Dry areas: an example of seasonal evolution of helminth infection of sheep and goats in southern Mauritania

Characterization of virulence determinants and phylogenetic background of multiple and extensively drug resistant Escherichia coli isolated from different clinical sources in Egypt

Abstract

Escherichia coli is a multifaceted microbe since some are commensals, normally inhabiting the gut of both humans and animals while others are pathogenic responsible for a wide range of intestinal and extra-intestinal infections. It is one of the leading causes of septicemia, neonatal meningitis, urinary tract infections (UTIs), cystitis, pyelonephritis, and traveler’s diarrhea. The present study aims to survey the distribution and unravel the association of phylotypes, virulence determinants, and antimicrobial resistance of E. coli isolated from different clinical sources in Mansoura hospitals, Egypt. One hundred and fifty E. coli isolates were collected from different clinical sources. Antimicrobial resistance profile, virulence determinants, and virulence encoding genes were detected. Moreover, phylogenetic and molecular typing using ERIC-PCR analysis was performed. Our results have revealed that phylogroup B2 (26.67%) with the greatest content in virulence traits was the most prevalent phylogenetic group. Different virulence profiles and varying incidence of virulence determinants were detected among tested isolates. High rates of resistance to different categories of antimicrobial agents, dramatic increase of MDR (92.67%), and emergence of XDR (4%) were detected. ERIC-PCR analysis revealed great diversity among tested isolates. There was no clustering of isolates according to resistance, virulence patterns, or phylotypes. Our research has demonstrated significant phylogenetic diversity of E. coli isolated from different clinical sources in Mansoura hospitals, Dakahlia governorate, Egypt. E. coli isolates are equipped with various virulence factors which contribute to their pathogenesis in human. The elevated rates of antimicrobial resistance and emergence of MDR and XDR mirror the trend detected globally in recent years.

Key points

• Clinical E. coli isolates exhibited substantial molecular and phylogenetic diversity.

• Elevated rates of antimicrobial resistance and emergence of XDR in pathogenic E. coli.

• B2 Phylogroup with the highest VS was the most prevalent among pathogenic E. coli.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-021-11740-x.

Rainfall as a driver of seasonality in parasitism

Parasite burdens are known to vary seasonally in wildlife, and rainfall is one key aspect of seasonality that has been linked to parasitism in a range of systems. Rainfall can have immediate effects on parasitism rates by affecting parasite survival and movement in the environment, or it can have delayed effects by affecting host susceptibility to parasites through changes in host body condition or immune function. In this study, we examined how helminth infection in a wild ungulate (Grant's gazelle, Nanger granti) is impacted by seasonal changes in rainfall. We looked at how the burdens of three helminth parasites varied in relation to current (immediate effect) and prior (delayed effect) rainfall by comparing parasite fecal egg and larval counts to rainfall 0, 1, and 2 months prior to parasite sampling. We found burdens of all three parasites to be negatively associated with rainfall, and that delayed effects were stronger than immediate effects. Our findings implicate rainfall as a driver of seasonal variation in infection and suggest one important mechanism may be through delayed effects on host susceptibility.

Effect of non-genetic factors on the prevalence of Stilesia globipunctata in the goat

Despite its high prevalence and pathogenicity, Stilesia globipunctata is a neglected cestode infection of ruminants in the tropics and sub-tropics. The present study reports the effect of sex, age, year and month on the prevalence of S. globipunctata in the goat. A total of 5208 eviscerated intestines of the goat carcasses were screened for a period of seven years, from January 2001 to December 2007. The overall prevalence of 36.6 % was significantly affected by the factors studied (P<0.05). Male goats were more susceptible to the S. globipunctata infection than that of female (P<0.05). Goat aged between 6 months and 1 year were found to be significantly more susceptible (P<0.05) which was followed by animals between 1 and 4 years of age and then more than 4 years of age. Morbidity was high (59 to 86 %) in animals of less than one year of age. The striking observation was that the prevalence peaked during monsoon and at nadir in May.

Gastrointestinal helminths may affect host susceptibility to anthrax through seasonal immune trade-offs

Background

Most vertebrates experience coinfections, and many pathogen-pathogen interactions occur indirectly through the host immune system. These interactions are particularly strong in mixed micro-macroparasite infections because of immunomodulatory effects of helminth parasites. While these trade-offs have been examined extensively in laboratory animals, few studies have examined them in natural systems. Additionally, many wildlife pathogens fluctuate seasonally, at least partly due to seasonal host immune changes. We therefore examined seasonality of immune resource allocation, pathogen abundance and exposure, and interactions between infections and immunity in plains zebra (Equus quagga) in Etosha National Park (ENP), Namibia, a system with strongly seasonal patterns of gastrointestinal (GI) helminth infection intensity and concurrent anthrax outbreaks. Both pathogens are environmentally transmitted, and helminth seasonality is driven by environmental pressures on free living life stages. The reasons behind anthrax seasonality are currently not understood, though anthrax is less likely directly driven by environmental factors.

Results

We measured a complex, interacting set of variables and found evidence that GI helminth infection intensities, eosinophil counts, IgE and IgGb antibody titers, and possibly IL-4 cytokine signaling were increased in wetter seasons, and that ectoparasite infestations and possibly IFN-γ cytokine signaling were increased in drier seasons. Monocyte counts and anti-anthrax antibody titers were negatively associated with wet season eosinophilia, and monocytes were negatively correlated with IgGb and IgE titers. Taken together, this supports the hypothesis that ENP wet seasons are characterized by immune resource allocation toward Th-2 type responses, while Th1-type immunity may prevail in drier seasons, and that hosts may experience Th1-Th2 trade-offs. We found evidence that this Th2-type resource allocation is likely driven by GI parasite infections, and that these trade-offs may render hosts less capable of concurrently mounting effective Th1-type immune responses against anthrax.

Conclusions

This study is one of the first to examine laboratory-demonstrated Th1-Th2 trade-offs in a natural system. It provides evidence that seasonally bound pathogens may affect, through immunology, transmission dynamics of pathogens that might otherwise not be seasonally distributed. It suggests that, by manipulating the internal host ecosystem, GI parasites may influence the external ecosystem by affecting the dynamics of another environmentally transmitted pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/s12898-014-0027-3) contains supplementary material, which is available to authorized users.

Sequence variation in two mitochondrial DNA regions and internal transcribed spacer among isolates of the nematode Oesophagostomum asperum originating from goats in Hunan Province, China

The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5–72% for pcox1, 73.7–74.2% for pnad1 and 58–58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0–1.6% for pcox1, 0–1.9% for pnad1 and 0–1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1–12.5%, 13.3–17.7% and 8.5–18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum.

Seasonal and demographic factors influencing gastrointestinal parasitism in ungulates of Etosha National Park

Host-parasite dynamics can be strongly affected by seasonality and age-related host immune responses. We investigated how observed variation in the prevalence and intensity of parasite egg or oocyst shedding in four co-occurring ungulate species may reflect underlying seasonal variation in transmission and host immunity. This study was conducted July 2005-October 2006 in Etosha National Park, Namibia, using indices of parasitism recorded from 1,022 fecal samples collected from plains zebra (Equus quagga), springbok (Antidorcas marsupialis), blue wildebeest (Connochaetes taurinus), and gemsbok (Oryx gazella). The presence and intensity of strongyle nematodes, Strongyloides spp. and Eimeria spp. parasites, were strongly seasonal for most host-parasite combinations, with more hosts infected in the wet season than the dry season. Strongyle intensity in zebra was significantly lower in juveniles than adults, and in springbok hosts, Eimeria spp. intensity was significantly greater in juveniles than adults. These results provide evidence that acquired immunity is less protective against strongyle nematodes than Eimeria spp. infections. The seasonal patterns in parasitism further indicate that the long dry season may limit development and survival of parasite stages in the environment and, as a result, host contact and parasite transmission.

Fatal gastrointestinal parasitism in goats: 31 cases (2001-2006)

OBJECTIVE

To evaluate signalment, history, clinical and pathologic findings, and seasonal weather patterns in association with fatal gastrointestinal parasitism in goats.

DESIGN

Retrospective case series.

ANIMALS

152 goats that were > 1 day of age.

PROCEDURES

Characteristics including age and counts of coccidia oocysts and trichostrongyle ova (eggs) per gram of feces (EPG) in goats that died because of gastrointestinal parasitism and goats that died because of other causes were compared. Weather data and annual incidence of caprine fatal gastrointestinal parasitism were investigated.

RESULTS

Death was attributed to gastrointestinal parasitism in 31 of 152 (20%) goats (median age, 5 months; range, 1 month to 7 years); deaths were attributed to coccidiosis (n = 7 goats; median age, 4 months; median EPG, 2,225), trichostrongylosis (6 goats; median age, 1.25 years; median EPG, 3,700), or dual infection (18 goats; median age, 6.7 months; median EPG, 8,088 coccidia and 5,475 trichostrongyles). Sudden onset of weakness or death was a common historical finding; diarrhea was evident in 15 goats. Common postmortem findings in these goats included cachexia, tissue pallor, poorly formed feces, and mesenteric lymphadenomegaly. Wet weather in spring and summer was associated with increased annual incidence of fatal gastrointestinal parasitism in goats.

CONCLUSIONS AND CLINICAL RELEVANCE

Gastrointestinal parasitism is an important cause of death in goats. Clinical signs may not develop until just prior to death, and diagnosis is achieved via parasitologic evaluation of feces and necropsy. Seasonal weather patterns should be considered on an annual basis when designing parasite control programs for goats.

Point prevalence of gastrointestinal helminthiasis in ruminants in southern Punjab, Pakistan

The present study was carried out to determine the prevalence of gastrointestinal helminthiasis in ruminants in an irrigated area of lower Punjab (Pakistan). For this purpose, 100 faecal samples were collected from sheep, goats, cattle and buffaloes. Parasitological procedures including direct and indirect methods (sedimentation and floatation) and coproculture were used for the identification of helminths. The overall prevalence of helminthiasis was 51% in cattle, 47% in buffaloes, 62% in sheep and 52% in goats, with nematodes being the most common helminths. The prevalence of helminths was higher in young animals compared with adults in cattle (P < 0.0001), buffaloes (P < 0.0001), sheep (P < 0.059) and goats (P = 0.010). The prevalence of different species of helminths also varied in different age groups, with Toxocara vitulorum being higher in calves than adults both in cattle (P = 0.017) and buffaloes (P < 0.0001). Sex-wise prevalence of helminths was higher in males than females for buffaloes (P < 0.0001) and sheep (P = 0.014) in contrast to cattle and goats.

Ten years of research activities on tropical parasitology of dromedaries, cattle, and small ruminants in Mauritania

In the past, the essential part of the activity of the parasitology laboratory of the Centre National d'Elevage et de Recherches Vétérinaires (CNERV) was represented by diagnostic work that enabled the construction of an inventory of local parasitic fauna and a good collection of specimens. However, the small and irregular number of samples each year, led us to switch our activities in 1990 toward work that could better justify the existence of CNERV. We started work on applied research topics, such as tick-borne diseases, helminthology (nemathelminths and plathelminths), and trypanosomosis. These results were valorized through scientific publication and communication at international meetings. The most valuable information was conveyed to herders.

Natural evolution of gastrointestinal nematodes in goats (Capra hircus) in the semi-arid ecosystem of the Paraíba backwoods, northeastern Brazil

This study was conducted in Patos county, a semi-arid area with caatinga vegetation in Paraiba State, northeastern Brazil. Twenty-four male goats of mixed breeds were used. The animals were separated in age groups from 1-12 months, i. e., 1-2, 3-4, 5-6, 7-8, 9-10, 11-12 months, with four animals in each group. The animals were slaughtered and necropsied to recover and identify adult worms. The goats were exposed to nematode infection from the first month of life. The most prevalent nematodes in decreasing order were: Trichostrongylus colubriformis, Haemonchus contortus and Oesophagostomum columbianum. Age of the goats did not appear to be a factor in resistance to gastrointestinal nematode infection. Worm burdens of 11-12 month old animals were significantly (P<0.05) higher than in other age groups.

Hypobiosis of Haemonchus contortus in natural infections of sheep and goats in a semi-arid area of Kenya

A total of 42 lambs, 42 kids, 21 ewes and 21 does were necropsied during an investigation of the epidemiology of Haemonchus contortus infection of sheep (Red Maasai) and goats (Small East African Goat) in a semi-arid area of Kenya. Availability and establishment of the infective stages were monitored by the necropsy of 21 tracer lambs and 21 tracer kids. Prevalence of H. contortus was over 90% in both sheep and goats and this species contributed to about 80% of the total worm burden. Only about 10% of the hypobiotic larvae were recovered from the mucosal digest whereas about 90% were recovered from the abomasal contents and washings, thereby suggesting that hypobiotic larvae may be loosely attached to the abomasal mucosa from which they may be dislodged during the processing of the abomasa for examination. Throughout the study, both adult worms and hypobiotic larvae were found in proportions that varied with seasons. Statistically, a higher proportion of hypobiotic larvae was found during the dry months than during the wet months, an indication that hypobiosis was an important feature in the survival of H. contortus during the dry months. Negligible worm burdens were acquired by the tracers during the short rains, suggesting that few H. contortus larvae survived on pasture in this season. The effectiveness of strategic control using ivermectin varied according to the timing in relation to the wet season. Treatment did not influence the seasonal pattern of hypobiosis but the treatment administered before the onset of the rains significantly reduced the numbers of both hypobiotic larvae and the adult worms. Treatment during the rains conferred a temporary relief of adult worm burden but had no impact on hypobiotic larvae.

Some aspects of inhibited development of trichostrongylids in ruminants

Inhibited development is an important aspect of the biology of some gastrointestinal nematodes of ruminants, particularly species of the subfamily Ostertagiinae and Haemonchus spp. There is a seasonality in the occurrence of the phenomenon. It tends to occur predominantly during the unfavourable season for the free-living stages. Thus 'winter' and 'summer-dry season' patterns of inhibition can be observed. Furthermore, the phenomenon is influenced by immunity of the host and by management factors. Different studies show conflicting results on the phenomenon of inhibition. This is examplified by studies related to H. contortus in small ruminants. Other studies indicate that large differences in propensity for inhibition can indeed occur in a single region. However, it has to be stressed that inadequate necropsy techniques can easily result in underestimation of the proportion of inhibited larvae, particularly in Haemonchus spp. in cattle. The macrocyclic lactones are highly effective against inhibited larvae of gastrointestinal nematodes. Treatment may even prevent establishment of inhibited larvae of Ostertagia and Trichostrongylus axei up to 1 month after treatment. The efficacy of benzimidazoles seems to be lower in the middle of the 'inhibition' period than at the beginning or the end. Some studies indicated that the presence of inhibited stages may be important for the build up of immunity. However, removal of high inhibited O. ostertagi burdens at housing does not impair development of immunity. Very little progress has been made on the molecular mechanisms of inhibited development.

Adaptation to arid environment: Haemonchus longistipes in dromedaries of Saharo-Sahelian areas of Mauritania

The adaptations of the trichostrongylid nematode Haemonchus longistipes of dromedaries (Camelus dromedarius) to the harsh environment of Saharo-Sahelian climate were assessed by means of (i) an epidemiological survey of dromedary infection in the south-west of Mauritania, (ii) an estimate over a 3 year period of parasite distribution within the host population and of prolificacy of H. longistipes females recovered from natural populations of infected dromedaries sampled at Nouakchott's slaughterhouse, and (iii) experimental infections of young dromedaries during three different periods of the year (end of the rainy season, middle and end of the dry season). Egg excretions (estimated by faecal egg counts), infective larvae derived from eggs as well as female prolificacy showed a marked seasonal pattern: high values in the rainy season and very low values in the dry season (especially March and April). Female prolificacy differed slightly between morphotypes: the knobbed type excreting over a longer period than the linguiform and smooth types. Following experimental infections in young dromedaries, arrest of larval development took place irrespective of the period. The survival strategy of H. longistipes in the dry season was based only on arrested larval development. Patent infections occurred from July to October, i.e. during the rainy season and was facilitated by the conjunction of high prevalence and intensity of adult worm burdens associated with high female prolificacy.