Despite a campaign and attempts by the Mexican government to prevent mosquito borne viruses this year, the numbers have climbed in respect to chikungunya, dengue fever and now the introduction of autochthonous, or locally acquired cases of Zika virus.

Aedes aegypti/CDC
Aedes aegypti/CDC

Since the first local transmission of chikungunya in Chiapas, Mexico 13 months ago, the cumulative total has reached 11,199 autochthonous cases as of mid-December 2015, according to the Pan American Health Organization (PAHO).

Now, the Mexican Department of Epidemiology says the mosquito borne viral infection has spread to 28 states, with Veracruz, Michoacan, Guerrero, Oaxaca and Chiapas being hit the hardest.

The number of dengue fever cases in Mexico topped the 200,000 mark in November, according to the PAHO. In addition, 31 dengue-related fatalities have been reported year-to-date. All four dengue serotypes have been reported in Mexico this year.

Finally, one month ago, national health authorities in Mexico notified PAHO/WHO of 3 cases of Zika virus infection, including two autochthonous cases (residents of Nuevo León and Chiapas) and one imported case (with history of travel to Colombia).

Chikungunya, dengue fever and Zika virus are viral diseases transmitted by the bite of infected mosquitoes such as Aedes aegypti and Aedes albopictus.

Chikungunya can cause high fever, join and muscle pain, and headache. It does not often result in death, but the joint pain may last for months or years and may become a cause of chronic pain and disability. There is no specific treatment for chikungunya infection, nor any vaccine to prevent it. Pending the development of a new vaccine, the only effective means of prevention is to protect individuals against mosquito bites.

The symptoms of dengue fever range from mild fever, to incapacitating high fever, with severe headache, pain behind the eyes, muscle and joint pain, and rash.

Severe dengue (also known as dengue hemorrhagic fever) is characterized by fever, abdominal pain, persistent vomiting, bleeding and breathing difficulty and is a potentially lethal complication, affecting mainly children.

Zika virus infection presents with a moderate clinical picture, including mild fever; rashes that tend to begin in the face and spread to the rest of the body; joint pain, particularly in the hands and feet; muscle pain; headaches; and conjunctivitis, among other symptoms.

Infected people may not develop symptoms. Among those who do get symptoms, onset tends to be three to twelve days after the mosquito bite. Symptoms can last between two and seven days, and people rarely require hospitalization.

The symptomatology tends to be very similar to that of dengue or chikungunya, which means that it can be easily mistaken for one of those illnesses.

Complications (neurological, autoimmune) are rare, but have been described in the outbreaks in Polynesia and South America.


Robert Herriman is a microbiologist and the Editor-in-Chief of Outbreak News Today and the Executive Editor of The Global Dispatch

Follow @bactiman63