Malaria and Mosquito-Born Diseases: How Do They Catch on?

Under what circumstances and conditions does a mosquito-born disease initiate and latch on in an affected region? It has to be brought to the region from somewhere. This is often the case with infectious diseases, and they spread like wildfire in new areas where the local population does not have the immunity, drugs or infrastructure in place to cope with it.

Workers wait before spraying insecticide aimed at preventing the spread of Aedes aegypti mosquito. 

Zika, became a crisis in Brazil in early 2015. The first cases are thought to have come to country through traveling individuals. Genetic analysis of the strains from cases in Brazil were found to be similar to those from outbreaks in Pacific Island nations. One possibility is that an individual carrying it came from Chile, as exposure to the disease was found in a returning individual on vacation from Easter Island. Another possibility is that the virus was introduced in Rio de Janeiro following a canoe race, in which competitors from Pacific Islands were present. 

In Sub-Saharan Africa, for example, where malaria has long since taken hold, these factors describe the affected regions perfectly. They lay a solid foundation on which diseases can build a rampant and lasting presence. For regions of the world where malaria is endemic, the presence and alignment of the layers is glaringly obvious. This raises concern for parts of the world that may be extremely susceptible to the spread of current diseases or to the introduction of new diseases that could take over in a short span of time. Scientists are looking for trends in areas hit the hardest by mosquito-borne diseases in order to create solutions to existing problems and hopefully prevent crisis in the future.

The following excerpt is from an article detailing the multi-level array of factors that contribute to the ideal environment in which mosquito-borne diseases like malaria thrive. For the whole article by Dr. Vittor from the University of Florida School of Medicine, click here.

Zika and Malaria: the Dangerous Correlation

Under what circumstances and conditions does a mosquito-born disease initiate and latch on in an affected region? It has to be brought to the region from somewhere. This is often the case with infectious diseases, and they spread like wildfire in new areas where the local population does not have the immunity, drugs or infrastructure in place to cope with it.

Workers in Rio de Janeiro, Brazil ready to begin spraying insecticide to prevent the spread of Aedes aegypti mosquito, which carries the Zika virus. From https://theconversation.com/explainer-where-did-zika-virus-come-
from-and-why-is-it-a-problem-in-brazil-53425

Zika, for example, became a crisis in Brazil in early 2015. The first cases are thought to have come to country through traveling individuals. Genetic analysis of the strains from cases in Brazil were found to be similar to those from outbreaks in Pacific Island nations. One possibility is that an individual carrying it came from Chile, as exposure to the disease was found in a returning individual on vacation from Easter Island. Another possibility is that the virus was introduced in Rio de Janeiro following a canoe race, in which competitors from Pacific Islands were present. 


In Brazil, where Zika is taking hold, these factors describe the affected regions perfectly. They lay a solid foundation on which diseases can build a rampant and lasting presence. For regions of the world where malaria is endemic, the presence and alignment of the layers is glaringly obvious. This raises concern for parts of the world that may be extremely susceptible to the spread of current diseases or to the introduction of new diseases that could take over in a short span of time. Scientists are looking for trends in areas hit the hardest by mosquito-borne diseases in order to create solutions to existing problems and hopefully prevent crisis in the future.

The following excerpt is from an article detailing the multi-level array of factors that contribute to the ideal environment in which mosquito-borne diseases like Zika thrive. For the whole article by Dr. Vittor from the University of Florida School of Medicine, click here.

How did Malaria Evolve?

A new study, from the University of Pennsylvania School of Medicine, reveals how the connection between chimpanzee and human genomes (the similarities in our DNA) may help answer this question. By analyzing the genomes of parasites that infect chimpanzees, scientists are able to understand how human-infecting malaria parasites may have evolved many years ago.

 

Chimpanzees and humans share evolutionary history, linking the evolution of malaria between our species.

In the News: Mixed Strain Malaria Infections

Malaria is caused by 5 species of parasite that is carried by over 30 different species of mosquitoes. This makes for some major complications. "We found that when hosts are co-infected with drug-resistant and drug-sensitive strains, both strains are competitively suppressed," said Mary Bushman. "Anti-malarial therapy, by clearing drug-sensitive parasites from mixed infections, may result in competitive release of resistant strains." Read the article from Emory Health Sciences here.

Mosquitoes feed often, exposing them to a variety of strains of the malaria infection.

Is Ending Malaria Possible?

Scientists and philanthropists are hopeful. Read about the fight here, and about plans from organizations who are committed to ending malaria.
For more interesting news, read the articles below.
http://www.pcmag.com/article2/0,2817,2498374,00.asp
https://www.gatesnotes.com/Health/Eradicating-Malaria-in-a-Generation

More on the Progress Being Made Against Malaria

The fight continues, and is not in vain. Based on reports from the WHO and Unicef, over 700 million cases of malaria have been prevented since 2000 as a result of efforts aimed at tackling the disease. Further, death rate has fallen by 60% over the same time period. Read the story from BBC Health News and take two minutes to watch the video about plans to make malaria "no more". A report was published last September showing the figures that support this hopeful story.

In the News: How to Beat Malaria

From BBC Health News, a report that says it is possible to completely stop deaths from malaria in the coming years. For the full story, click here.

Very Low Income Households in Malawi Carry a Disproportionate Share of the Economic Burden of Malaria

Malaria takes an economic toll for several reasons. The cost of prevention and treatment as well as the wages lost due to illness greatly burden thousands of people. From a study about the economic impact of malaria in Malawian households, it was evident how disproportionately high the toll is on the poorest families. Stagnated economic growth and abject poverty are common in countries highly affected by malaria.  

Inborn Immunity to Malaria: Sickle-Cell Anemia

Nature has devised a fascinating defense against malaria. It involves altering the very shape of the body's red blood cells (RBC). Sickle cell anemia is a disorder that changes the shape of RBC, as shown in the picture below, due to a mutation in the genetic code that is responsible for the formation of the beta-subunit portion of a hemoglobin molecule. As a result, the RBC will take a rigid sickled-shape. This leads to two important consequences: 1) malaria immunity and 2) organ damage and anemia symptoms.

Normal RBC compared with a sickle shaped one.

A mutation in the genetic code for hemoglobin causes sickle-cell anemia.
The mutation codes for a valine rather than a glutamic acid to be produced.

The Global Distribution of Anopheles Mosquito

The Anopheles mosquito is spread across the globe, and poses the threat of spreading the malaria vector worldwide. Collecting data about the mosquito type in a region provides key information about controlling populations and vector transmission.

From Kiszewksi et al., 2004. American Journal of Tropical Medicine and Hygiene 70(5):486–498

Check out the World Health Organization's world malaria report here.