic with sudden rigors, severe headache and fever…
90. Infectious System case #768 - A 52-year-old man has had three days of fever and headache, followed by a generalised seizure and odd behaviour.
91. Infectious System case #769 - A 27-year-old woman who recently returned from a village in northern Nigeria has had six days of gradually rising fever, sore throat and…
92. Infectious System case #770 - A 38-year-old man with untreated HIV who used to clear bat droppings from a cave has had four weeks of fever, weight loss and a skin…
93. Infectious System case #771 - A 55-year-old man with poorly controlled type 2 diabetes, recently treated with steroids for a respiratory virus infection, has had three…
94. Infectious System case #772 - A 33-year-old man from northern Thailand with untreated HIV has had three weeks of fever, weight loss and a generalised skin eruption.
95. Infectious System case #773 - A 30-year-old man with HIV and pulmonary tuberculosis started antituberculosis treatment six weeks ago and antiretroviral therapy three…
96. Infectious System case #774 - A 28-year-old farmer from a remote village in Chad, who drinks water from an open pond, has an intensely painful swelling on the lower leg.
97. Infectious System case #775 - A 52-year-old rice farmer with poorly controlled diabetes in northern Thailand has had three weeks of fever, productive cough and weight…
98. Infectious System case #776 - A 41-year-old hunter has had five days of fever and chills and a painful lump in the right armpit, a week after skinning wild rabbits.
99. Infectious System case #777 - A 39-year-old man with advanced untreated HIV has had six weeks of progressive weakness in the left arm, clumsiness and difficulty seeing…
100. Infectious System case #778 - A 10-day-old boy, born at term to a mother who attended no antenatal care, is feeding poorly and breathing fast.
101. Infectious System case #779 - A 11-year-old boy from a village near a rainforest swamp in West Africa has a small painless lump on his forearm that has been present for…
102. Infectious System case #930 - A 29-year-old woman, 30 weeks pregnant, has had fever, muscle aches and tiredness for three days. She ate soft cheese and pâté at a party…
103. Infectious System case #931 - A 19-year-old student has had intense itching for three weeks, worse at night. Two of his flatmates have developed the same itch.
104. Infectious System case #932 - A 9-year-old boy has an itchy red ring-shaped patch on his forearm that has slowly enlarged over three weeks. The family has a new kitten.
105. Infectious System case #933 - A 5-year-old girl has many small painless bumps on her trunk and arms that have increased in number over two months. A classmate has…
106. Infectious System case #934 - A 7-year-old girl from a dry, dusty village with scarce water has had red, irritated, watery eyes for months. Several of her siblings are…
107. Infectious System case #935 - A 4-year-old boy in a rural area with poor sanitation has had chronic loose stools with mucus and poor weight gain for a year. He plays in…
108. Infectious System case #936 - A 68-year-old woman with type 2 diabetes has had a painful red swelling of her right lower leg for two days with chills, after scratching…
109. Infectious System case #937 - A 26-year-old man returned from West Africa two weeks ago and now has a painful sore on his penis. He had unprotected sex with a new…
110. Infectious System case #938 - A 34-year-old woman returned from the Caribbean four days ago with a sudden fever, headache and severe joint pains in her hands and wrists.
111. Infectious System case #939 - A 27-year-old woman, 14 weeks pregnant, returned from Brazil last week with a mild fever, joint aches, red eyes and an itchy rash.
112. Infectious System case #940 - A 45-year-old man who works sorting imported animal hides has had two days of fever, dry cough, headache and chest discomfort. He felt…
113. Infectious System case #941 - A 40-year-old farmer in a humid tropical region walks barefoot and has had a slowly growing warty lesion on his right foot for four years…
114. Infectious System case #942 - A 52-year-old gardener who prunes roses developed a small painless nodule on the right index finger after a thorn prick three weeks ago.
115. Infectious System case #943 - A 33-year-old farmer from a dry tropical region has had a painless swelling of his right foot for three years. Small openings have appeared…
116. Infectious System case #944 - A 6-year-old boy from a rural rice-farming area of South-East Asia has had fever, headache and vomiting for three days and then became…
117. Infectious System case #945 - A 31-year-old miner from Uganda who works in a bat-inhabited cave has had a high fever, severe headache and muscle pains for four days.
118. Infectious System case #946 - A 47-year-old hiker from the south-eastern United States has had fever, chills, headache and aching muscles for five days, starting a week…
119. Infectious System case #947 - A 9-year-old boy from a remote rural village in the tropics has had a growing, non-painful crusted sore on his leg for two months. Several…
120. Infectious System case #948 - A 16-year-old boy in a hot, humid region has a rapidly enlarging painful ulcer on his shin after a minor scratch from a bush 10 days ago.
121. Infectious System case #949 - A 25-year-old man who slept in a mud-walled house in East Africa has had three episodes of high fever with rigors, each lasting about three…
122. Infectious System case #950 - A 22-year-old man living in a crowded displacement camp in East Africa has had a sudden high fever with severe headache and aching limbs…
123. Infectious System case #951 - Twelve guests at a wedding in a rural area develop nausea and diarrhoea 24–48 hours after eating home-cured sausage. A 34-year-old man's…
124. Infectious System case #952 - A 29-year-old man who has sex with men has had anal pain, rectal discharge with blood and a feeling of incomplete emptying for two weeks…
125. Infectious System case #953 - A 33-year-old man from a rural area in Papua New Guinea has had a painless, slowly enlarging genital sore for two months. He has had…

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