Hepatosplenic Alpha-Beta T-Cell Lymphoma: A Challenging Diagnostic Entity

Hepatosplenic T-cell lymphoma (HSTCL) is rare and clinically very aggressive T-cell lymphoma. The majority of cases harbor γδ T-cell receptors (TCRs); however, in some even rarer cases, tumor cells harbor αβ TCR. Recent studies suggest that αβ cases may have distinct morphological characteristics and demonstrate an even more aggressive course. In this case report, we demonstrated that in line with previous findings, αβ case of HSTCL had hemolytic presentation, demonstrated a very aggressive clinical course, and was unrelated to immunosuppression. Morphologically, tumor cells demonstrated diffuse growth pattern, blastoid morphology, and were CD8+ positive on the background of CD4+ small to medium reactive T cells. Additionally, the liver tumor cells demonstrated periportal localization, and in bone marrow, evidence of emperipolesis was noted. The latter finding may significantly contribute to pancytopenia characteristic, all types of HSTCL. Those unusual morphologic and clinical characteristics make diagnosis of this rare subtype of rare disease very challenging. More case analysis is required to establish whether αβ/γδ HSTCL are prognostically or morphologically significantly distinct entities.

Predictions of malaria vector distribution in Belize based on multispectral satellite data

Use of multispectral satellite data to predict arthropod-borne disease trouble spots is dependent on clear understandings of environmental factors that determine the presence of disease vectors. A blind test of remote sensing-based predictions for the spatial distribution of a malaria vector, Anopheles pseudopunctipennis, was conducted as a follow-up to two years of studies on vector-environmental relationships in Belize. Four of eight sites that were predicted to be high probability locations for presence of An. pseudopunctipennis were positive and all low probability sites (0 of 12) were negative. The absence of An. pseudopunctipennis at four high probability locations probably reflects the low densities that seem to characterize field populations of this species, i.e., the population densities were below the threshold of our sampling effort. Another important malaria vector, An. darlingi, was also present at all high probability sites and absent at all low probability sites. Anopheles darlingi, like An. pseudopunctipennis, is a riverine species. Prior to these collections at ecologically defined locations, this species was last detected in Belize in 1946.

Predictions of adult Anopheles albimanus densities in villages based on distances to remotely sensed larval habitats

Remote sensing is particularly helpful for assessing the location and extent of vegetation formations, such as herbaceous wetlands, that are difficult to examine on the ground. Marshes that are sparsely populated with emergent macrophytes and dense cyanobacterial mats have previously been identified as very productive Anopheles albimanus larval habitats. This type of habitat was detectable on a classified multispectral System Probatoire d'Observation de la Terre image of northern Belize as a mixture of two isoclasses. A similar spectral signature is characteristic for vegetation of river margins consisting of aquatic grasses and water hyacinth, which constitutes another productive larval habitat. Based on the distance between human settlements (sites) of various sizes and the nearest marsh/river exhibiting this particular class combination, we selected two groups of sites: those located closer than 500 m and those located more than 1,500 m from such habitats. Based on previous adult collections near larval habitats, we defined a landing rate of 0.5 mosquitoes/human/min from 6:30 PM to 8:00 PM as the threshold for high (> or = 0.5 mosquitoes/human/min) versus low (< 0.5 mosquitoes/human/min) densities of An. albimanus. Sites located less than 500 m from the habitat were predicted as having values higher than this threshold, while lower values were predicted for sites located greater than 1,500 m from the habitat. Predictions were verified by collections of mosquitoes landing on humans. The predictions were 100% accurate for sites in the > 1,500-m category and 89% accurate for sites in the < 500-m category.

Preliminary observations on the changing roles of malaria vectors in southern Belize

A survey for larval and adult Anopheles mosquitoes was conducted in Toledo District of southern Belize during August-September 1992. We surveyed for larvae in 145 habitats and conducted paired indoor-outdoor collections of adult mosquitoes landing on humans at 6 houses. In 1940-41, Kumm and Ram reported Anopheles darlingi females to be the most common Anopheles mosquitoes inside houses and reported no specimens of Anopheles vestitipennis in southern Belize. In our 1992 survey we found no An. darlingi mosquitoes either as adults or larvae. More An. vestitipennis females were captured indoors than outdoors, whereas most Anopheles albimanus and Anopheles apicimacula females were captured outdoors. All 3 species were represented occasionally in 145 collections of larvae from diverse habitats. Anopheles vestitipennis now appears to be a potentially important vector of malaria during the wet season in Toledo District.

Relationship of iron administration to susceptibility of newborn pigs to enterotoxic colibacillosis

To determine whether supplemental iron (Fe) administration to newborn pigs reared in concrete pens not only prevents anemia, but renders the pigs more susceptible to Escherichia coli-induced diarrheal disease, pigs were given a large or a small dose of Fe IM or orally before or after challenge exposure with E coli. The controls were challenge-exposed pigs not given Fe and pigs not challenge exposed (Fe-treated and nontreated groups). Although the mortality of the pigs challenge exposed with E coli and administered a large oral dose of Fe shortly after birth was greater than that of the challenge-exposed pigs given no Fe, differences in mortality were not noted between any of the groups tested when the Fe was injected IM. The Fe-treated survivors had severe diarrhea (oral Fe administration) or mild diarrhea (IM Fe administration) for longer periods than did the nontreated survivors. All challenge-exposed pigs treated with a large dose of Fe gained less weight than the nontreated pigs during the diarrheal period and for several days thereafter. Beyond this time period, the weight gain of the Fe-treated pigs was substantially greater than that of their nontreated littermates; the weight gain of the pigs given a small dose of Fe was intermediate. Hemoglobin and hematocrit values of the pigs shortly after birth and weekly thereafter revealed that within 2 weeks, both sets of values from the pigs treated with a large dose of Fe were within acceptable laboratory limits and substantially greater than the values obtained for the nontreated pigs, which were severely anemic.