Orlov and Ornithodorus

ORLOV, Sergei Sergeyevich (1864–1927), professor of experimental hygiene at the First Moscow State University. Upon graduating from the medical faculty of Moscow University in 1888, he worked for 2 years as a sanitary statistician in the Moscow provincial Zemsky administration. In 1890, at the suggestion of F. F. Erisman, he traveled abroad, where he studied the methodology of sanitary and hygienic research in Zurich and Munich. In 1891, Orlov assumed the position of laboratory assistant at the Hygienic Institute of Moscow University and simultaneously

worked at the Moscow City Sanitary Station established under the same Hygienic Institute. In 1910, he was elected professor to the chair of hygiene at Moscow University, a position he held until his retirement in 1924. From 1924 to 1927, Orlov worked as a consultant and deputy director at the Sanitary and Hygienic Institute of the People's Commissariat of Health of the RSFSR. Orlov took an active part in the work of the Academic Medical Council of the People's Commissariat of Health and was one of its most active members in developing routine problems in the field of public catering. The scientific works of Orlov (more than 30) relate chiefly to the methodology of sanitary and hygienic research of food products and everyday commodities (these works were published in the reports of the Moscow Sanitary Station (1894–1905), edited by Erisman, Bubnov, and Orlov himself).

All these works are experimental in nature and provide scientific illumination of the practical applicability of a particular analytical method. Orlov's dissertation, "Groundwaters of the City of Moscow and its Cemeteries" (Moscow, 1905), illuminates the question of the influence of sewerage on the processes of self-purification of urban soil and groundwater and contains valuable material for subsequent researchers of the same question. ORNITHODORUS, a genus of ticks of the family Argasidae, superfamily Ixodoidea. The body is thick, without a sharp border on the sides between the dorsal and ventral sides. They inhabit hot and warm countries. In the USSR, they are found in the Caucasus (up to Makhachkala) and in Central Asia (to the southern part of Kazakhstan). Ornithodorus moubata

Figure 1. Ornithodorus moubata: I—male; II—female; a—from the ventral side; b—from above. (Fig. 1) (tropical Africa) lives in native huts and along caravan routes, burying itself in dust or crawling into cracks of buildings during the day. It attacks mammals, birds, and humans and sucks their blood. In humans, it is the vector of African relapsing fever (Treponema Duttoni). Ornithodorus Savignyi is rarer in Africa and India. In the USSR, Ornithodorus papillipes (Fig. 2) is found; female 7.8–8.2 × 4.3–5 mm, male somewhat smaller. Dark gray in color, with shagreen-textured chitin. Ornithodorus lahorensis (Fig. 3) is much larger: its body dimensions in females are up to 11 × 6.2 mm. The chitin of the integument has a star-like structure. Ornithodorus papillipes lives in livestock buildings, yurt tents, houses, and porcupine lairs. It attacks hosts at night. It sucks blood for a long time (up to 40 minutes). The blood-sucking procedure

Figure 2.

Figure 3.

Figure 2. Ornithodorus papillipes—female from the ventral side: 1—rostrum; 2—coxa; 3—coxal fold; 4—lateral notch of the body; 5—anus; 6—postanal furrow; 7—anomarginal furrow. Figure 3. Ornithodorus lahorensis—female from the ventral side: 1—coxal fold; 2—coxa; 3—anus; 4 and 6—discs corresponding to muscle attachment sites; 5—anomarginal furrow. is painless for humans. A hemorrhagic papule—a characteristic sign of an Ornithodorus papillipes bite—rapidly develops on the skin at the site of the injection. It overwinters not on animals, as it is quite resistant to cold. It is the vector of the causative agent of Central Asian tick-borne relapsing fever—Spirochaeta sogdiana (Latyshev, Moskvin, Nicolle, Anderson). Infection occurs through the tick's saliva when it sucks human blood (Moskvin, Pavlovsky). In the nymph stage, Ornithodorus lahorensis stays in winter on hosts—camels, sheep, cows, and other animals. In spring, it drops off them and molts into the imago. They live in cracks of walls in livestock buildings. The development cycle of Ornithodorus lahorensis is: egg, larva, nymph I, nymph II, imago. Ornithodorus lahorensis is attributed the ability to spread Persian relapsing fever; Pavlovsky's experiments led to negative conclusions, as it was not possible to obtain infection with relapsing fever in guinea pigs by feeding nymphs or adult ticks on them. From other Ornithodorus of the USSR and the adjacent zone of Persia are known: Ornithodorus Kholodkovskyi (Central Asia), Ornithodorus canestrinii (Tehran, Tash-Burun), Ornithodorus talaje (Armenia), Ornithodorus talaje var. coniceps (Aral Sea?). In addition, there are new species living on various wild animals (described by Pavlovsky).

Questions of the prevention of tick-borne relapsing fever in the USSR are resolved along the lines of protecting humans from Ornithodorus papillipes bites (bed mosquito nets, avoiding overnight stays in mud-brick buildings of the native type, placing bed legs in cans with water and kerosene; see also Relapsing fever). Among the control measures against the tick itself, chloropicrin is indicated (Latyshev and Troitsky), the dose of which at a concentration of 1:100,000 (10 cm³ per 1 m³ of premises) kills the ticks.