Comparative neurovirulence of attenuated and non-attenuated strains of Venezuelan equine encephalitis virus in mice.

A candidate live-attenuated virus vaccine for protection against Venezuelan equine encephalitis (VEE) (designated V3526) was tested in mice to measure the magnitude, duration, and kinetics of virus replication in the blood and the central nervous system and its phenotypic stability after multiple passages in mice and cell culture. All results were compared to parallel experiments with parental virus and the existing VEE virus vaccine, TC-83. Maximum virus titers in the brains of V3526-inoculated mice were between 10- and 100-fold less than those observed in brains of mice inoculated intracranially (i.c.) with either the parental virus or TC-83. Neither V3526 nor TC-83 was lethal in BALB/c mice inoculated i.c.. However, mice inoculated with TC-83 developed acute symptoms lasting at least 14 days. In contrast, i.c. inoculation of TC-83 was uniformly lethal for C3H/HeN mice. V3526 was avirulent in both BALB/c and C3H/HeN mice after i.c. inoculation. The virulence characteristics of V3526 remained unchanged after five serial i.c. passages in mouse brains or after five cell culture passages. Finally, pathologic changes induced after i.c. inoculation of V3526 were consistently less severe and of shorter duration than those observed in TC-83-inoculated mice. Based on these results, V3526 is stable and appears to be significantly less neurovirulent in mice than TC-83.

Seroepidemiology of Helicobacter pylori infection in a Jamiaican community

We researched epidemiologic associations between environmental and demographic factors and prevalence of Helicobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n=346) were invited to participate following informed consent; the overall compliance rate was 58.9 percent. A commercial enzyme immunoassay (HM-CAP) was used to detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9 percent (n=202). Analysis of the independent variables revealed three major components. Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and, again large yard size. These three complexes explained 42.2 percent of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level (AU)

Seroepidemiology of Helicobacter pylori infection in a Jamaican community

We researched epidemiologic associations between environmental and demographic factors and prevalence of Heliobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n=346) were invited to participate following informed consent; the overall compliance rate ws 58.9 percent. A detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9 percent (n=202). Analysis of the independent variables revealed three major components: Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and again, large yard size. These three complexes explained 42.2 percent of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level. (AU)

The dermatologist in military operations.

The military dermatologist has a specific and significant role in military operations--in time of war as well as in peace. Many dermatologists are unfamiliar with the impact that our specialty and cutaneous disease has upon the ability of the military to fulfill the missions, duties, and responsibilities assigned by our government. This article highlights a few of the recent or ongoing types of military operations in which our specialty plays a prominent part.

Seroepidemiology of Helicobacter pylori infection in a Jamaican community.

We researched epidemiologic associations between environmental and demographic factors and prevalence of Helicobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n = 346) were invited to participate following informed consent; the overall compliance rate was 58.9%. A commercial enzyme immunoassay (HMáCAP) was used to detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9% (n = 202). Analysis of the independent variables revealed three major components: Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and, again, large yard size. These three complexes explained 42.2% of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level.

Comparative neurovirulence and tissue tropism of wild-type and attenuated strains of Venezuelan equine encephalitis virus administered by aerosol in C3H/HeN and BALB/c mice.

To assess the potential for aerosol administration of vaccines for Venezuelan equine encephalitis virus (VEE), we compared the neurovirulence and tissue tropism of the wild-type Trinidad donkey (TrD) strain to those of the attenuated TC83 and V3526 strains of VEE in mice. Six to 8-week-old female C3H/HeN and BALB/c mice were aerosol exposed to one of the three VEE strains. Three mice of each strain were euthanatized at different times and their tissues were processed and stained using hematoxylin and eosin, immunohistochemistry, and in situ hybridization. All three viral strains infected the brains of mice and induced encephalitis. TrD spread caudally from the olfactory bulbs to all regions of the brain, caused widespread necrotizing panencephalitis by day 5, and resulted in 100% mortality (geometric mean = 7 days) in both mouse strains. By comparison, TC83 relatively spared the caudal regions of the brain but still caused 100% mortality in the C3H/HeN mice (geometric mean = 12 days), yet it did not kill any BALB/c mice. V3526 infectivity of the brain was the most limited, mainly affecting the neocortex and diencephalon. This virus was not lethal in either mouse strain. The TrD strain also infected the olfactory neuroepithelium, local lymphoid tissues, teeth, and vomeronasal organs, whereas the affinity of TC83 and V3526 outside the brain was essentially limited to the olfactory neuroepithelium. Attenuated VEE strains administered to mice by aerosol have restricted tissue tropism as compared with wild-type virus; however, even attenuated strains can infect the brain and induce encephalitis.

Venezuelan equine encephalitis in BALB/c mice: kinetic analysis of central nervous system infection following aerosol or subcutaneous inoculation.

OBJECTIVE: To investigate the routes of entry of Venezuelan equine encephalitis (VEE) virus into the brain, we infected BALB/c mice with a virulent strain (V3000) by aerosol or subcutaneous inoculation. METHODS: Immunohistochemistry and in situ hybridization methods were used to detect VEE virus in tissues taken at daily intervals postinfection. RESULTS: In both groups, virus in the brain first appeared in olfactory regions. Aerosol exposure caused early massive infection of olfactory epithelium, which developed into bilaterally symmetrical infection of the olfactory nerves, olfactory bulbs, and lateral olfactory tracts by day 2 postinfection. After subcutaneous inoculation, VEE in the brain also appeared first in olfactory regions, but was not detected until day 3 postinfection. By day 4 postinfection, VEE viral infection had spread throughout the brain in both groups. Vascular endothelium and the choroid plexus remained uninfected during the entire study. CONCLUSIONS: Our findings suggest that VEE virus, whether given by aerosol or subcutaneously, first enters the brain through the olfactory tract.

Salmonella panama osteomyelitis in an otherwise healthy patient. A case report.

A 22-year-old man had Salmonella panama osteomyelitis of the left distal tibia. He had endured a period of untreated diarrhea without fever 6 years before. The osteomyelitis was treated successfully with surgical debridement followed by 9 weeks of oral cotrimoxazole 960 mg twice daily. Salmonella osteomyelitis is rare. Most cases occur in patients with sickle cell anemia. Other conditions of local or generalized immunosuppression are also risk factors, but none were established in this patient, nor was he a chronic carrier. In reviewing the literature, no case of Salmonella panama osteomyelitis in an otherwise healthy patient was found. Although the osteomyelitis in this patient was possibly secondary to Salmonella enteritis 6 years before, the authors believe that enteric Salmonella infections should not be treated with antibiotics unless the infection is accompanied by systemic symptoms. Otherwise, the risk of chronic carriership is substantially increased. In case of Salmonella panama osteomyelitis, surgical debridement is recommended as the main component of treatment, followed by a prolonged period of specific antibiotic therapy.

Age-prevalence and household clustering of Strongyloides stercoralis infection in Jamaica.

The epidemiology of Strongyloides stercoralis was studied in families of clinical (reference) cases and their neighbours at endemic foci in Jamaica. Thirteen foci were studied based on the place of residence of a reference case. For each household of a reference case, the 4 most proximal neighbourhood households (spatial controls) were included in the study. Out of 312 persons contacted 244 were followed up using questionnaires, stool examination and serology. Prevalence of infection based on stool examination was 3.5% and on ELISA 24.2%. Prevalence increased with age but was not related to gender. Reference cases were significantly older than the general study population. The prevalence of infection based on both serology and stool examination was significantly higher in reference than in neighbouring households (the reference cases, themselves, were not included in the analysis). Furthermore, prevalence of infection was highest among persons who shared a bedroom with a reference case and decreased significantly with increasing spatial separation. This is indicative of close contact transmission which has not been previously shown for a geohelminth, but which is common among microparasites.

Age-prevalence and household clustering of Strongyloides stercoralis infection in Jamaica

The epidemiology of Strongyloides stercoralis was studied in families of clinical (reference) cases and their neighbours at endemic foci in Jamaica. Thirteen foci were studied based on the place of residence of a reference case. For each household of a reference case, the 4 most proximal neighbourhood households (spatial controls) were included in the study. Out of 312 persons contacted 244 were followed up using questionaires, stool examimation and serology. Prevalence of infection based on based on stool examination was 3.5 percent and on ELISA 24.2 percent. Prevalence increased with age but was not related to gender. Reference cases were significantly older than the general study population. The prevalence of infection based on both serology and stool examination was significantly higher in referecne than in neighbouring households (the reference cases, themselves, were not included in the analysis). Furthermore, prevalence of infection was highest among persons who shared a bedroom with a reference case and decreased significantly with increasing spatial separation. This is indicative of close contact transmission which has not been previously shown for a geohelminth, but which is common among microparasites.(AU)

Age-prevalence profile and household clustering of cases of strongyloides infection at endemic foci at Jamaica - abstract

Strongyloides sterocalis infections were examined in families of clinical cases and also in those of their most proximal neighbours. Thirteen clinical cases in Kingston, Jamaica led to the identification of thirteen endemic foci. In addition to the clinical cases, 299 persons were contacted using questionnaires, stool examination and serology. Two hundred and thirty-one persons were fully compliant. The stool prevalence of S.sterocalis was 3.5 percent, while that based on ELISA was 24.2 percent (not including the 13 clinical cases). Both estimates of infection prevalence were significantly higher in the households of the clinical cases compared with the neighbours. The clinical cases were significantly older than the general study population. Furthermore, prevalence was highest among persons who shared a bedroom with a clinical case and decreased with spatial separation. These data strongly suggest that human strongyloides is a close-contact infection. This is likely to be facilitated by the direct phase of the parasite's life cycle and has significant implications for control of infections in endemic areas (AU)_

Immunoepidemiologic studies of Strongyloides stercoralis and human T lymphotropic virus type I infections in Jamaica.

Epidemiologic investigations of Strongyloides stercoralis and human T lymphotropic virus type I (HTLV-I) infections were conducted. Of 312 persons contacted, 209 (67%) provided blood and stool samples. Prevalences of S. stercoralis and HTLV-I antibodies were 26.8% and 8.1% (n = 198), respectively, and S. stercoralis larvae were detected in 4%. HTLV-I antibodies were significantly more common in persons positive for S. stercoralis larvae (10 [58.8%] of 17) compared with seropositive larva-negative (4 [8.9%] of 45) or seronegative persons (9 [6.2%] of 145) (P < .002). IgE levels increased with age in S. stercoralis-seropositive persons who were HTLV-I negative (P < .002). However, there was an age-related depression of serum IgE in HTLV-I-positive positive persons (P < .003) that was sufficient to annul the IgE level-raising effect of S. stercoralis seropositivity. The data provide evidence that HTLV-I infection is associated with increased frequency of larvae in the stool of S. stercoralis-infected persons and suggest that the mechanism may involve suppression of the IgE response.

Immunoepidemiologic studies of Strongyloides stercoralis and human T lymphoropic virus type I infection in Jamaica

Epidemilogic investigations of Strongyloides stercoralis and human T lymphotropic virus type I (HTLV-I) infections were conducted. Of 312 persons contacted, 209 (67 percent) provided blood and stool samples. Prevalences of S. stercoralis and HTLV-I antibodies were 26.8 percent and 8.1 percent (n = 198), respectively, and S. stercoralis larvae were detected in 4 percent. HTLV-I antibodies were significantly more common in persons positive for S. stercoralis larvae (10 [58.8 percent] of 17) compared with seropositive larvae-negative (4 [8.9 percent] of 45) or seronegative persons (9 [6.2 percent] of145) (P< .002). IgE levels increased with age in S. stercoralis-seropositive persons who were HTLV-I negative (P, .))2). However, there was an age-related depression of serum IgE in HTLV-I-positive persons (P < .003) that was sufficient to annul the IgE level-raising effect of S stercoralis seropositivity. The data provide evidence that HTLV-I infection is associated with increased frequency of larvae in the stool of S. stercoralis-infected persons and suggest that the mechanism may involve suppression of the IgE response (AU)

HTLV-1 infection - a risk factor for severe strongyloidiasis? - abstract

Epidemiological associations of Strongyloides stercoralis and Human T-Lymphotropic Virus Type-1 (HTLV-1) were investigated at eleven (11) foci endemic for strongyloidiasis in Jamaica. Each focus was identified on the basis of residency of a parasitologically-proved case of strongyloidiasis who presented at the University Hospital. Three hundred and twelve (312) persons were contacted, and blood and stool samples were collected for HTLV-1 and S. stercoralis serology and S. stercoralis coproculture, respectively. Overall compliance was 66.6 per cent. The prevalence of S. stercoralis in the pooled foci was 8.2 per cent including and 4.0 per cent excluding the hospital presenters, and for HTLV-1 it was 11.1 per cent and 8.1 per cent. Seroprevalence of S. stercoralis infection was 30 per cent and 26.8 per cent with and without the clinical cases, respectively. The prevalence of each infection was correlated with the age of the host (Spearman Rank Correlation, p<0.001). HTLV-1 was clustered in S. stercoralis larval shedders (58.8 per cent, n=17) compared with non-shedders (8.9 per cent, n=45) (Fisher's exact test, p<0.001), but particularly so among clinical cases 7 of whom (n=9) had HTLV-1 antibodies. The association was explained on the basis of age-related total serum IgE levels in HTLV-1/S. stercoralis infection cases. Individuals uninfected by S. stercoralis displayed a tendency for decreased IgE levels with age. This especially so in HTLV-1 carriers (ANCOVA: age * HTLV-1 interaction term t = 3.176, p<0.002). In marked contrast, S. stercoralis seropositive individuals had significantly elevated IgE titres in older persons compared with seronegative controls (ANCOVA: age * S. stercoralis interaction term t = 3.733, p<0.001). In persons seropositive for both HTLV-1 and S. stercoralis, however, the elevation of IgE levels previously observed in S. stercoralis positive individuals was completely subsumed by the negative influence of HTLV-1. It is suggested that impairment of host immunity by HTLV-1, and/or S. stercoralis in the presence of HTLV-1, exacerbates strongyloidiasis resulting in increased frequency of both larval shedding and parasite disease. Effect of S. stercoralis (S) and HTLV-1 (H) infection status on the host age/serum IgE association. This figure is designed to illustrate general trends; ungrouped data were used in statistical analyses (AU)

Interaction between HTLV-1 and Strongyloides stercoralis infection resulting in lowered IgE titres in Jamaica - abstract

In Japan, a positive association exists between the presence of serum antibodies to HTLV-1 and S. stercoralis. Also, it has been shown in Jamaica that coincidental HTLV-I infection may influence the outcome of treatment of S. stercoralis, or even underlie development of severe strongyloidiasis in some persons. However, the relationship between HTLV-I and S. stercoralis remains unclear. This paper highlights a hitherto unreported association between the occurrence of serum antibodies to HTLV-I, to S. stercoralis, and total serum IgE and strongyloidiasis in a Jamaican community. Blood and stool samples were collected from 67 persons from 6 geographical locations in Kingston. Sera were analysed for antibodies to S. stercoralis and HTLV-I, while stool samples were subjected to charcoal coproculture. As in Japan, individuals serologically positive for S. stercoralis tended to be infected more often with HTLV-I (33 per cent) than seronegative individuals (15 per cent), but the difference was not significant (two-tailed Fisher's exact test; P = 0.15). However, parasitologically-proved strongyloidiasis and HTLV-I seroconversion were strongly associated; while occurrence of HTLV-I was 67 per cent in individuals whose stool contained S. stercoralis larvae, it was only 15 per cent in their parasitologically negative counterparts (two-tailed Fisher's exact test; P = 0.01). Analyses strongly suggest that serological status for S. stercoralis HTLV-I affect IgE titres interaction term, F = 3.54; P = 0.06). IgE titres were lower in HTLV-I seropositive than seronegative individuals in both groups with and without S. stercoralis antibodies (HTLV-I main effect, F = 11.13; P = 0.002), but more strongly so in the former group (Table). S. stercoralis infection appeared to elevate reagin levels in some individuals in the HTLV-I negative group (n=13) (one-way ANOVA, F = 2.09; P - 0.15). In contrast, however, serum IgE titres were depressed in the group (n-5) with HTLV-I and concomitant S. stercoralis infection to levels perhaps even lower than those seen in HTLV-I individuals who did not have S. stercoralis (one-way ANOVA, F = 2.39; p = 0.15). Thus, it appears that HTLV-I and S. stercoralis operate synergistically to effect a significant reduction in IgE serum antibodies in infected individuals. If expressed at the level of the intestinal mucosa, this may permit increased rates of autoinfection of the parasite and result in correspondingly greater worm loads and patient morbidity. Lower levels of IgE antibodies against S. stercoralis are known to be associated with disseminated disease (AU)