John F Lindo

Immunodiagnosis of Strongyloides stercoralis infection: a method for increasing the specificity of the indirect Elisa

Indirect enzyme-linked immunosorbent assay (ELISA) allows sensitive detection of serum immunoglobulin (Ig) G against a soluble extract of Strongyloides stercoralis infective larvae. In this study, 40/40 (100%) human strongyloidiasis sera had high levels of anti-S. stercoralis IgG, but 30/40 (75%) filariasis sera, and 12/40 (30%) necatoriasis sera also had higher levels than control sera from UK residents. In attempts to increase the assay specificity by absorption of cross-reactive IgG, the effectiveness of pre-incubation of sera with extracts of different parasitic nematodes was investigated. One hour of incubation with 20 micrograms/ml aqueous extract of Onchocerca gutturosa absorbed cross-reactive IgG in most filariasis and necatoriasis sera, reducing the proportion with IgG levels above the positivity threshold by more than one-half. Preliminary results suggest that absorption with extracts of other filarial nematodes is equally effective, and that some of the cross-reactive IgG is directed against phosphorylcholine. Cross-reactive IgG in most necatoriasis sera was effectively absorbed with 20 micrograms/ml extract of Necator americanus. Cross-reactive IgG was not effectively absorbed with an extract of Ascaris lumbricoides. Absorption of cross-reactive IgG is an effective means of increasing the specificity of the indirect ELISA, for use in the immunodiagnosis and immuno-epidemiology of S. stercoralis infection.

Unique Cryptosporidium Population in HIV-Infected Persons, Jamaica

A cryptosporidiosis survey showed the presence of Cryptosporidium hominis, C. parvum, C. canis, and C. felis in 25, 7, 1, and 1 HIV-positive persons from Jamaica, respectively; 1 person had both C. hominis and C. felis. Multilocus sequence typing indicated the presence of a homogeneous but geographically distinct C. hominis population in Jamaica.

Pathogenic Acanthamoeba strains from water sources in Jamaica, West Indies

Abstract In 2004, samples of tap water and of river and sea water associated with human activities were collected in Jamaica, West Indies, and checked for free-living Acanthamoeba. The morphologies of the cysts and trophozoites observed and the results of PCR-based amplifications with a genus-specific primer pair were used to identify the Acanthamoeba isolates. The potential of each isolate as a human pathogen was then evaluated using thermotolerance and osmotolerance assays and two PCR-based assays for Acanthamoeba pathogenesis. Acanthamoeba were identified in 36.1%, 26.4% and 49.6% of the tap-, river- and sea-water samples collected, respectively. Pathogenic potential was shown by 60.0% of the Acanthamoeba strains isolated from tap water, 68.4% of the strains from river water, and 40.4% of the seawater strains. Sequencing of ribosomal DNA revealed the T1, T2, T4, T5, T7, T9 and T11 genotypes. Isolates of the T4 genotype were collected from tap, rain and sea water and, as expected, exhibited the most pathogenic traits; most were osmotolerant, thermotolerant and expressing extracellular serine protease. This is the first study of the occurrence and distribution of Acanthamoeba in water in the West Indies, and the results confirm the presence of potentially pathogenic strains in Jamaica.

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.

Isolation and characterization of Acanthamoeba strains from soil samples in Gran Canaria, Canary Islands, Spain.

Free-living Amoebae of Acanthamoeba genus include non-pathogenic and pathogenic strains that are currently classified in 18 different genotypes, T1–T18. In this study, a survey was carried out to evaluate the presence of Acanthamoeba strains in soil samples collected between 2012 and 2013 in Gran Canaria Island, Canary Islands, Spain. Samples were inoculated onto non-nutrient agar (NNA) plates and were checked for the presence of Acanthamoeba. Identification of Acanthamoeba strains was based on the morphology of the cyst and trophozoite forms. Subsequently, positive samples were cloned for their molecular characterization at the genotype level by sequencing the DF3 region located in the 18S rDNA gene of Acanthamoeba as previously described. Sequencing results revealed the presence of T2, T5 and T4 genotypes within the studied samples. To the best of our knowledge, this is the first report demonstrating the presence of Acanthamoeba in Gran Canaria Island and the first study at the genotype level in the Canary Islands.

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.

Towards effective control of Strongyloides stercoralis

Abstract A widespread intestinal parasite of humans, Strongyloides stercoralis has long been considered very difficult to control in endemic communities. This situation is now changing. In this article, David Conway, John Lindo, Ralph Robinson and Don Bundy review recent advances in diagnosis, chemotherapy and epidemiology of S. stercoralis infection, and highlight new options for control.

Plasmodium malariae in Haitian Refugees, Jamaica

Since 1963, reported malaria transmission in Haiti has been restricted to Plasmodium falciparum. However, screening of Haitian refugees in Jamaica in 2004, by microscopic examination, identified P. falciparum, P. vivax, and P. malariae. PCR confirmed the P. malariae and P. falciparum but not P. vivax infections. DNA sequencing and rRNA gene sequences showed transmission of P. malariae. This report confirms that P. malariae is still being transmitted in Haiti.

Eliminating Lymphatic Filariasis, Onchocerciasis, and Schistosomiasis from the Americas: Breaking a Historical Legacy of Slavery

velopment in the United States and in the Caribbean led to the spontaneous disappearance of LF in some areas and substantial declines in the prevalence of infection in others [7]. Ongoing transmission in the Western Hemisphere, now limited to four countries (Brazil, the Dominican Republic, Haiti, and Guyana), is concentrated in impoverished settings and appears to be a growing problem in urban slums. LF elimination programs based on the mass distribution of antifilarial drugs have been developed in all four countries and have resulted in declines in the prevalence of filarial infection ([8] and unpublished data). However, all four programs are resource challenged and none have achieved full coverage of at-risk populations.

Human Angiostrongylus cantonensis, Jamaica

To the Editor: Angiostrongylus cantonensis is the most common cause of eosinophilic meningoencephalitis worldwide (1). The parasites presence has been well documented in Jamaica in rats (definitive host) and a variety of mollusks (intermediate hosts); infections occur in humans sporadically on the island. However, the mode of transmission of infections to humans in Jamaica, where raw or undercooked mollusks are not usually eaten, is not well understood (2).