O-positive individuals in Chikungunya risk?

O-positive individuals in Chikungunya risk?

Were you infected by Chikungunya virus (CHIKV)? So surely you may remember those harsh symptoms like high fever, severe joint and muscle pain and maculopapular rash. Are you O-positive like me? So we both have an additional risk of acquiring CHIKV disease more than others. Latest investigation reveals that there is a possible association of blood group, age and gender with CHIKV disease.

In Sri Lanka, Chikungunya fever was first emerged as an epidemic in mid October 2006, mostly from Colombo, Kalmunai, Mannar,Batticoloa and Jaffna districts. First, the blood samples of infected patients from above districts were virologically tested on dengue,measles and rubella at the Medical Research Institute (MRI),Colombo. Since the samples were negative to these diseases, this viral disease was suspected as chikungunya as it caused a recent outbreak in India at that time. Then the samples were tested for Chikungunya at MRI, Molecular Medicine Unit of the Department of Microbiology at University of Kelaniya, Genetech Research Institute Colombo, Armed Forces Research Institute of Medicine (AFRIM) laboratories of Thailand and National Institute of Virology in Pune, India. Experimentally, it was proven that more than 60% of the tested samples were chikungunya positive and therefore the epidemic was identified as chikungunya fever which was transmitted by Aedes mosquitoes. With the support from health administrators, epidemiologists, hospital staff and public, the epidemic situation was under controlled for some extent. After 2006/2007 epidemic records, chikungunya fever was emerged from time to time, but not much as in epidemic level.

Chikungunya virus (CHIKV), which is classified into genus Alphavirus, family Togaviridae, is transmitted by Aedes mosquitoes i.e. Aedes aegyptii and Aedes

albopictus. This was first reported from Makonde plateau,Tanzania during 1952-53. Since then,this virus devastates Africa, India and South East Asia being responsible for major explosive epidemics. CHIKV is an enveloped virus which contains positive sense single stranded RNA as its genome. It is about 11,805 nucleotides in length and contains ORF1 (Open reading frame 1) and ORF2 which is about 7422 and 3744 nucleotides in length respectively.Three types of CHIKV phlogroups are recognized on the basis of analyzing E1 gene sequence of viral genome.The first phylogroup of CHIKV was isolated in West Africa; the second phylogroup was isolated in East, Central and South Africa; and the third phylogroup was isolated in Asian countries. This vector borne disease is responsible for high mortality during recent outbreaks all over the world, thus the National Institutes of Health (NIH) declared CHIKV as a high priority pathogen. RT-LAMP assay is a good method used for rapid, real-time detection and quantification of CHIKV acute phase samples and also it is an important tool for CHIKV detection in developing countries.

A latest research revealed that there are some apparent relationships related to CHIKV with respect to blood group, age and gender of a particular individual. This research was conducted by a group of researchers including Naresh CVM Kumar, Mahathi Nadimpalli and Sai DVR Gopal from Department of Virology, College of Sciences, Sri Venkateswara University, Tirupati, India andVishnu R Vardhan from C R RAO Advanced Institute of Mathematics, Statistics and Computer Science (AIMSCS) – DST, University of Hyderabad Campus, Hyderabad, India.

The relationship between diseases and blood groups are always being studied and under controversial discussions. For the occurrence of some diseases like plague, small pox, malaria,cholera, there is a possible relationship related to blood groups of population. But there are limited number of studies has been reported on the relationship between CHIKV infection and blood groups. This study was designed to determine the relationship between CHIKV infection and ABO/Rhesus blood groups, age and gender.

In the present study 1500 individuals were registered and data was collected from them. The risk to be infected by CHIKV disease and its connection with factors such as blood group, age and gender was statistically analyzed. The data of this study indicated a possible association between blood group, age and gender of the sample population with CHIKV infection.

Results –

Among 1500 individuals registered in the study, 860 (57.3%) were males and 640 (42.7%) were females. Among them 513(34.2%)reported

to have acquired CHIKV infection and 987(65.8%) individuals reported absence of CHIKV fever. Based on blood group antigens the individuals were categorized into four groups, A (324), B (483), AB (162) and O (531). (Figure 1)

Conclusion –

The probability of acquiring CHIKV disease by O positive individuals was 2.2 times more than O negative individuals. The probability of acquiring CHIKV disease by A positive individuals is 2.8 times more than A negative. In the same manner the probability of acquiring CHIKV disease by B positive individuals is 1.7 times more than B negative individuals and for AB positive individuals, the probability of acquiring CHIKV disease is 3 times more than AB negative individuals. So it is apparent that the probability of acquiring CHIKV disease is high in Rh positive individuals than Rh negative individuals. The relationship between the status of CHIKV and the age in all blood groups is illustrated in Figure 2. The individuals below 30 age group are found to be more susceptible in acquiring CHIKV disease. And also male individuals are 1.3 times more susceptible in acquiring CHIKV disease when compared to female individuals.In conclusion, these results indicate that blood group, age and gender have an association with the CHIKV infection. It is observed that the Rh positive individuals are more susceptible than Rh negative individuals in acquiring CHIKV disease. Results also indicated that infections were higher in adults belonging to the age group below 30 years and also higher in males than females who participated in this study.

Here in this study we have noticed that among individuals below 30 age range, it is more susceptible in acquiring CHIKV disease. For this observation some fair reasons like the movement of people outdoors during day time when the activity of Aedes mosquitoes is in its peak, lesser personal protection towards mosquitoes in day time and different immune responses of different individuals to CHIKV disease may be responsible.

This is the second study which analyses the possibility of an association of blood groups with CHIKV disease. For further explanations identification of human cell surface receptors for CHIKV and its molecular and functional studies will necessarily be helpful in revealing the association of blood group antigens and CHIKV infections.

Appendix –

References –

• http://www.virologyj.com/content/7/1/140