Watch Out: Anemia can Spread Deadly Dengue Virus

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Highlights:

• Dengue virus transmission is more likely when mosquitoes feed on the blood of infected persons who are anemic and iron deficient
• When mosquitoes bite and feed on the blood of a dengue virus infected person who is rich in iron, the gut cells of the mosquito take up the ingested iron to produce reactive oxygen. This reactive oxygen kills the dengue virus within the mosquito and prevents further transmission
• Dengue fever is a life-threatening illness prevalent in Central America and northern South America, sub-Saharan Africa, Southeast Asia and the Caribbean. Mass iron supplementation programs in these regions may reduce dengue transmission

Dengue virus transmission is more likely when mosquitoes feed on the blood of infected persons who are anemic and iron deficient, according to a recent study conducted at the University of Connecticut together with teams at King Mongkut's Institute of Technology Ladkrabang in Bangkok, Tsinghua University and State Key Laboratory of Infectious Disease Prevention and Control in Beijing and the 920 Hospital Joint Logistics Support Force in Kunming.

Quality of Blood Influences Dengue Virus Transmission

The study team including immunologist Penghua Wang from the University of Connecticut wanted to check if the quality of blood might play a part in the transmission of dengue virus since the levels of various chemicals and substances vary drastically from person to person. They wanted to then see whether this parameter can be modified to reduce dengue transmission.

Although a vaccine exists, it is dangerous to give the vaccine to someone who has never been previously infected. Health experts and public health officials are actively looking for ways to reduce the prevalence of dengue fever and reduce transmission.

‘Anemia can spread the deadly dengue virus. However, when mosquitoes suck the blood of a dengue virus-infected person who has sufficient iron, the gut cells of the mosquito take up the ingested iron to produce reactive oxygen. This reactive oxygen kills the dengue virus inside the mosquito and prevents further transmission. Thus, mass iron supplementation in dengue-endemic areas might help reduce transmission.’

The findings of the study appear in the journal Nature Microbiology.

Role of Blood Quality In Dengue Virus Transmission

• They team obtained fresh blood from healthy human volunteers, and added dengue virus to each and every sample collected
• Following this, blood from the different samples were fed to different groups of mosquitoes and the rate of infection in each group estimated
• The team found the infection rate among the mosquito groups varied widely and this variation very closely matched to the level of iron in the blood sample

"The more iron in the blood, the fewer mosquitoes were infected," says Wang. The team found it held true in a mouse model, too: mosquitoes feeding on mice infected with dengue were much more likely to acquire the virus if the mice were anemic.

Thus, the findings of the study suggest that iron deficiency can contribute to the spread of deadly dengue fever.

How Adequate Iron Levels Prevent Dengue Virus Transmission

When mosquitoes bite and feed on the blood of a dengue virus-infected person who are not anemic, the gut cells of the mosquito take up the ingested iron to produce a toxic chemical called reactive oxygen. This reactive oxygen kills the dengue virus inside the mosquito and prevents further transmission.

Interestingly, the prevalence of iron deficiency in dengue-endemic areas is high and might explain the increased virus transmission. Thus supplementing iron to the general population through health programs may reduce dengue transmission, but the team found that there is a huge catch to iron supplementation.

Caution Needed while Supplementing Iron in Dengue Endemic Areas

Malaria tends to be prevalent in areas similar to dengue. Paradoxically, plasmodium, the parasite causing malaria, grows well in iron-rich environment and can, therefore, cause severe infection in persons having adequate amounts of iron. Thus, mass iron supplementation programs need to be weighed carefully for risk-benefit balance before being introduced in such areas.

About Dengue Fever in Brief

• Dengue fever is an infectious disease caused by the dengue virus and spread by mosquitoes in the tropical areas including primarily Central America and northern South America, sub-Saharan Africa, Southeast Asia and the Caribbean
• Dengue is associated with high fever, headaches, rash, severe muscle and joint pains and extreme fatigue. Severe bleeding may occur in some patients with shock and death
• About 60 million cases are reported annually across the world with 18% having severe infection needing hospitalization with nearly 14000 deaths annually

Scope of the Study

Understanding how disease transmission occurs may help public health authorities take proper preventive measures in place, not only for dengue virus but other infections such as Zika virus and West Nile virus.

In summary, in areas where iron deficiency anemia is prevalent the rates of dengue virus transmission is higher. Therefore, public health officials should consider mass iron supplementation after weighing the risks and benefits to prevent this devastating mosquito-borne disease.

Reference:

1. Anemia May Contribute to the Spread of Dengue Fever - (https:today.uconn.edu/2019/09/anemia-may-contribute-spread-dengue-fever/)

Source: Medindia

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