Environmental drivers of parasitic nematode infection in wild ungulates in the Serengeti National Park

Basil C Senso; Jason E Donaldson; T Michael Anderson; Aidan Trentinus; Vanessa O Ezenwa; Ricardo M Holdo

doi:10.1016/j.ijpara.2026.104772

Environmental drivers of parasitic nematode infection in wild ungulates in the Serengeti National Park

Int J Parasitol. 2026 Jun;56(6):104772. doi: 10.1016/j.ijpara.2026.104772. Epub 2026 Jan 19.

Authors

Basil C Senso¹, Jason E Donaldson², T Michael Anderson³, Aidan Trentinus⁴, Vanessa O Ezenwa⁵, Ricardo M Holdo⁶

Affiliations

¹ Odum School of Ecology, University of Georgia, Athens 30602, GA, USA; Center for the Ecology of Infectious Diseases, University of Georgia, Athens 30602, GA, USA; Nicholas School of the Environment, Duke University, Durham 27710, NC, USA. Electronic address: basil.senso@duke.edu.
² Nicholas School of the Environment, Duke University, Durham 27710, NC, USA.
³ Biology Department, Wake Forest University, Winston-Salem 27109, NC, USA.
⁴ Tanzania Centre for Research Cooperation, P. O. Box 10952, Arusha, Tanzania.
⁵ Department of Ecology and Evolutionary Biology, Yale University, New Haven 06511, CT, USA.
⁶ Odum School of Ecology, University of Georgia, Athens 30602, GA, USA.

PMID: 41565096
DOI: 10.1016/j.ijpara.2026.104772

Abstract

Parasite infections in host populations frequently display seasonal patterns that can shape host behavior, fitness, and population dynamics. Despite recognition that seasonality plays a key role in infection dynamics across numerous host-parasite systems, the drivers of seasonal infection dynamics for parasites with different life cycles are often unknown. This lack of system-specific understanding restricts our ability to predict when and why parasite infections and their cascading effects on host populations will have the greatest impact. We investigated how seasonality and environmental variables at the likely time of infection are related to the infection intensity of two parasitic nematodes with contrasting life cycles: strongyle nematodes (direct life cycle) and lungworms (indirect life cycle). We conducted the study in two free-ranging ungulate species in Serengeti National Park, Tanzania: Coke's hartebeest (Alcelaphus buselaphus) and topi (Damaliscus lunatus). We found a high prevalence of both parasites, with strongyle nematodes occurring in 95.5% of hartebeest and 93.1% of topi, and lungworms occurring in 100% of hartebeest and 99.7% of topi. Strongyle infection intensity peaked in the wet season but showed no strong association with precipitation, temperature, or animal density at the likely time of infection. In contrast, lungworm intensity peaked in the dry season and was associated negatively with precipitation and positively with animal occupancy. Our results highlight the importance of considering how parasite life cycles interact with environmental variables operating at different temporal scales, as seasonal infection patterns may emerge from processes acting at distinct times relative to parasite development and transmission. Identifying when parasite intensities are highest is critical for predicting when hosts are under the greatest ecological pressure due to parasitism.

Keywords: Alcelaphine; Gastrointestinal nematodes; Lungworms; Parasite seasonal dynamics; Tropical savannah.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Animals, Wild / parasitology
Environment
Female
Host-Parasite Interactions
Life Cycle Stages
Nematoda
Nematode Infections* / epidemiology
Nematode Infections* / parasitology
Nematode Infections* / veterinary
Parks, Recreational
Prevalence
Ruminants* / parasitology
Seasons
Tanzania / epidemiology

Grants and funding

#2021-67015-33407/USDA