Invasive pneumococcal disease among human immunodeficiency virus-infected children, 1989-2006.

OBJECTIVE: The heptavalent pneumococcal conjugate vaccine (PCV7) has decreased the incidence of pediatric invasive pneumococcal disease (IPD) in the United States. Few data exist on the changing IPD incidence in HIV-infected children. METHODS: Diagnostic codes and clinical microbiology laboratory records identified cases of IPD from 1989 to 2006 in perinatally-infected children <18 years of age followed at an urban HIV clinic. IPD incidence was calculated and serotype distribution and antibiotic resistance were recorded. RESULTS: Two-hundred fifty-six patients were followed for 1756 person-years (PY). The sample was 59% female, 76% black, 14% white, and 8% Hispanic. Of 21 episodes of IPD (1200/100,000 PY), 17 (81%) were female. IPD cases had a median age of 6.3 years (interquartile range [IQR]: 2.3-9.9 years), median CD4% of 17% (IQR: 11-28%), and median CD4 count of 415 cells/mm (range, 2-1699 cells/mm). Bacteremia was the commonest form of IPD (19 episodes; 1080/100,000 PY). After HAART introduction in 1996, the incidence of IPD decreased 84% from 1862/100,000 PY in 1989-1995 to 292/100,000 PY in 1997-1999 (incidence rate ratio [IRR]: 0.16, P = 0.03). After PCV7 introduction in 2000, IPD incidence showed a nonsignificant increase from 292 of 100,000 PY in 1997-1999 to 860 of 100,000 PY in 2001-2006 (IRR: 2.94; P = 0.16). The percentages of IPD isolates nonsusceptible to penicillin and trimethoprim-sulfamethoxazole were 19% and 33%, respectively. Vaccine serotypes accounted for 38% of isolates, vaccine-related 14%, nonvaccine 33%, and the serotype was unknown in 14%. CONCLUSIONS: The incidence of IPD among perinatally HIV-infected children decreased after the introduction of HAART. Ongoing monitoring is required to determine the effect of PCV7 on IPD in this vulnerable population.

Molecular phylogenetic analysis of the avian malarial parasite Plasmodium (Novyella) juxtanucleare.

Plasmodium (Novyella) juxtanucleare is a widely distributed parasite that primarily infects chickens (Gallus gallus domesticus). All species of Novyella are characterized by very small schizonts, which in the case of P. juxtanucleare are always found juxtaposed to the erythrocyte nucleus, hence its name. Nearly complete small-subunit ribosomal RNA sequences have been obtained from 2 isolates of this species, and comparisons with other Plasmodium species have been made. Phylogenetic analysis reveals that this parasite is closely related to other avian-infecting Plasmodium species and that molecular relationships among the avian-infecting plasmodia do not correspond to their morphology-based subgeneric classifications.

A secreted protein from the human hookworm necator americanus binds selectively to NK cells and induces IFN-gamma production.

Parasitic helminths induce chronic infections in their hosts although, with most human helminthiases, protective immunity gradually develops with age or exposure of the host. One exception is infection with the human hookworm, Necator americanus, where virtually no protection ensues over time. Such observations suggest these parasites have developed unique mechanisms to evade host immunity, leading us to investigate the role of the excretory/secretory (ES) products of adult N. americanus in manipulating host immune responses. Specifically, we found that a protein(s) from ES products of adult N. americanus bound selectively to mouse and human NK cells. Moreover, incubation of purified NK cells with N. americanus ES products stimulated the production of augmented (4- to 30-fold) levels of IFN-gamma. This augmentation was dependent on the presence of both IL-2 and IL-12 and was endotoxin-independent. This is the first report of a pathogen protein that binds exclusively to NK cells and the first report of a nematode-derived product that induces abundant levels of cytokines from NK cells. Such an interaction could provide a means of cross-regulating deleterious Th2 immune responses in the host, thereby contributing to the long-term survival of N. americanus.