Survival and Transstadial Persistence of Trypanosoma cruzi in the bed bug (Hemiptera: Cimicidae).

Bed bug populations are increasing around the world at an alarming rate and have become a major public health concern. The appearance of bed bug populations in areas where Chagas disease is endemic raises questions about the role of these insects in the transmission of Trypanosoma cruzi, the etiological agent of the disease. In a series of laboratory evaluations, bed bug adults and nymphs were experimentally fed with T. cruzi-infected blood to assess the ability of T. cruzi to survive inside the bed bug and throughout the insect's molting process. Live T. cruzi were observed in gut contents of experimentally infected bed bug adults via light microscopy and the identity of the parasite was confirmed via polymerase chain reaction analysis. T. cruzi persisted at least 97-d postinfection in adult bed bugs. Nymphal stage bed bugs that were infected with T. cruzi maintained the parasite after molting, indicating that transstadial passage of T. cruzi in bed bugs took place. This report provides further evidence of acquisition, maintenance, and for the first time, transstadial persistence of T. cruzi in bed bugs.

Trypanosoma cruzi Infection Does Not Decrease Survival or Reproduction of the Common Bed Bug, Cimex lectularius.

Although not presently implicated as a vector of human pathogens, the common bed bug, Cimex lectularius, has been suspected of carrying human pathogens because of its close association with humans and its obligate hematophagy. Recently, we characterized the vectorial competence of C. lectularius for the parasite Trypanosoma cruzi, the causative agent of Chagas disease. We observed that C. lectularius can acquire T. cruzi infection when fed on T. cruzi-carrying mice, and subsequently transmit T. cruzi to uninfected mice. This led us to ask why has C. lectularius not been implicated in the transmission of T. cruzi outside of the laboratory? We hypothesized that T. cruzi reduces C. lectularius fitness (i.e., survival and/or reproduction) as an explanation for why C. lectularius does not to transmit T. cruzi in natural settings. We tested this hypothesis by comparing the survival and reproduction of uninfected and T. cruzi-infected C. lectularius. We observed that T. cruzi had a variable effect on C. lectularius survival and reproduction. There were negligible differences between treatments in juveniles. Infected adult females tended to live longer and produce more eggs. However, no effect was consistent, and infected bugs showed more variation in survival and reproduction metrics than control bugs. We did not observe any negative effects of T. cruzi infection on C. lectularius survival or reproduction, suggesting that decreased fitness in T. cruzi-infected C. lectularius is not why bed bugs have not been observed to transmit T. cruzi in natural settings.

Medical Entomology: A Reemerging Field of Research to Better Understand Vector-Borne Infectious Diseases.

In the last decade, the Chikungunya and Zika virus outbreaks have turned public attention to the possibility of the expansion of vector-borne infectious diseases worldwide. Medical entomology is focused on the study of arthropods involved in human health. We review here some of the research approaches taken by the medical entomology team of the University Hospital Institute (UHI) Méditerranée Infection of Marseille, France, with the support of recent or representative studies. We propose our approaches to technical innovations in arthropod identification and the detection of microorganisms in arthropods, the use of arthropods as epidemiological or diagnostic tools, entomological investigations around clinical cases or within specific populations, and how we have developed experimental models to decipher the interactions between arthropods, microorganisms, and humans.

IDENTIFICATION OF BAT ECTOPARASITE LEPTOCIMEX INORDINATUS FROM BAT-DWELLING CAVE, KANCHANABURI PROVINCE, THAILAND.

Bat bugs are blood-feeding insects of bats or warm blooded animals and humans. Since 2011, Leptocimex spp (Heteroptera: Cimicidae) has been reported in Thailand. However, microscopic examination of Leptocimex spp is complicated, especially when the entire body of the specimen is not available. To confirm the phenotypic identification of L. inordinatus from a limestone bat cave in Thailand, partial fragments of mitochondrial cytochrome c oxidase subunit 1 (COI) gene and 16S mitochondrial ribosomal DNA were PCR amplified and sequenced, which revealed 97% sequence identity with Cimicidae family members, being most similar to Cacodminae gen. sp. and C. vicinus, both bat bugs. Phylogenetic tree construction showed that L. inordinatus has a separate genetic lineage from that of with human bed bugs (Cimex hemipterus or C. lectularius), swallow bugs and other tick species. The presence of L. inordinatus in a bat-dwelling cave frequented by humans presents a potential public health problem requiring attention in particular regarding the possibility of zoonotic transmission of pathogens.

Bed bugs (Cimex lectularius) as vectors of Trypanosoma cruzi.

Populations of the common bed bug, Cimex lectularius, have recently undergone explosive growth. Bed bugs share many important traits with triatomine insects, but it remains unclear whether these similarities include the ability to transmit Trypanosoma cruzi, the etiologic agent of Chagas disease. Here, we show efficient and bidirectional transmission of T. cruzi between hosts and bed bugs in a laboratory environment. Most bed bugs that fed on experimentally infected mice acquired the parasite. A majority of previously uninfected mice became infected after a period of cohabitation with exposed bed bugs. T. cruzi was also transmitted to mice after the feces of infected bed bugs were applied directly to broken host skin. Quantitative bed bug defecation measures were similar to those of important triatomine vectors. Our findings suggest that the common bed bug may be a competent vector of T. cruzi and could pose a risk for vector-borne transmission of Chagas disease.

Bedbugs.

Cimex lectularius (the "bedbug") is an insect that feeds nocturnally, taking a requisite blood meal from a sleeping human or other parasitized host. Immunological reactions to bedbug saliva vary, but typically, bites yield erythematous and pruritic papules. The face and distal extremities, areas uncovered by sleeping clothes or blankets, are preferentially involved. Until the late 1990s, bedbug infestations in the United States were declining. Resurgence is attributed to increased travel and resistance to insecticides. Although hepatitis or human immunodeficiency virus is not effectively transmitted by the bedbug, pruritus and the fear and perceived violation of an infestation can be debilitating. Bedbugs are small but robust, and their ability to remain ensconced in crevices within the bedroom makes eradication difficult. As more patients present with bedbug bites, physicians must possess the knowledge to diagnose, treat, and educate with regard to bedbug bites and bedbug infestations.

Bedbugs: an equal opportunist and cosmopolitan creature.

Currently there is a rise in bedbugs seen in schools. The wingless, blood-sucking insects can arrive at school via student book bags, student clothing, or other personal items. If a student presents in the health office with a bite mark, the school nurse will need to differentiate between a bedbug bite and other insect bites, such as fleas, spiders, and scabies in order to provide the most accurate and appropriate intervention measures. This article will further provide school nurses with information about the etiology of the bedbug, mode of transmission, and eradication options for the school and community setting.

Laboratory evaluations of insecticide product efficacy for control of Cimex lectularius.

A susceptible, laboratory strain of bed bug, Cimex lectularius L., was used to determine the efficacy of insecticide products labeled or possessing a site label for bed bug control. Field strain bed bugs also were used to evaluate one insecticide product. The lethal time (LT),, values calculated for the laboratory strain bed bugs indicated that all of the pyrethroid products killed significantly faster than chlorfenapyr (0.5% [AIl; Phantom: BASF; LT50 = 10 d and 9 h). lamda-Cyhalothrin (0.03%; Demand CS; Syngenta) was the fastest acting insecticide (LT50 = 20 min), followed by bifenthrin (0.02% [AI]; Talstar One, FMC; LT50 = 53 min), deltamethrin (0.06% [AI]; Suspend SC; Bayer; LT50 = 61 min), and permethrin (0.05%; Dragnet SFR; FMC; LT50 = 88 min). The field strain bed bugs exposed to deltamethrin had an LT50 value of 14 day 8 h, indicating that the field strain was significantly less susceptible to deltamethrin than the laboratory strain. Chlorfenapyr exposure did not prevent the laboratory strain bed bugs from mating and laying eggs, nor did it prevent the eggs from hatching during the 2-wk exposure period. Surprisingly, none of the insecticides tested, including the pyrethroids, were repellent to laboratory strain bed bugs. Bed bugs rested on pyrethroid-treated panels and remained in contact with the panels until they died (2 h). Chlorfenapyr was also not repellent to bed bugs, but it caused no mortality during the 2-h test period. This study suggests that although pyrethroids were effective for controlling laboratory strain bed bugs, there is the potential for significant resistance in field strains. This study also determined that pyrethroid products were not repellent to bed bugs and would not cause bed bug aggregations to scatter or avoid treated surfaces.

Distribución topográfica de pimeliaphilus zeledoni acari pterygosomatidae en su hospedador triatoma dimidiata latreille, 1811 hemiptera reduviidae / Topographic distribution of pimeliaphilus zeledoni acari pterygosomatidae on its host triatoma dimidiata latreille, 1811 hemiptiera reduviidae

Se realizó una caracterización de la infestación de P. zeledoni en ejemplares costarricenses de T. dimiata. La prevalencia de infestación encontrada en 47 chinches fue del 53,2 por ciento, siendo las ninfas de 5º estadio las formas evolutivas que mostraron la densidad de infestación más alta (alfa 0,05). Las coxas constituyeron el sitio anatómico de los insectos donde los ácaros se localizaron preferencialmente. No se pudo determinar la presencia de efectos patogénicos importantes generados por los ácaros en los triatominos por lo que su aplicación en su control biológico debería ser considerada

Schizotrypanum in British bats.

Two species of Schizotrypanum, T. (S.) dionisii and T. (S.) vespertilionis, were identified from British bats. Laboratory studies on stocks of isolated trypanosomes from 5 species of bat (Pipistrellus pipistrellus, Nyctalus leisleri, N. noctula, Eptesicus serotinus and Myotis brandti) indicated that the predominant species was T. d. dionisii. Collections and dissection of the bat bug Cimex pipistrelli from bat roosts revealed flagellate infection in a total of 12 out of 20 bugs; 7 of these bugs had metacyclic trypanosomes present. C. pipistrelli and the human bed bug, C. lectularius were reared in the laboratory and allowed to feed on wild-caught bats known to be infected with T. d. dionisii. Development occurred in both species of Cimex. Cimex spp. could be used to detect subpatent Schizotrypanum infections by xenodiagnosis. This technique was used to test the parasitological status of bats collected in the wild or reared in captivity. On a single occasion an apparent transmission of T. d. dionisii to an uninfected (by xenodiagnosis) laboratory reared bat was achieved. A stock of Schizotrypanum isolated from a wild-caught C. pipistrelli collected in a N. leisteri roost was identified by DNA buoyant density centrifugation as T. (S.) vespertilionis. A P. pipistrellus known to be infected with T. d. dionisii was found to have cyst-like structures in thoracic skeletal muscle containing amastigotes. The study provided the strongest evidence yet that C. pipistrelli is the vector of Schizotrypanum in British bats.

Trypanosoma (Megatrypanum) incertum from Pipistrellus pipistrellus: development and transmission by cimicid bugs.

Trypanosoma (Megatrypanum) incertum Pittaluga 1905 was found in 33 out of 206 Pipistrellus pipistrellus caught at various sites in Britain. The trypanosome is described from blood smears. Development took place in laboratory-reared Cimex pipistrelli and Cimex lectularius. Epimastigote forms initially multiplied rapidly in the ventriculus and midgut of Cimex. Metacyclic trypanosomes were found in the rectum of both species of Cimex after 8 days when bugs were maintained at 20 degrees C and as early as 3 days at 30 degrees C. Electron microscopy of infected bugs revealed that there was no attachment to epithelial cells of the ventriculus or midgut, but within the rectum epimastigotes were attached by their flagella to the cuticle of the rectum by hemidesmosomes. Transmission was achieved by feeding experimentally infected bugs to bats kept in the laboratory. These bats were negative as judged by xenodiagnosis using laboratory-reared Cimex. Bats which had been caught in the wild demonstrated low-grade or sub-patent parasitaemias (positive in xenodiagnosis) for up to 400 days after the day of capture. Despite an extensive search of impression smears of tissues immediately after trypanosomes first appeared in the blood of experimentally infected bats no multiplicative stages were found.

Natural and experimental infection of bedbugs with Wuchereria bancrofti in British Guiana

In Georgetown, British Guiana, 100 Cimax hemipterus (older nymphs and adults) were collected from a bed used by two persons who were positive and two persons who were negative for the microfilariae of Wuchereria brancrofti. Eighty-three of the bedbugs contained at least one living or dead parasite. Early first stage larvae were found in the abdomen, thorax, legs, and antennae. Eight bugs had a total of 9 sausage forms, of which 2 were dead and 3 apparently moribund. Also found were 2 sluggish second stage larvae and 3 infective larvae of which 2 were non-motile. Rupture of the stomach from overengorgement and consequent release of the parasites into the hemocoele was observed in 12 bugs. The development of W. bancrofti was studied in five lots of bedbugs fed on a human carrier having 165 to 200 microfilariae per 20 cmm of blood at the time of feeding. Little development occurred in 100 first- and second- instar nymphs, which sucked up relatively few parasites. Four lots of 50 older bedbugs were given, respectively, 0, 1, 2, and 3 non-infective meals at 4-day intervals after the infective meal. It was found that as the number of additional feedings increased, the parasites survived longer and developed further. No infective larvae had developed by the 20th day. Because the mortality of larvae was high in both natural and experimental infections, only a few developed to more advanced stages, it is concluded that C. hemipterus is not a suitable host for W. brancrofti (Summary)