title: Emergence of multi-acaricide resistant Rhipicephalus ticks and its implication on chemical tick control in Uganda.
abstract: BACKGROUND
  Acaricide failure has been on the rise in the western and central cattle corridor of Uganda. In this study, we identified the tick species associated with acaricide failure and determined their susceptibility to various acaricide molecules used for tick control in Uganda.
  
  
  METHODS
  In this cross sectional study, tick samples were collected and identified to species level from 54 purposively selected farms (from 17 districts) that mostly had a history of acaricide failure. Larval packet test was used to screen 31 tick populations from 30 farms for susceptibility at discriminating dose (DD) and 2 × DD of five panels of commercial acaricide molecules belonging to the following classes; amidine, synthetic pyrethroid (SP), organophosphate (OP) and OP-SP co-formulations (COF). Resistance was assessed based on World Health Organization criteria for screening insecticide resistance.
  
  
  RESULTS
  Of the 1357 ticks identified, Rhipicephalus (Rhipicephalus) appendiculatus and Rhipicephalus (Boophilus) decoloratus were the major (95.6%) tick species in farms sampled. Resistance against SP was detected in 90.0% (27/30) of the tick populations tested. Worryingly, 60.0% (18/30) and 63.0% (19/30) of the above ticks were super resistant (0% mortality) against 2 × DD cypermethrin and deltamethrin, respectively. Resistance was also detected against COF (43.3%), OP chlorfenvinphos (13.3%) and amitraz (12.9%). In two years, 74.1% (20/27) of the farms had used two to three acaricide molecules, and 55.6% (15/27) rotated the molecules wrongly. Multi-acaricide resistance (at least 2 molecules) was detected in 55.2% (16/29) of the resistant Rhipicephalus ticks and significantly associated with R. decoloratus (p = 0.0133), use of both SP and COF in the last 2 years (p < 0.001) and Kiruhura district (p = 0.0339). Despite emergence of amitraz resistance in the greater Bushenyi area, it was the most efficacious molecule against SP and COF resistant ticks.
  
  
  CONCLUSIONS
  This study is the first to report emergence of super SP resistant and multi-acaricide resistant Rhipicephalus ticks in Uganda. Amitraz was the best acaricide against SP and COF resistant ticks. However, in the absence of technical interventions, farmer-led solutions aimed at troubleshooting for efficacy of multitude of acaricides at their disposal are expected to potentially cause negative collateral effects on future chemical tick control options, animal welfare and public health.
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. vpato@covab.mak.ac.ug.|Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. vpato@covab.mak.ac.ug.|National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan. vpato@covab.mak.ac.ug.
authors.forename: Patrick
authors.initials: P
authors.lastname: Vudriko
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. jokwee@yahoo.co.uk.
authors.forename: James
authors.initials: J
authors.lastname: Okwee-Acai
authors.affiliation: Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. tayebwa.dickson@gmail.com.
authors.forename: Dickson Stuart
authors.initials: DS
authors.lastname: Tayebwa
authors.affiliation: Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. josephjbvincent@gmail.com.
authors.forename: Joseph
authors.initials: J
authors.lastname: Byaruhanga
authors.affiliation: Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. ksteven310@gmail.com.
authors.forename: Steven
authors.initials: S
authors.lastname: Kakooza
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. ewampande@yahoo.co.uk.|Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. ewampande@yahoo.co.uk.
authors.forename: Edward
authors.initials: E
authors.lastname: Wampande
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. omararoberto@gmail.com.
authors.forename: Robert
authors.initials: R
authors.lastname: Omara
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. mjeannebukeka@gmail.com.|Drug Information Department, National Drug Authority, P. O. Box 23096, Kampala, Uganda. mjeannebukeka@gmail.com.
authors.forename: Jeanne Bukeka
authors.initials: JB
authors.lastname: Muhindo
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. rtweyongyere@covab.mak.ac.ug.|Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. rtweyongyere@covab.mak.ac.ug.
authors.forename: Robert
authors.initials: R
authors.lastname: Tweyongyere
authors.affiliation: Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. dowiny@covab.mak.ac.ug.|Directorate of Research and Graduate Training, Makerere University, P.O Box 7062, Kampala, Uganda. dowiny@covab.mak.ac.ug.
authors.forename: David Okello
authors.initials: DO
authors.lastname: Owiny
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Animal Health, National Agricultural and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan. htakeshi@med.kitasato-u.ac.jp.|Present Address: Department of Parasitology, Kitasato University School of Medicine, Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan. htakeshi@med.kitasato-u.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hatta
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Animal Health, National Agricultural and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan. tsujin@med.kitasato-u.ac.jp.|Present Address: Department of Parasitology, Kitasato University School of Medicine, Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0374, Japan. tsujin@med.kitasato-u.ac.jp.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Tsuji
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan. umemiya@obihiro.ac.jp.
authors.forename: Rika
authors.initials: R
authors.lastname: Umemiya-Shirafuji
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan. gen@obihiro.ac.jp.
authors.forename: Xuenan
authors.initials: X
authors.lastname: Xuan
authors.affiliation: Central Diagnostic Laboratory, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P. O Box 7062, Kampala, Uganda. harukana@koalanet.ne.jp.|Present Address: Japan International Cooperation Agency, Nibancho Center Building, 5-25, Nibancho, Chiyoda-ku, Tokyo, 108-8012, Japan. harukana@koalanet.ne.jp.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kanameda
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Animal Health, National Agricultural and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki, 305-0856, Japan. acarikf@nifty.com.
authors.forename: Kozo
authors.initials: K
authors.lastname: Fujisaki
authors.affiliation: National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan. hisuzuki@obihiro.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D056810:Acaricides / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000517:prevention & control*; D002709:Chlorfenvinphos / Q000494:pharmacology; D003430:Cross-Sectional Studies; D018432:Drug Resistance, Multiple; D005260:Female; D007814:Larva; D009570:Nitriles / Q000494:pharmacology; D010755:Organophosphates / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology; D048494:Rhipicephalus / Q000187:drug effects*; D013983:Tick Control / Q000379:methods*; D013984:Tick Infestations / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D014052:Toluidines / Q000494:pharmacology; D014454:Uganda / Q000453:epidemiology
chemical_list: D056810:Acaricides; D009570:Nitriles; D010755:Organophosphates; D011722:Pyrethrins; D014052:Toluidines; C017160:cypermethrin; C017180:decamethrin; C014983:amitraz; D002709:Chlorfenvinphos