ProMED-mail has a recent report by Sai Gon Giai Phong about the identification of the cause of the skin disease in Quang Ngai. It also has a very useful analysis of the story. Excerpt:
The news report above says that rickettsiae were identified in 14 of 26 blood samples. What test was used to accomplish this identification is not specified, nor is the rickettsial species specified. The Rickettsia genus describes small obligate intracellular parasites that are maintained in animal and arthropod reservoirs and transmitted by arthropod vectors (ticks, fleas, lice, or mites) to humans.
Scrub typhus and murine typhus are likely the most common rickettsial diseases in Viet Nam (http://cid.oxfordjournals.org/content/34/Supplement_4/S145.full). Scrub typhus, caused by Orientia tsutsugamushi , a rickettsial organism, is transmitted by bite of larval mites (chiggers), which serve as both the vector and the reservoir. Rodents of (rats and mice) are common hosts for the mites.
Fever, headache, lymphadenopathy, myalgias, a sore at the site of the chigger bite, and rash that is unlike the rash described in patients in the current outbreak are common. Patients with severe scrub typhus can develop multiorgan failure and disseminated intravascular coagulopathy (DIC) with hemorrhage, with mortality rates 1-30 per cent in untreated patients.
Murine typhus is a fleaborne rickettsial disease caused by Rickettsia typhi. Rats are the primary animal reservoir of R. typhi. Humans are usually infected by contact with infected flea feces, either by inoculation into excoriated fleabites, inhalation, or ingestion. Symptoms include fever, headache, chills, vomiting, nausea, myalgias, and a rash that is unlike the rash described in patients in the current outbreak. Murine typhus usually resolves within 3 weeks, even if untreated. However up to 4 per cent of patients sick enough to be hospitalized will die from the infection.
The news report above also says that 30 per cent of the tested blood samples had erythrocytes that were small and fragile, suggesting the possibility of hemolysis, which can occur in scrub typhus with DIC. Obviously we need more information as to the way the diagnosis of rickettsial infection was made.
