Anaplasma phagocytophilum Infection in Ticks, China–Russia Border

To the Editor: Anaplasma phagocytophilum, an emerging human pathogen of public health importance, is transmitted to humans most commonly by tick bites (1). The agent has been detected in various species of Ixodes ticks around the world (2) and in Dermacentor silvarum ticks in northeastern People’s Republic of China (3), where 3 A. phagocytophilum strains were isolated from wild and domestic animals (4). In the Asiatic region of Russia adjacent to China, A. phagocytophilum was identified in Ixodes persulcatus ticks, and A. bovis in Haemaphysalis concinna ticks (5). Human granulocytic anaplasmosis was reported in the southern area of the Russian Far East that borders China (6). The objectives of this study were to investigate the prevalence of A. phagocytophilum in ticks collected from the China–Russia border and to characterize the agent by molecular biology techniques.

immunocompromised patients, the endogenous autoinfection cycle may result in the overproduction and dissemination of larvae into intestinal and extraintestinal tissues, including the central nervous system, leading to the hyperinfection syndrome which can be lethal (5). Most cases (96%) occur in immigrants, but some have been described in patients with a history of travel, sometimes many years previously. S. stercoralis infections have been reported up to 65 years after initial exposure in veterans who served in Asia during World War II (4,6).
Although our patient exhibited poor general condition, he likely did not experience hyperinfection syndrome because he was not immunosuppressed, and he completely recovered after receiving standard ivermectin treatment. That the patient was originally infected in the Canary Islands seems improbable, although a low level of transmission exists in rural and disadvantaged areas in continental Spain, Portugal, and Italy (7). We did not fi nd evidence of Strongyloides spp. transmission in the Canary Islands. In particular, the patient stayed in a high-status tourist hotel for a short period, and he never walked in bare feet. He was probably infected when he lived in Vietnam.
This case highlights the importance of systematically considering chronic strongyloidiasis when seeking a diagnosis for persistent hypereosinophilia, even in patients with no underlying disease, and the value of systematically obtaining any history of travel in disease-endemic areas even if it occurred many years previously. The endogenous autoinfection cycle can possibly persist for a lifetime. In addition, systematic examination of stool samples should be carried out, and ivermectin should be given when an immunosuppressive drug is required in a patient who has a history of travel to, or residence in, an area to which strongyloidiasis is endemic.  (5). Human granulocytic anaplasmosis was reported in the southern area of the Russian Far East that borders China (6). The objectives of this study were to investigate the prevalence of A. phagocytophilum in ticks collected from the China-Russia border and to characterize the agent by molecular biology techniques.
During May-June 2009, hostseeking ticks were collected by fl agging vegetation of grassland or woodland along the China-Russia border. Attached ticks were collected from sheep and goats in Hunchun, and from dogs in Suifenhe (Table). All ticks were identifi ed by morphologic features to the species level and the developmental stage by 2 entomologists (Y. Sun and R.-M. Xu). DNA was extracted from tick samples by using Tissue DNA Extract kit (Tiangen Biotechnique Inc., Beijing, China), following the instructions of the manufacturer. Nested PCR was performed to amplify partial citrate synthase gene (gltA) of A. phagocytophilum as previously described (7). To avoid possible contamination, DNA extraction, the LETTERS reagent setup, amplifi cation, and agarose gel electrophoresis were performed in separate rooms, and negative control samples (distilled water) were included in each amplifi cation.
A. phagocytophilum was detected in 83 of 2,429 adult ticks, with an overall prevalence of 3.42% (Table). The infection rates in the 14 survey sites ranged from 0 to 5.96%, and were signifi cantly different (χ 2

Japanese Encephalitis, Tibet, China
To the Editor: Tibet is located in the Qinghai-Tibet Plateau of western People's Republic of China and has been internationally recognized as a Japanese encephalitis (JE)nonendemic area because the average altitude is thought to be too high to facilitate the cycle of Japanese encephalitis virus (JEV) between mosquitoes and vertebrates (1,2). In addition, JE is a reportable infectious disease in China, and no clinically confi rmed case has been reported in Tibet since establishment of a national case reporting system in 1951 (3,4). Neither the mosquito vector of JEV nor JEV isolates have been described in Tibet. In this study, JEV was isolated from Culex tritaeniorhynchus mosquitoes, the main vectors of JEV, collected in Tibet. Serologic assays detected anti-JEV antibodies in a large number of human and porcine serum samples collected in this region. These data demonstrate that JEV is currently circulating in Tibet.