Distinguishing body lice from head lice by multiplex real-time PCR analysis of the Phum_PHUM540560 gene.

Rezak Drali,Didier Raoult,Philippe Brouqui,Amina Boutellis,Jean Marc Rolain

doi:10.1371/journal.pone.0058088

Abstract

BackgroundBody louse or head louse? Once removed from their environment, body and head lice are indistinguishable. Neither the morphological criteria used since the mid-18th century nor the various genetic studies conducted since the advent of molecular biology tools have allowed body lice and head lice to be differentiated. In this work, using a portion of the Phum_PHUM540560 gene from the body louse, we aimed to develop a multiplex real-time polymerase chain reaction (PCR) assay to differentiate between body and head lice in a single reaction.Materials and MethodsA total of 142 human lice were collected from mono-infested hosts from 13 countries on five continents. We first identified the louse clade using a cytochrome b (CYTB) PCR sequence alignment. We then aligned a fragment of the Phum_PHUM540560 gene amplified from head and body lice to design-specific TaqMan© FAM- and VIC-labeled probes.ResultsAll the analyzed lice were Clade A lice. A total of 22 polymorphisms between the body and head lice were characterized. The multiplex real-time PCR analysis enabled the body and head lice to be distinguished in two hours. This method is simple, with 100% specificity and sensitivity.ConclusionsWe confirmed that the Phum_PHUM540560 gene is a useful genetic marker for the study of lice.

Highlights

Body and head lice are hematophagous ectoparasites that are specific to humans [1] and have different ecologies
The multiplex real-time polymerase chain reaction (PCR) analysis enabled the body and head lice to be distinguished in two hours
In 1978, the use of microscopes to observe body and head lice collected from Ethiopians with double infestations allowed a researcher to conclude that the lice represented two distinct species, Pediculus humanus Linnaeus and Pediculus capitis De Geer

Summary

Introduction

Body and head lice are hematophagous ectoparasites that are specific to humans [1] and have different ecologies. Since the mid-18th century, morphological criteria such as size, shape and color gradation have been used to differentiate body and head lice into two distinct species [6]. In 1978, the use of microscopes to observe body and head lice collected from Ethiopians with double infestations allowed a researcher to conclude that the lice represented two distinct species, Pediculus humanus Linnaeus and Pediculus capitis De Geer. He based his assertion on the length of the tibia of the louse’s middle leg [7]. In this work, using a portion of the Phum_PHUM540560 gene from the body louse, we aimed to develop a multiplex real-time polymerase chain reaction (PCR) assay to differentiate between body and head lice in a single reaction

Objectives

Methods

Results

Conclusion