An epidemiological study of A. cantonensis in Jamaica subsequent to an outbreak of human cases of eosinophilic meningitis in 2000.

The infection status of angiostrongylosis in Jamaica was assessed in wild rats and molluscs in the 5 years following the major outbreak of eosinophilic meningitis (EM) in 2000. Parasitological analyses of 297 Rattus rattus and 140 Rattus norvegicus, and 777 terrestrial molluscs from all 14 Parishes on the island revealed Angiostrongylus cantonensis in 32·0% of the rats and in 12·5% of the molluscs. Multivariate analyses confirmed that A. cantonensis occurred significantly more frequently in R. rattus (Odds Ratio [OR] = 1·76), while mean infection intensity in R. rattus was also significantly higher (16·8) than R. norvegicus (11·3) (Mann-Whitney U-test: P = 0·01). Third-stage larvae of A. cantonensis were detected in 29% of 86 Pleurodonte spp.; in 20% of five Poteria spp.; in 18·7% of 369 Thelidomus asper; in 11% of 18 Sagda spp.; and in 6% of 24 veronicellid slugs. Most rodent infections occurred in Northeastern Jamaica (OR = 11·66), a region where infected molluscs were also abundant. Given the prevalence of A. cantonensis infection in rats has significantly increased since the 2000 outbreak, and that a survey of human infections revealed at least ten autochthonous cases in the last 15 years, angiostrongylosis persists as an important zoonosis in Jamaica.

Gastrointestinal helminths of wild hogs and their potential livestock and public health significance in Jamaica.

An investigation into the potential for transmission of gastrointestinal helminths from wild hogs to livestock and humans was prompted by concerns of recreational wild-hog hunting in the Caribbean region and the recent practice, by livestock farmers in Jamaica, of co-rearing wild and domesticated swine. Thirty-one wild hogs from the Hellshire Hills, a dry limestone forest in southern Jamaica, were necropsied during the period June 2004 to August 2006. Thirteen of the captured animals were male and 18 female. Four species of adult helminths were recovered from the gastrointestinal tracts of the wild hogs: Hyostrongylus rubidus (77%), Globocephalus urosubulatus (48%), Oesophagostomum dentatum (42%) and Macroacanthorhynchus hirudinaceus (77%). Two (6.2%), ten (32.2%) and 18 (58.0%) hogs harboured one, two and three species of helminths, respectively. Mean infection intensities varied from 8.1 for M. hirudinaceus, to 115.5 for O. dentatum. There was no association between any of the recovered helminths and sex of the host; however, a multivariate analysis indicated a positive association between the prevalence of G. urosubulatus and host age (odds ratio (OR) = 6.517). Domesticated hogs co-reared with wild hogs are potentially at risk of infection with all four helminths, while wild-hog hunters and pig farmers may be exposed to M. hirudinaceus.

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 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.

Mechanism of disinhibition after brain lesions.

Disinhibition syndromes, ranging from mildly inappropriate social behavior to full blown mania, may result from lesions to specific brain areas. Several studies in patients with closed head injuries, brain tumors, stroke lesions, and focal epilepsy have demonstrated a significant association between disinhibition syndromes and dysfunction of orbitofrontal and basotemporal cortices of the right hemisphere. Based on the phylogenetic origin of these cortical areas and their main connections with dorsal regions related to visuospatial functions, somatosensation, and spatial memory, the orbitofrontal and basotemporal cortices may selectively inhibit or release motor, instinctive, affective, and intellectual behaviors elaborated in the dorsal cortex. Thus, dysfunction of these heteromodal ventral brain areas may result in disinhibited behaviors.

Humoral responses in human strongyloidiasis: correlations with infection chronicity.

Strongyloides stercoralis L3-specific antibody isotype responses amongst individuals with known long-standing (28-46 years) infection were compared with those of 'young' (6-29 years of age) and 'old' (30-80 years of age) infected individuals from an endemic Jamaican population. Characterization of age-dependent isotype patterns in the endemic community showed that immunoglobulin (Ig) G1 responses were significantly inversely correlated with age. Additionally, a trend towards lower IgE levels in the older age group was observed. Comparison with responses amongst known chronically infected individuals showed that IgG1 and IgE levels were similar to those of the 'old' endemic group, but were significantly lower than those of the 'young' group. In contrast, IgA levels were similar in both endemic groups, but were elevated in chronically infected individuals. IgG4 levels were similar in all groups studied. These findings suggest that age correlates with infection chronicity in communities endemic for S. stercoralis, and that individuals acquire infection early in their lives and remain infected into adulthood. Early and sustained upregulation of IgG4 may facilitate the establishment of infection and, in combination with developing IgE hyporesponsiveness, may promote chronic asymptomatic strongyloidiasis. Conversely, upregulated IgA may be involved in controlling chronic infection levels which are reflected in reduced IgG1 production.

Short report: long-term serum antibody isotype responses to Strongyloides stercoralis filariform antigens in eight patients treated with ivermectin.

The enzyme-linked immunosorbant assay was used to investigate long-term changes in serum immunoglobulin G1 (IgG1), IgG4, IgE, and IgA against Strongyloides stercoralis phosphate-buffered saline-soluble filariform larval antigens in eight Jamaican patients treated with ivermectin. Patients were followed for periods of between 170 and 542 days. Based on repeated formalin-ether concentration and agar plate culture, all patients were found to be uninfected up to 18 months following chemotherapy. Generally, all antibody isotype levels decreased following treatment, although there was considerable heterogeneity among patients. In a single patient with hyperinfection, the decrease in IgG4 was marginal and may represent a treatment failure. Reduction in serum antibody isotype responses to S. stercoralis following treatment may be used to assess the effectiveness of ivermectin in treating endemic strongyloidiasis.

Parasitic infections associated with HIV/AIDS in the Caribbean.

This review article seeks to highlight the significance for the Caribbean of major parasitic infections associated with AIDS, encourage awareness of these opportunistic parasites, and promote familiarity with appropriate diagnostic techniques and their clinical relevance. Specific agents considered include Pneumocystis carinii; Toxoplasma gondii; the enteric coccidians Cryptosporidium spp., Isospora belli, and Cyclospora cayetanensis; the hemoflagellates Leishmania spp. and Trypanosoma cruzi; the fungi Histoplasma capsulatum and Cryptococcus neoformans; the nematode Strongyloides stercoralis; and the mite Sarcoptes scabiei. These disease agents can be divided into two groups, the immune-regulated "endogenous" parasites (the protozoans P. carinii and T. gondii, and possibly the roundworm S. stercoralis) and intracellular parasites (including the enteric coccidia, hemoflagellates, and fungi). Both in the Caribbean and elsewhere, the endogenous parasites (particularly P. carinii and T. gondii) are the most troublesome for AIDS patients, partly because they are likely to be transmitted and establish a benign immunoregulated presence early in the subject's life. Indeed, health management programs for AIDS patients often routinely include P. carinii prophylaxis, since nearly all such patients who survive long enough are expected to experience an episode of acute P. carinii infection. In contrast, there is no known epidemiologic association between AIDS and strongyloidiasis in the Caribbean, and the prevalence there of potentially opportunistic hemoflagellates such as Leishmania spp. and Trypanosoma cruzi is relatively low.

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.

Parasitic infections associated with HIV/AIDS in the Caribbean

This review article seeks to highlight the significance for the Caribbean of major parasitic infections associated with AIDS, encourage awareness of these opportunistic parasites, and promote familiarity with appropriate diagnostic techniques and their clinical relevance. Specific agents considered include Pneumocystis carinnii; Toxoplasma gondii; the enteric coccidians Cryptosporidium spp., Isospora belli, and Cyclospora cayetanensis; the hemoflagellates Leishmania spp. and Trypanosoma cruzi; the fungi Histoplasma capsulatum and Cryptococcus neoformans; the nematode Strongyloides stercoralis; and the mite Sarcoptes scabiei. These disease agents can be divided into two groups, the immune-regulated "endogenous" parasites (the protozoans P. carinii and T. gondii, and posibly the roundworm S. stercoralis) and intracellular parasites (including the enteric coccidia, hemoflagellates, and fungi). Both in the Caribbean and elsewhere, the endogenous parasites (particularly P. carinii and T. gondii) are the most troublesome for AIDS patients, partly because they are likely to be transmitted and establish a bening immunoregulated presence early in the subject's life. Indeed, health management programs for AIDS patients often routinely include P. carinii prophylaxis, since nearly all such patients who survive long enough are expected to experience an episode of acute P. carinii infection. In contrast, there is no known epidemiologic association between AIDS and strongyloidiasis in the Caribbean, and the prevalence there of potentially opportunistic hemoflagellates such as Leishmania spp. and Trypanosona cruzi is relatively low (AU)

Endoreplication in the ovary, testis, and intestine of Strongyloides stercoralis.

During development of the free-living adults of the human parasitic nematode Stronglyoides stercoralis, cells in certain tissues grow by endoreplication in which rounds of DNA replication occur without cell or nuclear division. The DNA content of individual nuclei was measured by microdensitometry of Feulgen-stained preparations. In females, some ovarian cells have up to 800 times the haploid DNA content (800C). In males, some cells of the testis have up to 100C. Intestinal cells in both sexes have up to 16C, whereas most other somatic cells have 2C.

Chromosome complement, gametogenesis, and development of Strongyloides stercoralis.

Gametogenesis and development were studied in free-living adults of the human parasitic nematode Strongyloides stercoralis. The diploid chromosome number is 6 in germ-line tissue of females and in embryos that will develop into parasitic females. Reproduction appears to be by meiotic parthenogenesis and pseudogamy, as in other species in the genus. Fecundity may be limited by the short lifespan of males. Newly hatched larvae contain about 500 cells, whereas adult females have about 840 somatic cells and a variable number of germ-line cells. The apical vegetative zones of both ovary and testis are occupied by cells with large amounts of DNA in their nuclei.

Prospective evaluation of enzyme-linked immunosorbent assay and immunoblot methods for the diagnosis of endemic Strongyloides stercoralis infection.

Recently described enzyme-linked immunosorbent assay (ELISA) and immunoblot methods for the detection of serum IgG against Strongyloides stercoralis larval antigens were prospectively evaluated for the diagnosis of endemic strongyloidiasis. A modification of the ELISA involved preincubation of sera with Onchocerca gutturosa phosphate-buffered saline-soluble extract to remove cross-reactivity with other helminths. The sensitivity of the ELISA increased from 80% to 85% following preincubation. Similarly, there was an increase in specificity from 94% to 97%. The IgG recognition of 41-, 31-, and 28-kD filariform larval components showed sensitivities of 100%, 85%, and 65%, respectively. Both the ELISA following incubation of sera with O. gutturosa extract and serum IgG reactivity to a 41-kD larval component using immunoblotting are sensitive and specific techniques for diagnosing endemic strongyloidiasis.

Specificity of changes in cerebral blood flow in patients with frontal lobe dementia.

Eight patients with a clinical diagnosis of probable Alzheimer's disease, eight patients with the clinical diagnosis of frontal lobe dementia, and eight controls were examined with single photon emission tomography (SPECT) using 99Tc-HMPAO. Patients with Alzheimer's disease and those with frontal lobe dementia met DSM-III-R criteria for mild dementia and were in the early stages of the illness. Compared with patients with Alzheimer's disease, the group with frontal lobe dementia had significantly lower blood flow in the frontal lobes (dorsolateral and orbital), the anterior temporal cortex, and the basal ganglia. Within the frontal lobe dementia group, blood flow was significantly lower in the orbital than in the dorsal frontal cortex, and in the anterior temporal than in the dorsal temporal cortex. The present study shows the specificity of changes in regional cerebral blood flow in the diagnosis of different types of dementia, and supports the importance of orbitofrontal, anterior temporal, and basal ganglia dysfunction in the production of the psychiatric syndrome of frontal lobe dementia.

Neuropsychological and neuroradiologic correlates of emotional prosody comprehension.

We examined a series of 59 patients with acute stroke lesions for the presence of comprehension emotional aprosody. Based on a standardized assessment of comprehension of emotional intonation, 29 patients (49%) showed emotional aprosody (17% "mild" aprosody [n = 10] and 32% "severe" aprosody [n = 19]). Patients with comprehension emotional aprosody showed a higher frequency of extinction on double-simultaneous stimulation, anosognosia, and deficits in facial emotion comprehension. Patients with comprehension emotional aprosody also showed a higher frequency of right-hemisphere lesions involving the basal ganglia and the temporoparietal cortex and more severe frontal and diencephalic atrophy. Comprehension emotional aprosody was not necessarily associated with poststroke depression (PSD) since patients with and without PSD showed similar impairments in emotional prosody comprehension.