Global status of Anaplasma phagocytophilum infections in human population: A 50-year (1970-2020) meta-analysis.

BACKGROUND & OBJECTIVES: Anaplasma phagocytophilum causes human granulocytic anaplasmosis; a febrile tick-borne bacterial zoonosis of increasing public health importance in many parts of the world which is life threatening in undiagnosed, misdiagnosed and untreated cases. In this study we determined and reported the global status of the pathogen in man. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was used to perform a systematic review and meta-analysis of data published in six electronic databases between 1970 and 2020. We pooled data using the random-effects model, performed sensitivity analysis by the single study deletion method and assess across study bias by the funnel plot and its statistical significance by the Egger's regression test. RESULTS: A total of 7018 cases of A. phagocytophilum were reported from 48,619 individuals examined across 22 countries in three continents. Overall pooled estimate was 8.13% (95% CI: 5.70 - 11.47) with a range of 4.64 (95% CI: 1.78 - 11.54) to 12.18% (95% CI: 7.66 - 18.83) across sub-groups. Regional prevalence was highest in North America 11.07% (95% CI: 3.13 - 32.38), while that in relation to study population was highest among occupationally exposed population 11.41% (95% CI: 5.69 - 21.56). INTERPRETATION & CONCLUSION: The study revealed a significant variation in the prevalence of A. phagocytophilum across Asia, Europe and North America, with the highest prevalence in North America and among occupationally exposed population. To curtail the menace of this growing public health crisis, we recommend integrated control programmes involving tick control, the use of appropriate clothing by occupationally exposed population and health education.

Worldwide meta-analysis on Anaplasma phagocytophilum infections in animal reservoirs: Prevalence, distribution and reservoir diversity.

A wide range of vertebrate species are competent reservoirs of Anaplasma phagocytophilum, where the pathogen is maintained in the enzootic cycle and transmitted to humans through activities of tick vectors. An insight into the role and diversity of these reservoirs is vital in understanding the epidemiology of this pathogen. Here, we determined the prevalence, distribution and reservoir diversity of A. phagocytophilum using a systematic review and meta-analysis. Data pooling was performed by the random-effects model, heterogeneity was assessed by the Cochran's Q-test and publication bias by Egger's regression test. Eighty-nine studies from 33 countries across 5 continents revealed A. phagocytophilum pooled prevalence of 15.18% (95% CI: 11.64, 19.57). Continental estimates varied significantly (p < 0.0001), with a range of 2.88% (95% CI: 0.25, 26.20) in South America to 19.91% (95% CI: 13.57, 28.24) in Europe. Country-based estimates ranged between 2.93% (95% CI: 1.17, 7.16) in Slovakia and 71.58% (95% CI: 25.91, 94.77) in Norway. Studies on A. phagocytophilum were concentrated in Europe (51.69%; 46/89) by continent and the USA (22.47%; 20/89) by country. Prevalence in wildlife (17.64%; 95% CI: 12.21-28.59) was significantly higher (p < 0.001) than that among domestic animals (10.68%; 95% CI: 6.61-16.83). Diverse species of wildlife, domestic animals and birds were infected by A. phagocytophilum. To curtail the public health, veterinary and economic consequences of A. phagocytophilum infections, we recommend an all-inclusive epidemiological approach that targets the human, animal and environmental components of the disease.