Homozygosity of adenylate kinase allele 3: Two cases

Summary The phenotype AK 3.3 in the isoenzyme system of human adenylate kinase has been found in two members of the Wayampi population of French Guiana.     

A genetic study of two French Guiana Amerindian populations

Two Amerindian populations of French Guiana were investigated for plasma proteins and red-cell enzymes. In the Wayampi tribe, rare variants were identified in 4 systems. The corresponding alleles are designated AK1 3 Wayampi, PGM1 (4/10) Wayampi, PGM2 6 Wayampi, and TfD. In the Emerillon tribe, a variant allele of PGM2, designated PGM2 6 Emerillon, was identified. For three of the systems, PGM1, PGM2, Tf, similar isozymes have been described in other Amerindian populations. These findings suggest that the corresponding alleles may have the same origin.     

Malnutrition and its association with intestinal parasitism among children from a village in the Colombian Amazonian region

Intestinal parasites and malnutrition cause high morbidity among children in developing countries. A study to establish the associations between intestinal parasitism and undernourishment was undertaken in a village in the Colombian Amazon region. Two hundred thirty seven children each provided four stool samples for parasitic analysis. Anthropometric indices were calculated based on height and weight (HAZ), weight and age (WAZ) and height and weight (WHZ) using the international growth standards recommended by the World Health Organization. Of the 237 children, 86.1% were carrying parasites, 54% had 2 or more parasites, 30% were stunted, 10% were underweight, and 2.5% were wasting. HAZ and WAZ indices were inversely related to age and number of parasites. Socioeconomic status was positively correlated with the number of parasites and inversely related to the HAZ index (p < 0.05). In conclusion, frequencies of undernourishment and intestinal parasites among the sample population were higher than the national average for Colombia. As previous studies have indicated, age, intestinal parasitism and socio-economic level are variables significantly related to nutritional state.     

Characteristics of human intestinal Escherichia coli with changing environments

To investigate if the characteristics of human intestinal Escherichia coli are changing with the environment of the host, we studied intestinal E. coli from subjects having recently migrated from a temperate to a tropical area. We determined the phylogenetic group, the prevalence of the antibiotic resistance, the presence of integrons and the strain diversity in faecal isolates from 25 subjects originally from metropolitan France and expatriated to French Guyana. These characteristics were compared with those of 25 previously studied Wayampi Amerindian natives of French Guyana and from 25 metropolitan French residents. The three groups of subjects were matched for age and sex, had not taken antibiotics for at least 1 month, nor had been hospitalized within the past year. In all, the characteristics of intestinal E. coli from Expatriates were intermediate between those found in residents from metropolitan France and those found in natives of French Guyana. Prevalence of carriage of resistant Gram-negative bacteria in Expatriates was intermediate between French residents and Wayampi as were the prevalence of integrons in E. coli (12.3% versus 16.3% and 7.8% respectively), and the intra-host diversity of E. coli (2.3 strains/subject versus 1.9 and 3.1, respectively); lastly, in Expatriates, the prevalence of carriage of phylogenetic group B2 strains was lower than in French residents (16% versus 56%, P  = 0.005), while carriage of phylogenetic group A strains was lower than in Wayampi (56% versus 88%, P  = 0.03). Our results suggest that the composition of the commensal intestinal flora of humans is not static but changes dynamically in response to new environmental conditions.     

Ecology and biology ofNoctuidonema guyanense (Nematoda,aphelenchoididae), an ectoparasite ofSpodoptera frugiperda (Lep., Noctuidae), in French Guiana

Male and female moths ofSpodoptera frugiperda (J. E. Smith), collected in French Guiana between 1980 and 1987 were examined to evaluate the level of parasitism by the Aphelenchoidid ectoparasitic nematodeNoctuidonema guyanense Remillet &; Silvain. The rate of parasitism varies according to the population level ofS. frugiperda, the sex of the moths, number of matings, and age of the females. The results confirm that the transmission of the nematode from one moth to another occurs during mating. The growth of a nematode colony on a moth seems to be limited by the development of the physiological state of the host.     

Condition-dependent expression of virulence in a trypanosome infecting bumblebees

Parasite virulence affects both the temporal dynamics of host-parasite relationships and the degree to which parasites regulate host populations. If hosts can compensate for parasitism, then parasites may exhibit condition-dependent virulence, with high virulence being seen only when the host is under conditions of stress. Despite their usually low level of virulence, theory suggests that such parasites may still affect host population dynamics. We tested whether a trypanosome intestinal parasite of bumblebees, Crithidia bombi , expresses condition-dependent virulence. Hosts were infected with the parasite and then kept under either favourable or starvation (stressed) conditions. Under favourable conditions the infection caused no mortality, while when hosts were starved the infection increased the host mortality rate by 50%. In addition, we found a parasite-related change in host resource allocation patterns. Infected bees invested relatively more resources into their fat body and less into their reproductive system than did non-infected bees. Whether this reallocation is parasite-driven, to enhance transmission, or a host-response to parasitism, remains unknown.     

Parasite mediated mortality and host immune response explain age-related differences in blood parasitism in birds

An important pattern in host-parasite assemblages is a higher intensity of parasites in juveniles than in adults, but the reasons for these differences remain obscure. Three non-mutually exclusive hypotheses have been proposed: (1) heavily parasitized juveniles die before being recruited into the adult population ('selection' hypothesis); (2) the development of an acquired immunity by the host in front of the parasite reduces the intensity of the parasite in adult hosts ('immunity' hypothesis); and (3) differences in behavior makes adults less exposed to the parasite than juveniles ('vector exposure' hypothesis). Having rejected the 'vector exposure' hypothesis in a previous study, here we tested the 'selection' and 'immunity' hypotheses in feral pigeons (Columba livia) infected by the blood parasite Haemoproteus columbae. In agreement with the 'selection' hypothesis, young (but not adult) pigeons that were highly parasitized had a lower probability of surviving until adulthood, independent of their body condition. However, selection was not strong enough to account for the observed differences in parasite intensity between age-classes, and after selection parasite intensity of survivors still remained 85% higher in juveniles than in adults. In contrast, the 'immunity' hypothesis offered a greater explanatory power. The intensity of blood parasites in young pigeons, but not in adults, decreased over time so dramatically that by the time they had become adults their intensities were indistinguishable from that typically seen in adults. Therefore, while selection against highly parasitized juveniles can contribute to some extent to a reduction in parasitism seen in the adult population, age-specific blood parasitism in feral pigeons is best explained as a transitory phase just before the host develops an effective immune response.     

Intestinal parasites in southeast Asian refugees two years after immigration.

We collected stool specimens from 2,520 Southeast Asian refugees who had resided in the United States for an average of 2.1 years. More than half reported receiving prior treatment of parasites. At least one parasite was discovered in 32%, and multiple parasites were found in 8% of patients. Hookworm, Giardia, Strongyloides, and Hymenolepis nana were most commonly found. In comparison to studies done at the time of immigration, all parasites had decreased in frequency, but Giardia, hookworm, and H nana remain common. Although initial screening efforts may have failed to identify substantial numbers of infected refugees, poor compliance with treatment may also explain the persistence of intestinal parasites in our patients. The continued presence of Giardia and H nana, especially among children, may be explained by person-to-person transmission or autoinfection.     

Reproductive strategies and population structure in Leishmania: substantial amount of sex in Leishmania Viannia guyanensis

Leishmania species of the subgenus Viannia and especially Leishmania Viannia guyanensis are responsible for a large proportion of New World leishmaniasis cases. Since a recent publication on Leishmania Viannia braziliensis, the debate on the mode of reproduction of Leishmania parasites has been reopened. A predominant endogamic reproductive mode (mating with relatives), together with strong Wahlund effects (sampling of strains from heterogeneous subpopulations), was indeed evidenced. To determine whether this hypothesis can be generalized to other Leishmania Viannia species, we performed a population genetic study on 153 human strains of L. (V.) guyanensis from French Guiana based on 12 microsatellite loci. The results revealed important homozygosity and very modest linkage disequilibrium, which is in agreement with a high level of sexual recombination and substantial endogamy. These results also revealed a significant isolation by distance with relatively small neighbourhoods and hence substantial viscosity of Leishmania populations in French Guiana. These results are of epidemiological relevance and suggest a major role for natural hosts and/or vectors in parasite strain diffusion across the country as compared to human hosts.     

Population density and phenotypic attributes influence the level of nematode parasitism in roe deer

The impact of parasites on population dynamics is well documented, but less is known on how host population density affects parasite spread. This relationship is difficult to assess because of confounding effects of social structure, population density, and environmental conditions that lead to biased among-population comparisons. Here, we analyzed the infestation by two groups of nematodes (gastro-intestinal (GI) strongyles and Trichuris) in the roe deer (Capreolus capreolus) population of Trois Fontaines (France) between 1997 and 2007. During this period, we experimentally manipulated population density through changes in removals. Using measures collected on 297 individuals, we quantified the impact of density on parasite spread after taking into account possible influences of date, age, sex, body mass, and weather conditions. The prevalence and abundance of eggs of both parasites in females were positively related to roe deer density, except Trichuris in adult females. We also found a negative relationship between parasitism and body mass, and strong age and sex-dependent patterns of parasitism. Prime-age adults were less often parasitized and had lower fecal egg counts than fawns or old individuals, and males were more heavily and more often infected than females. Trichuris parasites were not affected by weather, whereas GI strongyles were less present after dry and hot summers. In the range of observed densities, the observed effect of density likely involves a variation of the exposure rate, as opposed to variation in host susceptibility.     

Status of intestinal parasite infections among children in Bat Dambang, Cambodia

A survey was conducted to determine the extent of intestinal parasite infection in Bat Dambang, Cambodia in March 2004. A total of 623 fecal specimens was collected from kindergarten and schoolchildren and examined using the formalin-ether sedimentation technique. The overall infection rate of intestinal parasites was 25.7% (boys, 26.2%; girls, 25.1%), and the infection rates of intestinal helminthes by species were as follows: Echinostoma sp. 4.8%, hookworm 3.4%, Hymenolepis nana 1.3%, and Rhabditis sp. 1.3%. The infection rates of intestinal protozoa were; Entamoeba coli 4.8%, Giardia lamblia 2.9%, Iodamoeba butschlii 1.4%, Entamoeba polecki 1.1%, and Entamoeba histolytica 0.8%. There were no egg positive cases of Ascaris lumbricoides or Trichuris trichiura. All children infected were treated with albendazole, praziquantel, or metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in Bat Dambang, Cambodia.     

Significant difference of temperature-dependent sex determination between French Guiana (Atlantic) and Playa Grande (Costa-Rica,Pacific) leatherbacks (Dermochelys coriacea)

Temperature-dependent sex determination has been recently characterized for leatherbacks (Dermochelys coriacea) from Playa Grande, on the Pacific coast of Costa Rica. The authors concluded that the pattern of TSD in leatherbacks from Pacific Costal Rica is the same as for leatherbacks from French Guiana, in the Atlantic. However, no statistical tests were performed to validate their conclusion. Here, we use a maximum-likelihood test to look for a possible difference between the populations. We found that the pattern of temperature-dependent sex determination in Atlantic and Pacific leatherbacks was significantly different. The temperature producing 50 % of each sex was not significantly different in both groups, but the range of temperatures producing both sexes was significantly narrower for the French Guiana population. We hypothesize that this difference could reflect a lower genetic polymorphism for temperature-dependent sex determination in this population. A low genetic diversity in the Guiana population compared to the Playa Grande population has been already observed for mitochondrial haplotypes. Our results emphasize the importance of statistical analyses in studies of temperaturedependent sex determination.     

Genetic studies in French Guiana populations: Synthesis

Twelve blood group and protein systems from a total of 819 individuals from six tribal groups (Apalaí‐Wayana, Emerillon, Kaliña, Palikur Wayampi, and Wayana) living in French Guiana and Brazil were compared with each other and integrated with previous results from 17 other South Amerindian populations studied for the same genetic markers. Using correspondence analysis, map methodologies, and maximum linkage cluster analysis developed with the UPGMA method, we attempted to establish the genetic position of these tribes among South American Indians. Peripheral positions for the Emerillon and the Palikur were observed. Ethnohistorical data in French Guiana suggest that a strong founder effect for the former and endogamy for the latter could have generated the genetic differentiation of these two ethnic groups. However, when considered in a wider context, all French Guiana Natives cluster together in an intermediate position as compared with 17 other Amerindian groups studied for the comparison. Am J Phys Anthropol, 2007. © 2006 Wiley‐Liss, Inc.     

Male-biased parasitism by common helminths is not explained by sex differences in body size or spleen mass of breeding cormorants Phalacrocorax auritus

In vertebrates, males are often more parasitised than conspecific females. This bias in parasitism might result from sex differences in parasite exposure and/or susceptibility to infection. Such information is important for testing hypotheses about allocation of resources to life histories of males and females and for testing hypotheses about factors thought to influence parasite fitness and parasite dynamics. We tested whether double-crested cormorants Phalacrocorax auritus exhibit male-biased parasitism by gut helminths. The prevalence of nematode Contracaecum spp. and trematode Drepanocaphalus spathans infections was ∼90% and 39%, respectively. Cestode, primarily Paradilepis caballeroi and acanthocephalan Andracantha gravida infections were less common (<10%). Male and female cormorants did not differ in prevalence of infection by any helminth species. However, males had twice the abundance and intensity of Contracaecum spp. infections and twice the intensity of D. spathans infections than found in females. For common parasites showing male-biased parasitism, degree of parasitism was also unrelated to body size or mass in either sex. Males and females did not differ in spleen mass and spleen mass was unrelated to abundance of common parasites. Furthermore, abundance of trematodes and nematodes was not correlated. At present, male biases in parasitism by nematodes and trematodes in cormorants are independent patterns that remain unexplained, but are most likely attributable to sex differences in exposure and/or immunological differences not yet assessed.     

Anthropogenic impacts on Costa Rican bat parasitism are sex specific

While anthropogenic impacts on parasitism of wildlife are receiving growing attention, whether these impacts vary in a sex‐specific manner remains little explored. Differences between the sexes in the effect of parasites, linked to anthropogenic activity, could lead to uneven sex ratios and higher population endangerment. We sampled 1108 individual bats in 18 different sites across an agricultural mosaic landscape in southern Costa Rica to investigate the relationships between anthropogenic impacts (deforestation and reductions in host species richness) and bat fly ectoparasitism of 35 species of Neotropical bats. Although female and male bat assemblages were similar across the deforestation gradient, bat fly assemblages tracked their hosts closely only on female bats. We found that in female hosts, parasite abundance per bat decreased with increasing bat species richness, while in male hosts, parasite abundance increased. We hypothesize the differences in the parasite–disturbance relationship are due to differences in roosting behavior between the sexes. We report a sex‐specific parasite–disturbance relationship and argue that sex differences in anthropogenic impacts on wildlife parasitism could impact long‐term population health and survival.     

Prevalence of intestinal parasitic infections among inhabitants of Tan-nan village, Nantou County, Taiwan.

The pork infected with cysticerci was sent to our laboratory in June 1971. Microscopic examination revealed the infection of Cysticercus cellulosae. Subsequently, the source of the pork was traced, and the survey of intestinal parasitism was carried out among inhabitants at Tan-nan village, Hsin-I District, Nantou County, Taiwan, in August 1973. Results obtained only indicated the presence rather than endemic of taeniasis solium in this village. The parasites and infection rates found in the present study from 417 individuals by means of direct smear and formalin-ether sedimentation technic of stool specimens are as follows: Ascaris lumbricoides (81.3%), hookworm (30.9%), Trichuris trichiura (73.6%), Strongyloides stercoralis (0.5%), Clonorchis sinensis (2.9%), Hymenolepis diminuta (0.7%), Taenia solium (0.2%), Taenia saginata (0.2%), Entamoeba histolytica (3.1%), Entamoeba coli (8.4%), Endolimax nana (2.6%), and Giardia lamblia (4.3%).     

一种叶甲(Timarcha maritima)(鞘翅目:叶甲科)的种群变异性

本文研究了一种叶甲(Timarchamaritima)的种群变异性,在此物种的整个分布范围内,沿法国大西洋海岸取选10个种群,测定个体大小、生育力、寄生量、性比、交配模式几个变量,各变量在不同种群间呈现显著差异。我们的调查结果也表明:原生生物(簇虫,Gregarinamunieri)的寄生是影响T.maritima生态习性的主要因素;这种甲虫的交配模式与寄生量有关,这种交配模式3年前已在一个高寄生种群内发现;个体大小与交配的关联不显著,即便是在没有寄生的种群中也是这样;在不同种群间,寄生感染程度也是一个有力的指示量,可以预示雌性个体的生育力变化;相反,不管观察什么种群,外寄生种(蜱螨,Pseudamansiachrysomelinus)(Acari:Canestriniidae)的作用很小。这项研究表明:在研究种群生态学时,需要同时观察寄生物的影响。     

Hymenolepis nana: intestinal tissue phase in actively immunized mice.

We investigated the fate of the intestinal cestode Hymenolepis nana in immunized mice. Immunity was induced by infection with the parasite eggs. These immunized animals and unimmunized controls were then challenged with 50,000 H. nana eggs. The mice were killed 4 to 90 hr after challenge, and H. nana in the intestinal tissue were counted. At 4 hr after challenge the unimmunized and immunized animals had approximately equal numbers of oncospheres. By 12 hr there were fewer parasites in the immunized than in the unimmunized animals. At 90 hr, no H. nana were seen in the immunized mice, whereas in the unimmunized animals the median number of cysticercoids was more than 1,000. It appears, therefore, that in mice well immunized to H. nana by infection, challenge oncospheres can burrow into the intestinal tissue before they are killed. The reduced number of oncospheres in the immunized mice 12 hr after challenge, and the accumulation of eosinophils near individual oncospheres still present, indicate that an immune response to the parasite was taking place. Absence of a lymphocyte infiltration near any of the oncospheres suggests that the mechanism of immunity was not lymphocyte mediated; thus, the histopathology of the reaction is consistent with that of humoral immunity.     

First identification of eggs of the Asian fish tapeworm Bothriocephalus acheilognathi (Cestoda: Bothriocephalidea) in human stool

We report the first case of egg isolation of the Asian fish tapeworm Bothriocephalus acheilognathi (Bothriocephalidea) from human stool. A male patient from Saint Laurent du Maroni (French Guiana) presenting abdominal pain was examined in France for the diagnosis of intestinal parasites. Diphyllobothrium-like eggs were observed in his stool. However, molecular phylogenetic analyses based on sequences of rDNA and COI genes showed that the eggs observed belong to a bothriocephalidean cestode B. acheilognathi. The adult life stages of B. acheilognathi cestodes are known as invasive parasites of a wide spectrum of fish; however, they have not been described to parasitize any mammals. This human infection seems to be accidental and represents a parasite passage through human intestine after the consumption of an infected fish host.     

The evolution of brood parasitism: the role of facultative parasitism

The hypothesis that facultative brood parasitism may serve asan intermediate step in the evolutionary transition from purelyparental reproduction to obligate parasitism was investigated.The population dynamics of a host-parasite complex were computer-simulatedin a model that incorporated different intensities of parasitismand host defense and considered a simplified semelparous birdspecies living in a homogeneous habitat The individuals usetwo different breeding strategies: provide parental care orparasitize the nest of those providing parental care. Underobligate parasitism, the parasites appeared unsuccessful, drovethe host population to extinction, or coexisted with the hostin stable or oscillating proportions. The behavior of the systemdepended on both the effectiveness of the parasite and the defenseof the host. Under facultative parasitism (making the best ofa bad job), the parasites reduced host numbers but did not reducethe population size below the number of breeding sites. Thus,facultative parasitism provides a better opportunity for thedevelopment of defense in the host. The population of a hostthat shows a certain level of defense can be more successfullyinvaded by obligate parasites so that stable coexistence ofhosts and parasites is possible.