Wednesday, April 25, 2018

One in four blood transfusions transmit malaria in some parts of Africa

By Esther Nakkazi

At least one in four blood bank supplies in some areas of sub-Saharan Africa contain malaria parasites putting a high risk of transfusion-transmitted malaria especially to children with anemia.

Researchers suggest that for malaria to be eliminated, all sources of disease transmission, including the region’s blood banks, need to be addressed.

“Our findings clearly reinforce World Health Organization or WHO recommendations that all transfusion recipients receive preventive malarial treatments,” said Dr. Claudia Daubenberger based at the Swiss Tropical and Public Health Institute.

According to the WHO, 90 percent of all malaria cases are located in sub-Saharan Africa. Transfusion-transmitted malaria (TTM) in this region is estimated at 28%.

The findings were from two research studies presented at the 7th Multilateral Initiative on Malaria (MIM) Pan African Malaria Conference in Dakar, Senegal on 16 April 2018.

The first study, a systematic review, and meta-analysis gathered results from 24 studies including more than 10 studies from Nigeria, Africa’s most populous country to assess malaria prevalence among 22,508 blood donors.

Also, articles from databases and clinical trial registries reporting prevalence studies of malaria parasitemia amongst blood donors in sub-Saharan Africa published between 2000 and 2017 were used.

As well grey literature sources such as the WHO website and published reports of ministries of health websites of countries and reference lists of papers were also screened. Risk of Bias was assessed using the Joanna Briggs Institute Prevalence Critical Appraisal Tool.

The pooled prevalence of malaria parasitemia found was 23.46 percent. The study showed that without better vigilance, children receiving transfusions to address malaria’s impacts like anemia risk exposure to more malaria-causing parasites.

“Our research is only the first line of inquiry needed to address this risk. Pregnant women and children receive the majority of transfusions in this region,” said Dr. Selali Fiamanya and colleagues from the Worldwide Antimalarial Resistance Network (WWARN).

The technical challenges of diagnosing and removing the Plasmodium parasites from the blood banks require further analysis, but we know already that these findings threaten the next generation—our future, said Dr. Fiamanya.

The second study, focusing on the blood supply of Equatorial Guinea’s capital, Malabo, found much higher levels of latent malaria infection, most of it—more than 89 percent—at a level that commonly used diagnostic technology cannot detect.

Typically, rapid diagnostic tests (RDTs) and thick blood smear microscopy are used to diagnose malaria, but these cannot detect latent malaria infection so low-level or asymptomatic infections can hide reservoirs of parasites that fuel future malaria outbreaks.

The study used a more sensitive diagnostic test—quantitative polymerase chain reaction (qPCR) assays, which are currently too expensive and unsuitable for most field conditions—to examine.

29.5 percent of the 200 blood samples collected in Malabo were contaminated according to the study conducted by Dr. Daubenberger and colleagues at the Swiss Tropical and Public Health Institute, and Dr. Tamy Robaina at the Malabo Blood Bank.

All of the samples thought to be free of the malaria parasite held very low concentrations of the parasites—under 100 parasites per microliter of blood said Dr. Daubenberger.

“With better screening technology and practices in place, blood banks in sub-Saharan Africa can be well placed to serve as a surveillance system, helping to monitor malaria and other transfusion-transmitted infectious diseases,” said Dr. Daubenberger.


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