Mosquito Borne Illnesses

One Nurse At A Time modules are intended to help nurses understand disease processes that are uncommon in our work practices at home.  They are intended to be practical guides and not exhaustive dissertations.  Education is a dynamic, ongoing process.  We value your input and comments on the content of this module.  Please feel free to write to OneNurseAtATime@gmail.com.

MOSQUITO-BORNE ILLNESSES:  DENGUE, CHIKUNGUNYA and ZIKA

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Dengue

A tropical paradise little known to westerners, the villages of southern Tamil Nadu, India were rife with the perfect environment to grow bananas and other tropical fruits. The nearly untouched beaches were beautiful in their abandonment. The humidity and warmth also made it a perfect breeding ground for the Indian elephant, flying foxes, and the mosquito. Subsistence fishermen filled the villages and were in dire need of medical care, so clinics were set up for the communities in most need by a local hospital run by the Sisters of the Holy Cross. 

The nuns ran the mission clinics with a clock-like precision not typical for developing areas. When they said it was time to eat, you ate. When it was time to leave, you’d better hustle to the bus. 

Occasionally during the oppressive heat of the afternoons, the head nun would disappear from the bustling clinics. I wondered where she had gone but was overwhelmed by the masses of people to be seen. What I didn’t know at the time was that she was suffering from headaches and fatigue from being infected with dengue fever. Fortunately, her case was uncomplicated, but not all are.

Dengue fever has been around for over 1000 years and spread with throughout tropical regions by global shipping in the 1700s. We rarely see Dengue in the US, but when you’re doing humanitarian work, you may find yourself in the middle of an outbreak.  

Dengue is a mosquito-borne Flavivirus and is most common in sub-tropical regions in urban and semi-urban areas. Dengue infects 400 million annually with 22,000 deaths.  It is carried and spread by the same Ae.aegypti or Ae.albopictus mosquito as Chkungunya, Zika and Yellow Fever.

Unlike the malaria-carrying Anopheles mosquito, this mosquito prefers fresh water to stagnant water to lay eggs. Overturned bottles, tires and other water-holding vessels should be drained and removed. The Dengue mosquito is a day-biter vs Malaria night-biter (often you’ll see them inside your vehicle in the mornings) and have striped legs!

Symptoms

Dengue can range from a mild, subclinical disease to a severe disease termed “Break-Bone Fever” causing death. Incubation period from bite to symptom onset is 4-10 days and symptoms last about a week. A critical phase can occur at Day 3-7 when fever drops below 38C/100F and severe complications occur due to plasma leakage. 

Uncomplicated dengue symptoms:

  • Musculoskeletal pain
  • Headache and eye pain
  • Lymphadenopathy
  • Nausea/vomiting
  • Rash (measles-like)
  • High fever (40C/104F)

 

WARNING SIGNS of SEVERE DENGUE:

  • Bloody emesis
  • Severe abdominal pain
  • Persistent vomiting
  • Tachypnea
  • Bleeding gums
  • Restlessness and fatigue

 

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Diagnosis

Normally, in low resource/field settings, you will have rapid tests which take 20 minutes for results. Clear instructions are included in the packaging.  If you do not have blood diagnostic tests available, the tourniquet test is one way to help differentiate dengue from other acute illnesses.

The tourniquet test is part of the new WHO case definition for dengue. The test is a marker of capillary fragility and it can be used as a triage tool to differentiate patients with acute gastroenteritis, for example, from those with dengue. Even if a tourniquet test was previously done, it should be repeated if 

 

  • It was previously negative 
  • There is no bleeding manifestation 

 

 

How to do a Tourniquet Test

  1. Take the patient’s blood pressure and record it, for example, 100/70. 
  2. Inflate the cuff to a point midway between Systolic BP and Diastolic BP and maintain for minutes. (100 + 70) ÷ 2 = 85 mm Hg 
  3. Deflate the cuff and wait 2 minutes. 
  4. Count petechiae below antecubital fossa. 
  5.   A positive test is 10 or more petechiae per 1 square inch.

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Prevention

VACCINE: Dengvaxia is a live attenuated vaccine approve for use in 2018 and may be used in people who have experienced previous dengue infections; however, it carries a risk of severe dengue in those who are seronegative at the time of vaccine and become infected (WHO, 2020).

Additional prevention:

  • Insect repellent
  • Permethrin-treated clothing and gear
  • Clothing (long sleeves, long pants) that minimizes skin exposure
  • Vector control – eliminate fresh standing water where mosquitos lay eggs
  • Mosquito nets over beds (this mosquito bites at dawn and before dusk) 
  • Window and door screens
  • Active virus surveillance

Treatments

As always, please refer to guidelines from the World Health Organization, MSF, or other point of care medical reference for the most recent medication guidelines.

The basics for uncomplicated dengue:

  • DO NOT USE ASPIRIN OR NSAIDS (ibuprofen, naproxen, diclofenac) due to bleeding risk
  • Tylenol (acetaminophen, paracetamol) can be used for fever and pain
  • Fluids including electrolytes (Oral Rehydrating Solution)

Severe dengue:

  • Monitor for warning signs of severe dengue fever
  • Fluid management
  • Rapid transfer to hospital for care and management of respiratory distress, hemorrhagic fever, and shock

CHIKUNGUNYA

The deluges that had drenched the mountains of Chocolá, Guatemala broke the long drought, but brought something new to the area: Chikungunya.  Mosquitos were thickly unavoidable in the wet air. The population complained of crippling pain in their hands and feet with fevers that would come and go. Some were bent up in pain nearly unable to move their extremities due to swelling. 

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Chikungunya is a disease that is endemic to West Africa, but has recently spread globally (even to Italy and the US). Chikungunya outbreaks occur in 2-20-year cycles, often long droughts, affecting 1/3 to 3/4 of the population.  It is spread by the same mosquito as Dengue which prefers fresh standing water for egg-laying.

 

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Typical incubation from bite to symptoms is 3-7 days.  It usually begins with abrupt onset of malaise and high-grade fever (>39C). Distal polyarthralgia of joints is a prominent feature in 70% of patients affecting wrists, fingers, ankles, knees, and elbows mimicking rheumatoid arthritis. Synovitis, joint effusions, and swelling of wrists, hands, and ankles are common. Macular and maculopapular rashes, sometimes with pruritis, are common at the onset of the virus. Headache, conjunctivitis, facial puffiness, gastrointestinal symptoms, and lymphadenopathy may occur.

While death is uncommon, severe cases can include hepatitis, renal failure, cardiovascular complications, meningoencephalitis, Guillain-Barré, seizures, and cranial nerve palsies.  Chronic  arthritis, arthralgia, tenosynovitis, frozen shoulder, plantar fasciitis, and new-onset Raynaud’s syndrome can occur in 25-75% of patients.

Diagnosis

Diagnosis is established with symptomatology, travel or residence in an area of outbreak, RT-PCR testing if available, and ELISA testing for those with symptoms >/= 8 days. There is no rapid field test, so diagnosis is usually made based on symptoms and geography. 

Differential diagnosis includes Dengue fever and Zika virus globally and Ross River virus in Australia. 

Prevention

There is no vaccine currently against Chikungunya.  Other prevention measures are the same as for Dengue: long sleeves/pants, permethrin, screens and nets, removal of sources of standing water.

Treatment

As always, please refer to guidelines from the World Health Organization, MSF, or other point of care medical reference for the most recent medication guidelines.

Treatment is the same as for Dengue:  Tylenol (paracetamol, acetaminophen) for fever, fluids, rest, hospitalization (if available) for severe cases.  

ZIKA

Zika first made international news in the lead-up to the 2016 Olympic Games in Brazil. The World Health Organization declared an international public health emergency as the disease spread through The Americas and beyond.  News of related microcephaly were scary for any mother at risk for infection and questions about the disease swirled through the media. Since that time, it’s dropped out of the spotlight, but what have we learned since then?

Zika was first discovered in 1947 in the Zika forest of Uganda where it remained with minimal spread until 2007 when it began a slow global spread. Zika is spread by the same mosquito as Dengue and Chikungunya, biting mostly during the daytime. Zika can be spread mother to fetus, through blood transfusions/organ transplants and through sexual contact.     

Symptoms

Zika is a predominantly mild disease, but if neurological symptoms occur, can be quite severe. The incubation period is thought to be 3-14 days, with most having little to no symptoms or mild symptoms lasting 2-7 days.

  • Fever
  • Conjunctivitis
  • Muscle and body pain
  • Malaise
  • Headache

Complicated Zika:

  • Microcephaly
  • Congenital abnormality
  • Preterm or stillbirth
  • Guillain-Barré syndrome
  • Neuropathy
  • Myelitis

Diagnosis

Labs must be acquired to differentiate between Zika and other Flaviviruses using serum, urine, or semen.

Prevention

There is no vaccine against Zika.

  • Insect repellent
  • Permethrin-treated clothing and gear
  • Clothing (long sleeves, long pants) that minimizes skin exposure
  • Vector control – eliminate fresh standing water where mosquitos lay eggs
  • Mosquito nets over beds (this mosquito bites at dawn and before dusk) 
  • Window and door screens
  • Active virus surveillance

Treatments

As always, please refer to guidelines from the World Health Organization, MSF, or other point of care medical reference for the most recent medication guidelines.

  • Rest
  • Tylenol (acetaminophen, paracetamol) can be used for fever and pain 
  • Fluids including electrolytes