A case of atopic dermatitis caused by Ascaris lumbricoides infection

Feline heartworm disease and environmental allergens hypersensitivity: is there a link?

BACKGROUND

Cats can be infected by Dirofilaria immitis, the causative agent of heartworm disease, characterized by respiratory signs, airway hyperreactivity, remodelling and inflammation. Allergy is a multifactorial pathology, and the role of a number of helminth parasites in the development of allergies in humans and other species has been demonstrated in many studies. The aim of the present study was to verify whether cats seropositive for D. immitis present hypersensitivity to some environmental allergens.

METHODS

Blood samples were collected from 120 cats and tested for the presence of specific immunoglobulin G antibodies against D. immitis and for hypersensitivity to 20 allergens, using commercial allergen test kits.

RESULTS

Of the 120 cats tested, 72 (60.0%) were seropositive for anti-D. immitis IgG and 55 (45.8%) showed clinical signs of heartworm disease of a respiratory nature. The results of testing with the allergen kits showed that 50.8% of cats were seropositive for ≥ 1 allergens, with the most common allergens being Dermatophagoides farinae (25.8%), Dermatophagoides pteronyssinus (20.0%), Malassezia (17.5%) and Ctenocephalides felis (14.2%). The prevalence of allergies was significantly higher-by almost threefold-in cats seropositive for D. immitis (68.1% vs. 25%). There were no significant differences between the prevalence of allergic cats and presence/absence of symptoms, and the results confirmed that symptoms were not a decisive factor for the presence of allergies. The risk for developing allergies was 6.3-fold higher in cats seropositive for D. immitis than in cats that were seronegative, confirming that seropositivity for D. immitis is a risk factor.

CONCLUSIONS

Cats with confirmed heartworm can develop serious respiratory signs, potentially leading to progression to permanent lung injury and predisposing cats to hyperresponsive airway disease. Previous studies have shown that seropositivity for D. immitis and Wolbachia is related to the presence of bronchoconstriction and bronchospasm in the affected cat. The results support the suspicion that contact with D. immitis may be a risk factor for the presence of allergies.

Parasite-Induced Th2 Polarization—An Unusual Cause of Paediatric Hepatic Abscess

Liver abscess (LA) is a serious infectious disease, but is relatively rare in the paediatric population, especially in developed countries. Mostly, hepatic abscesses are pyogenic, caused by Staphylococcus aureus, while in extremely rare cases can be caused by parasites, such as Ascaris lumbricoides. Antimicrobial therapy and percutaneous drainage are the treatments of choice, lowering the mortality caused by this infection. We report a case of a 3-year-old girl admitted to the hospital for abdominal pain and a low-grade fever, with abdominal ultrasonography revealing a hepatic lesion. Initial laboratory tests showed moderate anaemia, thrombocytosis, eosinophilia, high inflammatory markers, and normal liver function. A computed tomography scan revealed two liver abscesses located subdiaphragmatically, and a high immunoglobulin E (IgE) value (22,300 U/mL). After excluding other possible etiologies, the patient was tested for parasitic infections. IgE for Ascaris lumbricoides came slightly higher. In addition to empirical antibiotic treatment, the patient received albendazole and made an uneventful recovery, with the full remission of the abscesses and without the need for drainage. In certain cases, parasites such as Ascaris lumbricoides are capable of inducing a T helper 2 (Th2) dominated immune response, predisposing the host to eosinophilia, hyperIgE, and increased susceptibility to bacterial infections. Early diagnosis and treatment in these cases may lead to less invasive therapy options in order to obtain a full recovery. To the best of our knowledge, this is the only reported case in the literature of a paediatric patient with parasite-induced liver abscesses, with extremely high IgE values, minimal symptomatology, that made a fast, full recovery without the need of drainage.

Immunological underpinnings of Ascaris infection, reinfection and co-infection and their associated co-morbidities

Human ascariasis is the most common and prevalent neglected tropical disease and is estimated that ~819 million people are infected around the globe, accounting for 0.861 million years of disability-adjusted life years in 2017. Even with the existence of highly effective drugs, the constant presence of infective parasite eggs in the environment contribute to a high reinfection rate after treatment. Due to its high prevalence and broad geographic distribution Ascaris infection is associated with a variety of co-morbidities and co-infections. Here, we provide data from both experimental models and humans studies that illustrate how complex is the interaction of Ascaris with the host immune system, especially, in the context of reinfections, co-infections and associated co-morbidities.