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Reappearance of Lymphatic Filariasis in Indonesia Tied to Animal Reservoirs

Strategic Insights

— 1 min read

A study published in PLOS Neglected Tropical Diseases has found that the reappearance of Brugia malayi infection in humans in Indonesia's Belitung District may be due to reintroduction from animal reservoirs. The district received mass drug administration (MDA) between 2006 and 2010, and subsequent transmission assessment surveys (TAS) showed a decline in microfilaria (Mf) prevalence. However, a 2021 survey revealed a 2.1% Mf prevalence in humans, prompting further investigation.

Key Takeaways:

  • Brugia malayi is the most common cause of lymphatic filariasis (LF) in Indonesia, and a zoophilic ecotype infects both humans and animals.
  • A survey in five villages in 2021 showed a microfilaria (Mf) prevalence of 2.1% in humans, indicating a potential reappearance of B. malayi infection.
  • The district received five annual rounds of mass drug administration (MDA) between 2006 and 2010 and passed three transmission assessment surveys (TAS) in subsequent years.
  • The study found that B. malayi Mf were detected in 1.4% of cat, 7.3% of dog, and 13.5% of crab-eating macaque samples by microscopy.
  • Quantitative PCR (qPCR) detected B. malayi DNA in 4.1% of cat, 2.4% of dog, and 13.5% of macaque samples.
  • Infections or co-infections with B. pahangi (cats, dogs) or D. immitis (dogs) were detected, highlighting the complexity of filarial infections in animals.
  • Microscopy was found to be less accurate for detection and species identification of Mf compared to qPCR.
  • The study concludes that more research is needed to better understand B. malayi transmission between animals and humans in endemic areas.

Statistics:

  • 2.1% microfilaria (Mf) prevalence in humans in five villages in 2021.
  • 1.4% of cat, 7.3% of dog, and 13.5% of crab-eating macaque samples showed B. malayi Mf by microscopy.
  • 4.1% of cat, 2.4% of dog, and 13.5% of macaque samples showed B. malayi DNA by qPCR.
  • 20.3% of crab-eating macaques showed a novel Dirofilaria species.
  • The district received five annual rounds of mass drug administration (MDA) between 2006 and 2010.

Sources:

  • PLOS Neglected Tropical Diseases, 2025;19(10).
  • Public Library Science, 1160 Battery Street, Ste 100, San Francisco, CA 94111, USA.
  • University Indonesia, Dept. of Parasitology, Faculty of Medicine, Jakarta, Indonesia.
  • NewsRx, Life Science Weekly, October 21, 2025, p 7273.

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