In The Adventure of the Dying Detective¹ an esoteric fatal infectious disease called the Tapanuli fever is used as a biological weapon by a criminal named Culverton Smith. Holmes speaks of him thus to his friend Dr Watson:

Smith cultured the bacteria on gelatin, brought the specimens back to London and infected his nephew, who died within four days. Sherlock Holmes suspected homicide. Culverton Smith then attempts to infect Holmes, but Holmes anticipates and avoids the booby trap. He fakes the illness very cleverly, deceiving even Watson, who describes him with clinical precision!

Convinced that Holmes is dying, Watson is sent to persuade Culverton Smith to come and treat him. Dr Watson narrates his meeting with Smith.

Smith is convinced that his plan to infect and kill Holmes is working. He behaves as predicted by Holmes. By allowing Smith to gloat over him, Holmes draws him to confess and also reveal the modus operandi. Watson secretly witnesses the conversation:

Sherlock Holmes gets Culverton Smith arrested on the charges of murder and attempted murder, and after the arrest Holmes takes Watson into his confidence:

What can be deduced about ‘Tapanuli fever’ or ‘the black corruption of Formosa’? This infectious disease must be prevalent in South-East Asia and should have outbreaks among plantation workers in Sumatra—Indonesia. It should have a short incubation period and a high case fatality rate. The organism should be easily cultured and transmissible by needlestick injury. Holmes avoids examination by telling Watson that disease is ‘highly contagious by touch’. This, it emerges, was only a ruse to prevent Watson from finding out about the faked illness. The disease expert Culverton Smith shakes Holmes and touches him without any concern for his own safety.

The candidate infectious disease should also explain the clinical features that Holmes simulated so cleverly. Tapanuli fever should cause fever, anorexia, severe fatigue and sweating. The patient would also have cramping body ache, dyspnoea, cough and a croaking and feeble voice. Lips would have dark crusts and pupils would be dilated. Delirium usually heralds imminent death in this disease. Readers are referred to the definitive report on this matter by Sodeman². Among the possible causes are scrub typhus, anthrax, typhoid fever and primary septicaemic plague. Sodeman rightly remarks that Conan Doyle is unlikely to have selected a commonplace disease such as typhoid fever or anthrax as the ‘deadly Asiatic infection’ for use in murder. Typhus endemic in South-East Asia, including Sumatra, is an attractive possibility. It is caused by Rickettsia tsutsugamushi transmitted by mites or chiggers. It could account for an earlier reference made by Sherlock Holmes to ‘the giant rat of Sumatra’. Holmes was involved in the investigation of the ship Matilda Briggs which seems to have carried a cargo of rats from Sumatra³. Culverton Smith might have imported these rats. Holmes was probably aware of the role of Sumatran rats as a natural host of the vector for the disease—hence his familiarity with the Tapanuli fever. However, scrub typhus is unlikely to be Tapanuli fever, because rickettsia would be difficult to culture on gelatin. And although it is a serious infection, case fatality is not very high, making it a poor choice as a murder weapon.

The presence of dysphonia suggests the possibility of diphtheria. There are reports of non-toxigenic strains of Corynebacterium diphtheriae that cause severe systemic disease with aggressive course and high mortality. An outbreak of severe invasive infection by non-toxigenic C. diphtheriae among Swiss intravenous drug users⁴ suggests that needle-stick injury could be a mode of transmission. But once again, diphtheria was a well-known local disease in England and therefore unlikely to have been chosen by Conan Doyle.

New evidence strongly supports the case for acute septicaemic melioidosis, as suggested by Sodeman. Whitmore and Krishnaswami first reported melioidosis in 1912 among the morphine addicts in Rangoon, Burma. They described acute septicaemic melioidosis with rapid onset, a short course and high mortality. Melioidosis, also known as Whitmore's disease, is caused by Berkholderia pseudomallei infection. Conan Doyle could have come across Whitmore and Krishnaswami's report in his medical readings before writing this particular story in 1913. In 1987 melioidosis was responsible for 20% of all cases of community-acquired septicaemia in a large study in Thailand⁵, which is geographically similar to Sumatra—Indonesia. B. pseudomallei was the single most common organism isolated in the monsoon months from July to September, and in August it caused 50% of all documented cases of community-acquired septicaemia. The disease commonly affects rice paddy farmers, and Culverton Smith could have studied septicaemic melioidosis among his plantation workers in Sumatra. In 1987, even with the availability of potent antibiotics, mortality from septicaemic melioidosis was very high at 68%. Over 50% of deaths occurred within 48 hours. Melioidosis can cause the clinical features simulated by Sherlock Holmes. In the study of septicaemic melioidosis reported from Thailand, most of the patients became profoundly ill soon after the onset of fever. Metabolic acidosis and blood-borne pneumonia was found to be common, which could explain why Holmes was ‘struggling for breath’ and coughing. A patient with such a severe septic illness is likely to have a ‘feeble’ croaking voice. Septic shock would explain the severe fatigue, anorexia, cold sweats and delirium. Dark crusts on the lips could be from the subcutaneous abscesses seen with melioidosis or activation of herpes labialis. B. pseudomallei is culturable in gelatin agar and could easily have been imported to England from the plantations of Sumatra. To this day, according to a research letter published in The Lancet, almost all cases of melioidosis in England are imported from South-East Asia and tropical Australia⁶. Even more fascinating is a Lancet letter⁷ entitled ‘A deadly thorn’, describing the case of a 61-year-old man who returned to England after a 2-week holiday in Thailand. While gardening the next day he stood on a large thorn which penetrated his left heel through the sole of the shoes that he had worn throughout his vacation in Thailand. He developed melioidosis and died. The skin and shoes were probably colonized with B. pseudomallei in Thailand, and the thorn then inoculated the bacteria. This case provides modern evidence to strengthen the case for melioidosis as the ‘deadly Asiatic disease’ described by Conan Doyle.

If B. pseudomallei was indeed the murder weapon, Culverton Smith chose well. Should his victim escape death from acute septicaemic melioidosis, there was always a strong possibility of late relapse or rupture of a visceral abscess. Delayed death from melioidosis has earned it the name of ‘the Vietnamese time bomb’⁸. The Centers for Disease Control and Prevention have identified B. pseudomallei as a potential agent for bioterrorism⁹. Culverton Smith's use of the postal service to deliver the lethal infection has an echo today. Life, sometimes regrettably, does imitate art.