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Human exposure to Anaplasma phagocytophilum in Portugal

A S Santos1, F Bacellar, J S Dumler

  • 1Centro de Estudos de Vectores e Doenças Infecciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Avenida da Liberdade 5, 2965-575 Aguas de Moura, Portugal. ana.santos@insa.min-saude.pt

Annals of the New York Academy of Sciences
|November 23, 2006
PubMed

Insights

This study found evidence of human exposure to Anaplasma phagocytophilum in Portugal. Patients with Lyme borreliosis (LB) were significantly more likely to have antibodies, suggesting a link between these tick-borne infections.

Area of Science:

  • Medical Microbiology
  • Infectious Diseases
  • Epidemiology

Background:

  • Anaplasma phagocytophilum is an emerging tick-borne bacterium causing human granulocytic anaplasmosis.
  • Lyme borreliosis (LB) and boutonneuse fever (BF) are other tick-borne diseases prevalent in Portugal.
  • Co-infection or cross-reactivity between tick-borne pathogens is a diagnostic challenge.

Purpose of the Study:

  • To investigate the seroprevalence of Anaplasma phagocytophilum in patients with suspected tick-borne diseases in Portugal.
  • To determine if there is an association between Anaplasma phagocytophilum exposure and Lyme borreliosis.

Main Methods:

  • Retrospective analysis of serum samples from 367 patients in Portugal.
  • Detection of Anaplasma phagocytophilum antibodies using indirect immunofluorescence (IFA) and Western blot (WB) assays.
  • Comparison of seropositivity rates between patients with confirmed LB, suspected LB, LB/BF, and healthy controls.

Main Results:

  • Overall seropositivity for Anaplasma phagocytophilum was 7.8% in patients with LB and suspected LB.
  • A significantly higher seropositivity rate was observed in LB and suspected LB groups compared to seronegative and healthy controls (P < 0.001).
  • Only one case (0.4%) in the LB/BF seronegative group showed confirmed disease.

Conclusions:

  • This study provides the first evidence of human exposure to Anaplasma phagocytophilum in Portugal.
  • Patients with Lyme borreliosis are significantly more likely to have been exposed to Anaplasma phagocytophilum or a similar bacterium.
  • Further research is warranted to understand the clinical significance and epidemiology of Anaplasma phagocytophilum in Portugal.

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