Monday January 16 2017

Posted by Tomas on December 27, 2016
  • Risks vary greatly across Central and South America and withing countries. Check local health statistics to assess the risk to the areas to which you are traveling. Zika is only a potential threat to women who are or may become pregnant.
    Risks vary greatly across Central and South America and withing countries. Check local health statistics to assess the risk to the areas to which you are traveling. Zika is only a potential threat to women who are or may become pregnant.
  • The tiger strips on the abdomen of the Aedes aegypti identifies them as the threat
    The tiger strips on the abdomen of the Aedes aegypti identifies them as the threat
  • Spraying for mosquitoes in La Pa
    Spraying for mosquitoes in La Pa
  • Use mosquito repellents containing DEET or the less effective pyrethrin, derived from a type of Chrysanthemum
    Use mosquito repellents containing DEET or the less effective pyrethrin, derived from a type of Chrysanthemum

Updated January 3, 2017, The holiday week has to be taken into account when looking t the dramatic decline in the number of new cases of Zika recorded in Mexico over the past week. Reporting of the statistics was incomplete the week prior to the holidays and since all cases of Zika are tested in Mexico City, it is reasonable to expect a rise in confirmed cases next week The testing lab is several weeks behind on confirming results. There was just one additional reported case of Zika in Baja California Sur, bringing the total to 23.

There remain no reported cases of the Zika virus in Baja California. 

The good news here is with the cooler weather in Baja California Sur the mosquito that carries the Zika virus has all but disappeared. A rise in the number of cases in the coming weeks can be part of the backlog of testing cases from the fall.

State in Mexico  Last Week   7-Day Increase 
1/8/2017 This Week
In All Mexico 7475 7575 100
Aguascalientes  1 1
Baja California
Baja California Sur 23 23
Campeche 86 86
Coahuila 58 58
Colima 276 277 1
Chiapas 769 769
Guerrero 796 799 3
Hildalgo 189 190 1
Jalisco 81 81
Michoacán 60 61 1
Morelos 254 269 15
Nayarit 39 39
Nuevo León 782 784 2
Oaxxaca 488 488
Puebla 93 93
Quintana Roo 363 363
San Luis Potosi 29 31 2
Sinaloa  56 57 1
Sonora 24 24
Tabasco  303 305 2
Tamaulipas 96 97 1
Veracruz 1789 1859 70
Yucatán  819 820 1
Zacatecas 1 1
Total Pregnant Women 4,138 4,206 68

Mexico's Zika testing results are only posted by state and do no indicate if the documented cases are locally acquired or contracted during travel. There has been virtually no mention of the local Zika cases in Baja California Sur press and the only local stories that provide clues are an increase in mosquito control campaigns in Cabo San Lucas, Comondu, and Loreto. But with the change of weather during the holiday week, it will dramatically reduce the mosquito populations and chance of infection. 

It is important to keep the numbers in perspective. About a half a million people live in Baja California Sur – and at the time of this update, there are just 22 documented cases. If the cases are locally acquired there are unarguably unreported cases and with the lag in testing, there is likely to be a further increase in the numbers from cases tested as far back as November. 

The epidemic that authorities projected last fall has yet to materialize with the notable exception of some Caribbean locations. Every US state currently has cases of Zika under treatment, but only Florida has 186 locally acquired cases, the rest were contracted during travel to infected regions. Unfortunately, the Mexican Secretary of Health statistics we quote here in this article do not differentiate between locally acquired and travel contracted cases of the disease. Puerto Rico is the hemispheric hotspot with more than 35,000 cases of Zika reported. 

The disease has not proved as disastrous to the unborn as previously anticipated either. With more than 3500 pregnant women testing positive for the virus in Mexico since January 1, 2016, only 4 babies have been born with symptoms of microcephaly. This number should rise as we move into the next 9 month period.

As we enter the cooler season here in Baja California Sur the mosquitos have all but disappeared. But because most of the peninsula never gets a killing frost it is a good idea to remain protected from mosquito bites to avoid Dengue Fever, Zika virus and Chikungunya which are present in Baja California Sur and most tropical climates. 

Do the Statistics Tell the Whole Story?

Absolutely not.

First, it is evident in the Mexican statistics that they are almost exclusively testing women, and possibly only those of childbearing years. Many people may have or have had Zika and not know it or even sought medical treatment for it. So the number of total cases is likely much higher. Since Zika can appear with limited symptoms, this is likely true everywhere.

Second, the Mexican statistics don't indicate if the cases of Zika were contracted locally or in travel. The US has more than 4800 cases and less than 200 were contracted locally (Florida). 

Third and perhaps of most concern is are the doctors actually reporting cases? In a recent personal interaction with doctors there seemed to be a "hear no evil, speak no evil" policy on the three mosquito-borne diseases. Several other diagnoses were presented for what seem to be clearly one of the three (as they present similar symptoms) before tests we insisted on proved it to be Chikungunya.

There has also been NO mention of the confirmed Zika cases in any of the local press. The only mention of increased mosquito control efforts has been in the very rural communities of the Comondu region, Loreto and in Cabo San Lucas "for control of Dengue'.

Background on the Zika Epidemic

The World Health Organization declared the Zika Virus a Global Health Emergency on February 1, 2016. The Zika Virus, when contracted by pregnant women or women trying to become pregnant appears to have a direct correlation to an increase in the birth defect microcephaly, or underdeveloped brains. By this declaration, it allows for the immediate release of special funding for research and containment. Since Late February 2016 a number of additional health problems have been linked to a Zika infection, including paralysis in adults. However, these problems are extremely rare, the major threat remains to pregnant women and their unborn child.

On April 10 the Center for Disease Control (CDC) announced that they believe the Zika virus poses a greater threat than originally thought and that contracting the virus during any phase of pregnancy can be harmful to the fetus. Direct links have been made to the virus and birth defects and it is believed that mutation in the virus from its origins in Africa have made it not only more virulent but is what has resulted in the connection to birth defects and temporary paralysis syndrome in a rare number of patients. Birth defects remain the main concern in the contraction of the virus while the general risk of other side effects remains relatively low.

We had our first two reported cases of Zika Virus in Baja California Sur as of 10-24-16. There are now 22 reported cases in BCS. There are no reported cases in Baja California

The number of infected persons is likely much higher and tested numbers really just represent a relative assessment of risk, as the vast majority of people (particularly males) contracting Zika are unaware they have had it, writing it off to a bad cold, case of the flu or travel sickness.

Zika poses a potential threat to the unborn of mothers who are pregnant or who may become pregnant in the near future. In researching the Health Ministries of several countries the definition of 'near future' appears to be about 6 months. There have also been some links to a neuro-paralysis disorder affecting both men and women. 

Should I cancel my trip to Baja?

At the current time, there are no reported cases in Baja California. But the last week of October 2016 has produced the first two reported cases of Zika Virus in Baja California Sur. I checked all the local news outlets and none of them have reported on the first two cases in Baja California Sur and it is not known if the two cases were contracted locally or a result of travel to an infected region. This year's extended dry period of the normally rainy late summer has kept the spread of the mosquitos to a minimum. The number of Dengue cases in the southern peninsula has been near record lows this year as well in Baja California Sur.

An interesting side note here is the Aedes aegypti mosquito is not found in locations higher than one mile in altitude. (Mexico City and Nairobi Kenya for example) 

The Zika virus is transmitted by the same Aedes aegypti mosquito that carries Dengue. The mosquito contagion season in Baja California Sur usually runs from late July until early November. Zika may pose a greater threat to the peninsula at that time. As of this date, the city of La Paz has authorized an early start to the 2016 mosquito eradication programs in a city that were plagued by a heavier than usual outbreak of Dengue in 2014. 

There are currently more than 3 times the number of cases in the USA than in Mexico, although all reported cases appear to have been contracted in travels to foreign locations. 

Prevention of Contraction

The Center for Disease recommends the use of a DEET-containing mosquito repellent applied over your sunscreen when traveling to areas where the Aedes aegypti, the carrier of this virus, are located. DEET (N,N-Diethyl-meta-toluamide) however is also a toxin and previously not recommended for children under 9 years of age. Some organic and less toxic mosquito repellents are available, but these are generally considered to be less effective. The effectiveness of DEET is also limited to about 4hrs between applications. The mosquito is most prevalent in tropical areas in the morning and evening hours, during rainy periods. However, I have also found the Aedes aegypti active during full moon periods in the nighttime hours and 24hrs per day in moist bathrooms. All it takes is one bite from an infected mosquito to be at risk of infection. (see other means of contraction below. 

Please recall that two decades ago it was recommended that mosquito repellent products containing DEET should not be used on children under the age of 9. 

What is the Zika Virus?

The Zika virus is caused by the bite of a mosquito and is classified as an arbovirus belonging to the genus flavivirus, which are those invertebrate animals such as mosquitoes and ticks that transmit the disease to humans. The Zika is similar to dengue, yellow fever, West Nile virus and Japanese encephalitis. It is transmitted by the bite of a mosquito of the genus Aedes, as the Aedes aegypti mosquito that causes dengue, Current evidence indicates human to human transmission is unlikely. 

Where is Zika From?

The virus was identified in 1947 for the first time in Uganda, specifically in the forests of Zika. It was discovered in a Rhesus monkey when a study of the transmission of yellow fever in the jungle was performed. The serological analysis confirmed infection in humans in Uganda and Tanzania in 1952, but it was in 1968 that the virus was isolated in samples from people in Nigeria. Genetic analyses have shown that there are two major lineages of the virus: the African and the Asian. The disease mutated somewhere in its travels to South America where this outbreak was discovered in Brazil and has become not only more virulent but caused the side effect of causing the birth defect of microcephaly.

How do you get the Zika Virus?

The #1 answer to that is almost always from the bite of the Aedes aegypti mosquito that has been infected with the virus.
On rare occasion from mother to child during the birth process
Through the transmission of blood and on rare occasion may be transmitted through sexual contact and bodily fluids.
The Zika Virus is not available in stores. 

What are the Symptoms of Zika?

Zika usually last four to seven days and may be confused with dengue.

In most cases the apparent symptoms are mild, the person may have a fever of less than 39 °C/102.2°F a headache, weakness, muscle and joint pain, inflammation usually concentrated in the hands and feet, conjunctivitis nonpurulent, lower limb edema and rash, which tends to begin in the face and then spreads throughout the body. Less often vomiting, diarrhea, abdominal pain and loss of appetite occur.

Although further study is required to determine the links to birth defects and some of these birth defects can result in premature mortality, there are no deaths directly attributed to the disease. The detrimental results appear to be limited to the unborn of mothers infected during pregnancy.

What is the Treatment for Zika?

There is no vaccine or specific treatment for Zika, only symptomatic management consisting of rest and take acetaminophen or paracetamol to control fever. 

The use of aspirin is not recommended because of the risk of bleeding that entails for many patients. It is also advised drinking plenty of fluids to alleviate the fluid loss and dehydration. To deal with the itch caused by the eruption can be used antihistamines.

Pregnant women or women trying to become pregnant should stay away from the patient at least during the first week of the disease to avoid contagion, although there have been no known incidents at this time of human to human transmission. There is the question as to whether the Zika virus can be transmitted through seminal fluids during sexual intercourse

Why the Concern?

The Aedes aegypti mosquito ranges of much of the western hemisphere from the temperate lower altitude regions of Central and South America to much of the United States. (Editor's Note: High-altitude locations near 1 mile like Denver, Nairobi, and Mexico City are not threatened by mosquitoes, although it recent years some species seem to be adapting) It is likely to eventually spread to most of these areas, particularly those that confront the tropical mosquito-borne illnesses like Dengue. The affected regions cover the homes of more than half a billion people, even a fractional statistical rise in birth defects could result in tens of thousands of children that will need lifetime care.

Center for Disease Control Recommendations

The CDC notice follows reports in Brazil of microcephaly and birth defect outcomes in babies of mothers who were infected with Zika virus while pregnant. Additional studies since the first posting of this article in January indicate a very strong correlation between the Zika virus and birth defects. 

Reference:

The Center for Disease Control Website
The Mexican Secretary of Health
Secretaría de Salud Mexico, Dept de Epidemiologia
The World Health Organization Website
BBC News

 

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