At least 90 British military personnel have been diagnosed with confirmed cases of Q fever after serving in Afghanistan, a court has heard.
Humans can catch Q fever by breathing in dust from the faeces of infected farm animals such as sheep, cattle and goats.
Wayne Bass, a private with 2nd Battalion the Mercian Regiment, said his life has been ruined after catching the disease during a deployment to Helmand province in 2011/12 without being given antibiotics by the Army.
During his tour, his lawyers said, Mr Bass was in contact with goats and sheep and "was often required to take cover and jump through ditches and crawl along the ground - coming into contact with animal products and excrement".
Mr Bass, 34, was medically discharged from the Army in 2014 because of his Q fever and chronic fatigue symptoms.
Lieutenant Colonel Mark Bailey, a consultant in infectious diseases and tropical medicine, and a national expert in Q fever, gave evidence during the second day of the trial.
At Central London County Court on Tuesday, Lt Col Bailey, under questioning from Theo Huckle QC for Mr Bass, said he has 90 military and 10 civilian cases in his care after they were referred to him.
He confirmed the 90 had served in Helmand and said the number of military cases "built up from 2008".
He told the court:
"We have seen no new cases since 2014 from Afghanistan. Occasionally we get other military cases from other locations. Cyprus most recently."
Lt Col Bailey said he had seen "one British soldier who very, very nearly died" as a result of Q fever and subsequent complications, but there have been no UK deaths in his group.
He said he began treating Mr Bass in 2012 and he continues to see him as an outpatient in his clinic.
Dr Muhammad Munir, a virologist from Lancaster University, spoke to Forces News about Q fever.
The five-day trial will examine the extent of any duty owed by the Army to Mr Bass in relation to Q fever, and whether that duty was breached.
In court documents setting out the case, it is argued that the Ministry of Defence (MOD) should have considered using Doxycycline, an antibiotic used to treat Q fever, as an anti-malarial drug.
The MOD denies failing in its duty of care - pointing out that a vaccine used by some countries is not licensed in the UK.
Hearings are expected to continue until Friday, or possibly Monday, but its likely judgement will be reserved for some time after that.