Dengue Fever

DENGUE FEVER (dengue; synonyms: febris endemica cum roseola, arthrodynia, exanthesis arthrosia, scarlatina rheumatica, rheumatismus febrilis epidemicus). The word dengue, according to Hirsch, originated from the Spanish distortion of the English word dandy, due to the similarity of the characteristic swaying gait of dengue patients (P. Manson). Dengue is an acute febrile disease caused by an unknown pathogen circulating in the blood, and is characterized by two feverish episodes with an interval of 2-3 days, severe muscle pains, and the appearance of rubella-like rashes during the second feverish episode. Etiology. The causative agent of dengue is unknown; it is found in the blood plasma and passes through a Chamberland filter; the filtrate, when injected into non-immune people, produces a typical attack of dengue fever; healthy people can be infected with the blood of these patients. The vectors of dengue fever are mosquitoes: Aedes aegypti (Aedes calopus, Stegomyia fasciata), which also transmit yellow fever (see), and Culex fatigans (the role of the latter is not recognized by all). The geographical distribution of dengue fever is associated with the distribution of the aforementioned mosquitoes. Epidemics of dengue fever have been noted in most tropical countries (on Formosa, southern China, India, the Philippines, South America, Africa and Australia), as well as in Syria, Asia Minor, the Aegean Islands, and European Turkey. Dengue fever usually affects large masses of the population at once: according to observations by Manson (P. Manson) during the epidemic in 1872 in Amoy, 75% of the population contracted dengue fever; in Cairo and Ismailia in 1889, 90% of the population was affected, in Pondicherry in India in 1924 - 50%. In 1926, dengue fever began to increase in the city of Colombo in Ceylon. Somewhat later, dengue fever appeared in southern Africa - in Durban, where 50,000 people fell ill (60 died). In 1927, dengue fever appeared in Tunisia, where 25% of the population contracted it, and in Spain (Andalusia); in September 1927 - in Syria, and in November and December - in Palestine (Jaffa). In August 1928, dengue fever appeared in Greece and soon assumed a pandemic form; in Athens, according to Sacorrafos (M. Sacorrafos), in August 400,000 people had dengue fever. A large number of dengue fever patients was also noted in other cities and islands of the Archipelago. According to incomplete data, in Greece from August to October 1928, more than 960,000 people contracted dengue fever and 1,200 died. Such an epidemic of dengue fever as in Greece in 1928 had not been noted before. In the USSR, dengue fever has not yet been established, but its transmitter, Aedes aegypti, was discovered in Batumi by Marcynowski (1911), and then by Lyakhovetsky in Poti (1913) and Lindtrop along the Black Sea coast (1924), and Culex fatigans - in Mugan (1926) and southern Dagestan (1928) (Shingarev), but these isolated findings require further confirmation. Epidemiology. Dengue fever never spreads through goods and things, but is usually brought into coastal cities by steamships that have infected mosquitoes on board. Aedes aegypti, like Culex fatigans, after drinking the blood of a dengue fever patient, become infectious from the second day. Epidemics of dengue fever have a strictly seasonal nature, associated with the development of the virus in the mosquito's body, and occur during the hottest months of the year. All ages, sexes, and races are susceptible to dengue fever. According to more recent works by Siler and Manoussakis (Siler, Manoussakis), immunity in dengue fever is very short-lived (according to Siler's indication, 121 days after recovery from dengue fever). However, as a result of repeated illnesses over a number of years, some immunity to this disease develops in the local population, and in case of illness, dengue fever runs much milder. Pathological anatomy has been little studied, as dengue fever is rarely the direct cause of death. Small inflammatory foci have been described in brain tissue and in the lungs, as well as serous effusions around the joints and an inflammatory condition of the cruciate ligaments of the knee joint. Experimental study of the disease. In experiments with human infection through mosquitoes previously fed on the blood of dengue fever patients, the incubation period was usually 5-7 days. Couvy (1921) when injecting intraperitoneally into rabbits the blood of dengue fever patients taken at elevated temperature, noted in rabbits after 4-7 days an increase in temperature lasting 48 hours, and a second attack - after 5-7 days. Both during the first and second attacks, Couvy found spirochetes in the peripheral blood of the rabbit; he also succeeded in finding spirochetes in the blood of dengue fever patients. Manoussakis' research during the last dengue fever epidemic in Greece did not confirm these observations. According to experiments by Japanese authors Koizumi, Yamaguchi, and Tonomura (1917) on Formosa, 0.00005 cm³ of serum from dengue fever patients, when administered subcutaneously, causes dengue fever in a healthy person. The virus appears in the blood 18 hours before the first attack, remains in it throughout the febrile period, and for at least 90 hours after the onset of the disease. During passages, it does not weaken. Blanc, Caminopetros, Manoussakis (G. Blanc, J. Caminopetros; 1928) showed that serum from dengue fever patients, left in an incubator at 15-18°, retains its virulence for 54 days; when heated to 50° for 1/2 hour, its virulence is destroyed. Guinea pigs inoculated with the blood of a dengue fever patient do not show an increase in temperature or any signs of the disease, and the blood remains virulent for humans for 5 days after inoculation. Clinical course. The incubation period lasts 5-7 days (see above). The clinical course of dengue fever can be divided into 3 periods: 1) initial stage, 2) stage of remission, and 3) terminal fever and appearance of rash. Initial stage. Dengue fever may be preceded for several hours by prodromal phenomena in the form of rheumatoid-like pains in the limbs or joints, but more often the disease begins suddenly. There is a feeling of being broken down, general weakness, an increase in temperature to 39-40°, and pains characteristic of this disease in the eyeballs, joints, and bones. The skin is very sensitive. The face is red, sometimes slight edema is noted. This condition usually lasts for 2-3 days, then the temperature rapidly drops with profuse sweating; sometimes the drop in temperature is accompanied by diarrhea and nosebleeds. During some epidemics, cases with a drop in temperature in the form of a lycocrisis were observed. The patient begins to feel better, the pains decrease somewhat. This stage of remission lasts from 12 hours to 2-3 days. Then unexpectedly there is a secondary rise in temperature to 38.5° (rarely to 39.5°; see figure). Together with the secondary fever (according to observations by individual authors - also in the first febrile attack), a rash typical of dengue fever appears, consisting of dark, dirty reddish spots, initially the size of a small pea, quickly merging into round, rubella-like spots from 3 mm to 12 mm in diameter; each spot is surrounded by an area of unchanged healthy skin [see color plate (Vol. IX, article Diazoreactions)]; the rash disappears on pressure and usually does not become petechial [see color plate (Vol. IX, article Diazoreactions)]; the rash in dengue fever can be described as intermediate between measles and scarlet fever. It is more abundant on the forearms, back, chest, and thighs. It disappears after 2-6 days, after which peeling begins, lasting from 2 to 3 weeks. In the blood in dengue (according to Ashburn and Craig), leukopenia is observed - up to 3,800 leukocytes in 1 mm³ (sometimes up to 1,000), with a significant increase in small lymphocytes. After the temperature drops, weakness remains for up to 3 weeks and there is a characteristic swaying gait. Diagnosis is based on the sudden onset of the disease, very severe muscle pains, a decrease in fever on the 3rd or 4th day, and the appearance of a rash with a new rise in temperature. It differs from influenza by the absence of catarrhal phenomena of the upper respiratory tract; from scarlet fever - by the absence of angina and enlargement of the neck glands; from measles - by the absence of conjunctivitis and the presence of very severe muscle pains. The prognosis is relatively favorable. Fatal cases are usually rare. Treatment is symptomatic: antipyretics, analgesics - aspirin, pyramidone, etc. Serum from convalescents from dengue fever, injected in an amount of 15 cm³ repeatedly (5 times), does not prevent the disease. Prevention - destruction of breeding places of Aedes aegypti and Culex fatigans, smoking them out of premises, mechanical prevention of housing, etc. (see Yellow fever).