Sensitivity of diagnostic methods for Mansonella ozzardi microfilariae detection in the Brazilian Amazon Region

• Published in: Memórias do Instituto Oswaldo Cruz Vol. 113; no. 3; pp. 173 - 177
• Main Authors: Medeiros, Jansen Fernandes, Fontes, Gilberto, Nascimento, Vilma Lopes do, Rodrigues, Moreno, Cohen, Jacob, Andrade, Edmar Vaz de, Pessoa, Felipe Arley Costa, Martins, Marilaine
• Format: Journal Article
• Language: English
• Published: Brazil Instituto Oswaldo Cruz, Ministério da Saúde 01.03.2018; Fundação Oswaldo Cruz (FIOCRUZ)
• Subjects: Bayesian model; Mansonella ozzardi; mansonelliasis; PARASITOLOGY; Solimões River; TROPICAL MEDICINE; Mansonella ozzardi; mansonelliasis; Solimões River; Bayesian model
• ISSN: 0074-0276; 1678-8060; 1678-8060
• DOI: 10.1590/0074-02760170321

The human filarial worm Mansonella ozzardi is highly endemic in the large tributaries of the Amazon River. This infection is still highly neglected and can be falsely negative when microfilariae levels are low. This study investigated the frequency of individuals with M. ozzardi in riverine communities in Coari municipality, Brazilian Amazon. Different diagnostic methods including polymerase chain reaction (PCR), blood polycarbonate membrane filtration (PCMF), Knott's method (Knott), digital thick blood smears (DTBS) and venous thick blood smears (VTBS) were used to compare sensitivity and specificity among the methods. Data were analysed using PCMF and Bayesian latent class models (BLCM) as the gold standard. We used BLCM to calculate the prevalence of mansonelliasis based on the results of five diagnostic methods. The prevalence of mansonelliasis was 35.4% by PCMF and 30.1% by BLCM. PCR and Knott methods both possessed high sensitivity. Sensitivity relative to PCMF was 98.5% [95% confidence interval (CI): 92.0 - 99.7] for PCR and 83.5% (95% CI: 72.9 - 90.5) for Knott. Sensitivity derived by BLCM was 100% (95% CI 93.7 - 100) for PCMF, 100% (95% CI: 93.7 - 100) for PCR and 98.3% (95% CI: 90.6 - 99.9) for Knott. The odds ratio of being diagnosed as microfilaremic increased with age but did not differ between genders. Microfilariae loads were higher in subjects aged 30 - 45 and 45 - 60 years. PCMF and PCR were the best methods to assess the prevalence of mansonelliasis in our samples. As such, using these methods could lead to higher prevalence of mansonelliasis in this region than the most commonly used method (i.e., thick blood smears).