Case Investigation and Patient Interview

Reporting

There are multiple ways to submit malaria case investigation reports to CDC. However, the preference is to submit them using the CDC malaria electronic case report form (eCRF) or via HL7 using the malaria message mapping guide (MMG) standards.

• CDC supports HL7 reporting for malaria via two MMGs: GenV2 and the malaria specific MMG. Reach out to the CDC malaria surveillance epidemiologist to discuss onboarding for the malaria MMG. Reporting via GenV2 alone does not cover all aspects of the case investigation and therefore full case reports should still be sent to CDC in another format.

• To complete a malaria electronic case report form (eCRF), follow the instructions provided on pages 4-5 of the CDC eCRF. If the CDC eCRF is not used then follow jurisdiction-specific recommendations to complete the investigation using a customized investigation form and online reporting system.

• Instructions specific to the CDC malaria eCRF:
  • Page 3 of the eCRF form collects additional data for multiple hospitalizations, lab tests, travel histories, and other data.
  • Note that Chemoprophylaxis (section 5 a – c of the malaria case report form) refers to medication taken before, during, and after travel to prevent malaria illness. Treatments given to cure the acute illness should be documented in section 5 h of the malaria case report form.
  • Submit individual eCRFs (or .csv reports derived from the pdf files) to the CDC domestic malaria surveillance epidemiologist or to the mailbox malariasurveillance@cdc.gov via secure email. Note that some secure email systems require individual credentials, which aren’t accessible from the group inbox. Do not include personally identifiable information (PII) in the body or subject of the email.

Relapse

• A relapse (only in P. vivax or P. ovale species) or a subsequent episode of malaria in a person who previously had malaria should be counted as an additional case (requiring a separate case report form) unless the case is indicated as a treatment failure within 4 weeks of initial presentation (recrudescence of original infection).
  • The infecting species should be determined, and potentially relapsing cases should be carefully investigated to assess if the person had traveled since their previous illness.
  • CDC classifies cases according to where the person acquired the infection. If the initial infection was acquired internationally, then the relapse case is classified as imported. If the initial infection was acquired through a local exposure, for example by locally acquired mosquito transmission, then those relapse cases will also be classified as introduced.
  • There are rare case reports for persons who have a late recrudescence, occurring many months or years after an earlier illness. A late recrudescence is difficult to prove. These rare cases must be thoroughly investigated to rule out other exposures and are often classified as cryptic.

Case investigation

Provide as much information as possible for the case investigation. CDC uses data to classify risk groups, describe disease severity, and determine if treatment follows CDC’s guidelines.

• Antimalarial treatment: Note that some antimalarials may not be immediately initiated, so the information available immediately upon diagnosis may not be complete. For example, follow-on treatment for patients with severe malaria is recommended to start subsequent to the intravenous artesunate medication. And primaquine or tafenoquine to prevent P. vivax or P. ovale relapses are recommended to start after G6PD testing is completed and results received (typically 1 to 2 weeks after diagnosis).
  • More information on malaria diagnosis and treatment can be found in the Malaria Clinical Guidelines Quick Reference (Appendix C).

• Travel history: If a person traveled to more than one endemic country, then use the repeating block sections of the eCRF to include all countries traveled in and their dates, if available. If it is not possible to determine the exact country of disease exposure, then indicate the region. For example, if a person traveled for two weeks in Nigeria and two weeks in Benin then indicate the date of departure for each country and the duration they were there. If using a jurisdiction-specific reporting system that does not allow for multiple countries to be reported, then indicate the region. For the above example, indicate West Africa and the total duration there (4 weeks) and the date of departure from the location.
  • If country-specific travel details are missing, then indicate the Region traveled. Partial dates (year and month, or year alone) can be provided. Because travel information is used to classify case acquisition, it is not recommended to indicate ‘unknown’ for a person who traveled in multiple countries.

• Please follow the CSTE guidelines for completing the “Country of Usual Residence” data element. If the person is establishing residence in the U.S., then “Country of Usual Residence” should be “United States.” However, if the malaria exposure occurred when they were previously residents of another country then the “Subject’s country of residence prior to most recent travel” should be their former country of residence.

During the patient interview, counsel all patients diagnosed with malaria to avoid mosquito bites during their convalescence.

CDC provides malaria consultations to clinical providers through the CDC Malaria Hotline. If we receive an inquiry from the Malaria Hotline regarding a patient who has delayed parasite clearance or who has recurrent parasitemia within 4 weeks of initial treatment, then we usually request whole blood specimens (pre and/or post-treatment) be sent to CDC for molecular surveillance. In that situation CDC will reach out to the state health department epidemiologists to coordinate specimen shipping from the hospital to the PHL and then to CDC.

For patients who are lost to follow-up, rely on medical records or healthcare provider information to complete the malaria case report. The most important task is to try to determine how malaria was acquired. If it is known that the patient traveled internationally but if all details are not known, then indicate “Yes, traveled outside the U.S.”, and leave the specific country and travel dates blank. This will result in classifying the case as “Imported” with travel details “Unknown.” If no information is available, then indicate that the case importation status is “Unknown.”

If you have any questions or concerns about a case, including the timing of travel and illness onset, reach out to the CDC malaria surveillance epidemiologist or the CDC Malaria Hotline (after hours).

If the initial case investigation does not yield a recent travel history (in the past two years) or prior malaria illness (within 2 – 3 years), then an enhanced investigation is warranted to assess their classification as possibly cryptic or locally acquired. If you think an enhanced investigation is necessary, please reach out to your state health department (if applicable) and the CDC Malaria Branch immediately (malaria@cdc.gov or 770-488-7788).

Enhanced investigation

For cases under enhanced investigation, a more detailed patient interview should review the risk factors for acquiring malaria, including detailed travel history, sick contacts (e.g., household members), occupation, outdoor activities:

• Ask about lifetime and recent travel to a malaria-endemic country:
  • Identify specific dates the patient was in a malaria-endemic country and the areas visited.
  • If the person previously lived in a malaria-endemic country, when did they immigrate to the U.S. or to another non-endemic country?
• Ask about prior diagnoses of malaria (in lifetime), or previous unexplained febrile illness after international travel:
  • If yes, specific dates and if (and what) treatment received?
  • If diagnosed with a relapsing species (P. vivax or P. ovale), did they receive antirelapse therapy (primaquine for 14 days, or a single dose of tafenoquine)?
• Ask about blood exposures such as blood transfusions, organ transplants, needlestick injuries, unsafe needle sharing, or home tattoos.
• Prior to illness, were there any visitors, household members, co-workers who were sick with malaria or another febrile illness?
• Has the patient been in an area where Babesia parasites are transmitted? Has the patient had a recent tick bite?
• Has the patient recently slept outdoors? Are they currently or have they recently experienced unstable housing or homelessness?

Obtain additional details from the medical record including past medical history (especially immunocompromising conditions, asplenia, and pregnancy status), recent hospitalizations and medical procedures.

Please contact CDC (CDC malaria surveillance epidemiologist or the CDC Hotline malaria@cdc.gov) for malaria diagnosed in a newborn without travel (congenital malaria). Congenital cases occurring in non-endemic settings have been reported weeks or up to two months after birth.

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¹Jurisdiction-specific recommendations should be followed. Typically, the malaria case investigations are initiated between 24 hours and one week from the notification. If there is concern that the case may be locally acquired or doesn't have a travel history to a country with ongoing malaria transmission in approximately the previous two years, or if the patient is severely ill, then urgency is recommended to ensure timely public health responses and appropriate treatment.