Infectious Disease

 

Amebiasis:

  • Acute amebic colitis has a gradual onset presenting with a 1- to 2-week history of abdominal pain, diarrhea, and tenesmus. Stool samples, which are watery and contain blood and mucus, have little fecal material. Fever is noted in only a minority of patients.
  • Lower quadrant abdominal tenderness may be noted.
  • Chronic amebic colitis is clinically similar to inflammatory bowel disease. Recurrent episodes of bloody diarrhea and vague abdominal discomfort develop in 90% of patients with chronic amebic colitis who have antibodies to E histolytica. Consider amebiasis in all patients in whom inflammatory bowel disease is suspected before administering steroids.
  • A biopsy of colonic ulcers reveals trophozoites in patients with amebiasis.
  • Amebic liver abscess is the most common form of extraintestinal amebiasis
  • Amebic liver abscess appears with an abrupt onset of high fever; a cough; and dull, aching, constant abdominal pain in the right upper quadrant or epigastrium, usually lasting fewer than 10 days
  • Patients with acute amebic colitis may have lower quadrant abdominal tenderness.
  • Fever is noted in only a minority of patients.
  • Dehydration is uncommon.
  • Occult blood is nearly always present in stools.

DX:

  • Enzyme immunoassay (EIA): This is the best test for making the specific diagnosis of E histolytica in the clinical setting                                  Rectosigmoidoscopy and colonoscopy may provide useful diagnostic information in intestinal amebiasis.                                                                                 Consider rectosigmoidoscopy and colonoscopy before using steroids in patients in whom inflammatory bowel disease is suspected

TX:

 

Botulism:

Botulism is a paralytic disease caused by the neurotoxins of Clostridium botulinum and in rare cases. These gram-positive spore-forming anaerobes can be found in soil samples and marine sediments throughout the world.

With a lethal dose to humans of less than 1 mcg, botulinum toxins are the most poisonous substances known and pose a great threat as an agent of biological warfare.

The term botulus is derived from the Latin word for "sausage." An outbreak of clostridial "sausage poisoning" in Europe in the late 1700s was responsible for many deaths.

The first form, food-borne botulism, follows the ingestion of preformed toxin in foods that have not been canned or preserved properly.

Wound botulism, caused by systemic spread of toxin produced by organisms inhabiting wounds, is associated with trauma, surgery, subcutaneous heroin injection, and sinusitis from intranasal cocaine abuse.

Infant botulism results from intestinal colonization of organisms in infants younger than 1 year.

home-processed foods are responsible for most (94%) outbreaks of food-borne botulism in the continental US. In fact, of the 6% of outbreaks caused by mass-produced commercial foods, most cases were attributed to consumer mishandling of commercial products

 the ingestion of honey has been identified as a strong risk factor for the disease

 

SXS: Dozen D's: dry mouth, diplopia, dilated pupils, droopy eyes, droopy face, diminished gag reflex, dysphagia, dysarthria, dysphonia, difficulty lifting head, descending paralysis, and diaphragmatic paralysis.

  • Infant botulism.
  • A prominent and common sign of the disease is constipation (defined as 3 or more days without defecation). Other clinical features include listlessness, lethargy, difficulty in sucking and swallowing, hypotonia, weak cry, poor feeding, pooled oral secretions, generalized muscle weakness, and poor head control, which gives the infant a characteristic floppy appearance

DX:

  • For food-borne botulism, toxin is found in serum samples 39% of the time and in stools 24% of the time.
  • Organisms are found in cultures of stool samples 55% of the time.
  • Stool cultures generally are more sensitive than toxin detection for specimens obtained later (>3 d postingestion) in the course of illness.

TX: Trivalent equine botulism antitoxin -- CDC recommends administration of 1 vial of antitoxin for adult patients with botulism as soon as diagnosis is made, without waiting for laboratory confirmation

 

Cholera:

  • Derives from the Greek word for the gutter of a roof, comparing the deluge of water following a rainstorm to that of the anus of an infected person.         Cholera is an ancient disease caused by Vibrio cholerae
  • Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacteria Vibrio cholerae. The infection is often mild or without symptoms, but sometimes it can be severe.

Cholera is a toxin-mediated disease

V cholerae is a saltwater organism, and its primary habitat is the marine ecosystem where it lives in association with plankton

 Most of these cases occurred in Louisiana

Cholera epidemics now occur regularly in Africa, Asia, and South America

 

SXS:                                                                                                                   Profuse watery diarrhea is a hallmark of cholera “Rice Water Stools”

·                                                                                 V cholerae does not elicit an inflammatory response, and cholera stool contains few leukocytes and no erythrocytes.

·                                                                                 Because of the large volume of diarrhea, patients with cholera have frequent and often uncontrolled bowel movements.

·                                                                                 Patients experience abdominal cramps, probably caused by distention of loops of small bowel as a result of the large volume of intestinal secretions.

·                                                                                 Vomiting is a prominent manifestation of illness

·         Decreased intravascular volume is manifested by tachycardia, absent or barely palpable peripheral pulses, and hypotension

·         Acidosis in cholera is a result of bicarbonate loss in stools, accumulation of lactate because of diminished perfusion of peripheral tissues, and hyperphosphatemia.

DX:

Cholera is diagnosed by isolating the cholera bacterium, Vibrio cholerae, from stool or vomit, or by finding evidence in the blood of the recent production of antibodies against cholera.

  • Direct microscopic examination: V cholerae is a gram-negative curved bacillus that is motile by means of a single flagellum. Laboratory diagnosis is required not only for identification but also for epidemiological purposes.

TX:

IV fluids and Doxycycline or tetracycline

 

Staph Food Poisoning

Usually symptoms start within several hours (2-4) of ingestion of potentially contaminated foods, beginning with significant nausea, vomiting, and intestinal cramping, followed by urgency and profuse watery nonbloody diarrhea

Classic symptoms are an abrupt onset of intense nausea, vomiting, cramping abdominal pain, and diarrhea, which incapacitate the patient. Most cases are self-limited and resolve in 8-24 hours.

  • If the route of entry of the toxin is GI, patients may appear dehydrated and, depending on the severity of nausea, may complain of acute abdominal cramping and diarrhea
  • .Physical examination may reveal hypotension, tachycardia, hyperperistalsis, and diffuse non localizing abdominal pain. Any stool or diarrhea is hemoglobin negative, barring other pathology.

TX

IV fluids and antiemetics (Phenergan, Reglan, Zofran)

 

Giardiasis

Giardiasis is caused by ingestion of Giardia cysts

Giardiasis also may be contracted through the ingestion of contaminated water

is a major diarrheal disease found throughout the world. Giardia lamblia, its causative agent,

·          most commonly identified intestinal parasite in the United States.

Most infections result from fecal-oral transmission or ingestion of contaminated water. Contaminated food is a less common etiology

·         The majority of patients experience a more insidious onset of symptoms, which are recurrent or resistant.

·         Stools become malodorous, mushy, and greasy. Watery diarrhea may alternate with soft stools or even constipation. Stools do not contain blood or pus because dysenteric symptoms are not a feature of giardiasis.

  • Miscellaneous: Unusual presentations include allergic manifestations such as urticaria, erythema multiforme, bronchospasm, reactive arthritis, and biliary tract disease

DX:

  • Stool examination
  • At least 3 stools taken at 2-day intervals should be examined for ova and parasites.

 

TX:

  • Metronidazole (Flagyl)
  • Nitazoxanide (Alinia)

 

Salmonellosis

  • The transmission of salmonellae to a susceptible host usually occurs by consumption of contaminated foods.
  • The most common sources of salmonellae are beef, poultry, and eggs
  • Improperly prepared fruits, vegetables, dairy products, and shellfish
  • Amphibian and reptile exposure is associated with approximately 74,000 Salmonella infections annually in the United States.
  • Recently, cats have also been implicated as a potential reservoir.
  • Nausea, vomiting, and diarrhea occur within 6-48 hours after ingestion of contaminated food or drink.
  • In most cases, stools are loose and bloodless. Salmonellae may rarely cause large-volume cholera-like diarrhea or may be associated with tenesmus.
  • The diarrhea is typically self-limiting and resolves within 3-7 days.
  •  Salmonellae may cause septic arthritis and osteomyelitis. The latter affects the long bones and typically occurs in patients with sickle cell disease

TX

 

 

 

 

 

 

Shigella

·         Shigellosis is spread by means of fecal-oral transmission. Other modes of transmission include ingestion of contaminated food or water, contact with a contaminated inanimate object, and sexual contact.

·         Vectors like the housefly can spread the disease by physically transporting infected feces.

·          The incubation period varies from 12 hours to 7 days, but typically it is 2-4 days, and it is inversely proportional to the load of ingested bacteria.

·         The host response to primary infection is characterized by the induction of an acute inflammation, which is accompanied by polymorphonuclear cell (PMN) infiltration, resulting in massive destruction of the colonic mucosa.

·         Gross pathology consists of mucosal edema, erythema, friability, superficial ulceration, and focal mucosal hemorrhage involving the rectosigmoid junction primarily.

  • Populations that are at high-risk for shigellosis include the following:
    • Children in daycare centers
    • Orthodox Jews
    • Native Caucasians
    • Persons in custodial institutions
    • International travelers
    • Homosexual men
    • Persons in homes with inadequate water supply
    • Sudden onset of severe abdominal cramping, high-grade fever, emesis, anorexia, and large-volume watery diarrhea. Seizures may be an early manifestation.
    • Abdominal pain, tenesmus, urgency, fecal incontinence, and small-volume mucoid diarrhea with frank blood may subsequently occur.
  • Physical examination during acute illness reveals a febrile ill-appearing child. Fever with a temperature as high as 39-40°C may be noted.
  • The patient's hydration status should be assessed carefully. Especially note dryness of the mouth, a lack of tears, decreased urine output, and loss of skin turgor.
    • In approximately 70% of patients with shigellosis, fecal blood or leukocytes (confirming colitis) are detectable in the stool. Fecal blood and leukocytes are present in 50% of patients.

TX:

1st line=Bactrim 2nd=Amoxicillin 3rd=Rocephin 4th=Azithromycin

Typhoid Fever

Typhoid fever, also known as enteric fever, is a systemic infection by Salmonella typhi

Typhoid fever is a severe multisystemic illness characterized by the classic prolonged fever, sustained bacteremia without endothelial or endocardial involvement, and bacterial invasion of and multiplication within the mononuclear phagocytic cells of the liver, spleen, lymph nodes, and Peyer patches.

Typhoid fever is potentially fatal if untreated.

SXS:

·         Fever

·         toxemia

·         delirium

·         abdominal pain, constipation

·         hepatosplenomegaly

TX:

·         Chloramphenicol (Chloromycetin)

·         Amoxicillin (Trimox, Amoxil, Biomox)

·         Trimethoprim and sulfamethoxazole (Bactrim DS, Septra)

·         Ciprofloxacin (Cipro)

 

Trichinosis

·         Infection is initiated by ingestion of viable larvae in raw or undercooked meat.

·         Specifically pork

·         Gastric action liberates the larvae, which are enclosed in intramuscular cysts. The liberated larvae develop into adults in the duodenum and jejunum, where they mate and bear offspring.

·         Eosinophilia develops in response to the presence of the worm

·         The US Department of Agriculture conducts periodic surveillance of farm-raised pigs. In a 1999 study, the major risk factor for seropositivity in tested pigs was access to live wildlife or wildlife carcasses.

·         Home raising of pigs, with feeding of raw garbage instead of grain, is still a common practice in a large part of the developing world.

·         Myalgia (75%) - Most commonly occurs in masseter, diaphragm, and intercostal muscles

·         Fever 38.5-40.5°C

·         Eosinophils

·         Creatine kinase is elevated in 90% of patients.

·         Parasite-specific indirect immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) titers

·         A muscle biopsy is the definitive diagnostic test

TX:

  • Prednisone
  • Vermox
  • Albendazole (Albenza)

 

Ascariasis

Ascaris lumbricoides is the largest of the common nematode (roundworm) infections of man

The prevalence of ascariasis is highest in children aged 2-10 years Intestinal obstruction, usually of the terminal ileum in children, is the most commonly attributed fatal complication

Symptoms

  • cough, dyspnea, wheezing, and chest pain
  • Jaundice, nausea, vomiting, fever
  • severe or radiating abdominal pain may suggest cholangitis, pancreatitis, or appendicitis

Stool examination for ova and parasites

TX:

Albendazole (Albenza) Mebendazole (Vermox)

 

Dengue Fever

Dengue, the most common arboviral illness transmitted worldwide Dengue viruses are transmitted by the bite of an infected Aedes mosquito Fever in persons with symptomatic dengue fever may be as high as 41°C.

      • Severe headache
      • Retro-orbital pain
      • Severe myalgias
      • Arthralgia
      • Characteristic rash
      • Hemorrhagic manifestations

 

      • Isolation of the dengue virus from serum, plasma, leukocytes, or autopsy samples

 

Hookworm Disease

  • Human hookworm infection is a common soil-transmitted helminth infection that is caused by the nematode parasites, Necator americanus and Ancylostoma duodenale.
  • The greatest number of cases occurs in the rural tropical and subtropical areas of China and sub-Saharan Africa, followed in number by India, South Asia, and Latin America.
  • During the first 1-2 weeks after a cutaneous infection, hookworm produces an intensely pruritic dermatitis at the site of infection termed ground itch.
  • Wakana syndrome occurs in people who have been infected with a large burden of A duodenale by means of oral ingestion. This syndrome is similar to an immediate-type hypersensitivity reaction characterized by pharyngeal itching, hoarseness, nausea, vomiting, cough, dyspnea, and eosinophilia.