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We investigated the persistence of viable Orientia tsutsugamushi in patients who had recovered from scrub typhus. Blood specimens were available from six patients with scrub typhus who were at 1 to 18 months after the onset of the illness. The EDTA-treated blood specimens were inoculated into ECV304 cells, and cultures were maintained for 7 months. Sequencing of the 56-kDa type-specific antigen gene of O. tsutsugamushi was performed to ascertain the homology of isolates. O. tsutsugamushi was isolated from all six patients, and nucleotide sequences of isolates serially collected from each patient were identical in all five patients in whom nucleotide sequences were compared. One patient relapsed 2 days after completion of antibiotic therapy; two patients complained of weakness for 1 to 2.5 months after the illness; one patient underwent coronary angioplasty 6 months later; and one patient suffered from a transient ischemic attack 8 months later. This finding suggests that O. tsutsugamushi causes chronic latent infection, which may be associated with certain clinical illnesses, preceded by scrub typhus. Antibiotic therapy abates the symptoms of scrub typhus, but does not eradicate O. tsutsugamushi from the human body.

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We describe the first case of Japanese spotted fever and the first isolate of spotted fever group rickettsia from a patient in South Korea. The isolated rickettsia from the patient was identified as Rickettsia japonica by analysis of the nucleotide sequences of 16S rRNA, gltA, ompA, ompB, and sca4 genes.

BackgroundAlthough severe malaria by Plasmodium vivax has been increasingly reported, there are marked variations in the type and rate of the complications by geographic area. This is possibly because of the presence of concurrent falciparum malaria or bacteraemia, and of differences in underlying immune status among the infected subjects. Furthermore, published studies on P. vivax in temperate regions are limited. The present study investigated severe vivax malaria in Korea, where only vivax malaria occurs. Hence, other compounding factors are rare. Additionally, most of the patients are possibly non-immune to this malarial disease.MethodsAdults with vivax malaria observed in one 860-bed university hospital from January 2006 to December 2012 were retrospectively evaluated. Seventeen patients who had travelled overseas within 6 months before the presentation of malaria were excluded. Severe vivax malaria was diagnosed according to World Health Organization criteria. Other complications were also investigated.ResultsTwo-hundred and ten patients were enrolled, of which 88 (41.9%) were treated as inpatients and the remainder as outpatients. Eleven patients were treated in an intensive care unit; among them, five patients received mechanical ventilation, and one needed extracorporeal membrane oxygenation therapy (ECMO) additionally. Severe vivax malaria was identified in 44 patients (21.0%), and the most common severe complication was pulmonary manifestation (40/188, 21.9%), which was followed by cerebral malaria (5/210, 2.4%), shock (4/210, 1.9%), spontaneous bleeding (3/210, 1.4%), metabolic acidosis (3/210, 3.5%) and acute kidney injury (2/210, 1.0%). Unusual complications, such as splenic infarction (ten patients) and retinal haemorrhage (two patients) were sometimes observed. There were no deaths, but the case involving ECMO was potentially fatal.Conclusions Plasmodium vivax infection can be severe to be fatal and is frequently associated with various complications in non-immune adults. The frequency of each complication seems to differ from other countries. Hence, further investigation is needed to elucidate the causes and mechanisms responsible for these differences.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-1684-4) contains supplementary material, which is available to authorized users.

A new additional melting peak is formed on the DSC thermogram as a result of preexpansion of poly(propylene-co-ethylene-co-1-butene) (terpolymer). The new melting peak appears at ∼152 °C, which is ∼12 °C higher than the tail end temperature (offset temperature) of the pristine terpolymer to exhibit a double melting peak. The origin of the new melting peak is traced to melting and recrystallization of less perfect crystals of the terpolymer at the preexpansion temperature, which situates usually between the onset and the offset temperature of the melting peak, contrary to the common presumption that the less perfect crystals are melted leaving the more perfect crystals intact during the preexpansion step and that the peak at ∼152 °C comes from melting of the more perfect crystals. The higher the temperature to which the terpolymer was heated above the offset temperature, the longer time of annealing was required at the preexpansion temperature for the new peak to appear. Once the terpolymer was completely melted by heating to 175 °C, at least 24 h of annealing was needed to show up the new melting peak, indicating that crystallization with homogeneous nucleation takes place much more slowly than that with self-nucleation.

PurposeNeisseria meningitidis is a leading cause of bacterial meningitis in young adults. University students, especially those living in dormitories, have been known to be at increased risk of meningococcal disease. We performed a longitudinal study to determine the carriage rates of N. meningitidis and the changes thereof.Materials and MethodsWe recruited Inha University freshmen who were, at that time, admitted to a student dormitory. A pharyngeal swab was taken from all participant who were also asked to complete a questionnaire. This was repeated four weeks later.ResultsA total of 136 students were enrolled at the first culture. After four weeks, 128 students were enrolled, including 106 re-participants. The overall carriage rates changed from 11.8% to 14.1%. In analysis of the 106 re-participants, "visiting to pubs" was associated with carriage of N. meningitis for both the first (p=0.047) and second cultures (p=0.026). Serogroup C was found to be the most frequent serogroup (5 isolates), while 3 isolates were found from serogroup B. The most prevalent PorA types were P1.22,14-6 (4 isolates) and P1.19,15 (3 isolates). The DNA sequences of PorA VR2 were changed in 2 students during prolonged carriage.ConclusionThe meningococcal carriage rate among first year university students who resided in a dormitory did not significantly increase over 4-week interval between cultures, which is markedly different from those reported in Western studies. Close social contact appeared to be related with carriage. Our data also revealed diversity in PorA types, suggesting the possibility of rapid mutation of the PorA gene during the 4-week interval.

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