Vector-borne Infections Research Articles

Increased risk for autochthonous vector-borne infections transmitted by Aedes albopictus in continental Europe.

Autochthonous outbreaks of chikungunya and dengue during the past decade showed that continental Europe is vulnerable to Aedes albopictus–borne infections. Ae. albopictus has spread geographically, resulting in more people exposed to risk. Timely application of adequate mosquito suppression measures may delay, or even prevent, the vector population from crossing the potential epidemic abundance threshold should a pathogen be introduced. Health authorities should be on alert to detect early cases to prevent autochthonous outbreaks.

Identification of White-tailed Deer (Odocoileus virginianus) as a Novel Reservoir Species forTrypanosoma cruziin Texas, USA

Chagas disease, a vector-borne parasitic infection caused by Trypanosoma cruzi, represents a significant source of morbidity and mortality in the Americas. Mammalian reservoir species play a large role in propagating the sylvatic transmission cycle of this disease, and this cycle can spill over, resulting in human infections. Our understanding of the wildlife species implicated in propagating this transmission cycle is incomplete. We investigated white-tailed deer ( Odocoileus virginianus) as a potential novel reservoir for this parasite. Only one of the 314 hunter-harvested deer hearts collected across Texas, was PCR-positive (0.3%) for T. cruzi. This finding has potential implications for deer hunters, because it indicates that there might be a risk of blood-borne transmission during the field-dressing process. Hunters should be strongly encouraged to wear gloves and other personal protective equipment when handling carcasses to prevent exposure to infected blood.

Experience of GIS Technology Application in the Surveillance of Tick-Borne Infections

ObjectiveThe main aim of this work is to estimate the projected risks based on the incidence rate of natural foci infections and to expand the list of criteria for the characterization of natural foci of tick-borne infections.IntroductionThe epidemiological situation of natural foci of tick-borne infections (TBI) in Ukraine, as well as globally, is characterized by significant activation of processes due to global climate change, growing human-induced factor and shortcomings in the organization and running of epidemiological surveillance [1]. For the Western region of Ukraine, among all tick-borne zoonoses the most important are tick-borne viral encephalitis (TBVE), Lyme disease (LD), human granulocytic anaplasmosis (HGA) and some others [2-4]. Taking into account the increased incidence rate for these infections, we have developed baseline criteria (indicators of natural contamination of the main carriers and levels of the serum layer among the population in relation to the TBI pathogens in the endemic areas) to identify areas with different risk of contamination through GIS-technologies [5].MethodsEpi Info 7.1.1.14 software was used to analyze patient questionnaires with tick-borne infections (TBI) for 2010-2015. Prevalence maps of vector-borne infections were created by means of GIS technology using the QGIS 2.0.1. software to assess the risks of infection. Maps demonstrating the distribution of TBVE, LD and HGA were also developed based on contamination risk assessment criteria.ResultsRetrospective epidemiological analysis of incidence rates for TBVE, LD and HGA was conducted based on laboratory tests that were performed in the laboratory of vector-borne viral infections of the State Institution Lviv Research Institute of Epidemiology and Hygiene of the Ministry of Health of Ukraine. A direct correlation between the infection of I. ricinus, B. burgdorferi and LB (P <0.05) and infections of I. ricinus ticks, anaplasma and incidence of HGA (P <0.05) was established. However, this connection has not been confirmed for indicators with TBE.Data was obtained during the assessment of possible risks of tick-borne infections. For TBVE, the indicator of predicted risks based on the basic criteria was 60.3%, taking into account the cases of the disease. This was based on indicators of natural infection of the main carriers and the level of the serum layer among the population on the TBI activators in the endemic areas. The data obtained can be explained by the low level of morbidity and the detection of TBVE cases. The predicted risk for LD according to these criteria is 88.9%, due to the high level of clinical and laboratory diagnosis.As for the HGA, the predicted risk indicator reaches 66.7% due to the fact that the study of human anaplasmosis in Ukraine is at the initial level (the incidence rate and incidence are not included in the official reporting system).Taking into account the results obtained, it is advisable to supplement the list of criteria for determining the degree of activity of natural foci of tick-borne infections and the identification of areas with high risk of morbidity. These calculations were made by grouping statistical data (indicators) [5]. The reliability of the difference between the same indicators for individual zones was 95% (Table 1).ConclusionsTick-borne zoonoses are a serious problem for the public health system of the Western region of Ukraine. Extending the list of criteria for the characterization of natural foci of tick-borne infections will improve epidemiological surveillance and focus on key measures in high and medium-risk areas for the rational use of funds.

Morbidity management and disability prevention for lymphatic filariasis in Sri Lanka: Current status and future prospects.

BackgroundSri Lanka was acknowledged to have eliminated lymphatic filariasis (LF) as a public health problem in 2016, largely due to its success in Mass Drug Administration (MDA) to interrupt disease transmission. Analysis of the Strengths, Weaknesses, Opportunities and Threats (SWOT) of the national Morbidity Management and Disability Prevention (MMDP) program, the other pillar of the LF control program, was carried out with the objective of evaluating it and providing recommendations to optimize the use of available resources.MethodologyA situation analysis of the MMDP activities provided by the state health sector was carried out using published records, in-depth interviews with key informants of the Anti Filariasis Campaign, site-visits to filariasis clinics with informal discussions with clinic workforce and personal communications to identify strengths and weaknesses; and opportunities to overcome weaknesses and perceived threats to the program were explored.The principal strength of the MMDP program was the filariasis clinics operational in most endemic districts of Sri Lanka, providing free health care and health education to clinic attendees. The weaknesses identified were the low accessibility of clinics, incomplete coverage of the endemic region and lack of facilities for rehabilitation. The perceived threats were diversion of staff and resources for control of other vector-borne infections, under-utilization of clinics and non-compliance with recommended treatment. Enhanced high level commitment for MMDP, wider publicity and referral systems, integration of MMDP with other disease management services and collaboration with welfare organizations and research groups were identified as opportunities to overcome weaknesses and challenges.ConclusionsThe recommended basic package of MMDP was functional in most of the LF-endemic region. The highlighted weaknesses and challenges, unless addressed, may threaten program sustainability. The identified opportunities for improvement of the programme could ensure better attainment of the goal of the MMDP program, namely access to basic care for all affected by lymphatic filarial disease.

Borrelia burgdorferi adhere to blood vessels in the dura mater and are associated with increased meningeal T cells during murine disseminated borreliosis.

Borrelia burgdorferi, the causative agent of Lyme disease, is a vector-borne bacterial infection that is transmitted through the bite of an infected tick. If not treated with antibiotics during the early stages of infection, disseminated infection can spread to the central nervous system (CNS). In non-human primates (NHPs) it has been demonstrated that the leptomeninges are among the tissues colonized by B. burgdorferi spirochetes. Although the NHP model parallels aspects of human borreliosis, a small rodent model would be ideal to study the trafficking of spirochetes and immune cells into the CNS. Here we show that during early and late disseminated infection, B. burgdorferi infects the meninges of intradermally infected mice, and is associated with concurrent increases in meningeal T cells. We found that the dura mater was consistently culture positive for spirochetes in transcardially perfused mice, independent of the strain of B. burgdorferi used. Within the dura mater, spirochetes were preferentially located in vascular regions, but were also present in perivascular, and extravascular regions, as late as 75 days post-infection. At the same end-point, we observed significant increases in the number of CD3+ T cells within the pia and dura mater, as compared to controls. Flow cytometric analysis of leukocytes isolated from the dura mater revealed that CD3+ cell populations were comprised of both CD4 and CD8 T cells. Overall, our data demonstrate that similarly to infection in peripheral tissues, spirochetes adhere to the dura mater during disseminated infection, and are associated with increases in the number of meningeal T cells. Collectively, our results demonstrate that there are aspects of B. burgdorferi meningeal infection that can be modelled in laboratory mice, suggesting that mice may be useful for elucidating mechanisms of meningeal pathogenesis by B. burgdorferi.

Using Landscape Analysis to Test Hypotheses about Drivers of Tick Abundance and Infection Prevalence with Borrelia burgdorferi.

Patterns of vector-borne disease risk are changing globally in space and time and elevated disease risk of vector-borne infection can be driven by anthropogenic modification of the environment. Incidence of Lyme disease, caused by the bacterium Borrelia burgdorferi sensu stricto, has risen in a number of locations in North America and this increase may be driven by spatially or numerically expanding populations of the primary tick vector, Ixodes scapularis. We used a model selection approach to identify habitat fragmentation and land-use/land cover variables to test the hypothesis that the amount and configuration of forest cover at spatial scales relevant to deer, the primary hosts of adult ticks, would be the predominant determinants of tick abundance. We expected that land cover heterogeneity and amount of forest edge, a habitat thought to facilitate deer foraging and survival, would be the strongest driver of tick density and that larger spatial scales (5–10 km) would be more important than smaller scales (1 km). We generated metrics of deciduous and mixed forest fragmentation using Fragstats 4.4 implemented in ArcMap 10.3 and found, after adjusting for multicollinearity, that total forest edge within a 5 km buffer had a significant negative effect on tick density and that the proportion of forested land cover within a 10 km buffer was positively associated with density of I. scapularis nymphs. None of the 1 km fragmentation metrics were found to significantly improve the fit of the model. Elevation, previously associated with increased density of I. scapularis nymphs in Virginia, while significantly predictive in univariate analysis, was not an important driver of nymph density relative to fragmentation metrics. Our results suggest that amount of forest cover (i.e., lack of fragmentation) is the most important driver of I. scapularis density in our study system.

Clinical evaluation of outdoor cats exposed to ectoparasites and associated risk for vector-borne infections in southern Italy

BackgroundCats can be carriers of infected arthropods and be infected with several vector-borne pathogens (VBP) but there is limited knowledge about their pathogenic role in cats.ResultsA cross-sectional controlled study investigated the clinical status and antibody (Bartonella henselae, Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum, Babesia microti and Leishmania infantum) and/or blood PCR (Mycoplasma spp., Bartonella spp., Rickettsia spp., Ehrlichia/Anaplasma spp., piroplasmids, L. infantum, Hepatozoon felis) prevalence in 197 cats. Outdoor cats lacking ectoparasiticide treatment or hosting ectoparasites (study group [SG], n = 134) and indoor cats treated against ectoparasites (control group [CG], n = 63) were enrolled. Clinical data and retroviral co-infections were compared between the two groups. Multivariable analysis tested associations between variables and VBP exposure. Lymphadenia, stomatitis, and various haematological abnormalities were statistically more frequent in SG. Antibodies against R. conorii, B. henselae, A. phagocytophylum, B. microti, E. canis and L. infantum were detected. Bartonella henselae, Bartonella clarridgeiae, Mycoplasma haemofelis, “Candidatus Mycoplasma haemominutum” and “Candidatus Mycoplasma turicensis” DNA were identified. Very high antibody (87.8%) and PCR (40.1%) positivity to at least one pathogen were detected and were significantly higher in SG. Co-infections were confirmed in about one-third of the cats and were more frequent in SG cats. Molecular and overall (antibody and PCR) positivity to Bartonella and antibody positivity to R. conorii were higher in SG. Multivariable analysis found significant associations of Bartonella spp. infection with Feline Immunodeficiency Virus (FIV) infection and increased globulins, and of Mycoplasma spp. infection with adult age, FIV infection, anaemia, and increased creatinine.ConclusionsA very high prevalence of exposure to zoonotic VBP was found in cats, with Rickettsia and Bartonella infections being most prevalent. Some risk factors were documented namely for Mycoplasma spp. and Bartonella spp. The lifestyle of cats is clinically relevant and requires specific preventative measures to protect their health.

Cutaneous Leishmaniasis in the Metropolitan City of Multan, Pakistan, a Neglected Tropical Disease

Cutaneous leishmaniasis is a vector-borne infection caused by flagellated parasitic protozoans in the genus Leishmania. Promastigotes are the infective stage, which are transmitted by the bite of female sand flies of the genera Phlebotomus or Lutzomyia. Three clinical forms of Leishmania infection are recognized in humans, and they are caused by different Leishmania species. They are cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (ML), and visceral leishmaniasis (VL). Up to 2 million cases of leishmaniasis are reported annually worldwide. In Pakistan, CL is widely distributed in endemic areas. In the current study, a survey was conducted to investigate the occurrence of CL in an endemic area of the metropolitan city of Multan, Pakistan. The material for diagnosis of CL was obtained from 461 patients from 239 clinical laboratories and health care centers in Multan. Of these patients, 42.9% (198 of 461) having positive findings of amastigotes in Giemsa stained tissue impression smears. The distribution of CL skin lesions was highly variable. Most patients (76.2%) had a single lesion. Most CL lesions were found on a single hand (23.7%). The prevalence of two CL lesions per patient was 21.7%, while three or more positive CL lesions were observed in 2.0% of patients. The 198 CL-positive patients ranged in age 10-40 yr old, 101 were males, and 97 were females. Logistic regression analysis of leishmaniasis versus age and gender showed that both the age and gender had a significant (P < 0.05) effect on the occurrence of infection. Outbreaks of CL were reported in 14 of the 68 Union Councils of Multan.

Models of Disease Vector Control: When Can Aggressive Initial Intervention Lower Long-Term Cost?

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. As vectors may invade both from other infested houses and sylvatic areas and as the effectiveness of insecticide wears off over time, the dynamics of (re)infestations can be approximated by [Formula: see text]-type models with a reservoir, where housing units are treated as hosts, and insecticide spraying corresponds to removal of hosts. Here, we investigate three ODE-based models of this type. We describe a dual-rate effect where an initially very high spraying rate can push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels. We determine some sufficient and some necessary conditions under which this effect occurs and show that it is robust in models that incorporate some heterogeneity in the relevant properties of housing units.

Detecting the Lyme Disease Spirochete, Borrelia Burgdorferi, in Ticks Using Nested PCR.

Lyme disease is a serious vector-borne infection that is caused by the Borrelia burgdorferi sensu lato family of spirochetes, which are transmitted to humans through the bite of infected Ixodes ticks. The primary etiological agent in North America is Borrelia burgdorferi sensu stricto. As geographic risk regions expand, it is prudent to support robust surveillance programs that can measure tick infection rates, and communicate findings to clinicians, veterinarians, and the general public. The molecular technique of nested polymerase chain reaction (nPCR) has long been used for this purpose, and it remains a central, inexpensive, and robust approach in the detection of Borrelia in both ticks and wildlife. This article demonstrates the application of nPCR to tick DNA extracts to identify infected specimens. Two independent B. burgdorferi targets, genes encoding Flagellin B (FlaB) and Outer surface protein A (OspA), have been used extensively with this technique. The protocol involves tick collection, DNA extraction, and then an initial round of PCR to detect each of the two Borrelia-specific loci. Subsequent polymerase chain reaction (PCR) uses the product of the first reaction as a new template to generate smaller, internal amplification fragments. The nested approach improves upon both the specificity and sensitivity of conventional PCR. A tick is considered positive for the pathogen when inner amplicons from both Borrelia genes can be detected by agarose gel electrophoresis.

Detecting the Lyme Disease Spirochete, &lt;em&gt;Borrelia Burgdorferi&lt;/em&gt;, in Ticks Using Nested PCR

Lyme disease is a serious vector-borne infection that is caused by the Borrelia burgdorferi sensu lato family of spirochetes, which are transmitted to humans through the bite of infected Ixodes ticks. The primary etiological agent in North America is Borrelia burgdorferi sensu stricto. As geographic risk regions expand, it is prudent to support robust surveillance programs that can measure tick infection rates, and communicate findings to clinicians, veterinarians, and the general public. The molecular technique of nested polymerase chain reaction (nPCR) has long been used for this purpose, and it remains a central, inexpensive, and robust approach in the detection of Borrelia in both ticks and wildlife. This article demonstrates the application of nPCR to tick DNA extracts to identify infected specimens. Two independent B. burgdorferi targets, genes encoding Flagellin B (FlaB) and Outer surface protein A (OspA), have been used extensively with this technique. The protocol involves tick collection, DNA extraction, and then an initial round of PCR to detect each of the two Borrelia-specific loci. Subsequent polymerase chain reaction (PCR) uses the product of the first reaction as a new template to generate smaller, internal amplification fragments. The nested approach improves upon both the specificity and sensitivity of conventional PCR. A tick is considered positive for the pathogen when inner amplicons from both Borrelia genes can be detected by agarose gel electrophoresis.

The Canary Islands as a model of risk of pulmonary dirofilariasis in a hyperendemic area.

We assessed the risk of human pulmonary dirofilariasis in the Canary Islands, hyperendemic for canine heartworm (Dirofilaria immitis), a zoonotic vector-borne infection. For this purpose, 1479 inhabitants were tested for anti-D. immitis antibodies. Four of the 7 islands presented high seroprevalences (from 6.2 to 12.7%), therefore high exposure to the parasite and risk of zoonotic infection. These corresponded to those islands with high canine prevalences of dirofilariasis and favourable climatic conditions for the development of mosquito vectors. The lowest prevalences (from 0 to 1.6%) were found in the desert islands and those with low canine prevalences of heartworm. Seroprevalences were very variable inside each island as well, being related to the climate and demographic factors. Human pulmonary dirofilariasis is an emerging zoonosis worldwide which frequently goes undiagnosed. Serological studies could be useful for the correct evaluation of the risk of infection among the human population, and study of the health implications of the continuous contact with the parasite in endemic areas. Sanitary authorities should be aware of the current epidemiological data, and physicians should include human dirofilariasis in the differential diagnosis of pulmonary nodules.

PCR evaluation of selected vector-borne pathogens in dogs with pericardial effusion.

To investigate evidence for selected vector-borne pathogen infections in dogs with pericardial effusion living in a Mediterranean area in which several canine vector-borne diseases are endemic. Archived EDTA blood (n=68) and pericardial fluid samples (n=58) from dogs with pericardial effusion (n=68) were included. Dogs without pericardial effusion examined for other reasons were included as controls (n=60). Pericardial effusion was classified as neoplastic in 40 dogs, idiopathic in 23 dogs and of unknown aetiology in 5 dogs. Real-time PCR was performed for Leishmania infantum, Ehrlichia/Anaplasma species, Hepatozoon canis, Babesia species, Rickettsia species and Bartonella species, and sequencing of PCR products from positive samples was used to confirm species specificity. Vector-borne pathogens were found in 18 dogs: 16 of 68 dogs with pericardial effusion (23·5%) and two of 60 control dogs (3·3%). Positive dogs demonstrated DNA of Leishmania infantum (n=7), Anaplasma platys (n=2, one dog coinfected with Leishmania infantum), Babesia canis (n=5), Babesia gibsoni (n=3) and Hepatozoon canis (n=2). Vector-borne pathogens were more commonly detected among dogs with pericardial effusion than controls (P=0·001). There was no relationship between aetiology of the pericardial effusion and evidence of vector-borne pathogens (P=0·932). Vector-borne pathogens are often detected in dogs with pericardial effusion and require further investigation, especially in dogs with idiopathic pericardial effusion. PCR can provide additional information about the potential role of vector-borne pathogens in dogs with pericardial effusion living in endemic areas.

The rise of neglected tropical diseases in the "new Texas".

Within the last five years, the State of Texas has experienced either transmission or outbreaks of Ebola, chikungunya, West Nile, and Zika virus infections. Autochthonous transmission of neglected parasitic and bacterial diseases has also become increasingly reported. The rise of such emerging and neglected tropical diseases (NTDs) has not occurred by accident but instead reflects rapidly evolving changes and shifts in a “new” Texas beset by modern and globalizing forces that include rapid expansions in population together with urbanization and human migrations, altered transportation patterns, climate change, steeply declining vaccination rates, and a new paradigm of poverty known as “blue marble health.” Summarized here are the major NTDs now affecting Texas. In addition to the vector-borne viral diseases highlighted above, there also is a high level of parasitic infections, including Chagas disease, trichomoniasis, and possibly leishmaniasis and toxocariasis, as well as typhus-group rickettsiosis, a vector-borne bacterial infection. I also highlight some of the key shifts in emerging and neglected disease patterns, partly due to an altered and evolving economic and ecological landscape in the new Texas, and provide some preliminary disease burden estimates for the major prevalent and incident NTDs.

Self-reported Animal and Ectoparasite Exposure among Urban Homeless People.

Homeless people in the United States may experience poor hygiene and spend extended periods of time outdoors, which increases exposure to animal and insect vectors of disease. Despite these risks, efforts to understand frequency and risk factors for zoonotic and vector-borne infections among homeless people have been limited. We queried homeless people in Boston, Massachusetts (n=194) to evaluate exposure to urban wildlife and ectoparasites associated with infection. Thirty percent of participants reported seeing rodents daily, and 25% reported daily sightings of cats. Body lice and fleas were reported by 4% and 11% of participants, respectively. Sleeping outdoors and heavy drinking were positively associated with rodent and ectoparasite exposure. Frequent sightings of rodents and rodent feces among homeless people in particular areas may indicate human exposure risk to urban rodent-borne pathogens, including Leptospira spp, Seoul hantavirus, and Rickettsia akari. Epidemiologic studies of zoonotic and vector-borne infections in this population are warranted.

Potential anti-flavivirus herbals: A better and safer heath alternatives

Flaviviral infections are increasing at an alarming rate creating a global health concern. As a result, targeted and focused research for developing suitable diagnostics and therapeutics against the re-emergent infection have become the need of the hour. The targeted search of natural antiviral measures surged, as such ancient practices have been used to treat different vector borne infections like malaria, Japanese encephalitis, and dengue. Antivirals can serve to be safer, cheaper and more importantly non-toxic than the chemical alternatives. This article encompasses and elucidate the potential antiflaviviral activities of herbals (medicinal plants), which are geographically distributed around the world, and have significant potential to be used or are being screened to treat similar existent infections. Medicinal plants under trials for their antiflaviviral properties are also covered in this review. Ongoing studies suggest that medicinal plants can be a rich source for flaviviral combating compounds but further more investigations are needed to establish the potentiality of these medicinal herbs for new emergent flavivirus infection control. Enormous scope is available in these herbals, which can result in bringing out viable alternatives and long term resistance against the emerging and re-emerging flaviviral diseases.

Metal- and metalloid-containing drugs for the treatment of trypanosomatid diseases.

The trypanosomatid-induced diseases are considered as neglected, because the countries where they kill people are not important markets for western big pharmaceutical companies. However, recently some effort has been made to translate the use of already known drugs to neglected infectious disease. Although many metals are essential to life, many disorders affecting metal homeostasis and bioavailability are responsible for several human diseases. Metals can be toxic even at very low concentrations and semimetals are classified as toxic and dangerous for the environment. However, metal- and metalloid-based therapeutic drugs have existed for centuries. Some of them, as antimony and arsenic compounds, are still the first line drugs used for the treatment of leishmaniasis and trypanosomiases in developing countries. Other metal complexes (as those of Ag, Pt, Pd and Au), already present in the market for cancer therapies or to cure bacterial infection or for anti-inflammatory treatments, have been proposed also against the vector-borne infections caused by trypanosomatids. The use of novel approaches based on nanotechnologies, allowing selective targeting, may represent a promising strategy to decrease the toxicity of these drugs.

An update on benznidazole for the treatment of patients with Chagas disease.

Chagas disease is a vector-borne, systemic and chronic parasitic infection caused by Trypanosoma cruzi with approximately 8 million cases worldwide. The treatment for acute phase of Chagas disease consists of benznidazole and nifurtimox, although this treatment combination falls short in terms of efficacy against chronic phases of infection. This review provides an update on benznidazole progress and approval by the U.S. Food and Drug Administration in 2017 for the treatment of Chagas disease along with its lacunae.

Illness among US resident student travellers after return to the USA: a GeoSentinel analysis, 2007-17.

The number of US students studying abroad more than tripled during the past 20 years. As study abroad programmes' destinations diversify, students increasingly travel to resource-limited countries, placing them at risk for infectious diseases. Data describing infections acquired by US students while travelling internationally are limited. We describe illnesses among students who returned from international travel and suggest how to prevent illness among these travellers. GeoSentinel is a global surveillance network of travel and tropical medicine providers that monitors travel-related morbidity. This study included the records of US resident student international travellers, 17-24 years old, who returned to the USA, had a confirmed travel-related illness at one of 15 US GeoSentinel sites during 2007-17 and had a documented exposure region. Records were analysed to describe demographic and travel characteristics and diagnoses. The study included 432 students. The median age was 21 years; 69% were female. More than 70% had a pre-travel consultation with a healthcare provider. The most common exposure region was sub-Saharan Africa (112; 26%). Students were most commonly exposed in India (44; 11%), Ecuador (28; 7%), Ghana (25; 6%) and China (24; 6%). The median duration of travel abroad was 40 days (range: 1-469) and presented to a GeoSentinel site a median of 8 days (range: 0-181) after travel; 98% were outpatients. Of 581 confirmed diagnoses, the most common diagnosis category was gastrointestinal (45%). Acute diarrhoea was the most common gastrointestinal diagnosis (113 of 261; 43%). Thirty-one (7%) students had vector-borne diseases [14 (41%) malaria and 11 (32%) dengue]. Three had vaccine-preventable diseases (two typhoid; one hepatitis A); two had acute human immunodeficiency virus infection. Students experienced travel-related infections, despite the majority having a pre-travel consultation. US students should receive pre-travel advice, vaccinations and chemoprophylaxis to prevent gastrointestinal, vector-borne, sexually transmitted and vaccine-preventable infections.

Laboratory diagnosis of human infections transmitted by ticks, fleas, mites and lice in Australia

A wide range of human pathogens (viruses, bacteria, protozoa) are transmitted by ticks, fleas, mites and lice worldwide. Some of these infections occur in Australia1, whereas others appear to be absent, although they may occur in returned travellers. The key to diagnosis is two-fold: recognition of the possibility of a vector-borne infection by the treating doctor and confirmation of the diagnosis in a diagnostic, microbiology laboratory. Laboratory diagnostic assays include culture (used rarely), nucleic acid amplification (used increasingly) and serology (used often).