Effect of Meteorological Factors on Hyalomma Species Composition and Their Host Preference, Seasonal Prevalence and Infection Status to Crimean-Congo Haemorrhagic Fever in Iran

Abstract

Background: The impact of environmental factors and host on Hyalomma spp. community structure and abundance in the main Crimean-Congo haemorrhagic fever (CCHF) foci of Iran is largely unknown.
 Methods: Biotic and abiotic factors, including host, temperature, humidity, altitude, Köppen-Geiger climate types, sea­son, and precipitation on Hyalomma spp. community structure and abundances in 11 provinces of Iran were investigat­ed. Additionally, the possible infection of ticks with CCHF virus was evaluated using reverse transcription PCR tech­nique.
 Results: Species analyses demonstrated the presence of Hyalomma anatolicum, H. marginatum, H. dromedarii, H. asi­aticum, H. detritum and H. schulzei in the study area. Hyalomma anatolicum was the dominant species in the southern and northern parts, whereas H. dromedarii was distributed mostly in central parts of the country. The highest tick infestation was recognized in hot season. Spatial variation in tick relative density was observed between habitat types where more ticks were collected in deserts, semi-deserts, and Mediterranean habitats. Except for H. dromedarii, which was more preva­lent on camel (P= 0.044), there were no significant variations in the frequencies of other Hyalomma species on different hosts. Hyalomma anatolicum, H. dromedarii frequencies had significant positive and negative asso­ciation with tempera­ture and precipitation respectively. Also humidity has positive impact on H. asiaticum frequency.
 Conclusion: Data presented here will help improve ecological models to forecast the distribution of Hyalomma spp. ticks, to evaluate the risk of CCHF and other tick-borne diseases, and to design proper vector control measures to sup­press Hyalomma populations in Iran.

Comparative Ecology of Hyalomma lusitanicum and Hyalomma marginatum Koch, 1844 (Acarina: Ixodidae)

“…In contrast, H. marginatum is able to support very cold temperatures and high humidity [86], so its likelihood of becoming established is higher. References: [11,16,30,32,[34][35][36]49,86,87].…”

“…are particularly sensitive to environmental parameters ( Table 5). H. lusitanicum is mainly distributed throughout the hot-summer Mediterranean climate (Csa) [35] whilst H. marginatum prefers hot desert climates (BWh) over hot-summer or warm-summer Mediterranean climates (Csa and Csb), cold desert climates (BWk) or cold semi-arid climates (BSk) [49].…”

“…Changes in global weather are also responsible for the settlement of newly introduced populations, whereas previous weather conditions did not allow them to overwinter. Although there is an alleged negative correlation between Hyalomma abundance and altitude [49], they are also expanding vertically; both species can be found from 0 m to 1000 m above sea level in Iberian Peninsula (personal observations) and H. marginatum has been collected by flagging at 2000 m above sea level in Turkey [107], while in the past they were rarely found at high altitudes [31,87].…”

Molecular detection of Dirofilaria spp. and host blood-meal identification in the Simulium turgaicum complex (Diptera: Simuliidae) in the Aras River Basin, northwestern Iran

“…Intrinsic factors, such as genetics and physiology, as well as behavioral traits, may govern an insect’s ability to acquire, support development, and transmit pathogenic agents. Extrinsic factors include the populations of the host reservoir and their activity patterns, climatic conditions, genetic variability in infectivity of pathogens, and even gut microorganisms [ 62 – 67 ]. Although blackflies are recognized as one of the most important medical and veterinary groups of arthropods due to their vector competence, there is a little information on their biology and ecology in Iran.…”

The effect of climate variables on the incidence of Crimean Congo Hemorrhagic Fever (CCHF) in Zahedan, Iran

“…Other studies reported that 46% of hyalomma spp. tick samples gathered in Iran were from desert climate, in Sistan and Baluchistan and Yazd provinces [ 33 ]. The Hyalomma tick is active in Iran from the beginning of spring and continues until the middle of summer [ 23 ].…”