Hemophagocytic lymphohistiocytosis (HLH) is an unusual syndrome characterized by fever, splenomegaly, jaundice, and the pathologic finding of hemophagocytosis (phagocytosis by macrophages of erythrocytes, leukocytes, platelets, and their precursors) in bone marrow and other tissues. HLH may be diagnosed in association with malignant, genetic, or autoimmune diseases but is also prominently linked with Epstein-Barr (EBV) virus infection. Hyperproduction of cytokines, including interferon-gamma and tumor necrosis factor-alpha, by EBV- infected T lymphocytes may play a role in the pathogenesis of HLH. EBV-associated HLH may mimic T-cell lymphoma and is treated with cytotoxic chemotherapy, while hemophagocytic syndromes associated with nonviral pathogens often respond to treatment of the underlying infection.

/pdf/hemophagocytic-syndromes-and-infection-2aj9a8bz14.pdf

Hemophagocytic syndromes and infection.

Familial hemophagocytic lymphohistiocytosis (FHL) is probably a genetically transmitted disease affecting infants and very young children. Cardinal symptoms are fever, hepatosplenomegaly, and pancytopenia. Frequently meningeal involvement is seen, manifested by neurologic symptoms and a lymphohistocytic pleocytosis with increased protein levels in the cerebrospinal fluid. Characteristic laboratory findings in FHL are hypertriglyceridemia and hypofibrinogenemia, which are reversible with treatment. The disease has been rapidly fatal in most patients, but recently longterm remissions have been achieved with cytotoxic agents.

https://www.hemonc.theclinics.com/article/S0889-8588(05)70520-7/pdf

Familial hemophagocytic lymphohistiocytosis

Bright light effects on body temperature, alertness, EEG and behavior.

Publisher Summary Ticks are highly specialized obligate parasites of a wide variety of terrestrial and flying vertebrates and a few marine snakes and lizards. During the one to several long periods that most tick species spend off the host and on the ground, their survival depends on a delicate interplay among physiological and structural properties and functions and ecological factors. Thus, tick-host and tick-environmental factors are both of paramount importance in understanding the role of the individual tick species as a parasite and a vector. This chapter focuses on ticks and tick-borne diseases and reviews tick structures and physiology. It discusses the tick cuticle; humidity relationships and water balance; sensory basis of feeding behavior, attachment, and feeding (role of the mouthparts, feeding apparatus, salivary gland secretions, and host response); immunological basis of host resistance; blood digestion; ion and water balance during feeding and mechanisms of excretion; reproduction (sperm development, cytogenetics, oogenesis, and oviposition); structure and functions of the circulatory, nervous, and neuroendocrine systems; endocrine mechanisms (effects of insect hormones and their mimics on development and reproduction); pheromone mechanisms; and diapause and biological rhythms.

Argasid and nuttalliellid ticks as parasites and vectors

Publisher Summary This chapter is concerned with the immunological concepts in leprosy leading to a discussion of the analogous states now recognized in other infectious diseases. The typical nodular form of leprosy, associated with massive infiltration of the tissues with histiocytcs packed with colonies of mycobacteria and an apparent inability of the body to eliminate the organism is one of the two main types of the disease. The other, the anesthetic or maculoanesthetic form, is associated with the peripheral nerve damage with or without cutaneous lesions. Here, the microorganisms may be scanty or difficult to demonstrate, and the skin lesions may come to resemble those in lupus vulgaris. Tuberculoid has, therefore, been used as a generic term to describe the second form of the disease; the nodular form of leprosy is now referred to a lepronzatous. Leishmaniasis is a spectral disease similar to leprosy, in which the clinical features of the disease depend on the cell-mediated immunity (CMI) response of the host toward the parasite. When this response is deficient, diffuse cutaneous leishmaniasis (DCL) results. The possible reasons for such deficiency in CMI is also discussed with their nature and specificity of the defect.

Immunological phenomena in leprosy and related diseases.

A 22-year-old man with fever, hepato-splenomegaly and severe pancytopenia is described in whom the histologic features of the spleen, liver and lymph nodes were consistent with malignant histiocytosis. Characteristic Leishman-Donovan bodies were demonstrated on a bone marrow aspirate, and the diagnosis of visceral leishmaniasis was confirmed by culturing the flagellated forms of the pathogen, and by an excellent response to sodium stibogluconate. In view of the similarity in clinical and histologic appearance, visceral leishmaniasis must be considered in the differential diagnosis of malignant histiocytosis in geographic areas where leishmaniasis is still endemic.

Systemic leishmaniasis mimicking malignant histiocytosis.

SINCE 1963 there has been an increase in the number of clinical cases of cutaneous leishmaniasis in Israel. Katzenellenbogen and Confino1 reported in 1964 an outbreak at Yotvata, an agricultural settlement in the Southern Negev, about 25 miles north of Eilat. This outbreak started about 5 yr after the establishment of the settlement on virgin soil, and thirty-three out of one hundred and fifty inhabitants were affected. An earlier report2 recorded an outbreak at Revivim, another desert settlement, where the first cases were noted 3 yr after its establishment. In neither locality had an attempt been made to trap gerbils—although numerous burrows were seen.

Identification of Leishmania Species isolated from Rodents in Israel

IT is the accepted view that parasites belonging to the suborder Piroplasmidae Wenyon, 1926, are exclusively transmitted by “hard” ticks belonging to the family Ixodidae Murray1,2 Most piroplasms of domestic animals have more than one Ixodid vector In the laboratory, small mammal piroplasms belonging to the genera Babesia Starcovici, 1893, and Nuttallia Franca, 1910, are used as models for the diseases caused by piroplasms of domestic animals This research, however, suffers from the drawback that the parasites cannot be biologically transmitted, except in two cases Thus, Babesia rodhaini Van den Berghe, Vincke, Chardome and Van den Bulcke, 1950, a rodent piroplasm very commonly used in laboratory investigations, has no known vector; nor has Babesia hylomysci Bafort, Tirnperman and Molineux, 1970 The two small mammal piroplasms of which the vectors are known are Nuttallia microti Coles, 1914, and Nuttallia danii Tsur, Hadani and Pipano, 1960 (and the probably identical N tadzhikistanica (Krylov and Zanina, 1963), Krylov, 1964) The vectors of these piroplasms are Ixodes trianguliceps3 Birula, 1895, for the former, and three species of Hyalomma and two species of Rhipicephalus4 for the latter All of these vectors belong to the Ixodidae

Arnon E. Gunders

Papers

Systemic leishmaniasis mimicking malignant histiocytosis.

Identification of Leishmania Species isolated from Rodents in Israel

Transmission of Mammalian Piroplasm by an Argasid Tick