Let me present you with a new hypothesis of Alexander's illness in Tarsus:
Pontiac fever. It's a natural (non-poison) hypothesis but it doesn't have any adverse long-term effects on health.
There is a type of bacteria called
Legionella and it causes one of two lung diseases:
Legionnaires' disease - a type of severe pneumonia
Pontiac fever - a mild respiratory disease (without pneumonia)
Legionella can be found in rivers:
Illnesses usually occur in the summer and early fall:
https://www.osha.gov/legionnaires-disease.
Alexander may have drunk some of the river water or it might have gotten into his lungs while he was drowning in shock.
Disease transmission primarily occurs through inhaling Legionella-contaminated, aerosolized water. While rare, exposure is also possible from breathing in (i.e., aspirating) Legionella contaminated soil or
while drinking water.
https://www.osha.gov/legionnaires-disea ... nformation
So what's the difference between Legionnaires' disease and Pontiac fever?
Pontiac fever symptoms:
Duration of Pontiac fever (within a week):
Legionnaires' disease symptoms:
Early symptoms may include low-grade fever, headache, aching joints (arthralgia) and muscles (myalgia), tiredness, and appetite loss. Later symptoms include high fever ranging from 39° to 41°C (102°-105°F), cough (dry at first, later producing phlegm), difficulty in breathing, chills, and chest pain. Gastrointestinal symptoms may include vomiting, diarrhea, nausea, and abdominal pain.
https://www.osha.gov/legionnaires-disea ... nformation
Duration of Legionnaire's disease (several weeks):
Untreated Legionnaires’ disease usually worsens during the first week. In common with other risk factors causing severe pneumonia, the most frequent complications of legionellosis are respiratory failure, shock and acute kidney and multi-organ failure. Recovery always requires antibiotic treatment, and is usually complete,
after several weeks or months.
https://www.who.int/news-room/fact-shee ... ionellosis
In young healthy adults, Legionnaires' disease is rare (just like pneumonia or malaria) and the attack rate is less than 5%. On the other hand, Pontiac fever seems to affect mainly young people and the attack rate is over 90%.
Source:
https://www.osha.gov/legionnaires-disea ... nformation
Source:
https://en.wikipedia.org/wiki/Pontiac_fever
The incubation period of Legionnaires' disease is usually 2-10 days, for Pontiac fever it could be just hours:
There is another case when someone drank water from the Cydnus river and got ill. Al-Ma'mun, the seventh Abbasid caliph, who reigned from 813 until his death in 833, drank water from that river and later died. I think he probably got the Legionnaire's disease (he was 46).
Source:
https://en.wikipedia.org/wiki/Al-Ma%27m ... and_legacy
So I think I changed my mind about Alexander's illness at Tarsus, he probably had just Pontiac fever and was not poisoned. However, I still think Parmenion wanted Alexander's death even then in Tarsus. He didn't have to poison Alexander but when he got information that Alexander is seriously ill maybe he sent the letter to prevent Alexander's curing by Philip.