Malaria, commonly known as "pendulum", is an infectious disease caused by the infection of the malaria parasite by anOpheles mosquito bites or transfuses the blood of a person with the parasite. At present, tropical and subtropical areas such as Africa and Southeast Asia are the most common occurrences of malaria. In recent years, due to natural and human factors in China, the incidence of malaria in local areas has shown an upward trend.
So, what exactly is malaria? And how to prevent it? World Malaria Day is celebrated on 25 April, so let's take a look at malaria.
1. How is malaria transmitted?
Malaria is a vector disease that occurs in summer and autumn, mainly through mosquito bites on the skin, and in rare cases it can be caused by the transfusion of blood from plasmodium-bearings. There are four species of Plasmodium parasitoids that parasitize the human body, namely Plasmodium Vivax, Plasmodium trinadia, Plasmodium falciparum and Plasmodium ovate. Malaria patients and malaria parasite carriers are the source of malaria, and the vector is Anopheles mosquitoes.
Malaria itself cannot be transmitted directly from person to person, but populations are generally susceptible to malaria. People with poor or no immunity to malaria, such as children, pregnant women and tourists from non-malaria-endemic areas, tend to have severe symptoms and even death when infected with malaria. Neonatals in high-endemic areas can obtain antibodies from the mother through the placenta, and the antibodies gradually disappear after 3 months and are susceptible, with the highest incidence within 2 years of age. Although there is some immunity after malaria infection, it is not long-lasting; there is no cross-immunity between the various types of malaria.
Malaria is predominantly endemic in the tropics and subtropics, followed by temperate zones. In China, it is mainly Plasmodium vivax and Plasmodium falciparum, and the other two types of Plasmodium are rare. In recent years, with the development of opening up and personnel exchanges, many imported malaria cases have been found in China's mainland.
2. What are the symptoms of malaria?
Clinically, malaria is usually classified according to pathogen, and different malaria parasites can cause vivax, three-day malaria, falciparum malaria and oval malaria, respectively. Among them, vivax malaria, three-day malaria and ovale malaria attacks are more similar, after the patient is infected, there will be sudden chills, high fever, and with general aches and fatigue, generally lasting 2 to 4 hours, and then the body temperature begins to plummet and the whole body sweats; after entering the intermittent period, the onset time is 48 hours or 72 hours.
The onset of falciparum malaria is irregular, and in severe cases, brain symptoms such as headache, vomiting, and impaired consciousness may occur. If left untreated, recurrent seizures can lead to anemia, splenomegaly, jaundice, kidney failure, epilepsy, coma and death.
3. How can malaria be prevented?
Prevention of malaria consists mainly of individual prevention and group prevention. Among them, individual prevention refers to the protective measures taken by residents living in the epidemic area, or short-term entry into the epidemic area due to travel and other reasons, in order to prevent mosquito bites, prevent the onset of the disease, or alleviate clinical symptoms. If you enter the epidemic area briefly, you can start taking medicine two weeks before entering and continue until you leave the epidemic area for six to eight weeks; in the malaria epidemic season, you should use mosquito control measures such as screen doors, screen windows, and mosquito coils to avoid mosquito bites; at the same time, you must also pay attention to strengthening your physique and improving your disease resistance.
Group prevention refers to the high malaria area, outbreak area, or a large number of people living in malaria areas for a long time, in addition to strengthening individual prevention, but also to prevent transmission; according to the weak links of the transmission route, choose economical, effective and easy to accept protective measures, such as mosquito vector control, holistic preventive drugs, environmental governance, etc.
4. Is there a vaccine to prevent malaria?
Currently, there is no malaria vaccine available.
Malaria parasites are parasites with a complex life history whose antigenic properties often change, making it difficult to develop an antimalarial vaccine. And, until now, scientists have not fully figured out the complex immune response mechanisms of the human body against malaria.
Although no mature antimalarial vaccine has yet entered the market, some vaccine candidates have entered clinical trials and have produced very promising results. Since other methods of antimalarial warfare, such as drugs, insecticides and insecticide-containing nets, still fail to eliminate malaria, the development of malaria vaccines remains the most promising way to control malaria epidemics.
5. Will malaria have sequelae?
In general, malaria, if treated in time, will not have obvious sequelae. The prognosis of the first onset of vivax, trimorphic malaria and ovate malaria is generally good; falciparum malaria is treated with sufficient courses of treatment and the prognosis will not have sequelae.
However, cerebral malaria caused by Plasmodium falciparum, a small number of brain nervous system lesions caused by Plasmodium vivax, has a relatively high mortality rate, and there will be a variety of sequelae after the disease, such as hemiplegia, aphasia, strabismus, blindness, mental abnormalities, etc., so drug treatment should be selected as soon as possible.
6. Will malaria recur after cure?
After several attacks of malaria in a patient, the attack is stopped due to the immunity generated by the body or after thorough treatment, at which time the masochistic protozoa in the blood is also completely eliminated. However, after a period of dormant parasporosis, the late-onset sporozoites re-enter the bloodstream and invade red blood cells, causing a recurrence of malaria, also known as recurrence. Recurrence is mainly seen in vivax malaria and three-day malaria, the recurrence time is different, relapse is mostly within 1 year; three-day malaria is within 2 years, and some decades can also recur.
(Content provided: Dandelion Medicine Content review: Yang Tiesheng, chief physician of the Department of Clinical Laboratory, Peking University People's Hospital, and the dandelion medical team)