A mosquito bite left a bump on me. Will I get dengue or AIDS?

It is well known that the flying height and distance of mosquitoes are limited. Theoretically, mosquito-borne diseases will not become widespread in areas that exceed their maximum flying distance and maximum flying height. However, the reality is the opposite. There are always smart mosquitoes that use airplanes, ships, cars, trains and other means of transportation to have sex with mosquitoes of the opposite sex in new populations in new places and complete the reproduction process. Therefore, all pathogens that can proliferate in their bodies, such as dengue fever, malaria, epidemic encephalitis B (Japanese encephalitis), Zika virus disease, yellow fever, chikungunya fever, and filariasis, will spread along with them [1]. Of course, in addition to these, patients and latently infected persons are also important sources of transmission.

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What diseases can be spread by mosquito bites?

Mosquitoes can spread dengue fever, malaria, Japanese encephalitis, Zika virus disease, yellow fever, chikungunya fever, filariasis and many other diseases through their bites [1]. Taking dengue virus as an example, the main vector of dengue virus in Chongqing is Aedes albopictus, also known as the "flower-legged mosquito". Dengue virus enters the human body through mosquito saliva, and its transmission process is as follows:

After the Aedes albopictus mosquito sucks the blood of a dengue patient or latently infected person, the virus replicates in the mosquito's intestines or other organs and infects the salivary glands. After an external incubation period of about 8-10 days, the virus-carrying mosquito bites the next person and, at the same time, secretes saliva to bring the virus into the human body. After a possible incubation period of 1-14 days, the virus replicates in the target organ, infects white blood cells and lymphoid tissue, and enters the blood circulation. From about 1 day before the onset of the disease to 5 days after the onset of the disease, the patient is in the viremia stage and becomes a new source of infection. In addition, infected mosquitoes can spread the virus throughout their lives and can also pass the virus to their offspring through eggs. After 1-2 weeks, more new "poisonous mosquitoes" can be raised. And studies have shown that patients infected with dengue fever are also attracting more mosquitoes to bite. The increased body temperature, exhaled carbon dioxide, and chemicals released by the body all attract mosquitoes. Under the influence of multiple factors, dengue fever can easily cause large-scale infection, seriously threatening the health of residents. If you suddenly develop a high fever, your body temperature can quickly rise to above 39°C, last for 2-7 days, and you have symptoms such as headache, orbital pain, muscle and joint pain, rash, fatigue, nausea, vomiting, swollen lymph nodes, especially if you have a recent travel history to dengue fever-endemic areas, it is recommended that you go to the hospital for examination and treatment in time.

If you are bitten by a mosquito that has sucked the blood of an AIDS patient, will you be infected?

No! The reason why mosquitoes can spread diseases is that those pathogens can first survive in the mosquito's body, and secondly, they can reproduce. After the mosquito sucks blood, it completes the reproduction and mass proliferation process in the mosquito's body, and migrates to the mosquito's saliva or beak, thus causing infection when it bites next time. However, the AIDS virus (Human Immunodeficiency Virus, HIV) cannot survive stably for a long time in the mosquito's body. After the mosquito sucks the blood of an AIDS patient, the virus will be digested in the mosquito's stomach and cannot continue to survive or reproduce. From the perspective of the mosquito's life characteristics, a mosquito will not suck the blood of a person immediately in a short period of time, regardless of whether it sucks enough blood at one time. Otherwise, the agglutination reaction between different blood types is enough to cause it to produce a large amount of clots and cause death. In addition, to spread AIDS, a very large amount of virus is required. The amount of blood remaining in the mosquito's mouth is very small, far from the amount of virus required for transmission. According to research, it takes thousands of mosquitoes to bite an AIDS patient at the same time to have enough virus to pass on to the next person bitten, and this situation almost never happens. Therefore, although HIV can be transmitted through blood, mosquito bites are unlikely to be a transmission route leading to new infections.

References:

[1] Hou Haiguang, Li Peiyu, Qin Na, et al. Analysis of mosquito density monitoring results in Tianjin from 2015 to 2018[J]. Medical Animal Control, 2020, 36(08): 798-800.

Source: Chongqing Science Writers Association

Author: Li Mei, deputy chief technician, Zhang Huizheng, deputy chief technician, Chongqing Public Health Medical Treatment Center; Zou Jingbo, chief technician, Chongqing Yongchuan District Center for Disease Control and Prevention

Nuclear expert: Li Hanbin

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