RICKETTSIA AND ENVIRONMENT (FIGURE )

The ecology of rickettsiae is clearly linked to environmental factors as vector-borne pathogens. Mumcuoglu et al.(1993) investigated an outbreak of spotted fever group rickettsiae (SFGR) in a small settlement located in southern part of Israel. The settlement Kibbutz Zeelim (Z), the main source of SFGR with high morbidity was compared to another settlement of equal magnitude (Kibbutz Reim, R) located only 20 km away, as control. The dominant tick species isolated from site Z was Rhipicephalus sanguineus and from site

2.19.1Rickettsialzoonoticdiseasesandtheirglobaldistribution. AgentGeographical DistributionHostsandreservoirsVectors mountainspotted (RMSF)RickettsiarickettsiiUSA,Canada,Costa Rica,Mexico,Panama, Columbia,Brazil Rabbit,fieldmice,flying squirrel,otherrodents andticks

Dermacentorvariabilis, D.andersonii, Rhipicephalus sanguine,Amblyomma cayennense Spotted (MSF), fever

RickettsiaconoriiSouthernEurope, Morocco,Israel, Georgia,Ethiopia, Kenya,SouthAfrica, India,Pakistan

Dogs,rodentsandticksRhipicephalussanguine Russia,China,Pakistan EasternAustralia Rickettsiasibirica FlindersIsland (Australia) RickettsiaaustralisGuadeloupe,eastern sub-SaharanAfrica RickettsiahoneiFrance,Slovakia RickettsiaafricaeJapan Rickettsiaslovaca Rickettsiajaponica TyphusRickettsiaprowazekiiEthiopia,Sudan, Somalia,Uganda, Kenya,Burundi, Rwanda,Mexico, Colombia,Peru,Bolivia, countriesofformer USSRandsomeUS states Humans,flyingsquirrelsHumanbodylouse (Pediculushumanus corporis),Flea (Orchopeashowardii)

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MurineTyphus, EndemicTyphus,Toulon Typhus,Tabardillo Rickettsia typhiRickettsiafelisYugoslavia,Greece, Malta,Sicily,USA (California,Texas)

Rats,urbanOpossumRatfleas(Xenopsylla chopis,Leptopsylla segnis),Catflea (Ctenocephalidesfelis) QFeverCoxiellaburnetii(nowa separatedgenusofthe familyRickettsiaceae)

Worldwide(exceptNew Zealand)Rodents,birds,game, domesticanimals(e.g. cattle),ticksandhumans

Airborneinfecteddust, aerosols,direct/indirect contactwithinfected animalsortheirexcreta, possiblydairyinfected products Potentialhuman zoonosesagentsnotyet isolatedfromhumansa,b

Rickettsia montanaRickettsia parkeriRickettsia massiliaeRickettsia rhipicephalisRickettsia helveticaRickettsia aeschlimannii

Montana(USA),Swiss, Spain?? RickettsialpoxRickettsiaakariNewYork(USA),former USSR,Croatia, SouthernEurope, Korea,SouthernAfrica

Mice,mitesBloodsuckingmite (Liponyssoides sanguineus) ScrubTyphus (tsutsugamushifever)OrientiatsutsugamushiEastAsia,Pacific Islands,Northern Australia

Rats,mice,rabbits, marsupialsMites(Trombicolaspp.) a Tijsse-Klasen,E.,Fonville,M.,vanOverbeek,L.,Reimerink,J.Hj.&Sprong,H.(2010)ExoticRickettsiaeinIxodesricinus:factorartifact?.ParasitVectors 3,54. b Oteo,J.A.,Portillo,A.,Blanco,J.R.,Ibarra,V.,Pérez-Martínez,L.etal.(2005)LowriskofdevelopinghumanRickettsiaaeschlimanniiinfectioninthenorthof Spain.Ann.N.Y.Acad.Sci.1063,349–351.

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R,R. turanicus Pomerantzev. Physical factors such as soil composition and ambient surface temperatures that may clarify these differences were studied. Indeed, site Z had higher maximum soil and ambient temperatures well correlated with a higher tick load for a longer time span. Dogs, sheep, goats and various rodents were more heavily infested with ticks on site Z than on site R, while interestingly both sites were equal in dogs and mice’ seropositivity to SFGR. Both sites had dogs as pet animals; however, site Z revealed that 7.1% of dog owners acquired Mediterranean spotted fever compared with only 1.4% of people without dogs. Population education and natural growth decline can prevent infections, in the particular case of rickettsiosis that has a familial character with close contact (louse-borne). Onishchenko et al.(1997) emphasized the decrease of louse-borne typhus in Russia due to natural demographic processes.

As rodents are one of the main reservoirs of Rickettsia, Norway rats were surveyed for zoonotic pathogens in the Baltimore area, USA. Antibodies against Rickettsia typhi were detected in 7.0%

of the live-trapped rats (Easterbrook et al., 2007). Beside rodents a Japanese researcher reported detection of Rickettsia in association with seabirds suggesting a broader environmental circulation by Figure 2.19.1. ZoonoticRickettsiaspp. proved and potential environmental life

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In a study performed in Russia (Leningrad province), cattle were shown to be the main source ofCoxiella burnetii infection in humans (Tokarevich et al., 2006). These authors showed that livestock farming modifications may impact infection with Q-fever. Over a period of 10 years, a reduction in large specialized livestock farms (subject to more advanced veterinary monitoring) occurred concomitantly with an increase in small private farms, exposing cattle to uncontrolled migration and contact with non-professional population, consequently increasing the health risk from this pathogen’s transmission. It should be mentioned at this point that the C. burnetii is highly infectious requiring as few as one organism to cause disease via inhalation in susceptible humans (Sanderset al.,2008). In addition, these authors observed a dramatic rise in domestic dogs carrying C. burnetii (based on seroprevalence) especially in urban areas (cities). In relation to dog population, Mannelliet al.(2003) in Piemonte (Italy) reiterated that link through R. conorii seropositivity observed in surveyed dogs, concluding that a relatively high dog population density within a rural or semi-rural environment encourages emergent foci of Mediterranean spotted fever (MSF) in this area. A related trend was also reported in Okinawa (Japan) supporting the above result (Satohet al., 2001).

Vector-borne diseases such as Boutonneuse fever were found to be also associated to climate change.

Portuguese researchers looked at the endemic pathogen R. conorii (the strain involved in Malish and Israeli spotted fever) transmitted by the brown dog tick (Rhipicephalus sanguineus) and seroconversion during the off-season months (October-February) for a period of 6 years (2000–2005) (de Sousaet al., 2006). They found a significant increase in positive cases, evidently related epidemiologically to climate change expressed in low precipitation values. The main factorial argument for this increase was the milder climate, permitting vectors such as ticks and other arthropods to survive and multiply preferentially. Vescio et al. (2008) looked at climatic factors that may correlate with mediterranian spotted fever (MSF) cases in the northern part of Sardinia and found that exposure to high temperature during summer months in a given year may increase MSF incidence in the following year. These authors explained their results based on the biology of tick vector life cycle.

Previous reports ofRickettsia typhishowed that lower temperatures than that of the human body are favorable for this pathogen and possibly for its other relatives. Moragues and Pinkerton (1944) subjected two groups of laboratory dba mice strain to murine typhus rickettsiae at two different temperature ranges: 18.3–22.7°C and 29.4–36.6°C and monitored illness and fatality. At lower temperatures the fatality was 100% and only,25% at higher temperatures.

In the USA, reported infections with epidemic typhus rickettsiae (Rickettsia prowazekii) were not associated with the classic man-louse-man cycle of epidemic typhus, but related to contact with flying squirrels (McDadeet al., 1980). A ten year study in the French Alps showed that human activity such as deforestation, can enhance the spread of certain ticks species from forested to urban areas, creating new or expanding known foci of disease transmission in the vicinity of large cities (Gilot and Pautou, 1982).

Wanget al., (2004) described a new symbiont bacterium (provisional name“CandidatusHepatincola porcellionum”) that densely colonizes the midgut glands (hepatopancreas) of a terrestrial isopod (P. scaber). Isopods are an order of peracarid crustaceans, including commonly known animals such as woodlice and pill bugs. Based on comparative sequence analysis of 16S rRNA they classified this new bacterium as a distant relative of the order Rickettsiales (group known as intracellular symbionts and pathogens in many animals).

Another group of researchers analysed the genome of Rickettsiella grylli, an intracellular parasite of grasshoppers and the closest known phylogenetic relative of theCoxiella group (Seshadri and Samuel, 2005). Genomic proximity of crustacean and arthropods symbionts and pathogens suggests a broad evolutionary pattern of transition from symbiotic to pathogenicity and obligatory virulence in intracellular life.

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An indication of a possible evolutionary pathway of an endosymbiont phylogenetically related to the order Rickettsiales, came from the protozoa Acanthamoeba spp. Considering the long-standing relationship of most Rickettsiales with arthropods, the related lineage of endosymbionts in protozoan hosts has had implications in the preadaptation and/or recruitment of rickettsia-like bacteria into metazoan hosts and further to invertabrates (Fritscheet al., 1999).

Another fascinating interaction was described in a linyphiid spiders E. atra, that persists in heterogeneous environments because of its ability to recolonise areas through active long-distance airborne dispersal using silk as a sail, in a process termed“ballooning”. However, a Rickettsia species endosymbiont that colonizes the sub-oesaophageal ganglion of this spider impairs the ballooning process. As mentioned earlier, in the case ofY. pestisand its“blocking mechanism”exercised on fleas, it is clear that this“biochemical behavior”outcome helps the pathogen to spread and infect new hosts, but in the present case of thisRickettsiasp. the ecological gain is not clear from the endosymbiont point of view and it might be that it is simply an“induced disease”through its activity on the sub-oesaophageal ganglion of this spider, unrelated directly to its ecology (Goodacreet al., 2009).

Among the insects involved in transmission of Rickettsial disease, Hucko (1984) showed that house fly fed withCoxiella burnettisuspension keep their infectivity throughout their life (∼32 days) and possibly contaminate the environment during this time interval. The author also found thatC. burnetiican survive in the fly’s feces for 80 days and in dead flies as long as 90 days, therefore constituting a real health risk asC. burnettiis known to be airborne transmitted.

Finally, there are an increasing number of reports on Rickettsia like organisms in plants connected with phytopathogenesis (Hopkins and Mollenhauer, 1973). Whether they belong to theRickettsiaorder is not clear (Evert et al., 1981); however, Davis et al. (1998) using comparative sequence analyses, showed that papaya bunchy top disease is caused by a bacterium that is a member of the genus Rickettsia.

Applying PCR method, they detected this bacterium only in diseased plants but not in healthy ones as the first evidence of genus Rickettsia as a potential plant pathogen.

2.19.2 REFERENCES

Davis, M.J., Ying, Z., Brunner, B.R., Pantoja, A. & Ferwerda, F.H. (1998) Rickettsial relative associated with papaya bunchy top disease.Curr. Microbiol.36, 80–84.

De Sousa, R., Luz, T., Parreira, P., Santos-Silva, M. & Bacellar, F. (2006) Boutonneuse fever and climate variability.

Ann. N.Y. Acad. Sci.1078, 162–169.

Easterbrook, J.D., Kaplan, J.B., Vanasco, N.B., Reeves, W.K. Purcell, R.H.et al.(2007) A survey of zoonotic pathogens carried by Norway rats in Baltimore, Maryland, USA.Epidemiol. Infect.135, 1192–1199.

Evert, D.R., Gaines, T.P. & French, W.J. (1981) Rickettsia-like bacteria in peach roots preceded development of visual symptoms of phony peach disease and changes in leaf elemental concentrationsJ. Am. Soc. Hortic. Sci.106, 780–782.

Fritsche, T.R., Horn, M., Seyedirashti, S., Gautom, R.K., Schleifer, K-H. & Wagner, M. (1999) In situ detection of novel bacterial endosymbionts ofAcanthamoebaspp. phylogenetically related to members of the order Rickettsiales.

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Gilot, B. & Pautou, G. (1982) Evolution of populations of ticks (Ixodidae and Argasidae) in relation to artificialization of the environment in the French Alps. Epidemiologic effects.Acta Trop.39, 337–354.

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Hucko, M. (1984) The role of the house fly (Musca domesticaL.) in the transmission ofCoxiella burnetii. Folia Parasitol.31, 177–181.

Kawabata, H., Ando, S., Kishimoto, T., Kurane, I., Takano, A.et al.(2006) First detection of Rickettsia in soft-bodied ticks associated with seabirds, Japan.Microbiol. Immunol.50, 403–406.

Mannelli, A., Mandola, M.L., Pedri, P., Tripoli, M. & Nebbia, P. (2003) Associations between dogs that were serologically positive for Rickettsia conorii relative to the residences of two human cases of Mediterranean spotted fever in Piemonte (Italy).Prev. Vet. Med.60, 13–26.

McDade, J.E., Shepard, C.C., Redus, M.A., Newhouse, V.F. & Smith, J.D. (1980) Evidence ofRickettsia prowazekii infections in the United States.Am. J. Trop. Med. Hyg.29, 277–284.

Moragues, V. & Pinkerton, H. (1944) Variation in morbidity and mortality of murine typhus infection in mice with changes in the environmental temperature.J. Exp. Med.79, 41–43.

Mumcuoglu, K.Y., Frish, K., Sarov, B., Manor, E., Gross, E.et al.(1993) Ecological studies on the brown dog tick Rhipicephalus sanguineus (Acari: Ixodidae) in southern Israel and its relationship to spotted fever group rickettsiae.J. Med. Entomol.30, 114–121.

Onishchenko, G.G., Lukin, E.P. & Syskova, T.G. (1997) A prognostic assessment of louse-borne typhus (Rickettsia prowazekiiinfection) in Russia.Zh. Mikrobiol. Epidemiol. Immunobiol.6, 30–36.

Salgo, M.P., Telzak, E.E., Currie, B., Perlman, D.C., Litman, N.et al.(1988) A focus of Rocky Mountain spotted fever within New York City.N.Engl. J. Med.318, 1345–1348.

Sanders, D.M., Parker, J.E., Walker, W.W., Buchholz, M.W., Blount, K.et al.(2008) Field Collection and genetic classification of tick-borne rickettsiae and rickettsiae-like pathogens from south Texas: Coxiella burnetii isolated from field-collectedAmblyomma cajennense. Ann. N.Y. Acad. Sci.1149, 208–211.

Satoh, H., Tsuneki, A., Inokuma, H., Kumazawa, N., Jahana, Y.et al.(2001) Seroprevalence of antibodies against spotted fever group rickettsia among dogs and humans in Okinawa, Japan.Microbiol. Immunol.45, 85–87.

Seshadri, R. & Samuel, J. (2005) Genome analysis ofCoxiella burnetiispecies insights into pathogenesis and evolution and implications for biodefense.Ann. N.Y. Acad. Sci.1063, 442–450.

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Vescio, M.F., Piras, M.A., Ciccozzi, M., Carai, A., Farchi, F.et al.(2008) Short report: socio-demographic and climatic factors as correlates of mediterranean spotted fever (msf ) in northern Sardinia.Am. J. Trop. Med. Hyg. 78, 318–320.

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Chapter 2.20 Salmonelloses

[SALMONELLASPP.]

Salmonella is a genus closely related to Escherichia genus, both members of the extended family of Enterobacteriaceae. Salmonella is a rod-shaped, gram-negative, facultative anaerobic, non-spore forming, predominantly motile (with peritrichous flagella) bacterium. Salmonella was isolated worldwide from both cold- and warm-blooded animals (including humans) and environments contaminated with hosts’ excreta. Salmonella carried by animals (as residents of the GI tract) is transmitted to humans by direct contact but the vast majority of human cases are acquired through ingestion of contaminated food and water.Salmonellanomenclature is still evolving, but the main species are listed in Table 2.20.1 (Brenner et al., 2000; Su and Chiu, 2007). In terms of time, the disease manifests itself relatively fast (from 5 to 72 hours) and depends on virulence and number of bacteria ingested (typically high numbers as a result of overgrow in food environment). The symptoms are: sudden nausea, vomiting and watery diarrhea that may contain blood, and fever (∼39°C). Complications can occur mainly in immunocompromised patients for example: meningitis, septicemia, osteomyelitis, arthritis, peritonitis, urinary tract infection (UTI) and endocarditis. In animals it expresses as acute gastroenteritis or is silent (carrier state in reptiles).