Disease Vector Awareness and Action, by K.B., M.D.

I am writing this article to share with our dear readers the information from several news articles featuring illnesses secondary to disease vectors and also spread due to immigration to the United States or international travel to other countries. It is a broad topic that I will condense for our readers in hopes of increasing not only awareness but also instructing in means of protection and treatment. Disclaimer: I am neither prescribing medicine nor dispensing medical advice. Anything that you choose to do as a result of reading this article is your own responsibility. Always seek out treatment and advice from your own medical professional who is aware of your personal medical health and the risks in the area of country in which you live or have traveled to.

Disease Vectors

What is a disease vector? It is any living agent that carries and transmits infectious disease to another living organism, such as humans. What are types of agents? There are arthropods such as mosquitos, fleas, and ticks. There are also mammals such as dogs, bats, raccoons, skunks, etc. Why the concern? As society declines and poverty rises, sanitation often deteriorates with the subsequent rise in populations of vermin.

Allow me to give you an up close and personal example. A new neighbor moved next door to our family and decided to just start heaving cardboard boxes, mattresses, and other assorted trash into the corner next to our fence. What happened? Rats soon infested the conglomeration and we had to contact the city health department as the neighbor declined to act upon our request to clean it up. Why contact the health department? Rats carry fleas which experience has shown may be infected with many diseases such as murine typhus and bubonic plague. Surely our fair American cities are not overrun with vermin……yet? Oh yes, they are. New York City is estimated to have 3 million rats and the situation is so dramatic that tours now wind through certain neighborhoods in order to entertain tourists with the grossness of the situation. “Come to the Big Apple and see our famous rats!” What a great ad that would make. (Sarcasm intended.)

Murine (Flea-borne) Typhus

Murine typhus is caused by the bacteria Rickettsia typhi which is transmitted to humans most commonly by the bite of the rat flea or cat flea. The flea becomes infected for life when it bites an infected animal such as a rat, possum, or cat. The flea defecates infected excrement (aka flea dirt) when it creates a bite wound. The bacteria in the excrement is then rubbed into the wound. Another means of infection is if flea dirt is inhaled or rubbed into the eyes. Is this happening in the U.S.? Definitely yes. In fact, the Center for Disease Control is concerned that it is significantly increasing. Locations include southern Texas, California, and Hawaii, but it can occur almost anywhere else. Recently three people *died* of it in L.A. county and I recall reading about employees in City Hall becoming infected. You don’t just have to be homeless and living in an alley to contract it. New York City with its huge rat population may be next.

Symptoms of murine typhus are nonspecific and flu-like including headache, fever, chills, muscle aches, and pains. Half of patients develop a rash on the torso by around day 5. Treatment is doxycycline 100mg orally twice daily for adults until improved, afebrile for 48 hours, and for a minimum of 7 days. The first dose however should be a loading dose of 200mg. Cases are fatal in less than 1 % with antibiotic treatment (the sooner treatment begins the better) and 4% without treatment. Question the patient for a history of petting stray cats or exposure to possums, rats, fleas, or rooms with lots of flea dirt to inhale or rub into the eyes. Prevention consists of avoiding contact with fleas and keeping them off pets plus avoiding wild animals. Means of rodent control include rat poison, traps (glue or snap), and sealing up openings to buildings.

Dengue

Dengue, also known as Break-bone fever, is spread by the bite of the Aedes mosquito which seeks blood meals early in the morning and in the evening. Dengue cannot be spread from person to person but an individual ill with dengue can spread it to a feeding mosquito which is then infectious for the remainder of its life and can spread this virus to other humans. Dengue is usually contracted in tropical countries but *local* spread has occurred in Florida, Texas, Arizona, and Hawaii. Symptoms include severe headache with pain behind the eyes, high fever, and muscle, bone and joint pains. Skin rash develops in 50 to 80% of patients. This rash may have up to three different stages. It presents initially as diffuse redness, may progress later to a measles-like pattern of red spots, and may finalize as islands of white in a sea of red. Travelers returning to the U.S. or immigrants may develop dengue upon arrival depending on the timing of the infected bite with an incubation period of 3 to 15 days but more likely 7 to 10 days. Most cases respond to supportive treatment consisting of rest and fluids, oral or intravenous, with only 5% of patients developing a severe hemorrhagic form.

Avoidance is by eliminating mosquito bites through the use of intact window and door screens, insect repellants, and the wearing of long loose fitting sleeves and slacks when outside. DEET is not recommended for children less than two months of age plus DEET should not be applied to the hands of children. Standing water in old tires, planters, bird baths, animal dishes, etc should be dumped weekly to prevent the laying and hatching of mosquito eggs. Mosquito nets should be employed where screens are unavailable. Holes in screens should be repaired promptly.

Malaria

*Locally acquired* cases of malaria have recently been reported- one in Maryland, one in Texas, and
seven in Florida. The cases in Florida and Texas were of a type that is normally seen in South America, yet it was acquired locally. Was this due to immigration or spread from other travelers to local mosquitos which became infected and then bit local residents? Will we see a resurgence of mosquito-borne diseases as society declines? Malaria was endemic in the United States until the 1950’s and had reached as far north as Cleveland. Symptoms include fever, sweats, chills, headache, nausea, and vomiting. Yellow fever was another mosquito-borne disease that afflicted America. In 1793, a yellow fever outbreak hit Philadelphia resulting in the deaths of 5,000 people over a period of 3 months. Congressional and executive officials fled the city and doctors were unaware at that time of the role that mosquitoes played in the transmission of the disease. May our authorities remain vigilant, control mosquito populations, and promptly report any suspicious disease outbreaks.

Leprosy

Leprosy, also known as Hansen’s disease, raises frightening images for those of us who have viewed the movie Ben Hur. What many do not know is that the armadillo is a reservoir for Mycobacterium leprae the organism that causes this chronic infectious disease of the skin and peripheral nervous system. It is thought that the nine-banded armadillo carries M. leprae due to its low body temperature and can transmit it to humans. I would suggest that one avoid handling this animal, alive or dead. The Food and Drug Administration declares that it is safe to eat these “Hoover hogs”, but I think I’ll skip it unless facing death from starvation. It is usually not possible to see the leprous skin lesions on the armadillo due to its armor. Humans usually, however, contract the disease from other infected humans through extended contact with respiratory droplets, also not all who are exposed to the disease develop it. Those with reduced immune function such as the poor and malnourished are at greater risk. A patient is considered to have leprosy if they have the skin lesions plus sensory loss or a skin smear positive for M.leprae. Fortunately, leprosy is now treatable with multidrug therapy (dapsone, rifampicin, and clofamzimine) which renders the patient no longer infectious after 72 hours.

Unfortunately, leprosy is now endemic (regularly occurring) in central Florida and case numbers are rising. While some cases are due to contact with immigrants from countries with leprosy, other cases lack any of the traditional risk factors. Officials are considering the possibility of environmental reservoirs in central Florida. Another state, Arkansas, was concerned in 2008 that they were at risk for a surge of cases. Why? Immigrants from the Marshall Islands were sources of M.leprae.

Bedbugs May Transmit MRSA?

You are on a business trip and wake up the next morning with itchy red bumps on your exposed face, neck, and arms. You’ve been visited in the night by bedbugs who obtained their blood meal from you. How to avoid them in the future? First, check online at “Bedbug Registry” to see if the hotel that you are considering staying at is listed as infested. Next, when you check in and go to your room, place your bag(s) on the tile floor of the bathroom while you inspect the room. Check the headboard, mattress seams, and night stand for any dark 4 to 5mm sized insects or dots of blood or dark spots of insect feces. If present, request another room farther away.

The bites may vary in size from 2mm up to 2 cm depending on your body’s reaction. Unpleasant itching and swelling may be treated with topical or oral antihistamines and or corticosteroids. (Beware of the sedative effect of some antihistamines if planning to drive.) Upon arriving home, leave your luggage (potentially infested) in the garage and place all clothing in the washer and then dryer on high heat for 30 to 45 minutes.
There is concern that bedbugs might be able to transmit MRSA (methicillin-resistant Staphylococcus aureus) which can result in serious or even fatal infections. In two out of three studies, bedbugs feeding on MRSA infected blood through a membrane were later able to transmit it through another membrane during feeding. There is need for further investigation to confirm or refute this potential danger.