title: Rickettsial infection among military personnel deployed in Northern Sri Lanka.
abstract: BACKGROUND
  Military personnel deployed in field actvities report on frequent tick bites. Therefore they may run the risk of exposure to rickettsial organisms.
  
  
  METHODS
  In order to assess the risk of exposure to rickettsial organisms, two groups of military personnel who were deployed in field activities of Nothern Sri Lanka were investigated. The first group was studied in order to assess the sero-prevalence of rickettsioses and consisted of soldiers who were admitted following injuries during field activities. The second group was studied to identify the incidence of acute rickettsioses during their acute febrile presentations. They were tested with IFA-IgG against spotted fever group rickettsioses (SFG), scrub typhus (ST) and murine typhus.
  
  
  RESULTS
  In the first group, 48/57 (84%) military personnel had serological evidence of exposure to rickettsioses (in all, IFA-IgG titer ≥ 1:128): 33/50 (66%) to SFG rickettsioses, 1/50 (2%) to ST and 14/50 (28%) had mixed titers for both (in all, titers were higher for SFG). While all of them were in military uniform most of the time and frequently slept on scrub land, 35/57 (61.4%) had never used insect repellents and none were on doxycycline prophylaxis. 48/57 (84%) had experienced tick bites during field activity. In the second group, there were 49 who presented with acute febrile illness with a mean duration of 8.5 days (SD 3.2). 33/49 (67.3%) were serologically positive for acute rickettsioses (IgG ≥1:256); 26 (79%) due to ST and 7 (21%) due to SFG rickettsioses,
  
  
  CONCLUSIONS
  Exposure to rickettsial disease was common among soldiers who were deployed in Northern Sri Lanka. Scrub typhus was the predominent species accounting for acute febrile illness. Further studies are needed to understand the reasons for very high sero-prevalence for SFG rickettsioses with no anticedent febrile illness. Use of preventive measures was not satisfactory. The high sero-prevelence of SFG rickettsioses is likely to interfere with serological diagnosis of acute SFG rickettsioses in this population.
authors.affiliation: Departments of Medicine, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka. ranjanp64@gmail.com.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Premaratna
authors.affiliation: Military Hospital, Colombo, Sri Lanka. nimalkaa@yahoo.com.
authors.forename: Nimalka
authors.initials: N
authors.lastname: Ariyaratna
authors.affiliation: Military Hospital, Palali, Sri Lanka. champaka_attanayaka@yahoo.com.
authors.forename: Champaka
authors.initials: C
authors.lastname: Attanayake
authors.affiliation: Department of Microbiology, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka. bandarankb@gmail.com.
authors.forename: Wijesinghe
authors.initials: W
authors.lastname: Bandara
authors.affiliation: Department of Parasitology, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka. nilminicha@gmail.com.
authors.forename: Nilmini
authors.initials: N
authors.lastname: Chandrasena
authors.affiliation: Departments of Medicine, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka. hjanakadesilva@gmail.com.
authors.forename: H Janaka
authors.initials: HJ
authors.lastname: de Silva
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000276:immunology*; D006801:Humans; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data*; D015995:Prevalence; D012281:Rickettsia / Q000276:immunology*; D012282:Rickettsia Infections / Q000453:epidemiology / Q000276:immunology; D012373:Rocky Mountain Spotted Fever / Q000453:epidemiology* / Q000276:immunology; D012612:Scrub Typhus / Q000453:epidemiology* / Q000276:immunology; D016036:Seroepidemiologic Studies; D013188:Sri Lanka / Q000453:epidemiology; D014437:Typhus, Endemic Flea-Borne / Q000453:epidemiology* / Q000276:immunology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial