Histopathology of Antarctic krill, Euphausia superba, bearing black spots.

Small black spots have been noticed on the cephalothorax of Antarctic krill, Euphausia superba, since January, 2001. To study the nature of the black spots, the krill were sampled in the winter of 2003, 2006, and 2007 in the South Georgia region, the Antarctic Ocean. Histological observations revealed that the black spots were melanized nodules that were composed of hemocytes surrounding either bacteria or amorphous material. In the 2007 samples, 42% of the krill had melanized nodules. Most of the nodules had an opening on the body surface of the krill. A single melanized nodule often contained more than one type of morphologically distinct bacterial cell. Three bacteria were isolated from these black spots, and classified into either Psychrobacter or Pseudoalteromonas based on the sequences of 16S rRNA genes. More than three bacterial species or strains were also confirmed by in situ hybridization for 16S rRNA. The melanized nodules were almost always accompanied by a mass of atypical, large heteromorphic cells, which were not observed in apparently healthy krill. Unidentified parasites were observed in some of the krill that had melanized nodules. These parasites were directly surrounded by the large heteromorphic cells. Histological observations suggested that these heteromorphic cells were attacking the parasites. These results suggest the possibility that the krill had been initially affected by parasite infections, and the parasitized spots were secondary infected by environmental bacteria after the parasites had escaped from the host body.

The clinical importance of demodex folliculorum presenting with nonspecific facial signs and symptoms.

Demodex folliculorum (D. folliculorum), found in the pilosebaceous unit, is the most common ectoparasite of humans. Various clinical forms such as pustular folliculitis, papulopustular scalp eruptions, perioral dermatitis, and blepharitis have been defined, although in general, the disease has been classified into three main groups as "pityriasis folliculitis", "rosacea-like demodicidosis", and granulomatous rosacea-like "demodicidosis gravis". Our aim was to test for the presence of D. folliculorum in pathogenic numbers in patients who came to our clinic with non-specific symptoms such as facial itching with or without erythema, seborrheic dermatitis-like or perioral dermatitis-like lesions, papulopustular lesions, and an acneiform clinical appearance without telengiectasia or flushing. Twenty-eight (87.5%) female and 4 male (12.5%), patients and 33 age-and-sex matched healthy subjects enrolled in this study. D. folliculorum was sought in the lesion sites using the non-invasive method known as the Standardised Skin Surface Biopsy (SSSB). The discovery of more than five parasites in an area of 1 cm2, was evaluated as pathogenic. For treatment, 5% permethrine cream was applied twice daily for 15 to 30 days. The clinical symptoms of the patients were classified into clinical groups and evaluated as facial itching in 2 (6.3%), nonspecific erythema and itching in 21 (65.6%), erythema and pityriasiform squamous lesions in 3 (9.4%), acneiform in 3 (9.4%), papulopustular lesions in 1 (3.1%), granulomatous rosacea-like in 1 (3.1%), and perioral dermatitis-like symptoms in 1 (3.3%), D. folliculorum density was determined as 5>D/cm2 in all clinical lesions. A significant clinical healing and density of D. folliculorum at <=5 D/cm2 was determined in all but two patients after treatment. We consider that D. folliculorum presentation with different symptoms and signs than classical forms is not rare. For this reason, we suggest that it is useful to test for D. folliculorum in patients with non-classical presentations like facial itching, itching accompanied by non-specific erythema, itching and non-specific pityriasiform squamous lesions, and acneiform lesions.

Dermatitis due to larvae of a soil nematode, Pelodera strongyloides.

A 6-month-old infant girl was seen because of failure to thrive and hyperpigmented papulonodules on the lower abdomen and thighs. Results of skin biopsy demonstrated dauer larvae of a soil nematode, Pelodera strongyloides, in the dermis. This is the second documented episode of human dermatitis due to this nematode, which more often invades the skin of dogs, cattle, horses, and sheep.