[Disseminated tuberculosis revealed by epididymal localization in an immunocompetent patient: a case report]. / Tuberculose disséminée révélée par une localisation épididymaire chez un patient immunocompétent: à propos d'un cas.

Epididymal tuberculosis is rare and often presents diagnostic difficulties. It may be indicative of a disseminated form of the infection, which is the case of our patient. A 19-year-old man, with no past medical history, was admitted for a swollen painful left scrotum that had been evolving for 8 months. He had undergone an orchiectomy and the anatomopathological examination was consistent with epididymal tuberculosis. The radiological investigations had revealed other localizations of the infection: lymphatic, pulmonary, parietal and osteoarticular tuberculosis. Anti-tuberculosis therapy was introduced. However, in the 4th month of treatment, the patient developed seizures. A cerebral magnetic resonance imaging was practiced, concluding to cerebral tuberculomas. Anti-tuberculosis treatment was continued associated to an anticonvulsant with a favourable outcome. The originality of our observation resides in the mode of revelation of a disseminated paucisymptomatic tuberculosis, by an epididymal localization, in an immunocompetent patient.

Dehydration followed by restraint sustains high circulating corticosterone and improves immunity in toads.

Amphibians are suffering population declines due to a variety of factors such as increased ultraviolet radiation, climate change, habitat loss, pathogens, and pollution, or a combination of these. Such changes are associated with a reduction in the availability of water, exposing these animals to a greater risk of desiccation. In this context, understanding how dehydration can modulate the hypothalamic-pituitary-interrenal axis (HPI) and the immune response is an imperative question to predict how stressors can affect amphibian species. We investigated whether dehydration promotes long-lasting effects on toads' ability to respond to a consecutive stressor (restraint) even if the toads are allowed to rehydrate, as well as its effects on the immune function. We also tested the hypothesis that the toads showing more severe dehydration would exhibit lower responsiveness to restraint challenge, even if the animals were allowed to rehydrate. Individuals of R. ornata were dehydrated mildly and severely. Thereafter, they were submitted to a restraint stress challenge for 1 and 24 h. Our results show that dehydration increased hematocrit and CORT in R. ornata toads. The restraint induced an acute stress response in fully hydrated toads (increased CORT and neutrophil: lymphocyte ratio). Otherwise, restraint in moistened cloth bags allowed full rehydration in previously dehydrated toads and did not induce an additional increase in CORT, but those toads sustained elevated CORT up to 24 h of restraint. Also, these animals showed increased neutrophil: lymphocyte ratio and the phagocytic activity of blood cells, even when they rehydrated during restraint. These results point to a continuous activation of the HPA during dehydration and subsequent restraint, even when they recovered from the dehydration state. Also, acute stressors seem to promote immune cell redistribution and augmentation of immune cellular function in R. ornata toads.

Evaluating patient immunocompetence through antibody response to pneumococcal polysaccharide vaccine using a newly developed 23 serotype multiplexed assay.

Assessing T-cell independent antibody response to polysaccharide vaccines is crucial for diagnosing humoral immune deficiencies. However, immunocompetence criteria based on S. pneumoniae vaccination remain unclear. We evaluated IgG antibody vaccine response in healthy individuals to establish interpretive criteria. Pre- and 4-week post-vaccination sera were collected from 79 adults. Antibody concentrations to PNEUMOVAX 23 serotypes were measured using a multiplexed platform. Immunocompetence was determined by fold increase in post-vaccination response, percentage of serotypes achieving 4- or 2-fold antibody ratio, and post-vaccination concentration ≥ 1.3 µg/mL. Immunogenicity varied widely across the 23 serotypes (26.6% to 94.9% for ≥4-fold increase, 51.9% to 98.7% for ≥2-fold increase). Immunocompetence based on historic criteria of ≥4-fold increase in antibody ratio to ≥70% of serotypes was low (72.2%), but increased to 98.7% with criteria of at least a 2-fold increase and/or post-vaccination concentration ≥ 1.3 µg/mL. Current criteria for assessing immunocompetence may be overly stringent and require updating.

Significance of successive feeding of sources of n-3 fatty acids to broiler breeders and their progeny on growth performance, intestinal lesion scores, lymphoid organs weight and plasma immunoglobulin A in broiler chickens challenged with Eimeria.

The study examined the effects of successive feeding of sources of n-3 PUFA to broiler breeders (BB) and their progeny in broiler chickens challenged with Eimeria. The BB were fed: 1) control (CON), corn-soybean meal diet, 2) CON + 1 % microalgae (DMA), as a source of DHA and 3) CON + 2.50% co-extruded full fat flaxseed (FFF), as a source of ALA. Eggs were hatched at 34, 44, and 54 wk of age. Posthatch treatments (BB-progeny) were: CON-CON, DMA-CON, FFF-CON, DMA-DMA and FFF-FFF with diets formulated for starter (d 1-10) and grower/finisher (d 11-42) phases. All chicks were orally challenged with Eimeria (E. acervulina and E. maxima) on d 10. Relative to CON, DMA and FFF increased concentration of n-3 PUFA by ≥ 2-fold in hatching eggs and progeny diets. There were no (P > 0.05) interactions between treatment and BB age on d 0 to 10 growth. In general, BB age affected (P < 0.05) growth performance throughout the study. In the starter phase, successive exposure to DHA and ALA improved FCR over CON-CON (P < 0.01). The interaction between treatment and BB age in grower/finisher was such that DHA exposure to younger BB resulted in poor growth performance (P < 0.05) relative to exposure to older BB. In contrast, exposure to ALA had similar (P > 0.05) growth performance irrespective of BB age. Moreover, successive exposure to ALA resulted in higher BWG, breast weight and lower FCR compared to successive exposure to DHA (P < 0.05). There were no (P > 0.05) interactions between treatment and BB age on the intestinal lesion scores, lymphoid organ weights and concentration of plasma immunoglobulin A (IgA). Successive exposure to DHA resulted in higher (P = 0.006) jejunal lesion scores than CON-CON birds. The results showed that successive exposure of DHA and ALA improved FCR relative to non-exposed birds in the starter phase. However, responses in the grower/finisher phase depended on n-3 PUFA type, with birds on successive ALA exposure supporting better growth and breast yield than birds on successive DHA exposure.

Disseminated cerebral cryptococcoma mimicking glioblastoma - A case report."

We discuss a rare instance of cryptococcoma caused by Cryptococcus gattii in a 55-year-old woman initially treated for suspected COVID bronchopneumonia. The diagnosis posed a challenge due to vague symptoms and unclear imaging findings suggesting malignancy. Postoperative samples confirmed the presence of Cryptococcus gattii through culture of brain tissue and blood. Appropriate therapy was initiated, but despite treatment, it led to a fatal outcome. The case emphasizes the crucial role of microbiologist in early diagnosis of fungal infections of Central Nervous System. Additionally, the delayed diagnosis in immunocompetent individuals highlights the critical need for early recognition and intervention to mitigate potentially fatal outcomes.

The marine sponge, Hymeniacidon sinapium, displays allorecognition of siblings during post-larval settling and metamorphosis to juveniles.

Marine sponges, including the crumb of bread sponge, Hymeniacidon sinapium, display allorejection responses to contact with conspecifics in both experimental and natural settings. These responses have been used to infer immunocompetence in a variety of marine invertebrates. However, larvae and juveniles from several marine sponge species fuse and form chimeras. Some of these chimeras persist, whereas others eventually break down, revealing a period of allogeneic non-responsiveness that varies depending on the species. Alternatively, for H. sinapium, most pairs of sibling post-larvae and juveniles that settle in contact initiate immediate allorecognition and show the same morphological response progression as the adults. This indicates that allorecognition and response occurs during early metamorphosis. Results from H. sinapium and other sponge species, in addition to annotations of sponge genomes, suggest that allorecognition and immunocompetence in sponges are mediated by distinct systems and may become functional at different times during or after metamorphosis for different species. Consequently, allorecognition may not be a good proxy for the onset of immunocompetence.

Laryngeal Mycosis in an Immunocompetent Patient: A Case Report.

Laryngeal mycosis, a condition often overlooked in systemically immunocompetent individuals, requires heightened clinical vigilance for accurate diagnosis. The disease mimics symptoms of other laryngeal conditions such as gastroesophageal reflux, granulomatous disease, keratosis, and glottic malignancies, with risk factors including prolonged use of antibiotics, inhaled steroids, and smoking. Clinically, it presents with variable symptoms including hoarseness, and occasionally pain, dysphagia, and odynophagia. Diagnosis involves the observation of hyperkeratosis, notably when intraepithelial neutrophils are present, prompting further investigation for fungal elements through specialized staining. Effective management encompasses prolonged systemic antifungal treatment and the elimination of predisposing factors to prevent recurrence or treatment failure. Despite its potential to mimic a range of laryngeal diseases, laryngeal mycosis remains a less considered differential diagnosis. This is compounded by the commonality of risk factors in the general population, including prolonged antibiotic use, inhaled steroid therapy, and smoking habits, which may predispose individuals to fungal infections of the larynx. Furthermore, the necessity for a high index of suspicion and specialized diagnostic techniques, such as the identification of hyperkeratosis with intraepithelial neutrophils through biopsy and specialized staining for fungal elements, underscores the complexity of diagnosing this condition. The rationale for documenting this case report is multifaceted, primarily focusing on the fact that laryngeal mycosis is rare among immunocompetent patients leading to under-recognition of laryngeal mycosis in systemically immunocompetent individuals and the diagnostic challenges it presents. Additionally, the documentation seeks to emphasize the critical need for comprehensive treatment approaches, including prolonged systemic antifungal therapy and the identification and elimination of predisposing factors, to ensure effective management and prevent recurrence.

Complex effects of testosterone level on ectoparasite load in a ground squirrel: an experimental test for the immunocompetence handicap hypothesis.

BACKGROUND: The immunocompetence handicap hypothesis suggests that males with a higher testosterone level should be better at developing male secondary traits, but at a cost of suppressed immune performance. As a result, we should expect that males with an increased testosterone level also possess a higher parasite load. However, previous empirical studies aimed to test this prediction have generated mixed results. Meanwhile, the effect of testosterone level on parasite load in female hosts remains poorly known. METHODS: In this study, we tested this prediction by manipulating testosterone level in Daurian ground squirrels (Spermophilus dauricus), a medium-sized rodent widely distributed in northeast Asia. S. dauricus is an important host of ticks and fleas and often viewed as a considerable reservoir of plague. Live-trapped S. dauricus were injected with either tea oil (control group) or testosterone (treatment group) and then released. A total of 10 days later, the rodents were recaptured and checked for ectoparasites. Fecal samples were also collected to measure testosterone level of each individual. RESULTS: We found that testosterone manipulation and sex of hosts interacted to affect tick load. At the end of the experiment, male squirrels subjected to testosterone implantation had an averagely higher tick load than males from the control group. However, this pattern was not found in females. Moreover, testosterone manipulation did not significantly affect flea load in S. dauricus. CONCLUSIONS: Our results only lent limited support for the immunocompetence handicap hypothesis, suggesting that the role of testosterone on regulating parasite load is relatively complex, and may largely depend on parasite type and gender of hosts.

Mycophenolate mofetil hampers antibody responses to a broad range of vaccinations in kidney transplant recipients: Results from a randomized controlled study.

OBJECTIVES: To study the effect of mycophenolate mofetil (MMF) on various vaccination responses in kidney transplant recipients. METHODS: In a randomized controlled trial (EudraCT nr.: 2014-001372-66), low immunologically risk kidney transplant recipients were randomized to TAC/MMF or TAC-monotherapy (TACmono), six months post-transplantation. One year after transplantation, in a pre-specified sub-study, recipients were vaccinated against pneumococcus, tetanus and influenza. Blood was sampled before and 21 days after vaccination. Adequate vaccination responses were defined by international criteria. A post-hoc analysis was conducted on SARS-CoV-2 vaccination responses within the same cohort. RESULTS: Seventy-one recipients received pneumococcal and tetanus vaccines (TAC/MMF: n = 37, TACmono: n = 34), with 29 also vaccinated against influenza. When vaccinated, recipients were 60 (54-66) years old, with median eGFR of 54 (44-67) ml/min, tacrolimus trough levels 6.1 (5.4-7.0) ug/L in both groups and TAC/MMF daily MMF dose of 1000 (500-2000) mg. Adequate vaccination responses were: pneumococcal (TAC/MMF 43%, TACmono 74%, p = 0.016), tetanus (TAC/MMF 35%, TACmono 82%, p < 0.0001) and influenza (TAC/MMF 20%, TACmono 71%, p = 0.0092). Only 7% of TAC/MMF responded adequately to all three compared to 36% of TACmono (p = 0.080). Additionally, 40% of TAC/MMF responded inadequately to all three, whereas all TACmono patients responded adequately to at least one vaccination (p = 0.041). Lower SARS-CoV-2 vaccination antibody responses correlated with lower pneumococcal antibody vaccination responses (correlation coefficient: 0.41, p = 0.040). CONCLUSIONS: MMF on top of tacrolimus severely hampers antibody responses to a broad range of vaccinations.

Vitamin D and Aging: Central Role of Immunocompetence.

The pro-hormone vitamin D3 is an important modulator of both innate and adaptive immunity since its biologically active metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) regulates via the transcription factor VDR (vitamin D receptor) the epigenome and transcriptome of human immune cells and controls in this way the expression of hundreds of vitamin D target genes. Since the myeloid linage of hematopoiesis is epigenetically programmed by VDR in concert with the pioneer factors PU.1 (purine-rich box 1) and CEBPα (CCAAT/enhancer binding protein α), monocytes, macrophages, and dendritic cells are the most vitamin D-sensitive immune cell types. The central role of the immune system in various aging-related diseases suggests that immunocompetence describes not only the ability of an individual to resist pathogens and parasites but also to contest non-communicative diseases and the process of aging itself. In this review, we argue that the individual-specific responsiveness to vitamin D relates to a person's immunocompetence via the epigenetic programming function of VDR and its ligand 1,25(OH)2D3 during hematopoiesis as well as in the periphery. This may provide a mechanism explaining how vitamin D protects against major common diseases and, in parallel, promotes healthy aging.

Evaluation of Adjuvant Effect of Cytosine-Guanosine-Oligodeoxynucleotide in Meat-Type Chickens Coadministered In Ovo with Herpesvirus of Turkey Vaccine.

Herpesvirus of turkey (HVT) increases activation of T cells in 1-day-old chickens when administered in ovo. This study evaluated whether adding cytosine-guanosine oligodeoxynucleotides (CpG ODNs) to the HVT vaccine could enhance the adjuvant effect of HVT. We used a CpG ODN dose of 10 µg per egg. The experimental groups were (1) diluent-only control (sham), (2) HVT, (3) HVT+CpG ODN, (4) HVT+non-CpG ODN, (5) CpG ODN, and (6) non-CpG ODN control. Cellular response evaluation included measuring the frequencies of macrophages (KUL01+MHC-II+), gamma delta T cells (γδTCR+MHC-II+), CD4+, and CD8+ T cell subsets, including double-positive (DP) cells. In addition, CD4+ and CD8+ T cell activation was evaluated by measuring the cellular expression of major histocompatibility complex class II (MHC-II), CD44 or CD28 costimulatory molecules. An adjuvant effect was considered when HVT+CpG ODN, but not HVT+non CpG ODN, or CpG ODN, or non-CpG ODN, induced significantly increased effects on any of the immune parameters examined when compared with HVT. The findings showed that (1) HVT vaccination induced significantly higher frequencies of γδ+MHC-II+ and CD4+CD28+ T cells when compared with sham chickens. Frequencies of DP and CD4+CD28+ T cells in HVT-administered birds were significantly higher than those observed in the non-CpG ODN group. (2) Groups receiving HVT+CpG ODN or CpG ODN alone were found to have significantly increased frequencies of activated CD4+ and CD8+ T cells, when compared with HVT. Our results show that CpG ODN administration in ovo with or without HVT significantly increased frequencies of activated CD4+ and CD8+ T cells.

Meningitis criptocócica asociada a hidrocefalia en un paciente inmunocompetente / Cryptococcal meningitis associated with hydrocephalus in an immunocompetent patient

La meningitis criptocócica es una infección infrecuente y con alta morbimortalidad, cuya presentación en pacientes inmunocompetentes es excepcional. Presentamos el caso de un varón de 67 años que ingresó por un cuadro subagudo de alteración de la marcha e incontinencia urinaria. El examen neurológico reveló incapacidad para mantenerse en pie y deterioro de la memoria. Las pruebas de imagen craneales mostraron hidrocefalia tetraventricular obstructiva con áreas de gliosis en los pedúnculos cerebelosos. Se realizó tratamiento endoscópico de la hidrocefalia, con toma de muestras de líquido cefalorraquídeo en las que se observó crecimiento de Cryptococcus neoformans. El paciente mejoró con el tratamiento endoscópico y tras completar la terapia antifúngica intravenosa con anfotericina B liposomal y fluconazol durante diez semanas. La meningitis criptocócica en pacientes inmunocompetentes se trata con antifúngicos. En raras ocasiones se presenta con hidrocefalia, situación que requiere tratamiento quirúrgico mediante derivaciones del líquido cefalorraquídeo o técnicas endoscópicas. (AU)

Cryptococcal meningitis is an infrequent infection with high morbidity and mortality. Its presentation in immuno-competent patients is rare.We present the case of a 67-year-old male who was admitted for subacute symptoms of gait disturbance and urinary incontinence. Neurological examination revealed inability to stand and memory impairment. Cranial im-aging showed obstructive tetraventricular hydrocephalus with areas of gliosis in the cerebellar peduncles. Endo-scopic treatment of hydrocephalus was performed and cerebrospinal fluid samples taken revealing the growth of Cryptococcus neoformans. The patient improved with the endoscopic treatment and after completing intravenous antifungal therapy with liposomal amphotericin B and flu-conazole for ten weeks.Antifungals are used to treat cryptococcal meningitis in immunocompetent patients. On rare occasions, it presents with hydrocephalus, a situation that requires surgical treat-ment using cerebrospinal fluid diversions or endoscopic techniques. (AU)

Effects of time spent in pregnancy or brooding on immunocompetence.

Sexes of a species may show different characteristics beyond the differences in their sexual organs and such sexual dimorphism often occurs in the level of immune response when exposed to pathogens (immunocompetence). In general, females have increased longevity relative to males, which is associated with higher immunocompetence. However, males have higher immunocompetence in some species, such as pipefishes and seahorses. Experimental evidence suggests that this could be because males, rather than females, carry fertilized eggs to birth in these species. This observation suggests that an increase in immunocompetence may be related to the level of parental investment and not to a particular sex. We use state-dependent life-history theory to study optimal investment in offspring production relative to parent immunocompetence, varying the relative time that a parent spends in brooding or pregnancy within a breeding cycle. When offspring is dependent on a parent's survival for a large part of the breeding cycle, we predict higher investments in immunity and longer life expectancies.

Longitudinally extensive posterolateral myelitis revealing invasive CNS aspergillosis in an immunocompetent patient.

BACKGROUND: Fungal infections of the central nervous system usually affect immunocompromised patients. Primary Aspergillus myelitis has never been described. REPORT: A 45-year-old immunocompetent male with subacute paraplegia was treated for inflammatory myelitis before clinical deterioration requiring mechanical ventilation. Purulent meningitis preceded the formation of a paraspinal nodule biopsied by neurosurgery. Histopathological analysis revealed the presence of fungal hyphae, and polymerase chain reaction was positive for Aspergillus fumigatus. No cause of immunodeficiency was identified in this patient. DISCUSSION: Primary Aspergillus myelitis may be confused with inflammatory myelitis and should be considered even in the absence of apparent immunosuppression.

Response of broiler breeder pullets when fed hydrolyzed whole yeast from placement to 22 wk of age.

The study examined the effects of feeding broiler breeder pullets hydrolyzed whole yeast (HY) from hatch to 22 wk of age (WOA). A total of 524-day-old Ross 708 pullets were placed in floor pens (∼24 birds/pen) for the starter (0-4 WOA) and grower (5-18 WOA) phases, then transferred to the egg production facility and redistributed to ∼20 birds/pen for the prelay phase (19-22 WOA). Two diets were allocated to pens (0-18 WOA; n = 11) and (19-22 WOA; n-12). The diets were a control corn and soybean meal diet formulated to meet specifications and control plus 0.05% HY (HY). Birds had ad libitum access to feed in the first week and daily feed allocation based on pen BW from 2 WOA. Birds had free access to water throughout the trial. Body weight (BW) and uniformity (BW CV) were monitored. Boosters for infectious bronchitis and New Castle disease vaccines were administered at 18 WOA, and samples of pullets bled for antibody titer 5-day later. One pullet/pen was randomly selected, weighed, bled for plasma biochemistry, and necropsied for organ weights, ceca digesta for short-chain fatty acids (SCFA), and leg bones morphometry. In the starter and grower phases, birds fed HY were lighter and gained less (P < 0.05) than control birds. However, there were no diet effects (P > 0.05) on growth, the BW prelay phase, or BW uniformity throughout the trial. There were no (P > 0.05) diet effects on breast, gastrointestinal, liver and bursa weights, serum antibody titers, plasma biochemistry, SCFA and bone attributes. However, pullets fed HY had heavier (P = 0.047) spleen and tended to have lower (P = 0.080) plasma concentrations of aspartate aminotransferase (AST) relative to control pullets. In conclusion, the parameters assessed showed no negative consequences of feeding HY to broiler breeder pullets. However, effects on the spleen and plasma AST may indicate modest modulation of immunity and metabolism. The impact of the provision of HY during broiler breeder pullet phase on reproductive performance and chick quality should be investigated.

Sex-specific effects of immune challenges on green anole lizard metabolism.

Immune responses can increase survival, but they can also incur a variety of costs that may lead to phenotypic trade-offs. The nature of trade-offs between immune activity and other components of the phenotype can vary and depend on the type and magnitude of immune challenge, as well as the energetic costs of simultaneously expressing other traits. There may also be sex-specific differences in both immune activity and trade-offs, particularly with regard to energy expenditure that might differ between males and females during the breeding season. Females are generally expected to invest less in nonspecific immune responses compared to males due to differences in the allocation of resources to reproduction, which may lead to sex differences in the metabolic costs of immunity. We tested for sex-specific differences in metabolic costs of different types of immune challenges in Anolis carolinensis lizards, including lipopolysaccharide (LPS) injection and wounding. We also tested for differences in immune prioritization by measuring bacterial killing ability (BKA). We predicted males would show a greater increase in metabolism after immune challenges, with combined immune challenges eliciting the greatest response. Furthermore, we predicted that metabolic costs would result in decreased BKA. LPS injection increased the resting metabolic rate (RMR) of males but not females. Wounding did not affect RMR of either sex. However, there was an inverse relationship between BKA and wound healing in LPS-injected lizards, suggesting dynamic tradeoffs among metabolism and components of the immune system.

Painful Granulomatous Hashimoto Thyroiditis Uncovered Systemic Histoplasmosis.

Background. Granulomatous thyroiditis is usually viral and very rarely due to fungal infection. Fungal thyroiditis affects the severely immunocompromised and only rarely immunocompetent individuals. Case report. A 32-year-old man with known Hashimoto thyroiditis was consulted for a 1-week history of neck pain, dysphagia, cough, asthenia, loss of appetite, and night sweats. Imaging showed an enlarged right thyroid lobe. Laboratory studies confirmed hypothyroidism. He underwent a thyroid lobectomy. Microscopic examination showed granulomas in a background of Hashimoto thyroiditis. Silver stain revealed numerous yeasts consistent with Histoplasma. Subsequent serology was also positive. Further evaluations were negative for acquired or constitutional immunodeficiencies. He was started on oral itraconazole with resolution of all constitutional symptoms. Conclusions. We report a second case of concurrent Hashimoto and Histoplasma thyroiditis in an immunocompetent patient. Systemic manifestations of fungal infection are confounded by systemic symptoms of thyroid dysfunction. Fungal thyroiditis is a manifestation of systemic fungal infection requiring prolonged systemic therapy to prevent complications or fatal outcomes.

Plantar keratoderma-like crusted scabies in an immunocompetent infant after topical steroids.

A healthy 6-month-old girl presented with plantar keratoderma-like lesions unresponsive to topical corticosteroids. Nocturnal pruritus in 13 relatives, presence of burrows on clinical exam, and the positive scabies preparation led to the diagnosis of crusted scabies. She was successfully treated with topical and oral scabicides. Crusted scabies is a severe form of Sarcoptes scabiei infection uncommon in immunocompetent subjects, in whom previous corticosteroid use may favor its occurrence.

Ivermectin decreases parasite load, testosterone, and potentially antler length in a group of captive red deer males (Cervus elaphus).

Secondary sex traits (SSTs) can favour males in intra-sexual competition, allowing females to reliably assess their quality. They can also be connected to other aspects of fitness, such as resistance to parasites and pathogens, as parasites have negative effects on the development of SSTs. Antlers are one of the most recognizable examples of SSTs whose development is regulated by testosterone and reflects the actual condition of the bearer. Elevated testosterone can exaggerate the size of SSTs while impairing the function of the immune system ("The Immunocompetence Handicap Hypothesis") posing a trade-off between antler development and immune function. In this study, we experimentally manipulated the parasite load in captive red deer (Cervus elaphus) males with Ivermectin during antler development for two consecutive years. Expecting an inverse proportionality between parasite load and antler size, we hypothesized the treated deer to have larger antlers than the untreated ones. Our results showed that, following the immunocompetence handicap hypothesis, parasite load was positively associated with testosterone levels. However, the application of Ivermectin suppressed the parasite load of the treated animals but did not lead to the development of larger antlers. Instead, it significantly suppressed the concentration of testosterone in the treated animals, whilst the animals that had higher testosterone also had the highest parasite load. Our findings show that Ivermectin can potentially decrease the levels of testosterone and, consequently, antler size. These findings have important implications for the management of captive populations, especially in contexts where the development of large trophies is desired.