J. Med. Entornol. 34(5): 511-516 (1997) ABSTRACT From 1989 to 1992. a longitudinal study of the relationships between different tick species and domestic ungulates in the transmission and amplification of Crimean-Congo hemorrhagic fever (CCHF) virus was undertaken in the Bandia area in Senegal where the presence of the virus had been reported previously. An epizootic occurred in 1991-1992 and 22 strains of CCHF virus were isolated from Hyalomma marginatum rufipes Koch, Amblyomma variegatll1n (F.), Rhipicephalus gUilhoni Morel & Vassiliades. and R. evertsi ecertst Neumann ticks collected from cattle and goats. No human cases were reported. Transmission of CCHF virus in the area involves a complicated pattern including many tick species and hosts. Arnphcons of the S fragment (,536 bp) of the CCHF genome of 12 isolates from the study were obtained by polymerase chain reaction and analyzed by restriction-length fragment polymorphism, Three different genotypes of CCHF virus were identified and present during the epizootic, One genotype was recovered from A. oariegatum. R. gUilhoni. and R. e. ecertsi and 2 genotypes were isolated from H, rn, rufipes,

A wide variety of viral infectious diseases are transmitted to humans by ticks and in certain cases, theses diseases can lead to a severe encephalitis or haemorrhagic fever. Within the framework of a research programme on emerging viral diseases carried out by the French Institute of Research for the Development (Institut de Recherche pour le Developpement, IRD) in partnership with the Centre for Vectors and Vector-borne Diseases, Mahidol University (Thailand), the spatial distribution of ticks in Thailand was investigated. An exhaustive review of studies of acarology conducted over the 20th century on Thailand was completed. We derived from this review the geographic coordinates of sites where ticks were collected in the past. In complement, we realised field works to collect ticks on unexplored sites. The location of theses sites was obtained with a GPS (Global Positioning System). Hence, we were able to build up a location-based inventory of ticks covering almost the whole Thailand. These data were then processed in a GIS to assess in every region the presence of tick species and to map the distribution of species known as potential vectors of viruses which are likely to be pathogenic to humans. All the GIS processings were undertaken using SavGIS©, a GIS freeware developed by IRD. This research represents a starting point for assessing tick-borne virus spread and the related risk of zoonosis in Thailand.

Un etat des lieux est rapporte sur les isolements du virus de la Fievre Hemorragique de Crimee Congo (CCHF) de tiques et la seroprevalence en anticorps IgG chez l'homme et les moutons au Senegal. Ces donnees sont correlees aux variations d'abondance relative des especes potentiellement vectrices. Quelques informations sont egalement rapportees sur la seroprevalence de l'ehrlichiose bovine a Ehrlichia ruminantium. Cette repartition spatiale par zone ecologique des donnees relatives a l'epidemiologie de la FHCC et de l'ehrlichiose bovine a Ehrlichia ruminantium permet de faire une cartographie actualisee de ces 2 maladies a tiques au Senegal et de suivre leur evolution dans l'espace et dans le temps.

This chapter contains sections titled: Foreword From Nosology to Concept Tools and Strategies: An Integrative Approach Emergence of Exemplary Diseases or Systems Concluding Remarks Acknowledgments References

Ticks are known vectors of transmission for a number of infectious viral diseases from wild or domestic animals to humans. Many tick-borne diseases cause severe clinical syndromes such as encephalitis or hemorrhagic fever. Animal carriers of enzootic diseases are often asymptomatic. Within the framework of a program to monitor emerging viral diseases in Southeast Asia, identification of ticks capable of transmitting diseases from animals to man is a prerequisite for epidemiologic study to assess the risk of tick-borne disease. The purpose of this report is to provide an update on the situation based on a study of tick fauna in the central plain area of Thailand and on current knowledge about tick-borne arboviruses in Asia. In addition to an exhaustive inventory of ticks found in Thailand, this study describes the viruses with pathogenic potential that ticks are known to carry and transmit to man. A perusal of the literature allowed initial assessment of the risk for introduction and spread of ticks by bird hosts in Southeast Asia as well as of associated virus.

Une liste de la faune des Argasidae du Senegal est dressee. Elle comprend 11 especes (six Argasinae et cinq Ornithodorinae). Argas (A.) hermanni, A. (Persicargas) persicus et A. (P ) proche de walkerae sont presents dans les poulaillers. Argas (P.) arboreus et Argas (P ) streptopelia sont respectivement associes aux aigrettes et aux tourterelles dans differentes zones ecologiques du Senegal. Carios (C. ) vespertilionis est trouve associe aux chauves-souris insectivores des genres Tadarida, Taphozous, Scotoecus, Scotophilus et Pipistrellus. Alectorobius (Reticulinasus) camicasi infeste les chauves-souris frugivores du genre Rousettus, Alectorobius (A.) maritimus est present dans les sites de nidification des sternes du Parc National de la Langue de Barbarie (PNLB) et A. (A.) capensis est egalement associe aux sternes du meme parc et aux pelicans du Parc National des Oiseaux du Djoudj (PNOD). A. (Theriodoros) sonrai, infeode aux terriers des rongeurs Sciuromorphes et Myomorphes, est largement distribue au Senegal ; Ornithodoros (O.) savignyi est localise au Nord du Senegal, dans les endroits sablonneux, sous les arbres aux alentours des forages. Deux autres especes, dont la position systematique reste a elucider, sont connues de nids de pelicans au Parc du Djoudj et de microchiropteres en zone soudano-sahelienne. Argas (Persicargas) proche de walkerae et O. (O.) savignyi sont repertories au Senegal pour la premiere fois. La presence d'A. (A. ) maritimus au Senegal est confirmee. Les hotes communs et accidentels sont signales.

Ticks are of considerable medical and veterinary importance because they directly harm the host through their feeding action and indirectly through vectoring many bacterial pathogens. Despite many ticks being known from Thailand, very little is known about the bacteria they may harbor. We report here the results of a survey of tick-associated bacteria in Thailand. A total of 334 individuals representing 14 species of ticks in five genera were collected from 10 locations in Thailand and were examined for the human pathogens, Borrelia, Francisella, Rickettsia, and the common arthropod endosymbionts, Wolbachia, by polymerase chain reaction (PCR) assay using specific primers. Rickettsial DNA was detected in 30% (9/30) of Amblyomma testudinarium (Koch, 1844) collected from Khao Yai National Park, Nakhon Nayok Province and 16.84% (16/95) of Hemaphysalis ornithophila (Hoogstraal and Kohls, 1959) collected from Khao Yai National Park, Nakhon Nayok Province and Khao Ang Rue Nai Wildlife Sanctuary, Chachoengsao Province. Rickettsial DNA was not detected in any of the other tick species and no DNA of Borrelia, Francisella, or Wolbachia was detected in any of 14 tick species. Phylogenetic relationships among the rickettsiae detected in this study and those of other rickettsiae were inferred from comparison of sequences of the 17-kDa antigen gene, the citrate synthase gene (gltA), and the 190-kDa outer membrane protein gene (ompA). Results indicated that the three Thai rickettsiae detected in this study represent new rickettsial genotypes and form a separate cluster among the spotted fever group rickettsiae.

ABSTRACT A total of 650 ticks, including 13 species from five genera, were collected from animals, from people, or by flagging of the vegetation at sites on the Thai-Myanmar border and in Vietnam. They were tested by PCR to detect DNA of bacteria of the order Rickettsiales . Three Anaplasma spp. were detected in ticks collected in Thailand, including (i) Anaplasma sp. strain AnDa465, which was considered a genotype of Anaplasma platys (formerly Ehrlichia platys ) and which was obtained from Dermacentor auratus ticks collected from dogs; (ii) Anaplasma sp. strain AnAj360, which was obtained from Amblyomma javanense ticks collected on a pangolin; and (iii) Anaplasma sp. strain AnHl446, which was closely related to Anaplasma bovis and which was detected in Haemaphysalis lagrangei ticks collected from a bear. Three Ehrlichia spp. were identified, including (i) Ehrlichia sp. strain EBm52, which was obtained from Boophilus microplus ticks collected from cattle from Thailand; (ii) Ehrlichia sp. strain EHh324, which was closely related to Ehrlichia chaffeensis and which was detected in Haemaphysalis hystricis ticks collected from wild pigs in Vietnam; and (iii) Ehrlichia sp. strain EHh317, which was closely related to Ehrlichia sp. strain EBm52 and which was also detected in H. hystricis ticks collected from wild pigs in Vietnam. Two Rickettsia spp. were detected in Thailand, including (i) Rickettsia sp. strain RDla420, which was detected in Dermacentor auratus ticks collected from a bear, and (ii) Rickettsia sp. strain RDla440, which was identified from two pools of Dermacentor larvae collected from a wild pig nest. Finally, two bacteria named Eubacterium sp. strain Hw124 and Eubacterium sp. strain Hw191 were identified in Haemaphysalis wellingtoni ticks collected from chicken in Thailand; these strains could belong to a new group of bacteria.

De nouvelles observations sur la bioecologie de tiques collectees dans sept provinces thailandaises sont presentees a partir de recoltes continues realisees de juin a decembre 1998.

We have conducted experiments to assess the ability of Rhipicephalus evertsi evertsi tick to transmit the Crimean-Congo haemorrhagic fever (CCHF) and determine their reproductive cycle. The Rh. e. evertsi was infected by intracoelomic (transparietal and intra-anal) inoculation during the imaginal stases and by oral feeding on an infected viremic goat during imaginal and nymphal stases. The infection rate, transovarial and trans-stasial CCHF virus transmission were monitored for virus reisolation after suckling mice inoculation and the virus identified by ELISA and IFA for antigen detection. After intracoelomic inoculation, unfed adults had viral titers ranging from 0.67 to 2.9 log DL50/0.02 ml and had transmitted the virus to their vertebrate hosts by blood feeding. After 8 to 10 days of blood feeding duration, infection rates were respectively 36% and 100% for male and female ticks. In two instances out of seven transovarial transmission was observed and the virus reisolated from larvae of first generation. However, the virus was not detected after nymphal metamorphosis. After blood feeding on viremic goats, 71% of the nymphae were infected. After metamorphoses 22% of the males and 42% of the females had a low virus titer. Rh. e. evertsi appears to have a limited efficacy in transmitting and replicating the CCHF virus but must be not neglected as a potential vector during an epizootic manifestation.

In this article, we published the role of three species of ticks Amblyomma variegatum (Fabricius, 1974), Hyalomma marginatum rufipes (Koch, 1844) and Hyalomma truncatum (Koch, 1844) in the maintenance and transmission of the CCHF virus. The imagos of these species were infected by intracoelomic route. Vertical transmission (transtasial and transovarial) and horizontal transmission for different stases were studied by isolation on newborn mice, polymerase chain reaction, indirect immunofluorescence and ELISA. Our results proved that 15 days after inoculation, infection rates of 100% were noted with Hyalomma marginatum rufipes and Hyalomma truncatum. This rate is about 60% for Amblyomma variegatum. The imagos of the three species infected have transmitted the virus to their host during blood feeding (100%). A high transovarial transmission for Hyalomma marginatum rufipes and Hyalomma truncatum were observed (respectively 53 and 50%). This rate is about 12% for Amblyomma variegatum. The tick infection does not persist up to the first generation for the three species studied. Ticks are temporary reservoirs vectors but not permanent reservoirs of CCHF virus.

In this article, we published the role of three species ei ticks Amblyomma variegatum (Fabricius, 1974), Hyalomma marginatum rufipes (Koch, 1844) and Hyalomma truncatum (Koch, 1844) in the maintenance and transmission of the CCHF virus. The images of these species were infected by intracoelomic route. Vertical transmission (transtasial and transovarial) and horizontal transmission for different stases were studied by isolation on newborn mice, polymerase chain reaction, indirect immunofluorescence and ELISA.Our results proved that 15 days after inoculation, infection rates of 100 % were noted with Hyalomma marginatum rufipes and Hyalomma truncatum. This rate is about 60 % for Ambiyommo variegatum. The images of the three species infected have transmitted the virus to their host during blood feeding (100 %). A high transovarial transmission for Hyalomma marginatum rufipes and Hyalomma truncatum were observed (respectively 53 and 50 %). This rate is about 12 % for Amblyomma variegatum. The tick infection does not persist up to the first generation for the three species studied. Ticks ore temporary reservoirs vectors but not permanent reservoirs of CCHF virus.

West African sheep appear to play a central role as virus hosts in the maintenance cycle of Crimean-Congo haemorrhagic fever (CCHF) virus in endemic areas and also because of their role as a principal host of the CCHF virus tick vector. In an effort to clarify CCHF epidemiological significance in sheep, we studied the biological and clinical aspects of sheep experimentally infected with CCHF virus. West African sheep breeds were infected either by intraperitoneal inoculation or by infestation with experimentally CCHF-virus-infected ticks (Hyalomma truncatum). A total of 17 sheep including controls as well as 5 lambs from their progeny were monitored. A moderate but constant fever was observed (39.7 degrees C +/- 0.3) which correlates with the viraemia. Virus was reisolated from blood samples taken from day 3 to day 9 postinfection (p.i.) at a mean titre of 3.3 log LD50/ml. The virus was detected for a period of time of 7 days in non-immune sheep and for less than 4 days in previously immunized sheep. In non-immune sheep, antibody detected by ELISA showed an IgM response on day 7 p.i., followed by an IgG response one day later. Five infected sheep, surveyed for liver and kidney biological markers, showed hepatic dysfunction with a moderate serum aspartate transferase rise to 210 U/l. Out of four sheep tested for blood markers, two showed an abnormal blood cell count, with marked neutrophilia of up to 63% lasting for two weeks. Infected pregnant ewes produced antibodies in their milk at a significant titre (1:1,000), and antibodies were recovered in the sera of nursing lambs from their first meal to 50 days after birth. These findings are discussed; they demonstrate that, in spite of a high turnover of local sheep herds (median age of 3 years) and long-term CCHF antibody persistence (> 3 years), sheep can be infected and efficiently transmit the virus at least once in a lifetime.

A new tick species - Alectorobius (Reticulinasus) camicasi n. sp., a parasite of fruit bats, Rousettus aegyptiacus occidentalis, in Senegal - is described. This new species is based on laboratory reared males, females, nymphs and larvae. Alectorobius (Reticulinasus) camicasi n. sp. is closely related to the two other African species: Alectorobius (Reticulinasus) salahi (Hoogstraal, 1953), a parasite of the fruit bat Rousettus aegyptiacus (Geoffroy) in Egypt; and Alectorobius (Reticulinasus) faini (Hoogstraal, 1960), a parasite of Rousettus leachii (Smith) in the Congo. The new Senegalese species is easily distinguished from the Egyptian species by shape of dorsal surface of idiosoma of adults, coral setae and hypostomal formula of the larva. It is very similar to the Congolese species, but differs from it by the appearance of the antero-dorsal surface-of idiosoma of male, and by the hypostomal formula, dorsal plate, length of fourth palpal article, and the position and distance between some setae of the larva.

From 1989 to 1992, a longitudinal study of the relationships between different tick species and domestic ungulates in the transmission and amplification of Crimean-Congo hemorrhagic fever (CCHF) virus was undertaken in the Bandia area in Senegal where the presence of the virus had been reported previously. An epizootic occurred in 1991-1992 and 22 strains of CCHF virus were isolated from Hyalomma marginatum rufipes Koch, Amblyomma variegatum (F.), Rhipicephalus guilhoni Morel & Vassiliades, and R. evertsi evertsi Neumann ticks collected from cattle and goats. No human cases were reported. Transmission of CCHF virus in the area involves a complicated pattern including many tick species and hosts. Amplicons of the S fragment (536 bp) of the CCHF genome of 12 isolates from the study were obtained by polymerase chain reaction and analyzed by restriction length fragment polymorphism. Three different genotypes of CCHF virus were identified and present during the epizootic. One genotype was recovered from A. variegatum, R. guilhoni, and R. e. evertsi and 2 genotypes were isolated from H. m. rufipes.

The ixodid fauna of rodent burrows in the Bandia area was studied. From May 1987 to April 1988, 1794 ticks were collected, mostly immature and mature A. sonrai (98,2%). This tick species is present all year round, without significant seasonal variations. The development cycle of 110 days was determined in the laboratory. Three CCHF virus isolates were obtained from this tick species. However, CCHF transmission experiments strongly suggest that A. sonrai is not a vector of CCHF virus.