Brucellosis and Typhoid fever

Dr. Shler Ghafour Raheem

BSc., MSc., PhD Medical Microbiology

shler.ghafour@tis.edu.iq

Brucellosis

• Brucellosis is a bacterial disease caused by various Brucellaspecies, which mainly infect cattle, swine, goats, sheep and dogs.

• Comes from drinking fresh milk from infected cows or goats, Itmay also enter the body through scrapes or wounds in the skin of persons whowork with sick cattle, goats, or pigs, or by breathing it into the lungs.

• The disease causes flu-like symptoms, including fever, weakness,malaise and weight loss.

• First discovered by a British physician and microbiologist David Bruceamong soldiers who served on Malta Island in 1887, it is known as Maltafever in the region.

Brucellosis is a chronic, life long infection in animal. Organisms localize in reproductive organ (male and female) and are shed in large numbers in milk, urine and the placenta.

The primary indicator of infection in animals are sterility or abortions.

Transmitted between animals in aborted tissues.

Brucellosis in humans is known as undulant fever, Mediterranean fever, Malta fever or Bangs disease.

Brucella species

Distinguishing features

• Small gram-negative rods,

• aerobic

• Zoonosis

• Facultative intracellular

• Serological confirmation of disease most common

• Culture is hazardous.

• Brucella melitensis (Sheep, Goat)

• Brucella abortus (Cattle)

• Brucella canis (dogs)

• Brucella suis (Pigs)

B melitensis is thought to be the most virulent and causes the most severe and acute cases of brucellosis; it is also the most prevalent worldwide.

Medically important species

Transmission

1) Ingestion:

• Raw milk & unpasteurized dairy products

• Rarely through undercooked meat

2) direct contact with an infected animal tissue.

3) Inhalation of infectious aerosols.

Note: The majority of cases are caused by ingesting unpasteurized milk orcheese from infected goats or sheep. Person-to-person transmission is rare.

Who is at Risk?

1) Occupational Disease• Cattle ranchers/ dairy farmers

• Veterinarians

• Abattoir workers

• Meat inspectors

• Lab workers

2) Hunters

3) Travelers

4) Consumers of unpasteurized dairy products

Pathogenesis

The organisms enter the body either by:

Ingestion of contaminated milk products or

Through the skin by direct contact in an occupational setting such as an abattoir.

They localize in the reticuloendothelial system, namely,

the lymph nodes, liver, spleen, and bone marrow.

Endotoxin is involved. No exotoxins are produced

Clinical finding

The incubation period of brucellosis normally is 1 to 3 weeks, but it can be

several months before showing any sign of infection

Clinical symptoms vary widely from patient to patient and ranging from

asymptomatic disease to severe illness. they may include recurrent fever,

sweats mainly in the night, sleeplessness, arthralgia, headaches, fatigue, malaise,

neuralgic symptoms and ache in joints, muscles , and-or back

Sweating (profuse)

Hepatomegaly

Brucella endocarditis and neurobrucellosis cause most deaths.

Diagnosis

1- Correct clinical history taking is essential to orientate thediagnosis (profession, food ingested, contact with animals and travel toendemic areas).

2- Cultural technique: Isolation of organism• Blood, bone marrow, CSF, pus, wound and urine. Bone marrow culture has

higher yield, sensitivity is usually 80-90%

• Subcultures are still advised for at least 4 weeks

3- Serological techniques

• Rose Bengal test can be used as a sensitive rapid screening test, positivetests to be confirmed by Standard agglutination test (SAT).

• 2-mercaptoethanol (2ME) test detects IgG, and titers higher

than 1:160 define active infection. A high IgG titer or a titer that is

higher after treatment suggests persistent infection or relapse.

IgM Ab indicate recent infection.

4- Molecular Diagnosis

Treatment

Adults: Rifampin plus doxycycline for 6 weeks. Thereis no significant resistance to these drugs.

Children: Rifampin plus cotrimoxazole

Prevention Pasteurization of milk,

Immunization of animals, and slaughtering of infectedanimals. There is no human vaccine.

Typhoid fever

• Typhoid fever is caused by Salmonella typhi bacteria. It israre in industrialized countries.

• Typhoid fever spreads through contaminated food andwater or through close contact with someone who'sinfected.

• Signs and symptoms usually include a high fever,headache, abdominal pain, and either constipation ordiarrhea.

GENUS: SALMONELLA

Genus Features

Gram-negative rods (Enterobacteriaceae)

Non–lactose fermenters

Motile

More than 2,400 serotypes of salmonellae

Salmonella typhi

Distinguishing features

• Gram-negative rods, highly motile with the Vi capsule

• Facultative anaerobe, non–lactose fermenting

• Produces H2S

• Species identification with biochemical reactions

• Sensitive to acid

Transmission

Typhoid fever is transmitted only by humans.

food handled by an individual who chronicallysheds the bacteria through stool or, lesscommonly, urine.

Hand-to-mouth transmission after using acontaminated toilet and neglecting handhygiene

Oral transmission via sewage-contaminatedwater or shellfish

Risk factors

• Worldwide, children are at greatest risk of getting the disease

• Work in or travel to endemic area

• Have close contact with someone who is infected

• Weak immune system such as use of corticosteroids or diseases such as HIV/AIDS

• Drinking water contaminated by sewage that contains S. typhi

Pathogenesis and Disease

Typhoid fever (enteric fever)

Organism ingested (requires large number if stomach acid is normal)

Infection begins in ileocecal region; constipation

common.

Salmonella reach M cells, then mesenteric lymph nodes and blood.

At 1 week: patients have 80% positive blood cultures; 25% have rose spots (trunk/abdomen)

S. typhi survives intracellularly and replicates in macrophages; resistant to macrophage killing due to Decreased fusion of lysosomes with phagosomes.

Released from the macrophages; the Vi capsular antigen withstands complement-mediated killing.

Biliary system (liver, gallbladder) is infected, organisms enter intestinal tract in bile.

The disease begins to resolve by the third week

By week 3: 85% of stool cultures are positive but severe complications can occur.

Diagnosis

• The diagnosis of disease requires laboratory testing.Blood and bone marrow were used for the isolation of thepathogen.

• Cultural technique

Blood culture is positive as follows:

1st week in 90%

2nd week in 75%

3rd week in 60%

4th week and later in 25%

Serological technique

• Serum agglutinins raise abruptly during the 2nd or 3rd week, it is +veby 10th day, but max. during 18-23rd day

• The widal test detects antibodies against O and H antigens

• The test is neither sensitive nor specific

2- A number of new serologic tests for typhoid fever havebeen introduced which detect antibodies (IgG or IgM) to various purifiedantigens of S. typhi

1- Widal test

Treatment

• Fluoroquinolones or third-generation cephalosporins

• Cholecystectomy may be necessary to abolish the chronic carrier state.

• Focal abscesses should be drained surgically when feasible

Paratyphoid fever

• It is similar in its symptoms to typhoid fever, but tendsto be milder, with a lower fatality rate.

• It is caused by S. paratyphi

• Rash may be more abundant

• May present as gastroenteritis specially in children

Reference

Dilshad Jaff. Brucellosis in Iraqi Kurdistan: An overview. Journal ofEntomology and Zoology Studies 2016; 4(4): 1113-1115.

• Warren E. Levinson, Peter Chin-Hong, Elizabeth Joyce, JesseNussbaum, Brian Schwart. 2018. Review of Medical Microbiology &Immunology, 15th edition. McGraw-Hill Education.

Mohammed I.S. Environmental, efface and filed study for sourceBrucella disease. International Journal of Advanced Research 2015;3( 7): 177-184.

M.J. Corbel. 2006. Brucellosis in humans and animals. Produced by the World Health Organization in collaboration with the Food and Agriculture Organization of the United Nations and World Organisation for Animal Health.

Thikra A. Mahmood, Salam J. Mohammed, Wisam S. Abbood(3), and others. Diagnostic and Epidemiologic Study of Human Brucellosis at Al-Najaf province. Kufa Journal for Nursing Sciences Vol. 6 No. 2 May through August 2016.

Yasmeen J. Al-Bayaa. Epidemiology of Human Brucellosis among Populations in Iraq's Provinces in 2015. JFac Med Baghdad 2017; Vol.59, No .2.

Khan KH. Recent trends in typhoid research—A Review. Int J Biosci. 2012; 2: 110-120