Source: ww.telegraph.co.uk
“This is the worst day of my life” she kept on crying. Nobody had a clue that the red rash on my skin and itching would have such devastating consequences. “Why me, why my baby….why us?” she asked.
Mosquitoes spread many disease-causing viruses and parasites between people and other animals, including viral infections such as dengue, Chikungunya and now Zika.
It is important for us to have the exact knowledge on the distribution of Aedes aegypti on the global scale as the spread of this mosquito to different continents is fuelled by the increase in global trade and travel.
It is seen that Aedes has spread extensively on all continents, including North America, Europe & Asia. Speaking about Zika, almost 3 to 4 million people are at risk in the past 9 months, 23 countries have reported these cases and more than 4,000 babies are born with microcephaly.
“Last year, the virus was detected in the Americas, where it is now spreading explosively,”
– WHO Director-General Margaret Chan
“The level of alarm is extremely high.”
-WHO Director-General Margaret Chan
Both these disturbing statements have shaken the public health authorities and have forced all government agencies to strengthen their disease surveillance in order to curb this potential global pandemic. The race is on to stop this deadly VIRUS.
In any potential outbreak, WHO plays an important role in calling the shots. Such a declaration of “Emergency” would trigger urgent mobilization of resources, scientific research, and vaccine development that could stop a deadly outbreak in a more efficient and less bureaucratic way.
Zika was discovered in Uganda in 1947 by a group of scientists from the Rockefeller Foundation. They experimented on Asian lab monkeys and American research mice. It was seen that the mice experienced milder form of the disease then.
Now, before we go into detail, let me explain more about sylvatic cycle. “Sylvatic” mean “occurring in or affecting wild animals.” The sylvatic cycle is the fraction of the pathogen population’s lifespan spent cycling between wild animals and vectors. Humans are usually an incidental or dead-end host, infected by a vector. In other words, human are the unlucky ones….
Scientist proved that Zika was carried by Aedes africanus mosquito in the African continent for millenniums and now it shows that people are acquiring infection from two other Aedes mosquito species; aegypti and albopictus which are now spreading Zika all over South America, constantly moving from one species to another.
Lets take another example, based on Laurie Garrette’s write up: In 2014, chikungunya was found in Africa and Southeast Asia but by the summer of 2015, the U.S. Centers for Disease Control and Prevention identified human cases of the mosquito-carried disease all over the Americas. Within two years, Chikungunya has gone from a tropical disease to a global phenomenon, infecting new animals, mosquitoes, and human beings.
So it seems like the culprits are evolving tremendously. In 1993 Chinese study suggested that Culex mosquitoes could spread dengue viruses as well while researchers in Senegal captured 13 mosquito species in West Africa, and found Zika viruses in 10 of them, including African forms of Aedes and Culex. Further work in Senegal showed that a long list of viruses including dengue, yellow fever, Zika, and chikungunya infected African monkeys, as well as multiple species of mosquitoes, shifting from sylvatic cycles.
Well, it is clear now that these viruses mutates dramatically and move on from species to primates and even to humans.
Speaking about the clinical manifestations of Zika, the first confirmed Zika case was reported in May 2015 by the Pan American Health Organization (PAHO) in Brazil. The outbreak in Brazil led to reports of Guillain-Barré syndrome and pregnant women giving birth to babies with birth defects and poor pregnancy outcomes that shocked the entire nation. It was also reported that the most common symptoms of Zika virus disease are closely related to fever, rash, joint pain, and conjunctivitis (red eyes). The illness can last from several days to a week.
Countries that are currently affected are:
- Barbados
- Bolivia
- Brazil
- Colombia
- Dominican Republic
- Ecuador
- El Salvador
- French Guiana
- Guadeloupe
- Guatemala
- Guyana
- Haiti
- Honduras
- Martinique
- Mexico
- Panama
- Paraguay
- Puerto Rico
- Saint Martin
- Suriname
- S. Virgin Islands
- Venezuela
- Samoa
- Cape Verde
Zika is primarily transmitted through the bite of an infected Aedes species mosquito. These are the same mosquitoes that spread dengue and chikungunya. These mosquitoes usually lay eggs in standing water such as buckets, flower pots and vases. There are also aggressive biters, preferred biting time are during the day and usually live indoors and outdoors near people in urban and suburban areas. Only 1 in four people develop symptoms and the onset of the disease is usually 2 – 7 days after being bitten by Aedes Aegypti
It is also said that Zika virus could be passed from mother to fetus during pregnancy. This mode of transmission is being investigated and scientist still prefers to use the word “associated” rather than “Causative-Effect”. It is also important to understand that till today, there are no scientific reports to suggest that Zika virus passes through breastfeeding. However, the spread of this virus through blood transfusion and sexual contact have been reported.
In terms of laboratory findings, Zika can only be detected in human blood during the first five days of infection and by the time individuals seek help the virus is usually undetectable. A longer-term assay, which tests for the presence of antibodies to Zika, is considered weak and it cross-reacts with dengue and chikungunya, rendering it useless in the context of concurrent spread of all three viruses.
I would also like to highlight that there are no vaccines to prevent Zika Virus till today. The prevention method lies on individual similarly to dengue. Stop Dengue & you can Stop Zika.
The basic principles are the same:
- Eliminate breeding sites
- Cover all household water tanks
- Dispose rubbish into sealed bags
- Keep drains clear
- Wear long sleeves in outbreaks areas
- Use certified insect repellents
- Take charge of your family’s health.
Keep in mind that the Minsitry of Health and scientists all around the world are working hard to curb this issue since not enough is known about Zika in order to definitively answer all the relevant questions. There are still many uncertainties about Zika, for instant the highly debatable issue of whether Zika directly causes microcephaly to infected mothers and so on.
Why are the health authorities unsure about Zika & microcephaly when the community needs an answer fast? According to one of Laurie Garrette’s write up, the WHO is cautious in using the term “Causes” microcephaly. So why is the WHO so careful about these terms?
Well here are some sets of examples from Laurie. Lets take dengue as an example, there are four types of dengue virus, and the severity of dengue varies from mild aches all the way to an Ebola-like hemorrhagic death. Scientists have been studying this for years in order to pinpoint which dengue strain causes which symptom and only now it is known that the worst outcomes arise when an individual is infected sequentially (re-infected) with different strains and not necessarily a single dengue strain. This is the reason why the WHO is carefully referring to the cases as “association” between microcephaly and Zika not cause and effect until further investigations.
I hope this short note will give us a better understanding on how challenging Zika Virus is. I share the same opinion with other Public Health leaders that the fight against Zika Virus is a long haul battle. They will mutate, hide and infect. They have no mercy. Zika will continue to haunt and endanger our future generations if no action is taken aggressively.
Dr Dhesi BR is the President of MIMPA and Founder of The Malaysian Medical Gazette. He is also currently pursuing his doctorate in Public Health. He recently won the prestigious Singularity Global Impact Competition 2015 and will be heading to the Silicon Valley, USA to represent Malaysia in NASA.
References:
- CDC Atlanta: http://www.cdc.gov/zika/prevention/index.html
- http://foreignpolicy.com/2016/01/28/the-zika-virus-isnt-just-an-epidemic-its-here-to-stay-world-health-organization/
- Control of Communicable Diseases Manual by David L. Heymann
[This article belongs to The Malaysian Medical Gazette. Any republication (online or offline) without written permission from The Malaysian Medical Gazette is prohibited.]