Tropical diseases are found exclusively, or mainly, in the tropics, areas of the world that have a humid or warm climate. They are caused by parasites or viruses and are transmitted mainly by insects (for example, malaria or the Zika virus) or contaminated water (for example, hepatitis A or schistosomiasis).
Geographical distribution of the diseases coincides almost exactly with the location of under-developed or developing countries: Sub-Saharan Africa, Central and Southern America, the Middle East and Southeast Asia. However, increased migration and a tendency towards globalisation over the last few decades have lead to their expansion worldwide and it is essential, therefore, that we are aware of them.
First of all, the diseases transmitted by parasites are, by far, the most common. As mentioned above, the most relevant one is malaria, although others such as leishmaniasis and sleeping sickness are also common. Almost all of them are transmitted through insect bites (mosquitoes, flies and bedbugs). Most affect the male and female genitalia, amongst other organs, and cause infertility. They can also cause pregnancy loss and malformations since there have been documented cases of transmission from mother to child during pregnancy in almost all the diseases.
Viral diseases, on the other hand, include those that are transmitted through mosquito bites (for example, the well-known Zika virus, yellow fever and dengue fever) as well as others transmitted through water or food in poor condition (for example, hepatitis A). Transmission from a mother to her unborn child is not unheard of in these cases.
Avoiding contagion is a leading worldwide priority. As well as reducing mortality rates, particularly amongst infants, particular attention needs to be paid to women or couples who wish to get pregnant after having been exposed to these diseases. There are two main groups to take into account: people who travel to risk areas and people living in those areas who move to our region of the world, whether this be temporarily or permanently. The most important thing is to seek advice from specialists in tropical diseases when planning a trip, as well as being assessed on returning home (or, in the case of locals, when emigrating). On the whole, the main preventive measures include:
- Vaccination: in particular, against hepatitis A and yellow fever. Additionally, diseases such as tetanus and measles are very common in these countries so it is essential that vaccinations are kept up to date.
- Understanding the available means of protection in order to avoid insect bites, as well prevention measures with reference to food and water consumption and personal hygiene in the case of diseases that are transmitted through contaminated water.
- In the case of malaria, taking medication that prevents the disease from developing after being accidentally bitten. This is what we call chemoprophylaxis.
- Adhering to WHO or Ministry of Health recommendations when travelling to countries of risk.
There are a number of tests for many diseases that can determine if a person has been infected or not. However, these are not 100% reliable. Should a couple wish to get pregnant, even if contagion is not confirmed, a safety period is recommended (generally no more than 1 month), but should contagion have been confirmed, it will be necessary to wait until the germ has been totally eliminated and this process generally takes several months.