First study of topical selamectin efficacy for treating cats naturally infected with Brugia malayi and Brugia pahangi under field conditions
Lymphatic filariae are important human and animal parasites. Infection by these parasites could lead to severe morbidity and has significant socioeconomic impacts. Topical selamectin is a semi-synthetic macrocyclic lactone that is widely used to prevent heartworm infection. Up until now, there were no studies that investigated the efficacy of selamectin in lymphatic filariae. Therefore, we aimed to study the chemotherapeutic and chemoprophylactic efficacies of selamectin use for cats in brugian filariasis-endemic areas in Southern Thailand. To assess chemotherapeutic efficacy of topical selamectin, eight Brugia malayi and six Brugia pahangi microfilaremic cats were treated with a single administration of topical selamectin. For chemoprophylactic efficacy assessment, a single application of topical selamectin was administrated to 9 healthy, uninfected cats. The cats in both groups were subjected to a monthly blood testing for microfilariae and filarial DNA for 1 year. Topical selamectin treatment in B. malayi and B. pahangi microfilaremic cats showed 100% effectivity in eradicating microfilaremia but only 78.5% effectivity in eliminating filarial DNA. In the chemoprophylactic group, selamectin demonstrated 66.7% efficacy in preventing B. malayi infection. Our findings suggest that a single administration of 6 mg/kg topical selamectin given every two months could effectively prevent B. malayi infection. Application of topical selamectin twice a year could block circulating microfilariae. Since there are no treatment guidelines currently available for lymphatic filarial infection in cats, the data obtained from this study could be used to guide the management of brugian lymphatic filarial infection in reservoir cats.
KeywordsThailand Selamectin Chemotherapeutic Chemoprophylaxis Brugia malayi Brugia pahangi Macrocyclic lactone
The authors would like to thank Ms. Bungon Sermsart and Ms. Hathai Nochote for assistance with the laboratory work and the staff of the Pikhunthong Royal Project for assistance with the field works.
Availability of data and material
All data generated or analyzed during this study are included in this published article and supplementary table.
The funding of this study was provided by the joint scholarship between the Faculty of Medicine Siriraj Hospital, Mahidol University and Zoetis (Thailand) Limited (Grand number: RO15933004).
Compliance with ethical standards
Consent for publication
The authors acknowledge the financial support from a Zoetis–Siriraj Joint Grant. Zoetis provided financial support for the field study, and Siriraj provided financial support for the laboratory analyses. Zoetis does not endorse the use of selamectin other than in strict accordance with the information provided on the product label.
- Boy MG, Six RH, Thomas CA, et al (2000) Efficacy and safety of selamectin against fleas and heartworms in dogs and cats presented as veterinary patients in North America. Ve Parasitol 91:233-2350Google Scholar
- Fisher M, Beck W, Hutchinson MJ (2007) Efficacy and safety of Selamectin (Stronghold®/Revolution™) used off-label in exotic pets. Intern J Appl Res Vet Med 5:87–94Google Scholar
- Mak JW (1984) Zoonotic filariasis in Malaysia. Malays Vet J 8:9–12Google Scholar
- Mak JW, Cheong WH, Yen PK, Lim PK, Chan WC (1982) Studies on the epidemiology of subperiordic Brugia malayi in Malaysia: problems in its control. Acta Trop 39:237–245Google Scholar
- Muslim A, Fong MY, Mahmud R, Sivanandam S (2013) Vector and reservoir host of a case of human Brugia pahangi infection in Selangor, peninsular Malaysia. Trop Biomed 30:727–730Google Scholar
- Palmieri JR, Ratiwayanto S, Masbar S, Tirtokusumo S, Rusch J, Marwoto HA (1985) Evidence of possible natural infections of man with Brugia pahangi in South Kalimantan (Borneo), Indonesia. Trop Geogr Med 37:239–244Google Scholar
- Partono F (1987) The spectrum of disease in lymphatic filariasis. In: Ciba Foundation, Evered D, Clark S (eds) Filariasis. Wiley, Chichester, pp 15–30Google Scholar
- Sagarasaeranee O, Krobtrakulchai T, Motana N, Jiraphongsa C (2017) Filariasis: Brugia pahangi prevention and control guideline. Weekly Epidemiological surveillance Report, Thailand. Bureau of Epidemiology, Ministry of Public Health 47:145–151Google Scholar
- Wongkamchai S, Boitano JJ, Knowawisetsut L (2016) Biology, morphology and life cycle. In: Wongkamchai S (ed) Lymphatic filariasis. Thammada Press, BangkokGoogle Scholar
- World Health Organization (1992) Lymphatic filariasis: the disease and its control. Fifth report of the WHO Expert Committee on Filariasis. World Health Organ Tech Rep Ser 821:1–71Google Scholar