Tuesday, August 16, 2016

Zika Virus is not the only serious disease carried by Mosquitos

Health Train Express has been away for part of the summer, and there is much news to report.

It is that time of the year for insect repellent. And not just for ridding the pesky evening bugs and annoying bites that ruin summer picnics, baseball games and outdoor sporting events

During the summer an airborne force in the sky (the mosquito) carries multiple threat weapons, guided by heat seeking, carbon dioxide homing missiles.   The onslaught is continuous and each season begins again as reported by the  World Health Organization. With modern prevention measures large epidemics are not prevalent. Our air defense system of mosquito control, repellents and treatment for  the diseases is vastly improved.

Mosquito-borne diseases

Mosquitoes cause millions of deaths every year

These tiny predators go after targets much larger than themselves. Many years ago scientists revealed the deadly tropical diseases spread by these vectors.  Controlling these diseases depended upon destroying the vector mosquitos.  

Here are some of the villains:


The virus is transmitted from human to human by the bites of infected female mosquitoes. Most commonly, the mosquitoes involved are Aedes aegypti and Aedes albopictus, two species which can also transmit other mosquito-borne viruses, including dengue. 

 Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection. 

Human infection is most often the result of bites from infected mosquitoes. Mosquitoes become infected when they feed on infected birds, which circulate the virus in their blood for a few days. The virus may also be transmitted through contact with other infected animals, their blood, or other tissues.
A very small proportion of human infections have occurred through organ transplant, blood transfusions and breast milk. There is one reported case of trans placental (mother-to-child) WNV transmission.
To date, no human-to-human transmission of WNV through casual contact has been documented, 

In most cases, malaria is transmitted through the bites of female Anophelesmosquitoes. There are more than 400 different species of Anopheles mosquito; around 30 are malaria vectors of major importance. Unlike Yellow Fever, Dengue, Chikungunya and West Nile Virus the pathogen is not a virus, but a parasite, P. falciparum .

Red Blood Cell with falciparum


Good and early supportive treatment in hospitals improves survival rates. There is currently no specific anti-viral drug for yellow fever but specific care to treat dehydration, liver and kidney failure, and fever improves outcomes. Associated bacterial infections can be treated with antibiotics.


1. Vaccination
Vaccination is the most important means of preventing yellow fever. In high-risk areas where vaccination coverage is low, prompt recognition and control of outbreaks using mass immunization is critical for preventing epidemics. It is important to vaccinate most (80 % or more) of the population at risk to prevent transmission in a region with a yellow fever outbreak.

Finally, the latest viral threat

Zika virus is primarily transmitted to people through the bite of an infected mosquito from the Aedes genus, mainly Aedes aegypti in tropical regions. Aedes mosquitoes usually bite during the day, peaking during early morning and late afternoon/evening. This is the same mosquito that transmits dengue, chikungunya and yellow fever. Sexual transmission of Zika virus is also possible. Other modes of transmission such as blood transfusion are being investigated.

WHO | World Health Organization
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