Why is dengue fever cyclical?

Dengue is a viral disease caused by any one of four antigenically distinct serotypes. It is transmitted by the Aedes mosquito and infects 80 million people each year.

Dengue fever (DF) is an acute viral fever characterized by headache, bone or joint and muscle pain, rash, and leukopenia. Dengue hemorrhagic fever (DHF) is characterized by four main manifestations: high fever, hemorrhagic phenomena, often hepatomegaly, and, in severe cases, signs of circulatory failure. Such patients may develop hypovolemic shock due to plasma leakage. This is called dengue shock syndrome (DSS) and can be fatal.
Dengue fever or dengue-like epidemics have been reported during the nineteenth and early twentieth centuries in the Americas, Southern Europe, North Africa, the eastern Mediterranean, Asia and Australia, and on the islands Various islands in the Indian Ocean, southern and central Pacific and Caribbean. Incidence over the past 40 years and in 1996, 2500 out of 3000 million people lived in areas with potential risk of dengue virus transmission. Every year, it is estimated that there are 20 million dengue infections, resulting in approximately 24,000 deaths.

Increased dengue transmission cycles to coincide with the rainy season have been observed in some countries. The interaction between temperature and precipitation is an important determinant of dengue transmission, and weather and temperature affect mosquito maturation, thereby influencing disease transmission.
Moreover, rainfall and temperature are the main breeding seasons for mosquitoes. Although dengue can affect people of all ages in areas where dengue has occurred, most cases of dengue occur in children under 15 years of age.
Dengue fever usually occurs during and immediately after the rainy season in tropical and subtropical areas such as Africa, Southeast Asia, China, India, the Middle East, the Caribbean, and Central Asia. America, South America, Australia and the Southwest Pacific. Once you have recovered, your body will be immune to the disease, but you can only fight the virus that caused it. Meanwhile, there are 4 different strains of the virus, which means you can still get infected with another virus. Therefore, it can be said that dengue fever is cyclical.

The first sign of the occurrence of dengue was recognized in the Philippines in 1953. The syndrome was etiologically related to the dengue virus when serotypes 2, 3 and 4 were isolated. from patients in the Philippines in 1956; Two years later, dengue viruses of various types were isolated from patients during an outbreak in Bangkok, Thailand. Over the next three decades, the DHF and DSS were re-organized to be held in Cambodia, China, India, Indonesia, Laos, Malaysia, Maldives, Myanmar, Singapore, Sri Lanka, Vietnam and several other island groups belonging to the group. Pacific.
During the 1960s and 1970s, DHF and DSS gradually increased by health problems, spreading from its primary location in large cities to smaller cities and towns in endemic countries. It established seasonal epidemics and cyclical patterns, with large outbreaks occurring over a 2-3 year period. During this period, 1070207 cases of illness and 42809 deaths were reported, mainly in children.
During most of the 1980s, in the endemic countries of China, Indonesia, Malaysia, Myanmar, Philippines, Thailand, and Vietnam, DHF and DSS spread to the suburbs, affecting rural areas as well. Exceptional large outbreaks occurred in Vietnam (354517 cases in 1987) and Thailand (174285 cases in 1987). The total number of illnesses and deaths from DHF and DSS reported in all countries of the Western Pacific and Southeast Asia for the decade of the 1980s were 1946965 and 23793, respectively. found in China (1985), Maldives (1985), India (1988), New Caledonia (1988), Sri Lanka (1989) and Tahiti (1989).

In each of these regions, where dengue has become endemic, the sequence has been more or less the same; frequent dengue transmission Virus, first associated with sporadic cases of DHF, followed by outbreaks of DHF which gradually became more frequent, until dengue cases occurred. every year, with major epidemics occurring over a period of 3 to 5 years.
All four dengue serotypes were present in these two regions. In many countries, DF and DHF are mainly diseases of children, because these are susceptible subjects with low resistance. Dengue fever and sometimes DHF, also occur in tourists. DHF is currently an important public health problem in countries in the tropical regions of Southeast Asia and the Western Pacific. It is among the top ten causes of hospitalization and death among children in at least eight tropical Asian countries.
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The article references the source: who.int, ncbi.nlm.nih.gov