Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a devastating invasive pest of tomato crops in several areas around the world including Africa. Here, we comprehensively review and discuss the relevant scientific knowledge on its occurrence, biological and ecological aspects, fortuitous insect natural enemies, and potential advantages and constraints of pest management scenarios adopted against this pest in tomato crops in both Northern and Sub-Saharan Africa. We conclude the manuscript with a comprehensive research agenda providing future priorities towards sustainable control of this important tomato pest.

Occurrence, biology, natural enemies and management of Tuta absoluta in Africa

Rickettsia felis is an emerging insect-borne rickettsial pathogen and the causative agent of flea-borne spotted fever. First described as a human pathogen from the USA in 1991, R. felis is now identified throughout the world and considered a common cause of fever in Africa. The cosmopolitan distribution of this pathogen is credited to the equally widespread occurrence of cat fleas (Ctenocephalides felis), the primary vector and reservoir of R. felis. Although R. felis is a relatively new member of the pathogenic Rickettsia, limited knowledge of basic R. felis biology continues to hinder research progression of this unique bacterium. This is a comprehensive review examining what is known and unknown relative to R. felis transmission biology, epidemiology of the disease, and genetics, with an insight into areas of needed investigation.

https://link.springer.com/content/pdf/10.1007%2Fs40475-016-0070-6.pdf

Rickettsia felis, an Emerging Flea-Borne Rickettsiosis

Ticks, as obligate blood-sucking ectoparasites, attack a broad range of vertebrates and transmit a great diversity of pathogenic microorganisms They are considered second only to mosquitoes as vectors of human disease, and the most important vector of pathogens of domestic and wild animals Of the 117 described species in the Chinese tick fauna, 60 are known to transmit one or more diseases: 36 species isolated within China and 24 species isolated outside China Moreover, 38 of these species carry multiple pathogens, indicating the potentially vast role of these vectors in transmitting pathogens Spotted fever is the most common tick-borne disease, and is carried by at least 27 tick species, with Lyme disease and human granulocytic anaplasmosis ranked as the second and third most widespread tick-borne diseases, carried by 13 and 10 species, respectively Such knowledge provides us with clues for the identification of tick-associated pathogens and suggests ideas for the control of tick-borne diseases in China However, the numbers of tick-associated pathogens and tick-borne diseases in China are probably underestimated because of the complex distribution and great diversity of tick species in this country

/pdf/tick-borne-pathogens-and-the-vector-potential-of-ticks-in-q2oico2w4t.pdf

Tick-borne pathogens and the vector potential of ticks in China.

The flea-borne rickettsioses murine typhus (Rickettsia typhi) and flea-borne spotted fever (FBSF) (Rickettsia felis) are febrile diseases distributed among humans worldwide. Murine typhus has been known to be endemic to Kenya since the 1950s, but FBSF was only recently documented in northeastern (2010) and western (2012) Kenya. To characterize the potential exposure of humans in Kenya to flea-borne rickettsioses, a total of 330 fleas (134 pools) including 5 species (Xenopsylla cheopis, Ctenocephalides felis, Ctenocephalides canis, Pulex irritans, and Echidnophaga gallinacea) were collected from domestic and peridomestic animals and from human dwellings within Asembo, western Kenya. DNA was extracted from the 134 pooled flea samples and 89 (66.4%) pools tested positively for rickettsial DNA by 2 genus-specific quantitative real-time PCR (qPCR) assays based upon the citrate synthase (gltA) and 17-kD antigen genes and the Rfelis qPCR assay. Sequences from the 17-kD antigen gene, the outer membrane protein (omp)B, and 2 R. felis plasmid genes (pRF and pRFd) of 12 selected rickettsia-positive samples revealed a unique Rickettsia sp. (n=11) and R. felis (n=1). Depiction of the new rickettsia by multilocus sequence typing (MLST) targeting the 16S rRNA (rrs), 17-kD antigen gene, gltA, ompA, ompB, and surface cell antigen 4 (sca4), shows that it is most closely related to R. felis but genetically dissimilar enough to be considered a separate species provisionally named Candidatus Rickettsia asemboensis. Subsequently, 81 of the 134 (60.4%) flea pools tested positively for Candidatus Rickettsia asemboensis by a newly developed agent-specific qPCR assay, Rasemb. R. felis was identified in 9 of the 134 (6.7%) flea pools, and R. typhi the causative agent of murine typhus was not detected in any of 78 rickettsia-positive pools assessed using a species-specific qPCR assay, Rtyph. Two pools were found to contain both R. felis and Candidatus Rickettsia asemboensis DNA and 1 pool contained an agent, which is potentially new.

/pdf/molecular-detection-of-rickettsia-felis-and-candidatus-53azudcr4n.pdf

Molecular detection of Rickettsia felis and Candidatus Rickettsia Asemboensis in Fleas from Human Habitats, Asembo, Kenya

Hedgehogs have become a popular pet despite their potential role in zoonotic disease transmission. We conducted an entomological study in a mountainous region of northeast Algeria in which we collected 387 fleas (Archeopsylla erinacei) and 342 ticks (Rhipicephalus sanguineus and Haemaphysalis erinacei) from Paraechinus aethiopicus and Atelerix algirus hedgehogs. Of the hedgehogs sampled, 77.7% and 91% were infested with fleas and ticks, respectively. Significantly more ticks and fleas were collected from A. algirus than from P. aethiopicus. Rickettsia felis was detected in 95.5% of fleas and R. massiliae was detected in 6.25% of Rh. sanguineus ticks by molecular tools. A new Rickettsia species of the spotted fever group was detected in 11.25% of Rh. sanguineus and in 77% of H. erinacei ticks. Overall, we show that hedgehogs can act as hosts for ectoparasites infected with several rickettsial agents. These data justify a more detailed investigation of animal reservoirs for Rickettsiae.

Rickettsiae in arthropods collected from the North African Hedgehog (Atelerix algirus) and the desert hedgehog (Paraechinus aethiopicus) in Algeria.

The effect of salinity and water stresses on the essential oil components of Rosmarinus officinalis essential oil was investigated. Rosemary plants were submitted to different water treatments: tap water (TW), salt water (SW) and without irrigation (NIR). GC/MS analysis showed that ten and eleven volatile compounds were identified in essential oil of rosemary plants irrigated with tap water (TW) and salt water (SW), respectively. However, thirteen volatile compounds were identified in essential oil of non-irrigated plants (NIR). Moreover, among these compounds, α-Pinene, Eucalyptol (1,8 Cineol), Camphene, Borneol, D-verbenone, Bornyl acetate were the major components of oil. Also, GC/MS results highlighted that non-irrigated rosemary plants showed the highest essential oil yield (Y). Obtained oil yields followed the order YNIR > YTW > YSW. In conclusion, qualitative and quantitative differences in rosemary essential oil components were highlighted in relation to water stress.

https://www.mdpi.com/2073-4395/9/5/214/pdf

Effect of Salinity and Water Stress on the Essential Oil Components of Rosemary (Rosmarinus officinalis L.)

The study of endoparasites (helminths and coccidians) in the Algerian (Atelerix algirus) and desert (Paraechinus aethiopicus) hedgehogs was performed between July 2008 and October 2009. The helminth species found included two cestodes, Mathevotaenia erinacei (Anoplocephalidae) and an unidentified cestode larva in the mesentery, eight species of nematodes: Aonchotheca erinacei (Trichuridae) in the intestine, spirurids (Spiruridae) in the intestine, Crenosoma striatum (Crenosomatidae) in the lungs, Gongylonema mucronatum (Gongylonematidae) in the oesophagus, Physaloptera clausa (Physalopteridae) in the stomach, Physaloptera sp. larvae (Physalopteridae) in the mesentery, Pterygodermatites plagiostoma (Rictulariidae) in the stomach, Spirura rytipleurites seurati (Spiruridae) in the intestine; and two acanthocephalans, Moniliformis moniliformis (Moniliformidae) in the intestine and larvae of an unknown acanthocephalan species in the mesentery. The general prevalence was high in both hosts, 92% in Atelerix algi...

Endoparasites (helminths and coccidians) in the hedgehogs Atelerix algirus and Paraechinus aethiopicus from Algeria

ResumeCe travail a pour objectif l’etude de quelques aspects bio-ecologiques de la cochenille violette, Parlatoria oleae Colvee 1880, bio-agresseur des cultures de l’Olivier en regions arides. Le suivi du cycle biologique ainsi que la demo-ecologie de ce ravageur ont ete realises grâce a des denombrements periodiques des populations sur les differents organes de l’arbre (methodes de Vasseur & Schvester) de decembre 2010 a decembre 2011 dans la region d’Ain Touta (nord-est algerien). L’espece y a montre deux generations par an : une generation printaniere se developpant entre avril et juillet et une generation automnale evoluant entre aout et octobre. La ponte debuta en avril et s’echelonna jusqu‘a la fin septembre. L’exposition nord est la plus favorable a cette diaspine qui y trouve des conditions microclimatiques optimales pour son developpement. La ponte moyenne est de 8 a 9 œufs par femelle. L’analyse statistique de l’effet des conditions climatiques etudiees (temperatures minimale, maximale et moyenn...

Effet du climat et de l’exposition sur la dynamique des populations de la cochenille violette, Parlatoria oleae Colvée (Hemiptera : Diaspididae), en conditions arides

The population structure, age and growth of Luciobarbus callensis (Cyprinidae) in a man-made lake in the Maghreb (NE Algeria).

Knowledge of the biological traits of native fishes distributed throughout the Maghreb, e.g., Luciobarbus callensis, the target species of this study, is essential for assessing the status of these species and for improving their conservation. In this study, the age and growth characteristics of a population in a man-made lake showing temporal variations in ecological conditions and managed for agricultural purposes were investigated. The sampled population showed a wide range of ages and an age structure dominated by middle-aged cohorts (4+ ? 7+). Compared with stream populations, the studied stock was characterised by a large number of age groups. The annual growth of middle-aged fish was not great and decreased with longevity. The growth pattern was seasonal, consisting of a single growth period extending from the end of winter to spring, immediately prior to the reproductive period. Relative abundance showed slight differences between seasons. The highest values of somatic condition occurred immediately following the reproductive period. Most likely, the characteristics of the species were affected by the ecological variation of the reservoir and by the highly variable stream flowing into the reservoir. However, Luciobarbus callensis showed a high adaptability to these artificial systems.

Mohamed Biche

Papers

Rickettsiae in arthropods collected from the North African Hedgehog (Atelerix algirus) and the desert hedgehog (Paraechinus aethiopicus) in Algeria.

Effect of Salinity and Water Stress on the Essential Oil Components of Rosemary (Rosmarinus officinalis L.)

Endoparasites (helminths and coccidians) in the hedgehogs Atelerix algirus and Paraechinus aethiopicus from Algeria

Effet du climat et de l’exposition sur la dynamique des populations de la cochenille violette, Parlatoria oleae Colvée (Hemiptera : Diaspididae), en conditions arides

The population structure, age and growth of Luciobarbus callensis (Cyprinidae) in a man-made lake in the Maghreb (NE Algeria)