Effects of Pathogen-Vector Interactions on the Transmission of Dengue Virus

Transmission Cycle

Figure 4. Transmission cycle of dengue virus between human hosts and mosquito vectors.[10]

The DENV transmission cycle begins when an infected mosquito bites a human or nonhuman primate host. The Host begins to experience symptoms four to seven days post-infection with symptoms usually lasting three to ten days after which there is about a three week recovery period [8]. The virus initially replicates in target organs like the liver, spleen, and thymus but eventually makes its way to the lymphatic system where it replicates in lymph tissue and white blood cells. The lymphatic system serves as a gateway to the bloodstream where the virus continues to replicate and can potentially infect the endothelial cells of the circulatory vasculature. Eventually virus titers are high enough in the host blood for disease transmission to occur. For a period of about five days, just before symptoms appear, the virus is transmissible to a new mosquito vector through an infected blood meal.

After being taken up in an infected blood meal by a mosquito DENV replicates in the midgut of the insect and infects its hemocoel (body cavity). From the hemocoel, the virus eventually infects the salivary glands. Once virus titers are high enough in the salivary glands the mosquito can infect a new susceptible host when it goes for another blood meal [4]. The length of time required for virus to reach the salivary glands of a mosquito after the ingestion of an infected blood meal is about eight to ten days depending on both viral and host factors [8]. The delay between ingestion of an infected blood meal and infection and replication of DENV in the salivary glands influences the course of epidemics and plays a role in competition between DENV strains.