Incidence rate and risk factors for giardiasis and strongyloidiasis in returning UK travellers

Strongyloides stercoralis infection in the UK: A systematic review and meta-analysis of published cases

Strongyloidiasis is a helminth infection where symptoms vary, and asymptomatic presentation is common. Chronic strongyloidiasis can cause a high mortality 'hyper-infection' in immunocompromised states. Understanding at risk populations and symptomology can guide screening and early treatment to reduce hyper-infection risk. A systematic review of studies describing patients in the UK with strongyloidiasis pooled a total of 1,308 patients. Weighted pooled prevalence (WPP) of asymptomatic cases was 27.7% (95% CI 17.1-39.5%, I2 = 92%, p < 0.01). At-risk populations included migrants, returning travellers and armed forces personnel. The most common symptoms reported were abdominal pain (WPP 32.1% (95% CI 20.5-44.8%), I2 = 93%, p < 0.01), rashes (WPP 38.4% (95% CI 13.1-67.7%), I2 = 99%, p < 0.01) and diarrhoea (WPP 12.6% (95% CI 6.7-19.9%), I2=70%, p = 0.03). Symptomatology varied with cohort characteristics. Although asymptomatic presentation is common, patients may present with abdominal pain, diarrhoea or rashes. A low threshold for screening symptomatic individuals in at-risk groups is required.

Intestinal protozoa in returning travellers: a GeoSentinel analysis from 2007 to 2019

BACKGROUND

Prolonged diarrhoea is common amongst returning travellers and is often caused by intestinal protozoa. However, the epidemiology of travel-associated illness caused by protozoal pathogens is not well described.

METHODS

We analysed records of returning international travellers with illness caused by Giardia duodenalis, Cryptosporidium spp., Cyclospora cayetanensis or Cystoisospora belli, reported to the GeoSentinel Network during January 2007-December 2019. We excluded records of travellers migrating, with an unascertainable exposure country, or from GeoSentinel sites that were not located in high-income countries.

RESULTS

There were 2517 cases, 82.3% giardiasis (n = 2072), 11.4% cryptosporidiosis (n = 287), 6.0% cyclosporiasis (n = 150) and 0.3% cystoisosporiasis (n = 8). Overall, most travellers were tourists (64.4%) on long trips (median durations: 18-30 days). Cryptosporidiosis more frequently affected people < 18 years (13.9%) and cyclosporiasis affected people ≥ 40 years (59.4%). Giardiasis was most frequently acquired in South Central Asia (45.8%) and sub-Saharan Africa (22.6%), cryptosporidiosis in sub-Saharan Africa (24.7%) and South-Central Asia (19.5%), cyclosporiasis in South East Asia (31.3%) and Central America (27.3%), and cystoisosporiasis in sub-Saharan Africa (62.5%). Cyclosporiasis cases were reported from countries of uncertain endemicity (e.g. Cambodia) or in countries with no previous evidence of this parasite (e.g. French Guiana). The time from symptom onset to presentation at a GeoSentinel site was the longest amongst travellers with giardiasis (median: 30 days). Over 14% of travellers with cryptosporidiosis were hospitalized.

CONCLUSIONS

This analysis provides new insights into the epidemiology and clinical significance of four intestinal protozoa that can cause morbidity in international travellers. These data might help optimize pretravel advice and post-travel management of patients with travel-associated prolonged gastrointestinal illnesses. This analysis reinforces the importance of international travel-related surveillance to identify sentinel cases and areas where protozoal infections might be undetected or underreported.

Risk factors for and management of metronidazole-refractory giardiasis in international travellers: A retrospective analysis

BACKGROUND

Giardia lamblia is a common cause of diarrhoea in returning travellers. Failure of the recommended first-line treatment, metronidazole, has frequently been observed. Recommendations for treatment of metronidazole-refractory giardiasis lack clarity and evidence.

METHODS

We conducted a retrospective data analysis of returned travellers with confirmed giardiasis at the Bernhard-Nocht-Clinic in Hamburg, Germany, between 2007 and 2016.

RESULTS

We identified 339 cases of giardiasis, mostly acquired in South Asia (n = 157). 308 patients received metronidazole as first-line treatment, leading to treatment failure in 93 cases. Statistical analysis suggested by far the highest risk of metronidazole treatment failure for travellers returning from South Asia (Odds Ratio 8.73). Second-line therapy consisted of various different therapy regimens. Combination therapy as second-line treatment seemed to be more effective than monotherapy. A repeat course of metronidazole proved to be futile.

CONCLUSION

This study reveals a strikingly low effectiveness of metronidazole, especially in patients returning from South Asia. Second-line treatment showed inconsistency of regimens and yielded unsatisfactory results. These findings require reconsideration of treatment strategies for giardiasis. Large prospective trials are urgently needed to assess new first-line treatment options and to help implement advice for effective, agreed second-line treatment strategies. Translational projects should be created to link the understanding of resistance mechanisms with epidemiological data and clinical outcome.

Identifying human enteric parasitic infections in Greece, with focus on Giardia and Cryptosporidium

A study was conducted in two different areas in Greece to investigate the presence of intestinal human parasitic infections (targeting healthy and individuals with diarrhoea). In total, 876 stool samples were collected from 822 adults and 54 children. Both sedimentation (acid/ether) and concentration/flotation techniques were performed in all samples to detect intestinal parasites. Additionally, a quantitative direct immunofluorescence assay was used specifically for the detection of Giardia and Cryptosporidium. PCR followed by sequencing was applied to genotype Giardia and Cryptosporidium positive samples. Thirty-five (4%) of the individuals examined harboured at least one species of intestinal parasite, the majority of which were protozoa (3.8%). The species found were Blastocystis hominis (1.8%), Giardia duodenalis (1.3%), Cryptosporidium spp. (0.6%), Entamoeba coli (0.2%) and E. histolytica/E. dispar (0.1%). Two persons were positive for Enterobius vermicularis. Genotyping results revealed the presence of G. duodenalis sub-assemblage AII, whereas sequencing was not successful for Cryptosporidium positive samples. A novel multi-locus genotype of G. duodenalis was identified, which has not been described in humans or animals previously. Overall, in the studied population, infection rates with intestinal parasites were low and similar to previous published data. As infection levels were low, no associations could be made between infection status and clinical relevance, risk factors or indication of potential sources of infection, apart from the fact that infections with Giardia were positively correlated to diarrhoea. Based on the parasite species and genotypes detected, there was no indication that animals were an important source of infection. Thus, it is suggested that Giardia infections were more likely to be acquired via human-to-human transmission, either involving indirect pathways such as contaminated food or water, or via direct contact.

"Tear Drops in the Duodenum": Uncommon Cause of Iron Deficiency Anemia in Adults

A 64-year-old man presented to the internal medicine resident clinic with fatigue and abdominal pain of six-month duration. He did not have diarrhea, hematemesis, melena, or hematochezia. Physical examination was unremarkable. Laboratory findings were consistent with iron deficiency anemia. Upper and lower gastrointestinal (GI) endoscopies revealed normal findings. Duodenal biopsy showed trophozoites (tear-drop-shaped) morphologically consistent with Giardia duodenalis. He was prescribed metronidazole and iron replacement therapy, with a resultant improvement in symptoms as well as lab values at the four-month follow-up visit.

Ocular Parasitosis Caused by Protozoan Infection during Travel: Focus on Prevention and Treatment

International travel is rising quickly worldwide. Many people travel to tropical and subtropical areas, where there has been increasing exposure of travelers to infectious pathogens. Ocular parasitic infections are more prevalent in these geographical areas and they can lead to morbidity and mortality, often due to late or misdiagnosis due to the unfamiliarity of health staff with these diseases. This is an up-to-date comprehensive review article that familiarizes physicians with ocular signs and symptoms, treatment, prevention, and geographic distribution of some parasites associated with travel.

Is the Definition of Roma an Important Matter? The Parallel Application of Self and External Classification of Ethnicity in a Population-Based Health Interview Survey

The Roma population is typified by a poor and, due to difficulties in ethnicity assessment, poorly documented health status. We aimed to compare the usefulness of self-reporting and observer-reporting in Roma classification for surveys investigating differences between Roma and non-Roma populations. Both self-reporting and observer-reporting of Roma ethnicity were applied in a population-based health interview survey. A questionnaire was completed by 1849 people aged 18–64 years; this questionnaire provided information on 52 indicators (morbidity, functionality, lifestyle, social capital, accidents, healthcare use) indicators. Multivariate logistic regression models controlling for age, sex, education and employment were used to produce indicators for differences between the self-reported Roma (N = 124) and non-Roma (N = 1725) populations, as well as between observer-reported Roma (N = 179) and non-Roma populations (N = 1670). Differences between interviewer-reported and self-reported individuals of Roma ethnicity in statistical inferences were observed for only seven indicators. The self-reporting approach was more sensitive for two indicators, and the observer-reported assessment for five indicators. Based on our results, the self-reported identity can be considered as a useful approach, and the application of observer-reporting cannot considerably increase the usefulness of a survey, because the differences between Roma and non-Roma individuals are much bigger than the differences between indicators produced by self-reported or observer-reported data on individuals of Roma ethnicity.