Outbreaks of Paederus dermatitis have been reported in several Asia-Pacific countries when rove beetles (genus Paederus) are accidentally brushed or crushed on the skin, releasing haemolymph pederin. An investigation was conducted in a school to ascertain the causative agent, establish the case definition, epidemiological characterisation of cases, entomological and environmental survey and data analysis. This outbreak occurred among 36 schoolchildren attending a night tuition class conducted by their teacher. Dermatitis developed within 24 hours in 33/37 (89.2%) cases with itchiness as the first presenting symptom in 87.9% of cases. Periorbital oedema and erythematous-vesicular plaques on the upper extremities were seen in 57.6% of cases, on the back (36.4%) and on the nape (24.2%). Signs and symptoms were present 12 hours after exposure in 66.7% of cases with burning sensation within four hours in 9.1%. Seven cases received out-patient treatment. Thirty cases (90.9%) recalled exposure to Paederus fuscipes with 28 (84.8%) cases admitting crushing or brushing the insects. (Relative risk = 2.2; 95% CI: 1.2; 4.2). The school with fluorescent lighting, was located next to paddy fields. P. fuscipes was easily found in the paddy fields and along the school corridors. This strongly supports it as the likely causative agent for the dermatitis. Boarding the ventilation panes and use of insect spray were successfully implemented to control the outbreak. Increased awareness of this condition is important to prevent misdiagnosis.
Orientia tsutsugamushi is the causative agent of scrub typhus vectored by larval stages of trombiculid mites (chiggers) that occur in most tropical regions of Southeast Asia. A total of 242 chiggers extracted from eight small mammals captured from a positive scrub typhus locality in Kelantan, Malaysia, were screened for the presence of O. tsutsugamushi. The chiggers were grouped in 16 pools for extraction of DNA prior to screening of O. tsutsugamushi based on the nucleotide sequence of 56-kDa type specific antigen (TSA) gene using nested polymerase chain reaction. Two species of on-host chiggers were identified, the one, Leptotrombidium deliense, much more dominant (94.8%) than the other, Ascoshoengastia sp. (5.2%). The pathogen was detected in two pools (12.5%) of L. deliense recovered from Rattus rattus and Tupaia sp. The 56-kDa TSA gene sequence analysis revealed the O. tsutsugamushi harboured in those chiggers were Karp prototype strain with high similarity (99.3%). Findings of this study strongly supported the existence of scrub typhus infections in certain parts of Malaysia which agrees with previous local reports. Moreover, this study highlighted the pressing need of a large-scale close observation of O. tsutsugamushi DNA sequences from chiggers that can probably be collected from other positive scrub typhus localities to precisely provide the distribution and prevalence of this zoonotic pathogen.