Mosquito-Borne Viruses
4 out of 5 diseases transmit through Aedes Aegypti mosquitos, which are native to Africa.
Yellow Fever transmits through both Aedes Aegypti and Haemagogus spp., native to the Americas.
West Nile Virus transmits through Culex spp.
Dengue, Zika, and Chikungunya cause very similar symptoms. Often cannot distinguish them without PCR or Serology.
Additionally, they have a short incubation period and acute phase of illness: On in a week, gone in a week.
Symptom Profiles
| Zika | Dengue | Chikungunya | |
|---|---|---|---|
| Fever | + | +++ | +++ |
| Rash | +++ | + | ++ |
| Conjunctivitis | ++ | - | - |
| Arthralgia | ++ | - | +++ |
| Myalgia | + | ++ | + |
| Headache | + | ++ | ++ |
Dengue
Flavivirus.
Severe Myalgias gives Dengue the name “breakbone fever.” Additionally, the headache is generally retroorbital (behind the eyes).
Progression
Febrile Period (1-3 days): Normal fever, headache, myalgia, rash
Critical Period (3-5 days): Hematocrit increases, platelet count decreases. Abdominal pain, vomiting, hepatomegaly.
Severe Period (5+ days): Shock, Bleeding, 3rd spacing (edema of interstitium), organ dysfunction
Diagnosis
PCR if presenting within 1st week. Otherwise, IgG/IgM serology is required.
Treatment
Acetaminophen as NSAIDs will result in uncontrolled bleeding.
There is a vaccine available for teenagers with prior history of infection.
Chikungunya
Alphavirus.
The most severe symptom is arthralgia and arthritis.
Diagnosis
PCR if presenting within 1st week. Otherwise, IgG/IgM serology is required
Treatment
Use NSAIDs if certain it is not Dengue. Otherwise, treat with acetaminophen.
Zika
Flavivirus.
The key symptom is conjunctivitis which is unique to Zika. Also important to note is that Zika can be sexually transmitted.
Congenital Zika Syndrome: Microcephaly and neurological developmental issues.
Diagnosis
PCR if presenting within 2 weeks. Otherwise, only IgM serology is available.
Yellow Fever
Incubates for 3-5 days.
Sylvatic transmission cycles between humans, mosquitos, and monkeys, while urban transmission cycles between only humans and mosquitos.
Progression
Febrile phase: Fever, Headache, Myalgia (similar to above two)
Intoxication phase: Seizures, renal failure, Hemorrhage, Acute hepatocellular necrosis
Treatment
Prevention only. There is a live, attenuated vaccine available.
West Nile
Flavivirus. Has a transmission cycle between birds, mosquitos, and humans.
Symptoms include fever, malaise, and rash. In rare cases, it can progress to a neuro-invasive disease which can result in acute ascending flaccid paralysis and aseptic meningitis.
Treatment
Prevention only. No vaccine either.
