Rapid Diagnostic Testing Identified Possible Zika Virus Cases in 6 Nigerian States Following Yellow Fever Outbreak Responses between 2015 and 2019 Open Access

Anyoha, Amylee (Spring 2020)

Permanent URL: https://etd.library.emory.edu/concern/etds/4t64gp154?locale=en


In October of 2016, Nigeria Centre for Disease Control (NCDC) released a public health risk assessment of Zika virus in Nigeria and interim recommendations. The recommendations stress the need for surveillance to understand and monitor the epidemiology of Zika virus in the Nigerian population with the goal of developing appropriate interventions. This study estimated the prevalence of Zika virus in North Central Nigeria using Rapid Diagnostic Tests (RDTs) on stored serum samples that had tested negative for Yellow fever between 2015 and 2019. A convenience sample of 385 serum samples were tested for IgG and IgM antibodies to Zika virus. In the final sample of 280, 27 tested positive for IgG, IgM or both type antibodies (9.64%), which were specific to Zika. Higher mean annual temperature, population density and mean annual rainfall were significantly related to a higher number of observed cases. It is possible that areas experiencing Yellow fever outbreaks are likely to see cases of Zika virus due to the shared Aedes aegypti mosquito vector. In our study, all samples were tested because they showed typical symptoms of flavivirus type diseases, of which both Zika and Yellow fever are members of. In accordance with 80% of cases expected to be asymptomatic, as stated by WHO, it is probable that the prevalence of Zika virus in Nigeria is underestimated in our data. Persons with asymptomatic infections are less likely to observe precautions of passing the virus to sexual partners, increasing the number of babies unexpectedly born with microcephaly. In the future, outbreak response for flavivirus type diseases in Nigeria should include testing for Zika virus.


Keywords: Zika virus, flavivirus, rapid diagnostic testing

Table of Contents

List of Abbreviations i

Rapid Diagnostic Testing Identified Possible Zika Virus Cases in 6 Nigerian States Following Yellow Fever Outbreak Responses between 2015 and 2019 1

Methods 5

Setting 5

Data collection 6

Sample Selection 6

Laboratory 7

Rapid Diagnostic Testing 7

Figure 1. One Step Zika IgG/IgM Antibody Test 9

Data Management and Analysis 9

Results 10

Figure 2 11

Table 1. Median and Interquartile Range for Continuous Variables Compared by Positive or Negative IgG/ IgM Result from RDT 12

Figure 3. 13

Table 2. Chisq Comparing Samples Positive or Negative for ZIKV at Median Value of Mean Annual Rainfall, Mean Annual Temperature and Population Density (n=280) 14

Table 3. Observed Number of ZIKV Positive Samples by State (n=9) 15

Model 1 16

Table 4. Odds ratio estimates for Model 1. at significance level a=.05 (n=280) 16

Model 2 16

Table 5. Odds ratio estimates for Model 2. at significance level a=.05 (n=280) 17

Discussion 17

References 20

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