How is tick infection determined? - briefly
Tick-borne infection is identified by testing the tick or patient specimens with molecular methods (e.g., PCR), serological assays for specific antibodies, or microscopic examination for the pathogen.
How is tick infection determined? - in detail
Laboratory analysis of ticks begins with proper collection and preservation. Specimens are stored in 70 % ethanol or frozen at –20 °C to maintain nucleic acids and proteins. Identification of the tick species and life stage follows, using morphological keys or molecular barcoding, because infection prevalence varies among taxa.
The detection process proceeds through several established techniques:
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Polymerase chain reaction (PCR). Conventional, quantitative (qPCR), or multiplex PCR amplifies pathogen‑specific DNA or RNA. Primers target conserved regions of bacteria (e.g., 16S rRNA for Borrelia), protozoa (e.g., 18S rRNA for Babesia), or viruses (e.g., NS5 for tick‑borne encephalitis virus). qPCR provides cycle‑threshold values that correlate with pathogen load.
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Reverse transcription PCR (RT‑PCR). For RNA viruses, the assay first converts viral RNA to complementary DNA, then amplifies it. This method distinguishes active infection from residual nucleic acid.
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Sequencing. Sanger or next‑generation sequencing confirms PCR products, identifies strain variation, and detects co‑infections. Metagenomic approaches can uncover unexpected pathogens without prior primer design.
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Serological tests. Enzyme‑linked immunosorbent assays (ELISA) and immunofluorescence assays detect pathogen antigens or antibodies in tick homogenates. These are useful for large‑scale screening when molecular facilities are limited.
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Culture. Isolation of viable bacteria or protozoa on selective media validates infectivity but requires biosafety containment and extended incubation periods. Cultivation is rarely performed for viruses.
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Microscopy. Giemsa or fluorescent staining visualizes intracellular organisms directly in tick tissues. This technique offers rapid, qualitative assessment but lacks sensitivity for low‑level infections.
Quality control measures include the use of positive and negative controls in each assay, replication of samples, and verification of extraction efficiency with housekeeping gene amplification. Data are expressed as prevalence (percentage of infected ticks) or infection intensity (pathogen copies per tick). Statistical analysis compares infection rates across geographic regions, host habitats, and tick developmental stages.
Combining molecular, serological, and culture methods yields the most comprehensive picture of tick‑borne pathogen presence, supporting surveillance, risk assessment, and public‑health interventions.