Parasitological Confirmation and Analysis of Leishmania Diversity in Asymptomatic and Subclinical Infection following Resolution of Cutaneous Leishmaniasis
| Autor: | Nancy G. Saravia, Luisa Rubiano, Alexandra Cossio, Maria Adelaida Gomez, Emily R. Adams, Mariana Rosales-Chilama, Rafael Góngora, Jimena Jojoa, Neal Alexander, Liliana Valderrama |
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| Rok vydání: | 2015 |
| Předmět: |
Male
Helminth genetics Polymerase Chain Reaction RNA Small Cytoplasmic Cluster Analysis Child Asymptomatic Infections Phylogeny Subclinical infection Aged 80 and over Leishmania education.field_of_study biology Transmission (medicine) lcsh:Public aspects of medicine DNA Kinetoplast DNA Helminth Middle Aged 3. Good health Blotting Southern Infectious Diseases Female medicine.symptom Research Article Adult lcsh:Arctic medicine. Tropical medicine Adolescent Genotype lcsh:RC955-962 Population Molecular Sequence Data Leishmaniasis Cutaneous Colombia Asymptomatic Young Adult Cutaneous leishmaniasis parasitic diseases medicine Humans education Aged Public Health Environmental and Occupational Health Genetic Variation lcsh:RA1-1270 Leishmaniasis Sequence Analysis DNA medicine.disease biology.organism_classification Virology Immunology Signal Recognition Particle |
| Zdroj: | PLoS Neglected Tropical Diseases PLoS Neglected Tropical Diseases, Vol 9, Iss 12, p e0004273 (2015) |
| ISSN: | 1935-2735 |
| Popis: | Background The contribution of individuals with subclinical infection to the transmission and endemicity of cutaneous leishmaniasis (CL) is unknown. Immunological evidence of exposure to Leishmania in residents of endemic areas has been the basis for defining the human population with asymptomatic infection. However, parasitological confirmation of subclinical infection is lacking. Methods We investigated the presence and viability of Leishmania in blood and non-invasive mucosal tissue samples from individuals with immunological evidence of subclinical infection in endemic areas for CL caused by Leishmania (Viannia) in Colombia. Detection of Leishmania kDNA was conducted by PCR-Southern Blot, and parasite viability was confirmed by amplification of parasite 7SLRNA gene transcripts. A molecular tool for genetic diversity analysis of parasite populations causing persistent subclinical infection based on PCR amplification and sequence analysis of an 82bp region between kDNA conserved blocks 1 and 2 was developed. Principal Findings Persistent Leishmania infection was demonstrated in 40% (46 of 114) of leishmanin skin test (LST) positive individuals without active disease; parasite viability was established in 59% of these (27 of 46; 24% of total). Parasite burden quantified from circulating blood monocytes, nasal, conjunctival or tonsil mucosal swab samples was comparable, and ranged between 0.2 to 22 parasites per reaction. kDNA sequences were obtained from samples from 2 individuals with asymptomatic infection and from 26 with history of CL, allowing genetic distance analysis that revealed diversity among sequences and clustering within the L. (Viannia) subgenus. Conclusions Our results provide parasitological confirmation of persistent infection among residents of endemic areas of L. (Viannia) transmission who have experienced asymptomatic infection or recovered from CL, revealing a reservoir of infection that potentially contributes to the endemicity and transmission of disease. kDNA genotyping establishes proof-of-principle of the feasibility of genetic diversity analysis in previously inaccessible and unexplored parasite populations in subclinically infected individuals. Author Summary A variable and often high proportion of individuals residing in areas where cutaneous leishmaniasis is endemic are exposed to Leishmania parasites, yet do not develop symptoms of disease. The role of this asymptomatic population in the transmission of disease is unknown and could interfere with the effectiveness of community or population-based control measures. Exposure to Leishmania is indirectly assessed by immunological tests; however, immunological evidence does not discriminate between historical exposure to the parasite and actual presence of parasites without causing clinical manifestations. We sought to determine whether viable Leishmania are present in individuals with immunological evidence of asymptomatic infection. Our results showed that at least 24% of individuals having immunological evidence of subclinical or asymptomatic infection harboured live Leishmania. These individuals may be at risk of activation of disease, or could represent an unperceived reservoir of parasites for vector-borne transmission. Characterization of Leishmania causing asymptomatic infection has not been possible due to technical limits of detection of parasites in low grade infections. We developed a molecular method that allows genotypic analysis of parasites involved in subclinical infection and potentially provides a means to assess their involvement in transmission. |
| Databáze: | OpenAIRE |
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