**16. Conclusion**

administered at 12 months of age. In the case of outbreaks, it can be administered as early as 6 months of age [71]. Yellow fever vaccine is a live vaccine, so theoretically it should not be given to pregnant women or to immunosuppressed individuals. A single fatal adverse reac‐ tion (encephalitis) has been reported in an immunosuppressed individual with HIV/AIDS.

Vector control is defined as measures of any kind directed against a vector of disease and intended to limit its ability to transmit the disease [72]. In yellow fever control specifically in

The risk of yellow fever transmission in urban areas can be reduced by eliminating potential mosquito breeding sites and applying insecticides to water where they develop in their im‐ mature stages [13]. Indeed, source reduction is one of the key components in the vector con‐ trol programme since the target is exceptionally specific unlike adult control [73]. Vectorcontrol strategies that were once successful for elimination of yellow fever from many regions have faltered, leading to reemergence of the disease[3]. Application of spray insecti‐ cides to kill adult mosquitoes during urban epidemics, combined with emergency vaccina‐ tion campaigns, can reduce or halt yellow fever transmission and the "buying time" for

Historically, mosquito control campaigns successfully eliminated *Ae. aegypti*, the urban yel‐ low fever vector, from most mainland countries of central and South America. However, this mosquito species has re-colonized urban areas in the region and poses a renewed risk of urban yellow fever. Mosquito control programmes targeting wild mosquitoes in forested areas are not practical for preventing jungle (or sylvatic) yellow fever transmission [13]. The period between about 1950 and the 1970s was one of the complacency about the control of YF, probably arising from the feeling that YF vaccination had solved the problem. *Ae. aegypti* control was reduced and overall disease record keeping appears to have diminished. For the period 1960–2005, only 110 yellow fever points were recorded in Africa and 171 in South America. In both regions, these records more or less fall within the same areas of risk shown for the first half of the last century, although there is a noticeable lack of new records in Cen‐

*Ae. aegypti*, has adapted their peak biting activities in the early evening and early morning, when their potential hosts are less protected. Mosquito repellents have a unique role under these conditions. Easily accessible, safe and effective mosquito repellents provide a valuable supplement to IRS and ITN use, and in areas with day-biting, exophagic vectors, this may be the only option for reducing the level of disease transmission [74]. The core principle of re‐ pellents usage is that they are extremely useful and helpful whenever and wherever other personal protection measures are impossible or impracticable [75]. Insect repellents are ex‐

tral America and proportionately more cases within the Amazon basin [33].

certain circumstances, mosquito control is vital until vaccination takes effect.

**15.2. Vector control**

222 Encephalitis

*15.2.1. Source reduction*

*15.2.2. Insect repellents*

vaccinated populations to build immunity [13].

YF has played a central role in the history of infectious diseases. It was the first disease to be demonstrated to be transmitted by an arthropod, one of the first diseases to be shown to be caused by a virus, and one of the first infectious agents to be controlled by the development of a live vaccine [80]. Indeed, the challenges and dangers posed by yellow fever remain for‐ midable. It is mainly contributed by the global warming, land use changes, uncontrolled population growth, unchecked urbanization, rural - urban migration, international trade, conflict and civil disruption. Although the tools for diagnosis, vector control, vaccine and surveillance are available, their implementation is extremely poor or inadequate in many of the resource-constrained YF endemic countries. In addition, the global-warming concomi‐ tant effect immensely contributed to the high reproduction rate and the capacity of insect vectors to establish and to adapt to new environmental conditions.

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Certainly, the present scrutiny clearly suggests that the yellow fever encephalitis is emerg‐ ing and resurging as a global public health threat in a changing environment. It contributes to remain as a disease of increasing epidemic risk. Therefore, the following issues such as high population density, development of peri-urban areas with rural interfaces, urban con‐ struction in forest areas, inconsistent vector control programme, spread of new pathogens, inadequate coverage and short-supply of yellow fever vaccine, must be addressed effective‐ ly for the betterment of humankind, eventually to build a yellow fever free world in the near future.
