Mosquitoes and men

Now that the World Health Organization has declared the Zika virus an international public health emergency, you can expect some degree of panic, and all kinds of social responses.

An example is the Indian company Tata Motors, which had just unveiled a new small car called Zica (for “zippy car”). It has announced that it would be changing the name.

The Zika virus actually causes only mild symptoms, with no long-term harm; in fact, it’s estimated that only one in five infected people will have those symptoms, which are very general, including fever, rash, pain in the joints, and red eyes.  After a patient recovers, the virus does not stay on in the body, and the patient becomes immune.

Microcephaly

Perhaps the strongest image of Zika for many people is that of mothers carrying infants with very small heads—a condition called microcephaly.  The problem is that there are now very strong suspicions that a pregnant woman who gets infected runs a higher risk of giving birth to a child with microcephaly: unusually small head and brain damage. I use “suspicions” because epidemiologists—scientists who look at the spread of diseases—are still studying the outbreak to establish if there is an actual cause-and-effect relationship between a Zika infection and microcephaly.

Epidemiologists are very cautious about making conclusions.  What they do know is that after the current Zika outbreak began in Brazil last year, the number of babies born with microcephaly has increased in great numbers, with a similar pattern in other Latin American countries.

Researchers are looking into the possibility that microcephaly might be caused by the Zika virus together with other viruses such as German measles (rubella) or toxoplasmosis (a disease caused by a parasite found in undercooked contaminated meat, as well as in the feces of infected cats).  Mothers who are severely malnourished or who have diabetes also have a greater risk of having a child with microcephaly.

Infection with the Zika virus can also be linked to defects in vision and hearing, even without microcephaly.

In an outbreak in French Polynesia in 2013, doctors also found, among those infected with Zika, cases of Guillain-Barre syndrome, a disease marked by paralysis, suggesting that Zika attacks the nervous system.

If indeed there is a causative relationship, then Zika will be very problematic. Public health authorities in Latin American countries have urged couples to avoid getting pregnant, which can be difficult for Catholics because of the ban on artificial contraception.

That hurdle will apply to the Philippines, where the church hierarchy has opposed the use of condoms even for the far more serious HIV (human immunodeficiency virus), which causes AIDS.

There are already reports from Latin America of wealthy pregnant women having amniocentesis to test fetal fluid for the Zika virus.  The procedure is risky for the fetus and brings up another controversial ethical issue: If the fetus tests positive, will the parents resort to abortion?

The advice to prevent pregnancy becomes even more important because there have been three confirmed cases of sexual transmission of the virus, specifically from an infected man to a woman.  But these are only three cases reported since 2008.  The US Centers for Disease Control and Prevention (CDC) has since issued guidelines suggesting that pregnant women avoid contact with semen from men who have just returned from places with known Zika transmission, and that the men use condoms. The British are even more specific, suggesting the use of condoms for at least 28 days after the men return from a country with infections.

More than human males, the greater threat of transmission comes from mosquitoes, the Aedes type in particular. The CDC likes to show a map to assure Americans that diseases transmitted by Aedes are limited to southern Texas and southern Florida.

That is not good news for the Philippines because Aedes thrives in all parts of the country, transmitting the dengue virus in large numbers.  Last year there were more than 100,000 dengue cases reported in the Philippines.  That means that if we do get a large number of Zika infections, it could spread quickly, on a scale similar to dengue.

Right now, what seems to be protecting the Philippines is geography and the relatively low virulence of the disease.  It was first reported in the Zika forest in Uganda in 1947. Since then, there have been outbreaks in Africa and Asia, with one report from Cebu in 2012, but the number of cases would quickly subside.

The outbreak in Brazil is different, spreading to several Latin American countries since initial reports in May 2015.  Initially, the disease will have to spread throughout the United States and Canada first, before reaching the Philippines, but I had forgotten that with the extent of the Filipino diaspora, we do have Filipinos who go through Latin American countries, notably seafarers, with Brazil having several ports of call for ships with Filipinos.

Global emergency

How serious is the threat to the Philippines and the world?

The WHO’s declaration of a public health emergency is partly political because this global body was heavily criticized for being slow to react to the Ebola outbreak that began in March 2014, and which has only recently been contained.

By declaring an emergency, global resources can now be poured into Zika research, particularly the search for better and more rapid forms of diagnosis, and for a vaccine.

As with so many other diseases, the Zika outbreak in Latin America is showing once again the relationship between poverty and illness.  The poor are more vulnerable because their communities often have the conditions—stagnant water, for example—for the mosquitoes to breed.  The higher population density also makes it easier for the mosquitoes to spread the virus from one person to another.

The US CDC’s suggestions for prevention of mosquito bites show again how the poor will be disadvantaged: Sleep under mosquito nets, use insect repellent and clothes impregnated with permethrin, wear long pants, long sleeves, shoes and hats… and stay in screened or air-conditioned rooms.

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