Analysis of diagnostic test outcomes in a large loiasis cohort from an endemic region: Serological tests are often false negative in hyper-microfilaremic infections.

BACKGROUND: The parasitic disease loiasis is associated with significant morbidity and mortality. Individuals with hyper-microfilaremia (greater than 20,000 microfilariae per mL of blood) may suffer from serious treatment-related or spontaneous adverse events. Diagnosing loiasis remains complex and primarily relies on direct parasite detection. In this study, we analyzed the performance of various diagnostic tests and the influence of parasitological and clinical factors on test outcomes in samples from individuals living in an endemic region. METHODS: Data and samples were collected from rural Gabon. Loiasis was defined as either detectable microfilaremia, or a positive history of eyeworm as assessed by the RAPLOA questionnaire. Diagnostic testing included a quantitative PCR (qPCR) for detection of Loa loa DNA in blood samples, an in-house crude L. loa antigen IgG ELISA, and a rapid test for antibodies against the Ll-SXP-1 antigen (RDT). Sensitivity and specificity were determined for each test and factors potentially influencing outcomes were evaluated in an exploratory analysis. RESULTS: ELISA, RDT and qPCR results were available for 99.8%, 78.5%, and 100% of the 1,232 participants, respectively. The ELISA and RDT had only modest diagnostic accuracy. qPCR was specific for L. loa microfilaremia and Cycle threshold values correlated with microfilarial density. Anti-L. loa IgG levels were highest in occult loiasis, and antibody levels correlated inversely with L. loa microfilarial density as did RDT line intensities. Only 84.6% and 16.7% of hyper-microfilaremic individuals tested positive by ELISA (11/13) and RDT (2/12), respectively. CONCLUSION: None of the tests demonstrated high sensitivity and specificity for loiasis. Indirect diagnostic assays were characterized by low specificity. Additionally, hyper-microfilaremic individuals often tested negative by RDT and ELISA, indicating that these tests are not suitable for individual case management in endemic populations.

Rabies post-exposure prophylaxis of international travellers - Results from two major German travel clinics.

BACKGROUND: Travel to regions with rabies risk has increased. However, data on adequate rabies post exposure prophylaxis (PEP) abroad is scarce. The aim of this study was to assess the appropriateness of medical management following suspected rabies exposure (SRE) in international travellers. METHOD: A cross-sectional questionnaire-based study in returning travellers with reported SRE who sought post-exposure medical care was conducted in two large German travel clinics. RESULTS: The 75 included SRE cases had a median age of 34 years (range 26-43) and showed a female predominance (59%, 44/75). Most participants returned from Asia (47%, 34/72). About 28% had received pre-exposure prophylaxis (PrEP, ≥2 vaccine doses) (20/71). In 51% the animal was actively approached (34/67). All patients had category II/III exposure according to the World Health Organization (65% category III, 49/75). With 78% (52/67), most patients cleaned the wound after SRE; 36% (24/67) used water and soap. Only 57% (41/72) of participants sought medical care during their trip. Overall, 45% (33/74) received rabies vaccination abroad which corresponds to 80% out of those who sought healthcare (33/41). CONCLUSIONS: Awareness for appropriate first aid and the urgency of seeking timely professional treatment including PEP after an SRE seems to be insufficient in German travellers. Travel practitioners need to educate travellers about rabies risk, prevention measures and the correct behaviour after SRE including adequate wound treatment and seeking immediate medical help for PEP. PrEP should be offered generously especially to travellers with high rabies-exposure risk and those visiting areas with limited healthcare access.

Distinct loiasis infection states and associated clinical and hematological manifestations in patients from Gabon.

BACKGROUND: Loiasis-a filarial disease endemic in Central and West Africa-is increasingly recognized as significant individual and public health concern. While the understanding of the disease characteristics remains limited, significant morbidity and excess mortality have been demonstrated. Here, we characterize clinical and hematological findings in a large cohort from Gabon. METHODS: Loiasis-related clinical manifestations and microfilaremia, hemoglobin and differential blood counts were recorded prospectively during a cross-sectional survey. For analysis, participants were categorized into distinct infection states by the diagnostic criteria of eye worm history and microfilaremia. RESULTS: Analysis of data from 1,232 individuals showed that occurrence of clinical and hematological findings differed significantly between the infection states. Eye worm positivity was associated with a wide range of clinical manifestations while microfilaremia by itself was not. Loa loa infection was associated with presence of eosinophilia and absolute eosinophil counts were associated with extent of microfilaremia (p-adj. = 0.012, ß-estimate:0.17[0.04-0.31]). CONCLUSIONS: Loiasis is a complex disease, causing different disease manifestations in patients from endemic regions. The consequences for the affected individuals or populations as well as the pathophysiological consequences of correlating eosinophilia are largely unknown. High-quality research on loiasis should be fostered to improve patient care and understanding of the disease.

Rabies exposure in travellers to Asia, the Middle East, Africa, South and Central America-a German Airport study.

BACKGROUND: Rabies causes thousands of deaths worldwide and trips to rabies endemic countries are popular. Travellers are often uncertain whether pre-exposure prophylaxis (PrEP) is advisable since they find it difficult to estimate the exposure risk during travel and the availability of post-exposure prophylaxis in endemic regions. The aim of this study was to determine the potential rabies exposures in travellers and to assess their knowledge on rabies. Secondly, we explored the access to appropriate post-exposure medical care in respective countries. METHODS: We conducted a cross-sectional study at Frankfurt Airport. Returning adult travellers arriving from Asia, the Middle East, Africa, South and Central America were invited to participate in this questionnaire-based study while waiting in the baggage claim area. RESULTS: Over a one-month recruitment phase in March 2019, we enrolled 3066 travellers; 2929 were included in the analysis. The gender ratio was balanced; the median age was 42 years (range 18-83 years). Participants arrived from Asia (46%), Africa (29%), Central/South America (13%), the Middle East (8%) and the Caribbean (8%). Forty-five per cent sought pretravel advice and 22% received ≥2 injections of rabies PrEP. Travellers with pretravel advice from tropical medicine specialists reached significantly higher knowledge scores than others. We found that potential rabies exposure occurred in 2.0% (57/2915) of travellers with 31% (13/42) of the contacts being unprovoked; 19% (8/42) of the exposed sought medical care and 3/8 were adequately treated before returning to Germany. Risk factors for animal exposure were: male sex, young age, trips to Asia and a long stay abroad (>4 weeks). CONCLUSIONS: A total of 2% of returning travellers (n = 2915) experienced a potential rabies exposure during their journey. A majority of the exposed individuals did not seek medical care; those seeking medical care were often treated inadequately. Rabies information must be emphasised during pretravel counselling and PrEP should be offered generously, especially to travellers with high exposure risks.