Parasitology Research

, Volume 118, Issue 4, pp 1289–1297 | Cite as

First study of topical selamectin efficacy for treating cats naturally infected with Brugia malayi and Brugia pahangi under field conditions

  • Patsharaporn T. Sarasombath
  • Suwich Thammapalo
  • Sumart Loymek
  • Anchisa Angkanasinsiri
  • Patcharin Priyavoravong
  • Sirichit WongkamchaiEmail author
Treatment and Prophylaxis - Original Paper


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.


Thailand 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

Not applicable.

Competing interests

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.

Supplementary material

436_2019_6248_MOESM1_ESM.doc (90 kb)
Supplementary table 1 Number of B. malayi and B. pahangi microfilariae recovered from Giemsa thick blood smear (Mf/ml) and presence of B. malayi and B. pahangi DNA by HRM real-time PCR in cat blood before, during, and after topical selamectin treatment (CN1–CN8, B. malayi-infected cats; CS1–CS6, B. pahangi-infected cats; NC1, untreated control B. malayi-infected cats; NC-2, untreated control B. pahangi-infected cats) (DOC 89 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Patsharaporn T. Sarasombath
    • 1
  • Suwich Thammapalo
    • 2
  • Sumart Loymek
    • 2
  • Anchisa Angkanasinsiri
    • 1
  • Patcharin Priyavoravong
    • 3
  • Sirichit Wongkamchai
    • 1
    Email author
  1. 1.Department of Parasitology, Faculty of Medicine Siriraj HospitalMahidol UniversityBangkokThailand
  2. 2.Office of Disease Prevention and Control Region 12 Songkhla, Department of Disease ControlMinistry of Public HealthSongkhlaThailand
  3. 3.Zoetis (Thailand) LimitedBang Rak DistrictThailand

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