One way to diagnose "C. felis" is by taking blood and performing a peripheral blood smear to look for the erythrocytic piroplasms. The erythrocytic piroplasms are usually shaped like signet rings and are 1 to 1.5 µm. Not all cats that are infected will have the piroplasms on their blood smear, especially if they are early in disease course. Another method of diagnosing infection in sick cats is to take needle aspirates of affected organs and find the schizonts inside mononuclear cells in the tissues; examination of tissue is also useful for the diagnosis after cats have died. Blood samples can be sent away for polymerase chain reaction (PCR) testing to confirm infection. Other diseases that might resemble cytauxzoonosis should be ruled out. A major rule-out for "C. felis" is "Mycoplasma haemofelis" (formerly known as "Haemobartonella felis"); clinical signs can be similar to cytauxzoonosis and the organism may be confused on the peripheral smear. Because it causes similar signs in outdoor cats during the spring and summer, tularemia is another disease the veterinarian may want to rule out.

Other laboratory tests are often abnormal in sick cats. The CBC of an infected cat often shows a pancytopenia, or a decrease in red blood cells, white blood cells, and platelets; in some cases there is not a decrease in all three values. Clotting tests may be prolonged. Increased liver enzymes are common, and electrolyte disturbances, hyperglycemia, and acid-base disturbances can also be observed.

The following diagnostic methods are not routinely available to patients. Researchers have reported that they are more reliable at detecting infection, and in some cases can provide the physician with information to help determine whether "Blastocystis" infection is the cause of the patient's symptoms:

Serum antibody testing: A 1993 research study performed by the NIH with United States patients suggested that it was possible to distinguish symptomatic and asymptomatic infection with "Blastocystis" using serum antibody testing. The study used blood samples to measure the patient's immune reaction to chemicals present on the surface of the "Blastocystis" cell. It found that patients diagnosed with symptomatic "Blastocystis" infection exhibited a much higher immune response than controls who had "Blastocystis" infection but no symptoms. The study was repeated in 2003 at Ain Shams University in Egypt with Egyptian patients with equivalent results.

Fecal antibody testing: A 2003 study at Ain Shams University in Egypt indicated that patients symptomatically infected could be distinguished with a fecal antibody test. The study compared patients diagnosed with symptomatic "Blastocystis" infection to controls who had "Blastocystis" infection but no symptoms. In the group with symptoms, IgA antibodies to "Blastocystis" were detected in fecal specimens that were not present in the healthy control group.

Stool culture: Culturing has been shown to be a more reliable method of identifying infection. In 2006, researchers reported the ability to distinguish between disease causing and non-disease causing isolates of "Blastocystis" using stool culture. "Blastocystis" cultured from patients who were sick and diagnosed with "Blastocystis" infection produced large, highly adhesive amoeboid forms in culture. These cells were absent in "Blastocystis" cultures from healthy controls. Subsequent genetic analysis showed the "Blastocystis" from healthy controls was genetically distinct from that found in patients with symptoms. Protozoal culture is unavailable in most countries due to the cost and lack of trained staff able to perform protozoal culture.

Genetic analysis of isolates: Researchers have used techniques which allow the DNA of "Blastocystis" to be isolated from fecal specimens. This method has been reported to be more reliable at detecting "Blastocystis" in symptomatic patients than stool culture. This method also allows the species group of "Blastocystis" to be identified. Research is continuing into which species groups are associated with symptomatic (see Genetics and Symptoms) blastocystosis.

Immuno-fluorescence (IFA) stain: An IFA stain causes "Blastocystis" cells to glow when viewed under a microscope, making the diagnostic method more reliable. IFA stains are in use for Giardia and Cryptosporidium for both diagnostic purposes and water quality testing. A 1991 paper from the NIH described the laboratory development of one such stain. However, no company currently offers this stain commercially.

Neonatal sepsis of the newborn is an infection that has spread through the entire body. The inflammatory response to this systematic infection can be as serious as the infection itself. In infants that weigh under 1500 g, sepsis is the most common cause of death. Three to four percent of infants per 1000 births contract sepsis. The mortality rate from sepsis is near 25%. Infected sepsis in an infant can be identified by culturing the blood and spinal fluid and if suspected, intravenous antibiotics are usually started. Lumbar puncture is controversial because in some cases it has found not to be necessary while concurrently, without it estimates of missing up to one third of infants with meningitis is predicted.

The CDC states that PCR testing from a single blood draw is not sufficiently sensitive for "B." "henselae" testing, and can result in high false negative rates due to a small sample volume and levels below the limit of molecular detection.

"Bartonella" spp. are fastidious, slow-growing bacteria that are difficult to grow using traditional solid agar plate culture methods due to complex nutritional requirements and potentially a low number of circulating bacteria. This conventional method of culturing "Bartonella" spp. from blood inoculates plated directly onto solid agar plates requires an extended incubation period of 21 days due to the slow growth rate.

Diagnosis is usually performed by submitting multiple stool samples for examination by a parasitologist in a procedure known as an ova and parasite examination. About 30% of children with "D. fragilis" infection exhibit peripheral blood eosinophilia.

A minimum of three stool specimens having been immediately fixed in polyvinyl alcohol fixative, sodium acetate-acetic acid-formalin fixative, or Schaudinn's fixative should be submitted, as the protozoan does not remain morphologically identifiable for long. All specimens, regardless of consistency, are permanently stained prior to microscopic examination with an oil immersion lens. The disease may remain cryptic due to the lack of a cyst stage if these recommendations are not followed.

The trophozoite forms have been recovered from formed stool, thus the need to perform the ova and parasite examination on specimens other than liquid or soft stools. DNA fragment analysis provides excellent sensitivity and specificity when compared to microscopy for the detection of "D. fragilis" and both methods should be employed in laboratories with PCR capability. The most sensitive detection method is parasite culture, and the culture medium requires the addition of rice starch.

An indirect fluorescent antibody (IFA) for fixed stool specimens has been developed.

1. One researcher investigated the phenomenon of symptomatic relapse following treatment of infection with "D. fragilis" in association with its apparent disappearance from stool samples. The organism could still be detected in patients through colonoscopy or by examining stool samples taken in conjunction with a saline laxative.

2. A study found that trichrome staining, a traditional method for identification, had a sensitivity of 36% (9/25) when compared to stool culture.

3. An additional study found that the sensitivity of staining was 50% (2/4), and that the organism could be successfully cultured in stool specimens up to 12-hours old that were kept at room temperature.

"Bartonella" growth rates improve when cultured in an enrichment inoculation step in a liquid insect-based medium such as "Bartonella" α-Proteobacteria Growth Medium (BAPGM) or Schneider’s Drosophila-based insect powder medium. Several studies have optimized the growing conditions of "Bartonella" spp. cultures in these liquid media, with no change in bacterial protein expressions or host interactions "in vitro". Insect-based liquid media supports the growth and co-culturing of at least seven "Bartonella" species, reduces bacterial culturing time and facilitates PCR detection and isolation of "Bartonella" spp. from animal and patient samples. Research shows that DNA may be detected following direct extraction from blood samples and become negative following enrichment culture, thus PCR is recommended after direct sample extraction and also following incubation in enrichment culture. Several studies have successfully optimized sensitivity and specificity by using PCR amplification (pre-enrichment PCR) and enrichment culturing of blood draw samples, followed by PCR (post-enrichment PCR) and DNA sequence identification.

Opportunistic infections caused by Feline Leukemia Virus and Feline immunodeficiency virus retroviral infections can be treated with Lymphocyte T-Cell Immune Modulator.

Diagnosis is performed by determining if the infection is present, and then making a decision as to whether the infection is responsible for the symptoms. Diagnostic methods in clinical use have been reported to be of poor quality and more reliable methods have been reported in research papers.

For identification of infection, the only method clinically available in most areas is the "Ova and Parasite" (O&P) exam, which identifies the presence of the organism by microscopic examination of a chemically preserved stool specimen. This method is sometimes called "Direct Microscopy". In the United States, pathologists are required to report the presence of "Blastocystis" when found during an O&P exam, so a special test does not have to be ordered. Direct Microscopy is inexpensive, as the same test can identify a variety of gastrointestinal infections, such as "Giardia", "Entamoeba histolytica", "Cryptosporidium". However one laboratory director noted that pathologists using conventional microscopes failed to identify many "Blastocystis" infections, and indicated the necessity for special microscopic equipment for identification. The following table shows the sensitivity of Direct Microscopy in detecting "Blastocystis" when compared to stool culture, a more sensitive technique. Stool culture was considered by some researchers to be the most reliable technique, but a recent study found stool culture only detected 83% of individuals infected when compared to polymerase chain reaction (PCR) testing.

Reasons given for the failure of Direct Microscopy include: (1) Variable Shedding: The quantity of "Blastocystis" organisms varies substantially from day to day in infected humans and animals; (2) Appearance: Some forms of "Blastocystis" resemble fat cells or white blood cells, making it difficult to distinguish the organism from other cells in the stool sample; (3) Large number of morphological forms: "Blastocystis" cells can assume a variety of shapes, some have been described in detail only recently, so it is possible that additional forms exist but have not been identified.

Several methods have been cited in literature for determination of the significance of the finding of "Blastocystis":

1. Diagnosis only when large numbers of organism present: Some physicians consider "Blastocystis" infection to be a cause of illness only when large numbers are found in stool samples. Researchers have questioned this approach, noting that it is not used with any other protozoal infections, such as "Giardia" or "Entamoeba histolytica". Some researchers have reported no correlation between number of organisms present in stool samples and the level of symptoms. A study using polymerase chain reaction testing of stool samples suggested that symptomatic infection can exist even when sufficient quantities of the organism do not exist for identification through Direct Microscopy.

2. Diagnosis-by-exclusion: Some physicians diagnose "Blastocystis" infection by excluding all other causes, such as infection with other organisms, food intolerances, colon cancer, etc. This method can be time consuming and expensive, requiring many tests such as endoscopy and colonoscopy.

3. Disregarding "Blastocystis" : In the early to mid-1990s, some US physicians suggested all findings of "Blastocystis" are insignificant. No recent publications expressing this opinion could be found.

Diagnosis rests on the microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal fluid. Examination of many samples may be necessary, and not always sufficient, because direct stool examination is relatively insensitive, with a single sample only able to detect larvae in about 25% of cases. It can take 4 weeks from initial infection to the passage of larvae in the stool.

The stool can be examined in wet mounts:

- directly

- after concentration (formalin-ethyl acetate)

- after recovery of the larvae by the Baermann funnel technique

- after culture by the Harada-Mori filter paper technique

- after culture in agar plates

Culture techniques are the most sensitive, but are not routinely available in the West. In the UK, culture is available at either of the Schools of Tropical Medicine in Liverpool or London. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm eggs hatch on cooling and the larvae are very difficult to distinguish from Strongyloides.

Finding Strongyloides in the stool is negative in up to 70% of tests. It is important to undergo frequent stool sampling as well as duodenal biopsy if a bad infection is suspected. The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. Larvae may be detected in sputum from patients with disseminated strongyloidiasis.

Given the poor ability of stool examination to diagnose strongyloides, detecting antibodies by ELISA can be useful. Serology can cross-react with other parasites, remain positive for years after successful treatment or be falsely negative in immunocompromised patients. Infected patients will also often have an elevated eosinophil count, with an average of absolute eosinophil count of 1000 in one series. The combination of clinical suspicion, a positive antibody and a peripheral eosinophilia can be strongly suggestive of infection.

Recommendations for the diagnosis of congenital toxoplasmosis include: prenatal diagnosis based on testing of amniotic fluid and ultrasound examinations; neonatal diagnosis based on molecular testing of placenta and cord blood and comparative mother-child serologic tests and a clinical examination at birth; and early childhood diagnosis based on neurologic and ophthalmologic examinations and a serologic survey during the first year of life. During pregnancy, serological testing is recommended at three week intervals.

Even though diagnosis of toxoplasmosis heavily relies on serological detection of specific anti-"Toxoplasma" immunoglobulin, serological testing has limitations. For example, it may fail to detect the active phase of "T. gondii" infection because the specific anti-"Toxoplasma" IgG or IgM may not be produced until after several weeks of infection. As a result, a pregnant woman might test negative during the active phase of "T. gondii" infection leading to undetected and therefore untreated congenital toxoplasmosis. Also, the test may not detect "T. gondii" infections in immunocompromised patients because the titers of specific anti-"Toxoplasma" IgG or IgM may not rise in this type of patient.

Many PCR-based techniques have been developed to diagnose toxoplasmosis using clinical specimens that include amniotic fluid, blood, cerebrospinal fluid, and tissue biopsy. The most sensitive PCR-based technique is nested PCR, followed by hybridization of PCR products. The major downside to these techniques is that they are time consuming and do not provide quantitative data.

Real-time PCR is useful in pathogen detection, gene expression and regulation, and allelic discrimination. This PCR technique utilizes the 5' nuclease activity of "Taq" DNA polymerase to cleave a nonextendible, fluorescence-labeled hybridization probe during the extension phase of PCR. A second fluorescent dye, e.g., 6-carboxy-tetramethyl-rhodamine, quenches the fluorescence of the intact probe. The nuclease cleavage of the hybridization probe during the PCR releases the effect of quenching resulting in an increase of fluorescence proportional to the amount of PCR product, which can be monitored by a sequence detector.

Toxoplasmosis cannot be detected with immunostaining. Lymph nodes affected by "Toxoplasma" have characteristic changes, including poorly demarcated reactive germinal centers, clusters of monocytoid B cells, and scattered epithelioid histiocytes.

The classic triad of congenital toxoplasmosis includes: chorioretinitis, hydrocephalus, and intracranial artheriosclerosis.

Diagnosis of toxoplasmosis in humans is made by biological, serological, histological, or molecular methods, or by some combination of the above. Toxoplasmosis can be difficult to distinguish from primary central nervous system lymphoma. It mimics several other infectious diseases so clinical signs are non-specific and are not sufficiently characteristic for a definite diagnosis. As a result, the diagnosis is made by a trial of therapy (pyrimethamine, sulfadiazine, and folinic acid (USAN: leucovorin)), if the drugs produce no effect clinically and no improvement on repeat imaging.

"T. gondii" may also be detected in blood, amniotic fluid, or cerebrospinal fluid by using polymerase chain reaction. "T. gondii" may exist in a host as an inactive cyst that would likely evade detection.

Serological testing can detect "T. gondii" antibodies in blood serum, using methods including the Sabin–Feldman dye test (DT), the indirect hemagglutination assay, the indirect fluorescent antibody assay (IFA), the direct agglutination test, the latex agglutination test (LAT), the enzyme-linked immunosorbent assay (ELISA), and the immunosorbent agglutination assay test (IAAT).

The most commonly used tests to measure IgG antibody are the DT, the ELISA, the IFA, and the modified direct agglutination test. IgG antibodies usually appear within a week or two of infection, peak within one to two months, then decline at various rates. "Toxoplasma" IgG antibodies generally persist for life, and therefore may be present in the bloodstream as a result of either current or previous infection.

To some extent, acute toxoplasmosis infections can be differentiated from chronic infections using an IgG avidity test, which is a variation on the ELISA. In the first response to infection, toxoplasma-specific IgG has a low affinity for the toxoplasma antigen; in the following weeks and month, IgG affinity for the antigen increases. Based on the IgG avidity test, if the IgG in the infected individual has a high affinity, it means that the infection began three to five months before testing. This is particularly useful in congenital infection, where pregnancy status and gestational age at time of infection determines treatment.

In contrast to IgG, IgM antibodies can be used to detect acute infection, but generally not chronic infection. The IgM antibodies appear sooner after infection than the IgG antibodies and disappear faster than IgG antibodies after recovery. In most cases, "T. gondii"-specific IgM antibodies can first be detected approximately a week after acquiring primary infection, and decrease within one to six months; 25% of those infected are negative for "T. gondii"-specific IgM within seven months. However, IgM may be detectable months or years after infection, during the chronic phase, and false positives for acute infection are possible. The most commonly used tests for the measurement of IgM antibody are double-sandwich IgM-ELISA, the IFA test, and the immunosorbent agglutination assay (IgM-ISAGA). Commercial test kits often have low specificity, and the reported results are frequently misinterpreted.

Treatment depends on the type of opportunistic infection, but usually involves different antibiotics.

The preventative measure of keeping cats inside in areas with high infection rates can prevent infection. Approved tick treatments for cats can be used but have been shown not to fully prevent tick bites.

The most often used treatments for cytauxzoonosis are imidocarb dipropionate and a combination of atovaquone and azithromycin. Although imidocarb has been used for years, it is not particularly effective. In a large study, only 25% of cats treated with this drug and supportive care survived. 60% of sick cats treated with supportive care and the combination of the anti-malarial drug atovaquone and the antibiotic azithromycin survived infection.

Quick referral to a veterinarian equipped to treat the disease may be beneficial. All infected cats require supportive care, including careful fluids, nutritional support, treatment for complications, and often blood transfusion.

Cats that survive the infection should be kept indoors as they can be persistent carriers after surviving infection and might indirectly infect other cats after being themselves bitten by a vector tick.

Symptoms and the isolation of the virus pathogen the upper respiratory tract is diagnostic. Virus identification is specific immunologic methods and PCR. The presence of the virus can be rapidly confirmed by the detection of the virus antigen. The methods and materials used for identifying the RSV virus has a specificity and sensitivity approaching 85% to 95%. Not all studies confirm this sensitivity. Antigen detection has comparatively lower sensitivity rates that approach 65% to 75%.

Concomitant pinworm infection should also be excluded, although the association has not been proven. Successful treatment of the infection with iodoquinol, doxycycline, metronidazole, paromomycin, and secnidazole has been reported. Resistance requires the use of combination therapy to eradicate the organism. All persons living in the same residence should be screened for "D. fragilis", as asymptomatic carriers may provide a source of repeated infection. Paromomycin is an effective prophylactic for travellers who will encounter poor sanitation and unsafe drinking water.

Generally speaking, acanthocheilonemiasis does not show initial symptoms. However, if symptoms do arise, it is typically in individuals who are visiting highly infected areas rather than natives to those areas. A major common laboratory finding is an increase in specialized white blood cells, which is called eosinophilia.

Other symptoms include itchy skin, neurological symptoms, abdominal and chest pain, muscle pain, and swelling underneath the skin. If there are abnormally high levels of white blood cells, then a physical examination will most likely find an enlarged spleen or liver.

In certain scenarios, nematodes may physically lodge into the chest or abdomen, resulting in an inflammation. Diagnosis of this condition usually occurs via a blood smear examination under light microscopy.

Lumbar puncture should always be done is cases of suspected meningitis. In cases of eosiniphilc meningitis it will rarely produce worms even when they are present in the CSF, because they tend to cling to the end of nerves. Larvae are present in the CSF in only 1.9-10% of cases. However, as a case of eosiniphilic meningitis progresses, intracranial pressure and eosiniphil counts should rise. Increased levels of eosinophils in the CSF is a trademark of the eosiniphilic meningitis.

People infected with CMV develop antibodies to it, initially IgM later IgG indicating current infection and immunity respectively. If the virus is detected in the blood, saliva, urine or other body tissues, it means that the person has an active infection.

When infected with CMV, most women have no symptoms, but some may have symptoms resembling mononucleosis. Women who develop a mononucleosis-like illness during pregnancy should consult their medical provider.

The Centers for Disease Control and Prevention (CDC) does not recommend routine maternal screening for CMV infection during pregnancy because there is no test that can definitively rule out primary CMV infection during pregnancy. Women who are concerned about CMV infection during pregnancy should practice CMV prevention measures.Considering that the CMV virus is present in saliva, urine, tears, blood, mucus, and other bodily fluids, frequent hand washing with soap and water is important after contact with diapers or oral secretions, especially with a child who is in daycare or interacting with other young children on a regular basis.

A diagnosis of congenital CMV infection can be made if the virus is found in an infant's urine, saliva, blood, or other body tissues during the first week after birth. Antibody tests cannot be used to diagnose congenital CMV; a diagnosis can only be made if the virus is detected during the first week of life. Congenital CMV cannot be diagnosed if the infant is tested more than one week after birth.

Visually healthy infants are not routinely tested for CMV infection although only 10–20% will show signs of infection at birth though up to 80% may go onto show signs of prenatal infection in later life. If a pregnant woman finds out that she has become infected with CMV for the first time during her pregnancy, she should have her infant tested for CMV as soon as possible after birth.

Brain lesions, with invasion of both gray and white matter, can be seen on a CT or MRI. However MRI findings tend to be inconclusive, and usually include nonspecific lesions and ventricular enlargement. Sometimes a hemorrhage, probably produced by migrating worms, is present and of diagnostic value.

When physical examination of the newborn shows signs of a vertically transmitted infection, the examiner may test blood, urine, and spinal fluid for evidence of the infections listed above. Diagnosis can be confirmed by culture of one of the specific pathogens or by increased levels of IgM against the pathogen.

In a normal umbilical stump, you first see the umbilicus lose its characteristic bluish-white, moist appearance and become dry and black After several days to weeks, the stump should fall off and leave a pink fleshy wound which continues to heal as it becomes a normal umbilicus.

For an infected umbilical stump, diagnosis is usually made by the clinical appearance of the umbilical cord stump and the findings on history and physical examination. There may be some confusion, however, if a well-appearing neonate simply has some redness around the umbilical stump. In fact, a mild degree is common, as is some bleeding at the stump site with detachment of the umbilical cord. The picture may be clouded even further if caustic agents have been used to clean the stump or if silver nitrate has been used to cauterize granulomata of the umbilical stump.

During the 1950s there were outbreaks of omphalitis that then led to anti-bacterial treatment of the umbilical cord stump as the new standard of care. It was later determined that in developed countries keeping the cord dry is sufficient, (known as "dry cord care") as recommended by the American Academy of Pediatrics. The umbilical cord dries more quickly and separates more readily when exposed to air However, each hospital/birthing center has its own recommendations for care of the umbilical cord after delivery. Some recommend not using any medicinal washes on the cord. Other popular recommendations include triple dye, betadine, bacitracin, or silver sulfadiazine. With regards to the medicinal treatments, there is little data to support any one treatment (or lack thereof) over another. However one recent review of many studies supported the use of chlorhexidine treatment as a way to reduce risk of death by 23% and risk of omphalitis by anywhere between 27-56% in community settings in underdeveloped countries. This study also found that this treatment increased the time that it would take for the umbilical stump to separate or fall off by 1.7 days. Lastly this large review also supported the notion that in hospital settings no medicinal type of cord care treatment was better at reducing infections compared to dry cord care.

One strategy for the prevention of infection transmission between cats and people is to better educate people on the behaviour that puts them at risk for becoming infected.

Those at the highest risk of contracting a disease from a cat are those with behaviors that include: being licked, sharing food, sharing kithchen utensils, kissing, and sleeping with a cat. The very young, the elderly and those who are immunocompromised increase their risk of becoming infected when sleeping with their cats (and dogs). The CDC recommends that cat owners not allow a cat to lick your face because it can result in disease transmission. If someone is licked on their face, mucous membranes or an open wound, the risk for infection is reduced if the area is immediately washed with soap and water. Maintaining the health of the animal by regular inspection for fleas and ticks, scheduling deworming medications along with veterinary exams will also reduce the risk of acquiring a feline zoonosis.

Recommendations for the prevention of ringworm transmission to people include:

- regularly vacuuming areas of the home that pets commonly visit helps to remove fur or flakes of skin

- washing the hands with soap and running water after playing with or petting your pet.

- wearing gloves and long sleeves when handling cats infected with.

- disinfect areas the pet has spent time in, including surfaces and bedding.

- the spores of this fungus can be killed with common disinfectants like chlorine bleach diluted 1:10 (1/4 cup in 1 gallon of water), benzalkonium chloride, or strong detergents.

- not handling cats with ringworm by those whose immune system is weak in any way (if you have HIV/AIDS, are undergoing cancer treatment, or are taking medications that suppress the immune system, for example).

- taking the cat to the veterinarian if ringworm infection is suspected.

A study conducted on 452 patients revealed that the genotype responsible for higher IL-10 expression makes HIV infected people more susceptible to tuberculosis infection. Another study on HIV-TB co-infected patients also concluded that higher level of IL-10 and IL-22 makes TB patient more susceptible to Immune reconstitution inflammatory syndrome (IRIS). It is also seen that HIV co-infection with tuberculosis also reduces concentration of immunopathogenic matrix metalloproteinase (MMPs) leading to reduced inflammatory immunopathology.

The abscesses within the muscle must be drained surgically (not all patient require surgery if there is no abscess). Antibiotics are given for a minimum of three weeks to clear the infection.