Workshop on research priorities for management and treatment of angiostrongyliasis(1).

In a concluding session of the workshop, the participants developed a list of 115 research and outreach needs, outlining the top 5-7 needs in each of 8 areas (Table). For complete information, including presenter details and abstracts, visit the workshop website at www.hawaii.edu/cowielab/Angio%20website%20home.htm.

Population distribution and zoonotic potential of gastrointestinal helminths of wild rats Rattus rattus and R. norvegicus from Jamaica.

The population distribution and zoonotic potential of gastrointestinal helminths in a naturally infected population of wild rats (Rattus rattus and Rattus norvegicus) in Jamaica are described. One hundred and thirty (29.7%) of 437 rats captured in the study were infected: 104 (35%) of 297 R. rattus compared with 26 (18.6%) of 140 R. norvegicus. Nine species of gastrointestinal helminths were recovered: Raillietina sp. (0.2%), Trichuris sp. (0.2%), Rictularia sp. (0.7%), Syphacia obvelata (1.1%), Strongyloides ratti (1.4%), Hymenolepis diminuta (3.8%), Protospirura muricola (4.3%), Moniliformis moniliformis (11.2%), and Nippostrongylus brasiliensis (14.2%). In a logistic model, the single risk factor identified for both M. moniliformis and P. muricola was R. rattus, compared with R. norvegicus (OR = 8.369 and 9.714, respectively). In comparison, the risk factor predicted for infection with N. brasiliensis was the northeastern section of Jamaica (OR = 11.000) compared with western Jamaica. Rictularia sp. represents a new geographic distribution record for the Caribbean region. Hymenolepis diminuta, M. moniliformis, Raillietina sp., and Rictularia sp. are potentially zoonotic, but only human infection with H. diminuta has been previously reported in the Caribbean.

Associations between two trematode parasites, an ectosymbiotic annelid, and Thiara (Tarebia) granifera (Gastropoda) in Jamaica.

This work describes associations of Thiara (Tarebia) granifera, its larval trematode community, and Chaetogaster limnaei limnaei at a freshwater reservoir in Jamaica. Larvae of 2 trematodes were present, i.e., a notocotylid (15.3%) and Philophthalmus sp. (1.3%), in 3,575 T. granifera examined. The prevalence of both infections increased with snail shell length (H  =  56, P < 0.01, H  =  23.1, P < 0.01, respectively). Only 3.0% (n  =  595) of infected snails possessed reproductive stages, compared with 90.3% (n  =  2,980) of uninfected snails (χ(2)  =  2,059.8, df  =  1, P < 0.001); both trematodes negatively impacted snail reproduction. Chaetogaster l. limnaei occurred within the mantle cavity of T. granifera with a prevalence of 2.3% (n  =  3,575); intensity ranged from 1 to 6 annelids. Notocotylid larvae occurred in 32.5% (n  =  83) of snails also harboring C. l. limnaei, compared with 14.9% (n  =  3,492) of snails lacking the annelid (χ(2)  =  18.127; P < 0.001). Chaetogaster l. limnaei appears not to influence the recruitment of egg-transmitted, notocotylid infections to snails. Ingestion of emergent cercariae by the annelid was observed; this may impact transmission of the parasite. The article presents the first report of a notocotylid and C. l. limnaei in T. granifera, and of Philophthalmus sp. in Jamaica.

Enzootic Angiostrongylus cantonensis in rats and snails after an outbreak of human eosinophilic meningitis, Jamaica.

After an outbreak in 2000 of eosinophilic meningitis in tourists to Jamaica, we looked for Angiostrongylus cantonensis in rats and snails on the island. Overall, 22% (24/109) of rats harbored adult worms, and 8% (4/48) of snails harbored A. cantonensis larvae. This report is the first of enzootic A. cantonensis infection in Jamaica, providing evidence that this parasite is likely to cause human cases of eosinophilic meningitis.

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 Crytosporidium 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 subjects'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 opportunisitc hemoflagellates such as Leishmania spp. and Trypanosoma cruzi is relatively low (AU)

Endoreplication in the ovary, testis, and intestine of strongyloides sterocalis

During development of the free-living adults of the human parasitic nematode Strongyloides 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 Feulgenstained 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 (AU)

Protein-losing enteropathy and trichuriasis - abstract

The phenomenon of protein-losing enteropathy (PLE) is defined as the abnormal loss of serum proteins into the gastrointestinal tract resulting from a variety of gastrointestinal abnormalities. Infestation of the large bowel and terminal ileum by adult Trichuris trichiura results in inflammatory reactions surrounding the sites of attachment. This study establishes Trichuris dysentery syndrome as one of the clinical disorders characterized by PLE. The clearance by the gut alpha-1-antitrypsin (OAT), a serum protein that resists proteolysis by digestive enzymes, was assessed in (i) subjects infected by the parasitic nematode and presenting with the Trichuris dysentery syndrome, and (ii) subjects manifesting no gastrointestinal diseases nor having conditions or receiving drugs likely to cause PLE. All subjects were within the age range 3 through 11 years, inclusive. A linear regression analysis showed a significant correlation between clearance of O AT and adult worm count (r = 0.4, p<0.05). The daily loss of this amount of serum protein is likely to be a considerable part of the cost to the host of this chronic parasitic infection (AU)

A survey of intestinal helminths of well-cared-for dogs in Jamaica, and their potential public health significance

This study investigates the level of helminthic infestation in better-cared-for dogs in a middle-class community in suburban Kingston. A canine zoographic study was conducted, and fresh faecal deposits were collected and analysed for helminth life-cycle stages. The survey indicated that 73 percent (n=93) of households in the study area owned one dog or more (mean=1.4). Resident's attitudes towards canine management suggested that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. Of 141 faecal specimens, 58 percent contained eggs or larvae of one or more of eight helminths: Uncinaria stenocephala (26 percent), Ancylostoma sp. (23 percent), Trichuris vulpis (9 percent), Toxocara canis (8 percent), Spirocerca lupi (6 percent), Strongyloides sp. (6 percent), Apophallus sp. (4 percent) and taeniids (1 percent). There was a high level of multiple infection in the host animals, with approximately one fifth of the infected samples containing three or more helminth types. Infection intensity was apparently low, but some dogs harboured heavy worm loads. (AU)

The human public health significance of well-cared for dogs in Jamaica - abstract

It is axiomatic that straying and neglected domestic fissipeds represent a health risk to the human population in tropical zones through transmission of parasitic infection. The object of this study was to investigate the level of helminthic infection in better-cared-for dogs in a middle-class suburban community in Jamaica and to analyse the data in the context of human health risk. The study area was located adjacent to the Mona Campus of the UWI. A canine demographic survey was conducted, and fresh faecal deposits collected and analysed, using the modified Ritchie formol-ether technique. Replication of faecal samples was minimised as far as possible. Seventy-three per cent (n=93) of the households owned one or more dogs (av. = 1.2; range = 1-4); there were 82 dogs resident in the study area. The attitude of residents towards canine management suggests that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. The following represents the prevalence and intensity of canine helminthic infection as determined by coproscopic analyses of 141 specimens; the prevalence was 26 percent and mean intensity (epg/1pg) 19 for the parasite, uncinaria stenocephala; prevalence was 23 percent and mean intensity (epg/1pg) 16 for the parasite, ancylostoma spp.; prevalence was 9 percent and mean intensity (epg/1pg) 4 for the parasite, trichuris vulpis; prevalence was 8 percent and mean intensity (epg/1pg) 9 for the parasite, toxocara canis; prevalence was 6 percent and mean intensity (epg/1pg) 10 for the parasite, strongyloides stercoralis; prevalence was 6 percent and mean intensity 15 for the parasite, spirocerca lupi; prevalence was 4 percent and mean intensity 13 for the parasite, apophallus sp.; prevalence was 1 percent and mean intensity 1 for the parasite, taeniid eggs. Apart from Apophallus sp. and, possibly, the Taeniid organisms,all these parasites infect humans. The comparatively high prevalence and intensity, and the multiple infections in dogs which are otherwise well-cared for, indicates the need for comprehensive canine and environmental monitoring in order to control pollution by eggs and larvae of helminth parasites with the indiscriminate defaecation by dogs in peri-domestic areas (AU)

Refeeding the malnourished child: effect on the fecundity of trichuris trichiura and ascaris lumbricoides - abstract

Ten children with either Trichuris trichiura and/or Ascaris lumbricoides infection were admitted to the nutrition rehabilitation ward at the Tropical Metabolism Research Unit, U.W.I. Treatment with anthelminthic was delayed until the children attained their normal weight-for-height. Total daily stool output and changes in faecal egg density were monitored for each child, the latter by Kato analyses of sub-samples taken from all daily stools, from admission through to anthelminthic treatment. Worm burdens were then assessed by the collection of expulsions. The fecundity of the whipworm appeared not to be affected by dietary rehabilitation. However, roundworm fecundity decreased, in some instances to zero. In some cases, the roundworms were expelled during the course of refeeding. Refeeding was seen to have an antagonistic effect on the fecundity of A. lumbricoides. The fact that whipworm fecundity went unaltered may be an indication of modulation of the host immune response (AU)

Strongyloides stercoralis: characterization of immunodiagnostic larval antigens

Forty-one-, 31-, and 28-kDa proteins of strongyloides stercoralis filariform larvae have previously been demonstrated to be sensitively and specifically recognized by serum IgG in individuals with strongyloidiasis. Characteristics of these proteins, their immunodominant epitopes, and reactive antibodies are described here. The proteins are soluble is aqueous as well as detergent extracts. The immunodominant epitopes are present in S. stercoralis but not in S. cebus or S. ratti. Epitopes on the three proteins are not shared, as determined by cross-absorption of serum with each of the size components on nitrocellulose. In most sera from strongyloidiasis patients there was reactivity to each of the proteins by IgG1 and IgG4, but reactivity by IgG2 or IgG3 was detectable only in a minority. A rabbit antiserum raised to a 41-kDa size fraction of S. stercoralis larvae reacted against a doublet of 41-kDa which was distinct from the immunodiagnostic 41-kDa protein.(AU)

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 strongyloides (AU)

Treatment of patients infected with Strongyloides stercoralis using ivermectin: assessment of efficacy and safety - abstract

Infections with Strongyloides stercoralis are often refractory to thiabendazole therapy in certain patients. Ivermectin is being used increasingly for treatment of uncomplicated infections; however, possible immunopathological changes associated with drug-induced release of antigens as observed with use of the drug in filariasis has not been studied in strongyloidiasis. In this study we used the enzyme linked immunosorbant assay (ELISA) technique to examine the profiles of S. stercoralis-specific IgG4, IgE and IgA against saline soluble filariform extracts in 8 patients treated for the parasite. All patients were found to be negative for the parasite by stool examination following treatment. Isotype levels fell in concert following treatment although there was considerable heterogeneity among patients. Levels remained low following treatment response but were still measurable for up to eighteen months post-treatment. There appeared to be no rapid release of parasite antigens following treatment. One patient exhibited a transient increase in levels of IgA after which there was a decline in this and all other isotypes. The single patient with proven chronic infection and a history of gastrointestinal symptoms exhibited almost ablated IgG1, IgE and IgA responses prior to treatment but had a significant IgG4 response which remained high following treatment. The reduction in antibody levels post-treatment may be used as confirmation of parasitological cure. The study showed that there was no rapid release of S. stercoralis antigens as seen in filarial infections and that Ivermectin is safe and effective against the parasite (AU)

Trichuriasis: the clinical picture - abstract

Human trichuriasis is a disease of clinical importance. This study reaffirms its status as such, highlighting the spectrum of manifestations presenting in individuals with Trichuris dysentery syndrome. Individuals with and without the syndrome, having in common a history of bloody, mucoid diarrhoea, were compared. Thirty-one patients (age range 2-10 years) were admitted to the Tropical Metabolism Research Unit. Anthropometry was preceded by full history and physical examination. The cause of dysenteric symptoms in each case was determined by stool analyses and colonscopy. Twenty-six of the patients had colitis secondary to massive Trichuris trichuriura infection. Worm burden was assessed by antihelminthic expulsion following colonoscopy. We present data (Table) from which an index of the diagnostic likelihood of Trichuris dysentery syndrome can be derived. When one or more of the symptoms are present in a child with over 3 months' history of diarrhoea, a diagnosis of the disease, confirmable by stool examination, and suitable antihelminthic treatment are indicated (AU)

Serum isotype responses in patients infected with Strongyloides stercoralis following treatment with ivermectin - abstract

Infections with Strongyloides stercoralis occur worldwide and can cause significant morbidity and mortality in man. They are often refractory to conventional chemotherapy especially in immunocompromised individuals. Recent studies have shown that Ivermectin is a safe and effective drug for use in uncomplicated infections. In this study, the profiles of parasite-specific IgG1, IgG4, IgE and IgA against a PBS soluble S. stercoralis filariform extract following treatment with ivermectin were investigated using the enzyme-linked immunosorbant assay (ELISA) technique. A series of 8 patients with parasitologically proven strongyloidiasis were treated with ivermectin and followed up for periods of 5 to 18 months. The predominant isotype found in the sera of patients from this series was IgG. High levels of IgG1 were recorded in young individuals while IgG4 was predominant in older persons. Levels of all isotypes declined following treatment and remained low up to eighteen months. Furthermore, no parasitological evidence of S. stercoralis infection was found after treatment, using agar plate and formalin-ether concentration methods. The reduction in antibody levels of post-treatment may be used as an indicator of adequate treatment and also demonstrate that patients are not exposed to drug-induced antigens following treatment. The study of S. stercoralis specific isotype profile will be useful in immuno-epidemiological studies in communities (AU)

Inactivation of strongyloides stercoralis filariform larvae in vitro by six Jamaican plant extracts and three commercial antihelminthics

In vitro bioassay of (a) aqueous methanol extracts (AME) of the green leaves of mimosa (Mimosa pudica), love weed (Cuscuta americana), vervine (Stachytarpheta jamaicensis), chicken weed (Salvia serotina) and breadfruit (Artocarpus altilis); (b) methanol-water fraction (MWF) of breadfruit leaves, and (c) commercially available drugs albendazole, thiabendazole and levamisole were assayed for nematode inactivating potential, using filariform larvae of Strongyloides stercoralis. Test larvae were obtained from a 10-day-old charcoal coproculture. Bioassays were conducted in Locke's solution, using 100 larvae in each of three replicates. Inactivation was recorded microscopically at 1, 2, 6 and 12 hours, then every 24 hours up to 5 days' incubation. It(50) (time for inactivation of 50 percent of larvae) values read: levamisole and mimosa extract < 1 hour; love weed extract, approximately 2 hours; breadfruit (MWF), 9.5 hours; chicken weed, 20 hours; albendazole, 35 hours; breadfruit (AME), 49 hours; thiabendazole, 74 hours and vervine extract, 81.5 hours. It(95) values followed a similar trend, and were approximately double the It(50) measures. A potential role for locally available natural products in the treatment of strongyloidiasis is highlighted (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)_

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)

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 percent and 85 percent following preincubation. Similarly, there was an increase in specifity from 94 percent to 97 percent. The IgG recognition of 41-, 31-, and 28-kD filariform larval components showed sensitivities of 100 percent, 85 percent and 65 percent, 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.(AU)