Several members of the U.S. Armys 5307th Composite Unit (Merrills Marauders) died of the disease, as well as many soldiers in the Burma theatre; and before 1944, no effective antibiotics or vaccines were available.World War II provides some indicators that the disease is endemic to undeveloped areas in all of Oceania in the Pacific theater, although war records frequently lack definitive diagnoses, and many records of "high fever" evacuations were also likely to be other tropical illnesses. In the chapter entitled "The Green War", General MacArthurs biographer William Manchester identifies that the disease was one of a number of debilitating afflictions affecting both sides on New Guinea in the running bloody Kokoda battles over extremely harsh terrains under intense hardships— fought during a six-month span all along the Kokoda Track in 1942–43, and mentions that to be hospital-evacuated, Allied soldiers (who cycled forces) had to run a fever of 102 °F (39 °C), and that sickness casualties outnumbered weapons-inflicted casualties 5:1. Similarly, the illness was a casualty producer in all the jungle fighting of the land battles of the New Guinea campaign and the Guadalcanal campaign.
Scrub typhus or bush typhus  is a form of typhus caused by the intracellular parasite Orientia tsutsugamushi, a Gram-negative α-proteobacterium of family Rickettsiaceae first isolated and identified in 1930 in Japan.Although the disease is similar in presentation to other forms of typhus, its pathogen is no longer included in genus Rickettsia with the typhus bacteria proper, but in Orientia. The disease is thus frequently classified separately from the other typhi. Signs and symptoms
Signs and symptoms include fever, headache, muscle pain, cough, and gastrointestinal symptoms. More virulent strains of O. tsutsugamushi can cause hemorrhaging and intravascular coagulation. Morbilliform rash, eschar, splenomegaly, and lymphadenopathies are typical signs. Leukopenia and abnormal liver function tests are commonly seen in the early phase of the illness. Pneumonitis, encephalitis, and myocarditis occur in the late phase of illness. It has particularly been shown to be the most common cause of acute encephalitis syndrome in Bihar, India. Causes
Scrub typhus is transmitted by some species of trombiculid mites ("chiggers", particularly Leptotrombidium deliense), which are found in areas of heavy scrub vegetation. The mites feed on infected rodent hosts and subsequently transmit the parasite to other rodents and humans. The bite of this mite leaves a characteristic black eschar that is useful to the doctor for making the diagnosis.Scrub typhus is endemic to a part of the world known as the tsutsugamushi triangle (after O. tsutsugamushi).