Carriage of bacteria by proboscises, legs, and feces of two species of flies in street food vending sites in Ouagadougou, Burkina Faso

Detection and antimicrobial resistance profiles of Salmonella enterica recovered from house fly intestinal tracts and environments of selected broiler farms in Texas

The entry of drug-resistant Salmonella enterica into the food supply is a challenge to public health and food safety. One emerging concern is the role of synanthropic insects for moving microbial pathogens throughout poultry production systems, where insects commonly thrive. We investigated the presence and phenotypic antimicrobial susceptibility of S. enterica from insect and environmental samples from broiler farms. Insects were collected throughout the broiler house and adjacent compost barn. Environmental samples (poultry feed, drinking water, fresh litter, and feces) were collected simultaneously (n = 80). Insect gastrointestinal tracts were dissected and pooled (n = 57). Recovered Salmonella isolates were serotyped and subjected to antimicrobial susceptibility testing against 14 medically important antimicrobials. Overall, six isolates were recovered from 137 total samples (4.4%): 3.5% (2/57) from adult house flies (Musca domestica), 15% (3/20) from poultry feed, and 4.8% (1/21) from litter. Salmonella Montevideo (16.7%; 1/6), Typhimurium (33.3%; 2/6), and Kentucky (50%, 3/6) were identified. All but one Salmonella isolate (83.3%; 5/6) demonstrated resistance to at least one antimicrobial. Further research should investigate movement patterns between broiler operations and food processing facilities to establish efficient biosecurity measures to prevent any instances of foodborne pathogen transmission into human food systems.

Flies as Vectors and Potential Sentinels for Bacterial Pathogens and Antimicrobial Resistance: A Review

The unique biology of flies and their omnipresence in the environment of people and animals makes them ideal candidates to be important vectors of antimicrobial resistance genes. Consequently, there has been increasing research on the bacteria and antimicrobial resistance genes that are carried by flies and their role in the spread of resistance. In this review, we describe the current knowledge on the transmission of bacterial pathogens and antimicrobial resistance genes by flies, and the roles flies might play in the maintenance, transmission, and surveillance of antimicrobial resistance.

Risk factors for Salmonella enterica subsp. enterica persistence in broiler-chicken flocks on Reunion Island

This study was conducted to identify the main risk factors for Salmonella spp. persistence in broiler flocks in Reunion Island. Seventy broiler farms were surveyed from March 2016 to June 2018. Samples of fresh droppings were collected using gauze socks, and a questionnaire was completed with the farmers. Persistence was defined as an infection with the same serovar before and after cleaning and disinfection (C/D) of poultry houses. Salmonella spp. was found to persist on 27% of the farms. Cleaning concrete surrounding areas (OR = 0.23) and disinfecting silos (OR = 0.17) reduced the risk of pathogen persistence. An analysis of infections of pests found in the vicinity of the farms confirmed their role in the persistence of Salmonella spp. Fifteen percent of the pests were infected and the presence of mealworms in poultry litter (OR = 6.69) was found to increase the risk of Salmonella spp. persistence. We conclude that improved cleaning-disinfection, sanitary preventive measures and pest control in the poultry sector are needed to avoid the persistence of Salmonella spp. on broiler farms.

Fly foregut and transmission of microbes

Two areas of research that have greatly increased in attention are: dipterans as vectors and the microbes they are capable of vectoring. Because it is the front-end of the fly that first encounters these microbes, this review focuses on the legs, mouthparts, and foregut, which includes the crop as major structures involved in dipteran vectoring ability. The legs and mouthparts are generally involved in mechanical transmission of microbes. However, the crop is involved in more than just mechanical transmission, for it is within the lumen of the crop that microbes are taken up with the meal of the fly, stored, and it is within the lumen that horizontal transmission of bacterial resistance has been demonstrated. In addition to storage of microbes, the crop is also involved in depositing the microbes via a process known as regurgitation. Various aspects of crop regulation are discussed and specific examples of crop involvement with microorganisms are discussed. The importance of biofilm and biofilm formation are presented, as well as, some physical parameters of the crop that might either facilitate or inhibit biofilm formation. Finally, there is a brief discussion of dipteran model systems for studying crop microbe interactions.

Street food research worldwide: a scoping review

BACKGROUND

Street foods vary with respect to their nutritional value and safety characteristics and contribute to a sizable proportion of food intake in many populations worldwide. Therefore, the present study aimed to describe the coverage in the scientific literature of different health-related and socio-economic aspects of street food consumption and trading.

METHODS

Three electronic databases (searched from inception to 16 October 2017), a hand-search of relevant journals and backward citation tracking were used to identify eligible scientific articles with a main objective of investigating or reporting specific results on health-related or socio-economic aspects of street food. Papers published in English, Portuguese, French, Spanish or Italian, as well as English abstracts of papers published in other languages, were assessed. The selected articles were evaluated by two independent researchers and described according to year of publication, geographical distribution, definition of street food, main topics addressed and target population.

RESULTS

In total, 441 papers were selected. The number of publications has increased in recent years, almost half of them being published after 2012. Almost three-quarter of the articles were from Africa or Asia. Most studies addressed food safety (85.5%), whereas street food availability and consumption were much less frequently investigated (30.3%). The focus of the studies was usually the food (mostly its microbiological contamination) and the vendors (mostly their food handling), whereas consumers and vending sites were seldom evaluated. More than half of the studies did not specify a definition for street food.

CONCLUSIONS

Efforts are needed for a more widespread and comprehensive assessment of different issues related to street food availability and consumption in different settings, especially regarding street food offer, nutritional composition, and patterns of purchase and consumption by the population.

Effects of Bacterial Dose and Fly Sex on Persistence and Excretion of Salmonella enterica serovar Typhimurium From Adult House Flies (Musca domestica L.; Diptera: Muscidae)

Salmonella Typhimurium (Le Minor and Popoff 1987; Enterobacteriales: Enterobacteriaceae) is a pathogen that causes gastroenteritis in humans and can be harbored by house flies. Factors influencing excretion of S. Typhimurium from infected flies have not been elucidated but are essential for assessing transmission potential. We determined the persistence and excretion of a green fluorescent protein (GFP) expressing strain of S. Typhimurium from house flies. Individual male and female flies were fed either sterile Luria-Bertani (LB) broth (controls) or cultures of "high" (~105 colony forming units [CFU]) or "low" (~104 CFU) doses of bacteria (treatments). Bacterial persistence was determined over 16 h by culturing whole-fly homogenate. Both sex and dose affected persistence between 6 and 12 h postingestion. In a separate experiment, fly excretion events were monitored during this time interval and excreta droplets were individually cultured for bacteria. Female flies had more excretion events than males across treatments. We observed interactions of fly sex and bacterial abundance (dose), both on the proportion of Salmonella-positive droplets and the CFU shed per droplet (CFU/droplet). In the low-dose treatment, males excreted a greater proportion of positive droplets than females. In the high-dose treatment, males excreted more CFU/droplet than females. High-dose male flies excreted more CFU/droplet than low-dose males, but low-dose females excreted more CFU/droplet than high-dose females. Irrespective of sex, low-dose flies excreted a greater dose-adjusted CFU (CFU droplet/CFU fed) than high-dose flies. This study demonstrates that both bacterial abundance and fly sex may influence excretion of bacteria from flies, and should be considered when assessing the risk of house fly transmission of pathogens.

A systematic review of human pathogens carried by the housefly (Musca domestica L.)

BACKGROUND

The synanthropic house fly, Musca domestica (Diptera: Muscidae), is a mechanical vector of pathogens (bacteria, fungi, viruses, and parasites), some of which cause serious diseases in humans and domestic animals. In the present study, a systematic review was done on the types and prevalence of human pathogens carried by the house fly.

METHODS

Major health-related electronic databases including PubMed, PubMed Central, Google Scholar, and Science Direct were searched (Last update 31/11/2017) for relevant literature on pathogens that have been isolated from the house fly.

RESULTS

Of the 1718 titles produced by bibliographic search, 99 were included in the review. Among the titles included, 69, 15, 3, 4, 1 and 7 described bacterial, fungi, bacteria+fungi, parasites, parasite+bacteria, and viral pathogens, respectively. Most of the house flies were captured in/around human habitation and animal farms. Pathogens were frequently isolated from body surfaces of the flies. Over 130 pathogens, predominantly bacteria (including some serious and life-threatening species) were identified from the house flies. Numerous publications also reported antimicrobial resistant bacteria and fungi isolated from house flies.

CONCLUSIONS

This review showed that house flies carry a large number of pathogens which can cause serious infections in humans and animals. More studies are needed to identify new pathogens carried by the house fly.

Efficacy of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) on developmental stages of house fly, Musca domestica

The housefly, Musca domestica is a major domestic, medical and veterinary pest. The management of these flies reliance on insecticide, causes environmental constraints, insecticide resistance and residues in the meat, skin. Therefore one of the eco-friendly alternate methods is by using biological agents such as entomopathogenic nematodes (EPN). In the present study evaluated the survival of EPN species Steinernema feltiae, Heterorhabditis indica, S. carpocapsae, S. glaseri and S. abbasi in poultry manure and also their efficacy against different developmental stages of house fly. After exposing to poultry manure, S. feltiae showed more survival as followed by H. indica, S. carpocapsae, S. glaseri and S. abbasi in all exposition period. When the exposition period extended to 96 h, all nematode species survivability was drastically reduced. After exposing these nematodes to poultry manure at 24 h their virulence capacity against wax moth, Galleria mellonella showed all the nematode species were able cause 100% mortality. However their progeny production was significantly reduced. Fly eggs and pupae were refractory to these nematode infection. Petri dish without artificial diet assay showed that, second and 3rd-instar larvae were highly susceptible to EPNs as compared to larvae provided with artificial diet. H. indica showed high virulence capacity compared to other nematodes tested. Poultry manure assay revealed that, H. indica and S. carpocapsae caused minimal mortality where as S. feltiae, S. glaseri and S. abbasi did not cause any mortality. This may be because of poor survival and limited movement of nematodes in poultry manure which may be due to ammonia, other toxic substances in poultry manure. The decrease in larval mortality in manure suggests that biocontrol of housefly by using EPNs is unlikely.

Volatile Organic Compounds of Decaying Piglet Cadavers Perceived by Nicrophorus vespilloides

In the necrophagous burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae), cadaver preference appears to depend on cadaver size and on the maturity of the beetle. We previously showed that newly emerged females with immature ovaries prefer later stages of decomposition of large cadavers. Our present aim is the determination of specific chemical compounds involved in the discrimination of cadaveric odor bouquets and the recognition of specific stages of decomposition. We used headspace samples of maggot-infested piglet cadavers at various decomposition stages and performed gas chromatography coupled with electroantennography (GC-EAD) to record 45 EAD-active compounds. Using GC coupled with mass spectrometry, we identified 13 of the EAD-active compounds. The headspace of the fresh decomposition stage was characterized mainly by high relative amounts of trimethylpyrazine. High relative amounts of dimethyl trisulfide were characteristic of bloated, post-bloating, and advanced decay stages. The advanced decay and dry remains stages were dominated by high relative amounts of phenol. Statistically, this compound had the highest impact on discrimination between the fresh decomposition stage, which is important for mature burying beetles for reproduction, and the advanced decay stage, which is nutritionally more attractive for newly emerged beetles. Phenol might, therefore, function as a key substance for newly emerged female burying beetles, so that they can locate suitable cadavers for feeding to maturation.

Fungal dissemination by housefly (Musca domestica L.) and contamination of food commodities in rural areas of South Africa

Several insects that act as vectors, including houseflies (Musca domestica L.), are often considered to be an important source of fungal contamination in human foods. Houseflies are also involved in the transmission of bacterial pathogens that may pose a serious hazard to human health. Thus, the rural population of South Africa, as typified by that in the Gauteng Province investigated in this study, is at high risk from fungal exposure disseminated by houseflies and it is therefore important to assess the role of flies in contaminating various food commodities. Eighty four samples of houseflies (captured from households and pit toilets) were studied for their potential to carry fungal spores into food commodities. The fungi occurring in samples of raw maize (15) and porridge (19) were also assessed. Fungal isolates were identified based on morphological characteristics by conventional identification methods. Fifteen genera of fungi were isolated and identified, of which Aspergillus, Fusarium, Penicillium, Cladosporium, Moniliella and Mucor were the most prevalent in all three sample types analysed. The incidence rates of fungal contamination per total fungal count isolated in houseflies, maize and porridge were recorded with mean fungal load of 2×10(8) CFU/ml, 1×10(7)CFU/g and 2×10(7)CFU/g respectively. Additionally, A. flavus, A. parasiticus, F. verticillioides, F. proliferatum, P. verrucosum, P. aurantiogriseum and M. suaveolens were the most frequent fungal isolates in houseflies with incidence rate of 34%, 11%, 27%, 21%, 22%, 17% and 32% respectively. F. verticillioides, A. flavus, A. niger and P. oslonii were the most prevalent species contaminating porridge and maize with incidence rate of 23%, 32%, 16% and 28% in maize samples, while incidence rates of 59%, 15% and 29% were recorded in porridge samples with the exception of F. verticillioides. The prevalence of these genera of fungi may pose serious health risks.

Detection of foodborne bacterial pathogens from individual filth flies

There is unanimous consensus that insects are important vectors of foodborne pathogens. However, linking insects as vectors of the pathogen causing a particular foodborne illness outbreak has been challenging. This is because insects are not being aseptically collected as part of an environmental sampling program during foodborne outbreak investigations and because there is not a standardized method to detect foodborne bacteria from individual insects. To take a step towards solving this problem, we adapted a protocol from a commercially available PCR-based system that detects foodborne pathogens from food and environmental samples, to detect foodborne pathogens from individual flies.Using this standardized protocol, we surveyed 100 wild-caught flies for the presence of Cronobacter spp., Salmonella enterica, and Listeria monocytogenes and demonstrated that it was possible to detect and further isolate these pathogens from the body surface and the alimentary canal of a single fly. Twenty-two percent of the alimentary canals and 8% of the body surfaces from collected wild flies were positive for at least one of the three foodborne pathogens. The prevalence of Cronobacter spp. on either body part of the flies was statistically higher (19%) than the prevalence of S. enterica (7%) and L.monocytogenes (4%). No false positives were observed when detecting S. enterica and L. monocytogenes using this PCR-based system because pure bacterial cultures were obtained from all PCR-positive results. However, pure Cronobacter colonies were not obtained from about 50% of PCR-positive samples, suggesting that the PCR-based detection system for this pathogen cross-reacts with other Enterobacteriaceae present among the highly complex microbiota carried by wild flies. The standardized protocol presented here will allow laboratories to detect bacterial foodborne pathogens from aseptically collected insects, thereby giving public health officials another line of evidence to find out how the food was contaminated when performing foodborne outbreak investigations.

Prevalence and relative risk of Cronobacter spp., Salmonella spp., and Listeria monocytogenes associated with the body surfaces and guts of individual filth flies

Although flies are important vectors of food-borne pathogens, there is little information to accurately assess the food-related health risk of the presence of individual flies, especially in urban areas. This study quantifies the prevalence and the relative risk of food-borne pathogens associated with the body surfaces and guts of individual wild flies. One hundred flies were collected from the dumpsters of 10 randomly selected urban restaurants. Flies were identified using taxonomic keys before being individually dissected. Cronobacter spp., Salmonella spp., and Listeria monocytogenes were detected using the PCR-based BAX system Q7. Positive samples were confirmed by culture on specific media and through PCR amplification and sequencing or ribotyping. Among collected flies were the housefly, Musca domestica (47%), the blowflies, Lucilia cuprina (33%) and Lucilia sericata (14%), and others (6%). Cronobacter species were detected in 14% of flies, including C. sakazakii, C. turicensis, and C. universalis, leading to the proposal of flies as a natural reservoir of this food-borne pathogen. Six percent of flies carried Salmonella enterica, including the serovars Poona, Hadar, Schwarzengrund, Senftenberg, and Brackenridge. L. monocytogenes was detected in 3% of flies. Overall, the prevalence of food-borne pathogens was three times greater in the guts than on the body surfaces of the flies. The relative risk of flies carrying any of the three pathogens was associated with the type of pathogen, the body part of the fly, and the ambient temperature. These data enhance the ability to predict the microbiological risk associated with the presence of individual flies in food and food facilities.

Managing tsetse transmitted trypanosomosis by insecticide treated nets--an affordable and sustainable method for resource poor pig farmers in Ghana

An outbreak of tsetse-transmitted trypanosomiasis resulted in more than 50% losses of domestic pigs in the Eastern Region of Ghana (source: Veterinary Services, Accra; April 2007). In a control trial from May 4^th–October 10^th 2007, the efficacy of insecticide-treated mosquito fences to control tsetse was assessed. Two villages were selected – one serving as control with 14 pigsties and one experimental village where 24 pigsties were protected with insecticide treated mosquito fences. The 100 cm high, 150denier polyester fences with 100 mg/m² deltamethrin and a UV protector were attached to surrounding timber poles and planks. Bi-monthly monitoring of tsetse densities with 10 geo-referenced bi-conical traps per village showed a reduction of more than 90% in the protected village within two months. Further reductions exceeding 95% were recorded during subsequent months. The tsetse population in the control village was not affected, only displaying seasonal variations. Fifty pigs from each village were ear-tagged and given a single curative treatment with diminazene aceturate (3.5 mg/kg bw) after their blood samples had been taken. The initial trypanosome prevalence amounted to 76% and 72% of protected and control animals, respectively, and decreased to 16% in protected as opposed to 84% in control pigs three months after intervention. After six months 8% of the protected pigs were infected contrasting with 60% in the control group.

Sixty million people and more than 70 million livestock live in Africa at risk of contracting trypanosomiasis. The heads of member states of the African Union (AU) declared the year 2000 as the beginning of the Pan African Tsetse and Trypanosomiasis Eradication Campaign to eradicate tsetse flies and the diseases they transmit from the continent. For the first time the social and economic consequences of trypanosomiasis were brought to the attention of the affected populations. Efforts to control the fatal disease in man and livestock are based on treatment of patients and livestock with trypanocidal drugs. Resistance-related drug failures are increasing. Methods to control tsetse flies rely on insecticides. Past tsetse campaigns proved unsustainable due to the public good character of most control techniques such as aerial and ground spraying, traps or targets. Treating livestock with insecticides may be more sustainable and is also controlling ticks, which can transmit economically important and often fatal diseases. Costs per head of livestock and tick resistance against insecticides are seen as a major hindrance to their continuous large-scale use. Insecticide treated nets proved an effective and affordable means protecting pigs against tsetse transmitted trypanosomoses in Ghana.

The importance of carcass volatiles as attractants for the hide beetle Dermestes maculatus (De Geer)

A decaying cadaver emits volatile organic compounds that are used by necrophilous and necrophagous insects in order to find their brood substrate. Although volatile organic compounds (VOCs) that are released by carcasses have been identified, little is known about the specific compounds that are used by these insects while searching for a brood substrate. Therefore, we have investigated the chemical ecology involved in the attraction of the necrophagous hide beetle Dermestes maculatus, which feeds as an adult and larva upon decomposing carcasses. Our aims have been to identify the responsible compounds in the odours of the carcass that are important for the attraction of the beetles. Furthermore, we have studied sex- and age-related differences in beetle attraction and tested whether the hide beetle can distinguish between various stages of decomposition by means of the emitted odours. Headspace collection of volatiles released from piglet carcasses (bloated stage, post-bloating stage, advanced decay and dry remains), coupled gas chromatography-mass spectrometry (GC-MS), gas chromatography with electroantennographic detection (GC-EAD) and bioassays were conducted to identify the volatiles responsible for the attraction of the beetles. Freshly emerged male beetles were attracted by the odour of piglets in the post-bloating stage (9 days after death; T(mean) = 27 °C) and the EAD-active compound benzyl butyrate. Statistical analysis revealed a higher relative proportion of benzyl butyrate in the odour bouquet of the post-bloating stage in comparison with the other stages. We therefore conclude that this compound plays an important role in the attraction of hide beetles to carcass odour. This underlines the potential use of D. maculatus for the estimation of the post mortem interval. The decomposition stage at which the female beetles are attracted to the odour of a cadaver remains unknown, as does the nature of this attraction. Pheromones (sexual or aggregation pheromones) might play an essential role correlated with their attraction to carrion and consequently with their attraction to the substrate for mating and ovipositioning.

Review of the carriage of zoonotic bacteria by arthropods, with special reference to Salmonella in mites, flies and litter beetles

This systematic review considers the relationship between arthropods commonly found in and around livestock premises and zoonotic bacteria. The principal focus is upon insects and arachnids on poultry units, where houses, litter and manure provide good conditions for the growth, multiplication and protection of flies, beetles and mites, and where zoonotic pathogens such as Salmonella and Campylobacter are prevalent. Other members of the Enterobacteriaceae and the taxa Clostridium, Helicobacter, Erysipelas and Chlamydiaceae are also discussed. Salmonella is widely distributed in the flies of affected livestock units and is detectable to a lesser degree in beetles and mites. Persistent carriage appears to be common and there is some field and experimental evidence to support arthropod-mediated transmission between poultry flocks, particularly carry-over from one flock to the next. Campylobacter may readily be isolated from arthropods in contact with affected poultry flocks, although carriage is short-lived. There appears to be a role for flies, at least, in the breaching of biosecurity around Campylobacter-negative flocks. The carriage of other zoonotic bacteria by arthropods has been documented, but the duration and significance of such associations remain uncertain in the context of livestock production.

The Australian bush fly (Musca vetustissima) as a potential vector in the transmission of foodborne pathogens at outdoor eateries

Abstract Australian outdoor activities are often accompanied by a barbeque (BBQ) with family, friends, and guests, which are often interrupted by uninvited guests in the form of the Australian bush fly, Musca vetustissima. We investigated the bacterial loading associated with the Australian bush in three different environments: on a cattle farm, in a typical urban area (shopping center car park), and at a BBQ. The highest bacterial populations per fly were found to occur in a farm environment ( approximately 9.1 x 10(4) CFU per fly), whereas the bacterial population was lowest on flies caught in an urban environment ( approximately 1.9 x 10(4) CFU per fly). The median CFU per fly caught near a BBQ was approximately 5.0 x 10(4). Escherichia coli was the most commonly isolated potential pathogen, whereas Shigella sp. was the least common bacterial isolate that was screened. All isolated foodborne pathogens or indicator bacteria were screened for antibiotic resistance against commonly prescribed antibiotics. This revealed a very high prevalence of multidrug resistance, especially among the Salmonella and Shigella isolates of 94% and 87% resistance, respectively, against amoxicillin, roxythromycin and cefaclor.

Protection of confined cattle against biting and nuisance flies (Muscidae: Diptera) with insecticide-treated nets in the Ghanaian forest zone at Kumasi

Insecticide-treated nets for the protection of cattle against Muscinae and Stomoxyinae were evaluated using four identical pens in Kumasi, Ghana, 2005. Two pens served as controls: pen A as negative control and pen C as a positive control containing two zebus and no netting protection. Pens B and D had two zebus each: B was protected with an untreated net (1 m height) while D had the same but deltamethrin-treated net with a persistency attaining 9 months. Nuisance fly densities were weekly monitored using mono-conical traps outside each pen at distances of 20-30 m. No Glossinidae were detected in an otherwise suitable habitat and fewer than ten Tabanidae per catch were recorded. Insect attacks were counted twice per week with photos of selected body regions. Video footages of each animal allowed recordings of defensive movements during 30 s. For the first 3 weeks, mean outside catches were highest around B and C with, respectively, 9.0 and 8.0 insects per trap per day compared with catches outside A and D with 1.8 and 3.3 insects. Catches increased sharply around pens B and C with, respectively, 155.7 and 172.8 insects during week 4 and following, while outside pens A and D significantly fewer insects (11.8 and 7.3) were caught. Pictures of selected body regions showed significantly fewer attacking insects inside pen D, leading to significant nuisance reductions. Feed-uptake and resting was undisturbed, contrasting with relentless disturbance of animals in pens B and C. Protecting confined cattle with a treated net prevented attacks by nuisance insects and reduced their densities.

Competence of the housefly, Musca domestica, as a vector of Microsporum canis under experimental conditions

The role of Musca domestica Linnaeus as a vector of the dermatophyte Microsporum canis was investigated under experimental laboratory conditions. About 400 4-day-old M. domestica flies were divided into two groups. Group A consisted of about 200 infected flies and group B comprised about 200 uninfected flies that were used as controls. Each trial was run three times. Flies from group A were fed for 24 h with a solution of ultra-high temperature-treated (UHT) milk containing about 10(6) colony-forming units (CFU) per mL of M. canis (infected milk inoculum [IMI]). The control group (group B) was fed with only UHT milk spiked with a teaspoon of honey. Microsporum canis was detected from faeces, vomitus, external surfaces and internal organs of 20 adult flies, eggs, first-, second- and third-stage (L1, L2, L3) larvae and pupae of each group, as well from 20 adult newly emerged flies (NEFs; from infected generations only). Samples were collected at 2, 4, 6 and 24 h post-infection (p.i.) (i.e. the times at which IMI was available) and on 2, 5, 7 and 8 days p.i. from adult flies, faeces and vomitus. Eggs, L1, L2, L3 and pupae were processed as soon as they appeared. Equivalent samples were taken from group B. All the samples were individually cultured. Microsporum canis was not isolated from the control group, from eggs, larvae, pupae or NEFs, or from faeces and vomitus, although it was detected on the body surface (26.2%) and internal organs (26.9%) of adult flies. The highest positivity for M. canis was detected on flies within the first 6 h p.i. (i.e. 57.2% on the body surface and 71.6% in the internal organs). No M. canis was isolated at 24 h p.i., but it was isolated from the body surface only at 2 and 5 days p.i. The results presented provide evidence that M. domestica transmits M. canis mechanically with its outer body surface for up to 5 days p.i., but does not do so through its vomitus and faeces or transovarially. The role played by M. domestica in the epidemiology of human and animal dermatophytoses is discussed.

Types and numbers of sensilla on antennae and maxillary palps of small and large houseflies, Musca domestica (Diptera, Muscidae)

Houseflies, Musca domestica, obtained from a high-larval-density culture were significantly (ca. 1.5 times) smaller than those from a low-larval-density culture. The same held true for their antennae and maxillary palps. Structure, number, and distribution of sensilla on antennae and palps of small and large flies were investigated using Scanning electron microscopy and Transmission electron microscopy. In each funiculus three pits were present, two (Type I) consisting of several compartments and one (Type II) of one compartment. Four types of olfactory sensilla were detected: trichoid sensilla on the funiculi, basiconic sensilla on funiculi and palps, grooved sensilla on funiculi and in pits Type I, and clavate sensilla on funiculi and in pits Type II. Type I pits also contained striated sensilla (presumably hygroreceptors). Mechanosensory bristles were present on scapes, pedicels, and palps. Noninnervated microtrichia were found on the palps and all antennal segments. The large houseflies possessed nearly twice as much sensilla as the small flies. So far, we did not observe differences in behavior between small and large flies. We assumed that small flies, being olfactory less equipped than large flies, may be able to compensate for this by, e.g., visual cues or by their olfactory sensilla being more sensitive than those of large flies. To be able to answer these questions careful studies have to be done on the behavioral responses of small and large flies to environmental stimuli. In addition, electrophysiological studies should be performed to reveal whether the responses of individual sensilla of flies reared under different conditions have been changed.

Darkling beetles (Alphitobius diaperinus) and their larvae as potential vectors for the transfer of Campylobacter jejuni and Salmonella enterica serovar paratyphi B variant Java between successive broiler flocks

Broiler flocks often become infected with Campylobacter and Salmonella, and the exact contamination routes are still not fully understood. Insects like darkling beetles and their larvae may play a role in transfer of the pathogens between consecutive cycles. In this study, several groups of beetles and their larvae were artificially contaminated with a mixture of Salmonella enterica serovar Paratyphi B Variant Java and three C. jejuni strains and kept for different time intervals before they were fed to individually housed chicks. Most inoculated insects were positive for Salmonella and Campylobacter just before they were fed to the chicks. However, Campylobacter could not be isolated from insects that were kept for 1 week before they were used to mimic an empty week between rearing cycles. All broilers fed insects that were inoculated with pathogens on the day of feeding showed colonization with Campylobacter and Salmonella at levels of 50 to 100%. Transfer of both pathogens by groups of insects that were kept for 1 week before feeding to the chicks was also observed, but at lower levels. Naturally contaminated insects that were collected at a commercial broiler farm colonized broilers at low levels as well. In conclusion, the fact that Salmonella and Campylobacter can be transmitted via beetles and their larvae to flocks in successive rearing cycles indicates that there should be intensive control programs for exclusion of these insects from broiler houses.

Fatal ulcerative colitis in a western lowland gorilla (Gorilla gorilla gorilla)

A captive western lowland gorilla (Gorilla gorilla gorilla) presented with watery diarrhoea that progressed to become profuse and haemorrhagic. Faecal analyses revealed Balantidium (B.) coli trophozoites and salmonella-like bacteria. Despite treatment the gorilla died on the 5th day after onset of symptoms. Post-mortem examination revealed a severe erosive-ulcerative superficial and deep colitis. Histological examination of post-mortem samples of the colon showed plentiful B. coli invading into the mucosa and submucosa, whilst PCR screening of bacterial DNA could not confirm any bacteria species which could be connected to the clinical picture. As B. coli is usually a non-pathogenic gut commensal, and as this animal previously showed evidence of non-symptomatic infection of B. coli, it is possible that the switch in pathogenicity was triggered by an acute bacterial infection. Despite successful treatment of the bacterial infection the secondary deep invasion of B. coli was not reversed, possibly because of the failure of the treatment regimen, and led to the death of the gorilla.

[Shigellosis or bacillary dysentery]

Shigellosis, commonly known as bacillary dysentery, is an enterobacterial disease caused by the Shigella genus, which now belongs to the Escherichia tribe, because of their genetic and phenotypic similarities. S. sonnei, flexneri, boydii and dysenteriae differ in their epidemiologic and pathogenic characteristics. S. sonnei is predominant in industrialized countries and causes the mildest disease. S. dysentery is especially dangerous because it occurs in outbreaks, sometimes in catastrophic situations, and has a high mortality rate. Shigellosis typically causes watery diarrhea followed by dysentery. It may be associated with a variety of mild to severe or even life-threatening complications. Shigellosis is a significant public health problem in developing countries where it remains a major cause of diarrhea-related morbidity and mortality, especially among children. Annual cases worldwide are estimated at 160 million. Shigellosis is a highly contagious disease of poor and crowded communities, with fecal-oral (hand-to-mouth) transmission, and an extremely low minimum infectious dose. Multidrug resistance is a serious problem. Ciprofloxacin is the first-line antibiotic, recommended for 3 days. Prevention and control should include personal hygiene, hand washing, sanitation, and water supply. No vaccine is available, but several candidates are currently being evaluated.