A recent paper claims to have found a new Clade of head louse with potential to transmit diseases.
The study, by Drali et al., was published in the September 2015 edition of the American Journal of Tropical Medicine and Hygiene. It identifies a new mitochondrial Clade of pediculus, comprising both body and head lice.
This new Clade D (an addition to the existing three Clades, A-C), is described as a possible vector for transmission of Bartonella quintana and Yersinia pestis. It is commonly accepted that the human head louse is not a disease vector (unlike the body louse), but this new finding agrees with earlier evidence that disease transmission may be possible in certain circumstances.
This new head lice Clade has received independent support from a new study by Ashfaq et al., published in the September 2015 edition of Scientific Reports. This study analysed mitochondrial gene sequences from head lice and found two new Clades, D and E, in addition to the three standard Clade groupings.