The World Health Organization (WHO), through its laboratory efforts, has been trying to control and eliminate measles and rubella outbreak (World Health Organization, 2007). Thorough observation contributes to accurate identification and confirmation of the disease (Morbidity and Mortality Weekly Report, 2008). Therefore, it is critical to have access to a laboratory that can provide precise results. In 2000, WHO created the WHO Measles and Rubella Laboratory Network (LabNet) to make a uniform “testing and reporting structure” (2008). Additionally, the laboratory works to ensure that an “external quality assurance program” exists (2008). LabNet has been implemented across Europe, America, Eastern Mediterranean and Western Pacific (2007). Moreover, the lab is spread in around 166 countries, with 679 laboratories (2008). Despite the current efforts, measles and rubella surveillance continues to be insufficient, especially in regions where “collection and transportation of serum specimens” are complicated (2008). To resolve this, LabNet assessed two methods in collecting samples- dried blood spots (DBS) and oral fluid (OF) samples (2008).
LabNet staff members and scientists presented the results in a June 2007 ad hoc meeting set in Geneva, Switzerland (2008). Results show that DBS and OF methods may be used in measles and rubella surveillance, particularly in cases where refrigeration and transportation of samples may be futile (2008). However, in regions where serum-based testing is already used, LabNet concluded that conversion to DBS and OF methods are not necessary (2008). The results were published in a Morbidity and Mortality Weekly Report, a series prepared by the Centers for Disease Control and Prevention (CDC) (2008). The data are collected by CDC based on state health departments (2008).
Single serum sample has been used to detect measles and rubella among suspected cases (Morbidity and Mortality Weekly Report, 2008). Once the patient becomes symptomatic, a throat swab or urine sample are gathered, sent to the laboratory to be studied and be able to detect the “virus RNA by reverse transcription or polymerase chain reaction (RT-PCR) (2008). However, proper detection and identification of IgM and viral RNA rely on a number of things, such as accurate “collection, processing, shipment and storage” of acquired samples and the capability to ensure proper refrigeration (2008). In the some regions, transportation is a barrier to this, thus alternatives must be used.
The application of DBS in measles and rubella specific IgM and IgM and viral RNA is common in epidemiological uses (Morbidity and Mortality Weekly Report, 2008). Specifically, DBS is used in cases where refrigeration is ineffective for DBS has the capability to make antibody and viral RNA stable at ≤ 98.6 F° (2008). On the other hand, OF is used in the United Kingdom measles, mumps and rubella (MMR) surveillance programs for almost 10 years (2008). It is a simple, straight-forward method to conduct and is preferred by more people (2008).
The use of DBS and OF as alternative methods began in 2001, when LabNet laboratories in Australia, Cote d’Ivoire, Netherlands, Turkey, United States and the United Kingdom studied the stability of IgM and RNA in DBS and OF (Morbidity and Mortality Weekly Report, 2008). Additionally, they worked on perfecting the IGM and RNA detection in aforementioned methods (2008). To do so, LabNet collected OF, DBS and serum samples from suspected patients (2008). The laboratory also studied data of the MMR surveillance program in the United Kingdom. To complete the triangulation, data from the WHO African Region, which included countries such as Sierra Leone, Burkina Faso, the Democratic Republic of Congo, Ethiopia, Ghana, Senegal and Zambia, were reviewed (2008). These African countries used either DBS or serum-based (2008).
After laboratory testing was done, results show that DBS and OF testing are comparable to that of a serum-based diagnostic (Morbidity and Mortality Weekly Report, 2008). Specifically, DBS and OF sampling offer at par “sensitivity and specificity” for IgM detection compared to serum-based diagnostics, (2008). Both can also detect specific IgM and RNA, with OF having the ability to detect RNA after the rash has manifested (2008). The two alternate methods proved to be not just simple to collect but also more preferred by the public, especially since it is noninvasive (for OF) and not venipuncture (for DBS) (2008). In regions where transportation is hard, DBS and OF are most useful for both offer “stability without refrigeration” for up to 7 days and longer (2008). The stability factor is vital is minimizing transportation expenses (2008).
However, DBS and OF also have disadvantages, such as the lack of external quality assurance program, unavailability of collection devices in health-care facilities, shortage in DBS volume in cases where staff are not fully-equipped; and the fact that DBS and OF extraction procedure may rob the time of the technicians (Morbidity and Mortality Weekly Report, 2008).
While serum sampling is still the “gold standard’ in detecting IgM, LabNet and attendees of the ad hoc meeting recommended DBS and OF sampling to be alternative sampling procedures (Morbidity and Mortality Weekly Report, 2008). The uses of such techniques are recommended in situations where a transport problem arises, when refrigeration is ineffective, or when patients refuse venipuncture (2008). Furthermore, participants of the ad hoc meeting note that the use of DBS and OF would not only reduce transport cost, but would make for an easier and acceptable collection method for patients (2008). Given sufficient training and resources, DBS and OF improve sensitivity of rubella case confirmation in as early as 4-5 days after the appearance of rash (2008).
However, in regions where serum sampling is use, there is no need to switch to DBS and OF, except in special cases such as difficulty in transporting specimen to the laboratory and employing OR method to detect viral RNA once disease onset. The use of alternative diagnostic samples is a big step in hindering measles and rubella outbreak in the world.
Morbidity and Mortality Weekly Report. (2008). Recommendations from an
ad hoc meeting of the WHO measles and rubella laboratory network (LabNet)
on use of alternative diagnostic samples for measles and rubella
surveillance. Retrieved July 12, 2008 from Morbidity and Mortality Weekly
Report, Centers for Disease Control and Prevention.
World Health Organization. (2007). Manual for the laboratory diagnosis of
measles and rubella, 2nd ed., WHO/IVB/07.01. Retrieved July 12, 2008
from World Health Organization Database.