Difference In Prevalence Of Infection Research Articles

Survey of Sarcocystis Species Infection in Slaughtered Goats in Makurdi Metropolis

The emerging zoonotic infection caused by Sarcocystis species is becoming a serious public health problem for animal rearers .This study was conducted to determine the prevalence of Sarcocystis species infection in slaughtered goats at some selected abattoirs in Makurdi metropolis. Histological investigation was carried out using Haematoxylin and Eosin (H and E) as the staining agent on the tissue samples of heart (21), oesophagus (191) and tongue (183) from 224 goats. The results showed that, out of the 224 goats examined, 84(37.50%) were observed to be infected with Sarcocystis species. Morphologically some appeared round, ovoid or globular while others were elongated, spindle-shaped that tapered at one end. Infection related to sex showed that females had higher (83.33%) rate than males (16.67%).With respect to infection due to age, 9.52, 28.57 and 61.91% for ages 1-2 years, 2-3 years and above 3 years respectively were noted. Sex and age of the animals were not determining factors of the infection (P>0.05).There was significant difference in prevalence of infection in the three muscular tissues examined, with oesophagus having the highest (63.10 %) followed by the tongue (34.52%) and heart being the least (2.38%) (P< 0.05). The presence of two distinct microscopic cyst shapes (elongated, spindle-shaped that taper at one end and the round, oval or globular form) prompts the need for further research to ascertain species-specific associated with this parasite in goats and other animals in Nigeria.

Occurrence of microsporidians Glugea hertwigi and Pleistophora ladogensis, in smelt Osmerus eperlanus from two German rivers, North Sea coast.

Monthly samples of smelt Osmerus eperlanus (Linnaeus, 1758) were collected from July 1985 to May 1986, in the river Elbe (Germany), and examined for infections with microsporidians. Two microsporidians were found: Glugea hertwigi Weissenberg, 1911, infecting the digestive tract and Pleistophora ladogenis Voronin, 1978, infecting the skeletal musculature. G. hertwigi infection led to the formation of xenomas, whereas P. ladogensis was characterized by diffuse infections, with the production of macroscopic visible thread-like or oval-shaped infection foci. Development of G. hertwigi in the host cells showed characteristics typical of the genus Glugea. The ultrastructural development of P. ladogensis showed features typical of the genus Pleistophora, without evidence of the production of 2 types of spores. Host reaction consisted of inflammatory tissue surrounding some of the infection foci as well as phagocytosis of spores. G. hertwigi was only found in juvenile smelt (<10 cm in length), whereas P. ladogensis infected smelts from 6 to 26 cm in length. Prevalence increased with fish length to a maximum value of 9.6%. Seasonal fluctuations in prevalence of infection were also found, with the lowest value in the winter months (2.5% in January 1986) and the highest in summer (11.8% in July 1985). The differences in prevalence of infection with fish length and date of sampling were significant. Additionally, samples of smelt caught in April 1986 from the rivers Eider and Ems revealed infections with P. ladogensis in the first river system only.

Baseline prevalence and intensity of schistosomiasis at sentinel sites in Madagascar: Informing a national control strategy.

BackgroundSchistosomiasis affects more than 800 million people, mostly in sub-Saharan Africa. A baseline sentinel site study was conducted in the Western half of Madagascar to determine the prevalence and intensity of schistosomiasis and soil-transmitted helminth (STH) infections prior to mass drug administration, and to explore the associations between infection and school attendance, and access to water, sanitation and hygiene (WASH) facilities.MethodsA three-stage, cluster-randomised cross-sectional study was conducted in 29 sentinel sites in October 2015. Twenty school attending and 4 non-attending children in each of the age groups from 7 to 10 years old were randomly selected at each site for detection of Schistosoma haematobium eggs in a single urine slide by filtration, and of S. mansoni, Ascaris lumbricoides, Trichuris trichiura and hookworm eggs in duplicate Kato-Katz slides from a single stool sample. School attendance was registered individually, and school-level access to WASH facilities was scored through pre-defined observed and reported factors. Logistic regression analysis was performed, adjusting for gender, age and study site. School-level WASH status was analysed using Spearman’s rank correlation coefficient.ResultsA total of 1,958 children were included. The prevalence of S. haematobium infection and heavy-intensity infection was 30.5 % and 15.1 %, respectively. The prevalence of S. mansoni infection and heavy-intensity infection was 5.0 % and 0.9 %, respectively. The prevalence of any STH infection was 4.7 %. There was no significant difference in prevalence of infection or heavy-intensity infection of either schistosome species between attending and non-attending children, apart from heavy-intensity S. mansoni infection that was significantly more common in children who did not attend school regularly (aOR = 7.5 (95 % CI = 1.1-49.5); p = 0.037). Only a minority of schools had adequate access to WASH facilities, and in this study, we found no significant association between school-level WASH status and schistosomiasis.ConclusionsThis study found an alarmingly high prevalence and intensity of schistosomiasis, and the results warrant urgent scale-up of the national NTD control programme that will need to include both non-attending and attending school-age children in order to reach WHO roadmap targets for the control of schistosomiasis by 2020.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1337-4) contains supplementary material, which is available to authorized users.

Parasites of Trinidadian guppies: evidence for sex- and age-specific trait-mediated indirect effects of predators.

Predation pressure can alter the morphology, physiology, life history, and behavior of prey; each of these in turn can change how surviving prey interact with parasites. These trait-mediated indirect effects may change in direction or intensity during growth or, in sexually dimorphic species, between the sexes. The Trinidadian guppy, Poecilia reticulata presents a unique opportunity to examine these interactions; its behavioral ecology has been intensively studied in wild populations with well-characterized predator faunas. Predation pressure is known to have driven the evolution of many guppy traits; for example, in high-predation sites, females (but not males) tend to shoal, and this anti-predator behavior facilitates parasite transmission. To test for evidence of predator-driven differences in infection in natural populations, we collected 4715 guppies from 62 sites across Trinidad between 2003 and 2009 and screened them for ectosymbionts, including Gyrodactylus. A novel model-averaging analysis revealed that females were more likely to be infected with Gyrodactylus parasites than males, but only in populations with both high predation pressure and high infection prevalence. We propose that the difference in shoaling tendency between the sexes could explain the observed difference in infection prevalence between males and females in high-predation sites. The infection rate of juveniles did not vary with predation regime, probably because juveniles face constant predation pressure from conspecific adults and therefore tend to shoal in both high- and low-predation sites. This represents the first evidence for age- and sex-specific trait-mediated indirect effects of predators on the probability of infection in their prey.

Oesophagostomum and Other Strongylid Nematode Infections in Ruminants and Pigs in the Upper East Region of Ghana

Oesophagostomum species are strongylid nematode parasites of monkeys, sheep, goats, pigs, cattle, camels and antelopes. Human infections were considered zoonotic. Studies in the northeastern parts of Ghana suggested that the human infections might be common but focally distributed. Factors determining the focal distribution are not known. The relationship between the human and animal infections is also not known. It is also not known whether the animal infections are focal in distribution. In the present study, two communities known to be endemic to the human infection (Kulbia and Kologo) and two other communities known to be non-endemic to the human infection (Kalbiong and Gbeogo) in the Upper East Region (UER) of Ghana were selected. Prevalences and intensities of Oesophagostomum infection and other related strongylid nematode infections in ruminants and pigs were determined and compared. Faecal samples from cattle, sheep, goats and pigs were collected, processed by coproculture and examined under the microscope for larvae of the different strongylid nematodes. The results show no significant Original Research Article Ahiabor et al.; ARRB, 7(1): 1-22, 2015; Article no.ARRB.2015.101 2 differences in prevalence of infection between the human endemic and human non endemic communities (P = 1.00) during the rainy season and (P =.134) in the dry season. However, there were significant differences in the intensity of infection between the two types of communities only during the dry season (P = .032). Other strongylid nematodes observed were Necator sp., Strongyloides sp. and Trichostongylus sp.

Burden of present-on-admission infections and health care-associated infections, by race and ethnicity

In the United States incidence of sepsis and pneumonia differ by race, but it is unclear whether this is due to intrinsic factors or health care factors. We conducted a study of 52,006 patients hospitalized during 2006-2008 at a referral hospital in upper Manhattan. We examined how the prevalence of present-on-admission and health care-associated infection compared between non-Hispanic blacks, Hispanics, and non-Hispanic whites adjusting for sociodemographic factors, admission through the emergency department, and comorbid conditions. Non-Hispanic blacks had 1.59-fold (95% confidence interval [CI], 1.29-1.96) and 1.55-fold (95% CI, 1.35-1.77) risk of community-acquired bloodstream infection and urinary tract infection compared with non-Hispanic whites. Hispanic patients had 1.31-fold (95% CI, 1.15-1.49) risk of presenting with community-acquired urinary tract infection compared with non-Hispanic whites. Controlling for admission through the emergency department, comorbidity, and neighborhood income attenuated the differences in prevalence of infections. We found that health disparities in present-on-admission infections might be largely explained by potential lack of ambulatory care, socioeconomic factors, and comorbidity.

Prevalence of postpartum infections: a population-based observational study.

We investigated the prevalence of postpartum infections among women giving birth during 1 year in a population-based observational/questionnaire study at seven hospitals in the southeast region of Sweden. Of the women >99% (n = 11,124) received a questionnaire to inquire if they had endometritis, mastitis, or wound, urinary tract or any other infection within 2 months postpartum and whether they received antibiotics for this. Prevalence rates for infections and antibiotic treatment were estimated. The response rate was 60.1%. At least one infectious episode was reported by 10.3% of the women and 7.5% had received antibiotics. The prevalence for infections with and without antibiotics were, respectively, mastitis 4.7% and 2.9%, urinary tract infection 3.0% and 2.4%, endometritis 2.0% and 1.7%, wound infection 1.8% and 1.2%. There was no inter-county difference in infection prevalence. Clinical postpartum infections in a high-resource setting are relatively common.

A comparative study on enteric parasitic infections in immunocompetent and immunosuppressed children in Egypt

Diarrheal diseases are widespread all over the world, not only threaten human health but also greatly affect society and economy. Immune status may affect parasitic infections and the ability to combat such diseases. We aimed to investigate the prevalence of parasitic infections in immunosuppressed pediatric patients in comparison to immunocompetent ones with gastroenteritis. A total of 189 stool samples were collected from 100 immunocompetent diarrheic children at Cairo University Children's Hospitals and 89 children with cancer and diarrhea at the National Cancer Institute (NCI), Cairo University. All cases were subjected to history taking and clinical examination. Stool samples were examined microscopically and by ELISA for Entamoeba histolytica, Giardia lamblia, and Cryptosporidium oocyts. Frequency and duration of both diarrhea and vomiting were significantly higher in immunosuppressed children (P < 0.01). E. histolytica, Giardia, and Cryptosporidium were detected in 2 (1.1 %), 29 (15.3 %), and in 9 (4.8 %) samples, respectively, whereas 46 (24.3 %) cases were positive for other parasitic infections. Overall parasitic infections were positive in 86 stool samples (45.5 %): 41 belonging to immunocompetent patients (41 %) and 45 (50.6 %) to the immunosuppressed group though with no statistically important difference. Parasitic infections in Egyptian children with gastroenteritis are still high. No difference in prevalence of infections between immunosuppressed and immunocompetent children, yet clinical data were statistically higher in immunosuppressed patients (P < 0.01). ELISA is as good as microscopy and is advantageous in its ability to differentiate between E. histolytica and Entamoeba dispar, thus can aid routine labs in detecting parasitic pathogens.

P6.004 The Prevalence of Sexually Transmitted Infections Among Clients of Female Sex Workers in Karnataka, South India: An Analysis by Places of Solicitation of Sex Workers

BackgroundClients of female sex workers (FSWs) are an important bridging population for HIV/STI transmission. Designing client-specific intervention programming faces several challenges, as clients do not comprise one single identifiable group....

Equivalent susceptibility of Anopheles gambiae M and S molecular forms and Anopheles arabiensis to Plasmodium falciparum infection in Burkina Faso

BackgroundThe Anopheles gambiae sensu lato (s.l.) species complex in Burkina Faso consists of Anopheles arabiensis, and molecular forms M and S of Anopheles gambiae sensu stricto (s.s.). Previous studies comparing the M and S forms for level of infection with Plasmodium falciparum have yielded conflicting results.MethodsMosquito larvae were sampled from natural pools, reared to adulthood under controlled conditions, and challenged with natural P. falciparum by experimental feeding with blood from gametocyte carriers. Oocyst infection prevalence and intensity was determined one week after infection. DNA from carcasses was genotyped to identify species and molecular form.ResultsIn total, 7,400 adult mosquitoes grown from wild-caught larvae were challenged with gametocytes in 29 experimental infections spanning four transmission seasons. The overall infection prevalence averaged 40.7% for A. gambiae M form, 41.4% for A. gambiae S form, and 40.1% for A. arabiensis. There was no significant difference in infection prevalence or intensity between the three population groups. Notably, infection experiments in which the population groups were challenged in parallel on the same infective blood displayed less infection difference between population groups, while infections with less balanced composition of population groups had lower statistical power and displayed apparent differences that fluctuated more often from the null average.ConclusionThe study clearly establishes that, at the study site in Burkina Faso, there is no difference in genetic susceptibility to P. falciparum infection between three sympatric population groups of the A. gambiae s.l. complex. Feeding the mosquito groups on the same infective blood meal greatly increases statistical power. Conversely, comparison of the different mosquito groups between, rather than within, infections yields larger apparent difference between mosquito groups, resulting from lower statistical power and greater noise, and could lead to false-positive results. In making infection comparisons between population groups, it is more accurate to compare the different groups after feeding simultaneously upon the same infective blood.

High Genetic Diversity of Plasmodium vivax on the North Coast of Papua New Guinea

Despite having the highest Plasmodium vivax burden in the world, molecular epidemiological data from Papua New Guinea (PNG) for this parasite remain limited. To investigate the molecular epidemiology of P. vivax in PNG, 574 isolates collected from four catchment sites in East Sepik (N = 1) and Madang (N = 3) Provinces were genotyped using the markers MS16 and msp1F3. Genetic diversity and prevalence of P. vivax was determined for all sites. Despite a P. vivax infection prevalence in the East Sepik (15%) catchments less than one-half the prevalence of the Madang catchments (27-35%), genetic diversity was similarly high in all populations (He = 0.77-0.98). High genetic diversity, despite a marked difference in infection prevalence, suggests a large reservoir of diversity in P. vivax populations of PNG. Significant reductions in transmission intensity may, therefore, be required to reduce the diversity of parasite populations in highly endemic countries such as PNG.

Prevalence of Mycobacterium avium subsp. paratuberculosis in farmed red deer (Cervus elaphus) with grossly normal mesenteric lymph nodes

AIM: To estimate the prevalence of Mycobacterium avium subsp. paratuberculosis (Map) in farmed deer with no gross post-mortem evidence of Map infection slaughtered in New Zealand, and to assess predictors of infection. METHODS: Mesenteric lymph node (MLN) samples (n = 251) were collected from 60 lines of deer presented at two slaughterhouses in the North and two in the South Island of New Zealand between October 2008 and January 2009 and cultured for Map. Estimates of individual animal prevalence for each island were adjusted to account for the clustering of individual observations within herds. The national herd prevalence estimate was calculated as a weighted mean, with weights being the proportion of herds from which deer were slaughtered at North and South Island slaughterhouses among all herds slaughtering deer throughout New Zealand. Age, gender, and the presence of other carcasses with enlarged and/or granulomatous MLN in the same line (line status) were assessed as predictors of infection using multivariable logistic regression. RESULTS: A national cluster-adjusted individual animal prevalence of 45 (95% CI = 30–60)% was estimated, with North and South Island prevalences of 29 (95% CI = 16–45)% and 51 (95% CI = 36–66)%, respectively. Line status was a strong predictor of infection in young deer (OR 7.1, 95% CI = 2.4–21.5), but not in older deer. Herd-level prevalence was 44 (95% CI = 24–64)% in the North Island and 67 (95% CI = 49–85)% in the South Island. Weighted adjustment resulted in a national herd-level prevalence estimate of 59 (95% CI = 41–78)%. CONCLUSIONS: This study has provided a national baseline prevalence estimate for Map infection at the individual and herd-level, showing a contrast between the North and South Islands. More research to investigate the factors contributing to the difference in infection prevalence seen between the islands may help to identify suitable control measures for Map in deer herds.

High levels of genetic diversity of Plasmodium falciparum populations in Papua New Guinea despite variable infection prevalence.

High levels of genetic diversity in Plasmodium falciparum populations are an obstacle to malaria control. Here, we investigate the relationship between local variation in malaria epidemiology and parasite genetic diversity in Papua New Guinea (PNG). Cross-sectional malaria surveys were performed in 14 villages spanning four distinct malaria-endemic areas on the north coast, including one area that was sampled during the dry season. High-resolution msp2 genotyping of 2,147 blood samples identified 761 P. falciparum infections containing a total of 1,392 clones whose genotypes were used to measure genetic diversity. Considerable variability in infection prevalence and mean multiplicity of infection was observed at all of the study sites, with the area sampled during the dry season showing particularly striking local variability. Genetic diversity was strongly associated with multiplicity of infection but not with infection prevalence. In highly endemic areas, differences in infection prevalence may not translate into a decrease in parasite population diversity.

Water Contact Activities and Prevalence of Schistosomiasis Infection among School-age Children in Communities along an Irrigation Scheme in Rural Northern Ghana

Of the various trematodes that infect humans, schistosomes remain among the most prevalent, and the various forms of schistosomiasis still pose significant public health problems. The prevalence of schistosomiasis infection among in-school and not-in-school children resident in communities along the Tono irrigation canals in northern Ghana was determined. Stool and urine samples from random representative samples were parasitologically examined using the Kato-Katz and 10 ml urine filtration methods respectively. A total of 920 children (mean age: 11.0 yrs; range: 6-15 yrs; STD Dev: 4.6 yrs), 573 (62.3%) males and 347 (37.7%) females with 473 in-school and 447 not-in-school participated in the study. The prevalence of Schistosoma haematobium infection was 33.2% (305/920) whilst that of S. mansoni was 19.8% (95% CI: 17.3-22.5; 182/920). The overall prevalence of infection (S. haematobium plus S. mansoni) was 47.7% (439/920). Many more males (51.7%; 95% CI: 47.5-55.8) than females (41.2%; 95% CI: 36.0-46.6) were infected. Forty-six (5.0%, 46/920) children were infected with both S. haematobium and S. mansoni. There was no difference in the prevalence of infection (S. haematobium plus S. mansoni) among children in-school (48.4%; 95% CI: 43.8-53.0) and those not-in-school (46.5%; 95% CI: 41.8-51.3). There was a statistically significant difference in prevalence of infection among communities (P=0.0002); with the lowest level of infection in residents of Korania (29.9%; CI: 20.0- 41.4) and the highest among those resident in Kajelo (64.9%; CI: 51.1-77.1), with significant differences in levels of water contact activities (χ2 =6.69; P=0.04). The highest intensity of S. mansoni infection (115.6 epg) was in Bonia where the highest prevalence of blood stained stools was collected (5.5%). Overall, 2.8% (26/920; 95% CI: 1.9-4.2) of stool samples were blood stained, whilst 10% (92/920; 95% CI: 8.2-12.2) of children had haematuria. S. haematobium ova were detected in 98.9% (91/92) of blood stained urine samples. Children infected by S. mansoni were more likely to have blood stained stool (χ2 =32.7; P<0.0001). The prevalence of schistosomiasis infection in the irrigation project site is high, adding praziquantel to albendazole and ivermectin for distribution during the annual mass drug administration for filariasis and onchocerciasis control will be an effective way of reaching all at risk groups in the Kassena-Nankana district for the control of schistosomiasis.

Relative geographic range of sibling species of host damselflies does not reliably predict differential parasitism by water mites

BackgroundOne of the main challenges in evolutionary parasitology is to determine the factors that explain variation among host species in parasitism. In this study, we addressed whether host phylogeny or ecology was important in determining host species use by water mites. Parasitism (prevalence and intensity) by Arrenurus water mites was examined in relation to geographic distribution of host damselflies from sibling species pairs. In addition, the likelihood of putative mite species parasitizing both species of a host species pair was explored.ResultsA total of 1162 damselflies were examined for water mites across four sites in Southeastern Ontario. These damselflies represent ten species (five closely related host species pairs) in the Coenagrionidae. Only two of the five species pairs showed near significant or significant differences in prevalence of infection by mites. In one of those species comparisons, it was the less widespread host that had higher water mite prevalence and in the other species comparison, the less widespread host species had lower water mite prevalence. Only one of the five pairs showed a significant difference in intensity of infection; intensity was higher in the species with a smaller geographic distribution. Based on the COI barcode, there were nine water mite clades (OTU) infecting these ten host species. Three Arrenurus OTUs may be host monospecific, four OTUs were specific to a given host species pair, and two OTUs infected at least three host species. Host species in each species pairs tend to share at least one of the Arrenurus OTU. No striking differences in mite species diversity were found among species in any species pair. Finally, the Arrenurus examined in this study appear to be ecological specialists, restricted to a particular type of habitat, parasitizing few to many of the host species present in that site or habitat.ConclusionsAlthough differences in levels of parasitism by water mites exist for some closely related hosts species, no such differences were found between other related host species. Differences in geographic range of related host species does not reliably explain differential levels of parasitism by water mites.

HIV-, HCV-, HBV- und Syphilissurveillance unter Blutspendern in Deutschland 2008–2010

The Robert Koch Institute collects and evaluates data on the prevalence and incidence of HIV, hepatitis C (HCV), hepatitis B (HBV) and syphilis infections among blood and plasma donors in Germany according to article 22 of the Transfusion Act. This report includes data from all blood donation services in Germany for 2008-2010. The prevalence for HIV ranged from 6.6-7.0/100,000, for HCV from 68.9-81.6/100,000, for HBV from 116.2-136.6/100,000 and for syphilis from 31.0-42.1/100,000 donations. The proportion of incident infections per 100,000 donations ranged from 0.8-0.9 for HIV, 0.8-1.0 for HCV, 0.3-0.5 for HBV and 1.4-1.6 for syphilis. Since 2001 the prevalence and incidence of HBV and HCV among blood has declined whereas incident HIV infections reached a peak in 2008 and 2010 and show an increasing trend. Also, the proportion of syphilis infections among first time donors was highest in 2010. Significant differences in infection prevalence and incidence were found between the sexes, different age groups and different donation types. In order to optimise donor selection a validated donor questionnaire should be used and confidentiality in all steps of donation should be assured. The possibility of a confidential self-exclusion should be explicitly pointed out to donors.

PREVALENCE OF INFECTION BY BATRACHOCHYTRIUM DENDROBATIDIS AND RANAVIRUS IN EASTERN HELLBENDERS (CRYPTOBRANCHUS ALLEGANIENSIS ALLEGANIENSIS) IN EASTERN TENNESSEE

Hellbenders (n=97) were collected from the Little and Hiwassee Rivers in eastern Tennessee, USA, during 2009 and 2010. Location and morphometrics for each animal were recorded, and nonlethal tissue samples were collected to estimate the prevalence of infection with Batrachochytrium dendrobatidis (Bd) and Ranavirus in each watershed and year. Real-time polymerase chain reaction was performed on skin swabs for Bd and on tail clips for ranaviruses. Overall prevalences of DNA of Bd, Ranavirus, and coinfections (i.e., detectable DNA of both pathogens in the same individual) were 26%, 19%, and 5%, respectively. Differences in infection prevalence were detected between watersheds and years. Gross lesions were observed in 31 animals (32%), but the types of lesions were not consistent with chytridiomycosis or ranaviral disease. This is the first report of infection of eastern hellbenders with Bd and Ranavirus. Despite infection by both pathogens, it is unclear whether chytridiomycosis or ranaviral disease develops in wild populations of hellbenders. More research is needed to determine the susceptibility of hellbenders to Bd and ranaviruses and their role in the epidemiology of these pathogens.

Local haemoparasites in introduced wetland passerines

When colonizing a new area, introduced species may lose their original haemoparasites. If the local parasites are unable to infect the novel introduced hosts, these may gain a fitness advantage over their local competitors. Alternatively, the introduced species may be susceptible to local parasites and enter the local transmission dynamics. We studied these two possibilities in communities of wetland passerines infected with haemosporidians (genera Haemoproteus and Plasmodium) in Portugal, southwest Europe. Four introduced and six native (resident and breeding migrant) passerine species were tested for haemosporidians in four reed beds. Our results suggest that the introduced species have lost their original haemoparasites upon colonization and entered the local transmission cycle. Two local Plasmodium lineages infected the exotic species: one of them (SGS1) was the most host generalist and prevalent lineage in the native species, so was expected to be present in the exotics at random. The other lineage (PADOM01) was rarer in the sampled community, but was present in native hosts that are phylogenetically close to the infected exotic species; therefore, the colonization of the exotic host by PADOM01 seems to be constrained by the parasite’s specialization and by phylogenetic factors. When phylogeny was controlled for, there were no significant differences in infection prevalence and number of lineages between exotics and natives.

Temporal Variation in Infection Prevalence by the Amphibian Chytrid Fungus in Three Species of Frogs at La Selva, Costa Rica

AbstractThe emerging infectious disease chytridiomycosis, caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in widespread population declines, extirpations, and extinctions of amphibians throughout the world. In the Neotropics, most amphibian declines have occurred in cool mid‐ to high‐elevation sites (&gt; 400 m asl), and it is hypothesized that high temperatures limit the growth of Bd in lowland tropical sites, despite few data available on the distribution of Bd in lowland forests. Here, we report the results of a 12‐mo pathogen surveillance program for three common species of frogs at a warm lowland site in northeastern Costa Rica. We combine standard non‐invasive skin swabbing techniques with a quantitative polymerase chain reaction assay to analyze the infection prevalence and Bd load across a 1‐yr period. Our data indicate an overall Bd infection rate of 6.1 percent, but prevalence varies from &lt; 5 percent in warmer months to a peak of 34.7 percent in the coolest months of the year. Despite very little seasonal variation in temperature (&lt; 4°C), our data indicate strong seasonal variation in the prevalence of Bd, with highest prevalence of infection in months with coolest air temperatures. While it has been suggested that Bd is primarily a riparian fungus, we find no difference in prevalence of infection among our species despite considerable differences in affiliation of these species with water. Our study provides further evidence that infection by Bd is regulated by temperature and shows that warm temperatures in lowland forests may restrict, but not prevent, infection by Bd.

A mathematical epidemiological model of gram-negative Bartonella bacteria: does differential ectoparasite load fully explain the differences in infection prevalence of Rattus rattus and Rattus norvegicus?

We postulate that the large difference in infection prevalence, 24% versus 5%, in R. norvegicus and R. rattus, respectively, between these two co-occurring host species may be due to differences in ectoparasite and potential vector infestation rates. A compartmental model, representative of an infectious system containing these two Rattus species and two ectoparasite vectors, was constructed and the coefficients of the forces of infection determined mathematically. The maximum difference obtained by the model in the prevalence of Bartonella in the two Rattus species amounts to 4.6%, compared to the observed mean difference of 19%. Results suggest the observed higher Bartonella infection prevalence in Rattus norvegicus compared to Rattus rattus, cannot be explained solely by higher ectoparasite load. The model also highlights the need for more detailed biological research on Bartonella infections in Rattus and the importance of the flea vector in the spread of this disease.