Effects of cnidarian biofouling on salmon gill health and development of amoebic gill disease.

This study examines the potential implications of biofouling management on the development of an infectious disease in Norwegian farmed salmon. The hydroid Ectopleura larynx frequently colonises cage nets at high densities (thousands of colonies per m2) and is released into the water during regular in-situ net cleaning. Contact with the hydroids' nematocysts has the potential to cause irritation and pathological damage to salmon gills. Amoebic gill disease (AGD), caused by the amoeba Paramoeba perurans, is an increasingly international health challenge in Atlantic salmon farming. AGD often occurs concomitantly with other agents of gill disease. This study used laboratory challenge trials to: (1) characterise the gill pathology resulting from the exposure of salmon to hydroids, and (2) investigate if such exposure can predispose the fish to secondary infections-using P. perurans as an example. Salmon in tanks were exposed either to freshly 'shredded' hydroids resembling waste material from net cleaning, or to authentic concentrations of free-living P. perurans, or first to 'shredded' hydroids and then to P. perurans. Gill health (AGD gill scores, non-specific gill scores, lamellar thrombi, epithelial hyperplasia) was monitored over 5 weeks and compared to an untreated control group. Nematocysts of E. larynx contained in cleaning waste remained active following high-pressure cleaning, resulting in higher non-specific gill scores in salmon up to 1 day after exposure to hydroids. Higher average numbers of gill lamellar thrombi occurred in fish up to 7 days after exposure to hydroids. However, gill lesions caused by hydroids did not affect the infection rates of P. perurans or the disease progression of AGD. This study discusses the negative impacts hydroids and current net cleaning practices can have on gill health and welfare of farmed salmon, highlights existing knowledge gaps and reiterates the need for alternative approaches to net cleaning.

Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water.

BACKGROUND: Naegleria fowleri is a climate-sensitive, thermophilic ameba found in the environment, including warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri-containing water enters the nose, typically during swimming, and N. fowleri migrates to the brain via the olfactory nerve. In 2011, 2 adults died in Louisiana hospitals of infectious meningoencephalitis after brief illnesses. METHODS: Clinical and environmental testing and case investigations were initiated to determine the cause of death and to identify the exposures. RESULTS: Both patients had diagnoses of PAM. Their only reported water exposures were tap water used for household activities, including regular sinus irrigation with neti pots. Water samples, tap swab samples, and neti pots were collected from both households and tested; N. fowleri were identified in water samples from both homes. CONCLUSIONS: These are the first reported PAM cases in the United States associated with the presence of N. fowleri in household plumbing served by treated municipal water supplies and the first reports of PAM potentially associated with the use of a nasal irrigation device. These cases occurred in the context of an expanding geographic range for PAM beyond southern tier states with recent case reports from Minnesota, Kansas, and Virginia. These infections introduce an additional consideration for physicians recommending nasal irrigation and demonstrate the importance of using appropriate water (distilled, boiled, filtered) for nasal irrigation. Furthermore, the changing epidemiology of PAM highlights the importance of raising awareness about this disease among physicians treating persons showing meningitislike symptoms.

Acanthamoeba meningoencephalitis presenting as neuropsychiatric lupus in a pediatric patient.

We present the case of a 16-year-old patient with systemic lupus erythematosus who presented with altered mental status and regressive behaviour. She was worked up and empirically treated for common and opportunistic infectious agents. All work-up was negative and after an extensive course of antibiotics she was treated for neuropsychiatric lupus with cytoxan. She initially responded, but this was short-lived and she eventually became comatose and passed away. On brain biopsy she was found to have numerous trophozoites with round nucleus, prominent nucleolus and thin nuclear membrane. Methenamine silver stain showed encysted amoeba, corresponding with a diagnosis of acanthamoeba meningoencephalitis. Making the diagnosis of acanthamoeba meningoencephalitis requires a high degree of suspicion. Specific serum antibodies may not be a reliable measure in immunocompromised patients and trophozoites in CSF can be confused with monocytes. Brain biopsy may be required to make a definitive diagnosis. It is important for clinicians treating immunocompromised patients to keep this agent in mind in an immunocompromised patient with neurological manifestations. Acanthamoeba infections have only been reported in a small handful of patients and, to our knowledge, this is the first reported case in the United States.

Los modelos experimentales in vivo en la amibiasis / In vivo experimental models of amebiasis

La utilización de los modelos experimentales in vivo en la amibiasis, ha proporcionado información importante sobre los mecanismos involucrados en la relación huésped-parásito que determinan la producción de la enfermedad. En el laboratorio se han utilizado varios roedores para estudiar la amibiasis intestinal y la hepática. Para la primera, el modelo del "asa cecal lavada y cerrada" en el cobayo y el hámster ha sido útil para el análisis de las etapas tempranas del daño a la mucosa. También se ha logrado producir lesiones tempranas intestinales en el jerbo por inoculación intracecal de amibas en cultivo monoxénico. Para los modelos de amibiasis hepática, se han utilizado el hámster y el jerbo como animales susceptibles, y la rata y el cobayo como animales resistentes. El análisis morfológico de las lesiones hepáticas en losanimales susceptibles mostró que las células inflamatorias del huésped participan en la producción del daño hepático. La resistencia a la producción de absceso hepático amibiano en ratas y cobayos se debe en parte a los leucocitos polimorfonucleares en la rata y los macrófagos en el cobayo. La completa caracterización y estandarización de los diversos modelos de amibiasis en roedores constitutyen las bases para otros estudios biomédicos de importancia para el control de la enfermedad

Amoebic disease precipitated by corticosteroids prescribed for tuberculous pleural effusions.

One case of ameobic abscess of the liver and one case of amoebic dysentery are described in two patients who were prescribed corticosteroids as part of the intreatment for tuberculous pleural effusion. In both cases routine stool examinations prior to steroid therapy were negative for cysts or trophozoites of E. histolytica.