Evaluation of serological test of Zika in an endemic area of flavivirus in the Colombian Caribbean.

The Zika virus (ZIKV) is an emerging flavivirus transmitted primarily through arthropods, endemic in Africa, Asia, and the Americas, and is considered a global threat by the World Health Organization. OBJECTIVE: To evaluate a commercial Zika virus test (IgG/IgM catalog number B815C, Biocan, Canada. METHODS: We evaluated 30 sera of patients diagnosed with Dengue, Leptospira, Malaria, Hantavirus, and Chikungunya. To establish the sensitivity of the test, two groups of sera were analyzed, the first one was patients with Zika RT-qPCR positive, and the second were patients RT-qPCR negative but with clinical suspicion of Zika. RESULTS: The specificity was of 23.3% (7/30), the sensitivity in acute patients with positive RT-qPCR was of 63.6%, the patients with clinical suspicion of Zika the sensitivity (IgM) was of 80% (n = 8/10). Overall sensitivity (IgM) of both groups was of 71.4% (15/21). CONCLUSIONS: The test showed a low specificity to be used as a serological test in an endemic area of flavivirus infection.

Lessons learned of emerging Chikungunya virus in two populations of social vulnerability of the Colombian tropics: epidemiological analysis.

BACKGROUND: Notwithstanding the strong epidemiological impact of the Chikungunya in the Colombian Caribbean, in 2014, not the entire population were affected in the same way. This study describe the demographic, socio-economic, clinical and epidemiological aspects of the de Chikungunya in Ovejas and Corozal, two neighboring municipalities with high vulnerability in health in the Colombian Caribbean. METHODS: A cross-sectional study was performed in February 2015. A convenience sampling was carried out in 971 families affected with chikungunya. Also, a socio-demographics, clinical and epidemiological questionnaire was carried out for people who met the definition of suspected Chikungunya clinical case. For the statistical analysis, data and variables, frequencies, proportions and means were compared in the two municipalities studied. A logistic regression model was constructed to explain the effect of factors studied on the risk of family infection (RFI) or likelihood of contagion within each household. Was used the software EpiInfo 7.2.2.2 and a significance level with p-value < 0.05. RESULTS: In Ovejas, 516 households were affected by Chikungunya, 48% (1269/2631) of their inhabitants became sick; in Corozal, 455 families were affected and 42% (839/1999) of their members became sick. The evolution of the epidemic curves of Chikungunya outbreak was different in the two studied areas, the disease was more aggressive in Ovejas. Ten variables were pre-selected by univariate analysis to explain the RFI by Chikungunya, and were integrated into a logistic regression model. The final model was constructed with the following variables: municipality, gender, occupation, family income, use of repellent and fumigation. The logistic model was assessed as appropriate; however, the biases in the selection of the surveyed dwellings and in the selection of symptomatic patients could influence the results. CONCLUSIONS: It was demonstrated the epidemiological complexity of Chikungunya and the serious problem caused in populations with high vulnerability in health. The accurate association observed in the logistic regression model suggests the role of the factors studied as determinant in the rate of infection of the Chikungunya; coverage problems and surveillance in health care, demographic aspect, socio-economic problems and lack of preventive measures could explains the risk of family infection by Chikungunya in some areas tropics of Colombia. TRIAL REGISTRATION: number approval 007-2016 ethics committee-IIBT.

Epidemic outbreak of Chikungunya in two neighboring towns in the Colombian Caribbean: a survival analysis.

BACKGROUND: The first autochthonous Chikungunya virus transmission in Colombia was reported in September 2014. Three months later, every town in the Caribbean region was affected, including the bordering towns of Ovejas and Corozal, in the department of Sucre. The objective of the study was to analyze and compare the temporal dynamics of the outbreak of Chikungunya in two towns of the department of Sucre. METHODS: Households with suspicious cases with clinical symptomatology for Chikungunya were enrolled. In each house an epidemiological questionnaire was applied to collect economic and social information and methods for vector control. RESULTS: The study analyzed data collected between 09/01/2014 and 01/31/2015; 458 families in Corozal and 516 families in Ovejas were identified with Chikungunya cases. Estimated attack rates were 10,621 cases and 1640 cases per 100,000 inhabitants, in Ovejas and Corozal, respectively. The 75-day survival curve was 27.2% lower (0.632, CI = 0.614-0.651) in Ovejas than in Corozal (0.904, CI = 0.891-0.917). After 120 days, both curves showed a stable horizontal slope, close to a survival probability of 0.54, indicating the end of the epidemic period. The log-rank test (X2 = 94.6, 1fd, p-value = 0.000) showed the improved survival of Chikungunya in the town of Corozal. The relative risk between the two towns was 0.863 (CI = 0.809-0.921; p-value < 0.001). CONCLUSIONS: The dynamics of the temporal distribution of CHIKV could be influenced by socioeconomic and preventable risk factors. Poor socioeconomic conditions such as the lack and poor efficiency of water supply and waste collection services could be determining factors in the proliferation of CHIKV. The survival analysis proved to be a suitable method for studying the presentation of CHIKV and can be applied to other prevalent vector-borne diseases such as the ZIKA and Dengue.