# Distribution of Aedes aegypti and Aedes albopictus, and the current situation of dengue fever and chikungunya in Iran and neighboring countries: a review study

## TL;DR

This review study examines the spread of Aedes mosquitoes and the rise of dengue and chikungunya in Iran and neighboring countries, highlighting the risks posed by climate change and the need for surveillance.

## Contribution

The study provides updated insights into the distribution of Aedes mosquitoes and the epidemiology of dengue and chikungunya in Iran and surrounding regions.

## Key findings

- Local dengue transmission was reported in Iran for the first time in 2024 in southern provinces.
- Aedes aegypti and Aedes albopictus mosquitoes have established in multiple regions of Iran, increasing arbovirus transmission risks.
- Chikungunya remains undocumented in local mosquito populations in Iran, but potential cryptic circulation is suggested.

## Abstract

Aedes-borne diseases, such as dengue and chikungunya, are public health threats worldwide. Due to climate change and the expansion of Aedes mosquitoes, several countries are reporting the local transmission of Aedes-borne arboviruses. In 2024, Iran faced a significant rise in the number of imported dengue cases and the first local transmission of the disease in the southern provinces of Hormozgan and Sistan and Baluchistan. This review summarizes the latest data on the distribution of invasive Aedes mosquitoes and the epidemiological status of dengue fever and chikungunya in Iran and neighboring countries.

A comprehensive search was carried out on papers and reports concerning epidemiological records and studies on dengue fever, chikungunya, Aedes aegypti (Ae. aegypti), and Aedes albopictus (Ae. Albopictus), as well as the recent situation in Iran and neighboring countries since 2000. Meanwhile, the epidemiological trend and milestones of these arboviruses and their vectors in Iran and their last updates in neighboring countries were assessed.

In addition to Iran, at least nine neighboring countries including Armenia, Turkey, Iraq, Afghanistan, Pakistan, the United Arab Emirates, Oman, Qatar, and Saudi Arabia have reported the establishment of Ae. aegypti and/or Ae. albopictus mosquitoes. Local dengue virus transmission was reported in Iran, Pakistan, Afghanistan, Oman, the United Arab Emirates, and Saudi Arabia. However, the local circulation of chikungunya virus was only reported in Pakistan.

The establishment of Ae. aegypti in southern Iran (Hormozgan, Sistan and Baluchistan, Bushehr) and Ae. albopictus in northern/northwestern provinces (Guilan, Mazandaran, Ardabil, East Azerbaijan, Zanjan, Qazvin) has created distinct arbovirus transmission risks. Local dengue outbreaks in 2024 were exclusively reported in Ae. aegypti—infested areas (Chabahar, Bandar Lengeh), correlating with this vector's known efficiency in urban transmission. While chikungunya remains undocumented in local mosquito populations, serological evidence and recent report of the infected non-Aedes species suggest potential cryptic circulation. With climate models predicting habitat expansion for both vectors, Iran's emerging Aedes-borne diseases’ burden could escalate if no action is planned. This underscores the imperative for integrated surveillance targeting mosquito distributions, human case trends, and cross-border pathogen flow to mitigate outbreak risks.