Equine attachment site preferences and seasonality of common North American ticks: Amblyomma americanum, Dermacentor albipictus, and Ixodes scapularis.

BACKGROUND: Ticks are common on horses, but recent publications characterizing equine tick infestations in North America are lacking. METHODS: To further understand attachment site preferences of common ticks of horses, and to document the seasonality of equine tick infestation in northeastern Oklahoma, horses from eight farms were evaluated twice a month over a 1-year period. Each horse was systematically inspected beginning at the head and moving caudally to the tail. Attachment sites of ticks were recorded and all ticks collected were identified to species and stage. RESULTS: Horses (26 males and 62 females) enrolled in the study ranged in age from 1 to 23 years (mean = 12, 95% CI 11-13). A total of 2731 ticks were collected; 84.1% (74/88) of the horses were infested (median = 3 ticks) at one or more examinations. Five tick species were identified, including Amblyomma americanum (78.2%; 2136/2731), Ixodes scapularis (18.2%; 497/2731), Dermacentor albipictus brown variant (2.6%; 71/2731), Dermacentor variabilis (0.7%; 20/2731), and Amblyomma maculatum (0.3%; 7/231). Most ticks were adults (83.6%; 2282/2731), but immature A. americanum (436/2136; 20.4%), D. albipictus (12/71; 16.9%), and A. maculatum (n = 1) were occasionally recovered. Amblyomma americanum were most often attached to the inguinal area, and I. scapularis and D. albipictus were most commonly found on the chest and axillary region (P < 0.0001). Ticks were found on horses in every month of the year. The largest number of ticks (638/2731; 23.4%) were collected in May (P < 0.0001). Amblyomma americanum, primarily immature, was the only tick recovered in September, I. scapularis and D. albipictus predominated October through February, and both A. americanum and I. scapularis were common in March. In the warmer months, April through August, A. americanum was the most common tick, followed by D. variabilis and A. maculatum. CONCLUSIONS: This research confirms that ticks common on horses in North America have attachment site preferences and that ticks infest horses in Oklahoma throughout the year, including during the winter. Additional research is warranted to fully understand the risk these infestations pose to equine health.

Identification of a new vector species of avian haemoproteids, with a description of methodology for the determination of natural vectors of haemosporidian parasites.

BACKGROUND: Haemosporidian parasites are transmitted by dipteran blood-sucking insects but certain vectors remain unidentified for the great majority of described species. Sensitive PCR-based methods are often used for the detection of haemosporidian infection in wild-caught insects. However, this approach alone cannot distinguish between different sporogonic stages and thus is insufficient to demonstrate that the parasites produce the infective stage (sporozoite), which is essential for transmission. To prove that PCR-positive insects could act as vectors, the record of sporozoites is needed. We developed a methodology for the determination of natural vectors of avian Haemoproteus species and other haemosporidians. The essence of this approach is to apply PCR-based and microscopic diagnostic tools in parallel for sporozoite detection in insects. METHODS: Culicoides biting midges transmit avian Haemoproteus parasites, but certain insect species, which are involved in transmission, remain insufficiently investigated. Biting midges were collected in the wild and identified; parous females were dissected and preparations of thorax content containing salivary glands were prepared. Remnants of the dissected midges were screened using PCR-based methods. Only thorax preparations of PCR-positive biting midges were examined microscopically. RESULTS: In total, 460 parous females belonging to 15 species were collected and dissected. DNA of haemosporidians was detected in 32 (7%) of dissected insects belonging to 7 species. Of the thorax samples PCR-positive for Haemoproteus parasites, two preparations were microscopically positive for sporozoites. Both biting midges were Culicoides kibunensis. Haemoproteus pallidus (hPFC1) was identified, indicating that transmission of this infection occurs at the study site. It was proved that seven species of biting midges take bird blood meals naturally in the wild. CONCLUSIONS: Culicoides kibunensis is a new vector species of avian haemoproteids and is a natural vector of H. pallidus. Numerous studies have identified vectors of Haemoproteus parasites experimentally; however, this is the first direct identification of a natural vector of Haemoproteus infection in the Old World. We suggest using the described methodology for vector research of Haemoproteus and other haemosporidians in the wild.

Severe chest allodynia as an unusual first presentation of hydatid disease: a case report.

BACKGROUND: Cystic echinococcosis (CE) is a worldwide zoonosis and the liver is the most commonly affected organ. Clinical manifestations range from completely asymptomatic cysts to a potential lethal cyst rupture and anaphylaxis. CASE PRESENTATION: Severe chest allodynia was an unusual clinical presentation of hepatic cyst rupture in the retroperitoneal space, without any other specific symptoms. CE diagnosis was confirmed by computed tomography scan and magnetic resonance. The patient underwent hepatectomy with complete resolution of the neuropathic pain. CONCLUSIONS: Retroperitoneal hydatid cyst rupture is a rare event and its clinical manifestation may mimic other chest neuropathies.

[Hydatid cysts of the liver ruptured into the thorax (about five cases)]. / Kystes hydatiques du foie rompus dans le thorax (à propos de cinq cas).

INTRODUCTION: Hydatid cyst of the liver remains a serious public health problem in Tunisia. This benign affection can sometimes cause fatal complications such as cyst rupture into the thorax. CLINICAL CASES: We report 5 cases of patients who experienced intrathoracic rupture of hydatic cyst of liver. There were four rural women and an urban man. Patients were between 60 and 75 years of age. We present 2 cases of cyst rupture into pleura, 3 cases of hydatid bronchial fistula and 3 cases of biliothoracic fistulas. Surgical treatment was performed by laparotomy in 3 cases, thoracic approach in one case and by thoracoabdominal approach in the other case. We deplore one case of early death by hemorrhagic shock. CONCLUSION: Authors emphasize the complexity of the management of hydatic cyst of liver ruptured into the thorax. Surgical treatment remains responsible of high perioperative morbidity and mortality. Early diagnostic and improvement of reanimation measures are important to improve the prognosis of this serious complication.

A Rare Human Case of Dirofilaria repens Infection in the Subcutaneous Posterior Thorax with Molecular Identification.

The emergence of Dirofilarial infections in Asia including Vietnam is a clinically significant threat to the community. We here report a rare case of subcutaneous Dirofilaria repens infection on the posterior thoracic wall in a young woman presenting a painful, itchy, and palpable nodule. The adult worm was identified by mitochondrial cox1 and nuclear ITS-2 sequence determination. The diagnosis was additionally confirmed by 16S rRNA sequencing of the endosymbiont Wolbachia pipientis commonly co-existing with D. repens. This is a rare case of subcutaneous human infection on the posterior thoracic region caused by D. repens.

Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galápagos Islands.

Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galápagos Islands, having colonised the archipelago around 200,000 years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood-meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A. taeniorhynchus in the Galápagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A. taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample was observed in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galápagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites of the genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galápagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A. taeniorhynchus may have facilitated a recent breakdown in host-species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galápagos Islands.

False positive circumsporozoite protein ELISA: a challenge for the estimation of the entomological inoculation rate of malaria and for vector incrimination.

BACKGROUND: The entomological inoculation rate (EIR) is an important indicator in estimating malaria transmission and the impact of vector control. To assess the EIR, the enzyme-linked immunosorbent assay (ELISA) to detect the circumsporozoite protein (CSP) is increasingly used. However, several studies have reported false positive results in this ELISA. The false positive results could lead to an overestimation of the EIR. The aim of present study was to estimate the level of false positivity among different anopheline species in Cambodia and Vietnam and to check for the presence of other parasites that might interact with the anti-CSP monoclonal antibodies. METHODS: Mosquitoes collected in Cambodia and Vietnam were identified and tested for the presence of sporozoites in head and thorax by using CSP-ELISA. ELISA positive samples were confirmed by a Plasmodium specific PCR. False positive mosquitoes were checked by PCR for the presence of parasites belonging to the Haemosporidia, Trypanosomatidae, Piroplasmida, and Haemogregarines. The heat-stability and the presence of the cross-reacting antigen in the abdomen of the mosquitoes were also checked. RESULTS: Specimens (N=16,160) of seven anopheline species were tested by CSP-ELISA for Plasmodium falciparum and Plasmodium vivax (Pv210 and Pv247). Two new vector species were identified for the region: Anopheles pampanai (P. vivax) and Anopheles barbirostris (Plasmodium malariae). In 88% (155/176) of the mosquitoes found positive with the P. falciparum CSP-ELISA, the presence of Plasmodium sporozoites could not be confirmed by PCR. This percentage was much lower (28% or 5/18) for P. vivax CSP-ELISAs. False positive CSP-ELISA results were associated with zoophilic mosquito species. None of the targeted parasites could be detected in these CSP-ELISA false positive mosquitoes. The ELISA reacting antigen of P. falciparum was heat-stable in CSP-ELISA true positive specimens, but not in the false positives. The heat-unstable cross-reacting antigen is mainly present in head and thorax and almost absent in the abdomens (4 out of 147) of the false positive specimens. CONCLUSION: The CSP-ELISA can considerably overestimate the EIR, particularly for P. falciparum and for zoophilic species. The heat-unstable cross-reacting antigen in false positives remains unknown. Therefore it is highly recommended to confirm all positive CSP-ELISA results, either by re-analysing the heated ELISA lysate (100 °C, 10 min), or by performing Plasmodium specific PCR followed if possible by sequencing of the amplicons for Plasmodium species determination.

[Splenic-thoracic transit: a rare evolution of hydatid disease]. / Transito esplenotorácico: una rara evoución de la hidatidosis.

We report a case of splenic hydatid cyst, an unfrequent localization of hydatid disease that usually presents with hydatid cysts in other organs (but not in this case). Primary spleen infestation generally occurs trough arterial blood supply, after the oncosphere of Echinococcus granulosus travels from host's digestive tube to the left atrium, passing trhough hepatic and pulmonar filters; other routes are also possible. Migration of an abdominal hydatid cyst into the thoracic cavity (phenomena called abdominal thoracic hydatid transit) occurs in 3.5% to 5% of liver cysts, and is quite exceptional in splenic cysts. Clinical manifestations are mainly thoracic, the diagnosis is based on serological tests and imaging studies, and surgical treatment is always required. Taking advantage of this unusual case, we remember the pathogenesis of splenic hydatid disease as well as the pathophysiology of transdiaphragmatic transit of abdominal hydatid disease.

Malaria vector surveillance in Ganghwa-do, a malaria-endemic area in the Republic of Korea.

We investigated the seasonality of Anopheles mosquitoes, including its species composition, density, parity, and population densities of mosquitoes infected with the parasite in Ganghwa-do (Island), a vivax malaria endemic area in the Republic of Korea. Mosquitoes were collected periodically with a dry-ice-tent trap and a blacklight trap during the mosquito season (April-October) in 2008. Anopheles sinensis (94.9%) was the most abundant species collected, followed by Anopheles belenrae (3.8%), Anopheles pullus (1.2%), and Anopheles lesteri (0.1%). Hibernating Anopheles mosquitoes were also collected from December 2007 to March 2008. An. pullus (72.1%) was the most frequently collected, followed by An. sinensis (18.4%) and An. belenrae (9.5%). The composition of Anopheles species differed between the mosquito season and hibernation seasons. The parous rate fluctuated from 0% to 92.9%, and the highest rate was recorded on 10 September 2008. Sporozoite infections were detected by PCR in the head and thorax of female Anopheles mosquitoes. The annual sporozoite rate of mosquitoes was 0.11% (2 of 1,845 mosquitoes). The 2 mosquitoes that tested positive for sporozoites were An. sinensis. Malarial infections in anopheline mosquitoes from a population pool were also tried irrespective of the mosquito species. Nine of 2,331 pools of Anopheles mosquitoes were positive. From our study, it can be concluded that An. sinensis, which was the predominant vector species and confirmed as sporozoite-infected, plays an important role in malaria transmission in Ganghwa-do.

Hydatid hepatic cysts rupture into the biliary tract, the peritoneal cavity, the thoracic cavity and the hepatic subcapsular space: specific computed tomography findings.

BACKGROUND: This study attempts to demonstrate the role of computed tomography in the diagnosis of hepatic hydatid cyst rupture based on specific imaging findings and to propose combinations of the imaging findings diagnostic for specific types of rupture. METHODS: Eleven patients were studied with computed tomography of the abdomen, with 4-8 mm slice thickness, after the oral administration of contrast material and intravenous contrast material in 6 cases. RESULTS: Based on a combination of imaging findings the types of hepatic hydatid cyst rupture were: intrabiliary rupture in 7 patients, intraperitoneal rupture in 1 patient, intrathoracic rupture in 1 patient, hepatic subcapsular rupture in 2 patients. Structural deformity of the cyst was present in all cases, combined with: dilatation of the intrahepatic bile ducts (intrabiliary rupture); intraperitoneal fluid collections with diffuse haziness and stranding of the mesenteric fat (intraperitoneal rupture); an inhomogeneous lesion in the thorax with ipsilateral pleural effusion (intrathoracic rupture); a hydatid cyst located peripherally, with discontinuity of its adjacent to the hepatic capsule wall and subcapsular fluid collection (subcapsular rupture). The imaging findings were surgically and pathologically confirmed. CONCLUSIONS: Using combinations of specific imaging findings we correctly diagnosed the type of hepatic hydatid cyst rupture in all cases.

Unusual radiologic manifestations of the echinococcus infection in the thorax.

Unusual location and presentation of hydatid cyst disease in the thorax requires careful consideration with respect to clinical approach and therapy. In this pictorial essay, we present imaging findings and describe treatment of thoracic hydatid cysts in patients with lung, mediastinal, chest wall, cardiac, endobronchial, pulmonary artery, and diaphragmatic involvement. A review of the literature is also included.

Culex quinquefasciatus in Phitsanulok as a possible vector of nocturnally periodic Wuchereria bancrofti transmission in Myanmar immigrants.

The present study was undertaken in order to study whether Culex quinquefasciatus collected in Phitsanulok Province can be an insect host for the development of Wuchereria bancrofti larvae. W. bancrofti infected blood from Myanmar workers in Mae Sot, Tak Province was fed to mosquitoes by using the artificial membrane feeding. An infection of W. bancrofti was found with the highest density of L3 in the mosquito thorax on the 14th day after feeding. The infection rate also correlated to the density of microfilaria found in the donor's blood. Our results showed that Cx. quinquefasciatus in Phitsanulok is a possible vector of nocturnally periodic W. bancrofti.

First record of metacestodes of Mesocestoides sp. in the common starling (Sturnus vulgaris) in Europe, with an 18S rDNA characterisation of the isolate.

Metacestodes of Mesocestoides sp. were recorded from Sturnus vulgaris (Passeriformes: Stumidae) in the Czech Republic in April 2002. They were found in a cutaneous cyst and in the thoracic region of the body cavity of the bird. This is the first record of metacestodes of Mesocestoides sp. in this host species in Europe as well as the first finding of the formation of a cutaneous cyst provoked by this parasite. Additional specimens from Apodemus agrarius (Mammalia: Rodentia) from Bulgaria and Lacerta agilis (Reptilia: Squamata) from the Czech Republic were compared with that from S. vulgaris. Sequence data from the V4 variable region (18S rDNA) were used to compare genetic variability among these and previously characterized isolates of Mesocestoides spp. A number of distinct clades were recognized, with metacestodes from L. agilis showing the highest degree of relative divergence.