Energy investment in reproduction is predicted to trade off against other necessary physiological functions like immunity, but it is unclear to what extent this impacts fitness in long-lived species. Among mammals, female primates, and especially apes, exhibit extensive periods of investment in each offspring. During this time, energy diverted to gestation and lactation is hypothesized to incur short and long-term deficits in maternal immunity and lead to accelerated ageing. We examined the relationship between reproduction and immunity, as measured by faecal parasite counts, in wild female chimpanzees ( Pan troglodytes schweinfurthii ) of Kibale National Park, Uganda. While we observed higher parasite shedding (counts of eggs, cysts and larvae) in pregnant chimpanzees relative to cycling females, parasites rapidly decreased during early lactation, the most energetically taxing phase of the reproductive cycle. Additionally, while our results indicate that parasite shedding increases with age, females with higher fertility for their age had lower faecal parasite counts. Such findings support the hypothesis that the relatively conservative rate of female reproduction in chimpanzees may be protective against the negative effects of reproductive effort on health. This article is part of the theme issue ‘Evolution of the primate ageing process’.

Infectious diseases may lead to ocular complications including uveitis, an ocular inflammatory condition with potentially sight-threatening sequelae, and conjunctivitis, inflammation of the conjunctiva. Emerging infectious pathogens with known ocular findings include Ebola virus, Zika virus, Avian influenza virus, Nipah virus, severe acute respiratory syndrome coronaviruses, and Dengue virus. Re-emerging pathogens with ocular findings include Toxoplasma gondii and Plasmodium species that lead to malaria. The concept of One Health involves a collaborative and interdisciplinary approach to achieve optimal health outcomes by combining human, animal, and environmental health factors. This approach examines the interconnected and often complex human-pathogen-intermediate host interactions in infectious diseases that may also result in ocular disease, including uveitis and conjunctivitis. Through a comprehensive review of the literature, we review the ophthalmic findings of emerging infectious diseases, pathogenesis, and One Health perspectives that provide further insight into the disease state. While eye care providers and vision researchers may often focus on key local aspects of disease process and management, additional perspective on host-pathogen-reservoir life cycles and transmission considerations, including environmental factors, may offer greater insight to improve outcomes for affected individuals and stakeholders.

Introduction: Highly Pathogenic Avian Influenza (HPAI) A(H5N1) represents a growing public health challenge, given broadening zoonotic vectors, with a previously reported human mortality rate of roughly 50%. Late March 2024 marked the start of a new outbreak of HPAI A(H5N1) in the United States. While offering unique public health challenges, this outbreak also provides insight into clinical presentation and ocular involvement implications, transmission vectors, and the implementation of successful surveillance strategies. Objectives: This review seeks to highlight current and historical outbreak trends, transmission and ocular tropism significance, and strategies to mitigate viral spread. Methods: A comprehensive narrative literature review was completed using PubMed database as well as local, federal, and international public health press releases. Discussion: The 2024 US outbreak of H5N1 demonstrates the unique adaptability of the virus. Traditionally transmitted to humans via infected poultry, this outbreak marks the first confirmed case of dairy cow-transmitted human infection. Unlike many past H5N1outbreaks, the majority of patients in the current US outbreak have presented with conjunctivitis either alone or alongside systemic symptoms. This ocular-specific disease manifestation offers new clinical and screening implications. Awareness of ophthalmic involvement among physicians and public health organizations can help guide screening candidates and identify potential infections.