Djamel Tahir

Dr. Djamel Tahir

Institut Pasteur, Paris, Île-de-France, France
orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 June 2017 in Parasites & Vectors
Verified
Journal Article
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MDMustapha Dahmani
Mustapha Dahmani
BDBernard Davoust
Bernard Davoust
Djamel TahirDjamel Tahir
Djamel Tahir
Didier RaoultDidier Raoult
Didier Raoult
FFFlorence Fenollar
Florence Fenollar
OMOleg Mediannikov
Oleg Mediannikov
Corsica is a French island situated in the Mediterranean Sea. The island provides suitable natural conditions to study disease ecology, especially tick-borne diseases and emerging diseases in animals and ticks. The family Anaplasmataceae is a member of the order Rickettsiales; it includes the genera Anaplasma, Ehrlichia, Neorickettsia and Wolbachia. Anaplasmosis and ehrlichiosis traditionally refer to diseases caused by obligate intracellular bacteria of the genera Anaplasma and Ehrlichia. The aim of this study was to identify and estimate the prevalence of Anaplasmataceae species infecting domestic animals and ticks in Corsica. In this study, 458 blood samples from sheep, cattle, horses, goats, dogs, and 123 ticks removed from cattle, were collected in Corsica. Quantitative real-time PCR screening and genetic characterisation of Anaplasmataceae bacteria were based on the 23S rRNA, rpoB and groEl genes. Two tick species were collected in the present study: Rhipicephalus bursa (118) and Hyalomma marginatum marginatum (5). Molecular investigation showed that 32.1% (147/458) of blood samples were positive for Anaplasmataceae infection. Anaplasma ovis was identified in 42.3% (93/220) of sheep. Anaplasma marginale was amplified from 100% (12/12) of cattle and two R. bursa (2/123). Several potentially new species were also identified: Anaplasma cf. ovis, “Candidatus Anaplasma corsicanum”, “Candidatus Anaplasma mediterraneum” were amplified from 17.3% (38/220) of sheep, and Anaplasma sp. marginale-like was amplified from 80% (4/5) of goats. Finally, one R. bursa tick was found to harbour the DNA of E. canis. All samples from horses and dogs were negative for Anaplasmataceae infection. To our knowledge, this study is the first epidemiological survey on Anaplasmataceae species infecting animals and ticks in Corsica and contributes toward the identification of current Anaplasmataceae species circulating in Corsica.

1 October 2016 in Ticks and Tick-borne Diseases
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Journal Article
Closed access
Djamel TahirDjamel Tahir
Djamel Tahir
CSCristina Socolovschi
Cristina Socolovschi
JMJean-Lou Marié
Jean-Lou Marié
GGGautier Ganay
Gautier Ganay
JBJean Michel Berenger
Jean Michel Berenger
PPPhilippe Parola
Philippe Parola

16 June 2020 in Microorganisms
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Journal Article
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Djamel TahirDjamel Tahir
Djamel Tahir
LMLeon Meyer
Leon Meyer
JFJosephus Fourie
Josephus Fourie
FJFrans Jongejan
Frans Jongejan
TMThomas Mather
Thomas Mather
MVMarie Varloud
Marie Varloud
Ticks are obligate hematophagous arthropods and act as vectors for a great variety of pathogens, including viruses, bacteria, protozoa, and helminths. Some tick-borne viruses, such as Powassan virus and tick-borne encephalitis virus, are transmissible within 15–60 min after tick attachment. However, a minimum of 3–24 h of tick attachment is necessary to effectively transmit bacterial agents such as Ehrlichia spp., Anaplasma spp., and Rickettsia spp. to a new host. Longer transmission periods were reported for Borrelia spp. and protozoans such as Babesia spp., which require a minimum duration of 24–48 h of tick attachment for maturation and migration of the pathogen. Laboratory observations indicate that the probability of transmission of tick-borne pathogens increases with the duration an infected tick is allowed to remain attached to the host. However, the transmission time may be shortened when partially fed infected ticks detach from their initial host and reattach to a new host, on which they complete their engorgement. For example, early transmission of tick-borne pathogens (e.g., Rickettsia rickettsii, Borrelia burgdorferi, and Babesia canis) and a significantly shorter transmission time were demonstrated in laboratory experiments by interrupted blood feeding. The relevance of such situations under field conditions remains poorly documented. In this review, we explore parameters of, and causes leading to, spontaneous interrupted feeding in nature, as well as the effects of this behavior on the minimum time required for transmission of tick-borne pathogens.

26 October 2019 in Veterinary World
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Journal Article
Open access
Djamel TahirDjamel Tahir
Djamel Tahir
BDBernard Davoust
Bernard Davoust
Philippe ParolaPhilippe Parola
Philippe Parola
Vector-borne diseases (VBDs) are among the leading causes of morbidity and mortality in humans and animals. The scale of VBDs is increasing worldwide, including in the Mediterranean Basin, a region exposed to climate changes. Indeed, weather conditions may influence the abundance and distribution of vectors. The vector-borne nematode diseases of dogs and cats, such as dirofilariosis, onchocercosis, thelaziosis, Cercopithifilaria, and Acanthocheilonema infections, are some of these vectorized diseases, several of which are zoonoses. They are all caused by parasitic nematodes transmitted by arthropods, including mosquitoes (Dirofilaria spp.), black flies (Onchocerca lupi), drosophilids (Thelazia callipaeda), ticks (Acanthocheilonema dracunculoides and Cercopithifilaria bainae), and fleas and lice (Acanthocheilonema reconditum). The control and prevention of these infections and diseases require a multidisciplinary approach based on strengthening collaboration between the different actors in the fields of health, research, sociology, economics, governments and citizens, to improve human, animal, and ecosystem health. This is the concept of "one health." The review aimed to provide a general update on the spatial and temporal distribution of vector-borne nematodes diseases affecting companion animals and humans, as well as the vectors involved in the Mediterranean area. Simultaneously, certain epidemiological parameters, diagnosis, treatment, and control of these diseases based on the "one health" concept will also be discussed.

20 December 2017 in PLOS Neglected Tropical Diseases
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Djamel TahirDjamel Tahir
Djamel Tahir
LALionel Almeras
Lionel Almeras
MVMarie Varloud
Marie Varloud
DRDidier Raoult
Didier Raoult
BDBernard Davoust
Bernard Davoust
Philippe ParolaPhilippe Parola
Philippe Parola
Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is an emerging tool for routine identification of bacteria, archaea and fungi. It has also been recently applied as an accurate approach for arthropod identification. Preliminary studies have shown that the MALDI-TOF MS was able to differentiate whether ticks and mosquitoes were infected or not with some bacteria and Plasmodium parasites, respectively. The aim of the present study was to test the efficiency of MALDI-TOF MS tool in distinguishing protein profiles between uninfected mosquitoes from specimens infected by filarioid helminths. Aedes aegypti mosquitoes were engorged on microfilaremic blood infected with Dirofilaria immitis, Brugia malayi or Brugia pahangi. Fifteen days post-infective blood feeding, a total of 534 mosquitoes were killed by freezing. To assess mass spectra (MS) profile changes following filariae infections, one compartment (legs, thorax, head or thorax and head) per mosquito was submitted for MALDI-TOF MS analysis; the remaining body parts were used to establish filariae infectious status by real-time qPCR. A database of reference MS, based on the mass profiles of at least two individual mosquitoes per compartment, was created. Subsequently, the remaining compartment spectra (N = 350) from Ae. aegypti infected or not infected by filariae were blind tested against the spectral database. In total, 37 discriminating peak masses ranging from 2062 to 14869 daltons were identified, of which 17, 11, 12 and 7 peak masses were for legs, thorax, thorax-head and head respectively. Two peak masses (4073 and 8847 Da) were specific to spectra from Ae. aegypti infected with filariae, regardless of nematode species or mosquito compartment. The thorax-head part provided better classification with a specificity of 94.1% and sensitivity of 86.6, 71.4 and 68.7% of D. immitis, B. malayi and B. pahangi respectively. This study presents the potential of MALDI-TOF MS as a reliable tool for differentiating non-infected and filariae-infected Ae. aegypti mosquitoes. Considering that the results might vary in other mosquito species, further studies are needed to consolidate the obtained preliminary results before applying this tool in entomological surveillance as a fast mass screening method of filariosis vectors in endemic areas. Filariosis is a disease group affecting humans and animals, caused by nematode parasites of the family Onchocercidae, superfamily Filarioidea. These parasites can be transmitted, essentially, by mosquitoes during blood meals of infected female specimens. Screening vectors for these filariae currently relies on time- and resource-consuming methods such as dissection and polymerase chain reaction-based methods. Here, we applied matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to assess whether this tool can detect changes in the protein profiles of Aedes aegypti infected with filarioid helminths compared to those uninfected by testing different parts of mosquitoes. First a reference mass spectra database from Ae. aegypti infected or not infected by filariae was created using MS from 47 specimen compartments. Then we tested the remaining mass spectra (350 x 4) in a blind validation test. Regardless of filariae species, the best correct classification rate was obtained from the thorax-head part with a specificity of 94.1% and sensitivity of 86.6, 71.4 and 68.7% for non-infected and D. immitis, B. malayi and B. pahangi infected mosquitoes respectively. The results indicated that MALDI-TOF MS is potentially able to screen Aedes aegypti mosquitoes as being non-infected or filariae-infected. Furthermore, complementary works using other mosquito species infected with different filarioids are needed to reinforce these preliminary results prior to apply this tool on field samples.

29 June 2018 in PLOS Neglected Tropical Diseases
Verified
Journal Article
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KBKahina Bennai
Kahina Bennai
Djamel TahirDjamel Tahir
Djamel Tahir
ILIsmail Lafri
Ismail Lafri
ABAmina Bendjaballah-Laliam
Amina Bendjaballah-Laliam
IBIdir Bitam
Idir Bitam
Philippe ParolaPhilippe Parola
Philippe Parola
Leishmania parasites are transmitted by female phlebotomine sand flies that maintain the enzootic cycle by circulating between sylvatic and domestic mammals. Humans are part of this cycle as accidental hosts due to the vector’s search for a source of blood. In Algeria, Human Leishmaniases (HL) are endemic and represent a serious public health problem because of their high annual incidence and their spread across the country. The aim of this study is to identify sand fly species fauna (vectors of Leishmania), determine their infection rate and identify their feeding preferences using molecular tools in a hypoendemic focus of HL located in the province of Tipaza, northern Algeria. An entomological survey using CDC light traps was conducted between July and October of 2015 in four HL affected peri-urban locations in the province of Tipaza, northern Algeria. Sand flies were identified using the morphological criteria of the genitalia for the males and spermathecae for the females. Leishmania DNA was detected in pooled female sand flies (N = 81 pools with 8–10 specimens per pool) using quantitative real-time polymerase chain reaction (qPCR) targeting two different genes: kDNA-PCR and 18S rRNA. To identify their blood meal sources, blood-fed female sand flies were analyzed by PCR-sequencing targeting the vertebrate cytochrome c oxidase I (COI) gene. A total of 4,045 sand flies were caught, of which 3,727 specimens were morphologically identified. Seven species were recorded: P. (L.) perniciosus (50.28%), P. (L.) perfiliewi (26.13%), P. (L.) longicuspis (21.92%), Sergentomyia (S.) minuta (0.85%), P. (P.) papatasi (0.42%), P. (L.) langeroni (0.32%) and P. (L.) ariasi (0.05%). Afterwards, 740 female specimens were randomly selected and divided into 81 pools and were then screened to investigate the presence of Leishmania spp. L. infantum DNA was detected in three pools, corresponding to three sand fly specimens (one each). The infection rate was 0.33% (2/600) for P. (L.) perniciosus and 2.56% (1/39) for P. (L.) perfiliewi. Analysis of the blood feeding sources (N = 88 specimens) revealed that sand flies belonging to Larroussius subgenera, mainly (71.5%) feed on small ruminants. Human blood is the second feeding source (17%), eight specimens (9%) were found to feed on equines and no domestic reservoir (dog) blood was found. The presence of human leishmaniasis cases, the high abundance of Phlebotomus (Larroussius) species which are proven or suspected vectors of L. infantum, and the detection of L. infantum DNA from its natural vectors (P. (L.) perniciosus, P. (L.) perfiliewi), in addition to the blood-feeding of positive females for L. infantum on humans blood, prove that the major elements of the epidemiological transmission cycle of L. infantum are present and indicate risk factors for an outbreak of the disease in the province of Tipaza. Leishmaniases are a group of diseases with various clinical manifestations caused by parasites (Leishmania spp.). More than 20 Leishmania species that affect human and mammals are transmitted by the bite of an infected female phlebotomine sand flies. In Algeria, two main forms of the disease exist: visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). Although CL is the most common form of the disease, VL is the most serious and can be fatal if untreated. The purpose of the study was to investigate sand fly species fauna, their infection rate and feeding preference determination in a hypoendemic focus of human leishmaniasis located in the province of Tipaza, northern Algeria using molecular techniques. Seven phlebotomine sand flies species were recorded in this study. In addition, natural infection by L. infantum was confirmed in two sand flies species (P. (L). perniciosus and P. (L). perfiliewi). Human blood was the second (17%) feeding source after ruminants (74.11%%).